[PATCH 00/12] Add spi-hid transport driver

[PATCH 00/12] Add spi-hid transport driver

[Jingyuan Liang]

This series picks up the spi-hid driver work originally started by
Microsoft. The patch breakdown has been modified and the implementation has
been refactored to address upstream feedback and testing issues. We are
submitting this as a new series while keeping the original sign-off
chain to reflect the history.

Same as the original series, there is a change to HID documentation, some
HID core changes to support a SPI device, the SPI HID transport driver,
and HID over SPI Device Tree binding. We have added the HID over SPI ACPI
support, power management, panel follower, and quirks for Ilitek touch
controllers.

Original authors: Jarrett Schultz <jaschultz@microsoft.com>,
		  Dmitry Antipov <dmanti@microsoft.com>
Link: https://lore.kernel.org/r/86b63b7b-afda-d7f4-7bfa-175085d5a8ef@gmail.com

Signed-off-by: Jingyuan Liang <jingyliang@chromium.org>
---
Angela Czubak (2):
      HID: spi-hid: add transport driver skeleton for HID over SPI bus
      HID: spi_hid: add ACPI support for SPI over HID

Jarrett Schultz (3):
      Documentation: Correction in HID output_report callback description.
      HID: Add BUS_SPI support and define HID_SPI_DEVICE macro
      HID: spi_hid: add device tree support for SPI over HID

Jingyuan Liang (7):
      HID: spi-hid: add spi-hid driver HID layer
      HID: spi-hid: add HID SPI protocol implementation
      HID: spi_hid: add spi_hid traces
      dt-bindings: input: Document hid-over-spi DT schema
      HID: spi-hid: add power management implementation
      HID: spi-hid: add panel follower support
      HID: spi-hid: add quirkis to support mode switch for Ilitek touch

 .../devicetree/bindings/input/hid-over-spi.yaml    |  153 ++
 Documentation/hid/hid-transport.rst                |    4 +-
 drivers/hid/Kconfig                                |    2 +
 drivers/hid/Makefile                               |    2 +
 drivers/hid/hid-core.c                             |    3 +
 drivers/hid/spi-hid/Kconfig                        |   45 +
 drivers/hid/spi-hid/Makefile                       |   11 +
 drivers/hid/spi-hid/spi-hid-acpi.c                 |  254 ++++
 drivers/hid/spi-hid/spi-hid-core.c                 | 1493 ++++++++++++++++++++
 drivers/hid/spi-hid/spi-hid-core.h                 |   94 ++
 drivers/hid/spi-hid/spi-hid-of.c                   |  244 ++++
 drivers/hid/spi-hid/spi-hid.h                      |   51 +
 include/linux/hid.h                                |    2 +
 include/trace/events/spi_hid.h                     |  156 ++
 14 files changed, 2512 insertions(+), 2 deletions(-)
---
base-commit: 05f7e89ab9731565d8a62e3b5d1ec206485eeb0b
change-id: 20260212-send-upstream-75f6fd9ed92e

Best regards,
-- 
Jingyuan Liang <jingyliang@chromium.org>

[PATCH 01/12] Documentation: Correction in HID output_report callback description.

[Jingyuan Liang]

From: Jarrett Schultz <jaschultz@microsoft.com>

Originally output_report callback was described as must-be asynchronous,
but that is not the case in some implementations, namely i2c-hid.
Correct the documentation to say that it may be asynchronous.

Signed-off-by: Dmitry Antipov <dmanti@microsoft.com>
Signed-off-by: Jingyuan Liang <jingyliang@chromium.org>
---
 Documentation/hid/hid-transport.rst | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/Documentation/hid/hid-transport.rst b/Documentation/hid/hid-transport.rst
index 6f1692da296c..2008cf432af1 100644
--- a/Documentation/hid/hid-transport.rst
+++ b/Documentation/hid/hid-transport.rst
@@ -327,8 +327,8 @@ The available HID callbacks are:
 
    Send raw output report via intr channel. Used by some HID device drivers
    which require high throughput for outgoing requests on the intr channel. This
-   must not cause SET_REPORT calls! This must be implemented as asynchronous
-   output report on the intr channel!
+   must not cause SET_REPORT calls! This call might be asynchronous, so the
+   caller should not expect an immediate response!
 
    ::
 

-- 
2.53.0.473.g4a7958ca14-goog

[PATCH 02/12] HID: Add BUS_SPI support and define HID_SPI_DEVICE macro

[Jingyuan Liang]

From: Jarrett Schultz <jaschultz@microsoft.com>

If connecting a hid_device with bus field indicating BUS_SPI print out
"SPI" in the debug print.

Macro sets the bus field to BUS_SPI and uses arguments to set vendor
product fields.

Signed-off-by: Dmitry Antipov <dmanti@microsoft.com>
Signed-off-by: Jingyuan Liang <jingyliang@chromium.org>
---
 drivers/hid/hid-core.c | 3 +++
 include/linux/hid.h    | 2 ++
 2 files changed, 5 insertions(+)

diff --git a/drivers/hid/hid-core.c b/drivers/hid/hid-core.c
index a5b3a8ca2fcb..813c9c743ccd 100644
--- a/drivers/hid/hid-core.c
+++ b/drivers/hid/hid-core.c
@@ -2316,6 +2316,9 @@ int hid_connect(struct hid_device *hdev, unsigned int connect_mask)
 	case BUS_I2C:
 		bus = "I2C";
 		break;
+	case BUS_SPI:
+		bus = "SPI";
+		break;
 	case BUS_SDW:
 		bus = "SOUNDWIRE";
 		break;
diff --git a/include/linux/hid.h b/include/linux/hid.h
index dce862cafbbd..957f322a0ebd 100644
--- a/include/linux/hid.h
+++ b/include/linux/hid.h
@@ -786,6 +786,8 @@ struct hid_descriptor {
 	.bus = BUS_BLUETOOTH, .vendor = (ven), .product = (prod)
 #define HID_I2C_DEVICE(ven, prod)				\
 	.bus = BUS_I2C, .vendor = (ven), .product = (prod)
+#define HID_SPI_DEVICE(ven, prod)				\
+	.bus = BUS_SPI, .vendor = (ven), .product = (prod)
 
 #define HID_REPORT_ID(rep) \
 	.report_type = (rep)

-- 
2.53.0.473.g4a7958ca14-goog

[PATCH 03/12] HID: spi-hid: add transport driver skeleton for HID over SPI bus

[Jingyuan Liang]

From: Angela Czubak <acz@semihalf.com>

Create spi-hid folder and add Kconfig and Makefile for spi-hid driver.
Add basic device structure, definitions, and probe/remove functions.

Signed-off-by: Dmitry Antipov <dmanti@microsoft.com>
Signed-off-by: Angela Czubak <acz@semihalf.com>
Signed-off-by: Jingyuan Liang <jingyliang@chromium.org>
---
 drivers/hid/Kconfig                |   2 +
 drivers/hid/Makefile               |   2 +
 drivers/hid/spi-hid/Kconfig        |  15 +++
 drivers/hid/spi-hid/Makefile       |   9 ++
 drivers/hid/spi-hid/spi-hid-core.c | 212 +++++++++++++++++++++++++++++++++++++
 5 files changed, 240 insertions(+)

diff --git a/drivers/hid/Kconfig b/drivers/hid/Kconfig
index 920a64b66b25..c6ae23bfb75d 100644
--- a/drivers/hid/Kconfig
+++ b/drivers/hid/Kconfig
@@ -1434,6 +1434,8 @@ source "drivers/hid/bpf/Kconfig"
 
 source "drivers/hid/i2c-hid/Kconfig"
 
+source "drivers/hid/spi-hid/Kconfig"
+
 source "drivers/hid/intel-ish-hid/Kconfig"
 
 source "drivers/hid/amd-sfh-hid/Kconfig"
diff --git a/drivers/hid/Makefile b/drivers/hid/Makefile
index 361a7daedeb8..6b43e789b39a 100644
--- a/drivers/hid/Makefile
+++ b/drivers/hid/Makefile
@@ -169,6 +169,8 @@ obj-$(CONFIG_USB_KBD)		+= usbhid/
 
 obj-$(CONFIG_I2C_HID_CORE)	+= i2c-hid/
 
+obj-$(CONFIG_SPI_HID_CORE)	+= spi-hid/
+
 obj-$(CONFIG_INTEL_ISH_HID)	+= intel-ish-hid/
 
 obj-$(CONFIG_AMD_SFH_HID)       += amd-sfh-hid/
diff --git a/drivers/hid/spi-hid/Kconfig b/drivers/hid/spi-hid/Kconfig
new file mode 100644
index 000000000000..836fdefe8345
--- /dev/null
+++ b/drivers/hid/spi-hid/Kconfig
@@ -0,0 +1,15 @@
+# SPDX-License-Identifier: GPL-2.0-only
+#
+# Copyright (c) 2021 Microsoft Corporation
+#
+
+menuconfig SPI_HID
+	tristate "SPI HID support"
+	default y
+	depends on SPI
+
+if SPI_HID
+
+config SPI_HID_CORE
+	tristate
+endif
diff --git a/drivers/hid/spi-hid/Makefile b/drivers/hid/spi-hid/Makefile
new file mode 100644
index 000000000000..92e24cddbfc2
--- /dev/null
+++ b/drivers/hid/spi-hid/Makefile
@@ -0,0 +1,9 @@
+# SPDX-License-Identifier: GPL-2.0-only
+#
+# Makefile for the SPI HID input drivers
+#
+# Copyright (c) 2021 Microsoft Corporation
+#
+
+obj-$(CONFIG_SPI_HID_CORE)	+= spi-hid.o
+spi-hid-objs 			= spi-hid-core.o
diff --git a/drivers/hid/spi-hid/spi-hid-core.c b/drivers/hid/spi-hid/spi-hid-core.c
new file mode 100644
index 000000000000..5431c60efd50
--- /dev/null
+++ b/drivers/hid/spi-hid/spi-hid-core.c
@@ -0,0 +1,212 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * HID over SPI protocol implementation
+ *
+ * Copyright (c) 2021 Microsoft Corporation
+ * Copyright (c) 2026 Google LLC
+ *
+ * This code is partly based on "HID over I2C protocol implementation:
+ *
+ *  Copyright (c) 2012 Benjamin Tissoires <benjamin.tissoires@gmail.com>
+ *  Copyright (c) 2012 Ecole Nationale de l'Aviation Civile, France
+ *  Copyright (c) 2012 Red Hat, Inc
+ *
+ *  which in turn is partly based on "USB HID support for Linux":
+ *
+ *  Copyright (c) 1999 Andreas Gal
+ *  Copyright (c) 2000-2005 Vojtech Pavlik <vojtech@suse.cz>
+ *  Copyright (c) 2005 Michael Haboustak <mike-@cinci.rr.com> for Concept2, Inc
+ *  Copyright (c) 2007-2008 Oliver Neukum
+ *  Copyright (c) 2006-2010 Jiri Kosina
+ */
+
+#include <linux/device.h>
+#include <linux/hid.h>
+#include <linux/hid-over-spi.h>
+#include <linux/interrupt.h>
+#include <linux/module.h>
+#include <linux/slab.h>
+#include <linux/spi/spi.h>
+
+/* struct spi_hid_conf - Conf provided to the core */
+struct spi_hid_conf {
+	u32 input_report_header_address;
+	u32 input_report_body_address;
+	u32 output_report_address;
+	u8 read_opcode;
+	u8 write_opcode;
+};
+
+/**
+ * struct spihid_ops - Ops provided to the core
+ * @power_up: do sequencing to power up the device
+ * @power_down: do sequencing to power down the device
+ * @assert_reset: do sequencing to assert the reset line
+ * @deassert_reset: do sequencing to deassert the reset line
+ */
+struct spihid_ops {
+	int (*power_up)(struct spihid_ops *ops);
+	int (*power_down)(struct spihid_ops *ops);
+	int (*assert_reset)(struct spihid_ops *ops);
+	int (*deassert_reset)(struct spihid_ops *ops);
+	void (*sleep_minimal_reset_delay)(struct spihid_ops *ops);
+};
+
+/* Driver context */
+struct spi_hid {
+	struct spi_device	*spi;	/* spi device. */
+	struct hid_device	*hid;	/* pointer to corresponding HID dev. */
+
+	struct spihid_ops	*ops;
+	struct spi_hid_conf	*conf;
+
+	enum hidspi_power_state power_state;
+
+	u32 regulator_error_count;
+	int regulator_last_error;
+	u32 bus_error_count;
+	int bus_last_error;
+	u32 dir_count;	/* device initiated reset count. */
+};
+
+static const char *spi_hid_power_mode_string(enum hidspi_power_state power_state)
+{
+	switch (power_state) {
+	case HIDSPI_ON:
+		return "d0";
+	case HIDSPI_SLEEP:
+		return "d2";
+	case HIDSPI_OFF:
+		return "d3";
+	default:
+		return "unknown";
+	}
+}
+
+static irqreturn_t spi_hid_dev_irq(int irq, void *_shid)
+{
+	return IRQ_HANDLED;
+}
+
+static ssize_t bus_error_count_show(struct device *dev,
+				    struct device_attribute *attr, char *buf)
+{
+	struct spi_hid *shid = dev_get_drvdata(dev);
+
+	return sysfs_emit(buf, "%d (%d)\n",
+			  shid->bus_error_count, shid->bus_last_error);
+}
+static DEVICE_ATTR_RO(bus_error_count);
+
+static ssize_t regulator_error_count_show(struct device *dev,
+					  struct device_attribute *attr,
+					  char *buf)
+{
+	struct spi_hid *shid = dev_get_drvdata(dev);
+
+	return sysfs_emit(buf, "%d (%d)\n",
+			  shid->regulator_error_count,
+			  shid->regulator_last_error);
+}
+static DEVICE_ATTR_RO(regulator_error_count);
+
+static ssize_t device_initiated_reset_count_show(struct device *dev,
+						 struct device_attribute *attr,
+						 char *buf)
+{
+	struct spi_hid *shid = dev_get_drvdata(dev);
+
+	return sysfs_emit(buf, "%d\n", shid->dir_count);
+}
+static DEVICE_ATTR_RO(device_initiated_reset_count);
+
+static struct attribute *spi_hid_attrs[] = {
+	&dev_attr_bus_error_count.attr,
+	&dev_attr_regulator_error_count.attr,
+	&dev_attr_device_initiated_reset_count.attr,
+	NULL	/* Terminator */
+};
+
+static const struct attribute_group spi_hid_group = {
+	.attrs = spi_hid_attrs,
+};
+
+const struct attribute_group *spi_hid_groups[] = {
+	&spi_hid_group,
+	NULL
+};
+EXPORT_SYMBOL_GPL(spi_hid_groups);
+
+int spi_hid_core_probe(struct spi_device *spi, struct spihid_ops *ops,
+		       struct spi_hid_conf *conf)
+{
+	struct device *dev = &spi->dev;
+	struct spi_hid *shid;
+	int error;
+
+	if (spi->irq <= 0)
+		return dev_err_probe(dev, spi->irq ?: -EINVAL, "Missing IRQ\n");
+
+	shid = devm_kzalloc(dev, sizeof(*shid), GFP_KERNEL);
+	if (!shid)
+		return -ENOMEM;
+
+	shid->spi = spi;
+	shid->power_state = HIDSPI_ON;
+	shid->ops = ops;
+	shid->conf = conf;
+
+	spi_set_drvdata(spi, shid);
+
+	/*
+	 * At the end of probe we initialize the device:
+	 *   0) assert reset, bias the interrupt line
+	 *   1) sleep minimal reset delay
+	 *   2) request IRQ
+	 *   3) power up the device
+	 *   4) deassert reset (high)
+	 * After this we expect an IRQ with a reset response.
+	 */
+
+	shid->ops->assert_reset(shid->ops);
+
+	shid->ops->sleep_minimal_reset_delay(shid->ops);
+
+	error = devm_request_threaded_irq(dev, spi->irq, NULL, spi_hid_dev_irq,
+					  IRQF_ONESHOT, dev_name(&spi->dev), shid);
+	if (error) {
+		dev_err(dev, "%s: unable to request threaded IRQ.", __func__);
+		return error;
+	}
+
+	error = shid->ops->power_up(shid->ops);
+	if (error) {
+		dev_err(dev, "%s: could not power up.", __func__);
+		return error;
+	}
+
+	shid->ops->deassert_reset(shid->ops);
+
+	dev_dbg(dev, "%s: d3 -> %s.", __func__,
+		spi_hid_power_mode_string(shid->power_state));
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(spi_hid_core_probe);
+
+void spi_hid_core_remove(struct spi_device *spi)
+{
+	struct spi_hid *shid = spi_get_drvdata(spi);
+	struct device *dev = &spi->dev;
+	int error;
+
+	shid->ops->assert_reset(shid->ops);
+	error = shid->ops->power_down(shid->ops);
+	if (error)
+		dev_err(dev, "failed to disable regulator.");
+}
+EXPORT_SYMBOL_GPL(spi_hid_core_remove);
+
+MODULE_DESCRIPTION("HID over SPI transport driver");
+MODULE_AUTHOR("Dmitry Antipov <dmanti@microsoft.com>");
+MODULE_LICENSE("GPL");

-- 
2.53.0.473.g4a7958ca14-goog

[PATCH 04/12] HID: spi-hid: add spi-hid driver HID layer

[Jingyuan Liang]

Add HID low level driver callbacks to register SPI as a HID driver, and
an external touch device as a HID device.

Signed-off-by: Dmitry Antipov <dmanti@microsoft.com>
Signed-off-by: Angela Czubak <acz@semihalf.com>
Signed-off-by: Jingyuan Liang <jingyliang@chromium.org>
---
 drivers/hid/spi-hid/spi-hid-core.c | 519 +++++++++++++++++++++++++++++++++++++
 1 file changed, 519 insertions(+)

diff --git a/drivers/hid/spi-hid/spi-hid-core.c b/drivers/hid/spi-hid/spi-hid-core.c
index 5431c60efd50..18b035324f06 100644
--- a/drivers/hid/spi-hid/spi-hid-core.c
+++ b/drivers/hid/spi-hid/spi-hid-core.c
@@ -20,13 +20,69 @@
  *  Copyright (c) 2006-2010 Jiri Kosina
  */
 
+#include <linux/completion.h>
+#include <linux/crc32.h>
 #include <linux/device.h>
+#include <linux/err.h>
 #include <linux/hid.h>
 #include <linux/hid-over-spi.h>
 #include <linux/interrupt.h>
+#include <linux/jiffies.h>
 #include <linux/module.h>
+#include <linux/mutex.h>
 #include <linux/slab.h>
 #include <linux/spi/spi.h>
+#include <linux/string.h>
+#include <linux/sysfs.h>
+#include <linux/unaligned.h>
+
+#define SPI_HID_OUTPUT_REPORT_CONTENT_ID_DESC_REQUEST	0x00
+
+#define SPI_HID_RESP_TIMEOUT	1000
+
+/* Protocol message size constants */
+#define SPI_HID_OUTPUT_HEADER_LEN		8
+
+/* flags */
+/*
+ * ready flag indicates that the FW is ready to accept commands and
+ * requests. The FW becomes ready after sending the report descriptor.
+ */
+#define SPI_HID_READY	0
+
+/* Raw input buffer with data from the bus */
+struct spi_hid_input_buf {
+	u8 header[HIDSPI_INPUT_HEADER_SIZE];
+	u8 body[HIDSPI_INPUT_BODY_HEADER_SIZE];
+	u8 content[];
+};
+
+/* Raw output report buffer to be put on the bus */
+struct spi_hid_output_buf {
+	u8 header[SPI_HID_OUTPUT_HEADER_LEN];
+	u8 content[];
+};
+
+/* Data necessary to send an output report */
+struct spi_hid_output_report {
+	u8 report_type;
+	u16 content_length;
+	u8 content_id;
+	u8 *content;
+};
+
+/* Processed data from a device descriptor */
+struct spi_hid_device_descriptor {
+	u16 hid_version;
+	u16 report_descriptor_length;
+	u16 max_input_length;
+	u16 max_output_length;
+	u16 max_fragment_length;
+	u16 vendor_id;
+	u16 product_id;
+	u16 version_id;
+	u8 no_output_report_ack;
+};
 
 /* struct spi_hid_conf - Conf provided to the core */
 struct spi_hid_conf {
@@ -60,8 +116,26 @@ struct spi_hid {
 	struct spihid_ops	*ops;
 	struct spi_hid_conf	*conf;
 
+	struct spi_hid_device_descriptor desc;	/* HID device descriptor. */
+	struct spi_hid_output_buf *output;	/* Output buffer. */
+	struct spi_hid_input_buf *input;	/* Input buffer. */
+	struct spi_hid_input_buf *response;	/* Response buffer. */
+
+	u16 response_length;
+	u16 bufsize;
+
 	enum hidspi_power_state power_state;
 
+	u8 reset_attempts;	/* The number of reset attempts. */
+
+	unsigned long flags;	/* device flags. */
+
+	/* Control lock to make sure one output transaction at a time. */
+	struct mutex output_lock;
+	struct completion output_done;
+
+	u32 report_descriptor_crc32;	/* HID report descriptor crc32 checksum. */
+
 	u32 regulator_error_count;
 	int regulator_last_error;
 	u32 bus_error_count;
@@ -69,6 +143,33 @@ struct spi_hid {
 	u32 dir_count;	/* device initiated reset count. */
 };
 
+static struct hid_ll_driver spi_hid_ll_driver;
+
+static void spi_hid_populate_output_header(u8 *buf,
+					   const struct spi_hid_conf *conf,
+					   const struct spi_hid_output_report *report)
+{
+	buf[0] = conf->write_opcode;
+	put_unaligned_be24(conf->output_report_address, &buf[1]);
+	buf[4] = report->report_type;
+	put_unaligned_le16(report->content_length, &buf[5]);
+	buf[7] = report->content_id;
+}
+
+static int spi_hid_output(struct spi_hid *shid, const void *buf, u16 length)
+{
+	int error;
+
+	error = spi_write(shid->spi, buf, length);
+
+	if (error) {
+		shid->bus_error_count++;
+		shid->bus_last_error = error;
+	}
+
+	return error;
+}
+
 static const char *spi_hid_power_mode_string(enum hidspi_power_state power_state)
 {
 	switch (power_state) {
@@ -83,11 +184,416 @@ static const char *spi_hid_power_mode_string(enum hidspi_power_state power_state
 	}
 }
 
+static void spi_hid_stop_hid(struct spi_hid *shid)
+{
+	struct hid_device *hid = shid->hid;
+
+	shid->hid = NULL;
+	clear_bit(SPI_HID_READY, &shid->flags);
+
+	if (hid)
+		hid_destroy_device(hid);
+}
+
+static int spi_hid_send_output_report(struct spi_hid *shid,
+				      struct spi_hid_output_report *report)
+{
+	struct spi_hid_output_buf *buf = shid->output;
+	struct device *dev = &shid->spi->dev;
+	u16 report_length;
+	u16 padded_length;
+	u8 padding;
+	int error;
+
+	guard(mutex)(&shid->output_lock);
+	if (report->content_length > shid->desc.max_output_length) {
+		dev_err(dev, "Output report too big, content_length 0x%x.",
+			report->content_length);
+		return -E2BIG;
+	}
+
+	spi_hid_populate_output_header(buf->header, shid->conf, report);
+
+	if (report->content_length)
+		memcpy(&buf->content, report->content, report->content_length);
+
+	report_length = sizeof(buf->header) + report->content_length;
+	padded_length = round_up(report_length,	4);
+	padding = padded_length - report_length;
+	memset(&buf->content[report->content_length], 0, padding);
+
+	error = spi_hid_output(shid, buf, padded_length);
+	if (error)
+		dev_err(dev, "Failed output transfer: %d.", error);
+
+	return error;
+}
+
+static int spi_hid_sync_request(struct spi_hid *shid,
+				struct spi_hid_output_report *report)
+{
+	struct device *dev = &shid->spi->dev;
+	int error;
+
+	error = spi_hid_send_output_report(shid, report);
+	if (error)
+		return error;
+
+	error = wait_for_completion_interruptible_timeout(&shid->output_done,
+							  msecs_to_jiffies(SPI_HID_RESP_TIMEOUT));
+	if (error == 0) {
+		dev_err(dev, "Response timed out.");
+		return -ETIMEDOUT;
+	}
+
+	return 0;
+}
+
+/*
+ * This function returns the length of the report descriptor, or a negative
+ * error code if something went wrong.
+ */
+static int spi_hid_report_descriptor_request(struct spi_hid *shid)
+{
+	struct device *dev = &shid->spi->dev;
+	struct spi_hid_output_report report = {
+		.report_type = REPORT_DESCRIPTOR,
+		.content_length = 0,
+		.content_id = SPI_HID_OUTPUT_REPORT_CONTENT_ID_DESC_REQUEST,
+		.content = NULL,
+	};
+	int ret;
+
+	ret =  spi_hid_sync_request(shid, &report);
+	if (ret) {
+		dev_err(dev,
+			"Expected report descriptor not received: %d.", ret);
+		return ret;
+	}
+
+	ret = shid->response_length;
+	if (ret != shid->desc.report_descriptor_length) {
+		ret = min_t(unsigned int, ret, shid->desc.report_descriptor_length);
+		dev_err(dev, "Received report descriptor length doesn't match device descriptor field, using min of the two: %d.",
+			ret);
+	}
+
+	return ret;
+}
+
+static int spi_hid_create_device(struct spi_hid *shid)
+{
+	struct hid_device *hid;
+	struct device *dev = &shid->spi->dev;
+	int error;
+
+	hid = hid_allocate_device();
+	error = PTR_ERR_OR_ZERO(hid);
+	if (error) {
+		dev_err(dev, "Failed to allocate hid device: %d.", error);
+		return error;
+	}
+
+	hid->driver_data = shid->spi;
+	hid->ll_driver = &spi_hid_ll_driver;
+	hid->dev.parent = &shid->spi->dev;
+	hid->bus = BUS_SPI;
+	hid->version = shid->desc.hid_version;
+	hid->vendor = shid->desc.vendor_id;
+	hid->product = shid->desc.product_id;
+
+	snprintf(hid->name, sizeof(hid->name), "spi %04X:%04X",
+		 hid->vendor, hid->product);
+	strscpy(hid->phys, dev_name(&shid->spi->dev), sizeof(hid->phys));
+
+	shid->hid = hid;
+
+	error = hid_add_device(hid);
+	if (error) {
+		dev_err(dev, "Failed to add hid device: %d.", error);
+		/*
+		 * We likely got here because report descriptor request timed
+		 * out. Let's disconnect and destroy the hid_device structure.
+		 */
+		spi_hid_stop_hid(shid);
+		return error;
+	}
+
+	return 0;
+}
+
+static int spi_hid_get_request(struct spi_hid *shid, u8 content_id)
+{
+	struct device *dev = &shid->spi->dev;
+	struct spi_hid_output_report report = {
+		.report_type = GET_FEATURE,
+		.content_length = 0,
+		.content_id = content_id,
+		.content = NULL,
+	};
+	int error;
+
+	error = spi_hid_sync_request(shid, &report);
+	if (error) {
+		dev_err(dev,
+			"Expected get request response not received! Error %d.",
+			error);
+		return error;
+	}
+
+	return 0;
+}
+
+static int spi_hid_set_request(struct spi_hid *shid, u8 *arg_buf, u16 arg_len,
+			       u8 content_id)
+{
+	struct spi_hid_output_report report = {
+		.report_type = SET_FEATURE,
+		.content_length = arg_len,
+		.content_id = content_id,
+		.content = arg_buf,
+	};
+
+	return spi_hid_sync_request(shid, &report);
+}
+
+/* This is a placeholder. Will be implemented in the next patch. */
 static irqreturn_t spi_hid_dev_irq(int irq, void *_shid)
 {
 	return IRQ_HANDLED;
 }
 
+static int spi_hid_alloc_buffers(struct spi_hid *shid, size_t report_size)
+{
+	struct device *dev = &shid->spi->dev;
+	int inbufsize = sizeof(shid->input->header) + sizeof(shid->input->body) + report_size;
+	int outbufsize = sizeof(shid->output->header) + report_size;
+
+	// devm_krealloc with __GFP_ZERO ensures the new memory is initialized
+	shid->output = devm_krealloc(dev, shid->output, outbufsize, GFP_KERNEL | __GFP_ZERO);
+	shid->input = devm_krealloc(dev, shid->input, inbufsize, GFP_KERNEL | __GFP_ZERO);
+	shid->response = devm_krealloc(dev, shid->response, inbufsize, GFP_KERNEL | __GFP_ZERO);
+
+	if (!shid->output || !shid->input || !shid->response)
+		return -ENOMEM;
+
+	shid->bufsize = report_size;
+
+	return 0;
+}
+
+static int spi_hid_get_report_length(struct hid_report *report)
+{
+	return ((report->size - 1) >> 3) + 1 +
+		report->device->report_enum[report->type].numbered + 2;
+}
+
+/*
+ * Traverse the supplied list of reports and find the longest
+ */
+static void spi_hid_find_max_report(struct hid_device *hid, u32 type,
+				    u16 *max)
+{
+	struct hid_report *report;
+	u16 size;
+
+	/*
+	 * We should not rely on wMaxInputLength, as some devices may set it to
+	 * a wrong length.
+	 */
+	list_for_each_entry(report, &hid->report_enum[type].report_list, list) {
+		size = spi_hid_get_report_length(report);
+		if (*max < size)
+			*max = size;
+	}
+}
+
+/* hid_ll_driver interface functions */
+
+static int spi_hid_ll_start(struct hid_device *hid)
+{
+	struct spi_device *spi = hid->driver_data;
+	struct spi_hid *shid = spi_get_drvdata(spi);
+	int error = 0;
+	u16 bufsize = 0;
+
+	spi_hid_find_max_report(hid, HID_INPUT_REPORT, &bufsize);
+	spi_hid_find_max_report(hid, HID_OUTPUT_REPORT, &bufsize);
+	spi_hid_find_max_report(hid, HID_FEATURE_REPORT, &bufsize);
+
+	if (bufsize < HID_MIN_BUFFER_SIZE) {
+		dev_err(&spi->dev,
+			"HID_MIN_BUFFER_SIZE > max_input_length (%d).",
+			bufsize);
+		return -EINVAL;
+	}
+
+	if (bufsize > shid->bufsize) {
+		guard(disable_irq)(&shid->spi->irq);
+
+		error = spi_hid_alloc_buffers(shid, bufsize);
+		if (error)
+			return error;
+	}
+
+	return 0;
+}
+
+static void spi_hid_ll_stop(struct hid_device *hid)
+{
+	hid->claimed = 0;
+}
+
+static int spi_hid_ll_open(struct hid_device *hid)
+{
+	struct spi_device *spi = hid->driver_data;
+	struct spi_hid *shid = spi_get_drvdata(spi);
+
+	set_bit(SPI_HID_READY, &shid->flags);
+	return 0;
+}
+
+static void spi_hid_ll_close(struct hid_device *hid)
+{
+	struct spi_device *spi = hid->driver_data;
+	struct spi_hid *shid = spi_get_drvdata(spi);
+
+	clear_bit(SPI_HID_READY, &shid->flags);
+	shid->reset_attempts = 0;
+}
+
+static int spi_hid_ll_power(struct hid_device *hid, int level)
+{
+	struct spi_device *spi = hid->driver_data;
+	struct spi_hid *shid = spi_get_drvdata(spi);
+	int error = 0;
+
+	guard(mutex)(&shid->output_lock);
+	if (!shid->hid)
+		error = -ENODEV;
+
+	return error;
+}
+
+static int spi_hid_ll_parse(struct hid_device *hid)
+{
+	struct spi_device *spi = hid->driver_data;
+	struct spi_hid *shid = spi_get_drvdata(spi);
+	struct device *dev = &spi->dev;
+	int error, len;
+
+	len = spi_hid_report_descriptor_request(shid);
+	if (len < 0) {
+		dev_err(dev, "Report descriptor request failed, %d.", len);
+		return len;
+	}
+
+	/*
+	 * FIXME: below call returning 0 doesn't mean that the report descriptor
+	 * is good. We might be caching a crc32 of a corrupted r. d. or who
+	 * knows what the FW sent. Need to have a feedback loop about r. d.
+	 * being ok and only then cache it.
+	 */
+	error = hid_parse_report(hid, (u8 *)shid->response->content, len);
+	if (error) {
+		dev_err(dev, "failed parsing report: %d.", error);
+		return error;
+	}
+	shid->report_descriptor_crc32 = crc32_le(0,
+						 (unsigned char const *)shid->response->content,
+						 len);
+
+	return 0;
+}
+
+static int spi_hid_ll_raw_request(struct hid_device *hid,
+				  unsigned char reportnum, __u8 *buf,
+				  size_t len, unsigned char rtype, int reqtype)
+{
+	struct spi_device *spi = hid->driver_data;
+	struct spi_hid *shid = spi_get_drvdata(spi);
+	struct device *dev = &spi->dev;
+	int ret;
+
+	switch (reqtype) {
+	case HID_REQ_SET_REPORT:
+		if (buf[0] != reportnum) {
+			dev_err(dev, "report id mismatch.");
+			return -EINVAL;
+		}
+
+		ret = spi_hid_set_request(shid, &buf[1], len - 1,
+					  reportnum);
+		if (ret) {
+			dev_err(dev, "failed to set report.");
+			return ret;
+		}
+
+		ret = len;
+		break;
+	case HID_REQ_GET_REPORT:
+		ret = spi_hid_get_request(shid, reportnum);
+		if (ret) {
+			dev_err(dev, "failed to get report.");
+			return ret;
+		}
+
+		ret = min_t(size_t, len,
+			    (shid->response->body[1] | (shid->response->body[2] << 8)) + 1);
+		buf[0] = shid->response->body[3];
+		memcpy(&buf[1], &shid->response->content, ret);
+		break;
+	default:
+		dev_err(dev, "invalid request type.");
+		return -EIO;
+	}
+
+	return ret;
+}
+
+static int spi_hid_ll_output_report(struct hid_device *hid, __u8 *buf,
+				    size_t len)
+{
+	struct spi_device *spi = hid->driver_data;
+	struct spi_hid *shid = spi_get_drvdata(spi);
+	struct device *dev = &spi->dev;
+	struct spi_hid_output_report report = {
+		.report_type = OUTPUT_REPORT,
+		.content_length = len - 1,
+		.content_id = buf[0],
+		.content = &buf[1],
+	};
+	int error;
+
+	if (!test_bit(SPI_HID_READY, &shid->flags)) {
+		dev_err(dev, "%s called in unready state", __func__);
+		return -ENODEV;
+	}
+
+	if (shid->desc.no_output_report_ack)
+		error = spi_hid_send_output_report(shid, &report);
+	else
+		error = spi_hid_sync_request(shid, &report);
+
+	if (error) {
+		dev_err(dev, "failed to send output report.");
+		return error;
+	}
+
+	return len;
+}
+
+static struct hid_ll_driver spi_hid_ll_driver = {
+	.start = spi_hid_ll_start,
+	.stop = spi_hid_ll_stop,
+	.open = spi_hid_ll_open,
+	.close = spi_hid_ll_close,
+	.power = spi_hid_ll_power,
+	.parse = spi_hid_ll_parse,
+	.output_report = spi_hid_ll_output_report,
+	.raw_request = spi_hid_ll_raw_request,
+};
+
 static ssize_t bus_error_count_show(struct device *dev,
 				    struct device_attribute *attr, char *buf)
 {
@@ -158,6 +664,15 @@ int spi_hid_core_probe(struct spi_device *spi, struct spihid_ops *ops,
 
 	spi_set_drvdata(spi, shid);
 
+	/*
+	 * we need to allocate the buffer without knowing the maximum
+	 * size of the reports. Let's use SZ_2K, then we do the
+	 * real computation later.
+	 */
+	error = spi_hid_alloc_buffers(shid, SZ_2K);
+	if (error)
+		return error;
+
 	/*
 	 * At the end of probe we initialize the device:
 	 *   0) assert reset, bias the interrupt line
@@ -190,6 +705,8 @@ int spi_hid_core_probe(struct spi_device *spi, struct spihid_ops *ops,
 	dev_dbg(dev, "%s: d3 -> %s.", __func__,
 		spi_hid_power_mode_string(shid->power_state));
 
+	spi_hid_create_device(shid);
+
 	return 0;
 }
 EXPORT_SYMBOL_GPL(spi_hid_core_probe);
@@ -200,6 +717,8 @@ void spi_hid_core_remove(struct spi_device *spi)
 	struct device *dev = &spi->dev;
 	int error;
 
+	spi_hid_stop_hid(shid);
+
 	shid->ops->assert_reset(shid->ops);
 	error = shid->ops->power_down(shid->ops);
 	if (error)

-- 
2.53.0.473.g4a7958ca14-goog

[PATCH 05/12] HID: spi-hid: add HID SPI protocol implementation

[Jingyuan Liang]

This driver follows HID Over SPI Protocol Specification 1.0 available at
https://www.microsoft.com/en-us/download/details.aspx?id=103325. The
initial version of the driver does not support: 1) multi-fragment input
reports, 2) sending GET_INPUT and COMMAND output report types and
processing their respective acknowledge input reports, and 3) device
sleep power state.

Signed-off-by: Dmitry Antipov <dmanti@microsoft.com>
Signed-off-by: Angela Czubak <acz@semihalf.com>
Signed-off-by: Jingyuan Liang <jingyliang@chromium.org>
---
 drivers/hid/spi-hid/spi-hid-core.c | 562 ++++++++++++++++++++++++++++++++++++-
 1 file changed, 557 insertions(+), 5 deletions(-)

diff --git a/drivers/hid/spi-hid/spi-hid-core.c b/drivers/hid/spi-hid/spi-hid-core.c
index 18b035324f06..08865d42555f 100644
--- a/drivers/hid/spi-hid/spi-hid-core.c
+++ b/drivers/hid/spi-hid/spi-hid-core.c
@@ -23,11 +23,16 @@
 #include <linux/completion.h>
 #include <linux/crc32.h>
 #include <linux/device.h>
+#include <linux/dma-mapping.h>
 #include <linux/err.h>
 #include <linux/hid.h>
 #include <linux/hid-over-spi.h>
+#include <linux/input.h>
 #include <linux/interrupt.h>
+#include <linux/irq.h>
 #include <linux/jiffies.h>
+#include <linux/kernel.h>
+#include <linux/list.h>
 #include <linux/module.h>
 #include <linux/mutex.h>
 #include <linux/slab.h>
@@ -35,12 +40,22 @@
 #include <linux/string.h>
 #include <linux/sysfs.h>
 #include <linux/unaligned.h>
+#include <linux/wait.h>
+#include <linux/workqueue.h>
+
+/* Protocol constants */
+#define SPI_HID_READ_APPROVAL_CONSTANT		0xff
+#define SPI_HID_INPUT_HEADER_SYNC_BYTE		0x5a
+#define SPI_HID_INPUT_HEADER_VERSION		0x03
+#define SPI_HID_SUPPORTED_VERSION		0x0300
 
 #define SPI_HID_OUTPUT_REPORT_CONTENT_ID_DESC_REQUEST	0x00
 
-#define SPI_HID_RESP_TIMEOUT	1000
+#define SPI_HID_MAX_RESET_ATTEMPTS	3
+#define SPI_HID_RESP_TIMEOUT		1000
 
 /* Protocol message size constants */
+#define SPI_HID_READ_APPROVAL_LEN		5
 #define SPI_HID_OUTPUT_HEADER_LEN		8
 
 /* flags */
@@ -49,6 +64,22 @@
  * requests. The FW becomes ready after sending the report descriptor.
  */
 #define SPI_HID_READY	0
+/*
+ * refresh_in_progress is set to true while the refresh_device worker
+ * thread is destroying and recreating the hidraw device. When this flag
+ * is set to true, the ll_close and ll_open functions will not cause
+ * power state changes.
+ */
+#define SPI_HID_REFRESH_IN_PROGRESS	1
+/*
+ * reset_pending indicates that the device is being reset. When this flag
+ * is set to true, garbage interrupts triggered during reset will be
+ * dropped and will not cause error handling.
+ */
+#define SPI_HID_RESET_PENDING	2
+#define SPI_HID_RESET_RESPONSE	3
+#define SPI_HID_CREATE_DEVICE	4
+#define SPI_HID_ERROR	5
 
 /* Raw input buffer with data from the bus */
 struct spi_hid_input_buf {
@@ -57,6 +88,22 @@ struct spi_hid_input_buf {
 	u8 content[];
 };
 
+/* Processed data from input report header */
+struct spi_hid_input_header {
+	u8 version;
+	u16 report_length;
+	u8 last_fragment_flag;
+	u8 sync_const;
+};
+
+/* Processed data from an input report */
+struct spi_hid_input_report {
+	u8 report_type;
+	u16 content_length;
+	u8 content_id;
+	u8 *content;
+};
+
 /* Raw output report buffer to be put on the bus */
 struct spi_hid_output_buf {
 	u8 header[SPI_HID_OUTPUT_HEADER_LEN];
@@ -113,6 +160,9 @@ struct spi_hid {
 	struct spi_device	*spi;	/* spi device. */
 	struct hid_device	*hid;	/* pointer to corresponding HID dev. */
 
+	struct spi_transfer	input_transfer[2];	/* Transfer buffer for read and write. */
+	struct spi_message	input_message;	/* used to execute a sequence of spi transfers. */
+
 	struct spihid_ops	*ops;
 	struct spi_hid_conf	*conf;
 
@@ -130,10 +180,17 @@ struct spi_hid {
 
 	unsigned long flags;	/* device flags. */
 
+	struct work_struct reset_work;
+
 	/* Control lock to make sure one output transaction at a time. */
 	struct mutex output_lock;
+	/* Power lock to make sure one power state change at a time. */
+	struct mutex power_lock;
 	struct completion output_done;
 
+	u8 read_approval_header[SPI_HID_READ_APPROVAL_LEN];
+	u8 read_approval_body[SPI_HID_READ_APPROVAL_LEN];
+
 	u32 report_descriptor_crc32;	/* HID report descriptor crc32 checksum. */
 
 	u32 regulator_error_count;
@@ -145,6 +202,66 @@ struct spi_hid {
 
 static struct hid_ll_driver spi_hid_ll_driver;
 
+static void spi_hid_populate_read_approvals(const struct spi_hid_conf *conf,
+					    u8 *header_buf, u8 *body_buf)
+{
+	header_buf[0] = conf->read_opcode;
+	put_unaligned_be24(conf->input_report_header_address, &header_buf[1]);
+	header_buf[4] = SPI_HID_READ_APPROVAL_CONSTANT;
+
+	body_buf[0] = conf->read_opcode;
+	put_unaligned_be24(conf->input_report_body_address, &body_buf[1]);
+	body_buf[4] = SPI_HID_READ_APPROVAL_CONSTANT;
+}
+
+static void spi_hid_parse_dev_desc(const struct hidspi_dev_descriptor *raw,
+				   struct spi_hid_device_descriptor *desc)
+{
+	desc->hid_version = le16_to_cpu(raw->bcd_ver);
+	desc->report_descriptor_length = le16_to_cpu(raw->rep_desc_len);
+	desc->max_input_length = le16_to_cpu(raw->max_input_len);
+	desc->max_output_length = le16_to_cpu(raw->max_output_len);
+
+	/* FIXME: multi-fragment not supported, field below not used */
+	desc->max_fragment_length = le16_to_cpu(raw->max_frag_len);
+
+	desc->vendor_id = le16_to_cpu(raw->vendor_id);
+	desc->product_id = le16_to_cpu(raw->product_id);
+	desc->version_id = le16_to_cpu(raw->version_id);
+	desc->no_output_report_ack = le16_to_cpu(raw->flags) & BIT(0);
+}
+
+static void spi_hid_populate_input_header(const u8 *buf,
+					  struct spi_hid_input_header *header)
+{
+	header->version            = buf[0] & 0xf;
+	header->report_length      = (get_unaligned_le16(&buf[1]) & 0x3fff) * 4;
+	header->last_fragment_flag = (buf[2] & 0x40) >> 6;
+	header->sync_const         = buf[3];
+}
+
+static void spi_hid_populate_input_body(const u8 *buf,
+					struct input_report_body_header *body)
+{
+	body->input_report_type = buf[0];
+	body->content_len = get_unaligned_le16(&buf[1]);
+	body->content_id = buf[3];
+}
+
+static void spi_hid_input_report_prepare(struct spi_hid_input_buf *buf,
+					 struct spi_hid_input_report *report)
+{
+	struct spi_hid_input_header header;
+	struct input_report_body_header body;
+
+	spi_hid_populate_input_header(buf->header, &header);
+	spi_hid_populate_input_body(buf->body, &body);
+	report->report_type = body.input_report_type;
+	report->content_length = body.content_len;
+	report->content_id = body.content_id;
+	report->content = buf->content;
+}
+
 static void spi_hid_populate_output_header(u8 *buf,
 					   const struct spi_hid_conf *conf,
 					   const struct spi_hid_output_report *report)
@@ -156,6 +273,33 @@ static void spi_hid_populate_output_header(u8 *buf,
 	buf[7] = report->content_id;
 }
 
+static int spi_hid_input_sync(struct spi_hid *shid, void *buf, u16 length,
+			      bool is_header)
+{
+	int error;
+
+	shid->input_transfer[0].tx_buf = is_header ?
+					 shid->read_approval_header :
+					 shid->read_approval_body;
+	shid->input_transfer[0].len = SPI_HID_READ_APPROVAL_LEN;
+
+	shid->input_transfer[1].rx_buf = buf;
+	shid->input_transfer[1].len = length;
+
+	spi_message_init_with_transfers(&shid->input_message,
+					shid->input_transfer, 2);
+
+	error = spi_sync(shid->spi, &shid->input_message);
+	if (error) {
+		dev_err(&shid->spi->dev, "Error starting sync transfer: %d.", error);
+		shid->bus_error_count++;
+		shid->bus_last_error = error;
+		return error;
+	}
+
+	return 0;
+}
+
 static int spi_hid_output(struct spi_hid *shid, const void *buf, u16 length)
 {
 	int error;
@@ -195,6 +339,50 @@ static void spi_hid_stop_hid(struct spi_hid *shid)
 		hid_destroy_device(hid);
 }
 
+static void spi_hid_error(struct spi_hid *shid)
+{
+	struct device *dev = &shid->spi->dev;
+	int error;
+
+	guard(mutex)(&shid->power_lock);
+	if (shid->power_state == HIDSPI_OFF)
+		return;
+
+	if (shid->reset_attempts++ >= SPI_HID_MAX_RESET_ATTEMPTS) {
+		dev_err(dev, "unresponsive device, aborting.");
+		spi_hid_stop_hid(shid);
+		shid->ops->assert_reset(shid->ops);
+		error = shid->ops->power_down(shid->ops);
+		if (error) {
+			dev_err(dev, "failed to disable regulator.");
+			shid->regulator_error_count++;
+			shid->regulator_last_error = error;
+		}
+		return;
+	}
+
+	clear_bit(SPI_HID_READY, &shid->flags);
+	set_bit(SPI_HID_RESET_PENDING, &shid->flags);
+
+	shid->ops->assert_reset(shid->ops);
+
+	shid->power_state = HIDSPI_OFF;
+
+	/*
+	 * We want to cancel pending reset work as the device is being reset
+	 * to recover from an error. cancel_work_sync will put us in a deadlock
+	 * because this function is scheduled in 'reset_work' and we should
+	 * avoid waiting for itself.
+	 */
+	cancel_work(&shid->reset_work);
+
+	shid->ops->sleep_minimal_reset_delay(shid->ops);
+
+	shid->power_state = HIDSPI_ON;
+
+	shid->ops->deassert_reset(shid->ops);
+}
+
 static int spi_hid_send_output_report(struct spi_hid *shid,
 				      struct spi_hid_output_report *report)
 {
@@ -249,6 +437,86 @@ static int spi_hid_sync_request(struct spi_hid *shid,
 	return 0;
 }
 
+/*
+ * Handle the reset response from the FW by sending a request for the device
+ * descriptor.
+ */
+static void spi_hid_reset_response(struct spi_hid *shid)
+{
+	struct device *dev = &shid->spi->dev;
+	struct spi_hid_output_report report = {
+		.report_type = DEVICE_DESCRIPTOR,
+		.content_length = 0x0,
+		.content_id = SPI_HID_OUTPUT_REPORT_CONTENT_ID_DESC_REQUEST,
+		.content = NULL,
+	};
+	int error;
+
+	if (test_bit(SPI_HID_READY, &shid->flags)) {
+		dev_err(dev, "Spontaneous FW reset!");
+		clear_bit(SPI_HID_READY, &shid->flags);
+		shid->dir_count++;
+	}
+
+	if (shid->power_state == HIDSPI_OFF)
+		return;
+
+	error = spi_hid_sync_request(shid, &report);
+	if (error) {
+		dev_WARN_ONCE(dev, true,
+			      "Failed to send device descriptor request: %d.", error);
+		set_bit(SPI_HID_ERROR, &shid->flags);
+		schedule_work(&shid->reset_work);
+	}
+}
+
+static int spi_hid_input_report_handler(struct spi_hid *shid,
+					struct spi_hid_input_buf *buf)
+{
+	struct device *dev = &shid->spi->dev;
+	struct spi_hid_input_report r;
+	int error = 0;
+
+	if (!test_bit(SPI_HID_READY, &shid->flags) ||
+	    test_bit(SPI_HID_REFRESH_IN_PROGRESS, &shid->flags) || !shid->hid) {
+		dev_err(dev, "HID not ready");
+		return 0;
+	}
+
+	spi_hid_input_report_prepare(buf, &r);
+
+	error = hid_input_report(shid->hid, HID_INPUT_REPORT,
+				 r.content - 1, r.content_length + 1, 1);
+
+	if (error == -ENODEV || error == -EBUSY) {
+		dev_err(dev, "ignoring report --> %d.", error);
+		return 0;
+	} else if (error) {
+		dev_err(dev, "Bad input report: %d.", error);
+	}
+
+	return error;
+}
+
+static void spi_hid_response_handler(struct spi_hid *shid,
+				     struct input_report_body_header *body)
+{
+	shid->response_length = body->content_len;
+	/* completion_done returns 0 if there are waiters, otherwise 1 */
+	if (completion_done(&shid->output_done)) {
+		dev_err(&shid->spi->dev, "Unexpected response report.");
+	} else {
+		if (body->input_report_type == REPORT_DESCRIPTOR_RESPONSE ||
+		    body->input_report_type == GET_FEATURE_RESPONSE) {
+			memcpy(shid->response->body, shid->input->body,
+			       sizeof(shid->input->body));
+			memcpy(shid->response->content, shid->input->content,
+			       body->content_len);
+		}
+		complete(&shid->output_done);
+	}
+}
+
 /*
  * This function returns the length of the report descriptor, or a negative
  * error code if something went wrong.
@@ -268,6 +536,8 @@ static int spi_hid_report_descriptor_request(struct spi_hid *shid)
 	if (ret) {
 		dev_err(dev,
 			"Expected report descriptor not received: %d.", ret);
+		set_bit(SPI_HID_ERROR, &shid->flags);
+		schedule_work(&shid->reset_work);
 		return ret;
 	}
 
@@ -322,6 +592,205 @@ static int spi_hid_create_device(struct spi_hid *shid)
 	return 0;
 }
 
+static void spi_hid_refresh_device(struct spi_hid *shid)
+{
+	struct device *dev = &shid->spi->dev;
+	u32 new_crc32 = 0;
+	int error = 0;
+
+	error = spi_hid_report_descriptor_request(shid);
+	if (error < 0) {
+		dev_err(dev,
+			"%s: failed report descriptor request: %d",
+			__func__, error);
+		return;
+	}
+	new_crc32 = crc32_le(0, (unsigned char const *)shid->response->content,
+			     (size_t)error);
+
+	/* Same report descriptor, so no need to create a new hid device. */
+	if (new_crc32 == shid->report_descriptor_crc32) {
+		set_bit(SPI_HID_READY, &shid->flags);
+		return;
+	}
+
+	shid->report_descriptor_crc32 = new_crc32;
+
+	set_bit(SPI_HID_REFRESH_IN_PROGRESS, &shid->flags);
+
+	spi_hid_stop_hid(shid);
+
+	error = spi_hid_create_device(shid);
+	if (error) {
+		dev_err(dev, "%s: Failed to create hid device: %d.", __func__, error);
+		return;
+	}
+
+	clear_bit(SPI_HID_REFRESH_IN_PROGRESS, &shid->flags);
+}
+
+static void spi_hid_reset_work(struct work_struct *work)
+{
+	struct spi_hid *shid =
+		container_of(work, struct spi_hid, reset_work);
+	struct device *dev = &shid->spi->dev;
+	int error = 0;
+
+	if (test_and_clear_bit(SPI_HID_RESET_RESPONSE, &shid->flags)) {
+		spi_hid_reset_response(shid);
+		return;
+	}
+
+	if (test_and_clear_bit(SPI_HID_CREATE_DEVICE, &shid->flags)) {
+		guard(mutex)(&shid->power_lock);
+		if (shid->power_state == HIDSPI_OFF) {
+			dev_err(dev, "%s: Powered off, returning", __func__);
+			return;
+		}
+
+		if (!shid->hid) {
+			error = spi_hid_create_device(shid);
+			if (error) {
+				dev_err(dev, "%s: Failed to create hid device: %d.",
+					__func__, error);
+				return;
+			}
+		} else {
+			spi_hid_refresh_device(shid);
+		}
+
+		return;
+	}
+
+	if (test_and_clear_bit(SPI_HID_ERROR, &shid->flags)) {
+		spi_hid_error(shid);
+		return;
+	}
+}
+
+static int spi_hid_process_input_report(struct spi_hid *shid,
+					struct spi_hid_input_buf *buf)
+{
+	struct spi_hid_input_header header;
+	struct input_report_body_header body;
+	struct device *dev = &shid->spi->dev;
+	struct hidspi_dev_descriptor *raw;
+
+	spi_hid_populate_input_header(buf->header, &header);
+	spi_hid_populate_input_body(buf->body, &body);
+
+	if (body.content_len > header.report_length) {
+		dev_err(dev, "Bad body length %d > %d.", body.content_len,
+			header.report_length);
+		return -EPROTO;
+	}
+
+	switch (body.input_report_type) {
+	case DATA:
+		return spi_hid_input_report_handler(shid, buf);
+	case RESET_RESPONSE:
+		clear_bit(SPI_HID_RESET_PENDING, &shid->flags);
+		set_bit(SPI_HID_RESET_RESPONSE, &shid->flags);
+		schedule_work(&shid->reset_work);
+		break;
+	case DEVICE_DESCRIPTOR_RESPONSE:
+		/* Mark the completion done to avoid timeout */
+		spi_hid_response_handler(shid, &body);
+
+		/* Reset attempts at every device descriptor fetch */
+		shid->reset_attempts = 0;
+		raw = (struct hidspi_dev_descriptor *)buf->content;
+
+		/* Validate device descriptor length before parsing */
+		if (body.content_len != HIDSPI_DEVICE_DESCRIPTOR_SIZE) {
+			dev_err(dev, "Invalid content length %d, expected %lu.",
+				body.content_len,
+				HIDSPI_DEVICE_DESCRIPTOR_SIZE);
+			return -EPROTO;
+		}
+
+		if (le16_to_cpu(raw->dev_desc_len) !=
+		    HIDSPI_DEVICE_DESCRIPTOR_SIZE) {
+			dev_err(dev,
+				"Invalid wDeviceDescLength %d, expected %lu.",
+				raw->dev_desc_len,
+				HIDSPI_DEVICE_DESCRIPTOR_SIZE);
+			return -EPROTO;
+		}
+
+		spi_hid_parse_dev_desc(raw, &shid->desc);
+
+		if (shid->desc.hid_version != SPI_HID_SUPPORTED_VERSION) {
+			dev_err(dev,
+				"Unsupported device descriptor version %4x.",
+				shid->desc.hid_version);
+			return -EPROTONOSUPPORT;
+		}
+
+		set_bit(SPI_HID_CREATE_DEVICE, &shid->flags);
+		schedule_work(&shid->reset_work);
+
+		break;
+	case OUTPUT_REPORT_RESPONSE:
+		if (shid->desc.no_output_report_ack) {
+			dev_err(dev, "Unexpected output report response.");
+			break;
+		}
+		fallthrough;
+	case GET_FEATURE_RESPONSE:
+	case SET_FEATURE_RESPONSE:
+	case REPORT_DESCRIPTOR_RESPONSE:
+		spi_hid_response_handler(shid, &body);
+		break;
+	/*
+	 * FIXME: sending GET_INPUT and COMMAND reports not supported, thus
+	 * throw away responses to those, they should never come.
+	 */
+	case GET_INPUT_REPORT_RESPONSE:
+	case COMMAND_RESPONSE:
+		dev_err(dev, "Not a supported report type: 0x%x.",
+			body.input_report_type);
+		break;
+	default:
+		dev_err(dev, "Unknown input report: 0x%x.", body.input_report_type);
+		return -EPROTO;
+	}
+
+	return 0;
+}
+
+static int spi_hid_bus_validate_header(struct spi_hid *shid,
+				       struct spi_hid_input_header *header)
+{
+	struct device *dev = &shid->spi->dev;
+
+	if (header->version != SPI_HID_INPUT_HEADER_VERSION) {
+		dev_err(dev, "Unknown input report version (v 0x%x).",
+			header->version);
+		return -EINVAL;
+	}
+
+	if (shid->desc.max_input_length != 0 &&
+	    header->report_length > shid->desc.max_input_length) {
+		dev_err(dev, "Input report body size %u > max expected of %u.",
+			header->report_length, shid->desc.max_input_length);
+		return -EMSGSIZE;
+	}
+
+	if (header->last_fragment_flag != 1) {
+		dev_err(dev, "Multi-fragment reports not supported.");
+		return -EOPNOTSUPP;
+	}
+
+	if (header->sync_const != SPI_HID_INPUT_HEADER_SYNC_BYTE) {
+		dev_err(dev, "Invalid input report sync constant (0x%x).",
+			header->sync_const);
+		return -EINVAL;
+	}
+
+	return 0;
+}
+
 static int spi_hid_get_request(struct spi_hid *shid, u8 content_id)
 {
 	struct device *dev = &shid->spi->dev;
@@ -338,6 +807,8 @@ static int spi_hid_get_request(struct spi_hid *shid, u8 content_id)
 		dev_err(dev,
 			"Expected get request response not received! Error %d.",
 			error);
+		set_bit(SPI_HID_ERROR, &shid->flags);
+		schedule_work(&shid->reset_work);
 		return error;
 	}
 
@@ -357,9 +828,81 @@ static int spi_hid_set_request(struct spi_hid *shid, u8 *arg_buf, u16 arg_len,
 	return spi_hid_sync_request(shid, &report);
 }
 
-/* This is a placeholder. Will be implemented in the next patch. */
 static irqreturn_t spi_hid_dev_irq(int irq, void *_shid)
 {
+	struct spi_hid *shid = _shid;
+	struct device *dev = &shid->spi->dev;
+	struct spi_hid_input_header header;
+	int error = 0;
+
+	error = spi_hid_input_sync(shid, shid->input->header,
+				   sizeof(shid->input->header), true);
+	if (error) {
+		dev_err(dev, "Failed to transfer header: %d.", error);
+		goto err;
+	}
+
+	if (shid->power_state == HIDSPI_OFF) {
+		dev_warn(dev, "Device is off after header was received.");
+		goto out;
+	}
+
+	if (shid->input_message.status < 0) {
+		dev_warn(dev, "Error reading header: %d.",
+			 shid->input_message.status);
+		shid->bus_error_count++;
+		shid->bus_last_error = shid->input_message.status;
+		goto err;
+	}
+
+	spi_hid_populate_input_header(shid->input->header, &header);
+
+	error = spi_hid_bus_validate_header(shid, &header);
+	if (error) {
+		if (!test_bit(SPI_HID_RESET_PENDING, &shid->flags)) {
+			dev_err(dev, "Failed to validate header: %d.", error);
+			print_hex_dump(KERN_ERR, "spi_hid: header buffer: ",
+				       DUMP_PREFIX_NONE, 16, 1, shid->input->header,
+				       sizeof(shid->input->header), false);
+			shid->bus_error_count++;
+			shid->bus_last_error = error;
+			goto err;
+		}
+		goto out;
+	}
+
+	error = spi_hid_input_sync(shid, shid->input->body, header.report_length,
+				   false);
+	if (error) {
+		dev_err(dev, "Failed to transfer body: %d.", error);
+		goto err;
+	}
+
+	if (shid->power_state == HIDSPI_OFF) {
+		dev_warn(dev, "Device is off after body was received.");
+		goto out;
+	}
+
+	if (shid->input_message.status < 0) {
+		dev_warn(dev, "Error reading body: %d.",
+			 shid->input_message.status);
+		shid->bus_error_count++;
+		shid->bus_last_error = shid->input_message.status;
+		goto err;
+	}
+
+	error = spi_hid_process_input_report(shid, shid->input);
+	if (error) {
+		dev_err(dev, "Failed to process input report: %d.", error);
+		goto err;
+	}
+
+out:
+	return IRQ_HANDLED;
+
+err:
+	set_bit(SPI_HID_ERROR, &shid->flags);
+	schedule_work(&shid->reset_work);
 	return IRQ_HANDLED;
 }
 
@@ -661,11 +1204,22 @@ int spi_hid_core_probe(struct spi_device *spi, struct spihid_ops *ops,
 	shid->power_state = HIDSPI_ON;
 	shid->ops = ops;
 	shid->conf = conf;
+	set_bit(SPI_HID_RESET_PENDING, &shid->flags);
 
 	spi_set_drvdata(spi, shid);
 
+	/* Using now populated conf let's pre-calculate the read approvals */
+	spi_hid_populate_read_approvals(shid->conf, shid->read_approval_header,
+					shid->read_approval_body);
+
+	mutex_init(&shid->output_lock);
+	mutex_init(&shid->power_lock);
+	init_completion(&shid->output_done);
+
+	INIT_WORK(&shid->reset_work, spi_hid_reset_work);
+
 	/*
-	 * we need to allocate the buffer without knowing the maximum
+	 * We need to allocate the buffer without knowing the maximum
 	 * size of the reports. Let's use SZ_2K, then we do the
 	 * real computation later.
 	 */
@@ -705,8 +1259,6 @@ int spi_hid_core_probe(struct spi_device *spi, struct spihid_ops *ops,
 	dev_dbg(dev, "%s: d3 -> %s.", __func__,
 		spi_hid_power_mode_string(shid->power_state));
 
-	spi_hid_create_device(shid);
-
 	return 0;
 }
 EXPORT_SYMBOL_GPL(spi_hid_core_probe);

-- 
2.53.0.473.g4a7958ca14-goog

[PATCH 06/12] HID: spi_hid: add spi_hid traces

[Jingyuan Liang]

Add traces for purposed of debugging spi_hid driver.

Signed-off-by: Dmitry Antipov <dmanti@microsoft.com>
Signed-off-by: Angela Czubak <acz@semihalf.com>
Signed-off-by: Jingyuan Liang <jingyliang@chromium.org>
---
 drivers/hid/spi-hid/spi-hid-core.c |  71 -----------------
 drivers/hid/spi-hid/spi-hid-core.h |  83 ++++++++++++++++++++
 include/trace/events/spi_hid.h     | 156 +++++++++++++++++++++++++++++++++++++
 3 files changed, 239 insertions(+), 71 deletions(-)

diff --git a/drivers/hid/spi-hid/spi-hid-core.c b/drivers/hid/spi-hid/spi-hid-core.c
index 08865d42555f..e3273846267e 100644
--- a/drivers/hid/spi-hid/spi-hid-core.c
+++ b/drivers/hid/spi-hid/spi-hid-core.c
@@ -81,13 +81,6 @@
 #define SPI_HID_CREATE_DEVICE	4
 #define SPI_HID_ERROR	5
 
-/* Raw input buffer with data from the bus */
-struct spi_hid_input_buf {
-	u8 header[HIDSPI_INPUT_HEADER_SIZE];
-	u8 body[HIDSPI_INPUT_BODY_HEADER_SIZE];
-	u8 content[];
-};
-
 /* Processed data from input report header */
 struct spi_hid_input_header {
 	u8 version;
@@ -104,12 +97,6 @@ struct spi_hid_input_report {
 	u8 *content;
 };
 
-/* Raw output report buffer to be put on the bus */
-struct spi_hid_output_buf {
-	u8 header[SPI_HID_OUTPUT_HEADER_LEN];
-	u8 content[];
-};
-
 /* Data necessary to send an output report */
 struct spi_hid_output_report {
 	u8 report_type;
@@ -118,19 +105,6 @@ struct spi_hid_output_report {
 	u8 *content;
 };
 
-/* Processed data from a device descriptor */
-struct spi_hid_device_descriptor {
-	u16 hid_version;
-	u16 report_descriptor_length;
-	u16 max_input_length;
-	u16 max_output_length;
-	u16 max_fragment_length;
-	u16 vendor_id;
-	u16 product_id;
-	u16 version_id;
-	u8 no_output_report_ack;
-};
-
 /* struct spi_hid_conf - Conf provided to the core */
 struct spi_hid_conf {
 	u32 input_report_header_address;
@@ -155,51 +129,6 @@ struct spihid_ops {
 	void (*sleep_minimal_reset_delay)(struct spihid_ops *ops);
 };
 
-/* Driver context */
-struct spi_hid {
-	struct spi_device	*spi;	/* spi device. */
-	struct hid_device	*hid;	/* pointer to corresponding HID dev. */
-
-	struct spi_transfer	input_transfer[2];	/* Transfer buffer for read and write. */
-	struct spi_message	input_message;	/* used to execute a sequence of spi transfers. */
-
-	struct spihid_ops	*ops;
-	struct spi_hid_conf	*conf;
-
-	struct spi_hid_device_descriptor desc;	/* HID device descriptor. */
-	struct spi_hid_output_buf *output;	/* Output buffer. */
-	struct spi_hid_input_buf *input;	/* Input buffer. */
-	struct spi_hid_input_buf *response;	/* Response buffer. */
-
-	u16 response_length;
-	u16 bufsize;
-
-	enum hidspi_power_state power_state;
-
-	u8 reset_attempts;	/* The number of reset attempts. */
-
-	unsigned long flags;	/* device flags. */
-
-	struct work_struct reset_work;
-
-	/* Control lock to make sure one output transaction at a time. */
-	struct mutex output_lock;
-	/* Power lock to make sure one power state change at a time. */
-	struct mutex power_lock;
-	struct completion output_done;
-
-	u8 read_approval_header[SPI_HID_READ_APPROVAL_LEN];
-	u8 read_approval_body[SPI_HID_READ_APPROVAL_LEN];
-
-	u32 report_descriptor_crc32;	/* HID report descriptor crc32 checksum. */
-
-	u32 regulator_error_count;
-	int regulator_last_error;
-	u32 bus_error_count;
-	int bus_last_error;
-	u32 dir_count;	/* device initiated reset count. */
-};
-
 static struct hid_ll_driver spi_hid_ll_driver;
 
 static void spi_hid_populate_read_approvals(const struct spi_hid_conf *conf,
diff --git a/drivers/hid/spi-hid/spi-hid-core.h b/drivers/hid/spi-hid/spi-hid-core.h
new file mode 100644
index 000000000000..2bfdfbe6d7fc
--- /dev/null
+++ b/drivers/hid/spi-hid/spi-hid-core.h
@@ -0,0 +1,83 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * Copyright (c) 2021 Microsoft Corporation
+ * Copyright (c) 2026 Google LLC
+ */
+
+#include <linux/hid-over-spi.h>
+#include <linux/spi/spi.h>
+
+/* Protocol message size constants */
+#define SPI_HID_READ_APPROVAL_LEN		5
+#define SPI_HID_OUTPUT_HEADER_LEN		8
+
+/* Raw input buffer with data from the bus */
+struct spi_hid_input_buf {
+	u8 header[HIDSPI_INPUT_HEADER_SIZE];
+	u8 body[HIDSPI_INPUT_BODY_HEADER_SIZE];
+	u8 content[];
+};
+
+/* Raw output report buffer to be put on the bus */
+struct spi_hid_output_buf {
+	u8 header[SPI_HID_OUTPUT_HEADER_LEN];
+	u8 content[];
+};
+
+/* Processed data from a device descriptor */
+struct spi_hid_device_descriptor {
+	u16 hid_version;
+	u16 report_descriptor_length;
+	u16 max_input_length;
+	u16 max_output_length;
+	u16 max_fragment_length;
+	u16 vendor_id;
+	u16 product_id;
+	u16 version_id;
+	u8 no_output_report_ack;
+};
+
+/* Driver context */
+struct spi_hid {
+	struct spi_device	*spi;	/* spi device. */
+	struct hid_device	*hid;	/* pointer to corresponding HID dev. */
+
+	struct spi_transfer	input_transfer[2];	/* Transfer buffer for read and write. */
+	struct spi_message	input_message;	/* used to execute a sequence of spi transfers. */
+
+	struct spihid_ops	*ops;
+	struct spi_hid_conf	*conf;
+
+	struct spi_hid_device_descriptor desc;	/* HID device descriptor. */
+	struct spi_hid_output_buf *output;	/* Output buffer. */
+	struct spi_hid_input_buf *input;	/* Input buffer. */
+	struct spi_hid_input_buf *response;	/* Response buffer. */
+
+	u16 response_length;
+	u16 bufsize;
+
+	enum hidspi_power_state power_state;
+
+	u8 reset_attempts;	/* The number of reset attempts. */
+
+	unsigned long flags;	/* device flags. */
+
+	struct work_struct reset_work;
+
+	/* Control lock to make sure one output transaction at a time. */
+	struct mutex output_lock;
+	/* Power lock to make sure one power state change at a time. */
+	struct mutex power_lock;
+	struct completion output_done;
+
+	u8 read_approval_header[SPI_HID_READ_APPROVAL_LEN];
+	u8 read_approval_body[SPI_HID_READ_APPROVAL_LEN];
+
+	u32 report_descriptor_crc32;	/* HID report descriptor crc32 checksum. */
+
+	u32 regulator_error_count;
+	int regulator_last_error;
+	u32 bus_error_count;
+	int bus_last_error;
+	u32 dir_count;		/* device initiated reset count. */
+};
diff --git a/include/trace/events/spi_hid.h b/include/trace/events/spi_hid.h
new file mode 100644
index 000000000000..e9a579b3806c
--- /dev/null
+++ b/include/trace/events/spi_hid.h
@@ -0,0 +1,156 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * Copyright (c) 2021 Microsoft Corporation
+ */
+
+#undef TRACE_SYSTEM
+#define TRACE_SYSTEM spi_hid
+
+#if !defined(_SPI_HID_TRACE_H) || defined(TRACE_HEADER_MULTI_READ)
+#define _SPI_HID_TRACE_H
+
+#include <linux/types.h>
+#include <linux/tracepoint.h>
+
+DECLARE_EVENT_CLASS(spi_hid_transfer,
+	TP_PROTO(struct spi_hid *shid, const void *tx_buf, int tx_len,
+		 const void *rx_buf, u16 rx_len, int ret),
+
+	TP_ARGS(shid, tx_buf, tx_len, rx_buf, rx_len, ret),
+
+	TP_STRUCT__entry(
+		__field(int, bus_num)
+		__field(int, chip_select)
+		__field(int, ret)
+		__dynamic_array(u8, rx_buf, rx_len)
+		__dynamic_array(u8, tx_buf, tx_len)
+	),
+
+	TP_fast_assign(
+		__entry->bus_num = shid->spi->controller->bus_num;
+		__entry->chip_select = shid->spi->chip_select;
+		__entry->ret = ret;
+
+		memcpy(__get_dynamic_array(tx_buf), tx_buf, tx_len);
+		memcpy(__get_dynamic_array(rx_buf), rx_buf, rx_len);
+	),
+
+	TP_printk("spi%d.%d: len=%d tx=[%*phD] rx=[%*phD] --> %d",
+		  __entry->bus_num, __entry->chip_select,
+		  __get_dynamic_array_len(tx_buf) + __get_dynamic_array_len(rx_buf),
+		  __get_dynamic_array_len(tx_buf), __get_dynamic_array(tx_buf),
+		  __get_dynamic_array_len(rx_buf), __get_dynamic_array(rx_buf),
+		  __entry->ret)
+);
+
+DEFINE_EVENT(spi_hid_transfer, spi_hid_input_sync,
+	     TP_PROTO(struct spi_hid *shid, const void *tx_buf, int tx_len,
+		      const void *rx_buf, u16 rx_len, int ret),
+	     TP_ARGS(shid, tx_buf, tx_len, rx_buf, rx_len, ret));
+
+DEFINE_EVENT(spi_hid_transfer, spi_hid_input_header_complete,
+	     TP_PROTO(struct spi_hid *shid, const void *tx_buf, int tx_len,
+		      const void *rx_buf, u16 rx_len, int ret),
+	     TP_ARGS(shid, tx_buf, tx_len, rx_buf, rx_len, ret));
+
+DEFINE_EVENT(spi_hid_transfer, spi_hid_input_body_complete,
+	     TP_PROTO(struct spi_hid *shid, const void *tx_buf, int tx_len,
+		      const void *rx_buf, u16 rx_len, int ret),
+	     TP_ARGS(shid, tx_buf, tx_len, rx_buf, rx_len, ret));
+
+DECLARE_EVENT_CLASS(spi_hid_irq,
+	TP_PROTO(struct spi_hid *shid, int irq),
+
+	TP_ARGS(shid, irq),
+
+	TP_STRUCT__entry(
+		__field(int, bus_num)
+		__field(int, chip_select)
+		__field(int, irq)
+	),
+
+	TP_fast_assign(
+		__entry->bus_num = shid->spi->controller->bus_num;
+		__entry->chip_select = shid->spi->chip_select;
+		__entry->irq = irq;
+	),
+
+	TP_printk("spi%d.%d: IRQ %d",
+		  __entry->bus_num, __entry->chip_select, __entry->irq)
+);
+
+DEFINE_EVENT(spi_hid_irq, spi_hid_dev_irq,
+	     TP_PROTO(struct spi_hid *shid, int irq), TP_ARGS(shid, irq));
+
+DECLARE_EVENT_CLASS(spi_hid,
+	TP_PROTO(struct spi_hid *shid),
+
+	TP_ARGS(shid),
+
+	TP_STRUCT__entry(
+		__field(int, bus_num)
+		__field(int, chip_select)
+		__field(int, power_state)
+		__field(u32, flags)
+
+		__field(int, vendor_id)
+		__field(int, product_id)
+		__field(int, max_input_length)
+		__field(int, max_output_length)
+		__field(u16, hid_version)
+		__field(u16, report_descriptor_length)
+		__field(u16, version_id)
+	),
+
+	TP_fast_assign(
+		__entry->bus_num = shid->spi->controller->bus_num;
+		__entry->chip_select = shid->spi->chip_select;
+		__entry->power_state = shid->power_state;
+		__entry->flags = shid->flags;
+
+		__entry->vendor_id = shid->desc.vendor_id;
+		__entry->product_id = shid->desc.product_id;
+		__entry->max_input_length = shid->desc.max_input_length;
+		__entry->max_output_length = shid->desc.max_output_length;
+		__entry->hid_version = shid->desc.hid_version;
+		__entry->report_descriptor_length =
+					shid->desc.report_descriptor_length;
+		__entry->version_id = shid->desc.version_id;
+	),
+
+	TP_printk("spi%d.%d: (%04x:%04x v%d) HID v%d.%d state p:%d len i:%d o:%d r:%d flags 0x%08x",
+		  __entry->bus_num, __entry->chip_select,
+		  __entry->vendor_id, __entry->product_id, __entry->version_id,
+		  __entry->hid_version >> 8, __entry->hid_version & 0xff,
+		  __entry->power_state,	__entry->max_input_length,
+		  __entry->max_output_length, __entry->report_descriptor_length,
+		  __entry->flags)
+);
+
+DEFINE_EVENT(spi_hid, spi_hid_header_transfer, TP_PROTO(struct spi_hid *shid),
+	     TP_ARGS(shid));
+
+DEFINE_EVENT(spi_hid, spi_hid_process_input_report,
+	     TP_PROTO(struct spi_hid *shid), TP_ARGS(shid));
+
+DEFINE_EVENT(spi_hid, spi_hid_input_report_handler,
+	     TP_PROTO(struct spi_hid *shid), TP_ARGS(shid));
+
+DEFINE_EVENT(spi_hid, spi_hid_reset_response, TP_PROTO(struct spi_hid *shid),
+	     TP_ARGS(shid));
+
+DEFINE_EVENT(spi_hid, spi_hid_create_device, TP_PROTO(struct spi_hid *shid),
+	     TP_ARGS(shid));
+
+DEFINE_EVENT(spi_hid, spi_hid_refresh_device, TP_PROTO(struct spi_hid *shid),
+	     TP_ARGS(shid));
+
+DEFINE_EVENT(spi_hid, spi_hid_response_handler, TP_PROTO(struct spi_hid *shid),
+	     TP_ARGS(shid));
+
+DEFINE_EVENT(spi_hid, spi_hid_error_handler, TP_PROTO(struct spi_hid *shid),
+	     TP_ARGS(shid));
+
+#endif /* _SPI_HID_TRACE_H */
+
+#include <trace/define_trace.h>

-- 
2.53.0.473.g4a7958ca14-goog

[PATCH 07/12] HID: spi_hid: add ACPI support for SPI over HID

[Jingyuan Liang]

From: Angela Czubak <acz@semihalf.com>

Detect SPI HID devices described in ACPI.

Signed-off-by: Angela Czubak <acz@semihalf.com>
Signed-off-by: Jingyuan Liang <jingyliang@chromium.org>
---
 drivers/hid/spi-hid/Kconfig        |  15 +++
 drivers/hid/spi-hid/Makefile       |   1 +
 drivers/hid/spi-hid/spi-hid-acpi.c | 253 +++++++++++++++++++++++++++++++++++++
 drivers/hid/spi-hid/spi-hid-core.c |  27 +---
 drivers/hid/spi-hid/spi-hid.h      |  44 +++++++
 5 files changed, 316 insertions(+), 24 deletions(-)

diff --git a/drivers/hid/spi-hid/Kconfig b/drivers/hid/spi-hid/Kconfig
index 836fdefe8345..114b1e00da39 100644
--- a/drivers/hid/spi-hid/Kconfig
+++ b/drivers/hid/spi-hid/Kconfig
@@ -10,6 +10,21 @@ menuconfig SPI_HID
 
 if SPI_HID
 
+config SPI_HID_ACPI
+	tristate "HID over SPI transport layer ACPI driver"
+	depends on ACPI
+	select SPI_HID_CORE
+	help
+	  Say Y here if you use a keyboard, a touchpad, a touchscreen, or any
+	  other HID based devices which are connected to your computer via SPI.
+	  This driver supports ACPI-based systems.
+
+	  If unsure, say N.
+
+	  This support is also available as a module.  If so, the module
+	  will be called spi-hid-acpi. It will also build/depend on the
+	  module spi-hid.
+
 config SPI_HID_CORE
 	tristate
 endif
diff --git a/drivers/hid/spi-hid/Makefile b/drivers/hid/spi-hid/Makefile
index 92e24cddbfc2..753c7b7a7844 100644
--- a/drivers/hid/spi-hid/Makefile
+++ b/drivers/hid/spi-hid/Makefile
@@ -7,3 +7,4 @@
 
 obj-$(CONFIG_SPI_HID_CORE)	+= spi-hid.o
 spi-hid-objs 			= spi-hid-core.o
+obj-$(CONFIG_SPI_HID_ACPI)	+= spi-hid-acpi.o
diff --git a/drivers/hid/spi-hid/spi-hid-acpi.c b/drivers/hid/spi-hid/spi-hid-acpi.c
new file mode 100644
index 000000000000..612e74fe72f9
--- /dev/null
+++ b/drivers/hid/spi-hid/spi-hid-acpi.c
@@ -0,0 +1,253 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * HID over SPI protocol, ACPI related code
+ *
+ * Copyright (c) 2021 Microsoft Corporation
+ * Copyright (c) 2026 Google LLC
+ *
+ * This code was forked out of the HID over SPI core code, which is partially
+ * based on "HID over I2C protocol implementation:
+ *
+ * Copyright (c) 2012 Benjamin Tissoires <benjamin.tissoires@gmail.com>
+ * Copyright (c) 2012 Ecole Nationale de l'Aviation Civile, France
+ * Copyright (c) 2012 Red Hat, Inc
+ *
+ * which in turn is partially based on "USB HID support for Linux":
+ *
+ * Copyright (c) 1999 Andreas Gal
+ * Copyright (c) 2000-2005 Vojtech Pavlik <vojtech@suse.cz>
+ * Copyright (c) 2005 Michael Haboustak <mike-@cinci.rr.com> for Concept2, Inc
+ * Copyright (c) 2007-2008 Oliver Neukum
+ * Copyright (c) 2006-2010 Jiri Kosina
+ */
+
+#include <linux/acpi.h>
+#include <linux/delay.h>
+#include <linux/device.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/reset.h>
+#include <linux/uuid.h>
+
+#include "spi-hid.h"
+
+/* Config structure is filled with data from ACPI */
+struct spi_hid_acpi_config {
+	struct spihid_ops ops;
+
+	struct spi_hid_conf property_conf;
+	u32 post_power_on_delay_ms;
+	u32 minimal_reset_delay_ms;
+	struct acpi_device *adev;
+};
+
+/* HID SPI Device: 6e2ac436-0fcf41af-a265-b32a220dcfab */
+static guid_t spi_hid_guid =
+	GUID_INIT(0x6E2AC436, 0x0FCF, 0x41AF,
+		  0xA2, 0x65, 0xB3, 0x2A, 0x22, 0x0D, 0xCF, 0xAB);
+
+static int spi_hid_acpi_populate_config(struct spi_hid_acpi_config *conf,
+					struct acpi_device *adev)
+{
+	acpi_handle handle = acpi_device_handle(adev);
+	union acpi_object *obj;
+
+	conf->adev = adev;
+
+	/* Revision 3 for HID over SPI V1, see specification. */
+	obj = acpi_evaluate_dsm_typed(handle, &spi_hid_guid, 3, 1, NULL,
+				      ACPI_TYPE_INTEGER);
+	if (!obj) {
+		acpi_handle_err(handle,
+				"Error _DSM call to get HID input report header address failed");
+		return -ENODEV;
+	}
+	conf->property_conf.input_report_header_address = obj->integer.value;
+	ACPI_FREE(obj);
+
+	obj = acpi_evaluate_dsm_typed(handle, &spi_hid_guid, 3, 2, NULL,
+				      ACPI_TYPE_INTEGER);
+	if (!obj) {
+		acpi_handle_err(handle,
+				"Error _DSM call to get HID input report body address failed");
+		return -ENODEV;
+	}
+	conf->property_conf.input_report_body_address = obj->integer.value;
+	ACPI_FREE(obj);
+
+	obj = acpi_evaluate_dsm_typed(handle, &spi_hid_guid, 3, 3, NULL,
+				      ACPI_TYPE_INTEGER);
+	if (!obj) {
+		acpi_handle_err(handle,
+				"Error _DSM call to get HID output report header address failed");
+		return -ENODEV;
+	}
+	conf->property_conf.output_report_address = obj->integer.value;
+	ACPI_FREE(obj);
+
+	obj = acpi_evaluate_dsm_typed(handle, &spi_hid_guid, 3, 4, NULL,
+				      ACPI_TYPE_BUFFER);
+	if (!obj) {
+		acpi_handle_err(handle,
+				"Error _DSM call to get HID read opcode failed");
+		return -ENODEV;
+	}
+	if (obj->buffer.length == 1) {
+		conf->property_conf.read_opcode = obj->buffer.pointer[0];
+	} else {
+		acpi_handle_err(handle,
+				"Error _DSM call to get HID read opcode, too long buffer");
+		ACPI_FREE(obj);
+		return -ENODEV;
+	}
+	ACPI_FREE(obj);
+
+	obj = acpi_evaluate_dsm_typed(handle, &spi_hid_guid, 3, 5, NULL,
+				      ACPI_TYPE_BUFFER);
+	if (!obj) {
+		acpi_handle_err(handle,
+				"Error _DSM call to get HID write opcode failed");
+		return -ENODEV;
+	}
+	if (obj->buffer.length == 1) {
+		conf->property_conf.write_opcode = obj->buffer.pointer[0];
+	} else {
+		acpi_handle_err(handle,
+				"Error _DSM call to get HID write opcode, too long buffer");
+		ACPI_FREE(obj);
+		return -ENODEV;
+	}
+	ACPI_FREE(obj);
+
+	/* Value not provided in ACPI,*/
+	conf->post_power_on_delay_ms = 5;
+	conf->minimal_reset_delay_ms = 150;
+
+	if (!acpi_has_method(handle, "_RST")) {
+		acpi_handle_err(handle, "No reset method for acpi handle");
+		return -ENODEV;
+	}
+
+	/* FIXME: not reading hid-over-spi-flags, multi-SPI not supported */
+
+	return 0;
+}
+
+static int spi_hid_acpi_power_none(struct spihid_ops *ops)
+{
+	return 0;
+}
+
+static int spi_hid_acpi_power_down(struct spihid_ops *ops)
+{
+	struct spi_hid_acpi_config *conf = container_of(ops,
+							struct spi_hid_acpi_config,
+							ops);
+
+	return acpi_device_set_power(conf->adev, ACPI_STATE_D3);
+}
+
+static int spi_hid_acpi_power_up(struct spihid_ops *ops)
+{
+	struct spi_hid_acpi_config *conf = container_of(ops,
+							struct spi_hid_acpi_config,
+							ops);
+	int error;
+
+	error = acpi_device_set_power(conf->adev, ACPI_STATE_D0);
+	if (error) {
+		dev_err(&conf->adev->dev, "Error could not power up ACPI device: %d.", error);
+		return error;
+	}
+
+	if (conf->post_power_on_delay_ms)
+		msleep(conf->post_power_on_delay_ms);
+
+	return 0;
+}
+
+static int spi_hid_acpi_assert_reset(struct spihid_ops *ops)
+{
+	return 0;
+}
+
+static int spi_hid_acpi_deassert_reset(struct spihid_ops *ops)
+{
+	struct spi_hid_acpi_config *conf = container_of(ops,
+							struct spi_hid_acpi_config,
+							ops);
+
+	return device_reset(&conf->adev->dev);
+}
+
+static void spi_hid_acpi_sleep_minimal_reset_delay(struct spihid_ops *ops)
+{
+	struct spi_hid_acpi_config *conf = container_of(ops,
+							struct spi_hid_acpi_config,
+							ops);
+	usleep_range(1000 * conf->minimal_reset_delay_ms,
+		     1000 * (conf->minimal_reset_delay_ms + 1));
+}
+
+static int spi_hid_acpi_probe(struct spi_device *spi)
+{
+	struct device *dev = &spi->dev;
+	struct acpi_device *adev;
+	struct spi_hid_acpi_config *config;
+	int error;
+
+	adev = ACPI_COMPANION(dev);
+	if (!adev) {
+		dev_err(dev, "Error could not get ACPI device.");
+		return -ENODEV;
+	}
+
+	config = devm_kzalloc(dev, sizeof(struct spi_hid_acpi_config),
+			      GFP_KERNEL);
+	if (!config)
+		return -ENOMEM;
+
+	if (acpi_device_power_manageable(adev)) {
+		config->ops.power_up = spi_hid_acpi_power_up;
+		config->ops.power_down = spi_hid_acpi_power_down;
+	} else {
+		config->ops.power_up = spi_hid_acpi_power_none;
+		config->ops.power_down = spi_hid_acpi_power_none;
+	}
+	config->ops.assert_reset = spi_hid_acpi_assert_reset;
+	config->ops.deassert_reset = spi_hid_acpi_deassert_reset;
+	config->ops.sleep_minimal_reset_delay =
+		spi_hid_acpi_sleep_minimal_reset_delay;
+
+	error = spi_hid_acpi_populate_config(config, adev);
+	if (error) {
+		dev_err(dev, "%s: unable to populate config data.", __func__);
+		return error;
+	}
+	return spi_hid_core_probe(spi, &config->ops, &config->property_conf);
+}
+
+static const struct acpi_device_id spi_hid_acpi_match[] = {
+	{ "ACPI0C51", 0 },
+	{ "PNP0C51", 0 },
+	{ },
+};
+MODULE_DEVICE_TABLE(acpi, spi_hid_acpi_match);
+
+static struct spi_driver spi_hid_acpi_driver = {
+	.driver = {
+		.name	= "spi_hid_acpi",
+		.owner	= THIS_MODULE,
+		.acpi_match_table = ACPI_PTR(spi_hid_acpi_match),
+		.probe_type = PROBE_PREFER_ASYNCHRONOUS,
+		.dev_groups = spi_hid_groups,
+	},
+	.probe		= spi_hid_acpi_probe,
+	.remove		= spi_hid_core_remove,
+};
+
+module_spi_driver(spi_hid_acpi_driver);
+
+MODULE_DESCRIPTION("HID over SPI ACPI transport driver");
+MODULE_AUTHOR("Angela Czubak <aczubak@google.com>");
+MODULE_LICENSE("GPL");
diff --git a/drivers/hid/spi-hid/spi-hid-core.c b/drivers/hid/spi-hid/spi-hid-core.c
index e3273846267e..02beb209a92d 100644
--- a/drivers/hid/spi-hid/spi-hid-core.c
+++ b/drivers/hid/spi-hid/spi-hid-core.c
@@ -43,6 +43,9 @@
 #include <linux/wait.h>
 #include <linux/workqueue.h>
 
+#include "spi-hid.h"
+#include "spi-hid-core.h"
+
 /* Protocol constants */
 #define SPI_HID_READ_APPROVAL_CONSTANT		0xff
 #define SPI_HID_INPUT_HEADER_SYNC_BYTE		0x5a
@@ -105,30 +108,6 @@ struct spi_hid_output_report {
 	u8 *content;
 };
 
-/* struct spi_hid_conf - Conf provided to the core */
-struct spi_hid_conf {
-	u32 input_report_header_address;
-	u32 input_report_body_address;
-	u32 output_report_address;
-	u8 read_opcode;
-	u8 write_opcode;
-};
-
-/**
- * struct spihid_ops - Ops provided to the core
- * @power_up: do sequencing to power up the device
- * @power_down: do sequencing to power down the device
- * @assert_reset: do sequencing to assert the reset line
- * @deassert_reset: do sequencing to deassert the reset line
- */
-struct spihid_ops {
-	int (*power_up)(struct spihid_ops *ops);
-	int (*power_down)(struct spihid_ops *ops);
-	int (*assert_reset)(struct spihid_ops *ops);
-	int (*deassert_reset)(struct spihid_ops *ops);
-	void (*sleep_minimal_reset_delay)(struct spihid_ops *ops);
-};
-
 static struct hid_ll_driver spi_hid_ll_driver;
 
 static void spi_hid_populate_read_approvals(const struct spi_hid_conf *conf,
diff --git a/drivers/hid/spi-hid/spi-hid.h b/drivers/hid/spi-hid/spi-hid.h
new file mode 100644
index 000000000000..1fdd45262647
--- /dev/null
+++ b/drivers/hid/spi-hid/spi-hid.h
@@ -0,0 +1,44 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * Copyright (c) 2021 Microsoft Corporation
+ * Copyright (c) 2026 Google LLC
+ */
+
+#ifndef SPI_HID_H
+#define SPI_HID_H
+
+#include <linux/spi/spi.h>
+#include <linux/sysfs.h>
+
+/* struct spi_hid_conf - Conf provided to the core */
+struct spi_hid_conf {
+	u32 input_report_header_address;
+	u32 input_report_body_address;
+	u32 output_report_address;
+	u8 read_opcode;
+	u8 write_opcode;
+};
+
+/**
+ * struct spihid_ops - Ops provided to the core
+ * @power_up: do sequencing to power up the device
+ * @power_down: do sequencing to power down the device
+ * @assert_reset: do sequencing to assert the reset line
+ * @deassert_reset: do sequencing to deassert the reset line
+ */
+struct spihid_ops {
+	int (*power_up)(struct spihid_ops *ops);
+	int (*power_down)(struct spihid_ops *ops);
+	int (*assert_reset)(struct spihid_ops *ops);
+	int (*deassert_reset)(struct spihid_ops *ops);
+	void (*sleep_minimal_reset_delay)(struct spihid_ops *ops);
+};
+
+int spi_hid_core_probe(struct spi_device *spi, struct spihid_ops *ops,
+		       struct spi_hid_conf *conf);
+
+void spi_hid_core_remove(struct spi_device *spi);
+
+extern const struct attribute_group *spi_hid_groups[];
+
+#endif /* SPI_HID_H */

-- 
2.53.0.473.g4a7958ca14-goog

[PATCH 08/12] HID: spi_hid: add device tree support for SPI over HID

[Jingyuan Liang]

From: Jarrett Schultz <jaschultz@microsoft.com>

Signed-off-by: Dmitry Antipov <dmanti@microsoft.com>
Signed-off-by: Jingyuan Liang <jingyliang@chromium.org>
---
 drivers/hid/spi-hid/Kconfig      |  15 +++
 drivers/hid/spi-hid/Makefile     |   1 +
 drivers/hid/spi-hid/spi-hid-of.c | 243 +++++++++++++++++++++++++++++++++++++++
 3 files changed, 259 insertions(+)

diff --git a/drivers/hid/spi-hid/Kconfig b/drivers/hid/spi-hid/Kconfig
index 114b1e00da39..76a2cd587a3e 100644
--- a/drivers/hid/spi-hid/Kconfig
+++ b/drivers/hid/spi-hid/Kconfig
@@ -25,6 +25,21 @@ config SPI_HID_ACPI
 	  will be called spi-hid-acpi. It will also build/depend on the
 	  module spi-hid.
 
+config SPI_HID_OF
+	tristate "HID over SPI transport layer Open Firmware driver"
+	depends on OF
+	select SPI_HID_CORE
+	help
+	  Say Y here if you use a keyboard, a touchpad, a touchscreen, or any
+	  other HID based devices which are connected to your computer via SPI.
+	  This driver supports Open Firmware (Device Tree)-based systems.
+
+	  If unsure, say N.
+
+	  This support is also available as a module.  If so, the module
+	  will be called spi-hid-of. It will also build/depend on the
+	  module spi-hid.
+
 config SPI_HID_CORE
 	tristate
 endif
diff --git a/drivers/hid/spi-hid/Makefile b/drivers/hid/spi-hid/Makefile
index 753c7b7a7844..fe627fd378e3 100644
--- a/drivers/hid/spi-hid/Makefile
+++ b/drivers/hid/spi-hid/Makefile
@@ -8,3 +8,4 @@
 obj-$(CONFIG_SPI_HID_CORE)	+= spi-hid.o
 spi-hid-objs 			= spi-hid-core.o
 obj-$(CONFIG_SPI_HID_ACPI)	+= spi-hid-acpi.o
+obj-$(CONFIG_SPI_HID_OF)	+= spi-hid-of.o
diff --git a/drivers/hid/spi-hid/spi-hid-of.c b/drivers/hid/spi-hid/spi-hid-of.c
new file mode 100644
index 000000000000..a20c8146230b
--- /dev/null
+++ b/drivers/hid/spi-hid/spi-hid-of.c
@@ -0,0 +1,243 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * HID over SPI protocol, Open Firmware related code
+ *
+ * Copyright (c) 2021 Microsoft Corporation
+ *
+ * This code was forked out of the HID over SPI core code, which is partially
+ * based on "HID over I2C protocol implementation:
+ *
+ * Copyright (c) 2012 Benjamin Tissoires <benjamin.tissoires@gmail.com>
+ * Copyright (c) 2012 Ecole Nationale de l'Aviation Civile, France
+ * Copyright (c) 2012 Red Hat, Inc
+ *
+ * which in turn is partially based on "USB HID support for Linux":
+ *
+ * Copyright (c) 1999 Andreas Gal
+ * Copyright (c) 2000-2005 Vojtech Pavlik <vojtech@suse.cz>
+ * Copyright (c) 2005 Michael Haboustak <mike-@cinci.rr.com> for Concept2, Inc
+ * Copyright (c) 2007-2008 Oliver Neukum
+ * Copyright (c) 2006-2010 Jiri Kosina
+ */
+
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/regulator/consumer.h>
+#include <linux/gpio/consumer.h>
+#include <linux/delay.h>
+
+#include "spi-hid.h"
+
+/* Config structure is filled with data from Device Tree */
+struct spi_hid_of_config {
+	struct spihid_ops ops;
+
+	struct spi_hid_conf property_conf;
+	u32 post_power_on_delay_ms;
+	u32 minimal_reset_delay_ms;
+	struct gpio_desc *reset_gpio;
+	struct regulator *supply;
+	bool supply_enabled;
+};
+
+static int spi_hid_of_populate_config(struct spi_hid_of_config *conf,
+				      struct device *dev)
+{
+	int error;
+	u32 val;
+
+	error = device_property_read_u32(dev, "input-report-header-address",
+					 &val);
+	if (error) {
+		dev_err(dev, "Input report header address not provided.");
+		return -ENODEV;
+	}
+	conf->property_conf.input_report_header_address = val;
+
+	error = device_property_read_u32(dev, "input-report-body-address", &val);
+	if (error) {
+		dev_err(dev, "Input report body address not provided.");
+		return -ENODEV;
+	}
+	conf->property_conf.input_report_body_address = val;
+
+	error = device_property_read_u32(dev, "output-report-address", &val);
+	if (error) {
+		dev_err(dev, "Output report address not provided.");
+		return -ENODEV;
+	}
+	conf->property_conf.output_report_address = val;
+
+	error = device_property_read_u32(dev, "read-opcode", &val);
+	if (error) {
+		dev_err(dev, "Read opcode not provided.");
+		return -ENODEV;
+	}
+	conf->property_conf.read_opcode = val;
+
+	error = device_property_read_u32(dev, "write-opcode", &val);
+	if (error) {
+		dev_err(dev, "Write opcode not provided.");
+		return -ENODEV;
+	}
+	conf->property_conf.write_opcode = val;
+
+	error = device_property_read_u32(dev, "post-power-on-delay-ms", &val);
+	if (error) {
+		dev_err(dev, "post-power-on-delay-ms not provided, using 10.");
+		val = 10;
+	}
+	conf->post_power_on_delay_ms = val;
+
+	error = device_property_read_u32(dev, "minimal-reset-delay-ms", &val);
+	if (error) {
+		dev_err(dev, "minimal-reset-delay-ms not provided, using 100.");
+		val = 100;
+	}
+	conf->minimal_reset_delay_ms = val;
+
+	/* FIXME: not reading hid-over-spi-flags, multi-fragment not supported */
+
+	conf->supply = devm_regulator_get(dev, "vdd");
+	if (IS_ERR(conf->supply)) {
+		if (PTR_ERR(conf->supply) != -EPROBE_DEFER)
+			dev_err(dev, "Failed to get regulator: %ld.",
+				PTR_ERR(conf->supply));
+		return PTR_ERR(conf->supply);
+	}
+	conf->supply_enabled = false;
+
+	conf->reset_gpio = devm_gpiod_get(dev, "reset", GPIOD_OUT_LOW);
+	if (IS_ERR(conf->reset_gpio)) {
+		dev_err(dev, "%s: error getting reset GPIO.", __func__);
+		return PTR_ERR(conf->reset_gpio);
+	}
+
+	return 0;
+}
+
+static int spi_hid_of_power_down(struct spihid_ops *ops)
+{
+	struct spi_hid_of_config *conf = container_of(ops,
+						      struct spi_hid_of_config,
+						      ops);
+	int error;
+
+	if (!conf->supply_enabled)
+		return 0;
+
+	error = regulator_disable(conf->supply);
+	if (error == 0)
+		conf->supply_enabled = false;
+
+	return error;
+}
+
+static int spi_hid_of_power_up(struct spihid_ops *ops)
+{
+	struct spi_hid_of_config *conf = container_of(ops,
+						      struct spi_hid_of_config,
+						      ops);
+	int error;
+
+	if (conf->supply_enabled)
+		return 0;
+
+	error = regulator_enable(conf->supply);
+
+	if (error == 0) {
+		conf->supply_enabled = true;
+		usleep_range(1000 * conf->post_power_on_delay_ms,
+			     1000 * (conf->post_power_on_delay_ms + 1));
+	}
+
+	return error;
+}
+
+static int spi_hid_of_assert_reset(struct spihid_ops *ops)
+{
+	struct spi_hid_of_config *conf = container_of(ops,
+						      struct spi_hid_of_config,
+						      ops);
+
+	gpiod_set_value(conf->reset_gpio, 1);
+	return 0;
+}
+
+static int spi_hid_of_deassert_reset(struct spihid_ops *ops)
+{
+	struct spi_hid_of_config *conf = container_of(ops,
+						      struct spi_hid_of_config,
+						      ops);
+
+	gpiod_set_value(conf->reset_gpio, 0);
+	return 0;
+}
+
+static void spi_hid_of_sleep_minimal_reset_delay(struct spihid_ops *ops)
+{
+	struct spi_hid_of_config *conf = container_of(ops,
+						      struct spi_hid_of_config,
+						      ops);
+	usleep_range(1000 * conf->minimal_reset_delay_ms,
+		     1000 * (conf->minimal_reset_delay_ms + 1));
+}
+
+static int spi_hid_of_probe(struct spi_device *spi)
+{
+	struct device *dev = &spi->dev;
+	struct spi_hid_of_config *config;
+	int error;
+
+	config = devm_kzalloc(dev, sizeof(struct spi_hid_of_config),
+			      GFP_KERNEL);
+	if (!config)
+		return -ENOMEM;
+
+	config->ops.power_up = spi_hid_of_power_up;
+	config->ops.power_down = spi_hid_of_power_down;
+	config->ops.assert_reset = spi_hid_of_assert_reset;
+	config->ops.deassert_reset = spi_hid_of_deassert_reset;
+	config->ops.sleep_minimal_reset_delay =
+		spi_hid_of_sleep_minimal_reset_delay;
+
+	error = spi_hid_of_populate_config(config, dev);
+	if (error) {
+		dev_err(dev, "%s: unable to populate config data.", __func__);
+		return error;
+	}
+
+	return spi_hid_core_probe(spi, &config->ops, &config->property_conf);
+}
+
+const struct of_device_id spi_hid_of_match[] = {
+	{ .compatible = "hid-over-spi" },
+	{}
+};
+MODULE_DEVICE_TABLE(of, spi_hid_of_match);
+
+static const struct spi_device_id spi_hid_of_id_table[] = {
+	{ "hid", 0 },
+	{ "hid-over-spi", 0 },
+	{ }
+};
+MODULE_DEVICE_TABLE(spi, spi_hid_of_id_table);
+
+static struct spi_driver spi_hid_of_driver = {
+	.driver = {
+		.name	= "spi_hid_of",
+		.owner	= THIS_MODULE,
+		.of_match_table = of_match_ptr(spi_hid_of_match),
+		.probe_type = PROBE_PREFER_ASYNCHRONOUS,
+		.dev_groups = spi_hid_groups,
+	},
+	.probe		= spi_hid_of_probe,
+	.remove		= spi_hid_core_remove,
+	.id_table	= spi_hid_of_id_table,
+};
+
+module_spi_driver(spi_hid_of_driver);
+
+MODULE_DESCRIPTION("HID over SPI OF transport driver");
+MODULE_AUTHOR("Dmitry Antipov <dmanti@microsoft.com>");
+MODULE_LICENSE("GPL");

-- 
2.53.0.473.g4a7958ca14-goog

[PATCH 09/12] dt-bindings: input: Document hid-over-spi DT schema

[Jingyuan Liang]

Documentation describes the required and optional properties for
implementing Device Tree for a Microsoft G6 Touch Digitizer that
supports HID over SPI Protocol 1.0 specification.

The properties are common to HID over SPI.

Signed-off-by: Dmitry Antipov <dmanti@microsoft.com>
Signed-off-by: Jarrett Schultz <jaschultz@microsoft.com>
Signed-off-by: Jingyuan Liang <jingyliang@chromium.org>
---
 .../devicetree/bindings/input/hid-over-spi.yaml    | 153 +++++++++++++++++++++
 1 file changed, 153 insertions(+)

diff --git a/Documentation/devicetree/bindings/input/hid-over-spi.yaml b/Documentation/devicetree/bindings/input/hid-over-spi.yaml
new file mode 100644
index 000000000000..b623629ed9d3
--- /dev/null
+++ b/Documentation/devicetree/bindings/input/hid-over-spi.yaml
@@ -0,0 +1,153 @@
+# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/input/hid-over-spi.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: HID over SPI Devices
+
+maintainers:
+  - Benjamin Tissoires <benjamin.tissoires@redhat.com>
+  - Jiri Kosina <jkosina@suse.cz>
+
+description: |+
+  HID over SPI provides support for various Human Interface Devices over the
+  SPI bus. These devices can be for example touchpads, keyboards, touch screens
+  or sensors.
+
+  The specification has been written by Microsoft and is currently available here:
+  https://www.microsoft.com/en-us/download/details.aspx?id=103325
+
+  If this binding is used, the kernel module spi-hid will handle the communication
+  with the device and the generic hid core layer will handle the protocol.
+
+allOf:
+  - $ref: /schemas/input/touchscreen/touchscreen.yaml#
+
+properties:
+  compatible:
+    oneOf:
+      - items:
+          - enum:
+              - microsoft,g6-touch-digitizer
+          - const: hid-over-spi
+      - description: Just "hid-over-spi" alone is allowed, but not recommended.
+        const: hid-over-spi
+
+  reg:
+    maxItems: 1
+
+  interrupts:
+    maxItems: 1
+
+  reset-gpios:
+    maxItems: 1
+    description:
+      GPIO specifier for the digitizer's reset pin (active low). The line must
+      be flagged with GPIO_ACTIVE_LOW.
+
+  vdd-supply:
+    description:
+      Regulator for the VDD supply voltage.
+
+  input-report-header-address:
+    $ref: /schemas/types.yaml#/definitions/uint32
+    minimum: 0
+    maximum: 0xffffff
+    description:
+      A value to be included in the Read Approval packet, listing an address of
+      the input report header to be put on the SPI bus. This address has 24
+      bits.
+
+  input-report-body-address:
+    $ref: /schemas/types.yaml#/definitions/uint32
+    minimum: 0
+    maximum: 0xffffff
+    description:
+     A value to be included in the Read Approval packet, listing an address of
+      the input report body to be put on the SPI bus. This address has 24 bits.
+
+  output-report-address:
+    $ref: /schemas/types.yaml#/definitions/uint32
+    minimum: 0
+    maximum: 0xffffff
+    description:
+      A value to be included in the Output Report sent by the host, listing an
+      address where the output report on the SPI bus is to be written to. This
+      address has 24 bits.
+
+  post-power-on-delay-ms:
+    description:
+      Optional time in ms required by the device after enabling its regulators
+      or powering it on, before it is ready for communication.
+
+  minimal-reset-delay-ms:
+    description:
+      Optional minimum amount of time in ms that device needs to be in reset
+      state for the reset to take effect.
+
+  read-opcode:
+  $ref: /schemas/types.yaml#/definitions/uint8
+    description:
+      Value to be used in Read Approval packets. 1 byte.
+
+  write-opcode:
+  $ref: /schemas/types.yaml#/definitions/uint8
+    description:
+      Value to be used in Write Approval packets. 1 byte.
+
+  hid-over-spi-flags:
+  $ref: /schemas/types.yaml#/definitions/uint16
+    description:
+      16 bits.
+      Bits 0-12 - Reserved (must be 0)
+      Bit 13 - SPI Write Mode. Possible values -
+        * 0b0- Writes are carried out in Single-SPI mode
+        * 0b1- Writes are carried out in the Multi-SPI mode specified by bits
+               14-15
+      Bits 14-15 - Multi-SPI Mode. Possible values -
+        * 0b00- Single SPI
+        * 0b01- Dual SPI
+        * 0b10- Quad SPI
+
+required:
+  - compatible
+  - interrupts
+  - reset-gpios
+  - vdd-supply
+  - input-report-header-address
+  - input-report-body-address
+  - output-report-address
+  - read-opcode
+  - write-opcode
+  - hid-over-spi-flags
+
+additionalProperties: false
+
+examples:
+  - |
+    #include <dt-bindings/interrupt-controller/irq.h>
+    #include <dt-bindings/gpio/gpio.h>
+
+    spi {
+      #address-cells = <1>;
+      #size-cells = <0>;
+
+      hid@0 {
+        compatible = "hid-over-spi";
+        reg = <0x0>;
+        interrupts-extended = <&gpio 42 IRQ_TYPE_EDGE_FALLING>;
+        reset-gpios = <&gpio 27 GPIO_ACTIVE_LOW>;
+        vdd-supply = <&pm8350c_l3>;
+        pinctrl-names = "default";
+        pinctrl-0 = <&ts_d6_reset_assert &ts_d6_int_bias>;
+        input-report-header-address = <0x1000>;
+        input-report-body-address = <0x1004>;
+        output-report-address = <0x2000>;
+        read-opcode = <0x0b>;
+        write-opcode = <0x02>;
+        hid-over-spi-flags = <0x0000>;
+        post-power-on-delay-ms = <5>;
+        minimal-reset-delay-ms = <5>;
+      };
+    };
\ No newline at end of file

-- 
2.53.0.473.g4a7958ca14-goog

[PATCH 10/12] HID: spi-hid: add power management implementation

[Jingyuan Liang]

Implement HID over SPI driver power management callbacks.

Signed-off-by: Jingyuan Liang <jingyliang@chromium.org>
---
 drivers/hid/spi-hid/spi-hid-acpi.c |   1 +
 drivers/hid/spi-hid/spi-hid-core.c | 107 +++++++++++++++++++++++++++++++++++++
 drivers/hid/spi-hid/spi-hid-of.c   |   1 +
 drivers/hid/spi-hid/spi-hid.h      |   1 +
 4 files changed, 110 insertions(+)

diff --git a/drivers/hid/spi-hid/spi-hid-acpi.c b/drivers/hid/spi-hid/spi-hid-acpi.c
index 612e74fe72f9..2c1e4de99fea 100644
--- a/drivers/hid/spi-hid/spi-hid-acpi.c
+++ b/drivers/hid/spi-hid/spi-hid-acpi.c
@@ -238,6 +238,7 @@ static struct spi_driver spi_hid_acpi_driver = {
 	.driver = {
 		.name	= "spi_hid_acpi",
 		.owner	= THIS_MODULE,
+		.pm	= &spi_hid_core_pm,
 		.acpi_match_table = ACPI_PTR(spi_hid_acpi_match),
 		.probe_type = PROBE_PREFER_ASYNCHRONOUS,
 		.dev_groups = spi_hid_groups,
diff --git a/drivers/hid/spi-hid/spi-hid-core.c b/drivers/hid/spi-hid/spi-hid-core.c
index 02beb209a92d..797ba99394f9 100644
--- a/drivers/hid/spi-hid/spi-hid-core.c
+++ b/drivers/hid/spi-hid/spi-hid-core.c
@@ -35,6 +35,8 @@
 #include <linux/list.h>
 #include <linux/module.h>
 #include <linux/mutex.h>
+#include <linux/pm.h>
+#include <linux/pm_wakeirq.h>
 #include <linux/slab.h>
 #include <linux/spi/spi.h>
 #include <linux/string.h>
@@ -236,6 +238,81 @@ static const char *spi_hid_power_mode_string(enum hidspi_power_state power_state
 	}
 }
 
+static void spi_hid_suspend(struct spi_hid *shid)
+{
+	int error;
+	struct device *dev = &shid->spi->dev;
+
+	guard(mutex)(&shid->power_lock);
+	if (shid->power_state == HIDSPI_OFF)
+		return;
+
+	if (shid->hid) {
+		error = hid_driver_suspend(shid->hid, PMSG_SUSPEND);
+		if (error) {
+			dev_err(dev, "%s failed to suspend hid driver: %d",
+				__func__, error);
+			return;
+		}
+	}
+
+	disable_irq(shid->spi->irq);
+
+	clear_bit(SPI_HID_READY, &shid->flags);
+
+	if (!device_may_wakeup(dev)) {
+		set_bit(SPI_HID_RESET_PENDING, &shid->flags);
+
+		shid->ops->assert_reset(shid->ops);
+
+		error = shid->ops->power_down(shid->ops);
+		if (error) {
+			dev_err(dev, "%s: could not power down.", __func__);
+			shid->regulator_error_count++;
+			shid->regulator_last_error = error;
+			return;
+		}
+
+		shid->power_state = HIDSPI_OFF;
+	}
+}
+
+static void spi_hid_resume(struct spi_hid *shid)
+{
+	int error;
+	struct device *dev = &shid->spi->dev;
+
+	guard(mutex)(&shid->power_lock);
+	if (shid->power_state == HIDSPI_ON)
+		return;
+
+	enable_irq(shid->spi->irq);
+
+	if (!device_may_wakeup(dev)) {
+		shid->ops->assert_reset(shid->ops);
+
+		shid->ops->sleep_minimal_reset_delay(shid->ops);
+
+		error = shid->ops->power_up(shid->ops);
+		if (error) {
+			dev_err(dev, "%s: could not power up.", __func__);
+			shid->regulator_error_count++;
+			shid->regulator_last_error = error;
+			return;
+		}
+		shid->power_state = HIDSPI_ON;
+
+		shid->ops->deassert_reset(shid->ops);
+	}
+
+	if (shid->hid) {
+		error = hid_driver_reset_resume(shid->hid);
+		if (error)
+			dev_err(dev, "%s: failed to reset resume hid driver: %d.",
+				__func__, error);
+	}
+}
+
 static void spi_hid_stop_hid(struct spi_hid *shid)
 {
 	struct hid_device *hid = shid->hid;
@@ -1155,6 +1232,13 @@ int spi_hid_core_probe(struct spi_device *spi, struct spihid_ops *ops,
 		dev_err(dev, "%s: unable to request threaded IRQ.", __func__);
 		return error;
 	}
+	if (device_may_wakeup(dev)) {
+		error = dev_pm_set_wake_irq(dev, spi->irq);
+		if (error) {
+			dev_err(dev, "%s: failed to set wake IRQ.", __func__);
+			return error;
+		}
+	}
 
 	error = shid->ops->power_up(shid->ops);
 	if (error) {
@@ -1186,6 +1270,29 @@ void spi_hid_core_remove(struct spi_device *spi)
 }
 EXPORT_SYMBOL_GPL(spi_hid_core_remove);
 
+static int spi_hid_core_pm_suspend(struct device *dev)
+{
+	struct spi_hid *shid = dev_get_drvdata(dev);
+
+	spi_hid_suspend(shid);
+
+	return 0;
+}
+
+static int spi_hid_core_pm_resume(struct device *dev)
+{
+	struct spi_hid *shid = dev_get_drvdata(dev);
+
+	spi_hid_resume(shid);
+
+	return 0;
+}
+
+const struct dev_pm_ops spi_hid_core_pm = {
+	SYSTEM_SLEEP_PM_OPS(spi_hid_core_pm_suspend, spi_hid_core_pm_resume)
+};
+EXPORT_SYMBOL_GPL(spi_hid_core_pm);
+
 MODULE_DESCRIPTION("HID over SPI transport driver");
 MODULE_AUTHOR("Dmitry Antipov <dmanti@microsoft.com>");
 MODULE_LICENSE("GPL");
diff --git a/drivers/hid/spi-hid/spi-hid-of.c b/drivers/hid/spi-hid/spi-hid-of.c
index a20c8146230b..bc1d3c5a4dda 100644
--- a/drivers/hid/spi-hid/spi-hid-of.c
+++ b/drivers/hid/spi-hid/spi-hid-of.c
@@ -227,6 +227,7 @@ static struct spi_driver spi_hid_of_driver = {
 	.driver = {
 		.name	= "spi_hid_of",
 		.owner	= THIS_MODULE,
+		.pm	= &spi_hid_core_pm,
 		.of_match_table = of_match_ptr(spi_hid_of_match),
 		.probe_type = PROBE_PREFER_ASYNCHRONOUS,
 		.dev_groups = spi_hid_groups,
diff --git a/drivers/hid/spi-hid/spi-hid.h b/drivers/hid/spi-hid/spi-hid.h
index 1fdd45262647..5651c7fb706a 100644
--- a/drivers/hid/spi-hid/spi-hid.h
+++ b/drivers/hid/spi-hid/spi-hid.h
@@ -40,5 +40,6 @@ int spi_hid_core_probe(struct spi_device *spi, struct spihid_ops *ops,
 void spi_hid_core_remove(struct spi_device *spi);
 
 extern const struct attribute_group *spi_hid_groups[];
+extern const struct dev_pm_ops spi_hid_core_pm;
 
 #endif /* SPI_HID_H */

-- 
2.53.0.473.g4a7958ca14-goog

[PATCH 11/12] HID: spi-hid: add panel follower support

[Jingyuan Liang]

Add support to spi-hid to be a panel follower.

Signed-off-by: Jingyuan Liang <jingyliang@chromium.org>
---
 drivers/hid/spi-hid/spi-hid-core.c | 199 +++++++++++++++++++++++++++++--------
 drivers/hid/spi-hid/spi-hid-core.h |   7 ++
 2 files changed, 163 insertions(+), 43 deletions(-)

diff --git a/drivers/hid/spi-hid/spi-hid-core.c b/drivers/hid/spi-hid/spi-hid-core.c
index 797ba99394f9..893a0d4642d2 100644
--- a/drivers/hid/spi-hid/spi-hid-core.c
+++ b/drivers/hid/spi-hid/spi-hid-core.c
@@ -238,21 +238,21 @@ static const char *spi_hid_power_mode_string(enum hidspi_power_state power_state
 	}
 }
 
-static void spi_hid_suspend(struct spi_hid *shid)
+static int spi_hid_suspend(struct spi_hid *shid)
 {
 	int error;
 	struct device *dev = &shid->spi->dev;
 
 	guard(mutex)(&shid->power_lock);
 	if (shid->power_state == HIDSPI_OFF)
-		return;
+		return 0;
 
 	if (shid->hid) {
 		error = hid_driver_suspend(shid->hid, PMSG_SUSPEND);
 		if (error) {
 			dev_err(dev, "%s failed to suspend hid driver: %d",
 				__func__, error);
-			return;
+			return error;
 		}
 	}
 
@@ -270,21 +270,22 @@ static void spi_hid_suspend(struct spi_hid *shid)
 			dev_err(dev, "%s: could not power down.", __func__);
 			shid->regulator_error_count++;
 			shid->regulator_last_error = error;
-			return;
+			return error;
 		}
 
 		shid->power_state = HIDSPI_OFF;
 	}
+	return 0;
 }
 
-static void spi_hid_resume(struct spi_hid *shid)
+static int spi_hid_resume(struct spi_hid *shid)
 {
 	int error;
 	struct device *dev = &shid->spi->dev;
 
 	guard(mutex)(&shid->power_lock);
 	if (shid->power_state == HIDSPI_ON)
-		return;
+		return 0;
 
 	enable_irq(shid->spi->irq);
 
@@ -298,7 +299,7 @@ static void spi_hid_resume(struct spi_hid *shid)
 			dev_err(dev, "%s: could not power up.", __func__);
 			shid->regulator_error_count++;
 			shid->regulator_last_error = error;
-			return;
+			return error;
 		}
 		shid->power_state = HIDSPI_ON;
 
@@ -307,10 +308,13 @@ static void spi_hid_resume(struct spi_hid *shid)
 
 	if (shid->hid) {
 		error = hid_driver_reset_resume(shid->hid);
-		if (error)
+		if (error) {
 			dev_err(dev, "%s: failed to reset resume hid driver: %d.",
 				__func__, error);
+			return error;
+		}
 	}
+	return 0;
 }
 
 static void spi_hid_stop_hid(struct spi_hid *shid)
@@ -1171,6 +1175,132 @@ const struct attribute_group *spi_hid_groups[] = {
 };
 EXPORT_SYMBOL_GPL(spi_hid_groups);
 
+/*
+ * At the end of probe we initialize the device:
+ *   0) assert reset, bias the interrupt line
+ *   1) sleep minimal reset delay
+ *   2) request IRQ
+ *   3) power up the device
+ *   4) deassert reset (high)
+ * After this we expect an IRQ with a reset response.
+ */
+static int spi_hid_dev_init(struct spi_hid *shid)
+{
+	struct spi_device *spi = shid->spi;
+	struct device *dev = &spi->dev;
+	int error;
+
+	shid->ops->assert_reset(shid->ops);
+
+	shid->ops->sleep_minimal_reset_delay(shid->ops);
+
+	error = devm_request_threaded_irq(dev, spi->irq, NULL, spi_hid_dev_irq,
+					  IRQF_ONESHOT, dev_name(&spi->dev), shid);
+	if (error) {
+		dev_err(dev, "%s: unable to request threaded IRQ.", __func__);
+		return error;
+	}
+	if (device_may_wakeup(dev)) {
+		error = dev_pm_set_wake_irq(dev, spi->irq);
+		if (error) {
+			dev_err(dev, "%s: failed to set wake IRQ.", __func__);
+			return error;
+		}
+	}
+
+	error = shid->ops->power_up(shid->ops);
+	if (error) {
+		dev_err(dev, "%s: could not power up.", __func__);
+		shid->regulator_error_count++;
+		shid->regulator_last_error = error;
+		return error;
+	}
+
+	shid->ops->deassert_reset(shid->ops);
+
+	return 0;
+}
+
+static void spi_hid_panel_follower_work(struct work_struct *work)
+{
+	struct spi_hid *shid = container_of(work, struct spi_hid,
+					    panel_follower_work);
+	int error;
+
+	if (!shid->desc.hid_version)
+		error = spi_hid_dev_init(shid);
+	else
+		error = spi_hid_resume(shid);
+	if (error)
+		dev_warn(&shid->spi->dev, "Power on failed: %d", error);
+	else
+		WRITE_ONCE(shid->panel_follower_work_finished, true);
+
+	/*
+	 * The work APIs provide a number of memory ordering guarantees
+	 * including one that says that memory writes before schedule_work()
+	 * are always visible to the work function, but they don't appear to
+	 * guarantee that a write that happened in the work is visible after
+	 * cancel_work_sync(). We'll add a write memory barrier here to match
+	 * with spi_hid_panel_unpreparing() to ensure that our write to
+	 * panel_follower_work_finished is visible there.
+	 */
+	smp_wmb();
+}
+
+static int spi_hid_panel_follower_resume(struct drm_panel_follower *follower)
+{
+	struct spi_hid *shid = container_of(follower, struct spi_hid, panel_follower);
+
+	/*
+	 * Powering on a touchscreen can be a slow process. Queue the work to
+	 * the system workqueue so we don't block the panel's power up.
+	 */
+	WRITE_ONCE(shid->panel_follower_work_finished, false);
+	schedule_work(&shid->panel_follower_work);
+
+	return 0;
+}
+
+static int spi_hid_panel_follower_suspend(struct drm_panel_follower *follower)
+{
+	struct spi_hid *shid = container_of(follower, struct spi_hid, panel_follower);
+
+	cancel_work_sync(&shid->panel_follower_work);
+
+	/* Match with shid_core_panel_follower_work() */
+	smp_rmb();
+	if (!READ_ONCE(shid->panel_follower_work_finished))
+		return 0;
+
+	return spi_hid_suspend(shid);
+}
+
+static const struct drm_panel_follower_funcs
+				spi_hid_panel_follower_prepare_funcs = {
+	.panel_prepared = spi_hid_panel_follower_resume,
+	.panel_unpreparing = spi_hid_panel_follower_suspend,
+};
+
+static int spi_hid_register_panel_follower(struct spi_hid *shid)
+{
+	struct device *dev = &shid->spi->dev;
+
+	shid->panel_follower.funcs = &spi_hid_panel_follower_prepare_funcs;
+
+	/*
+	 * If we're not in control of our own power up/power down then we can't
+	 * do the logic to manage wakeups. Give a warning if a user thought
+	 * that was possible then force the capability off.
+	 */
+	if (device_can_wakeup(dev)) {
+		dev_warn(dev, "Can't wakeup if following panel\n");
+		device_set_wakeup_capable(dev, false);
+	}
+
+	return drm_panel_add_follower(dev, &shid->panel_follower);
+}
+
 int spi_hid_core_probe(struct spi_device *spi, struct spihid_ops *ops,
 		       struct spi_hid_conf *conf)
 {
@@ -1190,6 +1320,7 @@ int spi_hid_core_probe(struct spi_device *spi, struct spihid_ops *ops,
 	shid->ops = ops;
 	shid->conf = conf;
 	set_bit(SPI_HID_RESET_PENDING, &shid->flags);
+	shid->is_panel_follower = drm_is_panel_follower(&spi->dev);
 
 	spi_set_drvdata(spi, shid);
 
@@ -1202,6 +1333,7 @@ int spi_hid_core_probe(struct spi_device *spi, struct spihid_ops *ops,
 	init_completion(&shid->output_done);
 
 	INIT_WORK(&shid->reset_work, spi_hid_reset_work);
+	INIT_WORK(&shid->panel_follower_work, spi_hid_panel_follower_work);
 
 	/*
 	 * We need to allocate the buffer without knowing the maximum
@@ -1212,42 +1344,18 @@ int spi_hid_core_probe(struct spi_device *spi, struct spihid_ops *ops,
 	if (error)
 		return error;
 
-	/*
-	 * At the end of probe we initialize the device:
-	 *   0) assert reset, bias the interrupt line
-	 *   1) sleep minimal reset delay
-	 *   2) request IRQ
-	 *   3) power up the device
-	 *   4) deassert reset (high)
-	 * After this we expect an IRQ with a reset response.
-	 */
-
-	shid->ops->assert_reset(shid->ops);
-
-	shid->ops->sleep_minimal_reset_delay(shid->ops);
-
-	error = devm_request_threaded_irq(dev, spi->irq, NULL, spi_hid_dev_irq,
-					  IRQF_ONESHOT, dev_name(&spi->dev), shid);
-	if (error) {
-		dev_err(dev, "%s: unable to request threaded IRQ.", __func__);
-		return error;
-	}
-	if (device_may_wakeup(dev)) {
-		error = dev_pm_set_wake_irq(dev, spi->irq);
+	if (shid->is_panel_follower) {
+		error = spi_hid_register_panel_follower(shid);
 		if (error) {
-			dev_err(dev, "%s: failed to set wake IRQ.", __func__);
+			dev_err(dev, "%s: could not add panel follower.", __func__);
 			return error;
 		}
+	} else {
+		error = spi_hid_dev_init(shid);
+		if (error)
+			return error;
 	}
 
-	error = shid->ops->power_up(shid->ops);
-	if (error) {
-		dev_err(dev, "%s: could not power up.", __func__);
-		return error;
-	}
-
-	shid->ops->deassert_reset(shid->ops);
-
 	dev_dbg(dev, "%s: d3 -> %s.", __func__,
 		spi_hid_power_mode_string(shid->power_state));
 
@@ -1261,6 +1369,9 @@ void spi_hid_core_remove(struct spi_device *spi)
 	struct device *dev = &spi->dev;
 	int error;
 
+	if (shid->is_panel_follower)
+		drm_panel_remove_follower(&shid->panel_follower);
+
 	spi_hid_stop_hid(shid);
 
 	shid->ops->assert_reset(shid->ops);
@@ -1274,18 +1385,20 @@ static int spi_hid_core_pm_suspend(struct device *dev)
 {
 	struct spi_hid *shid = dev_get_drvdata(dev);
 
-	spi_hid_suspend(shid);
+	if (shid->is_panel_follower)
+		return 0;
 
-	return 0;
+	return spi_hid_suspend(shid);
 }
 
 static int spi_hid_core_pm_resume(struct device *dev)
 {
 	struct spi_hid *shid = dev_get_drvdata(dev);
 
-	spi_hid_resume(shid);
+	if (shid->is_panel_follower)
+		return 0;
 
-	return 0;
+	return spi_hid_resume(shid);
 }
 
 const struct dev_pm_ops spi_hid_core_pm = {
diff --git a/drivers/hid/spi-hid/spi-hid-core.h b/drivers/hid/spi-hid/spi-hid-core.h
index 2bfdfbe6d7fc..88e9020d37aa 100644
--- a/drivers/hid/spi-hid/spi-hid-core.h
+++ b/drivers/hid/spi-hid/spi-hid-core.h
@@ -7,6 +7,8 @@
 #include <linux/hid-over-spi.h>
 #include <linux/spi/spi.h>
 
+#include <drm/drm_panel.h>
+
 /* Protocol message size constants */
 #define SPI_HID_READ_APPROVAL_LEN		5
 #define SPI_HID_OUTPUT_HEADER_LEN		8
@@ -53,6 +55,10 @@ struct spi_hid {
 	struct spi_hid_input_buf *input;	/* Input buffer. */
 	struct spi_hid_input_buf *response;	/* Response buffer. */
 
+	struct drm_panel_follower panel_follower;
+	bool	is_panel_follower;
+	bool	panel_follower_work_finished;
+
 	u16 response_length;
 	u16 bufsize;
 
@@ -63,6 +69,7 @@ struct spi_hid {
 	unsigned long flags;	/* device flags. */
 
 	struct work_struct reset_work;
+	struct work_struct panel_follower_work;
 
 	/* Control lock to make sure one output transaction at a time. */
 	struct mutex output_lock;

-- 
2.53.0.473.g4a7958ca14-goog

[PATCH 12/12] HID: spi-hid: add quirkis to support mode switch for Ilitek touch

[Jingyuan Liang]

Add quirks to support mode switch among Ilitek normal, debug and test mode
and allow delay before send output reports.
Add a shared variable to configure response timeout value for Ilitek
touch controllers.

Signed-off-by: Jingyuan Liang <jingyliang@chromium.org>
---
 drivers/hid/spi-hid/spi-hid-core.c | 84 +++++++++++++++++++++++++++++++++++++-
 drivers/hid/spi-hid/spi-hid-core.h |  4 ++
 drivers/hid/spi-hid/spi-hid.h      |  6 +++
 3 files changed, 93 insertions(+), 1 deletion(-)

diff --git a/drivers/hid/spi-hid/spi-hid-core.c b/drivers/hid/spi-hid/spi-hid-core.c
index 893a0d4642d2..736e51f10cfc 100644
--- a/drivers/hid/spi-hid/spi-hid-core.c
+++ b/drivers/hid/spi-hid/spi-hid-core.c
@@ -22,6 +22,7 @@
 
 #include <linux/completion.h>
 #include <linux/crc32.h>
+#include <linux/delay.h>
 #include <linux/device.h>
 #include <linux/dma-mapping.h>
 #include <linux/err.h>
@@ -45,9 +46,14 @@
 #include <linux/wait.h>
 #include <linux/workqueue.h>
 
+#include "../hid-ids.h"
 #include "spi-hid.h"
 #include "spi-hid-core.h"
 
+/* quirks to control the device */
+#define SPI_HID_QUIRK_MODE_SWITCH	BIT(0)
+#define SPI_HID_QUIRK_READ_DELAY	BIT(1)
+
 /* Protocol constants */
 #define SPI_HID_READ_APPROVAL_CONSTANT		0xff
 #define SPI_HID_INPUT_HEADER_SYNC_BYTE		0x5a
@@ -86,6 +92,16 @@
 #define SPI_HID_CREATE_DEVICE	4
 #define SPI_HID_ERROR	5
 
+static const struct spi_hid_quirks {
+	__u16 idVendor;
+	__u16 idProduct;
+	__u32 quirks;
+} spi_hid_quirks[] = {
+	{ USB_VENDOR_ID_ILITEK, HID_ANY_ID,
+		SPI_HID_QUIRK_MODE_SWITCH | SPI_HID_QUIRK_READ_DELAY },
+	{ 0, 0 }
+};
+
 /* Processed data from input report header */
 struct spi_hid_input_header {
 	u8 version;
@@ -112,6 +128,27 @@ struct spi_hid_output_report {
 
 static struct hid_ll_driver spi_hid_ll_driver;
 
+/**
+ * spi_hid_lookup_quirk: return any quirks associated with a SPI HID device
+ * @idVendor: the 16-bit vendor ID
+ * @idProduct: the 16-bit product ID
+ *
+ * Returns: a u32 quirks value.
+ */
+static u32 spi_hid_lookup_quirk(const u16 idVendor, const u16 idProduct)
+{
+	u32 quirks = 0;
+	int n;
+
+	for (n = 0; spi_hid_quirks[n].idVendor; n++)
+		if (spi_hid_quirks[n].idVendor == idVendor &&
+		    (spi_hid_quirks[n].idProduct == (__u16)HID_ANY_ID ||
+		     spi_hid_quirks[n].idProduct == idProduct))
+			quirks = spi_hid_quirks[n].quirks;
+
+	return quirks;
+}
+
 static void spi_hid_populate_read_approvals(const struct spi_hid_conf *conf,
 					    u8 *header_buf, u8 *body_buf)
 {
@@ -382,6 +419,9 @@ static int spi_hid_send_output_report(struct spi_hid *shid,
 	u8 padding;
 	int error;
 
+	if (shid->quirks & SPI_HID_QUIRK_READ_DELAY)
+		usleep_range(2000, 2100);
+
 	guard(mutex)(&shid->output_lock);
 	if (report->content_length > shid->desc.max_output_length) {
 		dev_err(dev, "Output report too big, content_length 0x%x.",
@@ -406,18 +446,38 @@ static int spi_hid_send_output_report(struct spi_hid *shid,
 	return error;
 }
 
+static const u32 spi_hid_get_timeout(struct spi_hid *shid)
+{
+	struct device *dev = &shid->spi->dev;
+	u32 timeout;
+
+	timeout = READ_ONCE(shid->ops->response_timeout_ms);
+
+	if (timeout < SPI_HID_RESP_TIMEOUT || timeout > 10000) {
+		dev_dbg(dev, "Response timeout is out of range, using default %d",
+			SPI_HID_RESP_TIMEOUT);
+		timeout = SPI_HID_RESP_TIMEOUT;
+	}
+
+	return timeout;
+}
+
 static int spi_hid_sync_request(struct spi_hid *shid,
 				struct spi_hid_output_report *report)
 {
 	struct device *dev = &shid->spi->dev;
+	u32 timeout = SPI_HID_RESP_TIMEOUT;
 	int error;
 
 	error = spi_hid_send_output_report(shid, report);
 	if (error)
 		return error;
 
+	if (shid->quirks & SPI_HID_QUIRK_MODE_SWITCH)
+		timeout = spi_hid_get_timeout(shid);
+
 	error = wait_for_completion_interruptible_timeout(&shid->output_done,
-							  msecs_to_jiffies(SPI_HID_RESP_TIMEOUT));
+							  msecs_to_jiffies(timeout));
 	if (error == 0) {
 		dev_err(dev, "Response timed out.");
 		return -ETIMEDOUT;
@@ -561,6 +621,8 @@ static int spi_hid_create_device(struct spi_hid *shid)
 	hid->vendor = shid->desc.vendor_id;
 	hid->product = shid->desc.product_id;
 
+	shid->quirks = spi_hid_lookup_quirk(hid->vendor, hid->product);
+
 	snprintf(hid->name, sizeof(hid->name), "spi %04X:%04X",
 		 hid->vendor, hid->product);
 	strscpy(hid->phys, dev_name(&shid->spi->dev), sizeof(hid->phys));
@@ -836,6 +898,24 @@ static irqreturn_t spi_hid_dev_irq(int irq, void *_shid)
 		goto out;
 	}
 
+	if (shid->quirks & SPI_HID_QUIRK_MODE_SWITCH) {
+		/*
+		 * Update reset_pending on mode transitions inferred from
+		 * response timeout (entering/exiting a mode).
+		 */
+		u32 timeout = spi_hid_get_timeout(shid);
+		bool mode_enabled = timeout > SPI_HID_RESP_TIMEOUT;
+
+		if (mode_enabled != shid->prev_mode_enabled) {
+			if (mode_enabled)
+				set_bit(SPI_HID_RESET_PENDING, &shid->flags);
+			else
+				clear_bit(SPI_HID_RESET_PENDING, &shid->flags);
+		}
+
+		shid->prev_mode_enabled = mode_enabled;
+	}
+
 	if (shid->input_message.status < 0) {
 		dev_warn(dev, "Error reading header: %d.",
 			 shid->input_message.status);
@@ -1190,6 +1270,8 @@ static int spi_hid_dev_init(struct spi_hid *shid)
 	struct device *dev = &spi->dev;
 	int error;
 
+	shid->ops->custom_init(shid->ops);
+
 	shid->ops->assert_reset(shid->ops);
 
 	shid->ops->sleep_minimal_reset_delay(shid->ops);
diff --git a/drivers/hid/spi-hid/spi-hid-core.h b/drivers/hid/spi-hid/spi-hid-core.h
index 88e9020d37aa..8441dbad95d4 100644
--- a/drivers/hid/spi-hid/spi-hid-core.h
+++ b/drivers/hid/spi-hid/spi-hid-core.h
@@ -62,6 +62,10 @@ struct spi_hid {
 	u16 response_length;
 	u16 bufsize;
 
+	bool prev_mode_enabled;	/* Previous device mode tracked for SPI_HID_QUIRK_MODE_SWITCH. */
+
+	unsigned long quirks;	/* Various quirks. */
+
 	enum hidspi_power_state power_state;
 
 	u8 reset_attempts;	/* The number of reset attempts. */
diff --git a/drivers/hid/spi-hid/spi-hid.h b/drivers/hid/spi-hid/spi-hid.h
index 5651c7fb706a..3c0369bdb4ab 100644
--- a/drivers/hid/spi-hid/spi-hid.h
+++ b/drivers/hid/spi-hid/spi-hid.h
@@ -25,6 +25,9 @@ struct spi_hid_conf {
  * @power_down: do sequencing to power down the device
  * @assert_reset: do sequencing to assert the reset line
  * @deassert_reset: do sequencing to deassert the reset line
+ * @sleep_minimal_reset_delay: minimal sleep delay during reset
+ * @custom_init: customized device init
+ * @response_timeout_ms: output report response timeout in ms
  */
 struct spihid_ops {
 	int (*power_up)(struct spihid_ops *ops);
@@ -32,6 +35,9 @@ struct spihid_ops {
 	int (*assert_reset)(struct spihid_ops *ops);
 	int (*deassert_reset)(struct spihid_ops *ops);
 	void (*sleep_minimal_reset_delay)(struct spihid_ops *ops);
+	int (*custom_init)(struct spihid_ops *ops);
+
+	u32 response_timeout_ms;
 };
 
 int spi_hid_core_probe(struct spi_device *spi, struct spihid_ops *ops,

-- 
2.53.0.473.g4a7958ca14-goog

Re: [PATCH 09/12] dt-bindings: input: Document hid-over-spi DT schema

[Rob Herring (Arm)]

On Tue, 03 Mar 2026 06:13:01 +0000, Jingyuan Liang wrote:
> Documentation describes the required and optional properties for
> implementing Device Tree for a Microsoft G6 Touch Digitizer that
> supports HID over SPI Protocol 1.0 specification.
> 
> The properties are common to HID over SPI.
> 
> Signed-off-by: Dmitry Antipov <dmanti@microsoft.com>
> Signed-off-by: Jarrett Schultz <jaschultz@microsoft.com>
> Signed-off-by: Jingyuan Liang <jingyliang@chromium.org>
> ---
>  .../devicetree/bindings/input/hid-over-spi.yaml    | 153 +++++++++++++++++++++
>  1 file changed, 153 insertions(+)
> 

My bot found errors running 'make dt_binding_check' on your patch:

yamllint warnings/errors:
./Documentation/devicetree/bindings/input/hid-over-spi.yaml:67:6: [warning] wrong indentation: expected 6 but found 5 (indentation)
./Documentation/devicetree/bindings/input/hid-over-spi.yaml:89:15: [error] empty value in block mapping (empty-values)
./Documentation/devicetree/bindings/input/hid-over-spi.yaml:153:7: [error] no new line character at the end of file (new-line-at-end-of-file)
./Documentation/devicetree/bindings/input/hid-over-spi.yaml:91:16: [error] syntax error: mapping values are not allowed here (syntax)

dtschema/dtc warnings/errors:
/builds/robherring/dt-review-ci/linux/Documentation/devicetree/bindings/input/hid-over-spi.yaml: ignoring, error parsing file
./Documentation/devicetree/bindings/input/hid-over-spi.yaml:91:16: mapping values are not allowed here
make[2]: *** Deleting file 'Documentation/devicetree/bindings/input/hid-over-spi.example.dts'
Documentation/devicetree/bindings/input/hid-over-spi.yaml:91:16: mapping values are not allowed here
make[2]: *** [Documentation/devicetree/bindings/Makefile:26: Documentation/devicetree/bindings/input/hid-over-spi.example.dts] Error 1
make[2]: *** Waiting for unfinished jobs....
make[1]: *** [/builds/robherring/dt-review-ci/linux/Makefile:1559: dt_binding_check] Error 2
make: *** [Makefile:248: __sub-make] Error 2

doc reference errors (make refcheckdocs):

See https://patchwork.kernel.org/project/devicetree/patch/20260303-send-upstream-v1-9-1515ba218f3d@chromium.org

The base for the series is generally the latest rc1. A different dependency
should be noted in *this* patch.

If you already ran 'make dt_binding_check' and didn't see the above
error(s), then make sure 'yamllint' is installed and dt-schema is up to
date:

pip3 install dtschema --upgrade

Please check and re-submit after running the above command yourself. Note
that DT_SCHEMA_FILES can be set to your schema file to speed up checking
your schema. However, it must be unset to test all examples with your schema.

Re: [PATCH 09/12] dt-bindings: input: Document hid-over-spi DT schema

[Rob Herring]

On Tue, Mar 3, 2026 at 12:14 AM Jingyuan Liang <jingyliang@chromium.org> wrote:
>
> Documentation describes the required and optional properties for
> implementing Device Tree for a Microsoft G6 Touch Digitizer that
> supports HID over SPI Protocol 1.0 specification.
>
> The properties are common to HID over SPI.
>
> Signed-off-by: Dmitry Antipov <dmanti@microsoft.com>
> Signed-off-by: Jarrett Schultz <jaschultz@microsoft.com>
> Signed-off-by: Jingyuan Liang <jingyliang@chromium.org>
> ---
>  .../devicetree/bindings/input/hid-over-spi.yaml    | 153 +++++++++++++++++++++
>  1 file changed, 153 insertions(+)
>
> diff --git a/Documentation/devicetree/bindings/input/hid-over-spi.yaml b/Documentation/devicetree/bindings/input/hid-over-spi.yaml
> new file mode 100644
> index 000000000000..b623629ed9d3
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/input/hid-over-spi.yaml
> @@ -0,0 +1,153 @@
> +# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
> +%YAML 1.2
> +---
> +$id: http://devicetree.org/schemas/input/hid-over-spi.yaml#
> +$schema: http://devicetree.org/meta-schemas/core.yaml#
> +
> +title: HID over SPI Devices
> +
> +maintainers:
> +  - Benjamin Tissoires <benjamin.tissoires@redhat.com>
> +  - Jiri Kosina <jkosina@suse.cz>
> +
> +description: |+
> +  HID over SPI provides support for various Human Interface Devices over the
> +  SPI bus. These devices can be for example touchpads, keyboards, touch screens
> +  or sensors.
> +
> +  The specification has been written by Microsoft and is currently available here:
> +  https://www.microsoft.com/en-us/download/details.aspx?id=103325
> +
> +  If this binding is used, the kernel module spi-hid will handle the communication
> +  with the device and the generic hid core layer will handle the protocol.
> +
> +allOf:
> +  - $ref: /schemas/input/touchscreen/touchscreen.yaml#
> +
> +properties:
> +  compatible:
> +    oneOf:
> +      - items:
> +          - enum:
> +              - microsoft,g6-touch-digitizer
> +          - const: hid-over-spi
> +      - description: Just "hid-over-spi" alone is allowed, but not recommended.
> +        const: hid-over-spi
> +
> +  reg:
> +    maxItems: 1
> +
> +  interrupts:
> +    maxItems: 1
> +
> +  reset-gpios:
> +    maxItems: 1
> +    description:
> +      GPIO specifier for the digitizer's reset pin (active low). The line must
> +      be flagged with GPIO_ACTIVE_LOW.
> +
> +  vdd-supply:
> +    description:
> +      Regulator for the VDD supply voltage.

Is this part of the spec? This won't scale for multiple devices with
different power rails.

> +
> +  input-report-header-address:
> +    $ref: /schemas/types.yaml#/definitions/uint32
> +    minimum: 0
> +    maximum: 0xffffff
> +    description:
> +      A value to be included in the Read Approval packet, listing an address of
> +      the input report header to be put on the SPI bus. This address has 24
> +      bits.
> +
> +  input-report-body-address:
> +    $ref: /schemas/types.yaml#/definitions/uint32
> +    minimum: 0
> +    maximum: 0xffffff
> +    description:
> +     A value to be included in the Read Approval packet, listing an address of
> +      the input report body to be put on the SPI bus. This address has 24 bits.
> +
> +  output-report-address:
> +    $ref: /schemas/types.yaml#/definitions/uint32
> +    minimum: 0
> +    maximum: 0xffffff
> +    description:
> +      A value to be included in the Output Report sent by the host, listing an
> +      address where the output report on the SPI bus is to be written to. This
> +      address has 24 bits.
> +
> +  post-power-on-delay-ms:
> +    description:
> +      Optional time in ms required by the device after enabling its regulators
> +      or powering it on, before it is ready for communication.

Drop. This should be implied by the compatible.

> +
> +  minimal-reset-delay-ms:
> +    description:
> +      Optional minimum amount of time in ms that device needs to be in reset
> +      state for the reset to take effect.

Drop. This should be implied by the compatible.

> +
> +  read-opcode:
> +  $ref: /schemas/types.yaml#/definitions/uint8
> +    description:
> +      Value to be used in Read Approval packets. 1 byte.
> +
> +  write-opcode:
> +  $ref: /schemas/types.yaml#/definitions/uint8
> +    description:
> +      Value to be used in Write Approval packets. 1 byte.

Why are these and the address properties above not defined by the
spec? Do they vary for a specific device? If not, then they should be
implied by the compatible.

> +
> +  hid-over-spi-flags:
> +  $ref: /schemas/types.yaml#/definitions/uint16
> +    description:
> +      16 bits.
> +      Bits 0-12 - Reserved (must be 0)
> +      Bit 13 - SPI Write Mode. Possible values -
> +        * 0b0- Writes are carried out in Single-SPI mode
> +        * 0b1- Writes are carried out in the Multi-SPI mode specified by bits
> +               14-15
> +      Bits 14-15 - Multi-SPI Mode. Possible values -
> +        * 0b00- Single SPI
> +        * 0b01- Dual SPI
> +        * 0b10- Quad SPI

We already have SPI properties to define the bus width for read and write.

> +
> +required:
> +  - compatible
> +  - interrupts
> +  - reset-gpios
> +  - vdd-supply
> +  - input-report-header-address
> +  - input-report-body-address
> +  - output-report-address
> +  - read-opcode
> +  - write-opcode
> +  - hid-over-spi-flags
> +
> +additionalProperties: false
> +
> +examples:
> +  - |
> +    #include <dt-bindings/interrupt-controller/irq.h>
> +    #include <dt-bindings/gpio/gpio.h>
> +
> +    spi {
> +      #address-cells = <1>;
> +      #size-cells = <0>;
> +
> +      hid@0 {
> +        compatible = "hid-over-spi";
> +        reg = <0x0>;
> +        interrupts-extended = <&gpio 42 IRQ_TYPE_EDGE_FALLING>;
> +        reset-gpios = <&gpio 27 GPIO_ACTIVE_LOW>;
> +        vdd-supply = <&pm8350c_l3>;
> +        pinctrl-names = "default";
> +        pinctrl-0 = <&ts_d6_reset_assert &ts_d6_int_bias>;
> +        input-report-header-address = <0x1000>;
> +        input-report-body-address = <0x1004>;
> +        output-report-address = <0x2000>;
> +        read-opcode = <0x0b>;
> +        write-opcode = <0x02>;
> +        hid-over-spi-flags = <0x0000>;
> +        post-power-on-delay-ms = <5>;
> +        minimal-reset-delay-ms = <5>;
> +      };
> +    };
> \ No newline at end of file

Fix this.

Rob

Re: [PATCH 09/12] dt-bindings: input: Document hid-over-spi DT schema

[Val Packett]

On 3/3/26 3:13 AM, Jingyuan Liang wrote:
> Documentation describes the required and optional properties for
> implementing Device Tree for a Microsoft G6 Touch Digitizer that
> supports HID over SPI Protocol 1.0 specification.
> […]
> +properties:
> +  compatible:
> +    oneOf:
> +      - items:
> +          - enum:
> +              - microsoft,g6-touch-digitizer
> +          - const: hid-over-spi
> +      - description: Just "hid-over-spi" alone is allowed, but not recommended.
> […]
> +required:
> +  - compatible
> +  - interrupts
> +  - reset-gpios

Why is reset required? Is it so implausible on some device implementing 
the spec there wouldn't be a reset gpio?

> +  - vdd-supply
Linux makes up a dummy regulator if DT doesn't provide one, so can 
regulators even be required?
> […]
> +        compatible = "hid-over-spi";
Not following your own recommendation from above :)
> +        reg = <0x0>;
> +        interrupts-extended = <&gpio 42 IRQ_TYPE_EDGE_FALLING>;
> +        reset-gpios = <&gpio 27 GPIO_ACTIVE_LOW>;
> +        vdd-supply = <&pm8350c_l3>;
> +        pinctrl-names = "default";
> +        pinctrl-0 = <&ts_d6_reset_assert &ts_d6_int_bias>;

Heh, "reset_assert" is a name implying it would actually set the value 
from the pinctrl properties, which is what had to be done before 
reset-gpios were supported. But now reset-gpios are supported.


Thanks,
~val


P.S. happy to see work on this happen again!

Re: [PATCH 09/12] dt-bindings: input: Document hid-over-spi DT schema

[Dmitry Torokhov]

On Sat, Mar 07, 2026 at 04:25:44AM -0300, Val Packett wrote:
> 
> On 3/3/26 3:13 AM, Jingyuan Liang wrote:
> > Documentation describes the required and optional properties for
> > implementing Device Tree for a Microsoft G6 Touch Digitizer that
> > supports HID over SPI Protocol 1.0 specification.
> > […]
> > +properties:
> > +  compatible:
> > +    oneOf:
> > +      - items:
> > +          - enum:
> > +              - microsoft,g6-touch-digitizer
> > +          - const: hid-over-spi
> > +      - description: Just "hid-over-spi" alone is allowed, but not recommended.
> > […]
> > +required:
> > +  - compatible
> > +  - interrupts
> > +  - reset-gpios
> 
> Why is reset required? Is it so implausible on some device implementing the
> spec there wouldn't be a reset gpio?

No, because it is mandated by the spec:

"HID SPI peripheral must provide a dedicated reset line, driven by the
HOST, which, when toggled (pulled LOW for at least 10ms, normally HIGH),
will have the effect of resetting the device. If a HID SPI peripheral is
enumerated via ACPI, the device ASL configuration must expose an ACPI
FLDR (_RST) method to control this line."

The spec also states that the host must initiate reset during
initialization of the device.

> 
> > +  - vdd-supply
> Linux makes up a dummy regulator if DT doesn't provide one, so can
> regulators even be required?

There is still a supply line to the chip even if it is not exposed to
the OS control. So as far as chip is concerned the supply is required.

Thanks.

-- 
Dmitry

Re: [PATCH 01/12] Documentation: Correction in HID output_report callback description.

[Dmitry Torokhov]

On Tue, Mar 03, 2026 at 06:12:53AM +0000, Jingyuan Liang wrote:
> From: Jarrett Schultz <jaschultz@microsoft.com>
> 
> Originally output_report callback was described as must-be asynchronous,
> but that is not the case in some implementations, namely i2c-hid.
> Correct the documentation to say that it may be asynchronous.
> 
> Signed-off-by: Dmitry Antipov <dmanti@microsoft.com>
> Signed-off-by: Jingyuan Liang <jingyliang@chromium.org>
> ---
>  Documentation/hid/hid-transport.rst | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/Documentation/hid/hid-transport.rst b/Documentation/hid/hid-transport.rst
> index 6f1692da296c..2008cf432af1 100644
> --- a/Documentation/hid/hid-transport.rst
> +++ b/Documentation/hid/hid-transport.rst
> @@ -327,8 +327,8 @@ The available HID callbacks are:
>  
>     Send raw output report via intr channel. Used by some HID device drivers
>     which require high throughput for outgoing requests on the intr channel. This
> -   must not cause SET_REPORT calls! This must be implemented as asynchronous
> -   output report on the intr channel!
> +   must not cause SET_REPORT calls! This call might be asynchronous, so the
> +   caller should not expect an immediate response!

Reviewed-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>

Thanks.

-- 
Dmitry

Re: [PATCH 02/12] HID: Add BUS_SPI support and define HID_SPI_DEVICE macro

[Dmitry Torokhov]

On Tue, Mar 03, 2026 at 06:12:54AM +0000, Jingyuan Liang wrote:
> From: Jarrett Schultz <jaschultz@microsoft.com>
> 
> If connecting a hid_device with bus field indicating BUS_SPI print out
> "SPI" in the debug print.
> 
> Macro sets the bus field to BUS_SPI and uses arguments to set vendor
> product fields.
> 
> Signed-off-by: Dmitry Antipov <dmanti@microsoft.com>
> Signed-off-by: Jingyuan Liang <jingyliang@chromium.org>
> ---
>  drivers/hid/hid-core.c | 3 +++
>  include/linux/hid.h    | 2 ++
>  2 files changed, 5 insertions(+)
> 
> diff --git a/drivers/hid/hid-core.c b/drivers/hid/hid-core.c
> index a5b3a8ca2fcb..813c9c743ccd 100644
> --- a/drivers/hid/hid-core.c
> +++ b/drivers/hid/hid-core.c
> @@ -2316,6 +2316,9 @@ int hid_connect(struct hid_device *hdev, unsigned int connect_mask)
>  	case BUS_I2C:
>  		bus = "I2C";
>  		break;
> +	case BUS_SPI:
> +		bus = "SPI";
> +		break;
>  	case BUS_SDW:
>  		bus = "SOUNDWIRE";
>  		break;
> diff --git a/include/linux/hid.h b/include/linux/hid.h
> index dce862cafbbd..957f322a0ebd 100644
> --- a/include/linux/hid.h
> +++ b/include/linux/hid.h
> @@ -786,6 +786,8 @@ struct hid_descriptor {
>  	.bus = BUS_BLUETOOTH, .vendor = (ven), .product = (prod)
>  #define HID_I2C_DEVICE(ven, prod)				\
>  	.bus = BUS_I2C, .vendor = (ven), .product = (prod)
> +#define HID_SPI_DEVICE(ven, prod)				\
> +	.bus = BUS_SPI, .vendor = (ven), .product = (prod)
>  
>  #define HID_REPORT_ID(rep) \
>  	.report_type = (rep)

Reviewed-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>

Thanks.

-- 
Dmitry

Re: [PATCH 07/12] HID: spi_hid: add ACPI support for SPI over HID

[Dmitry Torokhov]

On Tue, Mar 03, 2026 at 06:12:59AM +0000, Jingyuan Liang wrote:
> From: Angela Czubak <acz@semihalf.com>
> 
> Detect SPI HID devices described in ACPI.
> 
> Signed-off-by: Angela Czubak <acz@semihalf.com>
> Signed-off-by: Jingyuan Liang <jingyliang@chromium.org>
> ---
>  drivers/hid/spi-hid/Kconfig        |  15 +++
>  drivers/hid/spi-hid/Makefile       |   1 +
>  drivers/hid/spi-hid/spi-hid-acpi.c | 253 +++++++++++++++++++++++++++++++++++++
>  drivers/hid/spi-hid/spi-hid-core.c |  27 +---
>  drivers/hid/spi-hid/spi-hid.h      |  44 +++++++
>  5 files changed, 316 insertions(+), 24 deletions(-)
> 
> diff --git a/drivers/hid/spi-hid/Kconfig b/drivers/hid/spi-hid/Kconfig
> index 836fdefe8345..114b1e00da39 100644
> --- a/drivers/hid/spi-hid/Kconfig
> +++ b/drivers/hid/spi-hid/Kconfig
> @@ -10,6 +10,21 @@ menuconfig SPI_HID
>  
>  if SPI_HID
>  
> +config SPI_HID_ACPI
> +	tristate "HID over SPI transport layer ACPI driver"
> +	depends on ACPI
> +	select SPI_HID_CORE
> +	help
> +	  Say Y here if you use a keyboard, a touchpad, a touchscreen, or any
> +	  other HID based devices which are connected to your computer via SPI.
> +	  This driver supports ACPI-based systems.
> +
> +	  If unsure, say N.
> +
> +	  This support is also available as a module.  If so, the module
> +	  will be called spi-hid-acpi. It will also build/depend on the
> +	  module spi-hid.
> +
>  config SPI_HID_CORE
>  	tristate
>  endif
> diff --git a/drivers/hid/spi-hid/Makefile b/drivers/hid/spi-hid/Makefile
> index 92e24cddbfc2..753c7b7a7844 100644
> --- a/drivers/hid/spi-hid/Makefile
> +++ b/drivers/hid/spi-hid/Makefile
> @@ -7,3 +7,4 @@
>  
>  obj-$(CONFIG_SPI_HID_CORE)	+= spi-hid.o
>  spi-hid-objs 			= spi-hid-core.o
> +obj-$(CONFIG_SPI_HID_ACPI)	+= spi-hid-acpi.o
> diff --git a/drivers/hid/spi-hid/spi-hid-acpi.c b/drivers/hid/spi-hid/spi-hid-acpi.c
> new file mode 100644
> index 000000000000..612e74fe72f9
> --- /dev/null
> +++ b/drivers/hid/spi-hid/spi-hid-acpi.c
> @@ -0,0 +1,253 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/*
> + * HID over SPI protocol, ACPI related code
> + *
> + * Copyright (c) 2021 Microsoft Corporation
> + * Copyright (c) 2026 Google LLC
> + *
> + * This code was forked out of the HID over SPI core code, which is partially
> + * based on "HID over I2C protocol implementation:
> + *
> + * Copyright (c) 2012 Benjamin Tissoires <benjamin.tissoires@gmail.com>
> + * Copyright (c) 2012 Ecole Nationale de l'Aviation Civile, France
> + * Copyright (c) 2012 Red Hat, Inc
> + *
> + * which in turn is partially based on "USB HID support for Linux":
> + *
> + * Copyright (c) 1999 Andreas Gal
> + * Copyright (c) 2000-2005 Vojtech Pavlik <vojtech@suse.cz>
> + * Copyright (c) 2005 Michael Haboustak <mike-@cinci.rr.com> for Concept2, Inc
> + * Copyright (c) 2007-2008 Oliver Neukum
> + * Copyright (c) 2006-2010 Jiri Kosina
> + */
> +
> +#include <linux/acpi.h>
> +#include <linux/delay.h>
> +#include <linux/device.h>
> +#include <linux/kernel.h>
> +#include <linux/module.h>
> +#include <linux/reset.h>
> +#include <linux/uuid.h>
> +
> +#include "spi-hid.h"
> +
> +/* Config structure is filled with data from ACPI */
> +struct spi_hid_acpi_config {
> +	struct spihid_ops ops;
> +
> +	struct spi_hid_conf property_conf;
> +	u32 post_power_on_delay_ms;
> +	u32 minimal_reset_delay_ms;
> +	struct acpi_device *adev;
> +};
> +
> +/* HID SPI Device: 6e2ac436-0fcf41af-a265-b32a220dcfab */
> +static guid_t spi_hid_guid =
> +	GUID_INIT(0x6E2AC436, 0x0FCF, 0x41AF,
> +		  0xA2, 0x65, 0xB3, 0x2A, 0x22, 0x0D, 0xCF, 0xAB);
> +
> +static int spi_hid_acpi_populate_config(struct spi_hid_acpi_config *conf,
> +					struct acpi_device *adev)
> +{
> +	acpi_handle handle = acpi_device_handle(adev);
> +	union acpi_object *obj;
> +
> +	conf->adev = adev;
> +
> +	/* Revision 3 for HID over SPI V1, see specification. */
> +	obj = acpi_evaluate_dsm_typed(handle, &spi_hid_guid, 3, 1, NULL,
> +				      ACPI_TYPE_INTEGER);
> +	if (!obj) {
> +		acpi_handle_err(handle,
> +				"Error _DSM call to get HID input report header address failed");
> +		return -ENODEV;
> +	}
> +	conf->property_conf.input_report_header_address = obj->integer.value;
> +	ACPI_FREE(obj);
> +
> +	obj = acpi_evaluate_dsm_typed(handle, &spi_hid_guid, 3, 2, NULL,
> +				      ACPI_TYPE_INTEGER);
> +	if (!obj) {
> +		acpi_handle_err(handle,
> +				"Error _DSM call to get HID input report body address failed");
> +		return -ENODEV;
> +	}
> +	conf->property_conf.input_report_body_address = obj->integer.value;
> +	ACPI_FREE(obj);
> +
> +	obj = acpi_evaluate_dsm_typed(handle, &spi_hid_guid, 3, 3, NULL,
> +				      ACPI_TYPE_INTEGER);
> +	if (!obj) {
> +		acpi_handle_err(handle,
> +				"Error _DSM call to get HID output report header address failed");
> +		return -ENODEV;
> +	}
> +	conf->property_conf.output_report_address = obj->integer.value;
> +	ACPI_FREE(obj);
> +
> +	obj = acpi_evaluate_dsm_typed(handle, &spi_hid_guid, 3, 4, NULL,
> +				      ACPI_TYPE_BUFFER);
> +	if (!obj) {
> +		acpi_handle_err(handle,
> +				"Error _DSM call to get HID read opcode failed");
> +		return -ENODEV;
> +	}
> +	if (obj->buffer.length == 1) {
> +		conf->property_conf.read_opcode = obj->buffer.pointer[0];
> +	} else {
> +		acpi_handle_err(handle,
> +				"Error _DSM call to get HID read opcode, too long buffer");
> +		ACPI_FREE(obj);
> +		return -ENODEV;
> +	}
> +	ACPI_FREE(obj);
> +
> +	obj = acpi_evaluate_dsm_typed(handle, &spi_hid_guid, 3, 5, NULL,
> +				      ACPI_TYPE_BUFFER);
> +	if (!obj) {
> +		acpi_handle_err(handle,
> +				"Error _DSM call to get HID write opcode failed");
> +		return -ENODEV;
> +	}
> +	if (obj->buffer.length == 1) {
> +		conf->property_conf.write_opcode = obj->buffer.pointer[0];
> +	} else {
> +		acpi_handle_err(handle,
> +				"Error _DSM call to get HID write opcode, too long buffer");
> +		ACPI_FREE(obj);
> +		return -ENODEV;
> +	}
> +	ACPI_FREE(obj);
> +
> +	/* Value not provided in ACPI,*/
> +	conf->post_power_on_delay_ms = 5;
> +	conf->minimal_reset_delay_ms = 150;
> +
> +	if (!acpi_has_method(handle, "_RST")) {
> +		acpi_handle_err(handle, "No reset method for acpi handle");
> +		return -ENODEV;

I would return -EINVAL as we have the device with right _DSM but without
mandated by the spec _RST.

> +	}
> +
> +	/* FIXME: not reading hid-over-spi-flags, multi-SPI not supported */
> +
> +	return 0;
> +}
> +
> +static int spi_hid_acpi_power_none(struct spihid_ops *ops)
> +{
> +	return 0;
> +}
> +
> +static int spi_hid_acpi_power_down(struct spihid_ops *ops)
> +{
> +	struct spi_hid_acpi_config *conf = container_of(ops,
> +							struct spi_hid_acpi_config,
> +							ops);
> +
> +	return acpi_device_set_power(conf->adev, ACPI_STATE_D3);
> +}
> +
> +static int spi_hid_acpi_power_up(struct spihid_ops *ops)
> +{
> +	struct spi_hid_acpi_config *conf = container_of(ops,
> +							struct spi_hid_acpi_config,
> +							ops);
> +	int error;
> +
> +	error = acpi_device_set_power(conf->adev, ACPI_STATE_D0);
> +	if (error) {
> +		dev_err(&conf->adev->dev, "Error could not power up ACPI device: %d.", error);
> +		return error;
> +	}
> +
> +	if (conf->post_power_on_delay_ms)
> +		msleep(conf->post_power_on_delay_ms);
> +
> +	return 0;
> +}
> +
> +static int spi_hid_acpi_assert_reset(struct spihid_ops *ops)
> +{
> +	return 0;
> +}
> +
> +static int spi_hid_acpi_deassert_reset(struct spihid_ops *ops)
> +{
> +	struct spi_hid_acpi_config *conf = container_of(ops,
> +							struct spi_hid_acpi_config,
> +							ops);
> +
> +	return device_reset(&conf->adev->dev);
> +}
> +
> +static void spi_hid_acpi_sleep_minimal_reset_delay(struct spihid_ops *ops)
> +{
> +	struct spi_hid_acpi_config *conf = container_of(ops,
> +							struct spi_hid_acpi_config,
> +							ops);
> +	usleep_range(1000 * conf->minimal_reset_delay_ms,
> +		     1000 * (conf->minimal_reset_delay_ms + 1));

I'd probably use "fsleep(conf->minimal_reset_delay_ms * 1000)".

> +}
> +
> +static int spi_hid_acpi_probe(struct spi_device *spi)
> +{
> +	struct device *dev = &spi->dev;
> +	struct acpi_device *adev;
> +	struct spi_hid_acpi_config *config;
> +	int error;
> +
> +	adev = ACPI_COMPANION(dev);
> +	if (!adev) {
> +		dev_err(dev, "Error could not get ACPI device.");
> +		return -ENODEV;
> +	}
> +
> +	config = devm_kzalloc(dev, sizeof(struct spi_hid_acpi_config),
> +			      GFP_KERNEL);
> +	if (!config)
> +		return -ENOMEM;
> +
> +	if (acpi_device_power_manageable(adev)) {
> +		config->ops.power_up = spi_hid_acpi_power_up;
> +		config->ops.power_down = spi_hid_acpi_power_down;
> +	} else {
> +		config->ops.power_up = spi_hid_acpi_power_none;
> +		config->ops.power_down = spi_hid_acpi_power_none;
> +	}
> +	config->ops.assert_reset = spi_hid_acpi_assert_reset;
> +	config->ops.deassert_reset = spi_hid_acpi_deassert_reset;
> +	config->ops.sleep_minimal_reset_delay =
> +		spi_hid_acpi_sleep_minimal_reset_delay;
> +
> +	error = spi_hid_acpi_populate_config(config, adev);
> +	if (error) {
> +		dev_err(dev, "%s: unable to populate config data.", __func__);
> +		return error;
> +	}

I would add a blank line.

> +	return spi_hid_core_probe(spi, &config->ops, &config->property_conf);
> +}
> +
> +static const struct acpi_device_id spi_hid_acpi_match[] = {
> +	{ "ACPI0C51", 0 },
> +	{ "PNP0C51", 0 },
> +	{ },

No comma on sentinels.

> +};
> +MODULE_DEVICE_TABLE(acpi, spi_hid_acpi_match);
> +
> +static struct spi_driver spi_hid_acpi_driver = {
> +	.driver = {
> +		.name	= "spi_hid_acpi",
> +		.owner	= THIS_MODULE,
> +		.acpi_match_table = ACPI_PTR(spi_hid_acpi_match),

This is dependent on ACPI, so no need to sue ACPI_PTR().

> +		.probe_type = PROBE_PREFER_ASYNCHRONOUS,
> +		.dev_groups = spi_hid_groups,
> +	},
> +	.probe		= spi_hid_acpi_probe,
> +	.remove		= spi_hid_core_remove,
> +};
> +
> +module_spi_driver(spi_hid_acpi_driver);
> +
> +MODULE_DESCRIPTION("HID over SPI ACPI transport driver");
> +MODULE_AUTHOR("Angela Czubak <aczubak@google.com>");
> +MODULE_LICENSE("GPL");
> diff --git a/drivers/hid/spi-hid/spi-hid-core.c b/drivers/hid/spi-hid/spi-hid-core.c
> index e3273846267e..02beb209a92d 100644
> --- a/drivers/hid/spi-hid/spi-hid-core.c
> +++ b/drivers/hid/spi-hid/spi-hid-core.c
> @@ -43,6 +43,9 @@
>  #include <linux/wait.h>
>  #include <linux/workqueue.h>
>  
> +#include "spi-hid.h"
> +#include "spi-hid-core.h"
> +
>  /* Protocol constants */
>  #define SPI_HID_READ_APPROVAL_CONSTANT		0xff
>  #define SPI_HID_INPUT_HEADER_SYNC_BYTE		0x5a
> @@ -105,30 +108,6 @@ struct spi_hid_output_report {
>  	u8 *content;
>  };
>  
> -/* struct spi_hid_conf - Conf provided to the core */
> -struct spi_hid_conf {
> -	u32 input_report_header_address;
> -	u32 input_report_body_address;
> -	u32 output_report_address;
> -	u8 read_opcode;
> -	u8 write_opcode;
> -};
> -
> -/**
> - * struct spihid_ops - Ops provided to the core
> - * @power_up: do sequencing to power up the device
> - * @power_down: do sequencing to power down the device
> - * @assert_reset: do sequencing to assert the reset line
> - * @deassert_reset: do sequencing to deassert the reset line
> - */
> -struct spihid_ops {
> -	int (*power_up)(struct spihid_ops *ops);
> -	int (*power_down)(struct spihid_ops *ops);
> -	int (*assert_reset)(struct spihid_ops *ops);
> -	int (*deassert_reset)(struct spihid_ops *ops);
> -	void (*sleep_minimal_reset_delay)(struct spihid_ops *ops);
> -};
> -
>  static struct hid_ll_driver spi_hid_ll_driver;
>  
>  static void spi_hid_populate_read_approvals(const struct spi_hid_conf *conf,
> diff --git a/drivers/hid/spi-hid/spi-hid.h b/drivers/hid/spi-hid/spi-hid.h
> new file mode 100644
> index 000000000000..1fdd45262647
> --- /dev/null
> +++ b/drivers/hid/spi-hid/spi-hid.h
> @@ -0,0 +1,44 @@
> +/* SPDX-License-Identifier: GPL-2.0 */
> +/*
> + * Copyright (c) 2021 Microsoft Corporation
> + * Copyright (c) 2026 Google LLC
> + */
> +
> +#ifndef SPI_HID_H
> +#define SPI_HID_H
> +
> +#include <linux/spi/spi.h>
> +#include <linux/sysfs.h>
> +
> +/* struct spi_hid_conf - Conf provided to the core */
> +struct spi_hid_conf {
> +	u32 input_report_header_address;
> +	u32 input_report_body_address;
> +	u32 output_report_address;
> +	u8 read_opcode;
> +	u8 write_opcode;
> +};
> +
> +/**
> + * struct spihid_ops - Ops provided to the core
> + * @power_up: do sequencing to power up the device
> + * @power_down: do sequencing to power down the device
> + * @assert_reset: do sequencing to assert the reset line
> + * @deassert_reset: do sequencing to deassert the reset line
> + */
> +struct spihid_ops {
> +	int (*power_up)(struct spihid_ops *ops);
> +	int (*power_down)(struct spihid_ops *ops);
> +	int (*assert_reset)(struct spihid_ops *ops);
> +	int (*deassert_reset)(struct spihid_ops *ops);
> +	void (*sleep_minimal_reset_delay)(struct spihid_ops *ops);
> +};
> +
> +int spi_hid_core_probe(struct spi_device *spi, struct spihid_ops *ops,
> +		       struct spi_hid_conf *conf);
> +
> +void spi_hid_core_remove(struct spi_device *spi);
> +
> +extern const struct attribute_group *spi_hid_groups[];
> +
> +#endif /* SPI_HID_H */

I am not sure if this belongs to this patch or if it should be better in
the patch introducing the main driver from the beginning.

For the ACPI part:

Reviewed-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>

Thanks.

-- 
Dmitry

Fwd: [PATCH 09/12] dt-bindings: input: Document hid-over-spi DT schema

[Jingyuan Liang]

(Resending to the list. Apologies, I accidentally dropped the CCs on
my initial reply!)

On Tue, Mar 3, 2026 at 5:53 AM Rob Herring <robh@kernel.org> wrote:
>
> On Tue, Mar 3, 2026 at 12:14 AM Jingyuan Liang <jingyliang@chromium.org> wrote:
> >
> > Documentation describes the required and optional properties for
> > implementing Device Tree for a Microsoft G6 Touch Digitizer that
> > supports HID over SPI Protocol 1.0 specification.
> >
> > The properties are common to HID over SPI.
> >
> > Signed-off-by: Dmitry Antipov <dmanti@microsoft.com>
> > Signed-off-by: Jarrett Schultz <jaschultz@microsoft.com>
> > Signed-off-by: Jingyuan Liang <jingyliang@chromium.org>
> > ---
> >  .../devicetree/bindings/input/hid-over-spi.yaml    | 153 +++++++++++++++++++++
> >  1 file changed, 153 insertions(+)
> >
> > diff --git a/Documentation/devicetree/bindings/input/hid-over-spi.yaml b/Documentation/devicetree/bindings/input/hid-over-spi.yaml
> > new file mode 100644
> > index 000000000000..b623629ed9d3
> > --- /dev/null
> > +++ b/Documentation/devicetree/bindings/input/hid-over-spi.yaml
> > @@ -0,0 +1,153 @@
> > +# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
> > +%YAML 1.2
> > +---
> > +$id: http://devicetree.org/schemas/input/hid-over-spi.yaml#
> > +$schema: http://devicetree.org/meta-schemas/core.yaml#
> > +
> > +title: HID over SPI Devices
> > +
> > +maintainers:
> > +  - Benjamin Tissoires <benjamin.tissoires@redhat.com>
> > +  - Jiri Kosina <jkosina@suse.cz>
> > +
> > +description: |+
> > +  HID over SPI provides support for various Human Interface Devices over the
> > +  SPI bus. These devices can be for example touchpads, keyboards, touch screens
> > +  or sensors.
> > +
> > +  The specification has been written by Microsoft and is currently available here:
> > +  https://www.microsoft.com/en-us/download/details.aspx?id=103325
> > +
> > +  If this binding is used, the kernel module spi-hid will handle the communication
> > +  with the device and the generic hid core layer will handle the protocol.
> > +
> > +allOf:
> > +  - $ref: /schemas/input/touchscreen/touchscreen.yaml#
> > +
> > +properties:
> > +  compatible:
> > +    oneOf:
> > +      - items:
> > +          - enum:
> > +              - microsoft,g6-touch-digitizer
> > +          - const: hid-over-spi
> > +      - description: Just "hid-over-spi" alone is allowed, but not recommended.
> > +        const: hid-over-spi
> > +
> > +  reg:
> > +    maxItems: 1
> > +
> > +  interrupts:
> > +    maxItems: 1
> > +
> > +  reset-gpios:
> > +    maxItems: 1
> > +    description:
> > +      GPIO specifier for the digitizer's reset pin (active low). The line must
> > +      be flagged with GPIO_ACTIVE_LOW.
> > +
> > +  vdd-supply:
> > +    description:
> > +      Regulator for the VDD supply voltage.
>
> Is this part of the spec? This won't scale for multiple devices with
> different power rails.

This is not part of the spec but is needed for power management. Is it okay I
mark it as optional? Thank you.

>
> > +
> > +  input-report-header-address:
> > +    $ref: /schemas/types.yaml#/definitions/uint32
> > +    minimum: 0
> > +    maximum: 0xffffff
> > +    description:
> > +      A value to be included in the Read Approval packet, listing an address of
> > +      the input report header to be put on the SPI bus. This address has 24
> > +      bits.
> > +
> > +  input-report-body-address:
> > +    $ref: /schemas/types.yaml#/definitions/uint32
> > +    minimum: 0
> > +    maximum: 0xffffff
> > +    description:
> > +     A value to be included in the Read Approval packet, listing an address of
> > +      the input report body to be put on the SPI bus. This address has 24 bits.
> > +
> > +  output-report-address:
> > +    $ref: /schemas/types.yaml#/definitions/uint32
> > +    minimum: 0
> > +    maximum: 0xffffff
> > +    description:
> > +      A value to be included in the Output Report sent by the host, listing an
> > +      address where the output report on the SPI bus is to be written to. This
> > +      address has 24 bits.
> > +
> > +  post-power-on-delay-ms:
> > +    description:
> > +      Optional time in ms required by the device after enabling its regulators
> > +      or powering it on, before it is ready for communication.
>
> Drop. This should be implied by the compatible.

Thank you, I will fix this in v2.

>
> > +
> > +  minimal-reset-delay-ms:
> > +    description:
> > +      Optional minimum amount of time in ms that device needs to be in reset
> > +      state for the reset to take effect.
>
> Drop. This should be implied by the compatible.

I will fix this in v2.

>
> > +
> > +  read-opcode:
> > +  $ref: /schemas/types.yaml#/definitions/uint8
> > +    description:
> > +      Value to be used in Read Approval packets. 1 byte.
> > +
> > +  write-opcode:
> > +  $ref: /schemas/types.yaml#/definitions/uint8
> > +    description:
> > +      Value to be used in Write Approval packets. 1 byte.
>
> Why are these and the address properties above not defined by the
> spec? Do they vary for a specific device? If not, then they should be
> implied by the compatible.

These properties are not defined by the spec:

"The Input Report Address (header or body) and READ opcode are retrieved
from ACPI."

Same for the output report address and write opcode. I will drop these in v2.

>
> > +
> > +  hid-over-spi-flags:
> > +  $ref: /schemas/types.yaml#/definitions/uint16
> > +    description:
> > +      16 bits.
> > +      Bits 0-12 - Reserved (must be 0)
> > +      Bit 13 - SPI Write Mode. Possible values -
> > +        * 0b0- Writes are carried out in Single-SPI mode
> > +        * 0b1- Writes are carried out in the Multi-SPI mode specified by bits
> > +               14-15
> > +      Bits 14-15 - Multi-SPI Mode. Possible values -
> > +        * 0b00- Single SPI
> > +        * 0b01- Dual SPI
> > +        * 0b10- Quad SPI
>
> We already have SPI properties to define the bus width for read and write.

Will fix this in v2.

>
> > +
> > +required:
> > +  - compatible
> > +  - interrupts
> > +  - reset-gpios
> > +  - vdd-supply
> > +  - input-report-header-address
> > +  - input-report-body-address
> > +  - output-report-address
> > +  - read-opcode
> > +  - write-opcode
> > +  - hid-over-spi-flags
> > +
> > +additionalProperties: false
> > +
> > +examples:
> > +  - |
> > +    #include <dt-bindings/interrupt-controller/irq.h>
> > +    #include <dt-bindings/gpio/gpio.h>
> > +
> > +    spi {
> > +      #address-cells = <1>;
> > +      #size-cells = <0>;
> > +
> > +      hid@0 {
> > +        compatible = "hid-over-spi";
> > +        reg = <0x0>;
> > +        interrupts-extended = <&gpio 42 IRQ_TYPE_EDGE_FALLING>;
> > +        reset-gpios = <&gpio 27 GPIO_ACTIVE_LOW>;
> > +        vdd-supply = <&pm8350c_l3>;
> > +        pinctrl-names = "default";
> > +        pinctrl-0 = <&ts_d6_reset_assert &ts_d6_int_bias>;
> > +        input-report-header-address = <0x1000>;
> > +        input-report-body-address = <0x1004>;
> > +        output-report-address = <0x2000>;
> > +        read-opcode = <0x0b>;
> > +        write-opcode = <0x02>;
> > +        hid-over-spi-flags = <0x0000>;
> > +        post-power-on-delay-ms = <5>;
> > +        minimal-reset-delay-ms = <5>;
> > +      };
> > +    };
> > \ No newline at end of file
>
> Fix this.

Will fix this in v2.

>
> Rob

Re: [PATCH 09/12] dt-bindings: input: Document hid-over-spi DT schema

[Jingyuan Liang]

On Fri, Mar 6, 2026 at 11:25 PM Val Packett <val@packett.cool> wrote:
>
>
> On 3/3/26 3:13 AM, Jingyuan Liang wrote:
> > Documentation describes the required and optional properties for
> > implementing Device Tree for a Microsoft G6 Touch Digitizer that
> > supports HID over SPI Protocol 1.0 specification.
> > […]
> > +properties:
> > +  compatible:
> > +    oneOf:
> > +      - items:
> > +          - enum:
> > +              - microsoft,g6-touch-digitizer
> > +          - const: hid-over-spi
> > +      - description: Just "hid-over-spi" alone is allowed, but not recommended.
> > […]
> > +required:
> > +  - compatible
> > +  - interrupts
> > +  - reset-gpios
>
> Why is reset required? Is it so implausible on some device implementing
> the spec there wouldn't be a reset gpio?
>
> > +  - vdd-supply
> Linux makes up a dummy regulator if DT doesn't provide one, so can
> regulators even be required?
> > […]
> > +        compatible = "hid-over-spi";
> Not following your own recommendation from above :)

Thanks! I will fix this in v2.

> > +        reg = <0x0>;
> > +        interrupts-extended = <&gpio 42 IRQ_TYPE_EDGE_FALLING>;
> > +        reset-gpios = <&gpio 27 GPIO_ACTIVE_LOW>;
> > +        vdd-supply = <&pm8350c_l3>;
> > +        pinctrl-names = "default";
> > +        pinctrl-0 = <&ts_d6_reset_assert &ts_d6_int_bias>;
>
> Heh, "reset_assert" is a name implying it would actually set the value
> from the pinctrl properties, which is what had to be done before
> reset-gpios were supported. But now reset-gpios are supported.

Taken from the original patch. Will fix this in v2.

>
>
> Thanks,
> ~val
>
>
> P.S. happy to see work on this happen again!
>

Re: [PATCH 09/12] dt-bindings: input: Document hid-over-spi DT schema

[Jingyuan Liang]

On Wed, Mar 11, 2026 at 5:58 PM Jingyuan Liang <jingyliang@chromium.org> wrote:
>
> (Resending to the list. Apologies, I accidentally dropped the CCs on
> my initial reply!)
>
> On Tue, Mar 3, 2026 at 5:53 AM Rob Herring <robh@kernel.org> wrote:
> >
> > On Tue, Mar 3, 2026 at 12:14 AM Jingyuan Liang <jingyliang@chromium.org> wrote:
> > >
> > > Documentation describes the required and optional properties for
> > > implementing Device Tree for a Microsoft G6 Touch Digitizer that
> > > supports HID over SPI Protocol 1.0 specification.
> > >
> > > The properties are common to HID over SPI.
> > >
> > > Signed-off-by: Dmitry Antipov <dmanti@microsoft.com>
> > > Signed-off-by: Jarrett Schultz <jaschultz@microsoft.com>
> > > Signed-off-by: Jingyuan Liang <jingyliang@chromium.org>
> > > ---
> > >  .../devicetree/bindings/input/hid-over-spi.yaml    | 153 +++++++++++++++++++++
> > >  1 file changed, 153 insertions(+)
> > >
> > > diff --git a/Documentation/devicetree/bindings/input/hid-over-spi.yaml b/Documentation/devicetree/bindings/input/hid-over-spi.yaml
> > > new file mode 100644
> > > index 000000000000..b623629ed9d3
> > > --- /dev/null
> > > +++ b/Documentation/devicetree/bindings/input/hid-over-spi.yaml
> > > @@ -0,0 +1,153 @@
> > > +# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
> > > +%YAML 1.2
> > > +---
> > > +$id: http://devicetree.org/schemas/input/hid-over-spi.yaml#
> > > +$schema: http://devicetree.org/meta-schemas/core.yaml#
> > > +
> > > +title: HID over SPI Devices
> > > +
> > > +maintainers:
> > > +  - Benjamin Tissoires <benjamin.tissoires@redhat.com>
> > > +  - Jiri Kosina <jkosina@suse.cz>
> > > +
> > > +description: |+
> > > +  HID over SPI provides support for various Human Interface Devices over the
> > > +  SPI bus. These devices can be for example touchpads, keyboards, touch screens
> > > +  or sensors.
> > > +
> > > +  The specification has been written by Microsoft and is currently available here:
> > > +  https://www.microsoft.com/en-us/download/details.aspx?id=103325
> > > +
> > > +  If this binding is used, the kernel module spi-hid will handle the communication
> > > +  with the device and the generic hid core layer will handle the protocol.
> > > +
> > > +allOf:
> > > +  - $ref: /schemas/input/touchscreen/touchscreen.yaml#
> > > +
> > > +properties:
> > > +  compatible:
> > > +    oneOf:
> > > +      - items:
> > > +          - enum:
> > > +              - microsoft,g6-touch-digitizer
> > > +          - const: hid-over-spi
> > > +      - description: Just "hid-over-spi" alone is allowed, but not recommended.
> > > +        const: hid-over-spi
> > > +
> > > +  reg:
> > > +    maxItems: 1
> > > +
> > > +  interrupts:
> > > +    maxItems: 1
> > > +
> > > +  reset-gpios:
> > > +    maxItems: 1
> > > +    description:
> > > +      GPIO specifier for the digitizer's reset pin (active low). The line must
> > > +      be flagged with GPIO_ACTIVE_LOW.
> > > +
> > > +  vdd-supply:
> > > +    description:
> > > +      Regulator for the VDD supply voltage.
> >
> > Is this part of the spec? This won't scale for multiple devices with
> > different power rails.
>
> This is not part of the spec but is needed for power management. Is it okay I
> mark it as optional? Thank you.
>
> >
> > > +
> > > +  input-report-header-address:
> > > +    $ref: /schemas/types.yaml#/definitions/uint32
> > > +    minimum: 0
> > > +    maximum: 0xffffff
> > > +    description:
> > > +      A value to be included in the Read Approval packet, listing an address of
> > > +      the input report header to be put on the SPI bus. This address has 24
> > > +      bits.
> > > +
> > > +  input-report-body-address:
> > > +    $ref: /schemas/types.yaml#/definitions/uint32
> > > +    minimum: 0
> > > +    maximum: 0xffffff
> > > +    description:
> > > +     A value to be included in the Read Approval packet, listing an address of
> > > +      the input report body to be put on the SPI bus. This address has 24 bits.
> > > +
> > > +  output-report-address:
> > > +    $ref: /schemas/types.yaml#/definitions/uint32
> > > +    minimum: 0
> > > +    maximum: 0xffffff
> > > +    description:
> > > +      A value to be included in the Output Report sent by the host, listing an
> > > +      address where the output report on the SPI bus is to be written to. This
> > > +      address has 24 bits.
> > > +
> > > +  post-power-on-delay-ms:
> > > +    description:
> > > +      Optional time in ms required by the device after enabling its regulators
> > > +      or powering it on, before it is ready for communication.
> >
> > Drop. This should be implied by the compatible.
>
> Thank you, I will fix this in v2.
>
> >
> > > +
> > > +  minimal-reset-delay-ms:
> > > +    description:
> > > +      Optional minimum amount of time in ms that device needs to be in reset
> > > +      state for the reset to take effect.
> >
> > Drop. This should be implied by the compatible.
>
> I will fix this in v2.
>
> >
> > > +
> > > +  read-opcode:
> > > +  $ref: /schemas/types.yaml#/definitions/uint8
> > > +    description:
> > > +      Value to be used in Read Approval packets. 1 byte.
> > > +
> > > +  write-opcode:
> > > +  $ref: /schemas/types.yaml#/definitions/uint8
> > > +    description:
> > > +      Value to be used in Write Approval packets. 1 byte.
> >
> > Why are these and the address properties above not defined by the
> > spec? Do they vary for a specific device? If not, then they should be
> > implied by the compatible.
>
> These properties are not defined by the spec:
>
> "The Input Report Address (header or body) and READ opcode are retrieved
> from ACPI."
>
> Same for the output report address and write opcode. I will drop these in v2.

Hi Rob,

Please disregard my previous reply about dropping the read/write opcodes and
input/output addresses. The spec does not define these fields. Instead, it says
these values are retrieved from ACPI _DSM methods. If we remove them from
the binding, the driver is not very generic. Would it be okay to keep them?

>
> >
> > > +
> > > +  hid-over-spi-flags:
> > > +  $ref: /schemas/types.yaml#/definitions/uint16
> > > +    description:
> > > +      16 bits.
> > > +      Bits 0-12 - Reserved (must be 0)
> > > +      Bit 13 - SPI Write Mode. Possible values -
> > > +        * 0b0- Writes are carried out in Single-SPI mode
> > > +        * 0b1- Writes are carried out in the Multi-SPI mode specified by bits
> > > +               14-15
> > > +      Bits 14-15 - Multi-SPI Mode. Possible values -
> > > +        * 0b00- Single SPI
> > > +        * 0b01- Dual SPI
> > > +        * 0b10- Quad SPI
> >
> > We already have SPI properties to define the bus width for read and write.
>
> Will fix this in v2.
>
> >
> > > +
> > > +required:
> > > +  - compatible
> > > +  - interrupts
> > > +  - reset-gpios
> > > +  - vdd-supply
> > > +  - input-report-header-address
> > > +  - input-report-body-address
> > > +  - output-report-address
> > > +  - read-opcode
> > > +  - write-opcode
> > > +  - hid-over-spi-flags
> > > +
> > > +additionalProperties: false
> > > +
> > > +examples:
> > > +  - |
> > > +    #include <dt-bindings/interrupt-controller/irq.h>
> > > +    #include <dt-bindings/gpio/gpio.h>
> > > +
> > > +    spi {
> > > +      #address-cells = <1>;
> > > +      #size-cells = <0>;
> > > +
> > > +      hid@0 {
> > > +        compatible = "hid-over-spi";
> > > +        reg = <0x0>;
> > > +        interrupts-extended = <&gpio 42 IRQ_TYPE_EDGE_FALLING>;
> > > +        reset-gpios = <&gpio 27 GPIO_ACTIVE_LOW>;
> > > +        vdd-supply = <&pm8350c_l3>;
> > > +        pinctrl-names = "default";
> > > +        pinctrl-0 = <&ts_d6_reset_assert &ts_d6_int_bias>;
> > > +        input-report-header-address = <0x1000>;
> > > +        input-report-body-address = <0x1004>;
> > > +        output-report-address = <0x2000>;
> > > +        read-opcode = <0x0b>;
> > > +        write-opcode = <0x02>;
> > > +        hid-over-spi-flags = <0x0000>;
> > > +        post-power-on-delay-ms = <5>;
> > > +        minimal-reset-delay-ms = <5>;
> > > +      };
> > > +    };
> > > \ No newline at end of file
> >
> > Fix this.
>
> Will fix this in v2.
>
> >
> > Rob

Re: [PATCH 07/12] HID: spi_hid: add ACPI support for SPI over HID

[Jingyuan Liang]

On Tue, Mar 10, 2026 at 10:27 PM Dmitry Torokhov
<dmitry.torokhov@gmail.com> wrote:
>
> On Tue, Mar 03, 2026 at 06:12:59AM +0000, Jingyuan Liang wrote:
> > From: Angela Czubak <acz@semihalf.com>
> >
> > Detect SPI HID devices described in ACPI.
> >
> > Signed-off-by: Angela Czubak <acz@semihalf.com>
> > Signed-off-by: Jingyuan Liang <jingyliang@chromium.org>
> > ---
> >  drivers/hid/spi-hid/Kconfig        |  15 +++
> >  drivers/hid/spi-hid/Makefile       |   1 +
> >  drivers/hid/spi-hid/spi-hid-acpi.c | 253 +++++++++++++++++++++++++++++++++++++
> >  drivers/hid/spi-hid/spi-hid-core.c |  27 +---
> >  drivers/hid/spi-hid/spi-hid.h      |  44 +++++++
> >  5 files changed, 316 insertions(+), 24 deletions(-)
> >
> > diff --git a/drivers/hid/spi-hid/Kconfig b/drivers/hid/spi-hid/Kconfig
> > index 836fdefe8345..114b1e00da39 100644
> > --- a/drivers/hid/spi-hid/Kconfig
> > +++ b/drivers/hid/spi-hid/Kconfig
> > @@ -10,6 +10,21 @@ menuconfig SPI_HID
> >
> >  if SPI_HID
> >
> > +config SPI_HID_ACPI
> > +     tristate "HID over SPI transport layer ACPI driver"
> > +     depends on ACPI
> > +     select SPI_HID_CORE
> > +     help
> > +       Say Y here if you use a keyboard, a touchpad, a touchscreen, or any
> > +       other HID based devices which are connected to your computer via SPI.
> > +       This driver supports ACPI-based systems.
> > +
> > +       If unsure, say N.
> > +
> > +       This support is also available as a module.  If so, the module
> > +       will be called spi-hid-acpi. It will also build/depend on the
> > +       module spi-hid.
> > +
> >  config SPI_HID_CORE
> >       tristate
> >  endif
> > diff --git a/drivers/hid/spi-hid/Makefile b/drivers/hid/spi-hid/Makefile
> > index 92e24cddbfc2..753c7b7a7844 100644
> > --- a/drivers/hid/spi-hid/Makefile
> > +++ b/drivers/hid/spi-hid/Makefile
> > @@ -7,3 +7,4 @@
> >
> >  obj-$(CONFIG_SPI_HID_CORE)   += spi-hid.o
> >  spi-hid-objs                         = spi-hid-core.o
> > +obj-$(CONFIG_SPI_HID_ACPI)   += spi-hid-acpi.o
> > diff --git a/drivers/hid/spi-hid/spi-hid-acpi.c b/drivers/hid/spi-hid/spi-hid-acpi.c
> > new file mode 100644
> > index 000000000000..612e74fe72f9
> > --- /dev/null
> > +++ b/drivers/hid/spi-hid/spi-hid-acpi.c
> > @@ -0,0 +1,253 @@
> > +// SPDX-License-Identifier: GPL-2.0
> > +/*
> > + * HID over SPI protocol, ACPI related code
> > + *
> > + * Copyright (c) 2021 Microsoft Corporation
> > + * Copyright (c) 2026 Google LLC
> > + *
> > + * This code was forked out of the HID over SPI core code, which is partially
> > + * based on "HID over I2C protocol implementation:
> > + *
> > + * Copyright (c) 2012 Benjamin Tissoires <benjamin.tissoires@gmail.com>
> > + * Copyright (c) 2012 Ecole Nationale de l'Aviation Civile, France
> > + * Copyright (c) 2012 Red Hat, Inc
> > + *
> > + * which in turn is partially based on "USB HID support for Linux":
> > + *
> > + * Copyright (c) 1999 Andreas Gal
> > + * Copyright (c) 2000-2005 Vojtech Pavlik <vojtech@suse.cz>
> > + * Copyright (c) 2005 Michael Haboustak <mike-@cinci.rr.com> for Concept2, Inc
> > + * Copyright (c) 2007-2008 Oliver Neukum
> > + * Copyright (c) 2006-2010 Jiri Kosina
> > + */
> > +
> > +#include <linux/acpi.h>
> > +#include <linux/delay.h>
> > +#include <linux/device.h>
> > +#include <linux/kernel.h>
> > +#include <linux/module.h>
> > +#include <linux/reset.h>
> > +#include <linux/uuid.h>
> > +
> > +#include "spi-hid.h"
> > +
> > +/* Config structure is filled with data from ACPI */
> > +struct spi_hid_acpi_config {
> > +     struct spihid_ops ops;
> > +
> > +     struct spi_hid_conf property_conf;
> > +     u32 post_power_on_delay_ms;
> > +     u32 minimal_reset_delay_ms;
> > +     struct acpi_device *adev;
> > +};
> > +
> > +/* HID SPI Device: 6e2ac436-0fcf41af-a265-b32a220dcfab */
> > +static guid_t spi_hid_guid =
> > +     GUID_INIT(0x6E2AC436, 0x0FCF, 0x41AF,
> > +               0xA2, 0x65, 0xB3, 0x2A, 0x22, 0x0D, 0xCF, 0xAB);
> > +
> > +static int spi_hid_acpi_populate_config(struct spi_hid_acpi_config *conf,
> > +                                     struct acpi_device *adev)
> > +{
> > +     acpi_handle handle = acpi_device_handle(adev);
> > +     union acpi_object *obj;
> > +
> > +     conf->adev = adev;
> > +
> > +     /* Revision 3 for HID over SPI V1, see specification. */
> > +     obj = acpi_evaluate_dsm_typed(handle, &spi_hid_guid, 3, 1, NULL,
> > +                                   ACPI_TYPE_INTEGER);
> > +     if (!obj) {
> > +             acpi_handle_err(handle,
> > +                             "Error _DSM call to get HID input report header address failed");
> > +             return -ENODEV;
> > +     }
> > +     conf->property_conf.input_report_header_address = obj->integer.value;
> > +     ACPI_FREE(obj);
> > +
> > +     obj = acpi_evaluate_dsm_typed(handle, &spi_hid_guid, 3, 2, NULL,
> > +                                   ACPI_TYPE_INTEGER);
> > +     if (!obj) {
> > +             acpi_handle_err(handle,
> > +                             "Error _DSM call to get HID input report body address failed");
> > +             return -ENODEV;
> > +     }
> > +     conf->property_conf.input_report_body_address = obj->integer.value;
> > +     ACPI_FREE(obj);
> > +
> > +     obj = acpi_evaluate_dsm_typed(handle, &spi_hid_guid, 3, 3, NULL,
> > +                                   ACPI_TYPE_INTEGER);
> > +     if (!obj) {
> > +             acpi_handle_err(handle,
> > +                             "Error _DSM call to get HID output report header address failed");
> > +             return -ENODEV;
> > +     }
> > +     conf->property_conf.output_report_address = obj->integer.value;
> > +     ACPI_FREE(obj);
> > +
> > +     obj = acpi_evaluate_dsm_typed(handle, &spi_hid_guid, 3, 4, NULL,
> > +                                   ACPI_TYPE_BUFFER);
> > +     if (!obj) {
> > +             acpi_handle_err(handle,
> > +                             "Error _DSM call to get HID read opcode failed");
> > +             return -ENODEV;
> > +     }
> > +     if (obj->buffer.length == 1) {
> > +             conf->property_conf.read_opcode = obj->buffer.pointer[0];
> > +     } else {
> > +             acpi_handle_err(handle,
> > +                             "Error _DSM call to get HID read opcode, too long buffer");
> > +             ACPI_FREE(obj);
> > +             return -ENODEV;
> > +     }
> > +     ACPI_FREE(obj);
> > +
> > +     obj = acpi_evaluate_dsm_typed(handle, &spi_hid_guid, 3, 5, NULL,
> > +                                   ACPI_TYPE_BUFFER);
> > +     if (!obj) {
> > +             acpi_handle_err(handle,
> > +                             "Error _DSM call to get HID write opcode failed");
> > +             return -ENODEV;
> > +     }
> > +     if (obj->buffer.length == 1) {
> > +             conf->property_conf.write_opcode = obj->buffer.pointer[0];
> > +     } else {
> > +             acpi_handle_err(handle,
> > +                             "Error _DSM call to get HID write opcode, too long buffer");
> > +             ACPI_FREE(obj);
> > +             return -ENODEV;
> > +     }
> > +     ACPI_FREE(obj);
> > +
> > +     /* Value not provided in ACPI,*/
> > +     conf->post_power_on_delay_ms = 5;
> > +     conf->minimal_reset_delay_ms = 150;
> > +
> > +     if (!acpi_has_method(handle, "_RST")) {
> > +             acpi_handle_err(handle, "No reset method for acpi handle");
> > +             return -ENODEV;
>
> I would return -EINVAL as we have the device with right _DSM but without
> mandated by the spec _RST.

Thanks! Will fix this in v2.

>
> > +     }
> > +
> > +     /* FIXME: not reading hid-over-spi-flags, multi-SPI not supported */
> > +
> > +     return 0;
> > +}
> > +
> > +static int spi_hid_acpi_power_none(struct spihid_ops *ops)
> > +{
> > +     return 0;
> > +}
> > +
> > +static int spi_hid_acpi_power_down(struct spihid_ops *ops)
> > +{
> > +     struct spi_hid_acpi_config *conf = container_of(ops,
> > +                                                     struct spi_hid_acpi_config,
> > +                                                     ops);
> > +
> > +     return acpi_device_set_power(conf->adev, ACPI_STATE_D3);
> > +}
> > +
> > +static int spi_hid_acpi_power_up(struct spihid_ops *ops)
> > +{
> > +     struct spi_hid_acpi_config *conf = container_of(ops,
> > +                                                     struct spi_hid_acpi_config,
> > +                                                     ops);
> > +     int error;
> > +
> > +     error = acpi_device_set_power(conf->adev, ACPI_STATE_D0);
> > +     if (error) {
> > +             dev_err(&conf->adev->dev, "Error could not power up ACPI device: %d.", error);
> > +             return error;
> > +     }
> > +
> > +     if (conf->post_power_on_delay_ms)
> > +             msleep(conf->post_power_on_delay_ms);
> > +
> > +     return 0;
> > +}
> > +
> > +static int spi_hid_acpi_assert_reset(struct spihid_ops *ops)
> > +{
> > +     return 0;
> > +}
> > +
> > +static int spi_hid_acpi_deassert_reset(struct spihid_ops *ops)
> > +{
> > +     struct spi_hid_acpi_config *conf = container_of(ops,
> > +                                                     struct spi_hid_acpi_config,
> > +                                                     ops);
> > +
> > +     return device_reset(&conf->adev->dev);
> > +}
> > +
> > +static void spi_hid_acpi_sleep_minimal_reset_delay(struct spihid_ops *ops)
> > +{
> > +     struct spi_hid_acpi_config *conf = container_of(ops,
> > +                                                     struct spi_hid_acpi_config,
> > +                                                     ops);
> > +     usleep_range(1000 * conf->minimal_reset_delay_ms,
> > +                  1000 * (conf->minimal_reset_delay_ms + 1));
>
> I'd probably use "fsleep(conf->minimal_reset_delay_ms * 1000)".

I will fix this in v2. And do the same for the of driver.

>
> > +}
> > +
> > +static int spi_hid_acpi_probe(struct spi_device *spi)
> > +{
> > +     struct device *dev = &spi->dev;
> > +     struct acpi_device *adev;
> > +     struct spi_hid_acpi_config *config;
> > +     int error;
> > +
> > +     adev = ACPI_COMPANION(dev);
> > +     if (!adev) {
> > +             dev_err(dev, "Error could not get ACPI device.");
> > +             return -ENODEV;
> > +     }
> > +
> > +     config = devm_kzalloc(dev, sizeof(struct spi_hid_acpi_config),
> > +                           GFP_KERNEL);
> > +     if (!config)
> > +             return -ENOMEM;
> > +
> > +     if (acpi_device_power_manageable(adev)) {
> > +             config->ops.power_up = spi_hid_acpi_power_up;
> > +             config->ops.power_down = spi_hid_acpi_power_down;
> > +     } else {
> > +             config->ops.power_up = spi_hid_acpi_power_none;
> > +             config->ops.power_down = spi_hid_acpi_power_none;
> > +     }
> > +     config->ops.assert_reset = spi_hid_acpi_assert_reset;
> > +     config->ops.deassert_reset = spi_hid_acpi_deassert_reset;
> > +     config->ops.sleep_minimal_reset_delay =
> > +             spi_hid_acpi_sleep_minimal_reset_delay;
> > +
> > +     error = spi_hid_acpi_populate_config(config, adev);
> > +     if (error) {
> > +             dev_err(dev, "%s: unable to populate config data.", __func__);
> > +             return error;
> > +     }
>
> I would add a blank line.

Sure! Will fix this in v2.

>
> > +     return spi_hid_core_probe(spi, &config->ops, &config->property_conf);
> > +}
> > +
> > +static const struct acpi_device_id spi_hid_acpi_match[] = {
> > +     { "ACPI0C51", 0 },
> > +     { "PNP0C51", 0 },
> > +     { },
>
> No comma on sentinels.

Will fix this in v2.

>
> > +};
> > +MODULE_DEVICE_TABLE(acpi, spi_hid_acpi_match);
> > +
> > +static struct spi_driver spi_hid_acpi_driver = {
> > +     .driver = {
> > +             .name   = "spi_hid_acpi",
> > +             .owner  = THIS_MODULE,
> > +             .acpi_match_table = ACPI_PTR(spi_hid_acpi_match),
>
> This is dependent on ACPI, so no need to sue ACPI_PTR().

Will fix this in v2 and remove of_match_ptr in the of driver as well.

>
> > +             .probe_type = PROBE_PREFER_ASYNCHRONOUS,
> > +             .dev_groups = spi_hid_groups,
> > +     },
> > +     .probe          = spi_hid_acpi_probe,
> > +     .remove         = spi_hid_core_remove,
> > +};
> > +
> > +module_spi_driver(spi_hid_acpi_driver);
> > +
> > +MODULE_DESCRIPTION("HID over SPI ACPI transport driver");
> > +MODULE_AUTHOR("Angela Czubak <aczubak@google.com>");
> > +MODULE_LICENSE("GPL");
> > diff --git a/drivers/hid/spi-hid/spi-hid-core.c b/drivers/hid/spi-hid/spi-hid-core.c
> > index e3273846267e..02beb209a92d 100644
> > --- a/drivers/hid/spi-hid/spi-hid-core.c
> > +++ b/drivers/hid/spi-hid/spi-hid-core.c
> > @@ -43,6 +43,9 @@
> >  #include <linux/wait.h>
> >  #include <linux/workqueue.h>
> >
> > +#include "spi-hid.h"
> > +#include "spi-hid-core.h"
> > +
> >  /* Protocol constants */
> >  #define SPI_HID_READ_APPROVAL_CONSTANT               0xff
> >  #define SPI_HID_INPUT_HEADER_SYNC_BYTE               0x5a
> > @@ -105,30 +108,6 @@ struct spi_hid_output_report {
> >       u8 *content;
> >  };
> >
> > -/* struct spi_hid_conf - Conf provided to the core */
> > -struct spi_hid_conf {
> > -     u32 input_report_header_address;
> > -     u32 input_report_body_address;
> > -     u32 output_report_address;
> > -     u8 read_opcode;
> > -     u8 write_opcode;
> > -};
> > -
> > -/**
> > - * struct spihid_ops - Ops provided to the core
> > - * @power_up: do sequencing to power up the device
> > - * @power_down: do sequencing to power down the device
> > - * @assert_reset: do sequencing to assert the reset line
> > - * @deassert_reset: do sequencing to deassert the reset line
> > - */
> > -struct spihid_ops {
> > -     int (*power_up)(struct spihid_ops *ops);
> > -     int (*power_down)(struct spihid_ops *ops);
> > -     int (*assert_reset)(struct spihid_ops *ops);
> > -     int (*deassert_reset)(struct spihid_ops *ops);
> > -     void (*sleep_minimal_reset_delay)(struct spihid_ops *ops);
> > -};
> > -
> >  static struct hid_ll_driver spi_hid_ll_driver;
> >
> >  static void spi_hid_populate_read_approvals(const struct spi_hid_conf *conf,
> > diff --git a/drivers/hid/spi-hid/spi-hid.h b/drivers/hid/spi-hid/spi-hid.h
> > new file mode 100644
> > index 000000000000..1fdd45262647
> > --- /dev/null
> > +++ b/drivers/hid/spi-hid/spi-hid.h
> > @@ -0,0 +1,44 @@
> > +/* SPDX-License-Identifier: GPL-2.0 */
> > +/*
> > + * Copyright (c) 2021 Microsoft Corporation
> > + * Copyright (c) 2026 Google LLC
> > + */
> > +
> > +#ifndef SPI_HID_H
> > +#define SPI_HID_H
> > +
> > +#include <linux/spi/spi.h>
> > +#include <linux/sysfs.h>
> > +
> > +/* struct spi_hid_conf - Conf provided to the core */
> > +struct spi_hid_conf {
> > +     u32 input_report_header_address;
> > +     u32 input_report_body_address;
> > +     u32 output_report_address;
> > +     u8 read_opcode;
> > +     u8 write_opcode;
> > +};
> > +
> > +/**
> > + * struct spihid_ops - Ops provided to the core
> > + * @power_up: do sequencing to power up the device
> > + * @power_down: do sequencing to power down the device
> > + * @assert_reset: do sequencing to assert the reset line
> > + * @deassert_reset: do sequencing to deassert the reset line
> > + */
> > +struct spihid_ops {
> > +     int (*power_up)(struct spihid_ops *ops);
> > +     int (*power_down)(struct spihid_ops *ops);
> > +     int (*assert_reset)(struct spihid_ops *ops);
> > +     int (*deassert_reset)(struct spihid_ops *ops);
> > +     void (*sleep_minimal_reset_delay)(struct spihid_ops *ops);
> > +};
> > +
> > +int spi_hid_core_probe(struct spi_device *spi, struct spihid_ops *ops,
> > +                    struct spi_hid_conf *conf);
> > +
> > +void spi_hid_core_remove(struct spi_device *spi);
> > +
> > +extern const struct attribute_group *spi_hid_groups[];
> > +
> > +#endif /* SPI_HID_H */
>
> I am not sure if this belongs to this patch or if it should be better in
> the patch introducing the main driver from the beginning.

These definitions were in spi-hid-core.c in the previous patch introducing
the main driver because it was only used in one .c file. This patch introduces
spi-hid-acpi.c and now two .c files need it so I created a separate .h
file here.

>
> For the ACPI part:
>
> Reviewed-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>
>
> Thanks.
>
> --
> Dmitry