[PATCH v5 10/11] HID: spi-hid: add power management implementation

[Jingyuan Liang <jingyliang@chromium.org>]

Implement HID over SPI driver power management callbacks.

Tested-by: Dale Whinham <daleyo@gmail.com>
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 | 185 +++++++++++++++++++++++++++++++++++++
 drivers/hid/spi-hid/spi-hid-core.h |   2 +
 drivers/hid/spi-hid/spi-hid-of.c   |   1 +
 drivers/hid/spi-hid/spi-hid.h      |   1 +
 5 files changed, 190 insertions(+)

diff --git a/drivers/hid/spi-hid/spi-hid-acpi.c b/drivers/hid/spi-hid/spi-hid-acpi.c
index 31ca3fa336cd..a52cafe86c05 100644
--- a/drivers/hid/spi-hid/spi-hid-acpi.c
+++ b/drivers/hid/spi-hid/spi-hid-acpi.c
@@ -246,6 +246,7 @@ static struct spi_driver spi_hid_acpi_driver = {
 	.driver = {
 		.name	= "spi_hid_acpi",
 		.owner	= THIS_MODULE,
+		.pm	= &spi_hid_core_pm,
 		.acpi_match_table = 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 f4e9b4e1294e..66bfc251bd91 100644
--- a/drivers/hid/spi-hid/spi-hid-core.c
+++ b/drivers/hid/spi-hid/spi-hid-core.c
@@ -36,6 +36,8 @@
 #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>
@@ -60,6 +62,7 @@
 
 #define SPI_HID_MAX_RESET_ATTEMPTS	3
 #define SPI_HID_RESP_TIMEOUT		1000
+#define SPI_HID_RESET_TIMEOUT		1000
 
 /* Protocol message size constants */
 #define SPI_HID_READ_APPROVAL_LEN		5
@@ -91,6 +94,11 @@
  * ll_close. Input reports are only forwarded while this flag is set.
  */
 #define SPI_HID_STARTED	6
+/*
+ * dead indicates that the device was powered off after too many failed
+ * resets. It stays off until the driver is rebound, even across resume.
+ */
+#define SPI_HID_DEAD	7
 
 /* Processed data from input report header */
 struct spi_hid_input_header {
@@ -242,6 +250,148 @@ static const char *spi_hid_power_mode_string(enum hidspi_power_state power_state
 	}
 }
 
+/*
+ * Wait for the device descriptor response after reset; the device then takes
+ * requests. Set READY here: the report descriptor check that normally sets it
+ * needs power_lock, which callers hold.
+ */
+static void spi_hid_wait_for_reset(struct spi_hid *shid)
+{
+	unsigned long timeout = msecs_to_jiffies(SPI_HID_RESET_TIMEOUT +
+						 SPI_HID_RESP_TIMEOUT);
+
+	if (!wait_for_completion_timeout(&shid->reset_done, timeout)) {
+		dev_warn(&shid->spi->dev,
+			 "Device descriptor not received after reset\n");
+		return;
+	}
+
+	set_bit(SPI_HID_READY, &shid->flags);
+}
+
+static int spi_hid_suspend(struct spi_hid *shid)
+{
+	int error;
+	struct device *dev = &shid->spi->dev;
+
+	/* HID driver suspend may talk to the device; responses need the IRQ. */
+	scoped_guard(mutex, &shid->power_lock) {
+		if (shid->power_state != HIDSPI_OFF && shid->hid) {
+			error = hid_driver_suspend(shid->hid, PMSG_SUSPEND);
+			if (error) {
+				dev_err(dev, "%s failed to suspend hid driver: %d\n",
+					__func__, error);
+				return error;
+			}
+		}
+	}
+
+	/*
+	 * disable_irq() waits for a running IRQ thread, so no new reset_work
+	 * can be queued after it returns. Then wait for any queued or running
+	 * instance. Must not hold power_lock here: reset_work takes it.
+	 */
+	disable_irq(shid->spi->irq);
+	cancel_work_sync(&shid->reset_work);
+
+	guard(mutex)(&shid->power_lock);
+	if (!device_may_wakeup(dev)) {
+		if (shid->power_state != HIDSPI_OFF) {
+			/* Device is fully reset on resume; drop stale state. */
+			clear_bit(SPI_HID_READY, &shid->flags);
+			clear_bit(SPI_HID_RESET_RESPONSE, &shid->flags);
+			clear_bit(SPI_HID_CREATE_DEVICE, &shid->flags);
+			clear_bit(SPI_HID_ERROR, &shid->flags);
+			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\n", __func__);
+				shid->regulator_error_count++;
+				shid->regulator_last_error = error;
+				/*
+				 * Undo partial suspend before returning error.
+				 * Complete the reset; RESET_PENDING stays set
+				 * until the device sends its reset response.
+				 */
+				shid->ops->sleep_minimal_reset_delay(shid->ops);
+				reinit_completion(&shid->reset_done);
+				shid->ops->deassert_reset(shid->ops);
+				enable_irq(shid->spi->irq);
+				if (shid->hid) {
+					spi_hid_wait_for_reset(shid);
+					hid_driver_reset_resume(shid->hid);
+				}
+				return error;
+			}
+
+			shid->power_state = HIDSPI_OFF;
+		}
+	}
+	return 0;
+}
+
+static int spi_hid_resume(struct spi_hid *shid)
+{
+	int error;
+	struct device *dev = &shid->spi->dev;
+	bool was_reset = false;
+
+	guard(mutex)(&shid->power_lock);
+	if (test_bit(SPI_HID_DEAD, &shid->flags)) {
+		/* Stay off; only balance disable_irq() in suspend. */
+		enable_irq(shid->spi->irq);
+		return 0;
+	}
+
+	if (!device_may_wakeup(dev)) {
+		if (shid->power_state == HIDSPI_OFF) {
+			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\n", __func__);
+				shid->regulator_error_count++;
+				shid->regulator_last_error = error;
+				/* Suspend runs next even if resume fails. */
+				enable_irq(shid->spi->irq);
+				return error;
+			}
+			shid->power_state = HIDSPI_ON;
+			reinit_completion(&shid->reset_done);
+			shid->ops->deassert_reset(shid->ops);
+			was_reset = true;
+		}
+	}
+
+	enable_irq(shid->spi->irq);
+
+	/*
+	 * For devices that may wake up, process work that was pending when
+	 * suspend cancelled reset_work. Otherwise suspend already dropped it.
+	 */
+	if (test_bit(SPI_HID_RESET_RESPONSE, &shid->flags) ||
+	    test_bit(SPI_HID_CREATE_DEVICE, &shid->flags) ||
+	    test_bit(SPI_HID_ERROR, &shid->flags))
+		schedule_work(&shid->reset_work);
+
+	if (shid->hid) {
+		if (was_reset)
+			spi_hid_wait_for_reset(shid);
+		error = hid_driver_reset_resume(shid->hid);
+		if (error) {
+			dev_err(dev, "%s: failed to reset resume hid driver: %d\n",
+				__func__, error);
+			return error;
+		}
+	}
+	return 0;
+}
+
 static void spi_hid_stop_hid(struct spi_hid *shid)
 {
 	struct hid_device *hid;
@@ -280,6 +430,7 @@ static void spi_hid_error_handler(struct spi_hid *shid)
 			shid->regulator_last_error = error;
 		}
 		shid->power_state = HIDSPI_OFF;
+		set_bit(SPI_HID_DEAD, &shid->flags);
 		/* Dead device: leave the IRQ permanently disabled. */
 		return;
 	}
@@ -561,6 +712,8 @@ static int spi_hid_dev_desc_response(struct spi_hid *shid,
 	shid->reset_attempts = 0;
 	set_bit(SPI_HID_CREATE_DEVICE, &shid->flags);
 	schedule_work(&shid->reset_work);
+	/* The device can take requests now; see spi_hid_wait_for_reset(). */
+	complete(&shid->reset_done);
 
 	return 0;
 }
@@ -1378,6 +1531,7 @@ int spi_hid_core_probe(struct spi_device *spi, struct spihid_ops *ops,
 	mutex_init(&shid->power_lock);
 	mutex_init(&shid->io_lock);
 	init_completion(&shid->output_done);
+	init_completion(&shid->reset_done);
 
 	INIT_WORK(&shid->reset_work, spi_hid_reset_work);
 
@@ -1411,6 +1565,18 @@ int spi_hid_core_probe(struct spi_device *spi, struct spihid_ops *ops,
 		return error;
 	}
 
+	/*
+	 * Use device_can_wakeup(), not device_may_wakeup(): power/wakeup can
+	 * change after probe, and the PM core checks it at suspend time.
+	 */
+	if (device_can_wakeup(dev)) {
+		error = devm_pm_set_wake_irq(dev, spi->irq);
+		if (error) {
+			dev_err(dev, "%s: failed to set wake IRQ\n", __func__);
+			return error;
+		}
+	}
+
 	error = shid->ops->power_up(shid->ops);
 	if (error) {
 		dev_err(dev, "%s: could not power up\n", __func__);
@@ -1451,6 +1617,25 @@ 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);
+
+	return spi_hid_suspend(shid);
+}
+
+static int spi_hid_core_pm_resume(struct device *dev)
+{
+	struct spi_hid *shid = dev_get_drvdata(dev);
+
+	return spi_hid_resume(shid);
+}
+
+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-core.h b/drivers/hid/spi-hid/spi-hid-core.h
index 1d8356f787f3..0b3248aedfce 100644
--- a/drivers/hid/spi-hid/spi-hid-core.h
+++ b/drivers/hid/spi-hid/spi-hid-core.h
@@ -92,6 +92,8 @@ struct spi_hid {
 	struct mutex io_lock;
 
 	struct completion output_done;
+	/* Completed once the device descriptor is received after a reset. */
+	struct completion reset_done;
 
 	u32 report_descriptor_crc32;	/* HID report descriptor crc32 checksum. */
 
diff --git a/drivers/hid/spi-hid/spi-hid-of.c b/drivers/hid/spi-hid/spi-hid-of.c
index 78d0530d2473..605edecc4f7e 100644
--- a/drivers/hid/spi-hid/spi-hid-of.c
+++ b/drivers/hid/spi-hid/spi-hid-of.c
@@ -226,6 +226,7 @@ static struct spi_driver spi_hid_of_driver = {
 	.driver = {
 		.name	= "spi_hid_of",
 		.owner	= THIS_MODULE,
+		.pm	= &spi_hid_core_pm,
 		.of_match_table = 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 f5a5f4d54beb..17b2fdf192ed 100644
--- a/drivers/hid/spi-hid/spi-hid.h
+++ b/drivers/hid/spi-hid/spi-hid.h
@@ -41,5 +41,6 @@ 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 */

-- 
2.56.0.385.gd3acb90ef8-goog