[PATCH v8 0/3] usb: typec: Implement UCSI driver for ChromeOS

[PATCH v8 0/3] usb: typec: Implement UCSI driver for ChromeOS

[Łukasz Bartosik]

This series implements a UCSI ChromeOS EC transport driver. 
The ChromeOS EC is expected to implement UCSI Platform Policy
Manager (PPM).

---
Changes in v8:
- Set .sync_control in cros_ucsi_ops struct to point
to ucsi_sync_control_common().
- Added explanation why complete() is used instead of resume()
in cros_ucsi_pm_ops struct.
- Updated s/miliseconds/milliseconds/.
- Link to v7: https://lore.kernel.org/linux-usb/20241115155234.1587589-1-ukaszb@chromium.org/ 

Changes in v7:
- Dropped the following commits for now as I want to focus
on upstreaming cros_ec_ucsi driver first. Then I will get
back to the topic of trace events and netlink:
  "usb: typec: cros_ec_ucsi: Add trace events"
  "usb: typec: cros_ec_ucsi: Add netlink"
- Squashed "usb: typec: cros_ec_ucsi: Use complete instead of resume"
into "usb: typec: ucsi: Implement ChromeOS UCSI driver".
- Added "usb: typec: cros_ec_ucsi: Recover from write timeouts" commmit.
- Added usage of common functins ucsi_sync_control_common()
and ucsi_notify_common().
- Commits:
  "platform/chrome: Update EC feature flags"
  "mfd: cros_ec: Load cros_ec_ucsi on supported ECs"
  "mfd: cros_ec: Don't load charger with UCSI"
landed in the tree https://git.kernel.org/pub/scm/linux/kernel/git/lee/mfd.git/log/?h=for-mfd-next    
- Link to v6: https://lore.kernel.org/linux-usb/20240910101527.603452-1-ukaszb@chromium.org

Changes in v6:
- Reverted to type names uint*_t in cros_ec_commands.h in order 
to be consistent with type names used in other parts of the file.
- Updated comments in cros_ec_commands.h related to UCSI.
- Added missing sign-offs.
- Fixed memory leak in cros_ucsi_async_control() by moving
ec_params_ucsi_ppm_set request buffer to stack.
- Replaced cros_ucsi_read with cros_ucsi_read_cci in cros_ucsi_work().
- Updated changes in v5, it was missing information related to
commits addition:
  platform/chrome: Update EC feature flags
  usb: typec: cros_ec_ucsi: Use complete instead of resume
  mfd: cros_ec: Load cros_ec_ucsi on supported ECs
  mfd: cros_ec: Don't load charger with UCSI
- Link to v5: https://lore.kernel.org/r/all/20240903163033.3170815-1-ukaszb@chromium.org/

Changes in v5:
- Increased WRITE_TMO_MS to 5000.
- Replaced DRV_NAME with KBUILD_MODNAME.
- Added comments for WRITE_TMO_MS and MAX_EC_DATA_SIZE defines.
- Refactored cros_ucsi_async_control() to dynamically allocate memory
for a message to EC instead of allocating the message on stack.
- Replaced type names uint*_t with u*.
- Removed ret variable in cros_ucsi_work().
- Updated ucsi_operations interface to align with changes introduced in
  v6.11.
- Replaced test_bit() with test_and_clear_bit() in cros_ucsi_work().
- Updated EC feature flags in commit "platform/chrome: Update EC feature
  flags".
- Added new commit "usb: typec: cros_ec_ucsi: Use complete instead
of resume".
- Added trace events in commit "usb: typec: cros_ec_ucsi: Add trace
  events".
- Added netlink in commit "usb: typec: cros_ec_ucsi: Add netlink"
for debugging and testing puropses.
- Added new commit "mfd: cros_ec: Load cros_ec_ucsi on supported ECs".
- Added new commit "mfd: cros_ec: Don't load charger with UCSI".
- Link to v4: https://lore.kernel.org/all/CAB2FV=6We88NrvN8NZYt8NkMFH9N_ZBGyUWVUpGwPdja2X_+NA@mail.gmail.com/T/

Changes in v4:
- Setup notifications before calling ucsi_register.
- Cancel work before destroying driver data.
- Link to v3: https://lore.kernel.org/r/20240403-public-ucsi-h-v3-0-f848e18c8ed2@chromium.org

Changes in v3:
- Moved driver from platform/chrome to usb/typec/ucsi.
- Used id_table instead of MODULE_ALIAS.
- Split EC header changes into seperate commit.
- Fixes from additional internal reviews and kernel bot warnings.
- Link to v2: https://lore.kernel.org/r/20240325-public-ucsi-h-v2-0-a6d716968bb1@chromium.org

Changes in v2:
- No code or commit message changes.
- Added drivers/platform/chrome maintainers for review.

Abhishek Pandit-Subedi (1):
  usb: typec: cros_ec_ucsi: Recover from write timeouts

Pavan Holla (2):
  platform/chrome: Update ChromeOS EC header for UCSI
  usb: typec: ucsi: Implement ChromeOS UCSI driver

 MAINTAINERS                                   |   7 +
 drivers/usb/typec/ucsi/Kconfig                |  13 +
 drivers/usb/typec/ucsi/Makefile               |   1 +
 drivers/usb/typec/ucsi/cros_ec_ucsi.c         | 338 ++++++++++++++++++
 .../linux/platform_data/cros_ec_commands.h    |  28 +-
 5 files changed, 386 insertions(+), 1 deletion(-)
 create mode 100644 drivers/usb/typec/ucsi/cros_ec_ucsi.c

-- 
2.47.0.338.g60cca15819-goog

[PATCH v8 1/3] platform/chrome: Update ChromeOS EC header for UCSI

[Łukasz Bartosik]

From: Pavan Holla <pholla@chromium.org>

Add EC host commands for reading and writing UCSI structures
in the EC. The corresponding kernel driver is cros-ec-ucsi.

Also update PD events supported by the EC.

Acked-by: Tzung-Bi Shih <tzungbi@kernel.org>
Signed-off-by: Pavan Holla <pholla@chromium.org>
Signed-off-by: Łukasz Bartosik <ukaszb@chromium.org>
---
 .../linux/platform_data/cros_ec_commands.h    | 28 ++++++++++++++++++-
 1 file changed, 27 insertions(+), 1 deletion(-)

diff --git a/include/linux/platform_data/cros_ec_commands.h b/include/linux/platform_data/cros_ec_commands.h
index e574b790be6f..8dbb6a769e4f 100644
--- a/include/linux/platform_data/cros_ec_commands.h
+++ b/include/linux/platform_data/cros_ec_commands.h
@@ -5012,8 +5012,11 @@ struct ec_response_pd_status {
 #define PD_EVENT_POWER_CHANGE      BIT(1)
 #define PD_EVENT_IDENTITY_RECEIVED BIT(2)
 #define PD_EVENT_DATA_SWAP         BIT(3)
+#define PD_EVENT_TYPEC             BIT(4)
+#define PD_EVENT_PPM               BIT(5)
+
 struct ec_response_host_event_status {
-	uint32_t status;      /* PD MCU host event status */
+	uint32_t status; /* PD MCU host event status */
 } __ec_align4;
 
 /* Set USB type-C port role and muxes */
@@ -6073,6 +6076,29 @@ struct ec_response_typec_vdm_response {
 
 #undef VDO_MAX_SIZE
 
+/*
+ * UCSI OPM-PPM commands
+ *
+ * These commands are used for communication between OPM and PPM.
+ * Only UCSI3.0 is tested.
+ */
+
+#define EC_CMD_UCSI_PPM_SET 0x0140
+
+/* The data size is stored in the host command protocol header. */
+struct ec_params_ucsi_ppm_set {
+	uint16_t offset;
+	uint8_t data[];
+} __ec_align2;
+
+#define EC_CMD_UCSI_PPM_GET 0x0141
+
+/* For 'GET' sub-commands, data will be returned as a raw payload. */
+struct ec_params_ucsi_ppm_get {
+	uint16_t offset;
+	uint8_t size;
+} __ec_align2;
+
 /*****************************************************************************/
 /* The command range 0x200-0x2FF is reserved for Rotor. */
 
-- 
2.47.0.338.g60cca15819-goog

[PATCH v8 2/3] usb: typec: ucsi: Implement ChromeOS UCSI driver

[Łukasz Bartosik]

From: Pavan Holla <pholla@chromium.org>

Implementation of a UCSI transport driver for ChromeOS.
This driver will be loaded if the ChromeOS EC implements a PPM.

Signed-off-by: Pavan Holla <pholla@chromium.org>
Co-developed-by: Abhishek Pandit-Subedi <abhishekpandit@chromium.org>
Signed-off-by: Abhishek Pandit-Subedi <abhishekpandit@chromium.org>
Co-developed-by: Łukasz Bartosik <ukaszb@chromium.org>
Signed-off-by: Łukasz Bartosik <ukaszb@chromium.org>
---
 MAINTAINERS                           |   7 +
 drivers/usb/typec/ucsi/Kconfig        |  13 ++
 drivers/usb/typec/ucsi/Makefile       |   1 +
 drivers/usb/typec/ucsi/cros_ec_ucsi.c | 252 ++++++++++++++++++++++++++
 4 files changed, 273 insertions(+)
 create mode 100644 drivers/usb/typec/ucsi/cros_ec_ucsi.c

diff --git a/MAINTAINERS b/MAINTAINERS
index b878ddc99f94..b0542223579a 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -5389,6 +5389,13 @@ L:	chrome-platform@lists.linux.dev
 S:	Maintained
 F:	drivers/watchdog/cros_ec_wdt.c
 
+CHROMEOS UCSI DRIVER
+M:	Abhishek Pandit-Subedi <abhishekpandit@chromium.org>
+M:	Łukasz Bartosik <ukaszb@chromium.org>
+L:	chrome-platform@lists.linux.dev
+S:	Maintained
+F:	drivers/usb/typec/ucsi/cros_ec_ucsi.c
+
 CHRONTEL CH7322 CEC DRIVER
 M:	Joe Tessler <jrt@google.com>
 L:	linux-media@vger.kernel.org
diff --git a/drivers/usb/typec/ucsi/Kconfig b/drivers/usb/typec/ucsi/Kconfig
index 680e1b87b152..75559601fe8f 100644
--- a/drivers/usb/typec/ucsi/Kconfig
+++ b/drivers/usb/typec/ucsi/Kconfig
@@ -69,6 +69,19 @@ config UCSI_PMIC_GLINK
 	  To compile the driver as a module, choose M here: the module will be
 	  called ucsi_glink.
 
+config CROS_EC_UCSI
+	tristate "UCSI Driver for ChromeOS EC"
+	depends on MFD_CROS_EC_DEV
+	depends on CROS_USBPD_NOTIFY
+	depends on !EXTCON_TCSS_CROS_EC
+	default MFD_CROS_EC_DEV
+	help
+	  This driver enables UCSI support for a ChromeOS EC. The EC is
+	  expected to implement a PPM.
+
+	  To compile the driver as a module, choose M here: the module
+	  will be called cros_ec_ucsi.
+
 config UCSI_LENOVO_YOGA_C630
 	tristate "UCSI Interface Driver for Lenovo Yoga C630"
 	depends on EC_LENOVO_YOGA_C630
diff --git a/drivers/usb/typec/ucsi/Makefile b/drivers/usb/typec/ucsi/Makefile
index aed41d23887b..be98a879104d 100644
--- a/drivers/usb/typec/ucsi/Makefile
+++ b/drivers/usb/typec/ucsi/Makefile
@@ -21,4 +21,5 @@ obj-$(CONFIG_UCSI_ACPI)			+= ucsi_acpi.o
 obj-$(CONFIG_UCSI_CCG)			+= ucsi_ccg.o
 obj-$(CONFIG_UCSI_STM32G0)		+= ucsi_stm32g0.o
 obj-$(CONFIG_UCSI_PMIC_GLINK)		+= ucsi_glink.o
+obj-$(CONFIG_CROS_EC_UCSI)		+= cros_ec_ucsi.o
 obj-$(CONFIG_UCSI_LENOVO_YOGA_C630)	+= ucsi_yoga_c630.o
diff --git a/drivers/usb/typec/ucsi/cros_ec_ucsi.c b/drivers/usb/typec/ucsi/cros_ec_ucsi.c
new file mode 100644
index 000000000000..c588d9a57643
--- /dev/null
+++ b/drivers/usb/typec/ucsi/cros_ec_ucsi.c
@@ -0,0 +1,252 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * UCSI driver for ChromeOS EC
+ *
+ * Copyright 2024 Google LLC.
+ */
+
+#include <linux/container_of.h>
+#include <linux/dev_printk.h>
+#include <linux/mod_devicetable.h>
+#include <linux/module.h>
+#include <linux/platform_data/cros_ec_commands.h>
+#include <linux/platform_data/cros_usbpd_notify.h>
+#include <linux/platform_data/cros_ec_proto.h>
+#include <linux/platform_device.h>
+#include <linux/slab.h>
+#include <linux/wait.h>
+
+#include "ucsi.h"
+
+/*
+ * Maximum size in bytes of a UCSI message between AP and EC
+ */
+#define MAX_EC_DATA_SIZE	256
+
+/*
+ * Maximum time in milliseconds the cros_ec_ucsi driver
+ * will wait for a response to a command or and ack.
+ */
+#define WRITE_TMO_MS		5000
+
+struct cros_ucsi_data {
+	struct device *dev;
+	struct ucsi *ucsi;
+
+	struct cros_ec_device *ec;
+	struct notifier_block nb;
+	struct work_struct work;
+
+	struct completion complete;
+	unsigned long flags;
+};
+
+static int cros_ucsi_read(struct ucsi *ucsi, unsigned int offset, void *val,
+			  size_t val_len)
+{
+	struct cros_ucsi_data *udata = ucsi_get_drvdata(ucsi);
+	struct ec_params_ucsi_ppm_get req = {
+		.offset = offset,
+		.size = val_len,
+	};
+	int ret;
+
+	if (val_len > MAX_EC_DATA_SIZE) {
+		dev_err(udata->dev, "Can't read %zu bytes. Too big.", val_len);
+		return -EINVAL;
+	}
+
+	ret = cros_ec_cmd(udata->ec, 0, EC_CMD_UCSI_PPM_GET,
+			  &req, sizeof(req), val, val_len);
+	if (ret < 0) {
+		dev_warn(udata->dev, "Failed to send EC message UCSI_PPM_GET: error=%d", ret);
+		return ret;
+	}
+	return 0;
+}
+
+static int cros_ucsi_read_version(struct ucsi *ucsi, u16 *version)
+{
+	return cros_ucsi_read(ucsi, UCSI_VERSION, version, sizeof(*version));
+}
+
+static int cros_ucsi_read_cci(struct ucsi *ucsi, u32 *cci)
+{
+	return cros_ucsi_read(ucsi, UCSI_CCI, cci, sizeof(*cci));
+}
+
+static int cros_ucsi_read_message_in(struct ucsi *ucsi, void *val,
+				     size_t val_len)
+{
+	return cros_ucsi_read(ucsi, UCSI_MESSAGE_IN, val, val_len);
+}
+
+static int cros_ucsi_async_control(struct ucsi *ucsi, u64 cmd)
+{
+	struct cros_ucsi_data *udata = ucsi_get_drvdata(ucsi);
+	u8 ec_buf[sizeof(struct ec_params_ucsi_ppm_set) + sizeof(cmd)];
+	struct ec_params_ucsi_ppm_set *req = (struct ec_params_ucsi_ppm_set *) ec_buf;
+	int ret;
+
+	req->offset = UCSI_CONTROL;
+	memcpy(req->data, &cmd, sizeof(cmd));
+	ret = cros_ec_cmd(udata->ec, 0, EC_CMD_UCSI_PPM_SET,
+			  req, sizeof(ec_buf), NULL, 0);
+	if (ret < 0) {
+		dev_warn(udata->dev, "Failed to send EC message UCSI_PPM_SET: error=%d", ret);
+		return ret;
+	}
+	return 0;
+}
+
+struct ucsi_operations cros_ucsi_ops = {
+	.read_version = cros_ucsi_read_version,
+	.read_cci = cros_ucsi_read_cci,
+	.read_message_in = cros_ucsi_read_message_in,
+	.async_control = cros_ucsi_async_control,
+	.sync_control = ucsi_sync_control_common,
+};
+
+static void cros_ucsi_work(struct work_struct *work)
+{
+	struct cros_ucsi_data *udata = container_of(work, struct cros_ucsi_data, work);
+	u32 cci;
+
+	if (cros_ucsi_read_cci(udata->ucsi, &cci))
+		return;
+
+	ucsi_notify_common(udata->ucsi, cci);
+}
+
+static int cros_ucsi_event(struct notifier_block *nb,
+			   unsigned long host_event, void *_notify)
+{
+	struct cros_ucsi_data *udata = container_of(nb, struct cros_ucsi_data, nb);
+
+	if (!(host_event & PD_EVENT_PPM))
+		return NOTIFY_OK;
+
+	dev_dbg(udata->dev, "UCSI notification received");
+	flush_work(&udata->work);
+	schedule_work(&udata->work);
+
+	return NOTIFY_OK;
+}
+
+static void cros_ucsi_destroy(struct cros_ucsi_data *udata)
+{
+	cros_usbpd_unregister_notify(&udata->nb);
+	cancel_work_sync(&udata->work);
+	ucsi_destroy(udata->ucsi);
+}
+
+static int cros_ucsi_probe(struct platform_device *pdev)
+{
+	struct device *dev = &pdev->dev;
+	struct cros_ec_dev *ec_data = dev_get_drvdata(dev->parent);
+	struct cros_ucsi_data *udata;
+	int ret;
+
+	udata = devm_kzalloc(dev, sizeof(*udata), GFP_KERNEL);
+	if (!udata)
+		return -ENOMEM;
+
+	udata->dev = dev;
+
+	udata->ec = ec_data->ec_dev;
+	if (!udata->ec) {
+		dev_err(dev, "couldn't find parent EC device");
+		return -ENODEV;
+	}
+
+	platform_set_drvdata(pdev, udata);
+
+	INIT_WORK(&udata->work, cros_ucsi_work);
+	init_completion(&udata->complete);
+
+	udata->ucsi = ucsi_create(dev, &cros_ucsi_ops);
+	if (IS_ERR(udata->ucsi)) {
+		dev_err(dev, "failed to allocate UCSI instance");
+		return PTR_ERR(udata->ucsi);
+	}
+
+	ucsi_set_drvdata(udata->ucsi, udata);
+
+	udata->nb.notifier_call = cros_ucsi_event;
+	ret = cros_usbpd_register_notify(&udata->nb);
+	if (ret) {
+		dev_err(dev, "failed to register notifier: error=%d", ret);
+		ucsi_destroy(udata->ucsi);
+		return ret;
+	}
+
+	ret = ucsi_register(udata->ucsi);
+	if (ret) {
+		dev_err(dev, "failed to register UCSI: error=%d", ret);
+		cros_ucsi_destroy(udata);
+		return ret;
+	}
+
+	return 0;
+}
+
+static void cros_ucsi_remove(struct platform_device *dev)
+{
+	struct cros_ucsi_data *udata = platform_get_drvdata(dev);
+
+	ucsi_unregister(udata->ucsi);
+	cros_ucsi_destroy(udata);
+}
+
+static int __maybe_unused cros_ucsi_suspend(struct device *dev)
+{
+	struct cros_ucsi_data *udata = dev_get_drvdata(dev);
+
+	cancel_work_sync(&udata->work);
+
+	return 0;
+}
+
+static void __maybe_unused cros_ucsi_complete(struct device *dev)
+{
+	struct cros_ucsi_data *udata = dev_get_drvdata(dev);
+
+	ucsi_resume(udata->ucsi);
+}
+
+/*
+ * UCSI protocol is also used on ChromeOS platforms which reply on
+ * cros_ec_lpc.c driver for communication with embedded controller (EC).
+ * On such platforms communication with the EC is not available until
+ * the .complete() callback of the cros_ec_lpc driver is executed.
+ * For this reason we delay ucsi_resume() until the .complete() stage
+ * otherwise UCSI SET_NOTIFICATION_ENABLE command will fail and we won't
+ * receive any UCSI notifications from the EC where PPM is implemented.
+ */
+static const struct dev_pm_ops cros_ucsi_pm_ops = {
+#ifdef CONFIG_PM_SLEEP
+	.suspend = cros_ucsi_suspend,
+	.complete = cros_ucsi_complete,
+#endif
+};
+
+static const struct platform_device_id cros_ucsi_id[] = {
+	{ KBUILD_MODNAME, 0 },
+	{}
+};
+MODULE_DEVICE_TABLE(platform, cros_ucsi_id);
+
+static struct platform_driver cros_ucsi_driver = {
+	.driver = {
+		.name = KBUILD_MODNAME,
+		.pm = &cros_ucsi_pm_ops,
+	},
+	.id_table = cros_ucsi_id,
+	.probe = cros_ucsi_probe,
+	.remove = cros_ucsi_remove,
+};
+
+module_platform_driver(cros_ucsi_driver);
+
+MODULE_LICENSE("GPL");
+MODULE_DESCRIPTION("UCSI driver for ChromeOS EC");
-- 
2.47.0.338.g60cca15819-goog

[PATCH v8 3/3] usb: typec: cros_ec_ucsi: Recover from write timeouts

[Łukasz Bartosik]

From: Abhishek Pandit-Subedi <abhishekpandit@chromium.org>

In a suspend-resume edge case, the OPM is timing out in ucsi_resume and
the PPM is getting stuck waiting for a command complete ack. Add a write
timeout recovery task that will get us out of this state.

Signed-off-by: Abhishek Pandit-Subedi <abhishekpandit@chromium.org>
Signed-off-by: Łukasz Bartosik <ukaszb@chromium.org>
---
 drivers/usb/typec/ucsi/cros_ec_ucsi.c | 88 ++++++++++++++++++++++++++-
 1 file changed, 87 insertions(+), 1 deletion(-)

diff --git a/drivers/usb/typec/ucsi/cros_ec_ucsi.c b/drivers/usb/typec/ucsi/cros_ec_ucsi.c
index c588d9a57643..6daf61e7e62a 100644
--- a/drivers/usb/typec/ucsi/cros_ec_ucsi.c
+++ b/drivers/usb/typec/ucsi/cros_ec_ucsi.c
@@ -7,6 +7,7 @@
 
 #include <linux/container_of.h>
 #include <linux/dev_printk.h>
+#include <linux/jiffies.h>
 #include <linux/mod_devicetable.h>
 #include <linux/module.h>
 #include <linux/platform_data/cros_ec_commands.h>
@@ -29,6 +30,9 @@
  */
 #define WRITE_TMO_MS		5000
 
+/* Number of times to attempt recovery from a write timeout before giving up. */
+#define WRITE_TMO_CTR_MAX	5
+
 struct cros_ucsi_data {
 	struct device *dev;
 	struct ucsi *ucsi;
@@ -36,6 +40,8 @@ struct cros_ucsi_data {
 	struct cros_ec_device *ec;
 	struct notifier_block nb;
 	struct work_struct work;
+	struct delayed_work write_tmo;
+	int tmo_counter;
 
 	struct completion complete;
 	unsigned long flags;
@@ -99,12 +105,43 @@ static int cros_ucsi_async_control(struct ucsi *ucsi, u64 cmd)
 	return 0;
 }
 
+static int cros_ucsi_sync_control(struct ucsi *ucsi, u64 cmd)
+{
+	struct cros_ucsi_data *udata = ucsi_get_drvdata(ucsi);
+	int ret;
+
+	ret = ucsi_sync_control_common(ucsi, cmd);
+	if (ret)
+		goto out;
+
+	/* Successful write. Cancel any pending recovery work. */
+	cancel_delayed_work_sync(&udata->write_tmo);
+
+	return 0;
+out:
+	/* EC may return -EBUSY if CCI.busy is set. Convert this to a timeout.
+	 */
+	if (ret == -EBUSY)
+		ret = -ETIMEDOUT;
+
+	/* Schedule recovery attempt when we timeout or tried to send a command
+	 * while still busy.
+	 */
+	if (ret == -ETIMEDOUT) {
+		cancel_delayed_work_sync(&udata->write_tmo);
+		schedule_delayed_work(&udata->write_tmo,
+				      msecs_to_jiffies(WRITE_TMO_MS));
+	}
+
+	return ret;
+}
+
 struct ucsi_operations cros_ucsi_ops = {
 	.read_version = cros_ucsi_read_version,
 	.read_cci = cros_ucsi_read_cci,
 	.read_message_in = cros_ucsi_read_message_in,
 	.async_control = cros_ucsi_async_control,
-	.sync_control = ucsi_sync_control_common,
+	.sync_control = cros_ucsi_sync_control,
 };
 
 static void cros_ucsi_work(struct work_struct *work)
@@ -118,6 +155,54 @@ static void cros_ucsi_work(struct work_struct *work)
 	ucsi_notify_common(udata->ucsi, cci);
 }
 
+static void cros_ucsi_write_timeout(struct work_struct *work)
+{
+	struct cros_ucsi_data *udata =
+		container_of(work, struct cros_ucsi_data, write_tmo.work);
+	u32 cci;
+	u64 cmd;
+
+	if (cros_ucsi_read(udata->ucsi, UCSI_CCI, &cci, sizeof(cci))) {
+		dev_err(udata->dev,
+			"Reading CCI failed; no write timeout recovery possible.");
+		return;
+	}
+
+	if (cci & UCSI_CCI_BUSY) {
+		udata->tmo_counter++;
+
+		if (udata->tmo_counter <= WRITE_TMO_CTR_MAX)
+			schedule_delayed_work(&udata->write_tmo,
+					      msecs_to_jiffies(WRITE_TMO_MS));
+		else
+			dev_err(udata->dev,
+				"PPM unresponsive - too many write timeouts.");
+
+		return;
+	}
+
+	/* No longer busy means we can reset our timeout counter. */
+	udata->tmo_counter = 0;
+
+	/* Need to ack previous command which may have timed out. */
+	if (cci & UCSI_CCI_COMMAND_COMPLETE) {
+		cmd = UCSI_ACK_CC_CI | UCSI_ACK_COMMAND_COMPLETE;
+		cros_ucsi_async_control(udata->ucsi, &cmd);
+
+		/* Check again after a few seconds that the system has
+		 * recovered to make sure our async write above was successful.
+		 */
+		schedule_delayed_work(&udata->write_tmo,
+				      msecs_to_jiffies(WRITE_TMO_MS));
+		return;
+	}
+
+	/* We recovered from a previous timeout. Treat this as a recovery from
+	 * suspend and call resume.
+	 */
+	ucsi_resume(udata->ucsi);
+}
+
 static int cros_ucsi_event(struct notifier_block *nb,
 			   unsigned long host_event, void *_notify)
 {
@@ -162,6 +247,7 @@ static int cros_ucsi_probe(struct platform_device *pdev)
 	platform_set_drvdata(pdev, udata);
 
 	INIT_WORK(&udata->work, cros_ucsi_work);
+	INIT_DELAYED_WORK(&udata->write_tmo, cros_ucsi_write_timeout);
 	init_completion(&udata->complete);
 
 	udata->ucsi = ucsi_create(dev, &cros_ucsi_ops);
-- 
2.47.0.338.g60cca15819-goog

Re: [PATCH v8 2/3] usb: typec: ucsi: Implement ChromeOS UCSI driver

[Heikki Krogerus]

On Thu, Nov 28, 2024 at 11:20:34PM +0000, Łukasz Bartosik wrote:
> From: Pavan Holla <pholla@chromium.org>
> 
> Implementation of a UCSI transport driver for ChromeOS.
> This driver will be loaded if the ChromeOS EC implements a PPM.
> 
> Signed-off-by: Pavan Holla <pholla@chromium.org>
> Co-developed-by: Abhishek Pandit-Subedi <abhishekpandit@chromium.org>
> Signed-off-by: Abhishek Pandit-Subedi <abhishekpandit@chromium.org>
> Co-developed-by: Łukasz Bartosik <ukaszb@chromium.org>
> Signed-off-by: Łukasz Bartosik <ukaszb@chromium.org>

Reviewed-by: Heikki Krogerus <heikki.krogerus@linux.intel.com>

> ---
>  MAINTAINERS                           |   7 +
>  drivers/usb/typec/ucsi/Kconfig        |  13 ++
>  drivers/usb/typec/ucsi/Makefile       |   1 +
>  drivers/usb/typec/ucsi/cros_ec_ucsi.c | 252 ++++++++++++++++++++++++++
>  4 files changed, 273 insertions(+)
>  create mode 100644 drivers/usb/typec/ucsi/cros_ec_ucsi.c
> 
> diff --git a/MAINTAINERS b/MAINTAINERS
> index b878ddc99f94..b0542223579a 100644
> --- a/MAINTAINERS
> +++ b/MAINTAINERS
> @@ -5389,6 +5389,13 @@ L:	chrome-platform@lists.linux.dev
>  S:	Maintained
>  F:	drivers/watchdog/cros_ec_wdt.c
>  
> +CHROMEOS UCSI DRIVER
> +M:	Abhishek Pandit-Subedi <abhishekpandit@chromium.org>
> +M:	Łukasz Bartosik <ukaszb@chromium.org>
> +L:	chrome-platform@lists.linux.dev
> +S:	Maintained
> +F:	drivers/usb/typec/ucsi/cros_ec_ucsi.c
> +
>  CHRONTEL CH7322 CEC DRIVER
>  M:	Joe Tessler <jrt@google.com>
>  L:	linux-media@vger.kernel.org
> diff --git a/drivers/usb/typec/ucsi/Kconfig b/drivers/usb/typec/ucsi/Kconfig
> index 680e1b87b152..75559601fe8f 100644
> --- a/drivers/usb/typec/ucsi/Kconfig
> +++ b/drivers/usb/typec/ucsi/Kconfig
> @@ -69,6 +69,19 @@ config UCSI_PMIC_GLINK
>  	  To compile the driver as a module, choose M here: the module will be
>  	  called ucsi_glink.
>  
> +config CROS_EC_UCSI
> +	tristate "UCSI Driver for ChromeOS EC"
> +	depends on MFD_CROS_EC_DEV
> +	depends on CROS_USBPD_NOTIFY
> +	depends on !EXTCON_TCSS_CROS_EC
> +	default MFD_CROS_EC_DEV
> +	help
> +	  This driver enables UCSI support for a ChromeOS EC. The EC is
> +	  expected to implement a PPM.
> +
> +	  To compile the driver as a module, choose M here: the module
> +	  will be called cros_ec_ucsi.
> +
>  config UCSI_LENOVO_YOGA_C630
>  	tristate "UCSI Interface Driver for Lenovo Yoga C630"
>  	depends on EC_LENOVO_YOGA_C630
> diff --git a/drivers/usb/typec/ucsi/Makefile b/drivers/usb/typec/ucsi/Makefile
> index aed41d23887b..be98a879104d 100644
> --- a/drivers/usb/typec/ucsi/Makefile
> +++ b/drivers/usb/typec/ucsi/Makefile
> @@ -21,4 +21,5 @@ obj-$(CONFIG_UCSI_ACPI)			+= ucsi_acpi.o
>  obj-$(CONFIG_UCSI_CCG)			+= ucsi_ccg.o
>  obj-$(CONFIG_UCSI_STM32G0)		+= ucsi_stm32g0.o
>  obj-$(CONFIG_UCSI_PMIC_GLINK)		+= ucsi_glink.o
> +obj-$(CONFIG_CROS_EC_UCSI)		+= cros_ec_ucsi.o
>  obj-$(CONFIG_UCSI_LENOVO_YOGA_C630)	+= ucsi_yoga_c630.o
> diff --git a/drivers/usb/typec/ucsi/cros_ec_ucsi.c b/drivers/usb/typec/ucsi/cros_ec_ucsi.c
> new file mode 100644
> index 000000000000..c588d9a57643
> --- /dev/null
> +++ b/drivers/usb/typec/ucsi/cros_ec_ucsi.c
> @@ -0,0 +1,252 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/*
> + * UCSI driver for ChromeOS EC
> + *
> + * Copyright 2024 Google LLC.
> + */
> +
> +#include <linux/container_of.h>
> +#include <linux/dev_printk.h>
> +#include <linux/mod_devicetable.h>
> +#include <linux/module.h>
> +#include <linux/platform_data/cros_ec_commands.h>
> +#include <linux/platform_data/cros_usbpd_notify.h>
> +#include <linux/platform_data/cros_ec_proto.h>
> +#include <linux/platform_device.h>
> +#include <linux/slab.h>
> +#include <linux/wait.h>
> +
> +#include "ucsi.h"
> +
> +/*
> + * Maximum size in bytes of a UCSI message between AP and EC
> + */
> +#define MAX_EC_DATA_SIZE	256
> +
> +/*
> + * Maximum time in milliseconds the cros_ec_ucsi driver
> + * will wait for a response to a command or and ack.
> + */
> +#define WRITE_TMO_MS		5000
> +
> +struct cros_ucsi_data {
> +	struct device *dev;
> +	struct ucsi *ucsi;
> +
> +	struct cros_ec_device *ec;
> +	struct notifier_block nb;
> +	struct work_struct work;
> +
> +	struct completion complete;
> +	unsigned long flags;
> +};
> +
> +static int cros_ucsi_read(struct ucsi *ucsi, unsigned int offset, void *val,
> +			  size_t val_len)
> +{
> +	struct cros_ucsi_data *udata = ucsi_get_drvdata(ucsi);
> +	struct ec_params_ucsi_ppm_get req = {
> +		.offset = offset,
> +		.size = val_len,
> +	};
> +	int ret;
> +
> +	if (val_len > MAX_EC_DATA_SIZE) {
> +		dev_err(udata->dev, "Can't read %zu bytes. Too big.", val_len);
> +		return -EINVAL;
> +	}
> +
> +	ret = cros_ec_cmd(udata->ec, 0, EC_CMD_UCSI_PPM_GET,
> +			  &req, sizeof(req), val, val_len);
> +	if (ret < 0) {
> +		dev_warn(udata->dev, "Failed to send EC message UCSI_PPM_GET: error=%d", ret);
> +		return ret;
> +	}
> +	return 0;
> +}
> +
> +static int cros_ucsi_read_version(struct ucsi *ucsi, u16 *version)
> +{
> +	return cros_ucsi_read(ucsi, UCSI_VERSION, version, sizeof(*version));
> +}
> +
> +static int cros_ucsi_read_cci(struct ucsi *ucsi, u32 *cci)
> +{
> +	return cros_ucsi_read(ucsi, UCSI_CCI, cci, sizeof(*cci));
> +}
> +
> +static int cros_ucsi_read_message_in(struct ucsi *ucsi, void *val,
> +				     size_t val_len)
> +{
> +	return cros_ucsi_read(ucsi, UCSI_MESSAGE_IN, val, val_len);
> +}
> +
> +static int cros_ucsi_async_control(struct ucsi *ucsi, u64 cmd)
> +{
> +	struct cros_ucsi_data *udata = ucsi_get_drvdata(ucsi);
> +	u8 ec_buf[sizeof(struct ec_params_ucsi_ppm_set) + sizeof(cmd)];
> +	struct ec_params_ucsi_ppm_set *req = (struct ec_params_ucsi_ppm_set *) ec_buf;
> +	int ret;
> +
> +	req->offset = UCSI_CONTROL;
> +	memcpy(req->data, &cmd, sizeof(cmd));
> +	ret = cros_ec_cmd(udata->ec, 0, EC_CMD_UCSI_PPM_SET,
> +			  req, sizeof(ec_buf), NULL, 0);
> +	if (ret < 0) {
> +		dev_warn(udata->dev, "Failed to send EC message UCSI_PPM_SET: error=%d", ret);
> +		return ret;
> +	}
> +	return 0;
> +}
> +
> +struct ucsi_operations cros_ucsi_ops = {
> +	.read_version = cros_ucsi_read_version,
> +	.read_cci = cros_ucsi_read_cci,
> +	.read_message_in = cros_ucsi_read_message_in,
> +	.async_control = cros_ucsi_async_control,
> +	.sync_control = ucsi_sync_control_common,
> +};
> +
> +static void cros_ucsi_work(struct work_struct *work)
> +{
> +	struct cros_ucsi_data *udata = container_of(work, struct cros_ucsi_data, work);
> +	u32 cci;
> +
> +	if (cros_ucsi_read_cci(udata->ucsi, &cci))
> +		return;
> +
> +	ucsi_notify_common(udata->ucsi, cci);
> +}
> +
> +static int cros_ucsi_event(struct notifier_block *nb,
> +			   unsigned long host_event, void *_notify)
> +{
> +	struct cros_ucsi_data *udata = container_of(nb, struct cros_ucsi_data, nb);
> +
> +	if (!(host_event & PD_EVENT_PPM))
> +		return NOTIFY_OK;
> +
> +	dev_dbg(udata->dev, "UCSI notification received");
> +	flush_work(&udata->work);
> +	schedule_work(&udata->work);
> +
> +	return NOTIFY_OK;
> +}
> +
> +static void cros_ucsi_destroy(struct cros_ucsi_data *udata)
> +{
> +	cros_usbpd_unregister_notify(&udata->nb);
> +	cancel_work_sync(&udata->work);
> +	ucsi_destroy(udata->ucsi);
> +}
> +
> +static int cros_ucsi_probe(struct platform_device *pdev)
> +{
> +	struct device *dev = &pdev->dev;
> +	struct cros_ec_dev *ec_data = dev_get_drvdata(dev->parent);
> +	struct cros_ucsi_data *udata;
> +	int ret;
> +
> +	udata = devm_kzalloc(dev, sizeof(*udata), GFP_KERNEL);
> +	if (!udata)
> +		return -ENOMEM;
> +
> +	udata->dev = dev;
> +
> +	udata->ec = ec_data->ec_dev;
> +	if (!udata->ec) {
> +		dev_err(dev, "couldn't find parent EC device");
> +		return -ENODEV;
> +	}
> +
> +	platform_set_drvdata(pdev, udata);
> +
> +	INIT_WORK(&udata->work, cros_ucsi_work);
> +	init_completion(&udata->complete);
> +
> +	udata->ucsi = ucsi_create(dev, &cros_ucsi_ops);
> +	if (IS_ERR(udata->ucsi)) {
> +		dev_err(dev, "failed to allocate UCSI instance");
> +		return PTR_ERR(udata->ucsi);
> +	}
> +
> +	ucsi_set_drvdata(udata->ucsi, udata);
> +
> +	udata->nb.notifier_call = cros_ucsi_event;
> +	ret = cros_usbpd_register_notify(&udata->nb);
> +	if (ret) {
> +		dev_err(dev, "failed to register notifier: error=%d", ret);
> +		ucsi_destroy(udata->ucsi);
> +		return ret;
> +	}
> +
> +	ret = ucsi_register(udata->ucsi);
> +	if (ret) {
> +		dev_err(dev, "failed to register UCSI: error=%d", ret);
> +		cros_ucsi_destroy(udata);
> +		return ret;
> +	}
> +
> +	return 0;
> +}
> +
> +static void cros_ucsi_remove(struct platform_device *dev)
> +{
> +	struct cros_ucsi_data *udata = platform_get_drvdata(dev);
> +
> +	ucsi_unregister(udata->ucsi);
> +	cros_ucsi_destroy(udata);
> +}
> +
> +static int __maybe_unused cros_ucsi_suspend(struct device *dev)
> +{
> +	struct cros_ucsi_data *udata = dev_get_drvdata(dev);
> +
> +	cancel_work_sync(&udata->work);
> +
> +	return 0;
> +}
> +
> +static void __maybe_unused cros_ucsi_complete(struct device *dev)
> +{
> +	struct cros_ucsi_data *udata = dev_get_drvdata(dev);
> +
> +	ucsi_resume(udata->ucsi);
> +}
> +
> +/*
> + * UCSI protocol is also used on ChromeOS platforms which reply on
> + * cros_ec_lpc.c driver for communication with embedded controller (EC).
> + * On such platforms communication with the EC is not available until
> + * the .complete() callback of the cros_ec_lpc driver is executed.
> + * For this reason we delay ucsi_resume() until the .complete() stage
> + * otherwise UCSI SET_NOTIFICATION_ENABLE command will fail and we won't
> + * receive any UCSI notifications from the EC where PPM is implemented.
> + */
> +static const struct dev_pm_ops cros_ucsi_pm_ops = {
> +#ifdef CONFIG_PM_SLEEP
> +	.suspend = cros_ucsi_suspend,
> +	.complete = cros_ucsi_complete,
> +#endif
> +};
> +
> +static const struct platform_device_id cros_ucsi_id[] = {
> +	{ KBUILD_MODNAME, 0 },
> +	{}
> +};
> +MODULE_DEVICE_TABLE(platform, cros_ucsi_id);
> +
> +static struct platform_driver cros_ucsi_driver = {
> +	.driver = {
> +		.name = KBUILD_MODNAME,
> +		.pm = &cros_ucsi_pm_ops,
> +	},
> +	.id_table = cros_ucsi_id,
> +	.probe = cros_ucsi_probe,
> +	.remove = cros_ucsi_remove,
> +};
> +
> +module_platform_driver(cros_ucsi_driver);
> +
> +MODULE_LICENSE("GPL");
> +MODULE_DESCRIPTION("UCSI driver for ChromeOS EC");
> -- 
> 2.47.0.338.g60cca15819-goog

-- 
heikki

Re: [PATCH v8 3/3] usb: typec: cros_ec_ucsi: Recover from write timeouts

[Heikki Krogerus]

Hi Łukasz,

On Thu, Nov 28, 2024 at 11:20:35PM +0000, Łukasz Bartosik wrote:
> From: Abhishek Pandit-Subedi <abhishekpandit@chromium.org>
> 
> In a suspend-resume edge case, the OPM is timing out in ucsi_resume and
> the PPM is getting stuck waiting for a command complete ack. Add a write
> timeout recovery task that will get us out of this state.

Sorry, I did not realise this before, but this is in practice a fix
(or workaround) to the driver that you just introduced in the previous
patch. Please merge it into that.

> Signed-off-by: Abhishek Pandit-Subedi <abhishekpandit@chromium.org>
> Signed-off-by: Łukasz Bartosik <ukaszb@chromium.org>
> ---
>  drivers/usb/typec/ucsi/cros_ec_ucsi.c | 88 ++++++++++++++++++++++++++-
>  1 file changed, 87 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/usb/typec/ucsi/cros_ec_ucsi.c b/drivers/usb/typec/ucsi/cros_ec_ucsi.c
> index c588d9a57643..6daf61e7e62a 100644
> --- a/drivers/usb/typec/ucsi/cros_ec_ucsi.c
> +++ b/drivers/usb/typec/ucsi/cros_ec_ucsi.c
> @@ -7,6 +7,7 @@
>  
>  #include <linux/container_of.h>
>  #include <linux/dev_printk.h>
> +#include <linux/jiffies.h>
>  #include <linux/mod_devicetable.h>
>  #include <linux/module.h>
>  #include <linux/platform_data/cros_ec_commands.h>
> @@ -29,6 +30,9 @@
>   */
>  #define WRITE_TMO_MS		5000
>  
> +/* Number of times to attempt recovery from a write timeout before giving up. */
> +#define WRITE_TMO_CTR_MAX	5
> +
>  struct cros_ucsi_data {
>  	struct device *dev;
>  	struct ucsi *ucsi;
> @@ -36,6 +40,8 @@ struct cros_ucsi_data {
>  	struct cros_ec_device *ec;
>  	struct notifier_block nb;
>  	struct work_struct work;
> +	struct delayed_work write_tmo;
> +	int tmo_counter;
>  
>  	struct completion complete;
>  	unsigned long flags;
> @@ -99,12 +105,43 @@ static int cros_ucsi_async_control(struct ucsi *ucsi, u64 cmd)
>  	return 0;
>  }
>  
> +static int cros_ucsi_sync_control(struct ucsi *ucsi, u64 cmd)
> +{
> +	struct cros_ucsi_data *udata = ucsi_get_drvdata(ucsi);
> +	int ret;
> +
> +	ret = ucsi_sync_control_common(ucsi, cmd);
> +	if (ret)
> +		goto out;
> +
> +	/* Successful write. Cancel any pending recovery work. */
> +	cancel_delayed_work_sync(&udata->write_tmo);
> +
> +	return 0;
> +out:

This label looks a bit unnecessary to me. How about a switch statement?

	ret = ucsi_sync_control_common(ucsi, cmd);
        switch (ret) {
        case -EBUSY:
        case -ETIMEDOUT:
		cancel_delayed_work_sync(&udata->write_tmo);
		schedule_delayed_work(&udata->write_tmo, msecs_to_jiffies(WRITE_TMO_MS));
                break;
        case 0:
                cancel_delayed_work_sync(&udata->write_tmo);
                break;
        }

        return ret;

> +	/* EC may return -EBUSY if CCI.busy is set. Convert this to a timeout.
> +	 */
> +	if (ret == -EBUSY)
> +		ret = -ETIMEDOUT;
> +
> +	/* Schedule recovery attempt when we timeout or tried to send a command
> +	 * while still busy.
> +	 */
> +	if (ret == -ETIMEDOUT) {
> +		cancel_delayed_work_sync(&udata->write_tmo);
> +		schedule_delayed_work(&udata->write_tmo,
> +				      msecs_to_jiffies(WRITE_TMO_MS));
> +	}
> +
> +	return ret;
> +}
> +
>  struct ucsi_operations cros_ucsi_ops = {
>  	.read_version = cros_ucsi_read_version,
>  	.read_cci = cros_ucsi_read_cci,
>  	.read_message_in = cros_ucsi_read_message_in,
>  	.async_control = cros_ucsi_async_control,
> -	.sync_control = ucsi_sync_control_common,
> +	.sync_control = cros_ucsi_sync_control,
>  };
>  
>  static void cros_ucsi_work(struct work_struct *work)
> @@ -118,6 +155,54 @@ static void cros_ucsi_work(struct work_struct *work)
>  	ucsi_notify_common(udata->ucsi, cci);
>  }
>  
> +static void cros_ucsi_write_timeout(struct work_struct *work)
> +{
> +	struct cros_ucsi_data *udata =
> +		container_of(work, struct cros_ucsi_data, write_tmo.work);
> +	u32 cci;
> +	u64 cmd;
> +
> +	if (cros_ucsi_read(udata->ucsi, UCSI_CCI, &cci, sizeof(cci))) {
> +		dev_err(udata->dev,
> +			"Reading CCI failed; no write timeout recovery possible.");
> +		return;
> +	}
> +
> +	if (cci & UCSI_CCI_BUSY) {
> +		udata->tmo_counter++;
> +
> +		if (udata->tmo_counter <= WRITE_TMO_CTR_MAX)
> +			schedule_delayed_work(&udata->write_tmo,
> +					      msecs_to_jiffies(WRITE_TMO_MS));
> +		else
> +			dev_err(udata->dev,
> +				"PPM unresponsive - too many write timeouts.");
> +
> +		return;
> +	}
> +
> +	/* No longer busy means we can reset our timeout counter. */
> +	udata->tmo_counter = 0;
> +
> +	/* Need to ack previous command which may have timed out. */
> +	if (cci & UCSI_CCI_COMMAND_COMPLETE) {
> +		cmd = UCSI_ACK_CC_CI | UCSI_ACK_COMMAND_COMPLETE;
> +		cros_ucsi_async_control(udata->ucsi, &cmd);
> +
> +		/* Check again after a few seconds that the system has
> +		 * recovered to make sure our async write above was successful.
> +		 */
> +		schedule_delayed_work(&udata->write_tmo,
> +				      msecs_to_jiffies(WRITE_TMO_MS));
> +		return;
> +	}
> +
> +	/* We recovered from a previous timeout. Treat this as a recovery from
> +	 * suspend and call resume.
> +	 */
> +	ucsi_resume(udata->ucsi);
> +}
> +
>  static int cros_ucsi_event(struct notifier_block *nb,
>  			   unsigned long host_event, void *_notify)
>  {
> @@ -162,6 +247,7 @@ static int cros_ucsi_probe(struct platform_device *pdev)
>  	platform_set_drvdata(pdev, udata);
>  
>  	INIT_WORK(&udata->work, cros_ucsi_work);
> +	INIT_DELAYED_WORK(&udata->write_tmo, cros_ucsi_write_timeout);
>  	init_completion(&udata->complete);
>  
>  	udata->ucsi = ucsi_create(dev, &cros_ucsi_ops);

thanks,

-- 
heikki

Re: [PATCH v8 3/3] usb: typec: cros_ec_ucsi: Recover from write timeouts

[Łukasz Bartosik]

On Mon, Dec 2, 2024 at 3:06 PM Heikki Krogerus
<heikki.krogerus@linux.intel.com> wrote:
>
> Hi Łukasz,
>
> On Thu, Nov 28, 2024 at 11:20:35PM +0000, Łukasz Bartosik wrote:
> > From: Abhishek Pandit-Subedi <abhishekpandit@chromium.org>
> >
> > In a suspend-resume edge case, the OPM is timing out in ucsi_resume and
> > the PPM is getting stuck waiting for a command complete ack. Add a write
> > timeout recovery task that will get us out of this state.
>
> Sorry, I did not realise this before, but this is in practice a fix
> (or workaround) to the driver that you just introduced in the previous
> patch. Please merge it into that.
>

Hi Heikki,

Yes I will merge it. I deliberately sent it as a separate commit for
review so that
it would be easier to see the changes.

> > Signed-off-by: Abhishek Pandit-Subedi <abhishekpandit@chromium.org>
> > Signed-off-by: Łukasz Bartosik <ukaszb@chromium.org>
> > ---
> >  drivers/usb/typec/ucsi/cros_ec_ucsi.c | 88 ++++++++++++++++++++++++++-
> >  1 file changed, 87 insertions(+), 1 deletion(-)
> >
> > diff --git a/drivers/usb/typec/ucsi/cros_ec_ucsi.c b/drivers/usb/typec/ucsi/cros_ec_ucsi.c
> > index c588d9a57643..6daf61e7e62a 100644
> > --- a/drivers/usb/typec/ucsi/cros_ec_ucsi.c
> > +++ b/drivers/usb/typec/ucsi/cros_ec_ucsi.c
> > @@ -7,6 +7,7 @@
> >
> >  #include <linux/container_of.h>
> >  #include <linux/dev_printk.h>
> > +#include <linux/jiffies.h>
> >  #include <linux/mod_devicetable.h>
> >  #include <linux/module.h>
> >  #include <linux/platform_data/cros_ec_commands.h>
> > @@ -29,6 +30,9 @@
> >   */
> >  #define WRITE_TMO_MS         5000
> >
> > +/* Number of times to attempt recovery from a write timeout before giving up. */
> > +#define WRITE_TMO_CTR_MAX    5
> > +
> >  struct cros_ucsi_data {
> >       struct device *dev;
> >       struct ucsi *ucsi;
> > @@ -36,6 +40,8 @@ struct cros_ucsi_data {
> >       struct cros_ec_device *ec;
> >       struct notifier_block nb;
> >       struct work_struct work;
> > +     struct delayed_work write_tmo;
> > +     int tmo_counter;
> >
> >       struct completion complete;
> >       unsigned long flags;
> > @@ -99,12 +105,43 @@ static int cros_ucsi_async_control(struct ucsi *ucsi, u64 cmd)
> >       return 0;
> >  }
> >
> > +static int cros_ucsi_sync_control(struct ucsi *ucsi, u64 cmd)
> > +{
> > +     struct cros_ucsi_data *udata = ucsi_get_drvdata(ucsi);
> > +     int ret;
> > +
> > +     ret = ucsi_sync_control_common(ucsi, cmd);
> > +     if (ret)
> > +             goto out;
> > +
> > +     /* Successful write. Cancel any pending recovery work. */
> > +     cancel_delayed_work_sync(&udata->write_tmo);
> > +
> > +     return 0;
> > +out:
>
> This label looks a bit unnecessary to me. How about a switch statement?
>

Good point. I will rework this part of the code to use switch.

Thanks,
Łukasz

>         ret = ucsi_sync_control_common(ucsi, cmd);
>         switch (ret) {
>         case -EBUSY:
>         case -ETIMEDOUT:
>                 cancel_delayed_work_sync(&udata->write_tmo);
>                 schedule_delayed_work(&udata->write_tmo, msecs_to_jiffies(WRITE_TMO_MS));
>                 break;
>         case 0:
>                 cancel_delayed_work_sync(&udata->write_tmo);
>                 break;
>         }
>
>         return ret;
>
> > +     /* EC may return -EBUSY if CCI.busy is set. Convert this to a timeout.
> > +      */
> > +     if (ret == -EBUSY)
> > +             ret = -ETIMEDOUT;
> > +
> > +     /* Schedule recovery attempt when we timeout or tried to send a command
> > +      * while still busy.
> > +      */
> > +     if (ret == -ETIMEDOUT) {
> > +             cancel_delayed_work_sync(&udata->write_tmo);
> > +             schedule_delayed_work(&udata->write_tmo,
> > +                                   msecs_to_jiffies(WRITE_TMO_MS));
> > +     }
> > +
> > +     return ret;
> > +}
> > +
> >  struct ucsi_operations cros_ucsi_ops = {
> >       .read_version = cros_ucsi_read_version,
> >       .read_cci = cros_ucsi_read_cci,
> >       .read_message_in = cros_ucsi_read_message_in,
> >       .async_control = cros_ucsi_async_control,
> > -     .sync_control = ucsi_sync_control_common,
> > +     .sync_control = cros_ucsi_sync_control,
> >  };
> >
> >  static void cros_ucsi_work(struct work_struct *work)
> > @@ -118,6 +155,54 @@ static void cros_ucsi_work(struct work_struct *work)
> >       ucsi_notify_common(udata->ucsi, cci);
> >  }
> >
> > +static void cros_ucsi_write_timeout(struct work_struct *work)
> > +{
> > +     struct cros_ucsi_data *udata =
> > +             container_of(work, struct cros_ucsi_data, write_tmo.work);
> > +     u32 cci;
> > +     u64 cmd;
> > +
> > +     if (cros_ucsi_read(udata->ucsi, UCSI_CCI, &cci, sizeof(cci))) {
> > +             dev_err(udata->dev,
> > +                     "Reading CCI failed; no write timeout recovery possible.");
> > +             return;
> > +     }
> > +
> > +     if (cci & UCSI_CCI_BUSY) {
> > +             udata->tmo_counter++;
> > +
> > +             if (udata->tmo_counter <= WRITE_TMO_CTR_MAX)
> > +                     schedule_delayed_work(&udata->write_tmo,
> > +                                           msecs_to_jiffies(WRITE_TMO_MS));
> > +             else
> > +                     dev_err(udata->dev,
> > +                             "PPM unresponsive - too many write timeouts.");
> > +
> > +             return;
> > +     }
> > +
> > +     /* No longer busy means we can reset our timeout counter. */
> > +     udata->tmo_counter = 0;
> > +
> > +     /* Need to ack previous command which may have timed out. */
> > +     if (cci & UCSI_CCI_COMMAND_COMPLETE) {
> > +             cmd = UCSI_ACK_CC_CI | UCSI_ACK_COMMAND_COMPLETE;
> > +             cros_ucsi_async_control(udata->ucsi, &cmd);
> > +
> > +             /* Check again after a few seconds that the system has
> > +              * recovered to make sure our async write above was successful.
> > +              */
> > +             schedule_delayed_work(&udata->write_tmo,
> > +                                   msecs_to_jiffies(WRITE_TMO_MS));
> > +             return;
> > +     }
> > +
> > +     /* We recovered from a previous timeout. Treat this as a recovery from
> > +      * suspend and call resume.
> > +      */
> > +     ucsi_resume(udata->ucsi);
> > +}
> > +
> >  static int cros_ucsi_event(struct notifier_block *nb,
> >                          unsigned long host_event, void *_notify)
> >  {
> > @@ -162,6 +247,7 @@ static int cros_ucsi_probe(struct platform_device *pdev)
> >       platform_set_drvdata(pdev, udata);
> >
> >       INIT_WORK(&udata->work, cros_ucsi_work);
> > +     INIT_DELAYED_WORK(&udata->write_tmo, cros_ucsi_write_timeout);
> >       init_completion(&udata->complete);
> >
> >       udata->ucsi = ucsi_create(dev, &cros_ucsi_ops);
>
> thanks,
>
> --
> heikki