[PATCH 4/4] usb: typec: ucsi: ccg: add runtime pm workaround

[Ajay Gupta <ajaykuee@gmail.com>]

From: Ajay Gupta <ajayg@nvidia.com>

Cypress USB Type-C CCGx controller firmware verson 3.1.10
(which is being used in many NVIDIA GPU cards) has known issue of
not triggering interrupt when a USB device is hot plugged to runtime
resume the controller. Many of these cards may get latest kernel but
may not get latest fixed firmware so a workaround is required to
check for any connector change event.

The workaround is that i2c bus driver will call pm_request_resume()
to runtime resume ucsi_ccg driver. CCG driver will call the ISR
for any connector change event only if NVIDIA GPU has old
CCG firmware with the known issue.

Signed-off-by: Ajay Gupta <ajayg@nvidia.com>
---
 drivers/usb/typec/ucsi/ucsi_ccg.c | 78 +++++++++++++++++++++++++++++--
 1 file changed, 74 insertions(+), 4 deletions(-)

diff --git a/drivers/usb/typec/ucsi/ucsi_ccg.c b/drivers/usb/typec/ucsi/ucsi_ccg.c
index cc7094ecda2d..3457e112fdbc 100644
--- a/drivers/usb/typec/ucsi/ucsi_ccg.c
+++ b/drivers/usb/typec/ucsi/ucsi_ccg.c
@@ -109,6 +109,8 @@ struct version_format {
 	__le16 build;
 	u8 patch;
 	u8 ver;
+#define CCG_VERSION_PATCH(x) ((x) << 16)
+#define CCG_VERSION(x)	((x) << 24)
 #define CCG_VERSION_MIN_SHIFT (0)
 #define CCG_VERSION_MIN_MASK (0xf << CCG_VERSION_MIN_SHIFT)
 #define CCG_VERSION_MAJ_SHIFT (4)
@@ -172,6 +174,7 @@ struct ucsi_ccg {
 	struct ccg_dev_info info;
 	/* version info for boot, primary and secondary */
 	struct version_info version[FW2 + 1];
+	u32 fw_version;
 	/* CCG HPI communication flags */
 	unsigned long flags;
 #define RESET_PENDING	0
@@ -185,6 +188,10 @@ struct ucsi_ccg {
 
 	/* fw build with vendor information */
 	u16 fw_build;
+	bool run_isr; /* flag to call ISR routine during resume */
+	struct work_struct pm_work;
+	u16 old_fw_build;
+	u32 old_fw_version;
 };
 
 static int ccg_read(struct ucsi_ccg *uc, u16 rab, u8 *data, u32 len)
@@ -212,6 +219,17 @@ static int ccg_read(struct ucsi_ccg *uc, u16 rab, u8 *data, u32 len)
 	if (quirks && quirks->max_read_len)
 		max_read_len = quirks->max_read_len;
 
+	if (uc->old_fw_build == uc->fw_build &&
+	    uc->fw_version <= uc->old_fw_version) {
+		mutex_lock(&uc->lock);
+		/* do not schedule pm_work to run ISR in
+		 * ucsi_ccg_runtime_resume() after pm_runtime_get_sync()
+		 * since we are already in ISR path.
+		 */
+		uc->run_isr = false;
+		mutex_unlock(&uc->lock);
+	}
+
 	pm_runtime_get_sync(uc->dev);
 	while (rem_len > 0) {
 		msgs[1].buf = &data[len - rem_len];
@@ -254,6 +272,17 @@ static int ccg_write(struct ucsi_ccg *uc, u16 rab, u8 *data, u32 len)
 	msgs[0].len = len + sizeof(rab);
 	msgs[0].buf = buf;
 
+	if (uc->old_fw_build == uc->fw_build &&
+	    uc->fw_version <= uc->old_fw_version) {
+		mutex_lock(&uc->lock);
+		/* do not schedule pm_work to run ISR in
+		 * ucsi_ccg_runtime_resume() after pm_runtime_get_sync()
+		 * since we are already in ISR path.
+		 */
+		uc->run_isr = false;
+		mutex_unlock(&uc->lock);
+	}
+
 	pm_runtime_get_sync(uc->dev);
 	status = i2c_transfer(client->adapter, msgs, ARRAY_SIZE(msgs));
 	if (status < 0) {
@@ -383,6 +412,13 @@ static irqreturn_t ccg_irq_handler(int irq, void *data)
 	return IRQ_HANDLED;
 }
 
+static void ccg_pm_workaround_work(struct work_struct *pm_work)
+{
+	struct ucsi_ccg *uc = container_of(pm_work, struct ucsi_ccg, pm_work);
+
+	ucsi_notify(uc->ucsi);
+}
+
 static int get_fw_info(struct ucsi_ccg *uc)
 {
 	int err;
@@ -392,6 +428,9 @@ static int get_fw_info(struct ucsi_ccg *uc)
 	if (err < 0)
 		return err;
 
+	uc->fw_version = CCG_VERSION(uc->version[FW2].app.ver) |
+			CCG_VERSION_PATCH(uc->version[FW2].app.patch);
+
 	err = ccg_read(uc, CCGX_RAB_DEVICE_MODE, (u8 *)(&uc->info),
 		       sizeof(uc->info));
 	if (err < 0)
@@ -740,11 +779,12 @@ static bool ccg_check_fw_version(struct ucsi_ccg *uc, const char *fw_name,
 	}
 
 	/* compare input version with FWCT version */
-	cur_version = le16_to_cpu(app->build) | app->patch << 16 |
-			app->ver << 24;
+	cur_version = le16_to_cpu(app->build) | CCG_VERSION_PATCH(app->patch) |
+			CCG_VERSION(app->ver);
 
-	new_version = le16_to_cpu(fw_cfg.app.build) | fw_cfg.app.patch << 16 |
-			fw_cfg.app.ver << 24;
+	new_version = le16_to_cpu(fw_cfg.app.build) |
+			CCG_VERSION_PATCH(fw_cfg.app.patch) |
+			CCG_VERSION(fw_cfg.app.ver);
 
 	if (!ccg_check_vendor_version(uc, app, &fw_cfg))
 		goto out_release_firmware;
@@ -1084,8 +1124,16 @@ static int ucsi_ccg_probe(struct i2c_client *client,
 	uc->ppm.sync = ucsi_ccg_sync;
 	uc->dev = dev;
 	uc->client = client;
+	uc->run_isr = true;
 	mutex_init(&uc->lock);
 	INIT_WORK(&uc->work, ccg_update_firmware);
+	INIT_WORK(&uc->pm_work, ccg_pm_workaround_work);
+
+	/* Firmware version 3.1.10 or earlier, built for NVIDIA has known issue
+	 * of missing interrupt when a device is connected for runtime resume
+	 */
+	uc->old_fw_build = ('n' << 8) | 'v';
+	uc->old_fw_version = CCG_VERSION(0x31) | CCG_VERSION_PATCH(10);
 
 	/* Only fail FW flashing when FW build information is not provided */
 	status = device_property_read_u16(dev, "ccgx,firmware-build",
@@ -1153,6 +1201,7 @@ static int ucsi_ccg_remove(struct i2c_client *client)
 {
 	struct ucsi_ccg *uc = i2c_get_clientdata(client);
 
+	cancel_work_sync(&uc->pm_work);
 	cancel_work_sync(&uc->work);
 	ucsi_unregister_ppm(uc->ucsi);
 	pm_runtime_disable(uc->dev);
@@ -1198,6 +1247,27 @@ static int ucsi_ccg_runtime_suspend(struct device *dev)
 
 static int ucsi_ccg_runtime_resume(struct device *dev)
 {
+	struct i2c_client *client = to_i2c_client(dev);
+	struct ucsi_ccg *uc = i2c_get_clientdata(client);
+	bool schedule = true;
+
+	/* Firmware version "old_fw_version" or earlier, built for NVIDIA has
+	 * known issue of missing interrupt when a device is connected for
+	 * runtime resume. Schedule a work to call ISR as a workaround.
+	 */
+	if (uc->old_fw_build == uc->fw_build &&
+	    uc->fw_version <= uc->old_fw_version) {
+		mutex_lock(&uc->lock);
+		if (!uc->run_isr) {
+			uc->run_isr = true;
+			schedule = false;
+		}
+		mutex_unlock(&uc->lock);
+
+		if (schedule)
+			schedule_work(&uc->pm_work);
+	}
+
 	return 0;
 }
 
-- 
2.17.1