scsi: ufs: Allow an error return value from ->device_reset()

It is simpler for drivers to provide a ->device_reset() callback
irrespective of whether the GPIO, or firmware interface necessary to do the
reset, is discovered during probe.

Change ->device_reset() to return an error code.  Drivers that provide the
callback, but do not do the reset operation should return -EOPNOTSUPP.

Link: https://lore.kernel.org/r/20201103141403.2142-3-adrian.hunter@intel.comReviewed-by: Asutosh Das <asutoshd@codeaurora.org>
Reviewed-by: Stanley Chu <stanley.chu@mediatek.com>
Reviewed-by: Bean huo <beanhuo@micron.com>
Reviewed-by: Can Guo <cang@codeaurora.org>
Signed-off-by: Adrian Hunter <adrian.hunter@intel.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

drivers/scsi/ufs/ufs-mediatek.c

@@ -743,7 +743,7 @@ static int ufs_mtk_link_startup_notify(struct ufs_hba *hba,
 	return ret;
 }
 
-static void ufs_mtk_device_reset(struct ufs_hba *hba)
+static int ufs_mtk_device_reset(struct ufs_hba *hba)
 {
 	struct arm_smccc_res res;
 
@@ -764,6 +764,8 @@ static void ufs_mtk_device_reset(struct ufs_hba *hba)
 	usleep_range(10000, 15000);
 
 	dev_info(hba->dev, "device reset done\n");
+
+	return 0;
 }
 
 static int ufs_mtk_link_set_hpm(struct ufs_hba *hba)

drivers/scsi/ufs/ufs-qcom.c

@@ -1422,13 +1422,13 @@ static void ufs_qcom_dump_dbg_regs(struct ufs_hba *hba)
  *
  * Toggles the (optional) reset line to reset the attached device.
  */
-static void ufs_qcom_device_reset(struct ufs_hba *hba)
+static int ufs_qcom_device_reset(struct ufs_hba *hba)
 {
 	struct ufs_qcom_host *host = ufshcd_get_variant(hba);
 
 	/* reset gpio is optional */
 	if (!host->device_reset)
-		return;
+		return -EOPNOTSUPP;
 
 	/*
 	 * The UFS device shall detect reset pulses of 1us, sleep for 10us to
@@ -1439,6 +1439,8 @@ static void ufs_qcom_device_reset(struct ufs_hba *hba)
 
 	gpiod_set_value_cansleep(host->device_reset, 0);
 	usleep_range(10, 15);
+
+	return 0;
 }
 
 #if IS_ENABLED(CONFIG_DEVFREQ_GOV_SIMPLE_ONDEMAND)

drivers/scsi/ufs/ufshcd.h

@@ -323,7 +323,7 @@ struct ufs_hba_variant_ops {
 	int     (*resume)(struct ufs_hba *, enum ufs_pm_op);
 	void	(*dbg_register_dump)(struct ufs_hba *hba);
 	int	(*phy_initialization)(struct ufs_hba *);
-	void	(*device_reset)(struct ufs_hba *hba);
+	int	(*device_reset)(struct ufs_hba *hba);
 	void	(*config_scaling_param)(struct ufs_hba *hba,
 					struct devfreq_dev_profile *profile,
 					void *data);
@@ -1207,9 +1207,12 @@ static inline void ufshcd_vops_dbg_register_dump(struct ufs_hba *hba)
 static inline void ufshcd_vops_device_reset(struct ufs_hba *hba)
 {
 	if (hba->vops && hba->vops->device_reset) {
-		hba->vops->device_reset(hba);
-		ufshcd_set_ufs_dev_active(hba);
-		ufshcd_update_reg_hist(&hba->ufs_stats.dev_reset, 0);
+		int err = hba->vops->device_reset(hba);
+
+		if (!err)
+			ufshcd_set_ufs_dev_active(hba);
+		if (err != -EOPNOTSUPP)
+			ufshcd_update_reg_hist(&hba->ufs_stats.dev_reset, err);
 	}
 }