scsi: ufs: ufs-mediatek: Add host reset mechanism

Add host reset mechanism to try to recover host-side errors during recovery
flow.

Link: https://lore.kernel.org/r/20200908064507.30774-5-stanley.chu@mediatek.comSigned-off-by: Stanley Chu <stanley.chu@mediatek.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

drivers/scsi/ufs/ufs-mediatek.c

@@ -13,6 +13,7 @@
 #include <linux/phy/phy.h>
 #include <linux/platform_device.h>
 #include <linux/regulator/consumer.h>
+#include <linux/reset.h>
 #include <linux/soc/mediatek/mtk_sip_svc.h>
 
 #include "ufshcd.h"
@@ -91,16 +92,57 @@ static void ufs_mtk_crypto_enable(struct ufs_hba *hba)
 	}
 }
 
+static void ufs_mtk_host_reset(struct ufs_hba *hba)
+{
+	struct ufs_mtk_host *host = ufshcd_get_variant(hba);
+
+	reset_control_assert(host->hci_reset);
+	reset_control_assert(host->crypto_reset);
+	reset_control_assert(host->unipro_reset);
+
+	usleep_range(100, 110);
+
+	reset_control_deassert(host->unipro_reset);
+	reset_control_deassert(host->crypto_reset);
+	reset_control_deassert(host->hci_reset);
+}
+
+static void ufs_mtk_init_reset_control(struct ufs_hba *hba,
+				       struct reset_control **rc,
+				       char *str)
+{
+	*rc = devm_reset_control_get(hba->dev, str);
+	if (IS_ERR(*rc)) {
+		dev_info(hba->dev, "Failed to get reset control %s: %d\n",
+			 str, PTR_ERR(*rc));
+		*rc = NULL;
+	}
+}
+
+static void ufs_mtk_init_reset(struct ufs_hba *hba)
+{
+	struct ufs_mtk_host *host = ufshcd_get_variant(hba);
+
+	ufs_mtk_init_reset_control(hba, &host->hci_reset,
+				   "hci_rst");
+	ufs_mtk_init_reset_control(hba, &host->unipro_reset,
+				   "unipro_rst");
+	ufs_mtk_init_reset_control(hba, &host->crypto_reset,
+				   "crypto_rst");
+}
+
 static int ufs_mtk_hce_enable_notify(struct ufs_hba *hba,
 				     enum ufs_notify_change_status status)
 {
 	struct ufs_mtk_host *host = ufshcd_get_variant(hba);
 
 	if (status == PRE_CHANGE) {
-		if (host->unipro_lpm)
+		if (host->unipro_lpm) {
 			hba->vps->hba_enable_delay_us = 0;
-		else
+		} else {
 			hba->vps->hba_enable_delay_us = 600;
+			ufs_mtk_host_reset(hba);
+		}
 
 		if (hba->caps & UFSHCD_CAP_CRYPTO)
 			ufs_mtk_crypto_enable(hba);
@@ -335,6 +377,8 @@ static int ufs_mtk_init(struct ufs_hba *hba)
 	if (err)
 		goto out_variant_clear;
 
+	ufs_mtk_init_reset(hba);
+
 	/* Enable runtime autosuspend */
 	hba->caps |= UFSHCD_CAP_RPM_AUTOSUSPEND;
 

drivers/scsi/ufs/ufs-mediatek.h

@@ -92,6 +92,9 @@ enum {
 struct ufs_mtk_host {
 	struct ufs_hba *hba;
 	struct phy *mphy;
+	struct reset_control *hci_reset;
+	struct reset_control *unipro_reset;
+	struct reset_control *crypto_reset;
 	bool mphy_powered_on;
 	bool unipro_lpm;
 	bool ref_clk_enabled;