scsi: ufs: ufs-mediatek: gate ref-clk during Auto-Hibern8

In current UFS driver design, hba->uic_link_state will not be changed after
link enters Hibern8 state by Auto-Hibern8 mechanism.  In this case,
reference clock gating will be skipped unless special handling is
implemented in vendor's callbacks.

Support reference clock gating during Auto-Hibern8 period in MediaTek
Chipsets: If link state is already in Hibern8 while Auto-Hibern8 feature is
enabled, gate reference clock in setup_clocks callback.

Link: https://lore.kernel.org/r/20200129105251.12466-5-stanley.chu@mediatek.com
Reviewed-by: Alim Akhtar <alim.akhtar@samsung.com>
Reviewed-by: Bean Huo <beanhuo@micron.com>
Signed-off-by: Stanley Chu <stanley.chu@mediatek.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

drivers/scsi/ufs/ufs-mediatek.c

@@ -143,6 +143,17 @@ out:
 	return 0;
 }
 
+static u32 ufs_mtk_link_get_state(struct ufs_hba *hba)
+{
+	u32 val;
+
+	ufshcd_writel(hba, 0x20, REG_UFS_DEBUG_SEL);
+	val = ufshcd_readl(hba, REG_UFS_PROBE);
+	val = val >> 28;
+
+	return val;
+}
+
 /**
  * ufs_mtk_setup_clocks - enables/disable clocks
  * @hba: host controller instance
@@ -155,7 +166,7 @@ static int ufs_mtk_setup_clocks(struct ufs_hba *hba, bool on,
 				enum ufs_notify_change_status status)
 {
 	struct ufs_mtk_host *host = ufshcd_get_variant(hba);
-	int ret = -EINVAL;
+	int ret = 0;
 
 	/*
 	 * In case ufs_mtk_init() is not yet done, simply ignore.
@@ -165,19 +176,24 @@ static int ufs_mtk_setup_clocks(struct ufs_hba *hba, bool on,
 	if (!host)
 		return 0;
 
-	switch (status) {
-	case PRE_CHANGE:
-		if (!on && !ufshcd_is_link_active(hba)) {
+	if (!on && status == PRE_CHANGE) {
+		if (!ufshcd_is_link_active(hba)) {
 			ufs_mtk_setup_ref_clk(hba, on);
 			ret = phy_power_off(host->mphy);
+		} else {
+			/*
+			 * Gate ref-clk if link state is in Hibern8
+			 * triggered by Auto-Hibern8.
+			 */
+			if (!ufshcd_can_hibern8_during_gating(hba) &&
+			    ufshcd_is_auto_hibern8_enabled(hba) &&
+			    ufs_mtk_link_get_state(hba) ==
+			    VS_LINK_HIBERN8)
+				ufs_mtk_setup_ref_clk(hba, on);
 		}
-		break;
-	case POST_CHANGE:
-		if (on) {
-			ret = phy_power_on(host->mphy);
-			ufs_mtk_setup_ref_clk(hba, on);
-		}
-		break;
+	} else if (on && status == POST_CHANGE) {
+		ret = phy_power_on(host->mphy);
+		ufs_mtk_setup_ref_clk(hba, on);
 	}
 
 	return ret;

drivers/scsi/ufs/ufs-mediatek.h

@@ -53,6 +53,18 @@
 #define VS_SAVEPOWERCONTROL         0xD0A6
 #define VS_UNIPROPOWERDOWNCONTROL   0xD0A8
 
+/*
+ * Vendor specific link state
+ */
+enum {
+	VS_LINK_DISABLED            = 0,
+	VS_LINK_DOWN                = 1,
+	VS_LINK_UP                  = 2,
+	VS_LINK_HIBERN8             = 3,
+	VS_LINK_LOST                = 4,
+	VS_LINK_CFG                 = 5,
+};
+
 /*
  * SiP commands
  */