scsi: ufs: ufs-mediatek: Support low-power mode for VCCQ

Allow VCCQ to enter low-power mode, and also remove the restriction of VCC
because VCCQ/VCCQ2 can be changed to low-power mode even if VCC stays on
while the device is not in active power mode.

Link: https://lore.kernel.org/r/20220616053725.5681-7-stanley.chu@mediatek.comReviewed-by: Stanley Chu <stanley.chu@mediatek.com>
Signed-off-by: Peter Wang <peter.wang@mediatek.com>
Signed-off-by: Stanley Chu <stanley.chu@mediatek.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

drivers/ufs/host/ufs-mediatek.c

@@ -1031,7 +1031,13 @@ static int ufs_mtk_link_set_lpm(struct ufs_hba *hba)
 
 static void ufs_mtk_vreg_set_lpm(struct ufs_hba *hba, bool lpm)
 {
-	if (!hba->vreg_info.vccq2 || !hba->vreg_info.vcc)
+	struct ufs_vreg *vccqx = NULL;
+
+	if (!hba->vreg_info.vccq && !hba->vreg_info.vccq2)
+		return;
+
+	/* Skip if VCC is assumed always-on */
+	if (!hba->vreg_info.vcc)
 		return;
 
 	/* Bypass LPM when device is still active */
@@ -1042,12 +1048,13 @@ static void ufs_mtk_vreg_set_lpm(struct ufs_hba *hba, bool lpm)
 	if (lpm && hba->vreg_info.vcc->enabled)
 		return;
 
-	if (lpm)
-		regulator_set_mode(hba->vreg_info.vccq2->reg,
-				   REGULATOR_MODE_IDLE);
+	if (hba->vreg_info.vccq)
+		vccqx = hba->vreg_info.vccq;
 	else
-		regulator_set_mode(hba->vreg_info.vccq2->reg,
-				   REGULATOR_MODE_NORMAL);
+		vccqx = hba->vreg_info.vccq2;
+
+	regulator_set_mode(vccqx->reg,
+			   lpm ? REGULATOR_MODE_IDLE : REGULATOR_MODE_NORMAL);
 }
 
 static void ufs_mtk_auto_hibern8_disable(struct ufs_hba *hba)