[PATCH v2 2/2] scsi: ufs-mediatek: add device reset implementation

[Stanley Chu <stanley.chu@xxxxxxxxxxxx>]

Add device reset vops implementation in MediaTek UFS driver.

Signed-off-by: Stanley Chu <stanley.chu@xxxxxxxxxxxx>
---
 drivers/scsi/ufs/ufs-mediatek.c | 27 +++++++++++++++++++++++++++
 drivers/scsi/ufs/ufs-mediatek.h |  7 +++++++
 2 files changed, 34 insertions(+)

diff --git a/drivers/scsi/ufs/ufs-mediatek.c b/drivers/scsi/ufs/ufs-mediatek.c
index 83e28edc3ac5..6a3ec11b16db 100644
--- a/drivers/scsi/ufs/ufs-mediatek.c
+++ b/drivers/scsi/ufs/ufs-mediatek.c
@@ -6,10 +6,12 @@
  *	Peter Wang <peter.wang@xxxxxxxxxxxx>
  */
 
+#include <linux/arm-smccc.h>
 #include <linux/of.h>
 #include <linux/of_address.h>
 #include <linux/phy/phy.h>
 #include <linux/platform_device.h>
+#include <linux/soc/mediatek/mtk_sip_svc.h>
 
 #include "ufshcd.h"
 #include "ufshcd-pltfrm.h"
@@ -269,6 +271,30 @@ static int ufs_mtk_link_startup_notify(struct ufs_hba *hba,
 	return ret;
 }
 
+static void ufs_mtk_device_reset(struct ufs_hba *hba)
+{
+	struct arm_smccc_res res;
+
+	arm_smccc_smc(MTK_SIP_UFS_CONTROL, UFS_MTK_SIP_DEVICE_RESET,
+		      0, 0, 0, 0, 0, 0, &res);
+	/*
+	 * The reset signal is active low. UFS devices shall detect
+	 * more than or equal to 1us of positive or negative RST_n
+	 * pulse width.
+	 *
+	 * To be on safe side, keep the reset low for at least 10us.
+	 */
+	usleep_range(10, 15);
+
+	arm_smccc_smc(MTK_SIP_UFS_CONTROL, UFS_MTK_SIP_DEVICE_RESET,
+		      1, 0, 0, 0, 0, 0, &res);
+
+	/* Some devices may need time to respond to rst_n */
+	usleep_range(10000, 15000);
+
+	dev_info(hba->dev, "device reset done\n");
+}
+
 static int ufs_mtk_suspend(struct ufs_hba *hba, enum ufs_pm_op pm_op)
 {
 	struct ufs_mtk_host *host = ufshcd_get_variant(hba);
@@ -303,6 +329,7 @@ static struct ufs_hba_variant_ops ufs_hba_mtk_vops = {
 	.pwr_change_notify   = ufs_mtk_pwr_change_notify,
 	.suspend             = ufs_mtk_suspend,
 	.resume              = ufs_mtk_resume,
+	.device_reset        = ufs_mtk_device_reset,
 };
 
 /**
diff --git a/drivers/scsi/ufs/ufs-mediatek.h b/drivers/scsi/ufs/ufs-mediatek.h
index 19f8c42fe06f..b03f601d3a9e 100644
--- a/drivers/scsi/ufs/ufs-mediatek.h
+++ b/drivers/scsi/ufs/ufs-mediatek.h
@@ -6,6 +6,8 @@
 #ifndef _UFS_MEDIATEK_H
 #define _UFS_MEDIATEK_H
 
+#include <linux/bitops.h>
+
 /*
  * Vendor specific pre-defined parameters
  */
@@ -29,6 +31,11 @@
 #define VS_SAVEPOWERCONTROL         0xD0A6
 #define VS_UNIPROPOWERDOWNCONTROL   0xD0A8
 
+/*
+ * SiP commands
+ */
+#define UFS_MTK_SIP_DEVICE_RESET    BIT(1)
+
 /*
  * VS_DEBUGCLOCKENABLE
  */
-- 
2.18.0