linux-kernel - [PATCH v1 2/2] scsi: ufs-qcom: Add reset control support for host controller

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Date:   Tue, 22 Oct 2019 21:13:28 -0700
From:   Can Guo <cang@...eaurora.org>
To:     asutoshd@...eaurora.org, nguyenb@...eaurora.org,
        rnayak@...eaurora.org, linux-scsi@...r.kernel.org,
        kernel-team@...roid.com, saravanak@...gle.com, salyzyn@...gle.com,
        cang@...eaurora.org
Cc:     Andy Gross <agross@...nel.org>,
        Alim Akhtar <alim.akhtar@...sung.com>,
        Avri Altman <avri.altman@....com>,
        Pedro Sousa <pedrom.sousa@...opsys.com>,
        "James E.J. Bottomley" <jejb@...ux.ibm.com>,
        "Martin K. Petersen" <martin.petersen@...cle.com>,
        linux-arm-msm@...r.kernel.org (open list:ARM/QUALCOMM SUPPORT),
        linux-kernel@...r.kernel.org (open list)
Subject: [PATCH v1 2/2] scsi: ufs-qcom: Add reset control support for host controller

Add reset control for host controller and provide it through vops to UFS
core driver.

Signed-off-by: Can Guo <cang@...eaurora.org>
---
 drivers/scsi/ufs/ufs-qcom.c | 43 +++++++++++++++++++++++++++++++++++++++++++
 drivers/scsi/ufs/ufs-qcom.h |  3 +++
 2 files changed, 46 insertions(+)

diff --git a/drivers/scsi/ufs/ufs-qcom.c b/drivers/scsi/ufs/ufs-qcom.c
index a5b7148..3dee906 100644
--- a/drivers/scsi/ufs/ufs-qcom.c
+++ b/drivers/scsi/ufs/ufs-qcom.c
@@ -576,6 +576,39 @@ static int ufs_qcom_resume(struct ufs_hba *hba, enum ufs_pm_op pm_op)
 	return 0;
 }
 
+static int ufs_qcom_full_reset(struct ufs_hba *hba)
+{
+	int ret = -ENOTSUPP;
+	struct ufs_qcom_host *host = ufshcd_get_variant(hba);
+
+	if (!host->core_reset) {
+		dev_warn(hba->dev, "%s: failed, err = %d\n", __func__, ret);
+		goto out;
+	}
+
+	ret = reset_control_assert(host->core_reset);
+	if (ret) {
+		dev_err(hba->dev, "%s: core_reset assert failed, err = %d\n",
+				 __func__, ret);
+		goto out;
+	}
+
+	/*
+	 * The hardware requirement for delay between assert/deassert
+	 * is at least 3-4 sleep clock (32.7KHz) cycles, which comes to
+	 * ~125us (4/32768). To be on the safe side add 200us delay.
+	 */
+	usleep_range(200, 210);
+
+	ret = reset_control_deassert(host->core_reset);
+	if (ret)
+		dev_err(hba->dev, "%s: core_reset deassert failed, err = %d\n",
+				 __func__, ret);
+
+out:
+	return ret;
+}
+
 #ifdef CONFIG_MSM_BUS_SCALING
 static int ufs_qcom_get_bus_vote(struct ufs_qcom_host *host,
 		const char *speed_mode)
@@ -1101,6 +1134,15 @@ static int ufs_qcom_init(struct ufs_hba *hba)
 	host->hba = hba;
 	ufshcd_set_variant(hba, host);
 
+	/* Setup the reset control of HCI */
+	host->core_reset = devm_reset_control_get(hba->dev, "rst");
+	if (IS_ERR(host->core_reset)) {
+		err = PTR_ERR(host->core_reset);
+		dev_warn(dev, "Failed to get reset control %d\n", err);
+		host->core_reset = NULL;
+		err = 0;
+	}
+
 	/* Fire up the reset controller. Failure here is non-fatal. */
 	host->rcdev.of_node = dev->of_node;
 	host->rcdev.ops = &ufs_qcom_reset_ops;
@@ -1596,6 +1638,7 @@ static void ufs_qcom_device_reset(struct ufs_hba *hba)
 	.apply_dev_quirks	= ufs_qcom_apply_dev_quirks,
 	.suspend		= ufs_qcom_suspend,
 	.resume			= ufs_qcom_resume,
+	.full_reset		= ufs_qcom_full_reset,
 	.dbg_register_dump	= ufs_qcom_dump_dbg_regs,
 	.device_reset		= ufs_qcom_device_reset,
 };
diff --git a/drivers/scsi/ufs/ufs-qcom.h b/drivers/scsi/ufs/ufs-qcom.h
index d401f17..2d95e7c 100644
--- a/drivers/scsi/ufs/ufs-qcom.h
+++ b/drivers/scsi/ufs/ufs-qcom.h
@@ -6,6 +6,7 @@
 #define UFS_QCOM_H_
 
 #include <linux/reset-controller.h>
+#include <linux/reset.h>
 
 #define MAX_UFS_QCOM_HOSTS	1
 #define MAX_U32                 (~(u32)0)
@@ -233,6 +234,8 @@ struct ufs_qcom_host {
 	u32 dbg_print_en;
 	struct ufs_qcom_testbus testbus;
 
+	/* Reset control of HCI */
+	struct reset_control *core_reset;
 	struct reset_controller_dev rcdev;
 
 	struct gpio_desc *device_reset;
-- 
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