[PATCH v4 2/7] scsi: ufs-qcom: Add reset control support for host controller

[PATCH v4 2/7] scsi: ufs-qcom: Add reset control support for host controller

[Can Guo]

Add reset control for host controller so that host controller can be reset
as required in its power up sequence.

Signed-off-by: Can Guo <cang@codeaurora.org>
---
 drivers/scsi/ufs/ufs-qcom.c | 53 +++++++++++++++++++++++++++++++++++++++++++++
 drivers/scsi/ufs/ufs-qcom.h |  3 +++
 2 files changed, 56 insertions(+)

diff --git a/drivers/scsi/ufs/ufs-qcom.c b/drivers/scsi/ufs/ufs-qcom.c
index a5b7148..c69c29a1c 100644
--- a/drivers/scsi/ufs/ufs-qcom.c
+++ b/drivers/scsi/ufs/ufs-qcom.c
@@ -246,6 +246,44 @@ static void ufs_qcom_select_unipro_mode(struct ufs_qcom_host *host)
 	mb();
 }
 
+/**
+ * ufs_qcom_host_reset - reset host controller and PHY
+ */
+static int ufs_qcom_host_reset(struct ufs_hba *hba)
+{
+	int ret = 0;
+	struct ufs_qcom_host *host = ufshcd_get_variant(hba);
+
+	if (!host->core_reset) {
+		dev_warn(hba->dev, "%s: reset control not set\n", __func__);
+		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);
+
+	usleep_range(1000, 1100);
+
+out:
+	return ret;
+}
+
 static int ufs_qcom_power_up_sequence(struct ufs_hba *hba)
 {
 	struct ufs_qcom_host *host = ufshcd_get_variant(hba);
@@ -254,6 +292,12 @@ static int ufs_qcom_power_up_sequence(struct ufs_hba *hba)
 	bool is_rate_B = (UFS_QCOM_LIMIT_HS_RATE == PA_HS_MODE_B)
 							? true : false;
 
+	/* Reset UFS Host Controller and PHY */
+	ret = ufs_qcom_host_reset(hba);
+	if (ret)
+		dev_warn(hba->dev, "%s: host reset returned %d\n",
+				  __func__, ret);
+
 	if (is_rate_B)
 		phy_set_mode(phy, PHY_MODE_UFS_HS_B);
 
@@ -1101,6 +1145,15 @@ 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;
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;
-- 
The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum,
a Linux Foundation Collaborative Project

RE: [PATCH v4 2/7] scsi: ufs-qcom: Add reset control support for host controller

[Avri Altman]

Hi,

> 
> 
> Add reset control for host controller so that host controller can be reset as
> required in its power up sequence.
> 
> Signed-off-by: Can Guo <cang@codeaurora.org>
> +       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);
Aren't you sleeping anyway in your reset_control_ops?

> +
> +       ret = reset_control_deassert(host->core_reset);
> +       if (ret)
> +               dev_err(hba->dev, "%s: core_reset deassert failed, err = %d\n",
> +                                __func__, ret);
> +
> +       usleep_range(1000, 1100);
ditto

Re: [PATCH v4 2/7] scsi: ufs-qcom: Add reset control support for host controller

[Can Guo]

On 2019-11-14 17:03, Avri Altman wrote:
> Hi,
> 
>> 
>> 
>> Add reset control for host controller so that host controller can be 
>> reset as
>> required in its power up sequence.
>> 
>> Signed-off-by: Can Guo <cang@codeaurora.org>
>> +       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);
> Aren't you sleeping anyway in your reset_control_ops?
> 

For our cases, reset_control_assert uses the reset_control_ops->assert() 
we registered for
node &clock_gcc. There is no sleep or delay in Q's 
reset_control_ops->assert() func.

>> +
>> +       ret = reset_control_deassert(host->core_reset);
>> +       if (ret)
>> +               dev_err(hba->dev, "%s: core_reset deassert failed, err 
>> = %d\n",
>> +                                __func__, ret);
>> +
>> +       usleep_range(1000, 1100);
> ditto

Same as above.

Best Regards,
Can Guo.