RE: [EXT] [PATCH v3 2/3] scsi: ufs-qcom: Implement device_reset vops

["Bean Huo (beanhuo)" <beanhuo@micron.com>]

Hi, Bjorn
This HW reset is dedicated to QUALCOMM based platform case.
how about adding a SW reset as to be default reset routine if platform doesn't support HW reset?

>-----Original Message-----
>From: linux-scsi-owner@vger.kernel.org <linux-scsi-owner@vger.kernel.org>
>On Behalf Of Bjorn Andersson
>Sent: Saturday, June 8, 2019 7:05 AM
>To: Rob Herring <robh+dt@kernel.org>; Mark Rutland
><mark.rutland@arm.com>; Alim Akhtar <alim.akhtar@samsung.com>; Avri
>Altman <avri.altman@wdc.com>; Pedro Sousa
><pedrom.sousa@synopsys.com>; James E.J. Bottomley <jejb@linux.ibm.com>;
>Martin K. Petersen <martin.petersen@oracle.com>
>Cc: Andy Gross <agross@kernel.org>; devicetree@vger.kernel.org; linux-
>kernel@vger.kernel.org; linux-arm-msm@vger.kernel.org; linux-
>scsi@vger.kernel.org
>Subject: [EXT] [PATCH v3 2/3] scsi: ufs-qcom: Implement device_reset vops
>
>The UFS_RESET pin on Qualcomm SoCs are controlled by TLMM and exposed
>through the GPIO framework. Acquire the device-reset GPIO and use this to
>implement the device_reset vops, to allow resetting the attached memory.
>
>Based on downstream support implemented by Subhash Jadavani
><subhashj@codeaurora.org>.
>
>Signed-off-by: Bjorn Andersson <bjorn.andersson@linaro.org>
>---
>
>Changes since v2:
>- Moved implementation to Qualcomm driver
>
> .../devicetree/bindings/ufs/ufshcd-pltfrm.txt |  2 ++
> drivers/scsi/ufs/ufs-qcom.c                   | 32 +++++++++++++++++++
> drivers/scsi/ufs/ufs-qcom.h                   |  4 +++
> 3 files changed, 38 insertions(+)
>
>diff --git a/Documentation/devicetree/bindings/ufs/ufshcd-pltfrm.txt
>b/Documentation/devicetree/bindings/ufs/ufshcd-pltfrm.txt
>index a74720486ee2..d562d8b4919c 100644
>--- a/Documentation/devicetree/bindings/ufs/ufshcd-pltfrm.txt
>+++ b/Documentation/devicetree/bindings/ufs/ufshcd-pltfrm.txt
>@@ -54,6 +54,8 @@ Optional properties:
> 			  PHY reset from the UFS controller.
> - resets            : reset node register
> - reset-names       : describe reset node register, the "rst" corresponds to
>reset the whole UFS IP.
>+- device-reset-gpios	: A phandle and gpio specifier denoting the GPIO
>connected
>+			  to the RESET pin of the UFS memory device.
>
> Note: If above properties are not defined it can be assumed that the supply
>regulators or clocks are always on.
>diff --git a/drivers/scsi/ufs/ufs-qcom.c b/drivers/scsi/ufs/ufs-qcom.c index
>ea7219407309..efaf57ba618a 100644
>--- a/drivers/scsi/ufs/ufs-qcom.c
>+++ b/drivers/scsi/ufs/ufs-qcom.c
>@@ -16,6 +16,7 @@
> #include <linux/of.h>
> #include <linux/platform_device.h>
> #include <linux/phy/phy.h>
>+#include <linux/gpio/consumer.h>
> #include <linux/reset-controller.h>
>
> #include "ufshcd.h"
>@@ -1141,6 +1142,15 @@ static int ufs_qcom_init(struct ufs_hba *hba)
> 		goto out_variant_clear;
> 	}
>
>+	host->device_reset = devm_gpiod_get_optional(dev, "device-reset",
>+						     GPIOD_OUT_HIGH);
>+	if (IS_ERR(host->device_reset)) {
>+		err = PTR_ERR(host->device_reset);
>+		if (err != -EPROBE_DEFER)
>+			dev_err(dev, "failed to acquire reset gpio: %d\n", err);
>+		goto out_variant_clear;
>+	}
>+
> 	err = ufs_qcom_bus_register(host);
> 	if (err)
> 		goto out_variant_clear;
>@@ -1546,6 +1556,27 @@ static void ufs_qcom_dump_dbg_regs(struct
>ufs_hba *hba)
> 	usleep_range(1000, 1100);
> }
>
>+/**
>+ * ufs_qcom_device_reset() - toggle the (optional) device reset line
>+ * @hba: per-adapter instance
>+ *
>+ * Toggles the (optional) reset line to reset the attached device.
>+ */
>+static void ufs_qcom_device_reset(struct ufs_hba *hba) {
>+	struct ufs_qcom_host *host = ufshcd_get_variant(hba);
>+
>+	/*
>+	 * The UFS device shall detect reset pulses of 1us, sleep for 10us to
>+	 * be on the safe side.
>+	 */
>+	gpiod_set_value_cansleep(host->device_reset, 1);
>+	usleep_range(10, 15);
>+
>+	gpiod_set_value_cansleep(host->device_reset, 0);
>+	usleep_range(10, 15);
>+}
>+
> /**
>  * struct ufs_hba_qcom_vops - UFS QCOM specific variant operations
>  *
>@@ -1566,6 +1597,7 @@ static struct ufs_hba_variant_ops
>ufs_hba_qcom_vops = {
> 	.suspend		= ufs_qcom_suspend,
> 	.resume			= ufs_qcom_resume,
> 	.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
>68a880185752..b96ffb6804e4 100644
>--- a/drivers/scsi/ufs/ufs-qcom.h
>+++ b/drivers/scsi/ufs/ufs-qcom.h
>@@ -204,6 +204,8 @@ struct ufs_qcom_testbus {
> 	u8 select_minor;
> };
>
>+struct gpio_desc;
>+
> struct ufs_qcom_host {
> 	/*
> 	 * Set this capability if host controller supports the QUniPro mode
>@@ -241,6 +243,8 @@ struct ufs_qcom_host {
> 	struct ufs_qcom_testbus testbus;
>
> 	struct reset_controller_dev rcdev;
>+
>+	struct gpio_desc *device_reset;
> };
>
> static inline u32
>--
>2.18.0