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Subject[PATCH v3 2/3] scsi: ufs-qcom: Implement device_reset vops
Date
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
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