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Subject[PATCH v2 2/3] scsi: ufs: Allow resetting the UFS device
Date
Acquire the device-reset GPIO and toggle this to reset the UFS device
during initialization and host reset.

Based on downstream support implemented by Subhash Jadavani
<subhashj@codeaurora.org>.

Tested-by: John Stultz <john.stultz@linaro.org>
Signed-off-by: Bjorn Andersson <bjorn.andersson@linaro.org>
---

Changes since v1:
- Added gpio to DT binding document
- Fixed spelling of UFS

.../devicetree/bindings/ufs/ufshcd-pltfrm.txt | 2 +
drivers/scsi/ufs/ufshcd.c | 44 +++++++++++++++++++
drivers/scsi/ufs/ufshcd.h | 4 ++
3 files changed, 50 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/ufshcd.c b/drivers/scsi/ufs/ufshcd.c
index a208589426b1..eaa384d67684 100644
--- a/drivers/scsi/ufs/ufshcd.c
+++ b/drivers/scsi/ufs/ufshcd.c
@@ -42,6 +42,7 @@
#include <linux/nls.h>
#include <linux/of.h>
#include <linux/bitfield.h>
+#include <linux/gpio/consumer.h>
#include "ufshcd.h"
#include "ufs_quirks.h"
#include "unipro.h"
@@ -6135,6 +6136,25 @@ static int ufshcd_abort(struct scsi_cmnd *cmd)
return err;
}

+/**
+ * ufshcd_device_reset() - toggle the (optional) device reset line
+ * @hba: per-adapter instance
+ *
+ * Toggles the (optional) reset line to reset the attached device.
+ */
+static void ufshcd_device_reset(struct ufs_hba *hba)
+{
+ /*
+ * The UFS device shall detect reset pulses of 1us, sleep for 10us to
+ * be on the safe side.
+ */
+ gpiod_set_value_cansleep(hba->device_reset, 1);
+ usleep_range(10, 15);
+
+ gpiod_set_value_cansleep(hba->device_reset, 0);
+ usleep_range(10, 15);
+}
+
/**
* ufshcd_host_reset_and_restore - reset and restore host controller
* @hba: per-adapter instance
@@ -6190,6 +6210,9 @@ static int ufshcd_reset_and_restore(struct ufs_hba *hba)
int retries = MAX_HOST_RESET_RETRIES;

do {
+ /* Reset the attached device */
+ ufshcd_device_reset(hba);
+
err = ufshcd_host_reset_and_restore(hba);
} while (err && --retries);

@@ -7386,6 +7409,18 @@ static void ufshcd_variant_hba_exit(struct ufs_hba *hba)
ufshcd_vops_exit(hba);
}

+static int ufshcd_init_device_reset(struct ufs_hba *hba)
+{
+ hba->device_reset = devm_gpiod_get_optional(hba->dev, "device-reset",
+ GPIOD_OUT_HIGH);
+ if (IS_ERR(hba->device_reset)) {
+ dev_err(hba->dev, "failed to acquire reset gpio: %ld\n",
+ PTR_ERR(hba->device_reset));
+ }
+
+ return PTR_ERR_OR_ZERO(hba->device_reset);
+}
+
static int ufshcd_hba_init(struct ufs_hba *hba)
{
int err;
@@ -7425,9 +7460,15 @@ static int ufshcd_hba_init(struct ufs_hba *hba)
if (err)
goto out_disable_vreg;

+ err = ufshcd_init_device_reset(hba);
+ if (err)
+ goto out_disable_variant;
+
hba->is_powered = true;
goto out;

+out_disable_variant:
+ ufshcd_vops_setup_regulators(hba, false);
out_disable_vreg:
ufshcd_setup_vreg(hba, false);
out_disable_clks:
@@ -8321,6 +8362,9 @@ int ufshcd_init(struct ufs_hba *hba, void __iomem *mmio_base, unsigned int irq)
goto exit_gating;
}

+ /* Reset the attached device */
+ ufshcd_device_reset(hba);
+
/* Host controller enable */
err = ufshcd_hba_enable(hba);
if (err) {
diff --git a/drivers/scsi/ufs/ufshcd.h b/drivers/scsi/ufs/ufshcd.h
index 994d73d03207..4443928ba7d2 100644
--- a/drivers/scsi/ufs/ufshcd.h
+++ b/drivers/scsi/ufs/ufshcd.h
@@ -72,6 +72,8 @@
#define UFSHCD "ufshcd"
#define UFSHCD_DRIVER_VERSION "0.2"

+struct gpio_desc;
+
struct ufs_hba;

enum dev_cmd_type {
@@ -706,6 +708,8 @@ struct ufs_hba {

struct device bsg_dev;
struct request_queue *bsg_queue;
+
+ struct gpio_desc *device_reset;
};

/* Returns true if clocks can be gated. Otherwise false */
--
2.18.0
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