diff mbox series

[v2,2/3] scsi: ufs: Allow resetting the UFS device

Message ID 20190606010249.3538-3-bjorn.andersson@linaro.org (mailing list archive)
State Superseded
Headers show
Series (Qualcomm) UFS device reset support | expand

Commit Message

Bjorn Andersson June 6, 2019, 1:02 a.m. UTC
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(+)

Comments

Avri Altman June 6, 2019, 6:36 a.m. UTC | #1
>  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);
Is this necessary?
ufshcd_vops_setup_regulators() was just called as part of ufshcd_variant_hba_init

Thanks,
Avri
Bjorn Andersson June 6, 2019, 7:18 a.m. UTC | #2
On Wed 05 Jun 23:36 PDT 2019, Avri Altman wrote:

> 
> >  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);
> Is this necessary?
> ufshcd_vops_setup_regulators() was just called as part of ufshcd_variant_hba_init
> 

Yes, so my attempt here is to reverse the enablement of the vops
regulators (hence passing false). But looking at it again I see that we
should also do ufshcd_vops_exit(), so the right thing to call here is
ufshcd_variant_hba_exit().

PS. This initialization sequence should really be rewritten to first
acquire all resources and then turn them on. This mixes init/setup
sequence is really hard to reason about.

Regards,
Bjorn
Rob Herring (Arm) July 9, 2019, 1:48 a.m. UTC | #3
On Wed, Jun 05, 2019 at 06:02:48PM -0700, Bjorn Andersson wrote:
> 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.

A sign we should have a child node for the device...

Doesn't using 'reset-gpios' work as I doubt one would have a GPIO reset 
for the host controller.

Rob
Linus Walleij July 28, 2019, 10:09 p.m. UTC | #4
On Thu, Jun 6, 2019 at 3:02 AM Bjorn Andersson
<bjorn.andersson@linaro.org> wrote:

> 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>

I agree with Rob that just "reset-gpios" looks better.
Otherwise:
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>

Yours,
Linus Walleij
diff mbox series

Patch

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 */