[PATCH v2 0/2] mtd: spi-nor: Add flash device reset support

[PATCH v2 0/2] mtd: spi-nor: Add flash device reset support

[Sai Krishna Potthuri]

Update spi-nor dt-binding and spi-nor core to support flash device
reset using reset-gpios property.

changes in v2:
-> 1/2 - Updated the description of the 'reset-gpios' property.
-> 2/2 - Updated the reset sequence to match with "active low" flag in
device-tree, also removed unwanted comments.
-> 2/2 - Updated the logic to perform the flash reset unconditionally.
-> 2/2 - Updated the delay values to support more number of flash devices.

Sai Krishna Potthuri (2):
  dt-bindings: mtd: spi-nor: Add reset-gpios property
  mtd: spi-nor: Add support for flash reset

 .../bindings/mtd/jedec,spi-nor.yaml           |  6 +++++
 drivers/mtd/spi-nor/core.c                    | 25 +++++++++++++++++++
 2 files changed, 31 insertions(+)

-- 
2.17.1

[PATCH v2 1/2] dt-bindings: mtd: spi-nor: Add reset-gpios property

[Sai Krishna Potthuri]

SPI-NOR flashes have RESET pin which can be toggled using GPIO
controller, for those platforms reset-gpios property can be used to
reset the flash device.

Signed-off-by: Sai Krishna Potthuri <sai.krishna.potthuri@amd.com>
---
 Documentation/devicetree/bindings/mtd/jedec,spi-nor.yaml | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/Documentation/devicetree/bindings/mtd/jedec,spi-nor.yaml b/Documentation/devicetree/bindings/mtd/jedec,spi-nor.yaml
index 7149784a36ac..4e98f78be750 100644
--- a/Documentation/devicetree/bindings/mtd/jedec,spi-nor.yaml
+++ b/Documentation/devicetree/bindings/mtd/jedec,spi-nor.yaml
@@ -70,6 +70,12 @@ properties:
       be used on such systems, to denote the absence of a reliable reset
       mechanism.
 
+  reset-gpios:
+    description:
+      A GPIO line connected to the RESET (active low) signal of the device.
+      If "broken-flash-reset" is present then having this property does not
+      make any difference.
+
   partitions:
     type: object
 
-- 
2.17.1

Re: [PATCH v2 1/2] dt-bindings: mtd: spi-nor: Add reset-gpios property

[Krzysztof Kozlowski]

On 01/09/2022 10:29, Sai Krishna Potthuri wrote:
> SPI-NOR flashes have RESET pin which can be toggled using GPIO
> controller, for those platforms reset-gpios property can be used to
> reset the flash device.
> 
> Signed-off-by: Sai Krishna Potthuri <sai.krishna.potthuri@amd.com>
> ---

You still miss the user (DTS) of this change... The JEDEC spec did not
mention a reset pin. Can you provide the user?

Best regards,
Krzysztof

RE: [PATCH v2 1/2] dt-bindings: mtd: spi-nor: Add reset-gpios property

[Potthuri, Sai Krishna]

Hi Krzysztof,

> -----Original Message-----
> From: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
> Sent: Thursday, September 1, 2022 1:26 PM
> To: Potthuri, Sai Krishna <sai.krishna.potthuri@amd.com>; Tudor Ambarus
> <tudor.ambarus@microchip.com>; Pratyush Yadav <pratyush@kernel.org>;
> Michael Walle <michael@walle.cc>; Miquel Raynal
> <miquel.raynal@bootlin.com>; Richard Weinberger <richard@nod.at>;
> Vignesh Raghavendra <vigneshr@ti.com>; Rob Herring
> <robh+dt@kernel.org>; Krzysztof Kozlowski
> <krzysztof.kozlowski+dt@linaro.org>
> Cc: devicetree@vger.kernel.org; linux-mtd@lists.infradead.org; linux-
> kernel@vger.kernel.org; saikrishna12468@gmail.com; git (AMD-Xilinx)
> <git@amd.com>
> Subject: Re: [PATCH v2 1/2] dt-bindings: mtd: spi-nor: Add reset-gpios
> property
> 
> On 01/09/2022 10:29, Sai Krishna Potthuri wrote:
> > SPI-NOR flashes have RESET pin which can be toggled using GPIO
> > controller, for those platforms reset-gpios property can be used to
> > reset the flash device.
> >
> > Signed-off-by: Sai Krishna Potthuri <sai.krishna.potthuri@amd.com>
> > ---
> 
> You still miss the user (DTS) of this change...
Do you mean to have this property in example DTS in this yaml?

> The JEDEC spec did not mention
> a reset pin. Can you provide the user?
Xilinx Octal SPI (cdns,qspi-nor.yaml) is using this reset pin to reset the
flash device on Versal platform.
Do you want me to update the example dts in cdns,qspi-nor.yaml file
to reflect this property in this patch?

Regards
Sai Krishna

Re: [PATCH v2 1/2] dt-bindings: mtd: spi-nor: Add reset-gpios property

[Krzysztof Kozlowski]

On 01/09/2022 13:18, Potthuri, Sai Krishna wrote:
> Hi Krzysztof,
> 
>> -----Original Message-----
>> From: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
>> Sent: Thursday, September 1, 2022 1:26 PM
>> To: Potthuri, Sai Krishna <sai.krishna.potthuri@amd.com>; Tudor Ambarus
>> <tudor.ambarus@microchip.com>; Pratyush Yadav <pratyush@kernel.org>;
>> Michael Walle <michael@walle.cc>; Miquel Raynal
>> <miquel.raynal@bootlin.com>; Richard Weinberger <richard@nod.at>;
>> Vignesh Raghavendra <vigneshr@ti.com>; Rob Herring
>> <robh+dt@kernel.org>; Krzysztof Kozlowski
>> <krzysztof.kozlowski+dt@linaro.org>
>> Cc: devicetree@vger.kernel.org; linux-mtd@lists.infradead.org; linux-
>> kernel@vger.kernel.org; saikrishna12468@gmail.com; git (AMD-Xilinx)
>> <git@amd.com>
>> Subject: Re: [PATCH v2 1/2] dt-bindings: mtd: spi-nor: Add reset-gpios
>> property
>>
>> On 01/09/2022 10:29, Sai Krishna Potthuri wrote:
>>> SPI-NOR flashes have RESET pin which can be toggled using GPIO
>>> controller, for those platforms reset-gpios property can be used to
>>> reset the flash device.
>>>
>>> Signed-off-by: Sai Krishna Potthuri <sai.krishna.potthuri@amd.com>
>>> ---
>>
>> You still miss the user (DTS) of this change...
> Do you mean to have this property in example DTS in this yaml?

No, I want to see in-tree DTS using it.

> 
>> The JEDEC spec did not mention
>> a reset pin. Can you provide the user?
> Xilinx Octal SPI (cdns,qspi-nor.yaml) is using this reset pin to reset the
> flash device on Versal platform.> Do you want me to update the example dts in cdns,qspi-nor.yaml file
> to reflect this property in this patch?
> 


Best regards,
Krzysztof

RE: [PATCH v2 1/2] dt-bindings: mtd: spi-nor: Add reset-gpios property

[Potthuri, Sai Krishna]

Hi Krzysztof,

> -----Original Message-----
> From: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
> Sent: Thursday, September 1, 2022 3:58 PM
> To: Potthuri, Sai Krishna <sai.krishna.potthuri@amd.com>; Tudor Ambarus
> <tudor.ambarus@microchip.com>; Pratyush Yadav <pratyush@kernel.org>;
> Michael Walle <michael@walle.cc>; Miquel Raynal
> <miquel.raynal@bootlin.com>; Richard Weinberger <richard@nod.at>;
> Vignesh Raghavendra <vigneshr@ti.com>; Rob Herring
> <robh+dt@kernel.org>; Krzysztof Kozlowski
> <krzysztof.kozlowski+dt@linaro.org>
> Cc: devicetree@vger.kernel.org; linux-mtd@lists.infradead.org; linux-
> kernel@vger.kernel.org; saikrishna12468@gmail.com; git (AMD-Xilinx)
> <git@amd.com>
> Subject: Re: [PATCH v2 1/2] dt-bindings: mtd: spi-nor: Add reset-gpios
> property
> 
> On 01/09/2022 13:18, Potthuri, Sai Krishna wrote:
> > Hi Krzysztof,
> >
> >> -----Original Message-----
> >> From: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
> >> Sent: Thursday, September 1, 2022 1:26 PM
> >> To: Potthuri, Sai Krishna <sai.krishna.potthuri@amd.com>; Tudor
> >> Ambarus <tudor.ambarus@microchip.com>; Pratyush Yadav
> >> <pratyush@kernel.org>; Michael Walle <michael@walle.cc>; Miquel
> >> Raynal <miquel.raynal@bootlin.com>; Richard Weinberger
> >> <richard@nod.at>; Vignesh Raghavendra <vigneshr@ti.com>; Rob Herring
> >> <robh+dt@kernel.org>; Krzysztof Kozlowski
> >> <krzysztof.kozlowski+dt@linaro.org>
> >> Cc: devicetree@vger.kernel.org; linux-mtd@lists.infradead.org; linux-
> >> kernel@vger.kernel.org; saikrishna12468@gmail.com; git (AMD-Xilinx)
> >> <git@amd.com>
> >> Subject: Re: [PATCH v2 1/2] dt-bindings: mtd: spi-nor: Add
> >> reset-gpios property
> >>
> >> On 01/09/2022 10:29, Sai Krishna Potthuri wrote:
> >>> SPI-NOR flashes have RESET pin which can be toggled using GPIO
> >>> controller, for those platforms reset-gpios property can be used to
> >>> reset the flash device.
> >>>
> >>> Signed-off-by: Sai Krishna Potthuri <sai.krishna.potthuri@amd.com>
> >>> ---
> >>
> >> You still miss the user (DTS) of this change...
> > Do you mean to have this property in example DTS in this yaml?
> 
> No, I want to see in-tree DTS using it.
As Michal Simek talked to you about this over IRC, as of now we don’t have
a DTS in the mainline tree for Xilinx Versal platform but we have a plan to do it.
For time being i will add this property in the example dts in this yaml file.

Regards
Sai Krishna

Re: [PATCH v2 1/2] dt-bindings: mtd: spi-nor: Add reset-gpios property

[Krzysztof Kozlowski]

On 07/09/2022 11:49, Potthuri, Sai Krishna wrote:
>>>>>
>>>>> Signed-off-by: Sai Krishna Potthuri <sai.krishna.potthuri@amd.com>
>>>>> ---
>>>>
>>>> You still miss the user (DTS) of this change...
>>> Do you mean to have this property in example DTS in this yaml?
>>
>> No, I want to see in-tree DTS using it.
> As Michal Simek talked to you about this over IRC, as of now we don’t have
> a DTS in the mainline tree for Xilinx Versal platform but we have a plan to do it.
> For time being i will add this property in the example dts in this yaml file.

Sure, sounds good.


Best regards,
Krzysztof

[PATCH v2 2/2] mtd: spi-nor: Add support for flash reset

[Sai Krishna Potthuri]

Add support for spi-nor flash reset via GPIO controller by reading the
reset-gpio property. If there is a valid GPIO specifier then reset will
be performed by asserting and deasserting the GPIO using gpiod APIs
otherwise it will not perform any operation.

Signed-off-by: Sai Krishna Potthuri <sai.krishna.potthuri@amd.com>
---
 drivers/mtd/spi-nor/core.c | 25 +++++++++++++++++++++++++
 1 file changed, 25 insertions(+)

diff --git a/drivers/mtd/spi-nor/core.c b/drivers/mtd/spi-nor/core.c
index f2c64006f8d7..a78ab9bae2be 100644
--- a/drivers/mtd/spi-nor/core.c
+++ b/drivers/mtd/spi-nor/core.c
@@ -2933,6 +2933,27 @@ static void spi_nor_set_mtd_info(struct spi_nor *nor)
 	mtd->_put_device = spi_nor_put_device;
 }
 
+static int spi_nor_hw_reset(struct spi_nor *nor)
+{
+	struct gpio_desc *reset;
+
+	reset = devm_gpiod_get_optional(nor->dev, "reset", GPIOD_OUT_LOW);
+	if (IS_ERR_OR_NULL(reset))
+		return PTR_ERR_OR_ZERO(reset);
+
+	/*
+	 * Experimental delay values by looking at different flash device
+	 * vendors datasheets.
+	 */
+	usleep_range(1, 5);
+	gpiod_set_value_cansleep(reset, 1);
+	usleep_range(100, 150);
+	gpiod_set_value_cansleep(reset, 0);
+	usleep_range(1000, 1200);
+
+	return 0;
+}
+
 int spi_nor_scan(struct spi_nor *nor, const char *name,
 		 const struct spi_nor_hwcaps *hwcaps)
 {
@@ -2965,6 +2986,10 @@ int spi_nor_scan(struct spi_nor *nor, const char *name,
 	if (!nor->bouncebuf)
 		return -ENOMEM;
 
+	ret = spi_nor_hw_reset(nor);
+	if (ret)
+		return ret;
+
 	info = spi_nor_get_flash_info(nor, name);
 	if (IS_ERR(info))
 		return PTR_ERR(info);
-- 
2.17.1

Re: [PATCH v2 2/2] mtd: spi-nor: Add support for flash reset

[Michael Walle]

Am 2022-09-01 09:29, schrieb Sai Krishna Potthuri:
> Add support for spi-nor flash reset via GPIO controller by reading the
> reset-gpio property. If there is a valid GPIO specifier then reset will
> be performed by asserting and deasserting the GPIO using gpiod APIs
> otherwise it will not perform any operation.
> 
> Signed-off-by: Sai Krishna Potthuri <sai.krishna.potthuri@amd.com>

Reviewed-by: Michael Walle <michael@walle.cc>

Just one comment, see below

> ---
>  drivers/mtd/spi-nor/core.c | 25 +++++++++++++++++++++++++
>  1 file changed, 25 insertions(+)
> 
> diff --git a/drivers/mtd/spi-nor/core.c b/drivers/mtd/spi-nor/core.c
> index f2c64006f8d7..a78ab9bae2be 100644
> --- a/drivers/mtd/spi-nor/core.c
> +++ b/drivers/mtd/spi-nor/core.c
> @@ -2933,6 +2933,27 @@ static void spi_nor_set_mtd_info(struct spi_nor 
> *nor)
>  	mtd->_put_device = spi_nor_put_device;
>  }
> 
> +static int spi_nor_hw_reset(struct spi_nor *nor)
> +{
> +	struct gpio_desc *reset;
> +
> +	reset = devm_gpiod_get_optional(nor->dev, "reset", GPIOD_OUT_LOW);
> +	if (IS_ERR_OR_NULL(reset))
> +		return PTR_ERR_OR_ZERO(reset);
> +
> +	/*
> +	 * Experimental delay values by looking at different flash device
> +	 * vendors datasheets.
> +	 */
> +	usleep_range(1, 5);

I think this is superfluous, because parts of the kernel
will boot which should take longer than 1us. But I'm
fine with leaving it here.

-michael

> +	gpiod_set_value_cansleep(reset, 1);
> +	usleep_range(100, 150);
> +	gpiod_set_value_cansleep(reset, 0);
> +	usleep_range(1000, 1200);
> +
> +	return 0;
> +}
> +
>  int spi_nor_scan(struct spi_nor *nor, const char *name,
>  		 const struct spi_nor_hwcaps *hwcaps)
>  {
> @@ -2965,6 +2986,10 @@ int spi_nor_scan(struct spi_nor *nor, const char 
> *name,
>  	if (!nor->bouncebuf)
>  		return -ENOMEM;
> 
> +	ret = spi_nor_hw_reset(nor);
> +	if (ret)
> +		return ret;
> +
>  	info = spi_nor_get_flash_info(nor, name);
>  	if (IS_ERR(info))
>  		return PTR_ERR(info);