diff mbox series

[v2,1/4] reset: gpio: Add GPIO-based reset controller

Message ID 20240105155918.279657-2-krzysztof.kozlowski@linaro.org
State New
Headers
Series reset: gpio: ASoC: shared GPIO resets |

Commit Message

Krzysztof Kozlowski Jan. 5, 2024, 3:59 p.m. UTC 
  Add a simple driver to control GPIO-based resets using the reset
controller API for the cases when the GPIOs are shared and reset should
be coordinated.  The driver is expected to be used by reset core
framework for ad-hoc reset controllers.

Cc: Bartosz Golaszewski <brgl@bgdev.pl>
Cc: Sean Anderson <sean.anderson@seco.com>
Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
---
 MAINTAINERS                |   5 ++
 drivers/reset/Kconfig      |   9 +++
 drivers/reset/Makefile     |   1 +
 drivers/reset/reset-gpio.c | 121 +++++++++++++++++++++++++++++++++++++
 4 files changed, 136 insertions(+)
 create mode 100644 drivers/reset/reset-gpio.c

Comments

Biju Das Jan. 5, 2024, 4:39 p.m. UTC | #1 
Hi Krzysztof Kozlowski,

Thanks for the patch.

> -----Original Message-----
> From: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
> Sent: Friday, January 5, 2024 3:59 PM
> Subject: [PATCH v2 1/4] reset: gpio: Add GPIO-based reset controller
> 
> Add a simple driver to control GPIO-based resets using the reset
> controller API for the cases when the GPIOs are shared and reset should be
> coordinated.  The driver is expected to be used by reset core framework
> for ad-hoc reset controllers.
> 
> Cc: Bartosz Golaszewski <brgl@bgdev.pl>
> Cc: Sean Anderson <sean.anderson@seco.com>
> Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
> ---
>  MAINTAINERS                |   5 ++
>  drivers/reset/Kconfig      |   9 +++
>  drivers/reset/Makefile     |   1 +
>  drivers/reset/reset-gpio.c | 121 +++++++++++++++++++++++++++++++++++++
>  4 files changed, 136 insertions(+)
>  create mode 100644 drivers/reset/reset-gpio.c
> 
> diff --git a/MAINTAINERS b/MAINTAINERS
> index 7fe27cd60e1b..a0fbd4814bc7 100644
> --- a/MAINTAINERS
> +++ b/MAINTAINERS
> @@ -8866,6 +8866,11 @@ F:	Documentation/i2c/muxes/i2c-mux-gpio.rst
>  F:	drivers/i2c/muxes/i2c-mux-gpio.c
>  F:	include/linux/platform_data/i2c-mux-gpio.h
> 
> +GENERIC GPIO RESET DRIVER
> +M:	Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
> +S:	Maintained
> +F:	drivers/reset/reset-gpio.c
> +
>  GENERIC HDLC (WAN) DRIVERS
>  M:	Krzysztof Halasa <khc@pm.waw.pl>
>  S:	Maintained
> diff --git a/drivers/reset/Kconfig b/drivers/reset/Kconfig index
> ccd59ddd7610..bb1b5a326eb7 100644
> --- a/drivers/reset/Kconfig
> +++ b/drivers/reset/Kconfig
> @@ -66,6 +66,15 @@ config RESET_BRCMSTB_RESCAL
>  	  This enables the RESCAL reset controller for SATA, PCIe0, or PCIe1
> on
>  	  BCM7216.
> 
> +config RESET_GPIO
> +	tristate "GPIO reset controller"
> +	help
> +	  This enables a generic reset controller for resets attached via
> +	  GPIOs.  Typically for OF platforms this driver expects "reset-
> gpios"
> +	  property.
> +
> +	  If compiled as module, it will be called reset-gpio.
> +
>  config RESET_HSDK
>  	bool "Synopsys HSDK Reset Driver"
>  	depends on HAS_IOMEM
> diff --git a/drivers/reset/Makefile b/drivers/reset/Makefile index
> 8270da8a4baa..fd8b49fa46fc 100644
> --- a/drivers/reset/Makefile
> +++ b/drivers/reset/Makefile
> @@ -11,6 +11,7 @@ obj-$(CONFIG_RESET_BCM6345) += reset-bcm6345.o
>  obj-$(CONFIG_RESET_BERLIN) += reset-berlin.o
>  obj-$(CONFIG_RESET_BRCMSTB) += reset-brcmstb.o
>  obj-$(CONFIG_RESET_BRCMSTB_RESCAL) += reset-brcmstb-rescal.o
> +obj-$(CONFIG_RESET_GPIO) += reset-gpio.o
>  obj-$(CONFIG_RESET_HSDK) += reset-hsdk.o
>  obj-$(CONFIG_RESET_IMX7) += reset-imx7.o
>  obj-$(CONFIG_RESET_INTEL_GW) += reset-intel-gw.o diff --git
> a/drivers/reset/reset-gpio.c b/drivers/reset/reset-gpio.c new file mode
> 100644 index 000000000000..cf0a867cbc5f
> --- /dev/null
> +++ b/drivers/reset/reset-gpio.c
> @@ -0,0 +1,121 @@
> +// SPDX-License-Identifier: GPL-2.0
> +
> +#include <linux/gpio/consumer.h>
> +#include <linux/mod_devicetable.h>
> +#include <linux/module.h>
> +#include <linux/of.h>
> +#include <linux/platform_device.h>
> +#include <linux/reset-controller.h>
> +
> +struct reset_gpio_priv {
> +	struct reset_controller_dev rc;
> +	struct gpio_desc *reset;
> +};
> +
> +static inline struct reset_gpio_priv
> +*rc_to_reset_gpio(struct reset_controller_dev *rc) {
> +	return container_of(rc, struct reset_gpio_priv, rc); }
> +
> +static int reset_gpio_assert(struct reset_controller_dev *rc, unsigned
> +long id) {
> +	struct reset_gpio_priv *priv = rc_to_reset_gpio(rc);
> +
> +	gpiod_set_value_cansleep(priv->reset, 1);
> +
> +	return 0;
> +}
> +
> +static int reset_gpio_deassert(struct reset_controller_dev *rc,
> +			       unsigned long id)
> +{
> +	struct reset_gpio_priv *priv = rc_to_reset_gpio(rc);
> +
> +	gpiod_set_value_cansleep(priv->reset, 0);
> +
> +	return 0;
> +}
> +
> +static int reset_gpio_status(struct reset_controller_dev *rc, unsigned
> +long id) {
> +	struct reset_gpio_priv *priv = rc_to_reset_gpio(rc);
> +
> +	return gpiod_get_value_cansleep(priv->reset);
> +}
> +
> +static const struct reset_control_ops reset_gpio_ops = {
> +	.assert = reset_gpio_assert,
> +	.deassert = reset_gpio_deassert,
> +	.status = reset_gpio_status,
> +};
> +
> +static void reset_gpio_of_args_put(void *data) {
> +	of_node_put(data);
> +}
> +
> +static int reset_gpio_probe(struct platform_device *pdev) {
> +	struct device *dev = &pdev->dev;
> +	struct device_node **platdata = dev_get_platdata(dev);
> +	struct of_phandle_args gpio_args;
> +	struct reset_gpio_priv *priv;
> +	int ret;
> +
> +	if (!platdata || !*platdata)

Maybe, if (!(platdata && *platdata)) which reduces 1 inversion operation.

Cheers,
Biju
Krzysztof Kozlowski Jan. 6, 2024, 3:28 p.m. UTC | #2 
On 05/01/2024 17:39, Biju Das wrote:
> Hi Krzysztof Kozlowski,
> 
> Thanks for the patch.
> 
>> -----Original Message-----
>> From: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
>> Sent: Friday, January 5, 2024 3:59 PM
>> Subject: [PATCH v2 1/4] reset: gpio: Add GPIO-based reset controller
>>
>> Add a simple driver to control GPIO-based resets using the reset
>> controller API for the cases when the GPIOs are shared and reset should be
>> coordinated.  The driver is expected to be used by reset core framework
>> for ad-hoc reset controllers.
>>
>> Cc: Bartosz Golaszewski <brgl@bgdev.pl>
>> Cc: Sean Anderson <sean.anderson@seco.com>
>> Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
>> ---
>>  MAINTAINERS                |   5 ++
>>  drivers/reset/Kconfig      |   9 +++
>>  drivers/reset/Makefile     |   1 +
>>  drivers/reset/reset-gpio.c | 121 +++++++++++++++++++++++++++++++++++++
>>  4 files changed, 136 insertions(+)
>>  create mode 100644 drivers/reset/reset-gpio.c
>>
>> diff --git a/MAINTAINERS b/MAINTAINERS
>> index 7fe27cd60e1b..a0fbd4814bc7 100644
>> --- a/MAINTAINERS
>> +++ b/MAINTAINERS
>> @@ -8866,6 +8866,11 @@ F:	Documentation/i2c/muxes/i2c-mux-gpio.rst
>>  F:	drivers/i2c/muxes/i2c-mux-gpio.c
>>  F:	include/linux/platform_data/i2c-mux-gpio.h
>>
>> +GENERIC GPIO RESET DRIVER
>> +M:	Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
>> +S:	Maintained
>> +F:	drivers/reset/reset-gpio.c
>> +
>>  GENERIC HDLC (WAN) DRIVERS
>>  M:	Krzysztof Halasa <khc@pm.waw.pl>
>>  S:	Maintained
>> diff --git a/drivers/reset/Kconfig b/drivers/reset/Kconfig index
>> ccd59ddd7610..bb1b5a326eb7 100644
>> --- a/drivers/reset/Kconfig
>> +++ b/drivers/reset/Kconfig
>> @@ -66,6 +66,15 @@ config RESET_BRCMSTB_RESCAL
>>  	  This enables the RESCAL reset controller for SATA, PCIe0, or PCIe1
>> on
>>  	  BCM7216.
>>
>> +config RESET_GPIO
>> +	tristate "GPIO reset controller"
>> +	help
>> +	  This enables a generic reset controller for resets attached via
>> +	  GPIOs.  Typically for OF platforms this driver expects "reset-
>> gpios"
>> +	  property.
>> +
>> +	  If compiled as module, it will be called reset-gpio.
>> +
>>  config RESET_HSDK
>>  	bool "Synopsys HSDK Reset Driver"
>>  	depends on HAS_IOMEM
>> diff --git a/drivers/reset/Makefile b/drivers/reset/Makefile index
>> 8270da8a4baa..fd8b49fa46fc 100644
>> --- a/drivers/reset/Makefile
>> +++ b/drivers/reset/Makefile
>> @@ -11,6 +11,7 @@ obj-$(CONFIG_RESET_BCM6345) += reset-bcm6345.o
>>  obj-$(CONFIG_RESET_BERLIN) += reset-berlin.o
>>  obj-$(CONFIG_RESET_BRCMSTB) += reset-brcmstb.o
>>  obj-$(CONFIG_RESET_BRCMSTB_RESCAL) += reset-brcmstb-rescal.o
>> +obj-$(CONFIG_RESET_GPIO) += reset-gpio.o
>>  obj-$(CONFIG_RESET_HSDK) += reset-hsdk.o
>>  obj-$(CONFIG_RESET_IMX7) += reset-imx7.o
>>  obj-$(CONFIG_RESET_INTEL_GW) += reset-intel-gw.o diff --git
>> a/drivers/reset/reset-gpio.c b/drivers/reset/reset-gpio.c new file mode
>> 100644 index 000000000000..cf0a867cbc5f
>> --- /dev/null
>> +++ b/drivers/reset/reset-gpio.c
>> @@ -0,0 +1,121 @@
>> +// SPDX-License-Identifier: GPL-2.0
>> +
>> +#include <linux/gpio/consumer.h>
>> +#include <linux/mod_devicetable.h>
>> +#include <linux/module.h>
>> +#include <linux/of.h>
>> +#include <linux/platform_device.h>
>> +#include <linux/reset-controller.h>
>> +
>> +struct reset_gpio_priv {
>> +	struct reset_controller_dev rc;
>> +	struct gpio_desc *reset;
>> +};
>> +
>> +static inline struct reset_gpio_priv
>> +*rc_to_reset_gpio(struct reset_controller_dev *rc) {
>> +	return container_of(rc, struct reset_gpio_priv, rc); }
>> +
>> +static int reset_gpio_assert(struct reset_controller_dev *rc, unsigned
>> +long id) {
>> +	struct reset_gpio_priv *priv = rc_to_reset_gpio(rc);
>> +
>> +	gpiod_set_value_cansleep(priv->reset, 1);
>> +
>> +	return 0;
>> +}
>> +
>> +static int reset_gpio_deassert(struct reset_controller_dev *rc,
>> +			       unsigned long id)
>> +{
>> +	struct reset_gpio_priv *priv = rc_to_reset_gpio(rc);
>> +
>> +	gpiod_set_value_cansleep(priv->reset, 0);
>> +
>> +	return 0;
>> +}
>> +
>> +static int reset_gpio_status(struct reset_controller_dev *rc, unsigned
>> +long id) {
>> +	struct reset_gpio_priv *priv = rc_to_reset_gpio(rc);
>> +
>> +	return gpiod_get_value_cansleep(priv->reset);
>> +}
>> +
>> +static const struct reset_control_ops reset_gpio_ops = {
>> +	.assert = reset_gpio_assert,
>> +	.deassert = reset_gpio_deassert,
>> +	.status = reset_gpio_status,
>> +};
>> +
>> +static void reset_gpio_of_args_put(void *data) {
>> +	of_node_put(data);
>> +}
>> +
>> +static int reset_gpio_probe(struct platform_device *pdev) {
>> +	struct device *dev = &pdev->dev;
>> +	struct device_node **platdata = dev_get_platdata(dev);
>> +	struct of_phandle_args gpio_args;
>> +	struct reset_gpio_priv *priv;
>> +	int ret;
>> +
>> +	if (!platdata || !*platdata)
> 
> Maybe, if (!(platdata && *platdata)) which reduces 1 inversion operation.

I would not call it easier to understand... To me !A and !*A are quite
obvious and easy to read instantly because !A is obvious: check if it is
not NULL. Therefore original check is obvious: is NULL or points to
NULL? Then exit.

Now your check is a bit more complicated. It is not even frequent code
pattern which my brain used to see. You want to check if both are not
NULL and then negate it, wait, no, opposite, check if they are something
and then negate? To me it is really opposite of readable code.

Best regards,
Krzysztof
Biju Das Jan. 7, 2024, 10:46 a.m. UTC | #3 
Hi Krzysztof Kozlowski,

> -----Original Message-----
> From: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
> Sent: Saturday, January 6, 2024 3:29 PM
> Subject: Re: [PATCH v2 1/4] reset: gpio: Add GPIO-based reset controller
> 
> On 05/01/2024 17:39, Biju Das wrote:
> > Hi Krzysztof Kozlowski,
> >
> > Thanks for the patch.
> >
> >> -----Original Message-----
> >> From: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
> >> Sent: Friday, January 5, 2024 3:59 PM
> >> Subject: [PATCH v2 1/4] reset: gpio: Add GPIO-based reset controller
> >>
> >> Add a simple driver to control GPIO-based resets using the reset
> >> controller API for the cases when the GPIOs are shared and reset
> >> should be coordinated.  The driver is expected to be used by reset
> >> core framework for ad-hoc reset controllers.
> >>
> >> Cc: Bartosz Golaszewski <brgl@bgdev.pl>
> >> Cc: Sean Anderson <sean.anderson@seco.com>
> >> Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
> >> ---
> >>  MAINTAINERS                |   5 ++
> >>  drivers/reset/Kconfig      |   9 +++
> >>  drivers/reset/Makefile     |   1 +
> >>  drivers/reset/reset-gpio.c | 121
> >> +++++++++++++++++++++++++++++++++++++
> >>  4 files changed, 136 insertions(+)
> >>  create mode 100644 drivers/reset/reset-gpio.c
> >>
> >> diff --git a/MAINTAINERS b/MAINTAINERS index
> >> 7fe27cd60e1b..a0fbd4814bc7 100644
> >> --- a/MAINTAINERS
> >> +++ b/MAINTAINERS
> >> @@ -8866,6 +8866,11 @@ F:	Documentation/i2c/muxes/i2c-mux-gpio.rst
> >>  F:	drivers/i2c/muxes/i2c-mux-gpio.c
> >>  F:	include/linux/platform_data/i2c-mux-gpio.h
> >>
> >> +GENERIC GPIO RESET DRIVER
> >> +M:	Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
> >> +S:	Maintained
> >> +F:	drivers/reset/reset-gpio.c
> >> +
> >>  GENERIC HDLC (WAN) DRIVERS
> >>  M:	Krzysztof Halasa <khc@pm.waw.pl>
> >>  S:	Maintained
> >> diff --git a/drivers/reset/Kconfig b/drivers/reset/Kconfig index
> >> ccd59ddd7610..bb1b5a326eb7 100644
> >> --- a/drivers/reset/Kconfig
> >> +++ b/drivers/reset/Kconfig
> >> @@ -66,6 +66,15 @@ config RESET_BRCMSTB_RESCAL
> >>  	  This enables the RESCAL reset controller for SATA, PCIe0, or
> >> PCIe1 on
> >>  	  BCM7216.
> >>
> >> +config RESET_GPIO
> >> +	tristate "GPIO reset controller"
> >> +	help
> >> +	  This enables a generic reset controller for resets attached via
> >> +	  GPIOs.  Typically for OF platforms this driver expects "reset-
> >> gpios"
> >> +	  property.
> >> +
> >> +	  If compiled as module, it will be called reset-gpio.
> >> +
> >>  config RESET_HSDK
> >>  	bool "Synopsys HSDK Reset Driver"
> >>  	depends on HAS_IOMEM
> >> diff --git a/drivers/reset/Makefile b/drivers/reset/Makefile index
> >> 8270da8a4baa..fd8b49fa46fc 100644
> >> --- a/drivers/reset/Makefile
> >> +++ b/drivers/reset/Makefile
> >> @@ -11,6 +11,7 @@ obj-$(CONFIG_RESET_BCM6345) += reset-bcm6345.o
> >>  obj-$(CONFIG_RESET_BERLIN) += reset-berlin.o
> >>  obj-$(CONFIG_RESET_BRCMSTB) += reset-brcmstb.o
> >>  obj-$(CONFIG_RESET_BRCMSTB_RESCAL) += reset-brcmstb-rescal.o
> >> +obj-$(CONFIG_RESET_GPIO) += reset-gpio.o
> >>  obj-$(CONFIG_RESET_HSDK) += reset-hsdk.o
> >>  obj-$(CONFIG_RESET_IMX7) += reset-imx7.o
> >>  obj-$(CONFIG_RESET_INTEL_GW) += reset-intel-gw.o diff --git
> >> a/drivers/reset/reset-gpio.c b/drivers/reset/reset-gpio.c new file
> >> mode
> >> 100644 index 000000000000..cf0a867cbc5f
> >> --- /dev/null
> >> +++ b/drivers/reset/reset-gpio.c
> >> @@ -0,0 +1,121 @@
> >> +// SPDX-License-Identifier: GPL-2.0
> >> +
> >> +#include <linux/gpio/consumer.h>
> >> +#include <linux/mod_devicetable.h>
> >> +#include <linux/module.h>
> >> +#include <linux/of.h>
> >> +#include <linux/platform_device.h>
> >> +#include <linux/reset-controller.h>
> >> +
> >> +struct reset_gpio_priv {
> >> +	struct reset_controller_dev rc;
> >> +	struct gpio_desc *reset;
> >> +};
> >> +
> >> +static inline struct reset_gpio_priv *rc_to_reset_gpio(struct
> >> +reset_controller_dev *rc) {
> >> +	return container_of(rc, struct reset_gpio_priv, rc); }
> >> +
> >> +static int reset_gpio_assert(struct reset_controller_dev *rc,
> >> +unsigned long id) {
> >> +	struct reset_gpio_priv *priv = rc_to_reset_gpio(rc);
> >> +
> >> +	gpiod_set_value_cansleep(priv->reset, 1);
> >> +
> >> +	return 0;
> >> +}
> >> +
> >> +static int reset_gpio_deassert(struct reset_controller_dev *rc,
> >> +			       unsigned long id)
> >> +{
> >> +	struct reset_gpio_priv *priv = rc_to_reset_gpio(rc);
> >> +
> >> +	gpiod_set_value_cansleep(priv->reset, 0);
> >> +
> >> +	return 0;
> >> +}
> >> +
> >> +static int reset_gpio_status(struct reset_controller_dev *rc,
> >> +unsigned long id) {
> >> +	struct reset_gpio_priv *priv = rc_to_reset_gpio(rc);
> >> +
> >> +	return gpiod_get_value_cansleep(priv->reset);
> >> +}
> >> +
> >> +static const struct reset_control_ops reset_gpio_ops = {
> >> +	.assert = reset_gpio_assert,
> >> +	.deassert = reset_gpio_deassert,
> >> +	.status = reset_gpio_status,
> >> +};
> >> +
> >> +static void reset_gpio_of_args_put(void *data) {
> >> +	of_node_put(data);
> >> +}
> >> +
> >> +static int reset_gpio_probe(struct platform_device *pdev) {
> >> +	struct device *dev = &pdev->dev;
> >> +	struct device_node **platdata = dev_get_platdata(dev);
> >> +	struct of_phandle_args gpio_args;
> >> +	struct reset_gpio_priv *priv;
> >> +	int ret;
> >> +
> >> +	if (!platdata || !*platdata)
> >
> > Maybe, if (!(platdata && *platdata)) which reduces 1 inversion
> operation.
> 
> I would not call it easier to understand... To me !A and !*A are quite
> obvious and easy to read instantly because !A is obvious: check if it is
> not NULL. Therefore original check is obvious: is NULL or points to NULL?
> Then exit.
> 
> Now your check is a bit more complicated. It is not even frequent code
> pattern which my brain used to see. You want to check if both are not NULL
> and then negate it, wait, no, opposite, check if they are something and
> then negate? To me it is really opposite of readable code.

I agree maybe it is not readable, even though it reduces 1 extra operation.

!(Valid pointer AND points to a non NULL value)
Then exit.

Cheers,
Biju
Krzysztof Kozlowski Jan. 7, 2024, 11:56 a.m. UTC | #4 
On 07/01/2024 11:46, Biju Das wrote:
>>>> +
>>>> +	if (!platdata || !*platdata)
>>>
>>> Maybe, if (!(platdata && *platdata)) which reduces 1 inversion
>> operation.
>>
>> I would not call it easier to understand... To me !A and !*A are quite
>> obvious and easy to read instantly because !A is obvious: check if it is
>> not NULL. Therefore original check is obvious: is NULL or points to NULL?
>> Then exit.
>>
>> Now your check is a bit more complicated. It is not even frequent code
>> pattern which my brain used to see. You want to check if both are not NULL
>> and then negate it, wait, no, opposite, check if they are something and
>> then negate? To me it is really opposite of readable code.
> 
> I agree maybe it is not readable, even though it reduces 1 extra operation.
> 

Number of operations does not matter. Code readability matters.
Compilers are nowadays smarter than us, so don't write code more
difficult to read just to optimize some instruction like this.

Best regards,
Krzysztof
Philipp Zabel Jan. 8, 2024, 12:21 p.m. UTC | #5 
On Fr, 2024-01-05 at 16:59 +0100, Krzysztof Kozlowski wrote:
> Add a simple driver to control GPIO-based resets using the reset
> controller API for the cases when the GPIOs are shared and reset should
> be coordinated.  The driver is expected to be used by reset core
> framework for ad-hoc reset controllers.

I don't know how evil it is to set a parent-less platform device's
of_node to another device's node, but I like the simplicity of a
single-GPIO reset controller driver more that I had expected.

[...]
> diff --git a/drivers/reset/reset-gpio.c b/drivers/reset/reset-gpio.c
> new file mode 100644
> index 000000000000..cf0a867cbc5f
> --- /dev/null
> +++ b/drivers/reset/reset-gpio.c
> @@ -0,0 +1,121 @@
[...]
> +static void reset_gpio_of_args_put(void *data)

This should probably be called reset_gpio_of_node_put().

> +{
> +	of_node_put(data);
> +}
[...]

regards
Philipp
Krzysztof Kozlowski Jan. 9, 2024, 11 a.m. UTC | #6 
On 08/01/2024 13:21, Philipp Zabel wrote:
> On Fr, 2024-01-05 at 16:59 +0100, Krzysztof Kozlowski wrote:
>> Add a simple driver to control GPIO-based resets using the reset
>> controller API for the cases when the GPIOs are shared and reset should
>> be coordinated.  The driver is expected to be used by reset core
>> framework for ad-hoc reset controllers.
> 
> I don't know how evil it is to set a parent-less platform device's
> of_node to another device's node, but I like the simplicity of a
> single-GPIO reset controller driver more that I had expected.
> 
> [...]
>> diff --git a/drivers/reset/reset-gpio.c b/drivers/reset/reset-gpio.c
>> new file mode 100644
>> index 000000000000..cf0a867cbc5f
>> --- /dev/null
>> +++ b/drivers/reset/reset-gpio.c
>> @@ -0,0 +1,121 @@
> [...]
>> +static void reset_gpio_of_args_put(void *data)
> 
> This should probably be called reset_gpio_of_node_put().

Ack

Best regards,
Krzysztof
diff mbox series

Patch

diff --git a/MAINTAINERS b/MAINTAINERS
index 7fe27cd60e1b..a0fbd4814bc7 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -8866,6 +8866,11 @@  F:	Documentation/i2c/muxes/i2c-mux-gpio.rst
 F:	drivers/i2c/muxes/i2c-mux-gpio.c
 F:	include/linux/platform_data/i2c-mux-gpio.h
 
+GENERIC GPIO RESET DRIVER
+M:	Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
+S:	Maintained
+F:	drivers/reset/reset-gpio.c
+
 GENERIC HDLC (WAN) DRIVERS
 M:	Krzysztof Halasa <khc@pm.waw.pl>
 S:	Maintained
diff --git a/drivers/reset/Kconfig b/drivers/reset/Kconfig
index ccd59ddd7610..bb1b5a326eb7 100644
--- a/drivers/reset/Kconfig
+++ b/drivers/reset/Kconfig
@@ -66,6 +66,15 @@  config RESET_BRCMSTB_RESCAL
 	  This enables the RESCAL reset controller for SATA, PCIe0, or PCIe1 on
 	  BCM7216.
 
+config RESET_GPIO
+	tristate "GPIO reset controller"
+	help
+	  This enables a generic reset controller for resets attached via
+	  GPIOs.  Typically for OF platforms this driver expects "reset-gpios"
+	  property.
+
+	  If compiled as module, it will be called reset-gpio.
+
 config RESET_HSDK
 	bool "Synopsys HSDK Reset Driver"
 	depends on HAS_IOMEM
diff --git a/drivers/reset/Makefile b/drivers/reset/Makefile
index 8270da8a4baa..fd8b49fa46fc 100644
--- a/drivers/reset/Makefile
+++ b/drivers/reset/Makefile
@@ -11,6 +11,7 @@  obj-$(CONFIG_RESET_BCM6345) += reset-bcm6345.o
 obj-$(CONFIG_RESET_BERLIN) += reset-berlin.o
 obj-$(CONFIG_RESET_BRCMSTB) += reset-brcmstb.o
 obj-$(CONFIG_RESET_BRCMSTB_RESCAL) += reset-brcmstb-rescal.o
+obj-$(CONFIG_RESET_GPIO) += reset-gpio.o
 obj-$(CONFIG_RESET_HSDK) += reset-hsdk.o
 obj-$(CONFIG_RESET_IMX7) += reset-imx7.o
 obj-$(CONFIG_RESET_INTEL_GW) += reset-intel-gw.o
diff --git a/drivers/reset/reset-gpio.c b/drivers/reset/reset-gpio.c
new file mode 100644
index 000000000000..cf0a867cbc5f
--- /dev/null
+++ b/drivers/reset/reset-gpio.c
@@ -0,0 +1,121 @@ 
+// SPDX-License-Identifier: GPL-2.0
+
+#include <linux/gpio/consumer.h>
+#include <linux/mod_devicetable.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/platform_device.h>
+#include <linux/reset-controller.h>
+
+struct reset_gpio_priv {
+	struct reset_controller_dev rc;
+	struct gpio_desc *reset;
+};
+
+static inline struct reset_gpio_priv
+*rc_to_reset_gpio(struct reset_controller_dev *rc)
+{
+	return container_of(rc, struct reset_gpio_priv, rc);
+}
+
+static int reset_gpio_assert(struct reset_controller_dev *rc, unsigned long id)
+{
+	struct reset_gpio_priv *priv = rc_to_reset_gpio(rc);
+
+	gpiod_set_value_cansleep(priv->reset, 1);
+
+	return 0;
+}
+
+static int reset_gpio_deassert(struct reset_controller_dev *rc,
+			       unsigned long id)
+{
+	struct reset_gpio_priv *priv = rc_to_reset_gpio(rc);
+
+	gpiod_set_value_cansleep(priv->reset, 0);
+
+	return 0;
+}
+
+static int reset_gpio_status(struct reset_controller_dev *rc, unsigned long id)
+{
+	struct reset_gpio_priv *priv = rc_to_reset_gpio(rc);
+
+	return gpiod_get_value_cansleep(priv->reset);
+}
+
+static const struct reset_control_ops reset_gpio_ops = {
+	.assert = reset_gpio_assert,
+	.deassert = reset_gpio_deassert,
+	.status = reset_gpio_status,
+};
+
+static void reset_gpio_of_args_put(void *data)
+{
+	of_node_put(data);
+}
+
+static int reset_gpio_probe(struct platform_device *pdev)
+{
+	struct device *dev = &pdev->dev;
+	struct device_node **platdata = dev_get_platdata(dev);
+	struct of_phandle_args gpio_args;
+	struct reset_gpio_priv *priv;
+	int ret;
+
+	if (!platdata || !*platdata)
+		return -EINVAL;
+
+	priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL);
+	if (!priv)
+		return -ENOMEM;
+
+	platform_set_drvdata(pdev, &priv->rc);
+	device_set_node(dev, of_fwnode_handle(*platdata));
+
+	priv->reset = devm_gpiod_get(dev, "reset", GPIOD_OUT_HIGH);
+	if (IS_ERR(priv->reset))
+		return dev_err_probe(dev, PTR_ERR(priv->reset),
+				     "Could not get reset gpios\n");
+
+	ret = of_parse_phandle_with_args(*platdata, "reset-gpios",
+					 "#gpio-cells", 0, &gpio_args);
+	if (ret)
+		return ret;
+
+	priv->rc.ops = &reset_gpio_ops;
+	priv->rc.owner = THIS_MODULE;
+	priv->rc.dev = dev;
+	priv->rc.nr_resets = 1;
+	priv->rc.of_node = gpio_args.np;
+	ret = devm_add_action_or_reset(dev, reset_gpio_of_args_put,
+				       priv->rc.of_node);
+	if (ret)
+		return ret;
+
+	priv->rc.of_args = devm_kmemdup(dev, &gpio_args, sizeof(gpio_args),
+					GFP_KERNEL);
+	if (!priv->rc.of_args)
+		return -ENOMEM;
+
+	return devm_reset_controller_register(dev, &priv->rc);
+}
+
+static const struct platform_device_id reset_gpio_ids[] = {
+	{ .name = "reset-gpio", },
+	{}
+};
+MODULE_DEVICE_TABLE(platform, reset_gpio_ids);
+
+static struct platform_driver reset_gpio_driver = {
+	.probe		= reset_gpio_probe,
+	.id_table	= reset_gpio_ids,
+	.driver	= {
+		.name = "reset-gpio",
+	},
+};
+module_platform_driver(reset_gpio_driver);
+
+MODULE_AUTHOR("Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>");
+MODULE_DESCRIPTION("Generic GPIO reset driver");
+MODULE_LICENSE("GPL");