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

[Biju Das]

Hi Krzysztof Kozlowski,

Thanks for the patch.

> -----Original Message-----
> From: Krzysztof Kozlowski <krzysztof.kozlowski@xxxxxxxxxx>
> 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@xxxxxxxx>
> Cc: Sean Anderson <sean.anderson@xxxxxxxx>
> Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@xxxxxxxxxx>
> ---
>  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@xxxxxxxxxx>
> +S:	Maintained
> +F:	drivers/reset/reset-gpio.c
> +
>  GENERIC HDLC (WAN) DRIVERS
>  M:	Krzysztof Halasa <khc@xxxxxxxxx>
>  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