Re: GPIO bindings guidelines (Was: Re: [PATCH v5 10/12] gpio: Support for unified device properties interface)

["Rafael J. Wysocki" <rjw@rjwysocki.net>]

On Friday, October 24, 2014 10:34:36 AM Mika Westerberg wrote:
> On Thu, Oct 23, 2014 at 11:51:59PM +0200, Rafael J. Wysocki wrote:
> > OK, let's try to take that a bit farther. :-)
> > 
> > With the (untested) patch below applied (which is a replacement for the one
> > sent previously), the driver can use static tables like these:
> > 
> > static struct acpi_gpio_params reset_gpios = { 0, 0, false };
> > statuc struct acpi_gpio_params shutdown_gpios = { 1, 0, false };
> > 
> > static struct acpi_gpio_mapping my_gpio_mapping[] = {
> > 	{ "reset-gpios", &reset_gpios, 1 },
> > 	{ "shutdown-gpios", &shutdown_gpios, 1 },
> > 	NULL,
> > };
> > 
> 
> This is even better :-)
> 
> I tried this with few changes:
> 
>  - constify the mapping parameter
>  - check for NULL adev->driver_gpios in acpi_get_driver_gpio_data()
>  - check for gm->name instead of gm in acpi_get_driver_gpio_data()
> 
> It works just fine. For reference here are my changes to rkill-gpio.c:
> 
> diff --git a/net/rfkill/rfkill-gpio.c b/net/rfkill/rfkill-gpio.c
> index 0f62326c0f5e..ec8f5ac53520 100644
> --- a/net/rfkill/rfkill-gpio.c
> +++ b/net/rfkill/rfkill-gpio.c
> @@ -63,6 +63,15 @@ static const struct rfkill_ops rfkill_gpio_ops = {
>  	.set_block = rfkill_gpio_set_power,
>  };
>  
> +static const struct acpi_gpio_params reset_gpios = { 0, 0, false };
> +static const struct acpi_gpio_params shutdown_gpios = { 1, 0, false };
> +
> +static const struct acpi_gpio_mapping acpi_rfkill_default_gpios[] = {
> +	{ "reset-gpios", &reset_gpios, 1 },
> +	{ "shutdown-gpios", &shutdown_gpios, 1 },
> +	{ },
> +};
> +
>  static int rfkill_gpio_acpi_probe(struct device *dev,
>  				  struct rfkill_gpio_data *rfkill)
>  {
> @@ -75,7 +84,8 @@ static int rfkill_gpio_acpi_probe(struct device *dev,
>  	rfkill->name = dev_name(dev);
>  	rfkill->type = (unsigned)id->driver_data;
>  
> -	return 0;
> +	return acpi_dev_add_driver_gpios(ACPI_COMPANION(dev),
> +					 acpi_rfkill_default_gpios);
>  }
>  
>  static int rfkill_gpio_probe(struct platform_device *pdev)
> @@ -110,7 +120,7 @@ static int rfkill_gpio_probe(struct platform_device *pdev)
>  		rfkill->reset_gpio = gpio;
>  	}
>  
> -	gpio = devm_gpiod_get_index(&pdev->dev, "shutdown", 1);
> +	gpio = devm_gpiod_get_index(&pdev->dev, "shutdown", 0);
>  	if (!IS_ERR(gpio)) {
>  		ret = gpiod_direction_output(gpio, 0);
>  		if (ret)
> @@ -150,6 +160,8 @@ static int rfkill_gpio_remove(struct platform_device *pdev)
>  	rfkill_unregister(rfkill->rfkill_dev);
>  	rfkill_destroy(rfkill->rfkill_dev);
>  
> +	acpi_dev_remove_driver_gpios(ACPI_COMPANION(&pdev->dev));
> +
>  	return 0;
>  }
>  
> And here are the changes on top of your patch:
> 
> diff --git a/drivers/gpio/gpiolib-acpi.c b/drivers/gpio/gpiolib-acpi.c
> index 691501b53c5e..4151cd774f2f 100644
> --- a/drivers/gpio/gpiolib-acpi.c
> +++ b/drivers/gpio/gpiolib-acpi.c
> @@ -288,7 +288,7 @@ void acpi_gpiochip_free_interrupts(struct gpio_chip *chip)
>  }
>  
>  int acpi_dev_add_driver_gpios(struct acpi_device *adev,
> -			      struct acpi_gpio_mapping *gpios)
> +			      const struct acpi_gpio_mapping *gpios)
>  {
>  	if (adev && gpios) {
>  		adev->driver_gpios = gpios;
> @@ -302,11 +302,14 @@ static bool acpi_get_driver_gpio_data(struct acpi_device *adev,
>  				      const char *name, int index,
>  				      struct acpi_reference_args *args)
>  {
> -	struct acpi_gpio_mapping *gm;
> +	const struct acpi_gpio_mapping *gm;
>  
> -	for (gm = adev->driver_gpios; gm; gm++)
> +	if (!adev->driver_gpios)
> +		return false;
> +
> +	for (gm = adev->driver_gpios; gm->name; gm++)
>  		if (!strcmp(name, gm->name) && gm->data && index < gm->size) {
> -			struct acpi_gpio_params *par = gm->data + index;
> +			const struct acpi_gpio_params *par = gm->data + index;
>  
>  			args->adev = adev;
>  			args->args[0] = par->crs_entry_index;
> diff --git a/include/acpi/acpi_bus.h b/include/acpi/acpi_bus.h
> index 2de7a2614c61..98d992062270 100644
> --- a/include/acpi/acpi_bus.h
> +++ b/include/acpi/acpi_bus.h
> @@ -368,7 +368,7 @@ struct acpi_device {
>  	struct acpi_scan_handler *handler;
>  	struct acpi_hotplug_context *hp;
>  	struct acpi_driver *driver;
> -	struct acpi_gpio_mapping *driver_gpios;
> +	const struct acpi_gpio_mapping *driver_gpios;
>  	void *driver_data;
>  	struct device dev;
>  	unsigned int physical_node_count;
> diff --git a/include/linux/acpi.h b/include/linux/acpi.h
> index 26b7a639f4b9..23f9c55d0331 100644
> --- a/include/linux/acpi.h
> +++ b/include/linux/acpi.h
> @@ -680,13 +680,13 @@ struct acpi_gpio_params {
>  
>  struct acpi_gpio_mapping {
>  	const char *name;
> -	struct acpi_gpio_params *data;
> +	const struct acpi_gpio_params *data;
>  	unsigned int size;
>  };
>  
>  #if defined(CONFIG_ACPI) && defined(CONFIG_GPIOLIB)
>  int acpi_dev_add_driver_gpios(struct acpi_device *adev,
> -			      struct acpi_gpio_mapping *gpios);
> +			      const struct acpi_gpio_mapping *gpios);
>  
>  static inline void acpi_dev_remove_driver_gpios(struct acpi_device *adev)
>  {
> @@ -695,7 +695,7 @@ static inline void acpi_dev_remove_driver_gpios(struct acpi_device *adev)
>  }
>  #else
>  static inline int acpi_dev_add_driver_gpios(struct acpi_device *adev,
> -			      struct acpi_gpio_mapping *gpios)
> +			      const struct acpi_gpio_mapping *gpios)
>  {
>  	return -ENXIO;
>  }

Thanks!

I folded your fixes into my patch and I'm going to send the result, with a
changelog, in a reply to this message.

If everyone is happy with it, I'll add it to the device properties patch
series as it depends on those.

I guess you can add a changelog to your rfkill changes and then we could
add them to that series too if there are no objections.


-- 
I speak only for myself.
Rafael J. Wysocki, Intel Open Source Technology Center.