linux-kernel - Re: [PATCH 4/5] gpio: of: Add support to have multiple gpios in gpio-hog

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Message-ID: <20160309062849.GB10454@pengutronix.de>
Date:	Wed, 9 Mar 2016 07:28:49 +0100
From:	Markus Pargmann <mpa@...gutronix.de>
To:	Laxman Dewangan <ldewangan@...dia.com>
Cc:	linus.walleij@...aro.org, robh+dt@...nel.org, pawel.moll@....com,
	mark.rutland@....com, devicetree@...r.kernel.org,
	linux-kernel@...r.kernel.org, linux-gpio@...r.kernel.org,
	treding@...dia.com, swarren@...dotorg.org,
	Benoit Parrot <bparrot@...com>,
	Alexandre Courbot <acourbot@...dia.com>
Subject: Re: [PATCH 4/5] gpio: of: Add support to have multiple gpios in
 gpio-hog

Hi,

On Tue, Mar 08, 2016 at 05:32:07PM +0530, Laxman Dewangan wrote:
> The child node for gpio hogs under gpio controller's node
> provide the mechanism to automatic GPIO request and
> configuration as part of the gpio-controller's driver
> probe function.
> 
> Currently, property "gpio" takes one gpios for such
> configuration. Add support to have multiple GPIOs in
> this property so that multiple GPIOs of gpio-controller
> can be configured by this mechanism with one child node.

So if I read this correctly you want to have multiple GPIOs with the
same line name? Why don't you use multiple child nodes with individual
line names?

Best Regards,

Markus

> 
> Signed-off-by: Laxman Dewangan <ldewangan@...dia.com>
> Cc: Benoit Parrot <bparrot@...com>
> Cc: Alexandre Courbot <acourbot@...dia.com>
> ---
>  drivers/gpio/gpiolib-of.c | 64 ++++++++++++++++++++++++++++++++++++-----------
>  1 file changed, 49 insertions(+), 15 deletions(-)
> 
> diff --git a/drivers/gpio/gpiolib-of.c b/drivers/gpio/gpiolib-of.c
> index d81dbd8..0e4e8fd 100644
> --- a/drivers/gpio/gpiolib-of.c
> +++ b/drivers/gpio/gpiolib-of.c
> @@ -118,6 +118,21 @@ int of_get_named_gpio_flags(struct device_node *np, const char *list_name,
>  }
>  EXPORT_SYMBOL(of_get_named_gpio_flags);
>  
> +static int of_gpio_get_gpio_cells_size(struct device_node *chip_np)
> +{
> +	u32 ncells;
> +	int ret;
> +
> +	ret = of_property_read_u32(chip_np, "#gpio-cells", &ncells);
> +	if (ret)
> +		return ret;
> +
> +	if (ncells > MAX_PHANDLE_ARGS)
> +		return -EINVAL;
> +
> +	return ncells;
> +}
> +
>  /**
>   * of_parse_own_gpio() - Get a GPIO hog descriptor, names and flags for GPIO API
>   * @np:		device node to get GPIO from
> @@ -131,6 +146,7 @@ EXPORT_SYMBOL(of_get_named_gpio_flags);
>   */
>  static struct gpio_desc *of_parse_own_gpio(struct device_node *np,
>  					   const char **name,
> +					   int gpio_index,
>  					   enum gpio_lookup_flags *lflags,
>  					   enum gpiod_flags *dflags)
>  {
> @@ -139,8 +155,8 @@ static struct gpio_desc *of_parse_own_gpio(struct device_node *np,
>  	struct gg_data gg_data = {
>  		.flags = &xlate_flags,
>  	};
> -	u32 tmp;
> -	int i, ret;
> +	int ncells;
> +	int i, start_index, ret;
>  
>  	chip_np = np->parent;
>  	if (!chip_np)
> @@ -150,17 +166,16 @@ static struct gpio_desc *of_parse_own_gpio(struct device_node *np,
>  	*lflags = 0;
>  	*dflags = 0;
>  
> -	ret = of_property_read_u32(chip_np, "#gpio-cells", &tmp);
> -	if (ret)
> -		return ERR_PTR(ret);
> +	ncells = of_gpio_get_gpio_cells_size(chip_np);
> +	if (ncells < 0)
> +		return ERR_PTR(ncells);
>  
> -	if (tmp > MAX_PHANDLE_ARGS)
> -		return ERR_PTR(-EINVAL);
> +	start_index = ncells * gpio_index;
>  
> -	gg_data.gpiospec.args_count = tmp;
> +	gg_data.gpiospec.args_count = ncells;
>  	gg_data.gpiospec.np = chip_np;
> -	for (i = 0; i < tmp; i++) {
> -		ret = of_property_read_u32_index(np, "gpios", i,
> +	for (i = 0; i < ncells; i++) {
> +		ret = of_property_read_u32_index(np, "gpios", start_index + i,
>  					   &gg_data.gpiospec.args[i]);
>  		if (ret)
>  			return ERR_PTR(ret);
> @@ -211,18 +226,37 @@ static int of_gpiochip_scan_gpios(struct gpio_chip *chip)
>  	enum gpio_lookup_flags lflags;
>  	enum gpiod_flags dflags;
>  	int ret;
> +	int i, ncells, ngpios;
> +
> +	ncells = of_gpio_get_gpio_cells_size(chip->of_node);
> +	if (ncells < 0)
> +		return 0;
>  
>  	for_each_available_child_of_node(chip->of_node, np) {
>  		if (!of_property_read_bool(np, "gpio-hog"))
>  			continue;
>  
> -		desc = of_parse_own_gpio(np, &name, &lflags, &dflags);
> -		if (IS_ERR(desc))
> +		ngpios = of_property_count_u32_elems(np, "gpios");
> +		if (ngpios < 0)
> +			continue;
> +
> +		if (ngpios % ncells) {
> +			dev_warn(chip->parent,
> +				"GPIOs entries are not proper in gpios\n");
>  			continue;
> +		}
> +
> +		ngpios /= ncells;
> +		for (i = 0; i < ngpios; i++) {
> +			desc = of_parse_own_gpio(np, &name, i,
> +						 &lflags, &dflags);
> +			if (IS_ERR(desc))
> +				continue;
>  
> -		ret = gpiod_hog(desc, name, lflags, dflags);
> -		if (ret < 0)
> -			return ret;
> +			ret = gpiod_hog(desc, name, lflags, dflags);
> +			if (ret < 0)
> +				return ret;
> +		}
>  	}
>  
>  	return 0;
> -- 
> 2.1.4
> 
> --
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