Re: [PATCH 1/2 v2] spi: s3c64xx: use "cs-gpios" from spi node instead of "cs-gpio"

[Sylwester Nawrocki <s.nawrocki@samsung.com>]

On 10/06/14 12:08, Naveen Krishna Chatradhi wrote:
> Currently, spi-s3c64xx.c needs "cs-gpio" chip select GPIO to be
> defined under "controller-data" node under each slave node.
> 
> &spi_x {
> 	cs-gpios <>;
> 	...
> 	slave_node {
> 
> 		controller-data {
> 			cs-gpio = <>;
> 			...
> 		};
> 		...
> 	};
> 	...
> };
> 
> Where as, SPI core and many other drivers uses "cs-gpios" for
> from device tree node.
> 
> Hence, make changes in spi-s3c64xx.c driver to make use of
> "cs-gpios" from SPI node(parent) instead of "cs-gpio" defined in
> slaves "controller-data"(child) node.
> 
> Also updates the Device tree Documentation.
> 
> Signed-off-by: Naveen Krishna Chatradhi <ch.naveen@samsung.com>
> Cc: Javier Martinez Canillas <javier.martinez@collabora.co.uk>
> Cc: Doug Anderson <dianders@chromium.org>
> ---
> Changes since v1:
> 1. fixed a compilation warning thus squashing the other patch into this.
> 2. Updated device tree description in spi-samsung.txt
> 
>  .../devicetree/bindings/spi/spi-samsung.txt        |    8 ++-
>  drivers/spi/spi-s3c64xx.c                          |   56 ++++++++++++--------
>  2 files changed, 38 insertions(+), 26 deletions(-)
> 
> diff --git a/Documentation/devicetree/bindings/spi/spi-samsung.txt b/Documentation/devicetree/bindings/spi/spi-samsung.txt
> index 86aa061..13bfcb5 100644
> --- a/Documentation/devicetree/bindings/spi/spi-samsung.txt
> +++ b/Documentation/devicetree/bindings/spi/spi-samsung.txt
> @@ -42,15 +42,13 @@ Optional Board Specific Properties:
>  - num-cs: Specifies the number of chip select lines supported. If
>    not specified, the default number of chip select lines is set to 1.
>  
> +- cs-gpios: should specify GPIOs used for chipselects (see spi-bus.txt)
> +
>  SPI Controller specific data in SPI slave nodes:
>  
>  - The spi slave nodes should provide the following information which is required
>    by the spi controller.
>  
> -  - cs-gpio: A gpio specifier that specifies the gpio line used as
> -    the slave select line by the spi controller. The format of the gpio
> -    specifier depends on the gpio controller.
> -
>    - samsung,spi-feedback-delay: The sampling phase shift to be applied on the
>      miso line (to account for any lag in the miso line). The following are the
>      valid values.
> @@ -85,6 +83,7 @@ Example:
>  		#size-cells = <0>;
>  		pinctrl-names = "default";
>  		pinctrl-0 = <&spi0_bus>;
> +		cs-gpios = <&gpa2 5 1 0 3>;

While at it, please change the GPIO specifier format, this one is not
valid any more.

>  		w25q80bw@0 {
>  			#address-cells = <1>;
> @@ -94,7 +93,6 @@ Example:
>  			spi-max-frequency = <10000>;
>  
>  			controller-data {
> -				cs-gpio = <&gpa2 5 1 0 3>;
>  				samsung,spi-feedback-delay = <0>;
>  			};
>  
> diff --git a/drivers/spi/spi-s3c64xx.c b/drivers/spi/spi-s3c64xx.c
> index 75a5696..4594dde 100644
> --- a/drivers/spi/spi-s3c64xx.c
> +++ b/drivers/spi/spi-s3c64xx.c
> @@ -750,47 +750,56 @@ static int s3c64xx_spi_transfer_one(struct spi_master *master,
>  }
>  
>  static struct s3c64xx_spi_csinfo *s3c64xx_get_slave_ctrldata(
> -				struct spi_device *spi)
> +				struct spi_device *spi,
> +				struct s3c64xx_spi_csinfo *cs)
>  {
> -	struct s3c64xx_spi_csinfo *cs;
> -	struct device_node *slave_np, *data_np = NULL;
> -	struct s3c64xx_spi_driver_data *sdd;
> +	struct device_node *data_np = NULL;
>  	u32 fb_delay = 0;
>  
> -	sdd = spi_master_get_devdata(spi->master);
> -	slave_np = spi->dev.of_node;
> -	if (!slave_np) {
> -		dev_err(&spi->dev, "device node not found\n");
> +	data_np = of_get_child_by_name(spi->dev.of_node, "controller-data");
> +	if (!data_np) {
> +		dev_err(&spi->dev, "child node 'controller-data' not found\n");
>  		return ERR_PTR(-EINVAL);
>  	}
>  
> -	data_np = of_get_child_by_name(slave_np, "controller-data");
> -	if (!data_np) {
> -		dev_err(&spi->dev, "child node 'controller-data' not found\n");
> +	of_property_read_u32(data_np, "samsung,spi-feedback-delay", &fb_delay);
> +	cs->fb_delay = fb_delay;
> +	of_node_put(data_np);
> +
> +	return cs;
> +}
> +
> +static struct s3c64xx_spi_csinfo *s3c64xx_get_cs_gpios(struct spi_device *spi)
> +{
> +	struct device_node *parent_np = NULL;
> +	struct s3c64xx_spi_driver_data *sdd;
> +	struct s3c64xx_spi_csinfo *cs;
> +
> +	parent_np = of_get_parent(spi->dev.of_node);
> +	if (!parent_np) {
> +		dev_err(&spi->dev, "Parent node not found\n");
>  		return ERR_PTR(-EINVAL);
>  	}
>  
> +	sdd = spi_master_get_devdata(spi->master);
> +
>  	cs = kzalloc(sizeof(*cs), GFP_KERNEL);
>  	if (!cs) {
> -		of_node_put(data_np);
> +		of_node_put(parent_np);
>  		return ERR_PTR(-ENOMEM);
>  	}
>  
>  	/* The CS line is asserted/deasserted by the gpio pin */
>  	if (sdd->cs_gpio)
> -		cs->line = of_get_named_gpio(data_np, "cs-gpio", 0);
> +		cs->line = of_get_named_gpio(parent_np, "cs-gpios", 0);

Can we support both "cs-gpio" and "cs-gpios" for backward compatibility ?
After your change all DTBs using the original pattern will not work with
new kernels any more. At least I would expect such backward compatibility
maintained for few kernel releases.

>  	if (!gpio_is_valid(cs->line)) {
>  		dev_err(&spi->dev, "chip select gpio is not specified or invalid\n");
> -		kfree(cs);
> -		of_node_put(data_np);
> +		of_node_put(parent_np);
>  		return ERR_PTR(-EINVAL);
>  	}
>  
> -	of_property_read_u32(data_np, "samsung,spi-feedback-delay", &fb_delay);
> -	cs->fb_delay = fb_delay;
> -	of_node_put(data_np);
> -	return cs;
> +	return s3c64xx_get_slave_ctrldata(spi, cs);
>  }
>  
>  /*
> @@ -806,9 +815,14 @@ static int s3c64xx_spi_setup(struct spi_device *spi)
>  	struct s3c64xx_spi_info *sci;
>  	int err;
>  
> +	if (!spi->dev.of_node) {
> +		dev_err(&spi->dev, "device node not found\n");
> +		return -EINVAL;
> +	}
> +
>  	sdd = spi_master_get_devdata(spi->master);
>  	if (!cs && spi->dev.of_node) {
> -		cs = s3c64xx_get_slave_ctrldata(spi);
> +		cs = s3c64xx_get_cs_gpios(spi);
>  		spi->controller_data = cs;
>  	}
>  
> @@ -1077,7 +1091,7 @@ static int s3c64xx_spi_probe(struct platform_device *pdev)
>  	sdd->sfr_start = mem_res->start;
>  	sdd->cs_gpio = true;
>  	if (pdev->dev.of_node) {
> -		if (!of_find_property(pdev->dev.of_node, "cs-gpio", NULL))
> +		if (!of_find_property(pdev->dev.of_node, "cs-gpios", NULL))
>  			sdd->cs_gpio = false;

Ditto.

>  		ret = of_alias_get_id(pdev->dev.of_node, "spi");

--
Thanks!
Sylwester