[PATCH v2] spi: Fix probing SPI drivers with no cs-gpios

[Sascha Hauer]

On Wed, Jan 25, 2023 at 07:05:55AM +1100, John Watts wrote:
> of_gpio_named_count returns a negative value on error but this
> is discarded and cast to a u16, making error handling impossible.
> 
> With debug logging enabled this effectively halts booting so the board can
> print an error over serial 65534 times.
> 
> Introduce of_gpio_count_csgpios which returns 0 in the case of an error
> rather than a negative value.
> 
> Signed-off-by: John Watts <contact at jookia.org>
> ---
> Changes v1 -> v2:
> - Refactored logic in to separate of_gpio_count_csgpios function
> ---

Applied, thanks

Sascha

>  drivers/spi/atmel_spi.c |  2 +-
>  drivers/spi/imx_spi.c   |  2 +-
>  drivers/spi/stm32_spi.c |  2 +-
>  include/of_gpio.h       | 17 +++++++++++++++++
>  4 files changed, 20 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/spi/atmel_spi.c b/drivers/spi/atmel_spi.c
> index 399c47c81d..9bf85874c5 100644
> --- a/drivers/spi/atmel_spi.c
> +++ b/drivers/spi/atmel_spi.c
> @@ -408,7 +408,7 @@ static int atmel_spi_probe(struct device *dev)
>  		master->num_chipselect = pdata->num_chipselect;
>  		as->cs_pins = pdata->chipselect;
>  	} else {
> -		master->num_chipselect = of_gpio_named_count(node, "cs-gpios");
> +		master->num_chipselect = of_gpio_count_csgpios(node);
>  		as->cs_pins = xzalloc(sizeof(u32) * master->num_chipselect);
>  
>  		for (i = 0; i < master->num_chipselect; i++) {
> diff --git a/drivers/spi/imx_spi.c b/drivers/spi/imx_spi.c
> index eb30d757d5..f81d9e851f 100644
> --- a/drivers/spi/imx_spi.c
> +++ b/drivers/spi/imx_spi.c
> @@ -568,7 +568,7 @@ static int imx_spi_dt_probe(struct imx_spi *imx)
>  	if (!node)
>  		return -ENODEV;
>  
> -	imx->master.num_chipselect = of_gpio_named_count(node, "cs-gpios");
> +	imx->master.num_chipselect = of_gpio_count_csgpios(node);
>  	imx->cs_array = xzalloc(sizeof(u32) * imx->master.num_chipselect);
>  
>  	for (i = 0; i < imx->master.num_chipselect; i++)
> diff --git a/drivers/spi/stm32_spi.c b/drivers/spi/stm32_spi.c
> index 821a95980f..0d7407c279 100644
> --- a/drivers/spi/stm32_spi.c
> +++ b/drivers/spi/stm32_spi.c
> @@ -514,7 +514,7 @@ static void stm32_spi_dt_probe(struct stm32_spi_priv *priv)
>  	struct device_node *node = priv->master.dev->of_node;
>  	int i;
>  
> -	priv->master.num_chipselect = of_gpio_named_count(node, "cs-gpios");
> +	priv->master.num_chipselect = of_gpio_count_csgpios(node);
>  	priv->cs_gpios = xzalloc(sizeof(u32) * priv->master.num_chipselect);
>  
>  	for (i = 0; i < priv->master.num_chipselect; i++)
> diff --git a/include/of_gpio.h b/include/of_gpio.h
> index 30ff204baf..794a9926cd 100644
> --- a/include/of_gpio.h
> +++ b/include/of_gpio.h
> @@ -69,6 +69,23 @@ static inline int of_gpio_count(struct device_node *np)
>  	return of_gpio_named_count(np, "gpios");
>  }
>  
> +/**
> + * of_gpio_count() - Count cs-gpios for a device
> + * @np:		device node to count cs-gpios for
> + *
> + * Same as of_gpio_named_count, but hard coded to use the 'cs-gpios' property
> + * Returns 0 on error
> + */
> +static inline int of_gpio_count_csgpios(struct device_node *np)
> +{
> +	int count = of_gpio_named_count(np, "cs-gpios");
> +
> +	if (count > 0)
> +		return count;
> +	else
> +		return 0;
> +}
> +
>  static inline int of_get_gpio_flags(struct device_node *np, int index,
>  		      enum of_gpio_flags *flags)
>  {
> -- 
> 2.39.0
> 
> 
> 

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