[PATCH v2] spi: mvebu_a3700_spi: add support for cs-gpios

[Stefan Roese]

Hi George,

thanks for the new version. One nitpicking comment below...

On 29.09.20 20:34, George Hilliard wrote:
> The device tree has a way to specify GPIO lines as chip selects.  From
> the binding docs:
> 
>      So if for example the controller has 2 CS lines, and the cs-gpios
>      property looks like this:
> 
>      cs-gpios = <&gpio1 0 0> <0> <&gpio1 1 0> <&gpio1 2 0>;
> 
>      Then it should be configured so that num_chipselect = 4 with the
>      following mapping:
> 
>      cs0 : &gpio1 0 0
>      cs1 : native
>      cs2 : &gpio1 1 0
>      cs3 : &gpio1 2 0
> 
> Add support for this, while retaining backward-compatibility with
> existing device trees; the driver will preserve existing behavior if a
> cs-gpios list is not given, or if a particular line is specified as <0>
> (native).
> 
> This implementation is inspired by similar implementations in
> neighboring drivers for other platforms: atmega, mxc, etc.
> 
> Signed-off-by: George Hilliard <ghilliar at amazon.com>
> ---
>   drivers/spi/mvebu_a3700_spi.c | 40 +++++++++++++++++++++++++++++------
>   1 file changed, 34 insertions(+), 6 deletions(-)
> 
> diff --git a/drivers/spi/mvebu_a3700_spi.c b/drivers/spi/mvebu_a3700_spi.c
> index e860b9ec64..b82ed2ce7a 100644
> --- a/drivers/spi/mvebu_a3700_spi.c
> +++ b/drivers/spi/mvebu_a3700_spi.c
> @@ -15,6 +15,7 @@
>   #include <asm/io.h>
>   #include <dm/device_compat.h>
>   #include <linux/bitops.h>
> +#include <asm/gpio.h>
>   
>   DECLARE_GLOBAL_DATA_PTR;
>   
> @@ -27,6 +28,7 @@ DECLARE_GLOBAL_DATA_PTR;
>   #define MVEBU_SPI_A3700_SPI_EN_0		BIT(16)
>   #define MVEBU_SPI_A3700_CLK_PRESCALE_MASK	0x1f
>   
> +#define MAX_CS_COUNT	4
>   
>   /* SPI registers */
>   struct spi_reg {
> @@ -39,16 +41,23 @@ struct spi_reg {
>   struct mvebu_spi_platdata {
>   	struct spi_reg *spireg;
>   	struct clk clk;
> +	struct gpio_desc cs_gpios[MAX_CS_COUNT];
>   };
>   
> -static void spi_cs_activate(struct spi_reg *reg, int cs)
> +static void spi_cs_activate(struct mvebu_spi_platdata *plat, int cs)
>   {
> -	setbits_le32(&reg->ctrl, MVEBU_SPI_A3700_SPI_EN_0 << cs);
> +	if (CONFIG_IS_ENABLED(DM_GPIO) && dm_gpio_is_valid(&plat->cs_gpios[cs]))
> +		dm_gpio_set_value(&plat->cs_gpios[cs], 1);
> +	else
> +		setbits_le32(&plat->spireg->ctrl, MVEBU_SPI_A3700_SPI_EN_0 << cs);
>   }
>   
> -static void spi_cs_deactivate(struct spi_reg *reg, int cs)
> +static void spi_cs_deactivate(struct mvebu_spi_platdata *plat, int cs)
>   {
> -	clrbits_le32(&reg->ctrl, MVEBU_SPI_A3700_SPI_EN_0 << cs);
> +	if (CONFIG_IS_ENABLED(DM_GPIO) && dm_gpio_is_valid(&plat->cs_gpios[cs]))
> +		dm_gpio_set_value(&plat->cs_gpios[cs], 0);
> +	else
> +		clrbits_le32(&plat->spireg->ctrl, MVEBU_SPI_A3700_SPI_EN_0 << cs);
>   }
>   
>   /**
> @@ -150,7 +159,7 @@ static int mvebu_spi_xfer(struct udevice *dev, unsigned int bitlen,
>   	/* Activate CS */
>   	if (flags & SPI_XFER_BEGIN) {
>   		debug("SPI: activate cs.\n");
> -		spi_cs_activate(reg, spi_chip_select(dev));
> +		spi_cs_activate(plat, spi_chip_select(dev));
>   	}
>   
>   	/* Send and/or receive */
> @@ -169,7 +178,7 @@ static int mvebu_spi_xfer(struct udevice *dev, unsigned int bitlen,
>   			return ret;
>   
>   		debug("SPI: deactivate cs.\n");
> -		spi_cs_deactivate(reg, spi_chip_select(dev));
> +		spi_cs_deactivate(plat, spi_chip_select(dev));
>   	}
>   
>   	return 0;
> @@ -247,6 +256,25 @@ static int mvebu_spi_probe(struct udevice *bus)
>   
>   	writel(data, &reg->cfg);
>   
> +	/* Set up CS GPIOs in device tree, if any */
> +	if (CONFIG_IS_ENABLED(DM_GPIO) && gpio_get_list_count(bus, "cs-gpios") > 0) {
> +		int i;
> +
> +		for (i = 0; i < ARRAY_SIZE(plat->cs_gpios); i++) {
> +			ret = gpio_request_by_name(bus, "cs-gpios", i, &plat->cs_gpios[i], 0);
> +			if (ret < 0 || !dm_gpio_is_valid(&plat->cs_gpios[i]))
> +				// Use the native CS function for this line
> +				continue;

Why do you introduce here C++ style comments? Even though they are
not banned any more (AFAIK), I see no reason to add multiple
comment styles in such a small patch. Additionally this is a multi-
line statement after the "if" and it needs parenthesis.

Other than that, please feel free to add my:

Reviewed-by: Stefan Roese <sr at denx.de>

to the next version.

Thanks,
Stefan

> +
> +			ret = dm_gpio_set_dir_flags(&plat->cs_gpios[i],
> +						    GPIOD_IS_OUT | GPIOD_ACTIVE_LOW);
> +			if (ret) {
> +				dev_err(bus, "Setting cs %d error\n", i);
> +				return ret;
> +			}
> +		}
> +	}
> +
>   	return 0;
>   }
>   
> 


Viele Grüße,
Stefan

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