On 17:59 Wed 04 Feb , Guennadi Liakhovetski wrote:
> Some SPI devices have special requirements on chip-select handling.
> With this patch we can use a GPIO as a chip-select and strictly follow
> the SPI_XFER_BEGIN and SPI_XFER_END flags.
>
> Signed-off-by: Guennadi Liakhovetski <l...@denx.de>
> ---
>
> Jean-Christophe: one more for you to ack.
>
> drivers/spi/mxc_spi.c | 35 +++++++++++++++++++++++++++++------
> 1 files changed, 29 insertions(+), 6 deletions(-)
>
> diff --git a/drivers/spi/mxc_spi.c b/drivers/spi/mxc_spi.c
> index 9267341..eacd36c 100644
> --- a/drivers/spi/mxc_spi.c
> +++ b/drivers/spi/mxc_spi.c
> @@ -32,6 +32,8 @@
>
> #else
>
> +#include <asm/arch/mx31.h>
> +
> #define MXC_CSPIRXDATA 0x00
> #define MXC_CSPITXDATA 0x04
> #define MXC_CSPICTRL 0x08
> @@ -68,6 +70,7 @@ struct mxc_spi_slave {
> struct spi_slave slave;
> unsigned long base;
> u32 ctrl_reg;
> + int gpio;
> };
>
> static inline struct mxc_spi_slave *to_mxc_spi_slave(struct spi_slave *slave)
> @@ -91,6 +94,9 @@ static u32 spi_xchg_single(struct spi_slave *slave, u32
> data,
> struct mxc_spi_slave *mxcs = to_mxc_spi_slave(slave);
> unsigned int cfg_reg = reg_read(mxcs->base + MXC_CSPICTRL);
>
> + if (mxcs->gpio > 0 && (flags & SPI_XFER_BEGIN))
> + mx31_gpio_set(mxcs->gpio, !!(mxcs->ctrl_reg &
> MXC_CSPICTRL_SSPOL));
> +
> reg_write(mxcs->base + MXC_CSPITXDATA, data);
>
> cfg_reg |= MXC_CSPICTRL_XCH;
> @@ -100,6 +106,9 @@ static u32 spi_xchg_single(struct spi_slave *slave, u32
> data,
> while (reg_read(mxcs->base + MXC_CSPICTRL) & MXC_CSPICTRL_XCH)
> ;
>
> + if (mxcs->gpio > 0 && (flags & SPI_XFER_END))
> + mx31_gpio_set(mxcs->gpio, !(mxcs->ctrl_reg &
> MXC_CSPICTRL_SSPOL));
> +
> return reg_read(mxcs->base + MXC_CSPIRXDATA);
> }
>
> @@ -175,10 +184,28 @@ struct spi_slave *spi_setup_slave(unsigned int bus,
> unsigned int cs,
> unsigned int ctrl_reg;
> struct mxc_spi_slave *mxcs;
>
> - if (bus >= sizeof(spi_bases) / sizeof(spi_bases[0]) ||
> - cs > 3)
> + if (bus >= sizeof(spi_bases) / sizeof(spi_bases[0]))
> + return NULL;
> +
> + mxcs = malloc(sizeof(struct mxc_spi_slave));
> + if (!mxcs)
> return NULL;
>
> + /*
> + * Some SPI devices require active chip-select over multiple
> + * transactions, we achieve this using a GPIO. Still, the SPI
> + * controller has to be configured to use one of its own chipselects.
> + * To use this feature you have to call spi_setup_slave() with
> + * cs = internal_cs | (gpio << 8), and you have to use some unused
> + * on this SPI controller cs between 0 and 3.
> + */
> + if (cs > 3) {
> + mxcs->gpio = cs >> 8;
> + cs &= 3;
> + mx31_gpio_direction(mxcs->gpio, MX31_GPIO_DIRECTION_OUT);
> + } else
> + mxcs->gpio = -1;
> +
why not add a callback for the chipselect instead
as example if you have to use a gpio extender it will simplest to implent
instead of hack the SPI driver
Best Regars,
J.
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