Re: [PATCH] mcspi: Add support for GPIO chip select lines

[Grant Likely <grant.likely@secretlab.ca>]

On Tue, Dec 21, 2010 at 10:56 AM, Ben Gamari <bgamari.foss@gmail.com> wrote:
> This mechanism is in large part stolen from the s3c64xx-spi module. To
> use this functionality, one simply must define a set_level function to
> set the CS state and a omap2_mcspi_csinfo struct for each chip select in
> the board file.
>
> Each spi_board_info.controller_data should then be set
> to point to the appropriate csinfo struct. This will cause the driver to
> call the csinfo->set_level function instead of toggling the McSPI chip
> select lines.
>
> Signed-off-by: Ben Gamari <bgamari.foss@gmail.com>

I'd rather see the spi driver modified to use the gpio api directly.
The drivers are already tending in that direction and it doesn't
require machine specific set_level functions to be defined.

g.

> ---
>  arch/arm/plat-omap/include/plat/mcspi.h |   14 ++++++++++++++
>  drivers/spi/omap2_mcspi.c               |   14 +++++++++-----
>  2 files changed, 23 insertions(+), 5 deletions(-)
>
> diff --git a/arch/arm/plat-omap/include/plat/mcspi.h b/arch/arm/plat-omap/include/plat/mcspi.h
> index 1254e49..ab84b8d 100644
> --- a/arch/arm/plat-omap/include/plat/mcspi.h
> +++ b/arch/arm/plat-omap/include/plat/mcspi.h
> @@ -1,6 +1,20 @@
>  #ifndef _OMAP2_MCSPI_H
>  #define _OMAP2_MCSPI_H
>
> +/**
> + * struct omap2_mcspi_csinfo - Chip Select description
> + * @line: Custom 'identity' of the CS line
> + * @set_level: Function to set the state of a given CS line
> + *
> + * This is to allow use of GPIO lines as CS lines. Allocate and initialize one
> + * in the machine init code and make spi_board_info.controller_data point to
> + * it.
> + */
> +struct omap2_mcspi_csinfo {
> +        unsigned line;
> +        void (*set_level)(unsigned line_id, int lvl);
> +};
> +
>  struct omap2_mcspi_platform_config {
>        unsigned short  num_cs;
>  };
> diff --git a/drivers/spi/omap2_mcspi.c b/drivers/spi/omap2_mcspi.c
> index 2a651e6..92ccbd6 100644
> --- a/drivers/spi/omap2_mcspi.c
> +++ b/drivers/spi/omap2_mcspi.c
> @@ -35,6 +35,7 @@
>  #include <linux/slab.h>
>
>  #include <linux/spi/spi.h>
> +#include <linux/gpio.h>
>
>  #include <plat/dma.h>
>  #include <plat/clock.h>
> @@ -235,11 +236,14 @@ static void omap2_mcspi_set_enable(const struct spi_device *spi, int enable)
>
>  static void omap2_mcspi_force_cs(struct spi_device *spi, int cs_active)
>  {
> -       u32 l;
> -
> -       l = mcspi_cached_chconf0(spi);
> -       MOD_REG_BIT(l, OMAP2_MCSPI_CHCONF_FORCE, cs_active);
> -       mcspi_write_chconf0(spi, l);
> +       if (spi->controller_data) {
> +               struct omap2_mcspi_csinfo *csinfo = spi->controller_data;
> +               (*csinfo->set_level)(csinfo->line, cs_active);
> +       } else {
> +               u32 l = mcspi_cached_chconf0(spi);
> +               MOD_REG_BIT(l, OMAP2_MCSPI_CHCONF_FORCE, cs_active);
> +               mcspi_write_chconf0(spi, l);
> +       }
>  }
>
>  static void omap2_mcspi_set_master_mode(struct spi_master *master)
> --
> 1.7.1
>
>



-- 
Grant Likely, B.Sc., P.Eng.
Secret Lab Technologies Ltd.
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