target/linux/generic-2.6/patches-2.6.28/920-02-spi-gpio-without-cs.patch

   1 Optionally omit the CS signal, if there's only one device on the bus.
   2
   3 --mb
   4
   5
   6
   7 --- a/drivers/spi/spi_gpio.c
   8 +++ b/drivers/spi/spi_gpio.c
   9 @@ -178,8 +178,10 @@ static void spi_gpio_chipselect(struct s
  10         if (is_active)
  11                 setsck(spi, spi->mode & SPI_CPOL);
  12
  13 -       /* SPI is normally active-low */
  14 -       gpio_set_value(cs, (spi->mode & SPI_CS_HIGH) ? is_active : !is_active);
  15 +       if (cs != SPI_GPIO_NO_CHIPSELECT) {
  16 +               /* SPI is normally active-low */
  17 +               gpio_set_value(cs, (spi->mode & SPI_CS_HIGH) ? is_active : !is_active);
  18 +       }
  19  }
  20
  21  static int spi_gpio_setup(struct spi_device *spi)
  22 @@ -191,15 +193,17 @@ static int spi_gpio_setup(struct spi_dev
  23                 return -EINVAL;
  24
  25         if (!spi->controller_state) {
  26 -               status = gpio_request(cs, spi->dev.bus_id);
  27 -               if (status)
  28 -                       return status;
  29 -               status = gpio_direction_output(cs, spi->mode & SPI_CS_HIGH);
  30 +               if (cs != SPI_GPIO_NO_CHIPSELECT) {
  31 +                       status = gpio_request(cs, spi->dev.bus_id);
  32 +                       if (status)
  33 +                               return status;
  34 +                       status = gpio_direction_output(cs, spi->mode & SPI_CS_HIGH);
  35 +               }
  36         }
  37         if (!status)
  38                 status = spi_bitbang_setup(spi);
  39         if (status) {
  40 -               if (!spi->controller_state)
  41 +               if (!spi->controller_state && cs != SPI_GPIO_NO_CHIPSELECT)
  42                         gpio_free(cs);
  43         }
  44         return status;
  45 @@ -209,7 +213,8 @@ static void spi_gpio_cleanup(struct spi_
  46  {
  47         unsigned long   cs = (unsigned long) spi->controller_data;
  48
  49 -       gpio_free(cs);
  50 +       if (cs != SPI_GPIO_NO_CHIPSELECT)
  51 +               gpio_free(cs);
  52         spi_bitbang_cleanup(spi);
  53  }
  54
  55 --- a/include/linux/spi/spi_gpio.h
  56 +++ b/include/linux/spi/spi_gpio.h
  57 @@ -25,10 +25,16 @@
  58   *     ...
  59   *     };
  60   *
  61 + * If chipselect is not used (there's only one device on the bus), assign
  62 + * SPI_GPIO_NO_CHIPSELECT to the controller_data:
  63 + *             .controller_data = (void *) SPI_GPIO_NO_CHIPSELECT;
  64 + *
  65   * If the bitbanged bus is later switched to a "native" controller,
  66   * that platform_device and controller_data should be removed.
  67   */
  68
  69 +#define SPI_GPIO_NO_CHIPSELECT         ((unsigned long)-1l)
  70 +
  71  /**
  72   * struct spi_gpio_platform_data - parameter for bitbanged SPI master
  73   * @sck: number of the GPIO used for clock output