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 Index: linux-2.6.28.2/drivers/spi/spi_gpio.c
   8 ===================================================================
   9 --- linux-2.6.28.2.orig/drivers/spi/spi_gpio.c  2009-02-11 18:48:23.000000000 +0100
  10 +++ linux-2.6.28.2/drivers/spi/spi_gpio.c       2009-02-11 18:48:50.000000000 +0100
  11 @@ -178,8 +178,10 @@ static void spi_gpio_chipselect(struct s
  12         if (is_active)
  13                 setsck(spi, spi->mode & SPI_CPOL);
  14
  15 -       /* SPI is normally active-low */
  16 -       gpio_set_value(cs, (spi->mode & SPI_CS_HIGH) ? is_active : !is_active);
  17 +       if (cs != SPI_GPIO_NO_CHIPSELECT) {
  18 +               /* SPI is normally active-low */
  19 +               gpio_set_value(cs, (spi->mode & SPI_CS_HIGH) ? is_active : !is_active);
  20 +       }
  21  }
  22
  23  static int spi_gpio_setup(struct spi_device *spi)
  24 @@ -191,15 +193,17 @@ static int spi_gpio_setup(struct spi_dev
  25                 return -EINVAL;
  26
  27         if (!spi->controller_state) {
  28 -               status = gpio_request(cs, spi->dev.bus_id);
  29 -               if (status)
  30 -                       return status;
  31 -               status = gpio_direction_output(cs, spi->mode & SPI_CS_HIGH);
  32 +               if (cs != SPI_GPIO_NO_CHIPSELECT) {
  33 +                       status = gpio_request(cs, spi->dev.bus_id);
  34 +                       if (status)
  35 +                               return status;
  36 +                       status = gpio_direction_output(cs, spi->mode & SPI_CS_HIGH);
  37 +               }
  38         }
  39         if (!status)
  40                 status = spi_bitbang_setup(spi);
  41         if (status) {
  42 -               if (!spi->controller_state)
  43 +               if (!spi->controller_state && cs != SPI_GPIO_NO_CHIPSELECT)
  44                         gpio_free(cs);
  45         }
  46         return status;
  47 @@ -209,7 +213,8 @@ static void spi_gpio_cleanup(struct spi_
  48  {
  49         unsigned long   cs = (unsigned long) spi->controller_data;
  50
  51 -       gpio_free(cs);
  52 +       if (cs != SPI_GPIO_NO_CHIPSELECT)
  53 +               gpio_free(cs);
  54         spi_bitbang_cleanup(spi);
  55  }
  56
  57 Index: linux-2.6.28.2/include/linux/spi/spi_gpio.h
  58 ===================================================================
  59 --- linux-2.6.28.2.orig/include/linux/spi/spi_gpio.h    2009-02-11 18:48:23.000000000 +0100
  60 +++ linux-2.6.28.2/include/linux/spi/spi_gpio.h 2009-02-11 18:58:31.000000000 +0100
  61 @@ -25,10 +25,16 @@
  62   *     ...
  63   *     };
  64   *
  65 + * If chipselect is not used (there's only one device on the bus), assign
  66 + * SPI_GPIO_NO_CHIPSELECT to the controller_data:
  67 + *             .controller_data = (void *) SPI_GPIO_NO_CHIPSELECT;
  68 + *
  69   * If the bitbanged bus is later switched to a "native" controller,
  70   * that platform_device and controller_data should be removed.
  71   */
  72
  73 +#define SPI_GPIO_NO_CHIPSELECT         ((unsigned long)-1l)
  74 +
  75  /**
  76   * struct spi_gpio_platform_data - parameter for bitbanged SPI master
  77   * @sck: number of the GPIO used for clock output