spi_gpio.h

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#ifndef __LINUX_SPI_GPIO_H
#define __LINUX_SPI_GPIO_H

/*
 * For each bitbanged SPI bus, set up a platform_device node with:
 *   - name "spi_gpio"
 *   - id the same as the SPI bus number it implements
 *   - dev.platform data pointing to a struct spi_gpio_platform_data
 *
 * Or, see the driver code for information about speedups that are
 * possible on platforms that support inlined access for GPIOs (no
 * spi_gpio_platform_data is used).
 *
 * Use spi_board_info with these busses in the usual way, being sure
 * that the controller_data being the GPIO used for each device's
 * chipselect:
 *
 *  static struct spi_board_info ... [] = {
 *  ...
 *      // this slave uses GPIO 42 for its chipselect
 *      .controller_data = (void *) 42,
 *  ...
 *      // this one uses GPIO 86 for its chipselect
 *      .controller_data = (void *) 86,
 *  ...
 *  };
 *
 * If chipselect is not used (there's only one device on the bus), assign
 * SPI_GPIO_NO_CHIPSELECT to the controller_data:
 *      .controller_data = (void *) SPI_GPIO_NO_CHIPSELECT;
 *
 * If the MISO or MOSI pin is not available then it should be set to
 * SPI_GPIO_NO_MISO or SPI_GPIO_NO_MOSI.
 *
 * If the bitbanged bus is later switched to a "native" controller,
 * that platform_device and controller_data should be removed.
 */

#define SPI_GPIO_NO_CHIPSELECT      ((unsigned long)-1l)
#define SPI_GPIO_NO_MISO        ((unsigned long)-1l)
#define SPI_GPIO_NO_MOSI        ((unsigned long)-1l)

struct spi_gpio_platform_data {
    unsigned    sck;
    unsigned    mosi;
    unsigned    miso;

    u16     num_chipselect;
};

#endif /* __LINUX_SPI_GPIO_H */