72 строки
2.5 KiB
C
72 строки
2.5 KiB
C
#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 - parameter for bitbanged SPI master
|
|
* @sck: number of the GPIO used for clock output
|
|
* @mosi: number of the GPIO used for Master Output, Slave In (MOSI) data
|
|
* @miso: number of the GPIO used for Master Input, Slave Output (MISO) data
|
|
* @num_chipselect: how many slaves to allow
|
|
*
|
|
* All GPIO signals used with the SPI bus managed through this driver
|
|
* (chipselects, MOSI, MISO, SCK) must be configured as GPIOs, instead
|
|
* of some alternate function.
|
|
*
|
|
* It can be convenient to use this driver with pins that have alternate
|
|
* functions associated with a "native" SPI controller if a driver for that
|
|
* controller is not available, or is missing important functionality.
|
|
*
|
|
* On platforms which can do so, configure MISO with a weak pullup unless
|
|
* there's an external pullup on that signal. That saves power by avoiding
|
|
* floating signals. (A weak pulldown would save power too, but many
|
|
* drivers expect to see all-ones data as the no slave "response".)
|
|
*/
|
|
struct spi_gpio_platform_data {
|
|
unsigned sck;
|
|
unsigned long mosi;
|
|
unsigned long miso;
|
|
|
|
u16 num_chipselect;
|
|
};
|
|
|
|
#endif /* __LINUX_SPI_GPIO_H */
|