diff options
Diffstat (limited to 'include/linux/spi/spi.h')
| -rw-r--r-- | include/linux/spi/spi.h | 59 |
1 files changed, 58 insertions, 1 deletions
diff --git a/include/linux/spi/spi.h b/include/linux/spi/spi.h index 302b81d1d11..002a3cddbdd 100644 --- a/include/linux/spi/spi.h +++ b/include/linux/spi/spi.h @@ -77,6 +77,7 @@ struct spi_device { #define SPI_CS_HIGH 0x04 /* chipselect active high? */ #define SPI_LSB_FIRST 0x08 /* per-word bits-on-wire */ #define SPI_3WIRE 0x10 /* SI/SO signals shared */ +#define SPI_LOOP 0x20 /* loopback mode */ u8 bits_per_word; int irq; void *controller_state; @@ -138,6 +139,32 @@ struct spi_message; +/** + * struct spi_driver - Host side "protocol" driver + * @probe: Binds this driver to the spi device. Drivers can verify + * that the device is actually present, and may need to configure + * characteristics (such as bits_per_word) which weren't needed for + * the initial configuration done during system setup. + * @remove: Unbinds this driver from the spi device + * @shutdown: Standard shutdown callback used during system state + * transitions such as powerdown/halt and kexec + * @suspend: Standard suspend callback used during system state transitions + * @resume: Standard resume callback used during system state transitions + * @driver: SPI device drivers should initialize the name and owner + * field of this structure. + * + * This represents the kind of device driver that uses SPI messages to + * interact with the hardware at the other end of a SPI link. It's called + * a "protocol" driver because it works through messages rather than talking + * directly to SPI hardware (which is what the underlying SPI controller + * driver does to pass those messages). These protocols are defined in the + * specification for the device(s) supported by the driver. + * + * As a rule, those device protocols represent the lowest level interface + * supported by a driver, and it will support upper level interfaces too. + * Examples of such upper levels include frameworks like MTD, networking, + * MMC, RTC, filesystem character device nodes, and hardware monitoring. + */ struct spi_driver { int (*probe)(struct spi_device *spi); int (*remove)(struct spi_device *spi); @@ -667,7 +694,37 @@ static inline ssize_t spi_w8r16(struct spi_device *spi, u8 cmd) * parport adapters, or microcontrollers acting as USB-to-SPI bridges. */ -/* board-specific information about each SPI device */ +/** + * struct spi_board_info - board-specific template for a SPI device + * @modalias: Initializes spi_device.modalias; identifies the driver. + * @platform_data: Initializes spi_device.platform_data; the particular + * data stored there is driver-specific. + * @controller_data: Initializes spi_device.controller_data; some + * controllers need hints about hardware setup, e.g. for DMA. + * @irq: Initializes spi_device.irq; depends on how the board is wired. + * @max_speed_hz: Initializes spi_device.max_speed_hz; based on limits + * from the chip datasheet and board-specific signal quality issues. + * @bus_num: Identifies which spi_master parents the spi_device; unused + * by spi_new_device(), and otherwise depends on board wiring. + * @chip_select: Initializes spi_device.chip_select; depends on how + * the board is wired. + * @mode: Initializes spi_device.mode; based on the chip datasheet, board + * wiring (some devices support both 3WIRE and standard modes), and + * possibly presence of an inverter in the chipselect path. + * + * When adding new SPI devices to the device tree, these structures serve + * as a partial device template. They hold information which can't always + * be determined by drivers. Information that probe() can establish (such + * as the default transfer wordsize) is not included here. + * + * These structures are used in two places. Their primary role is to + * be stored in tables of board-specific device descriptors, which are + * declared early in board initialization and then used (much later) to + * populate a controller's device tree after the that controller's driver + * initializes. A secondary (and atypical) role is as a parameter to + * spi_new_device() call, which happens after those controller drivers + * are active in some dynamic board configuration models. + */ struct spi_board_info { /* the device name and module name are coupled, like platform_bus; * "modalias" is normally the driver name. |