#define SPI_MODE_3 (SPI_CPOL|SPI_CPHA)
#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;
+/**
+ * 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);
/**
* struct spi_master - interface to SPI master controller
- * @cdev: class interface to this driver
+ * @dev: device interface to this driver
* @bus_num: board-specific (and often SOC-specific) identifier for a
* given SPI controller.
* @num_chipselect: chipselects are used to distinguish individual
* message's completion function when the transaction completes.
*/
struct spi_master {
- struct class_device cdev;
+ struct device dev;
/* other than negative (== assign one dynamically), bus_num is fully
* board-specific. usually that simplifies to being SOC-specific.
static inline void *spi_master_get_devdata(struct spi_master *master)
{
- return class_get_devdata(&master->cdev);
+ return dev_get_drvdata(&master->dev);
}
static inline void spi_master_set_devdata(struct spi_master *master, void *data)
{
- class_set_devdata(&master->cdev, data);
+ dev_set_drvdata(&master->dev, data);
}
static inline struct spi_master *spi_master_get(struct spi_master *master)
{
- if (!master || !class_device_get(&master->cdev))
+ if (!master || !get_device(&master->dev))
return NULL;
return master;
}
static inline void spi_master_put(struct spi_master *master)
{
if (master)
- class_device_put(&master->cdev);
+ put_device(&master->dev);
}
* chip transactions together.
*
* (ii) When the transfer is the last one in the message, the chip may
- * stay selected until the next transfer. This is purely a performance
- * hint; the controller driver may need to select a different device
- * for the next message.
+ * stay selected until the next transfer. On multi-device SPI busses
+ * with nothing blocking messages going to other devices, this is just
+ * a performance hint; starting a message to another device deselects
+ * this one. But in other cases, this can be used to ensure correctness.
+ * Some devices need protocol transactions to be built from a series of
+ * spi_message submissions, where the content of one message is determined
+ * by the results of previous messages and where the whole transaction
+ * ends when the chipselect goes intactive.
*
* The code that submits an spi_message (and its spi_transfers)
* to the lower layers is responsible for managing its memory.
/**
* spi_setup - setup SPI mode and clock rate
* @spi: the device whose settings are being modified
- * Context: can sleep
+ * Context: can sleep, and no requests are queued to the device
*
* SPI protocol drivers may need to update the transfer mode if the
- * device doesn't work with the mode 0 default. They may likewise need
+ * device doesn't work with its default. They may likewise need
* to update clock rates or word sizes from initial values. This function
* changes those settings, and must be called from a context that can sleep.
- * The changes take effect the next time the device is selected and data
- * is transferred to or from it.
+ * Except for SPI_CS_HIGH, which takes effect immediately, the changes take
+ * effect the next time the device is selected and data is transferred to
+ * or from it. When this function returns, the spi device is deselected.
*
* Note that this call will fail if the protocol driver specifies an option
* that the underlying controller or its driver does not support. For
* 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.
* controller_data goes to spi_device.controller_data,
* irq is copied too
*/
- char modalias[KOBJ_NAME_LEN];
+ char modalias[32];
const void *platform_data;
void *controller_data;
int irq;
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