#ifndef __LINUX_SPI_H
#define __LINUX_SPI_H
+#include <linux/device.h>
+
/*
* INTERFACES between SPI master-side drivers and SPI infrastructure.
* (There's no SPI slave support for Linux yet...)
* @max_speed_hz: Maximum clock rate to be used with this chip
* (on this board); may be changed by the device's driver.
* The spi_transfer.speed_hz can override this for each transfer.
- * @chip-select: Chipselect, distinguishing chips handled by "master".
+ * @chip_select: Chipselect, distinguishing chips handled by @master.
* @mode: The spi mode defines how data is clocked out and in.
* This may be changed by the device's driver.
- * The "active low" default for chipselect mode can be overridden,
- * as can the "MSB first" default for each word in a transfer.
+ * The "active low" default for chipselect mode can be overridden
+ * (by specifying SPI_CS_HIGH) as can the "MSB first" default for
+ * each word in a transfer (by specifying SPI_LSB_FIRST).
* @bits_per_word: Data transfers involve one or more words; word sizes
* like eight or 12 bits are common. In-memory wordsizes are
* powers of two bytes (e.g. 20 bit samples use 32 bits).
* @controller_state: Controller's runtime state
* @controller_data: Board-specific definitions for controller, such as
* FIFO initialization parameters; from board_info.controller_data
+ * @modalias: Name of the driver to use with this device, or an alias
+ * for that name. This appears in the sysfs "modalias" attribute
+ * for driver coldplugging, and in uevents used for hotplugging
*
- * An spi_device is used to interchange data between an SPI slave
+ * A @spi_device is used to interchange data between an SPI slave
* (usually a discrete chip) and CPU memory.
*
- * In "dev", the platform_data is used to hold information about this
+ * In @dev, the platform_data is used to hold information about this
* device that's meaningful to the device's protocol driver, but not
* to its controller. One example might be an identifier for a chip
- * variant with slightly different functionality.
+ * variant with slightly different functionality; another might be
+ * information about how this particular board wires the chip's pins.
*/
struct spi_device {
struct device dev;
#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;
void *controller_data;
- const char *modalias;
-
- // likely need more hooks for more protocol options affecting how
- // the controller talks to each chip, like:
- // - memory packing (12 bit samples into low bits, others zeroed)
- // - priority
- // - drop chipselect after each word
- // - chipselect delays
- // - ...
+ char modalias[32];
+
+ /*
+ * likely need more hooks for more protocol options affecting how
+ * the controller talks to each chip, like:
+ * - memory packing (12 bit samples into low bits, others zeroed)
+ * - priority
+ * - drop chipselect after each word
+ * - chipselect delays
+ * - ...
+ */
};
static inline struct spi_device *to_spi_device(struct device *dev)
+/**
+ * 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);
extern int spi_register_driver(struct spi_driver *sdrv);
+/**
+ * spi_unregister_driver - reverse effect of spi_register_driver
+ * @sdrv: the driver to unregister
+ * Context: can sleep
+ */
static inline void spi_unregister_driver(struct spi_driver *sdrv)
{
if (sdrv)
/**
* 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
* SPI slaves, and are numbered from zero to num_chipselects.
* each slave has a chipselect signal, but it's common that not
* every chipselect is connected to a slave.
+ * @dma_alignment: SPI controller constraint on DMA buffers alignment.
* @setup: updates the device mode and clocking records used by a
- * device's SPI controller; protocol code may call this.
+ * device's SPI controller; protocol code may call this. This
+ * must fail if an unrecognized or unsupported mode is requested.
+ * It's always safe to call this unless transfers are pending on
+ * the device whose settings are being modified.
* @transfer: adds a message to the controller's transfer queue.
* @cleanup: frees controller-specific state
*
- * Each SPI master controller can communicate with one or more spi_device
+ * Each SPI master controller can communicate with one or more @spi_device
* children. These make a small bus, sharing MOSI, MISO and SCK signals
* but not chip select signals. Each device may be configured to use a
* different clock rate, since those shared signals are ignored unless
* the chip is selected.
*
* The driver for an SPI controller manages access to those devices through
- * a queue of spi_message transactions, copyin data between CPU memory and
- * an SPI slave device). For each such message it queues, it calls the
+ * a queue of spi_message transactions, copying data between CPU memory and
+ * an SPI slave device. For each such message it queues, it calls the
* 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.
*/
u16 num_chipselect;
- /* setup mode and clock, etc (spi driver may call many times) */
+ /* some SPI controllers pose alignment requirements on DMAable
+ * buffers; let protocol drivers know about these requirements.
+ */
+ u16 dma_alignment;
+
+ /* Setup mode and clock, etc (spi driver may call many times).
+ *
+ * IMPORTANT: this may be called when transfers to another
+ * device are active. DO NOT UPDATE SHARED REGISTERS in ways
+ * which could break those transfers.
+ */
int (*setup)(struct spi_device *spi);
/* bidirectional bulk transfers
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);
}
* struct spi_transfer - a read/write buffer pair
* @tx_buf: data to be written (dma-safe memory), or NULL
* @rx_buf: data to be read (dma-safe memory), or NULL
- * @tx_dma: DMA address of tx_buf, if spi_message.is_dma_mapped
- * @rx_dma: DMA address of rx_buf, if spi_message.is_dma_mapped
+ * @tx_dma: DMA address of tx_buf, if @spi_message.is_dma_mapped
+ * @rx_dma: DMA address of rx_buf, if @spi_message.is_dma_mapped
* @len: size of rx and tx buffers (in bytes)
- * @speed_hz: Select a speed other then the device default for this
- * transfer. If 0 the default (from spi_device) is used.
- * @bits_per_word: select a bits_per_word other then the device default
- * for this transfer. If 0 the default (from spi_device) is used.
+ * @speed_hz: Select a speed other than the device default for this
+ * transfer. If 0 the default (from @spi_device) is used.
+ * @bits_per_word: select a bits_per_word other than the device default
+ * for this transfer. If 0 the default (from @spi_device) is used.
* @cs_change: affects chipselect after this transfer completes
* @delay_usecs: microseconds to delay after this transfer before
* (optionally) changing the chipselect status, then starting
- * the next transfer or completing this spi_message.
- * @transfer_list: transfers are sequenced through spi_message.transfers
+ * the next transfer or completing this @spi_message.
+ * @transfer_list: transfers are sequenced through @spi_message.transfers
*
* SPI transfers always write the same number of bytes as they read.
- * Protocol drivers should always provide rx_buf and/or tx_buf.
+ * Protocol drivers should always provide @rx_buf and/or @tx_buf.
* In some cases, they may also want to provide DMA addresses for
* the data being transferred; that may reduce overhead, when the
* underlying driver uses dma.
*
* If the transmit buffer is null, zeroes will be shifted out
- * while filling rx_buf. If the receive buffer is null, the data
+ * while filling @rx_buf. If the receive buffer is null, the data
* shifted in will be discarded. Only "len" bytes shift out (or in).
* It's an error to try to shift out a partial word. (For example, by
* shifting out three bytes with word size of sixteen or twenty bits;
* the former uses two bytes per word, the latter uses four bytes.)
*
+ * In-memory data values are always in native CPU byte order, translated
+ * from the wire byte order (big-endian except with SPI_LSB_FIRST). So
+ * for example when bits_per_word is sixteen, buffers are 2N bytes long
+ * (@len = 2N) and hold N sixteen bit words in CPU byte order.
+ *
+ * When the word size of the SPI transfer is not a power-of-two multiple
+ * of eight bits, those in-memory words include extra bits. In-memory
+ * words are always seen by protocol drivers as right-justified, so the
+ * undefined (rx) or unused (tx) bits are always the most significant bits.
+ *
* All SPI transfers start with the relevant chipselect active. Normally
* it stays selected until after the last transfer in a message. Drivers
- * can affect the chipselect signal using cs_change:
+ * can affect the chipselect signal using cs_change.
*
* (i) If the transfer isn't the last one in the message, this flag is
* used to make the chipselect briefly go inactive in the middle of the
* 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.
* @queue: for use by whichever driver currently owns the message
* @state: for use by whichever driver currently owns the message
*
- * An spi_message is used to execute an atomic sequence of data transfers,
+ * A @spi_message is used to execute an atomic sequence of data transfers,
* each represented by a struct spi_transfer. The sequence is "atomic"
* in the sense that no other spi_message may use that SPI bus until that
* sequence completes. On some systems, many such sequences can execute as
}
/**
- * spi_setup -- setup SPI mode and clock rate
+ * spi_setup - setup SPI mode and clock rate
* @spi: the device whose settings are being modified
+ * 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
+ * example, not all hardware supports wire transfers using nine bit words,
+ * LSB-first wire encoding, or active-high chipselects.
*/
static inline int
spi_setup(struct spi_device *spi)
/**
- * spi_async -- asynchronous SPI transfer
+ * spi_async - asynchronous SPI transfer
* @spi: device with which data will be exchanged
* @message: describes the data transfers, including completion callback
+ * Context: any (irqs may be blocked, etc)
*
* This call may be used in_irq and other contexts which can't sleep,
* as well as from task contexts which can sleep.
* @spi: device to which data will be written
* @buf: data buffer
* @len: data buffer size
+ * Context: can sleep
*
* This writes the buffer and returns zero or a negative error code.
* Callable only from contexts that can sleep.
* @spi: device from which data will be read
* @buf: data buffer
* @len: data buffer size
+ * Context: can sleep
*
- * This writes the buffer and returns zero or a negative error code.
+ * This reads the buffer and returns zero or a negative error code.
* Callable only from contexts that can sleep.
*/
static inline int
* spi_w8r8 - SPI synchronous 8 bit write followed by 8 bit read
* @spi: device with which data will be exchanged
* @cmd: command to be written before data is read back
+ * Context: can sleep
*
* This returns the (unsigned) eight bit number returned by the
* device, or else a negative error code. Callable only from
* spi_w8r16 - SPI synchronous 8 bit write followed by 16 bit read
* @spi: device with which data will be exchanged
* @cmd: command to be written before data is read back
+ * Context: can sleep
*
* This returns the (unsigned) sixteen bit number returned by the
* device, or else a negative error code. Callable only from
* 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;
* use spi_new_device() to describe each device. You can also call
* spi_unregister_device() to start making that device vanish, but
* normally that would be handled by spi_unregister_master().
+ *
+ * You can also use spi_alloc_device() and spi_add_device() to use a two
+ * stage registration sequence for each spi_device. This gives the caller
+ * some more control over the spi_device structure before it is registered,
+ * but requires that caller to initialize fields that would otherwise
+ * be defined using the board info.
*/
extern struct spi_device *
+spi_alloc_device(struct spi_master *master);
+
+extern int
+spi_add_device(struct spi_device *spi);
+
+extern struct spi_device *
spi_new_device(struct spi_master *, struct spi_board_info *);
static inline void
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