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-rw-r--r--include/linux/spi/spi.h82
1 files changed, 51 insertions, 31 deletions
diff --git a/include/linux/spi/spi.h b/include/linux/spi/spi.h
index 4f0f8c2e58a5..b6bedc3ee95c 100644
--- a/include/linux/spi/spi.h
+++ b/include/linux/spi/spi.h
@@ -32,11 +32,12 @@ extern struct bus_type spi_bus_type;
32 * @max_speed_hz: Maximum clock rate to be used with this chip 32 * @max_speed_hz: Maximum clock rate to be used with this chip
33 * (on this board); may be changed by the device's driver. 33 * (on this board); may be changed by the device's driver.
34 * The spi_transfer.speed_hz can override this for each transfer. 34 * The spi_transfer.speed_hz can override this for each transfer.
35 * @chip-select: Chipselect, distinguishing chips handled by "master". 35 * @chip_select: Chipselect, distinguishing chips handled by @master.
36 * @mode: The spi mode defines how data is clocked out and in. 36 * @mode: The spi mode defines how data is clocked out and in.
37 * This may be changed by the device's driver. 37 * This may be changed by the device's driver.
38 * The "active low" default for chipselect mode can be overridden, 38 * The "active low" default for chipselect mode can be overridden
39 * as can the "MSB first" default for each word in a transfer. 39 * (by specifying SPI_CS_HIGH) as can the "MSB first" default for
40 * each word in a transfer (by specifying SPI_LSB_FIRST).
40 * @bits_per_word: Data transfers involve one or more words; word sizes 41 * @bits_per_word: Data transfers involve one or more words; word sizes
41 * like eight or 12 bits are common. In-memory wordsizes are 42 * like eight or 12 bits are common. In-memory wordsizes are
42 * powers of two bytes (e.g. 20 bit samples use 32 bits). 43 * powers of two bytes (e.g. 20 bit samples use 32 bits).
@@ -48,14 +49,18 @@ extern struct bus_type spi_bus_type;
48 * @controller_state: Controller's runtime state 49 * @controller_state: Controller's runtime state
49 * @controller_data: Board-specific definitions for controller, such as 50 * @controller_data: Board-specific definitions for controller, such as
50 * FIFO initialization parameters; from board_info.controller_data 51 * FIFO initialization parameters; from board_info.controller_data
52 * @modalias: Name of the driver to use with this device, or an alias
53 * for that name. This appears in the sysfs "modalias" attribute
54 * for driver coldplugging, and in uevents used for hotplugging
51 * 55 *
52 * An spi_device is used to interchange data between an SPI slave 56 * A @spi_device is used to interchange data between an SPI slave
53 * (usually a discrete chip) and CPU memory. 57 * (usually a discrete chip) and CPU memory.
54 * 58 *
55 * In "dev", the platform_data is used to hold information about this 59 * In @dev, the platform_data is used to hold information about this
56 * device that's meaningful to the device's protocol driver, but not 60 * device that's meaningful to the device's protocol driver, but not
57 * to its controller. One example might be an identifier for a chip 61 * to its controller. One example might be an identifier for a chip
58 * variant with slightly different functionality. 62 * variant with slightly different functionality; another might be
63 * information about how this particular board wires the chip's pins.
59 */ 64 */
60struct spi_device { 65struct spi_device {
61 struct device dev; 66 struct device dev;
@@ -77,13 +82,15 @@ struct spi_device {
77 void *controller_data; 82 void *controller_data;
78 const char *modalias; 83 const char *modalias;
79 84
80 // likely need more hooks for more protocol options affecting how 85 /*
81 // the controller talks to each chip, like: 86 * likely need more hooks for more protocol options affecting how
82 // - memory packing (12 bit samples into low bits, others zeroed) 87 * the controller talks to each chip, like:
83 // - priority 88 * - memory packing (12 bit samples into low bits, others zeroed)
84 // - drop chipselect after each word 89 * - priority
85 // - chipselect delays 90 * - drop chipselect after each word
86 // - ... 91 * - chipselect delays
92 * - ...
93 */
87}; 94};
88 95
89static inline struct spi_device *to_spi_device(struct device *dev) 96static inline struct spi_device *to_spi_device(struct device *dev)
@@ -146,6 +153,11 @@ static inline struct spi_driver *to_spi_driver(struct device_driver *drv)
146 153
147extern int spi_register_driver(struct spi_driver *sdrv); 154extern int spi_register_driver(struct spi_driver *sdrv);
148 155
156/**
157 * spi_unregister_driver - reverse effect of spi_register_driver
158 * @sdrv: the driver to unregister
159 * Context: can sleep
160 */
149static inline void spi_unregister_driver(struct spi_driver *sdrv) 161static inline void spi_unregister_driver(struct spi_driver *sdrv)
150{ 162{
151 if (sdrv) 163 if (sdrv)
@@ -165,18 +177,20 @@ static inline void spi_unregister_driver(struct spi_driver *sdrv)
165 * @setup: updates the device mode and clocking records used by a 177 * @setup: updates the device mode and clocking records used by a
166 * device's SPI controller; protocol code may call this. This 178 * device's SPI controller; protocol code may call this. This
167 * must fail if an unrecognized or unsupported mode is requested. 179 * must fail if an unrecognized or unsupported mode is requested.
180 * It's always safe to call this unless transfers are pending on
181 * the device whose settings are being modified.
168 * @transfer: adds a message to the controller's transfer queue. 182 * @transfer: adds a message to the controller's transfer queue.
169 * @cleanup: frees controller-specific state 183 * @cleanup: frees controller-specific state
170 * 184 *
171 * Each SPI master controller can communicate with one or more spi_device 185 * Each SPI master controller can communicate with one or more @spi_device
172 * children. These make a small bus, sharing MOSI, MISO and SCK signals 186 * children. These make a small bus, sharing MOSI, MISO and SCK signals
173 * but not chip select signals. Each device may be configured to use a 187 * but not chip select signals. Each device may be configured to use a
174 * different clock rate, since those shared signals are ignored unless 188 * different clock rate, since those shared signals are ignored unless
175 * the chip is selected. 189 * the chip is selected.
176 * 190 *
177 * The driver for an SPI controller manages access to those devices through 191 * The driver for an SPI controller manages access to those devices through
178 * a queue of spi_message transactions, copyin data between CPU memory and 192 * a queue of spi_message transactions, copying data between CPU memory and
179 * an SPI slave device). For each such message it queues, it calls the 193 * an SPI slave device. For each such message it queues, it calls the
180 * message's completion function when the transaction completes. 194 * message's completion function when the transaction completes.
181 */ 195 */
182struct spi_master { 196struct spi_master {
@@ -280,27 +294,27 @@ extern struct spi_master *spi_busnum_to_master(u16 busnum);
280 * struct spi_transfer - a read/write buffer pair 294 * struct spi_transfer - a read/write buffer pair
281 * @tx_buf: data to be written (dma-safe memory), or NULL 295 * @tx_buf: data to be written (dma-safe memory), or NULL
282 * @rx_buf: data to be read (dma-safe memory), or NULL 296 * @rx_buf: data to be read (dma-safe memory), or NULL
283 * @tx_dma: DMA address of tx_buf, if spi_message.is_dma_mapped 297 * @tx_dma: DMA address of tx_buf, if @spi_message.is_dma_mapped
284 * @rx_dma: DMA address of rx_buf, if spi_message.is_dma_mapped 298 * @rx_dma: DMA address of rx_buf, if @spi_message.is_dma_mapped
285 * @len: size of rx and tx buffers (in bytes) 299 * @len: size of rx and tx buffers (in bytes)
286 * @speed_hz: Select a speed other then the device default for this 300 * @speed_hz: Select a speed other then the device default for this
287 * transfer. If 0 the default (from spi_device) is used. 301 * transfer. If 0 the default (from @spi_device) is used.
288 * @bits_per_word: select a bits_per_word other then the device default 302 * @bits_per_word: select a bits_per_word other then the device default
289 * for this transfer. If 0 the default (from spi_device) is used. 303 * for this transfer. If 0 the default (from @spi_device) is used.
290 * @cs_change: affects chipselect after this transfer completes 304 * @cs_change: affects chipselect after this transfer completes
291 * @delay_usecs: microseconds to delay after this transfer before 305 * @delay_usecs: microseconds to delay after this transfer before
292 * (optionally) changing the chipselect status, then starting 306 * (optionally) changing the chipselect status, then starting
293 * the next transfer or completing this spi_message. 307 * the next transfer or completing this @spi_message.
294 * @transfer_list: transfers are sequenced through spi_message.transfers 308 * @transfer_list: transfers are sequenced through @spi_message.transfers
295 * 309 *
296 * SPI transfers always write the same number of bytes as they read. 310 * SPI transfers always write the same number of bytes as they read.
297 * Protocol drivers should always provide rx_buf and/or tx_buf. 311 * Protocol drivers should always provide @rx_buf and/or @tx_buf.
298 * In some cases, they may also want to provide DMA addresses for 312 * In some cases, they may also want to provide DMA addresses for
299 * the data being transferred; that may reduce overhead, when the 313 * the data being transferred; that may reduce overhead, when the
300 * underlying driver uses dma. 314 * underlying driver uses dma.
301 * 315 *
302 * If the transmit buffer is null, zeroes will be shifted out 316 * If the transmit buffer is null, zeroes will be shifted out
303 * while filling rx_buf. If the receive buffer is null, the data 317 * while filling @rx_buf. If the receive buffer is null, the data
304 * shifted in will be discarded. Only "len" bytes shift out (or in). 318 * shifted in will be discarded. Only "len" bytes shift out (or in).
305 * It's an error to try to shift out a partial word. (For example, by 319 * It's an error to try to shift out a partial word. (For example, by
306 * shifting out three bytes with word size of sixteen or twenty bits; 320 * shifting out three bytes with word size of sixteen or twenty bits;
@@ -309,7 +323,7 @@ extern struct spi_master *spi_busnum_to_master(u16 busnum);
309 * In-memory data values are always in native CPU byte order, translated 323 * In-memory data values are always in native CPU byte order, translated
310 * from the wire byte order (big-endian except with SPI_LSB_FIRST). So 324 * from the wire byte order (big-endian except with SPI_LSB_FIRST). So
311 * for example when bits_per_word is sixteen, buffers are 2N bytes long 325 * for example when bits_per_word is sixteen, buffers are 2N bytes long
312 * and hold N sixteen bit words in CPU byte order. 326 * (@len = 2N) and hold N sixteen bit words in CPU byte order.
313 * 327 *
314 * When the word size of the SPI transfer is not a power-of-two multiple 328 * When the word size of the SPI transfer is not a power-of-two multiple
315 * of eight bits, those in-memory words include extra bits. In-memory 329 * of eight bits, those in-memory words include extra bits. In-memory
@@ -318,7 +332,7 @@ extern struct spi_master *spi_busnum_to_master(u16 busnum);
318 * 332 *
319 * All SPI transfers start with the relevant chipselect active. Normally 333 * All SPI transfers start with the relevant chipselect active. Normally
320 * it stays selected until after the last transfer in a message. Drivers 334 * it stays selected until after the last transfer in a message. Drivers
321 * can affect the chipselect signal using cs_change: 335 * can affect the chipselect signal using cs_change.
322 * 336 *
323 * (i) If the transfer isn't the last one in the message, this flag is 337 * (i) If the transfer isn't the last one in the message, this flag is
324 * used to make the chipselect briefly go inactive in the middle of the 338 * used to make the chipselect briefly go inactive in the middle of the
@@ -372,7 +386,7 @@ struct spi_transfer {
372 * @queue: for use by whichever driver currently owns the message 386 * @queue: for use by whichever driver currently owns the message
373 * @state: for use by whichever driver currently owns the message 387 * @state: for use by whichever driver currently owns the message
374 * 388 *
375 * An spi_message is used to execute an atomic sequence of data transfers, 389 * A @spi_message is used to execute an atomic sequence of data transfers,
376 * each represented by a struct spi_transfer. The sequence is "atomic" 390 * each represented by a struct spi_transfer. The sequence is "atomic"
377 * in the sense that no other spi_message may use that SPI bus until that 391 * in the sense that no other spi_message may use that SPI bus until that
378 * sequence completes. On some systems, many such sequences can execute as 392 * sequence completes. On some systems, many such sequences can execute as
@@ -464,8 +478,9 @@ static inline void spi_message_free(struct spi_message *m)
464} 478}
465 479
466/** 480/**
467 * spi_setup -- setup SPI mode and clock rate 481 * spi_setup - setup SPI mode and clock rate
468 * @spi: the device whose settings are being modified 482 * @spi: the device whose settings are being modified
483 * Context: can sleep
469 * 484 *
470 * SPI protocol drivers may need to update the transfer mode if the 485 * SPI protocol drivers may need to update the transfer mode if the
471 * device doesn't work with the mode 0 default. They may likewise need 486 * device doesn't work with the mode 0 default. They may likewise need
@@ -474,7 +489,7 @@ static inline void spi_message_free(struct spi_message *m)
474 * The changes take effect the next time the device is selected and data 489 * The changes take effect the next time the device is selected and data
475 * is transferred to or from it. 490 * is transferred to or from it.
476 * 491 *
477 * Note that this call wil fail if the protocol driver specifies an option 492 * Note that this call will fail if the protocol driver specifies an option
478 * that the underlying controller or its driver does not support. For 493 * that the underlying controller or its driver does not support. For
479 * example, not all hardware supports wire transfers using nine bit words, 494 * example, not all hardware supports wire transfers using nine bit words,
480 * LSB-first wire encoding, or active-high chipselects. 495 * LSB-first wire encoding, or active-high chipselects.
@@ -487,9 +502,10 @@ spi_setup(struct spi_device *spi)
487 502
488 503
489/** 504/**
490 * spi_async -- asynchronous SPI transfer 505 * spi_async - asynchronous SPI transfer
491 * @spi: device with which data will be exchanged 506 * @spi: device with which data will be exchanged
492 * @message: describes the data transfers, including completion callback 507 * @message: describes the data transfers, including completion callback
508 * Context: any (irqs may be blocked, etc)
493 * 509 *
494 * This call may be used in_irq and other contexts which can't sleep, 510 * This call may be used in_irq and other contexts which can't sleep,
495 * as well as from task contexts which can sleep. 511 * as well as from task contexts which can sleep.
@@ -535,6 +551,7 @@ extern int spi_sync(struct spi_device *spi, struct spi_message *message);
535 * @spi: device to which data will be written 551 * @spi: device to which data will be written
536 * @buf: data buffer 552 * @buf: data buffer
537 * @len: data buffer size 553 * @len: data buffer size
554 * Context: can sleep
538 * 555 *
539 * This writes the buffer and returns zero or a negative error code. 556 * This writes the buffer and returns zero or a negative error code.
540 * Callable only from contexts that can sleep. 557 * Callable only from contexts that can sleep.
@@ -558,8 +575,9 @@ spi_write(struct spi_device *spi, const u8 *buf, size_t len)
558 * @spi: device from which data will be read 575 * @spi: device from which data will be read
559 * @buf: data buffer 576 * @buf: data buffer
560 * @len: data buffer size 577 * @len: data buffer size
578 * Context: can sleep
561 * 579 *
562 * This writes the buffer and returns zero or a negative error code. 580 * This reads the buffer and returns zero or a negative error code.
563 * Callable only from contexts that can sleep. 581 * Callable only from contexts that can sleep.
564 */ 582 */
565static inline int 583static inline int
@@ -585,6 +603,7 @@ extern int spi_write_then_read(struct spi_device *spi,
585 * spi_w8r8 - SPI synchronous 8 bit write followed by 8 bit read 603 * spi_w8r8 - SPI synchronous 8 bit write followed by 8 bit read
586 * @spi: device with which data will be exchanged 604 * @spi: device with which data will be exchanged
587 * @cmd: command to be written before data is read back 605 * @cmd: command to be written before data is read back
606 * Context: can sleep
588 * 607 *
589 * This returns the (unsigned) eight bit number returned by the 608 * This returns the (unsigned) eight bit number returned by the
590 * device, or else a negative error code. Callable only from 609 * device, or else a negative error code. Callable only from
@@ -605,6 +624,7 @@ static inline ssize_t spi_w8r8(struct spi_device *spi, u8 cmd)
605 * spi_w8r16 - SPI synchronous 8 bit write followed by 16 bit read 624 * spi_w8r16 - SPI synchronous 8 bit write followed by 16 bit read
606 * @spi: device with which data will be exchanged 625 * @spi: device with which data will be exchanged
607 * @cmd: command to be written before data is read back 626 * @cmd: command to be written before data is read back
627 * Context: can sleep
608 * 628 *
609 * This returns the (unsigned) sixteen bit number returned by the 629 * This returns the (unsigned) sixteen bit number returned by the
610 * device, or else a negative error code. Callable only from 630 * device, or else a negative error code. Callable only from