2 * Copyright (C) 2005 David Brownell
4 * This program is free software; you can redistribute it and/or modify
5 * it under the terms of the GNU General Public License as published by
6 * the Free Software Foundation; either version 2 of the License, or
7 * (at your option) any later version.
9 * This program is distributed in the hope that it will be useful,
10 * but WITHOUT ANY WARRANTY; without even the implied warranty of
11 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
12 * GNU General Public License for more details.
14 * You should have received a copy of the GNU General Public License
15 * along with this program; if not, write to the Free Software
16 * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
23 * INTERFACES between SPI master-side drivers and SPI infrastructure.
24 * (There's no SPI slave support for Linux yet...)
26 extern struct bus_type spi_bus_type
;
29 * struct spi_device - Master side proxy for an SPI slave device
30 * @dev: Driver model representation of the device.
31 * @master: SPI controller used with the device.
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.
34 * @chip-select: Chipselect, distinguishing chips handled by "master".
35 * @mode: The spi mode defines how data is clocked out and in.
36 * This may be changed by the device's driver.
37 * @bits_per_word: Data transfers involve one or more words; word sizes
38 * like eight or 12 bits are common. In-memory wordsizes are
39 * powers of two bytes (e.g. 20 bit samples use 32 bits).
40 * This may be changed by the device's driver.
41 * @irq: Negative, or the number passed to request_irq() to receive
42 * interrupts from this device.
43 * @controller_state: Controller's runtime state
44 * @controller_data: Board-specific definitions for controller, such as
45 * FIFO initialization parameters; from board_info.controller_data
47 * An spi_device is used to interchange data between an SPI slave
48 * (usually a discrete chip) and CPU memory.
50 * In "dev", the platform_data is used to hold information about this
51 * device that's meaningful to the device's protocol driver, but not
52 * to its controller. One example might be an identifier for a chip
53 * variant with slightly different functionality.
57 struct spi_master
*master
;
61 #define SPI_CPHA 0x01 /* clock phase */
62 #define SPI_CPOL 0x02 /* clock polarity */
63 #define SPI_MODE_0 (0|0) /* (original MicroWire) */
64 #define SPI_MODE_1 (0|SPI_CPHA)
65 #define SPI_MODE_2 (SPI_CPOL|0)
66 #define SPI_MODE_3 (SPI_CPOL|SPI_CPHA)
67 #define SPI_CS_HIGH 0x04 /* chipselect active high? */
70 void *controller_state
;
71 void *controller_data
;
74 // likely need more hooks for more protocol options affecting how
75 // the controller talks to each chip, like:
76 // - bit order (default is wordwise msb-first)
77 // - memory packing (12 bit samples into low bits, others zeroed)
79 // - drop chipselect after each word
80 // - chipselect delays
84 static inline struct spi_device
*to_spi_device(struct device
*dev
)
86 return dev
? container_of(dev
, struct spi_device
, dev
) : NULL
;
89 /* most drivers won't need to care about device refcounting */
90 static inline struct spi_device
*spi_dev_get(struct spi_device
*spi
)
92 return (spi
&& get_device(&spi
->dev
)) ? spi
: NULL
;
95 static inline void spi_dev_put(struct spi_device
*spi
)
98 put_device(&spi
->dev
);
101 /* ctldata is for the bus_master driver's runtime state */
102 static inline void *spi_get_ctldata(struct spi_device
*spi
)
104 return spi
->controller_state
;
107 static inline void spi_set_ctldata(struct spi_device
*spi
, void *state
)
109 spi
->controller_state
= state
;
118 int (*probe
)(struct spi_device
*spi
);
119 int (*remove
)(struct spi_device
*spi
);
120 void (*shutdown
)(struct spi_device
*spi
);
121 int (*suspend
)(struct spi_device
*spi
, pm_message_t mesg
);
122 int (*resume
)(struct spi_device
*spi
);
123 struct device_driver driver
;
126 static inline struct spi_driver
*to_spi_driver(struct device_driver
*drv
)
128 return drv
? container_of(drv
, struct spi_driver
, driver
) : NULL
;
131 extern int spi_register_driver(struct spi_driver
*sdrv
);
133 static inline void spi_unregister_driver(struct spi_driver
*sdrv
)
137 driver_unregister(&sdrv
->driver
);
143 * struct spi_master - interface to SPI master controller
144 * @cdev: class interface to this driver
145 * @bus_num: board-specific (and often SOC-specific) identifier for a
146 * given SPI controller.
147 * @num_chipselect: chipselects are used to distinguish individual
148 * SPI slaves, and are numbered from zero to num_chipselects.
149 * each slave has a chipselect signal, but it's common that not
150 * every chipselect is connected to a slave.
151 * @setup: updates the device mode and clocking records used by a
152 * device's SPI controller; protocol code may call this.
153 * @transfer: adds a message to the controller's transfer queue.
154 * @cleanup: frees controller-specific state
156 * Each SPI master controller can communicate with one or more spi_device
157 * children. These make a small bus, sharing MOSI, MISO and SCK signals
158 * but not chip select signals. Each device may be configured to use a
159 * different clock rate, since those shared signals are ignored unless
160 * the chip is selected.
162 * The driver for an SPI controller manages access to those devices through
163 * a queue of spi_message transactions, copyin data between CPU memory and
164 * an SPI slave device). For each such message it queues, it calls the
165 * message's completion function when the transaction completes.
168 struct class_device cdev
;
170 /* other than zero (== assign one dynamically), bus_num is fully
171 * board-specific. usually that simplifies to being SOC-specific.
172 * example: one SOC has three SPI controllers, numbered 1..3,
173 * and one board's schematics might show it using SPI-2. software
174 * would normally use bus_num=2 for that controller.
178 /* chipselects will be integral to many controllers; some others
179 * might use board-specific GPIOs.
183 /* setup mode and clock, etc (spi driver may call many times) */
184 int (*setup
)(struct spi_device
*spi
);
186 /* bidirectional bulk transfers
188 * + The transfer() method may not sleep; its main role is
189 * just to add the message to the queue.
190 * + For now there's no remove-from-queue operation, or
191 * any other request management
192 * + To a given spi_device, message queueing is pure fifo
194 * + The master's main job is to process its message queue,
195 * selecting a chip then transferring data
196 * + If there are multiple spi_device children, the i/o queue
197 * arbitration algorithm is unspecified (round robin, fifo,
198 * priority, reservations, preemption, etc)
200 * + Chipselect stays active during the entire message
201 * (unless modified by spi_transfer.cs_change != 0).
202 * + The message transfers use clock and SPI mode parameters
203 * previously established by setup() for this device
205 int (*transfer
)(struct spi_device
*spi
,
206 struct spi_message
*mesg
);
208 /* called on release() to free memory provided by spi_master */
209 void (*cleanup
)(const struct spi_device
*spi
);
212 static inline void *spi_master_get_devdata(struct spi_master
*master
)
214 return class_get_devdata(&master
->cdev
);
217 static inline void spi_master_set_devdata(struct spi_master
*master
, void *data
)
219 class_set_devdata(&master
->cdev
, data
);
222 static inline struct spi_master
*spi_master_get(struct spi_master
*master
)
224 if (!master
|| !class_device_get(&master
->cdev
))
229 static inline void spi_master_put(struct spi_master
*master
)
232 class_device_put(&master
->cdev
);
236 /* the spi driver core manages memory for the spi_master classdev */
237 extern struct spi_master
*
238 spi_alloc_master(struct device
*host
, unsigned size
);
240 extern int spi_register_master(struct spi_master
*master
);
241 extern void spi_unregister_master(struct spi_master
*master
);
243 extern struct spi_master
*spi_busnum_to_master(u16 busnum
);
245 /*---------------------------------------------------------------------------*/
248 * I/O INTERFACE between SPI controller and protocol drivers
250 * Protocol drivers use a queue of spi_messages, each transferring data
251 * between the controller and memory buffers.
253 * The spi_messages themselves consist of a series of read+write transfer
254 * segments. Those segments always read the same number of bits as they
255 * write; but one or the other is easily ignored by passing a null buffer
256 * pointer. (This is unlike most types of I/O API, because SPI hardware
259 * NOTE: Allocation of spi_transfer and spi_message memory is entirely
260 * up to the protocol driver, which guarantees the integrity of both (as
261 * well as the data buffers) for as long as the message is queued.
265 * struct spi_transfer - a read/write buffer pair
266 * @tx_buf: data to be written (dma-safe address), or NULL
267 * @rx_buf: data to be read (dma-safe address), or NULL
268 * @tx_dma: DMA address of buffer, if spi_message.is_dma_mapped
269 * @rx_dma: DMA address of buffer, if spi_message.is_dma_mapped
270 * @len: size of rx and tx buffers (in bytes)
271 * @cs_change: affects chipselect after this transfer completes
272 * @delay_usecs: microseconds to delay after this transfer before
273 * (optionally) changing the chipselect status, then starting
274 * the next transfer or completing this spi_message.
276 * SPI transfers always write the same number of bytes as they read.
277 * Protocol drivers should always provide rx_buf and/or tx_buf.
278 * In some cases, they may also want to provide DMA addresses for
279 * the data being transferred; that may reduce overhead, when the
280 * underlying driver uses dma.
282 * All SPI transfers start with the relevant chipselect active. Drivers
283 * can change behavior of the chipselect after the transfer finishes
284 * (including any mandatory delay). The normal behavior is to leave it
285 * selected, except for the last transfer in a message. Setting cs_change
286 * allows two additional behavior options:
288 * (i) If the transfer isn't the last one in the message, this flag is
289 * used to make the chipselect briefly go inactive in the middle of the
290 * message. Toggling chipselect in this way may be needed to terminate
291 * a chip command, letting a single spi_message perform all of group of
292 * chip transactions together.
294 * (ii) When the transfer is the last one in the message, the chip may
295 * stay selected until the next transfer. This is purely a performance
296 * hint; the controller driver may need to select a different device
297 * for the next message.
299 * The code that submits an spi_message (and its spi_transfers)
300 * to the lower layers is responsible for managing its memory.
301 * Zero-initialize every field you don't set up explicitly, to
302 * insulate against future API updates.
304 struct spi_transfer
{
305 /* it's ok if tx_buf == rx_buf (right?)
306 * for MicroWire, one buffer must be null
307 * buffers must work with dma_*map_single() calls, unless
308 * spi_message.is_dma_mapped reports a pre-existing mapping
317 unsigned cs_change
:1;
322 * struct spi_message - one multi-segment SPI transaction
323 * @transfers: the segements of the transaction
324 * @n_transfer: how many segments
325 * @spi: SPI device to which the transaction is queued
326 * @is_dma_mapped: if true, the caller provided both dma and cpu virtual
327 * addresses for each transfer buffer
328 * @complete: called to report transaction completions
329 * @context: the argument to complete() when it's called
330 * @actual_length: the total number of bytes that were transferred in all
331 * successful segments
332 * @status: zero for success, else negative errno
333 * @queue: for use by whichever driver currently owns the message
334 * @state: for use by whichever driver currently owns the message
336 * The code that submits an spi_message (and its spi_transfers)
337 * to the lower layers is responsible for managing its memory.
338 * Zero-initialize every field you don't set up explicitly, to
339 * insulate against future API updates.
342 struct spi_transfer
*transfers
;
345 struct spi_device
*spi
;
347 unsigned is_dma_mapped
:1;
349 /* REVISIT: we might want a flag affecting the behavior of the
350 * last transfer ... allowing things like "read 16 bit length L"
351 * immediately followed by "read L bytes". Basically imposing
352 * a specific message scheduling algorithm.
354 * Some controller drivers (message-at-a-time queue processing)
355 * could provide that as their default scheduling algorithm. But
356 * others (with multi-message pipelines) could need a flag to
357 * tell them about such special cases.
360 /* completion is reported through a callback */
361 void FASTCALL((*complete
)(void *context
));
363 unsigned actual_length
;
366 /* for optional use by whatever driver currently owns the
367 * spi_message ... between calls to spi_async and then later
368 * complete(), that's the spi_master controller driver.
370 struct list_head queue
;
374 /* It's fine to embed message and transaction structures in other data
375 * structures so long as you don't free them while they're in use.
378 static inline struct spi_message
*spi_message_alloc(unsigned ntrans
, gfp_t flags
)
380 struct spi_message
*m
;
382 m
= kzalloc(sizeof(struct spi_message
)
383 + ntrans
* sizeof(struct spi_transfer
),
386 m
->transfers
= (void *)(m
+ 1);
387 m
->n_transfer
= ntrans
;
392 static inline void spi_message_free(struct spi_message
*m
)
398 * spi_setup -- setup SPI mode and clock rate
399 * @spi: the device whose settings are being modified
401 * SPI protocol drivers may need to update the transfer mode if the
402 * device doesn't work with the mode 0 default. They may likewise need
403 * to update clock rates or word sizes from initial values. This function
404 * changes those settings, and must be called from a context that can sleep.
407 spi_setup(struct spi_device
*spi
)
409 return spi
->master
->setup(spi
);
414 * spi_async -- asynchronous SPI transfer
415 * @spi: device with which data will be exchanged
416 * @message: describes the data transfers, including completion callback
418 * This call may be used in_irq and other contexts which can't sleep,
419 * as well as from task contexts which can sleep.
421 * The completion callback is invoked in a context which can't sleep.
422 * Before that invocation, the value of message->status is undefined.
423 * When the callback is issued, message->status holds either zero (to
424 * indicate complete success) or a negative error code. After that
425 * callback returns, the driver which issued the transfer request may
426 * deallocate the associated memory; it's no longer in use by any SPI
427 * core or controller driver code.
429 * Note that although all messages to a spi_device are handled in
430 * FIFO order, messages may go to different devices in other orders.
431 * Some device might be higher priority, or have various "hard" access
432 * time requirements, for example.
434 * On detection of any fault during the transfer, processing of
435 * the entire message is aborted, and the device is deselected.
436 * Until returning from the associated message completion callback,
437 * no other spi_message queued to that device will be processed.
438 * (This rule applies equally to all the synchronous transfer calls,
439 * which are wrappers around this core asynchronous primitive.)
442 spi_async(struct spi_device
*spi
, struct spi_message
*message
)
445 return spi
->master
->transfer(spi
, message
);
448 /*---------------------------------------------------------------------------*/
450 /* All these synchronous SPI transfer routines are utilities layered
451 * over the core async transfer primitive. Here, "synchronous" means
452 * they will sleep uninterruptibly until the async transfer completes.
455 extern int spi_sync(struct spi_device
*spi
, struct spi_message
*message
);
458 * spi_write - SPI synchronous write
459 * @spi: device to which data will be written
461 * @len: data buffer size
463 * This writes the buffer and returns zero or a negative error code.
464 * Callable only from contexts that can sleep.
467 spi_write(struct spi_device
*spi
, const u8
*buf
, size_t len
)
469 struct spi_transfer t
= {
475 struct spi_message m
= {
480 return spi_sync(spi
, &m
);
484 * spi_read - SPI synchronous read
485 * @spi: device from which data will be read
487 * @len: data buffer size
489 * This writes the buffer and returns zero or a negative error code.
490 * Callable only from contexts that can sleep.
493 spi_read(struct spi_device
*spi
, u8
*buf
, size_t len
)
495 struct spi_transfer t
= {
501 struct spi_message m
= {
506 return spi_sync(spi
, &m
);
509 /* this copies txbuf and rxbuf data; for small transfers only! */
510 extern int spi_write_then_read(struct spi_device
*spi
,
511 const u8
*txbuf
, unsigned n_tx
,
512 u8
*rxbuf
, unsigned n_rx
);
515 * spi_w8r8 - SPI synchronous 8 bit write followed by 8 bit read
516 * @spi: device with which data will be exchanged
517 * @cmd: command to be written before data is read back
519 * This returns the (unsigned) eight bit number returned by the
520 * device, or else a negative error code. Callable only from
521 * contexts that can sleep.
523 static inline ssize_t
spi_w8r8(struct spi_device
*spi
, u8 cmd
)
528 status
= spi_write_then_read(spi
, &cmd
, 1, &result
, 1);
530 /* return negative errno or unsigned value */
531 return (status
< 0) ? status
: result
;
535 * spi_w8r16 - SPI synchronous 8 bit write followed by 16 bit read
536 * @spi: device with which data will be exchanged
537 * @cmd: command to be written before data is read back
539 * This returns the (unsigned) sixteen bit number returned by the
540 * device, or else a negative error code. Callable only from
541 * contexts that can sleep.
543 * The number is returned in wire-order, which is at least sometimes
546 static inline ssize_t
spi_w8r16(struct spi_device
*spi
, u8 cmd
)
551 status
= spi_write_then_read(spi
, &cmd
, 1, (u8
*) &result
, 2);
553 /* return negative errno or unsigned value */
554 return (status
< 0) ? status
: result
;
557 /*---------------------------------------------------------------------------*/
560 * INTERFACE between board init code and SPI infrastructure.
562 * No SPI driver ever sees these SPI device table segments, but
563 * it's how the SPI core (or adapters that get hotplugged) grows
564 * the driver model tree.
566 * As a rule, SPI devices can't be probed. Instead, board init code
567 * provides a table listing the devices which are present, with enough
568 * information to bind and set up the device's driver. There's basic
569 * support for nonstatic configurations too; enough to handle adding
570 * parport adapters, or microcontrollers acting as USB-to-SPI bridges.
573 /* board-specific information about each SPI device */
574 struct spi_board_info
{
575 /* the device name and module name are coupled, like platform_bus;
576 * "modalias" is normally the driver name.
578 * platform_data goes to spi_device.dev.platform_data,
579 * controller_data goes to spi_device.controller_data,
582 char modalias
[KOBJ_NAME_LEN
];
583 const void *platform_data
;
584 void *controller_data
;
587 /* slower signaling on noisy or low voltage boards */
591 /* bus_num is board specific and matches the bus_num of some
592 * spi_master that will probably be registered later.
594 * chip_select reflects how this chip is wired to that master;
595 * it's less than num_chipselect.
600 /* ... may need additional spi_device chip config data here.
601 * avoid stuff protocol drivers can set; but include stuff
602 * needed to behave without being bound to a driver:
603 * - chipselect polarity
604 * - quirks like clock rate mattering when not selected
610 spi_register_board_info(struct spi_board_info
const *info
, unsigned n
);
612 /* board init code may ignore whether SPI is configured or not */
614 spi_register_board_info(struct spi_board_info
const *info
, unsigned n
)
619 /* If you're hotplugging an adapter with devices (parport, usb, etc)
620 * use spi_new_device() to describe each device. You can also call
621 * spi_unregister_device() to start making that device vanish, but
622 * normally that would be handled by spi_unregister_master().
624 extern struct spi_device
*
625 spi_new_device(struct spi_master
*, struct spi_board_info
*);
628 spi_unregister_device(struct spi_device
*spi
)
631 device_unregister(&spi
->dev
);
634 #endif /* __LINUX_SPI_H */