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 * The spi_transfer.speed_hz can override this for each transfer.
35 * @chip-select: Chipselect, distinguishing chips handled by "master".
36 * @mode: The spi mode defines how data is clocked out and in.
37 * This may be changed by the device's driver.
38 * @bits_per_word: Data transfers involve one or more words; word sizes
39 * like eight or 12 bits are common. In-memory wordsizes are
40 * powers of two bytes (e.g. 20 bit samples use 32 bits).
41 * This may be changed by the device's driver.
42 * The spi_transfer.bits_per_word can override this for each transfer.
43 * @irq: Negative, or the number passed to request_irq() to receive
44 * interrupts from this device.
45 * @controller_state: Controller's runtime state
46 * @controller_data: Board-specific definitions for controller, such as
47 * FIFO initialization parameters; from board_info.controller_data
49 * An spi_device is used to interchange data between an SPI slave
50 * (usually a discrete chip) and CPU memory.
52 * In "dev", the platform_data is used to hold information about this
53 * device that's meaningful to the device's protocol driver, but not
54 * to its controller. One example might be an identifier for a chip
55 * variant with slightly different functionality.
59 struct spi_master *master;
63 #define SPI_CPHA 0x01 /* clock phase */
64 #define SPI_CPOL 0x02 /* clock polarity */
65 #define SPI_MODE_0 (0|0) /* (original MicroWire) */
66 #define SPI_MODE_1 (0|SPI_CPHA)
67 #define SPI_MODE_2 (SPI_CPOL|0)
68 #define SPI_MODE_3 (SPI_CPOL|SPI_CPHA)
69 #define SPI_CS_HIGH 0x04 /* chipselect active high? */
72 void *controller_state;
73 void *controller_data;
76 // likely need more hooks for more protocol options affecting how
77 // the controller talks to each chip, like:
78 // - bit order (default is wordwise msb-first)
79 // - memory packing (12 bit samples into low bits, others zeroed)
81 // - drop chipselect after each word
82 // - chipselect delays
86 static inline struct spi_device *to_spi_device(struct device *dev)
88 return dev ? container_of(dev, struct spi_device, dev) : NULL;
91 /* most drivers won't need to care about device refcounting */
92 static inline struct spi_device *spi_dev_get(struct spi_device *spi)
94 return (spi && get_device(&spi->dev)) ? spi : NULL;
97 static inline void spi_dev_put(struct spi_device *spi)
100 put_device(&spi->dev);
103 /* ctldata is for the bus_master driver's runtime state */
104 static inline void *spi_get_ctldata(struct spi_device *spi)
106 return spi->controller_state;
109 static inline void spi_set_ctldata(struct spi_device *spi, void *state)
111 spi->controller_state = state;
120 int (*probe)(struct spi_device *spi);
121 int (*remove)(struct spi_device *spi);
122 void (*shutdown)(struct spi_device *spi);
123 int (*suspend)(struct spi_device *spi, pm_message_t mesg);
124 int (*resume)(struct spi_device *spi);
125 struct device_driver driver;
128 static inline struct spi_driver *to_spi_driver(struct device_driver *drv)
130 return drv ? container_of(drv, struct spi_driver, driver) : NULL;
133 extern int spi_register_driver(struct spi_driver *sdrv);
135 static inline void spi_unregister_driver(struct spi_driver *sdrv)
139 driver_unregister(&sdrv->driver);
145 * struct spi_master - interface to SPI master controller
146 * @cdev: class interface to this driver
147 * @bus_num: board-specific (and often SOC-specific) identifier for a
148 * given SPI controller.
149 * @num_chipselect: chipselects are used to distinguish individual
150 * SPI slaves, and are numbered from zero to num_chipselects.
151 * each slave has a chipselect signal, but it's common that not
152 * every chipselect is connected to a slave.
153 * @setup: updates the device mode and clocking records used by a
154 * device's SPI controller; protocol code may call this.
155 * @transfer: adds a message to the controller's transfer queue.
156 * @cleanup: frees controller-specific state
158 * Each SPI master controller can communicate with one or more spi_device
159 * children. These make a small bus, sharing MOSI, MISO and SCK signals
160 * but not chip select signals. Each device may be configured to use a
161 * different clock rate, since those shared signals are ignored unless
162 * the chip is selected.
164 * The driver for an SPI controller manages access to those devices through
165 * a queue of spi_message transactions, copyin data between CPU memory and
166 * an SPI slave device). For each such message it queues, it calls the
167 * message's completion function when the transaction completes.
170 struct class_device cdev;
172 /* other than zero (== assign one dynamically), bus_num is fully
173 * board-specific. usually that simplifies to being SOC-specific.
174 * example: one SOC has three SPI controllers, numbered 1..3,
175 * and one board's schematics might show it using SPI-2. software
176 * would normally use bus_num=2 for that controller.
180 /* chipselects will be integral to many controllers; some others
181 * might use board-specific GPIOs.
185 /* setup mode and clock, etc (spi driver may call many times) */
186 int (*setup)(struct spi_device *spi);
188 /* bidirectional bulk transfers
190 * + The transfer() method may not sleep; its main role is
191 * just to add the message to the queue.
192 * + For now there's no remove-from-queue operation, or
193 * any other request management
194 * + To a given spi_device, message queueing is pure fifo
196 * + The master's main job is to process its message queue,
197 * selecting a chip then transferring data
198 * + If there are multiple spi_device children, the i/o queue
199 * arbitration algorithm is unspecified (round robin, fifo,
200 * priority, reservations, preemption, etc)
202 * + Chipselect stays active during the entire message
203 * (unless modified by spi_transfer.cs_change != 0).
204 * + The message transfers use clock and SPI mode parameters
205 * previously established by setup() for this device
207 int (*transfer)(struct spi_device *spi,
208 struct spi_message *mesg);
210 /* called on release() to free memory provided by spi_master */
211 void (*cleanup)(const struct spi_device *spi);
214 static inline void *spi_master_get_devdata(struct spi_master *master)
216 return class_get_devdata(&master->cdev);
219 static inline void spi_master_set_devdata(struct spi_master *master, void *data)
221 class_set_devdata(&master->cdev, data);
224 static inline struct spi_master *spi_master_get(struct spi_master *master)
226 if (!master || !class_device_get(&master->cdev))
231 static inline void spi_master_put(struct spi_master *master)
234 class_device_put(&master->cdev);
238 /* the spi driver core manages memory for the spi_master classdev */
239 extern struct spi_master *
240 spi_alloc_master(struct device *host, unsigned size);
242 extern int spi_register_master(struct spi_master *master);
243 extern void spi_unregister_master(struct spi_master *master);
245 extern struct spi_master *spi_busnum_to_master(u16 busnum);
247 /*---------------------------------------------------------------------------*/
250 * I/O INTERFACE between SPI controller and protocol drivers
252 * Protocol drivers use a queue of spi_messages, each transferring data
253 * between the controller and memory buffers.
255 * The spi_messages themselves consist of a series of read+write transfer
256 * segments. Those segments always read the same number of bits as they
257 * write; but one or the other is easily ignored by passing a null buffer
258 * pointer. (This is unlike most types of I/O API, because SPI hardware
261 * NOTE: Allocation of spi_transfer and spi_message memory is entirely
262 * up to the protocol driver, which guarantees the integrity of both (as
263 * well as the data buffers) for as long as the message is queued.
267 * struct spi_transfer - a read/write buffer pair
268 * @tx_buf: data to be written (dma-safe memory), or NULL
269 * @rx_buf: data to be read (dma-safe memory), or NULL
270 * @tx_dma: DMA address of tx_buf, if spi_message.is_dma_mapped
271 * @rx_dma: DMA address of rx_buf, if spi_message.is_dma_mapped
272 * @len: size of rx and tx buffers (in bytes)
273 * @speed_hz: Select a speed other then the device default for this
274 * transfer. If 0 the default (from spi_device) is used.
275 * @bits_per_word: select a bits_per_word other then the device default
276 * for this transfer. If 0 the default (from spi_device) is used.
277 * @cs_change: affects chipselect after this transfer completes
278 * @delay_usecs: microseconds to delay after this transfer before
279 * (optionally) changing the chipselect status, then starting
280 * the next transfer or completing this spi_message.
281 * @transfer_list: transfers are sequenced through spi_message.transfers
283 * SPI transfers always write the same number of bytes as they read.
284 * Protocol drivers should always provide rx_buf and/or tx_buf.
285 * In some cases, they may also want to provide DMA addresses for
286 * the data being transferred; that may reduce overhead, when the
287 * underlying driver uses dma.
289 * If the transmit buffer is null, undefined data will be shifted out
290 * while filling rx_buf. If the receive buffer is null, the data
291 * shifted in will be discarded. Only "len" bytes shift out (or in).
292 * It's an error to try to shift out a partial word. (For example, by
293 * shifting out three bytes with word size of sixteen or twenty bits;
294 * the former uses two bytes per word, the latter uses four bytes.)
296 * All SPI transfers start with the relevant chipselect active. Normally
297 * it stays selected until after the last transfer in a message. Drivers
298 * can affect the chipselect signal using cs_change:
300 * (i) If the transfer isn't the last one in the message, this flag is
301 * used to make the chipselect briefly go inactive in the middle of the
302 * message. Toggling chipselect in this way may be needed to terminate
303 * a chip command, letting a single spi_message perform all of group of
304 * chip transactions together.
306 * (ii) When the transfer is the last one in the message, the chip may
307 * stay selected until the next transfer. This is purely a performance
308 * hint; the controller driver may need to select a different device
309 * for the next message.
311 * The code that submits an spi_message (and its spi_transfers)
312 * to the lower layers is responsible for managing its memory.
313 * Zero-initialize every field you don't set up explicitly, to
314 * insulate against future API updates. After you submit a message
315 * and its transfers, ignore them until its completion callback.
317 struct spi_transfer {
318 /* it's ok if tx_buf == rx_buf (right?)
319 * for MicroWire, one buffer must be null
320 * buffers must work with dma_*map_single() calls, unless
321 * spi_message.is_dma_mapped reports a pre-existing mapping
330 unsigned cs_change:1;
335 struct list_head transfer_list;
339 * struct spi_message - one multi-segment SPI transaction
340 * @transfers: list of transfer segments in this transaction
341 * @spi: SPI device to which the transaction is queued
342 * @is_dma_mapped: if true, the caller provided both dma and cpu virtual
343 * addresses for each transfer buffer
344 * @complete: called to report transaction completions
345 * @context: the argument to complete() when it's called
346 * @actual_length: the total number of bytes that were transferred in all
347 * successful segments
348 * @status: zero for success, else negative errno
349 * @queue: for use by whichever driver currently owns the message
350 * @state: for use by whichever driver currently owns the message
352 * An spi_message is used to execute an atomic sequence of data transfers,
353 * each represented by a struct spi_transfer. The sequence is "atomic"
354 * in the sense that no other spi_message may use that SPI bus until that
355 * sequence completes. On some systems, many such sequences can execute as
356 * as single programmed DMA transfer. On all systems, these messages are
357 * queued, and might complete after transactions to other devices. Messages
358 * sent to a given spi_device are alway executed in FIFO order.
360 * The code that submits an spi_message (and its spi_transfers)
361 * to the lower layers is responsible for managing its memory.
362 * Zero-initialize every field you don't set up explicitly, to
363 * insulate against future API updates. After you submit a message
364 * and its transfers, ignore them until its completion callback.
367 struct list_head transfers;
369 struct spi_device *spi;
371 unsigned is_dma_mapped:1;
373 /* REVISIT: we might want a flag affecting the behavior of the
374 * last transfer ... allowing things like "read 16 bit length L"
375 * immediately followed by "read L bytes". Basically imposing
376 * a specific message scheduling algorithm.
378 * Some controller drivers (message-at-a-time queue processing)
379 * could provide that as their default scheduling algorithm. But
380 * others (with multi-message pipelines) could need a flag to
381 * tell them about such special cases.
384 /* completion is reported through a callback */
385 void (*complete)(void *context);
387 unsigned actual_length;
390 /* for optional use by whatever driver currently owns the
391 * spi_message ... between calls to spi_async and then later
392 * complete(), that's the spi_master controller driver.
394 struct list_head queue;
398 static inline void spi_message_init(struct spi_message *m)
400 memset(m, 0, sizeof *m);
401 INIT_LIST_HEAD(&m->transfers);
405 spi_message_add_tail(struct spi_transfer *t, struct spi_message *m)
407 list_add_tail(&t->transfer_list, &m->transfers);
411 spi_transfer_del(struct spi_transfer *t)
413 list_del(&t->transfer_list);
416 /* It's fine to embed message and transaction structures in other data
417 * structures so long as you don't free them while they're in use.
420 static inline struct spi_message *spi_message_alloc(unsigned ntrans, gfp_t flags)
422 struct spi_message *m;
424 m = kzalloc(sizeof(struct spi_message)
425 + ntrans * sizeof(struct spi_transfer),
429 struct spi_transfer *t = (struct spi_transfer *)(m + 1);
431 INIT_LIST_HEAD(&m->transfers);
432 for (i = 0; i < ntrans; i++, t++)
433 spi_message_add_tail(t, m);
438 static inline void spi_message_free(struct spi_message *m)
444 * spi_setup -- setup SPI mode and clock rate
445 * @spi: the device whose settings are being modified
447 * SPI protocol drivers may need to update the transfer mode if the
448 * device doesn't work with the mode 0 default. They may likewise need
449 * to update clock rates or word sizes from initial values. This function
450 * changes those settings, and must be called from a context that can sleep.
451 * The changes take effect the next time the device is selected and data
452 * is transferred to or from it.
455 spi_setup(struct spi_device *spi)
457 return spi->master->setup(spi);
462 * spi_async -- asynchronous SPI transfer
463 * @spi: device with which data will be exchanged
464 * @message: describes the data transfers, including completion callback
466 * This call may be used in_irq and other contexts which can't sleep,
467 * as well as from task contexts which can sleep.
469 * The completion callback is invoked in a context which can't sleep.
470 * Before that invocation, the value of message->status is undefined.
471 * When the callback is issued, message->status holds either zero (to
472 * indicate complete success) or a negative error code. After that
473 * callback returns, the driver which issued the transfer request may
474 * deallocate the associated memory; it's no longer in use by any SPI
475 * core or controller driver code.
477 * Note that although all messages to a spi_device are handled in
478 * FIFO order, messages may go to different devices in other orders.
479 * Some device might be higher priority, or have various "hard" access
480 * time requirements, for example.
482 * On detection of any fault during the transfer, processing of
483 * the entire message is aborted, and the device is deselected.
484 * Until returning from the associated message completion callback,
485 * no other spi_message queued to that device will be processed.
486 * (This rule applies equally to all the synchronous transfer calls,
487 * which are wrappers around this core asynchronous primitive.)
490 spi_async(struct spi_device *spi, struct spi_message *message)
493 return spi->master->transfer(spi, message);
496 /*---------------------------------------------------------------------------*/
498 /* All these synchronous SPI transfer routines are utilities layered
499 * over the core async transfer primitive. Here, "synchronous" means
500 * they will sleep uninterruptibly until the async transfer completes.
503 extern int spi_sync(struct spi_device *spi, struct spi_message *message);
506 * spi_write - SPI synchronous write
507 * @spi: device to which data will be written
509 * @len: data buffer size
511 * This writes the buffer and returns zero or a negative error code.
512 * Callable only from contexts that can sleep.
515 spi_write(struct spi_device *spi, const u8 *buf, size_t len)
517 struct spi_transfer t = {
521 struct spi_message m;
523 spi_message_init(&m);
524 spi_message_add_tail(&t, &m);
525 return spi_sync(spi, &m);
529 * spi_read - SPI synchronous read
530 * @spi: device from which data will be read
532 * @len: data buffer size
534 * This writes the buffer and returns zero or a negative error code.
535 * Callable only from contexts that can sleep.
538 spi_read(struct spi_device *spi, u8 *buf, size_t len)
540 struct spi_transfer t = {
544 struct spi_message m;
546 spi_message_init(&m);
547 spi_message_add_tail(&t, &m);
548 return spi_sync(spi, &m);
551 /* this copies txbuf and rxbuf data; for small transfers only! */
552 extern int spi_write_then_read(struct spi_device *spi,
553 const u8 *txbuf, unsigned n_tx,
554 u8 *rxbuf, unsigned n_rx);
557 * spi_w8r8 - SPI synchronous 8 bit write followed by 8 bit read
558 * @spi: device with which data will be exchanged
559 * @cmd: command to be written before data is read back
561 * This returns the (unsigned) eight bit number returned by the
562 * device, or else a negative error code. Callable only from
563 * contexts that can sleep.
565 static inline ssize_t spi_w8r8(struct spi_device *spi, u8 cmd)
570 status = spi_write_then_read(spi, &cmd, 1, &result, 1);
572 /* return negative errno or unsigned value */
573 return (status < 0) ? status : result;
577 * spi_w8r16 - SPI synchronous 8 bit write followed by 16 bit read
578 * @spi: device with which data will be exchanged
579 * @cmd: command to be written before data is read back
581 * This returns the (unsigned) sixteen bit number returned by the
582 * device, or else a negative error code. Callable only from
583 * contexts that can sleep.
585 * The number is returned in wire-order, which is at least sometimes
588 static inline ssize_t spi_w8r16(struct spi_device *spi, u8 cmd)
593 status = spi_write_then_read(spi, &cmd, 1, (u8 *) &result, 2);
595 /* return negative errno or unsigned value */
596 return (status < 0) ? status : result;
599 /*---------------------------------------------------------------------------*/
602 * INTERFACE between board init code and SPI infrastructure.
604 * No SPI driver ever sees these SPI device table segments, but
605 * it's how the SPI core (or adapters that get hotplugged) grows
606 * the driver model tree.
608 * As a rule, SPI devices can't be probed. Instead, board init code
609 * provides a table listing the devices which are present, with enough
610 * information to bind and set up the device's driver. There's basic
611 * support for nonstatic configurations too; enough to handle adding
612 * parport adapters, or microcontrollers acting as USB-to-SPI bridges.
615 /* board-specific information about each SPI device */
616 struct spi_board_info {
617 /* the device name and module name are coupled, like platform_bus;
618 * "modalias" is normally the driver name.
620 * platform_data goes to spi_device.dev.platform_data,
621 * controller_data goes to spi_device.controller_data,
624 char modalias[KOBJ_NAME_LEN];
625 const void *platform_data;
626 void *controller_data;
629 /* slower signaling on noisy or low voltage boards */
633 /* bus_num is board specific and matches the bus_num of some
634 * spi_master that will probably be registered later.
636 * chip_select reflects how this chip is wired to that master;
637 * it's less than num_chipselect.
642 /* ... may need additional spi_device chip config data here.
643 * avoid stuff protocol drivers can set; but include stuff
644 * needed to behave without being bound to a driver:
645 * - chipselect polarity
646 * - quirks like clock rate mattering when not selected
652 spi_register_board_info(struct spi_board_info const *info, unsigned n);
654 /* board init code may ignore whether SPI is configured or not */
656 spi_register_board_info(struct spi_board_info const *info, unsigned n)
661 /* If you're hotplugging an adapter with devices (parport, usb, etc)
662 * use spi_new_device() to describe each device. You can also call
663 * spi_unregister_device() to start making that device vanish, but
664 * normally that would be handled by spi_unregister_master().
666 extern struct spi_device *
667 spi_new_device(struct spi_master *, struct spi_board_info *);
670 spi_unregister_device(struct spi_device *spi)
673 device_unregister(&spi->dev);
676 #endif /* __LINUX_SPI_H */