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.
22 #include <linux/device.h>
25 * INTERFACES between SPI master-side drivers and SPI infrastructure.
26 * (There's no SPI slave support for Linux yet...)
28 extern struct bus_type spi_bus_type;
31 * struct spi_device - Master side proxy for an SPI slave device
32 * @dev: Driver model representation of the device.
33 * @master: SPI controller used with the device.
34 * @max_speed_hz: Maximum clock rate to be used with this chip
35 * (on this board); may be changed by the device's driver.
36 * The spi_transfer.speed_hz can override this for each transfer.
37 * @chip_select: Chipselect, distinguishing chips handled by @master.
38 * @mode: The spi mode defines how data is clocked out and in.
39 * This may be changed by the device's driver.
40 * The "active low" default for chipselect mode can be overridden
41 * (by specifying SPI_CS_HIGH) as can the "MSB first" default for
42 * each word in a transfer (by specifying SPI_LSB_FIRST).
43 * @bits_per_word: Data transfers involve one or more words; word sizes
44 * like eight or 12 bits are common. In-memory wordsizes are
45 * powers of two bytes (e.g. 20 bit samples use 32 bits).
46 * This may be changed by the device's driver, or left at the
47 * default (0) indicating protocol words are eight bit bytes.
48 * The spi_transfer.bits_per_word can override this for each transfer.
49 * @irq: Negative, or the number passed to request_irq() to receive
50 * interrupts from this device.
51 * @controller_state: Controller's runtime state
52 * @controller_data: Board-specific definitions for controller, such as
53 * FIFO initialization parameters; from board_info.controller_data
54 * @modalias: Name of the driver to use with this device, or an alias
55 * for that name. This appears in the sysfs "modalias" attribute
56 * for driver coldplugging, and in uevents used for hotplugging
58 * A @spi_device is used to interchange data between an SPI slave
59 * (usually a discrete chip) and CPU memory.
61 * In @dev, the platform_data is used to hold information about this
62 * device that's meaningful to the device's protocol driver, but not
63 * to its controller. One example might be an identifier for a chip
64 * variant with slightly different functionality; another might be
65 * information about how this particular board wires the chip's pins.
69 struct spi_master *master;
73 #define SPI_CPHA 0x01 /* clock phase */
74 #define SPI_CPOL 0x02 /* clock polarity */
75 #define SPI_MODE_0 (0|0) /* (original MicroWire) */
76 #define SPI_MODE_1 (0|SPI_CPHA)
77 #define SPI_MODE_2 (SPI_CPOL|0)
78 #define SPI_MODE_3 (SPI_CPOL|SPI_CPHA)
79 #define SPI_CS_HIGH 0x04 /* chipselect active high? */
80 #define SPI_LSB_FIRST 0x08 /* per-word bits-on-wire */
81 #define SPI_3WIRE 0x10 /* SI/SO signals shared */
82 #define SPI_LOOP 0x20 /* loopback mode */
85 void *controller_state;
86 void *controller_data;
90 * likely need more hooks for more protocol options affecting how
91 * the controller talks to each chip, like:
92 * - memory packing (12 bit samples into low bits, others zeroed)
94 * - drop chipselect after each word
100 static inline struct spi_device *to_spi_device(struct device *dev)
102 return dev ? container_of(dev, struct spi_device, dev) : NULL;
105 /* most drivers won't need to care about device refcounting */
106 static inline struct spi_device *spi_dev_get(struct spi_device *spi)
108 return (spi && get_device(&spi->dev)) ? spi : NULL;
111 static inline void spi_dev_put(struct spi_device *spi)
114 put_device(&spi->dev);
117 /* ctldata is for the bus_master driver's runtime state */
118 static inline void *spi_get_ctldata(struct spi_device *spi)
120 return spi->controller_state;
123 static inline void spi_set_ctldata(struct spi_device *spi, void *state)
125 spi->controller_state = state;
128 /* device driver data */
130 static inline void spi_set_drvdata(struct spi_device *spi, void *data)
132 dev_set_drvdata(&spi->dev, data);
135 static inline void *spi_get_drvdata(struct spi_device *spi)
137 return dev_get_drvdata(&spi->dev);
145 * struct spi_driver - Host side "protocol" driver
146 * @probe: Binds this driver to the spi device. Drivers can verify
147 * that the device is actually present, and may need to configure
148 * characteristics (such as bits_per_word) which weren't needed for
149 * the initial configuration done during system setup.
150 * @remove: Unbinds this driver from the spi device
151 * @shutdown: Standard shutdown callback used during system state
152 * transitions such as powerdown/halt and kexec
153 * @suspend: Standard suspend callback used during system state transitions
154 * @resume: Standard resume callback used during system state transitions
155 * @driver: SPI device drivers should initialize the name and owner
156 * field of this structure.
158 * This represents the kind of device driver that uses SPI messages to
159 * interact with the hardware at the other end of a SPI link. It's called
160 * a "protocol" driver because it works through messages rather than talking
161 * directly to SPI hardware (which is what the underlying SPI controller
162 * driver does to pass those messages). These protocols are defined in the
163 * specification for the device(s) supported by the driver.
165 * As a rule, those device protocols represent the lowest level interface
166 * supported by a driver, and it will support upper level interfaces too.
167 * Examples of such upper levels include frameworks like MTD, networking,
168 * MMC, RTC, filesystem character device nodes, and hardware monitoring.
171 int (*probe)(struct spi_device *spi);
172 int (*remove)(struct spi_device *spi);
173 void (*shutdown)(struct spi_device *spi);
174 int (*suspend)(struct spi_device *spi, pm_message_t mesg);
175 int (*resume)(struct spi_device *spi);
176 struct device_driver driver;
179 static inline struct spi_driver *to_spi_driver(struct device_driver *drv)
181 return drv ? container_of(drv, struct spi_driver, driver) : NULL;
184 extern int spi_register_driver(struct spi_driver *sdrv);
187 * spi_unregister_driver - reverse effect of spi_register_driver
188 * @sdrv: the driver to unregister
191 static inline void spi_unregister_driver(struct spi_driver *sdrv)
194 driver_unregister(&sdrv->driver);
199 * struct spi_master - interface to SPI master controller
200 * @dev: device interface to this driver
201 * @bus_num: board-specific (and often SOC-specific) identifier for a
202 * given SPI controller.
203 * @num_chipselect: chipselects are used to distinguish individual
204 * SPI slaves, and are numbered from zero to num_chipselects.
205 * each slave has a chipselect signal, but it's common that not
206 * every chipselect is connected to a slave.
207 * @dma_alignment: SPI controller constraint on DMA buffers alignment.
208 * @setup: updates the device mode and clocking records used by a
209 * device's SPI controller; protocol code may call this. This
210 * must fail if an unrecognized or unsupported mode is requested.
211 * It's always safe to call this unless transfers are pending on
212 * the device whose settings are being modified.
213 * @transfer: adds a message to the controller's transfer queue.
214 * @cleanup: frees controller-specific state
216 * Each SPI master controller can communicate with one or more @spi_device
217 * children. These make a small bus, sharing MOSI, MISO and SCK signals
218 * but not chip select signals. Each device may be configured to use a
219 * different clock rate, since those shared signals are ignored unless
220 * the chip is selected.
222 * The driver for an SPI controller manages access to those devices through
223 * a queue of spi_message transactions, copying data between CPU memory and
224 * an SPI slave device. For each such message it queues, it calls the
225 * message's completion function when the transaction completes.
230 /* other than negative (== assign one dynamically), bus_num is fully
231 * board-specific. usually that simplifies to being SOC-specific.
232 * example: one SOC has three SPI controllers, numbered 0..2,
233 * and one board's schematics might show it using SPI-2. software
234 * would normally use bus_num=2 for that controller.
238 /* chipselects will be integral to many controllers; some others
239 * might use board-specific GPIOs.
243 /* some SPI controllers pose alignment requirements on DMAable
244 * buffers; let protocol drivers know about these requirements.
248 /* setup mode and clock, etc (spi driver may call many times) */
249 int (*setup)(struct spi_device *spi);
251 /* bidirectional bulk transfers
253 * + The transfer() method may not sleep; its main role is
254 * just to add the message to the queue.
255 * + For now there's no remove-from-queue operation, or
256 * any other request management
257 * + To a given spi_device, message queueing is pure fifo
259 * + The master's main job is to process its message queue,
260 * selecting a chip then transferring data
261 * + If there are multiple spi_device children, the i/o queue
262 * arbitration algorithm is unspecified (round robin, fifo,
263 * priority, reservations, preemption, etc)
265 * + Chipselect stays active during the entire message
266 * (unless modified by spi_transfer.cs_change != 0).
267 * + The message transfers use clock and SPI mode parameters
268 * previously established by setup() for this device
270 int (*transfer)(struct spi_device *spi,
271 struct spi_message *mesg);
273 /* called on release() to free memory provided by spi_master */
274 void (*cleanup)(struct spi_device *spi);
277 static inline void *spi_master_get_devdata(struct spi_master *master)
279 return dev_get_drvdata(&master->dev);
282 static inline void spi_master_set_devdata(struct spi_master *master, void *data)
284 dev_set_drvdata(&master->dev, data);
287 static inline struct spi_master *spi_master_get(struct spi_master *master)
289 if (!master || !get_device(&master->dev))
294 static inline void spi_master_put(struct spi_master *master)
297 put_device(&master->dev);
301 /* the spi driver core manages memory for the spi_master classdev */
302 extern struct spi_master *
303 spi_alloc_master(struct device *host, unsigned size);
305 extern int spi_register_master(struct spi_master *master);
306 extern void spi_unregister_master(struct spi_master *master);
308 extern struct spi_master *spi_busnum_to_master(u16 busnum);
310 /*---------------------------------------------------------------------------*/
313 * I/O INTERFACE between SPI controller and protocol drivers
315 * Protocol drivers use a queue of spi_messages, each transferring data
316 * between the controller and memory buffers.
318 * The spi_messages themselves consist of a series of read+write transfer
319 * segments. Those segments always read the same number of bits as they
320 * write; but one or the other is easily ignored by passing a null buffer
321 * pointer. (This is unlike most types of I/O API, because SPI hardware
324 * NOTE: Allocation of spi_transfer and spi_message memory is entirely
325 * up to the protocol driver, which guarantees the integrity of both (as
326 * well as the data buffers) for as long as the message is queued.
330 * struct spi_transfer - a read/write buffer pair
331 * @tx_buf: data to be written (dma-safe memory), or NULL
332 * @rx_buf: data to be read (dma-safe memory), or NULL
333 * @tx_dma: DMA address of tx_buf, if @spi_message.is_dma_mapped
334 * @rx_dma: DMA address of rx_buf, if @spi_message.is_dma_mapped
335 * @len: size of rx and tx buffers (in bytes)
336 * @speed_hz: Select a speed other than the device default for this
337 * transfer. If 0 the default (from @spi_device) is used.
338 * @bits_per_word: select a bits_per_word other than the device default
339 * for this transfer. If 0 the default (from @spi_device) is used.
340 * @cs_change: affects chipselect after this transfer completes
341 * @delay_usecs: microseconds to delay after this transfer before
342 * (optionally) changing the chipselect status, then starting
343 * the next transfer or completing this @spi_message.
344 * @transfer_list: transfers are sequenced through @spi_message.transfers
346 * SPI transfers always write the same number of bytes as they read.
347 * Protocol drivers should always provide @rx_buf and/or @tx_buf.
348 * In some cases, they may also want to provide DMA addresses for
349 * the data being transferred; that may reduce overhead, when the
350 * underlying driver uses dma.
352 * If the transmit buffer is null, zeroes will be shifted out
353 * while filling @rx_buf. If the receive buffer is null, the data
354 * shifted in will be discarded. Only "len" bytes shift out (or in).
355 * It's an error to try to shift out a partial word. (For example, by
356 * shifting out three bytes with word size of sixteen or twenty bits;
357 * the former uses two bytes per word, the latter uses four bytes.)
359 * In-memory data values are always in native CPU byte order, translated
360 * from the wire byte order (big-endian except with SPI_LSB_FIRST). So
361 * for example when bits_per_word is sixteen, buffers are 2N bytes long
362 * (@len = 2N) and hold N sixteen bit words in CPU byte order.
364 * When the word size of the SPI transfer is not a power-of-two multiple
365 * of eight bits, those in-memory words include extra bits. In-memory
366 * words are always seen by protocol drivers as right-justified, so the
367 * undefined (rx) or unused (tx) bits are always the most significant bits.
369 * All SPI transfers start with the relevant chipselect active. Normally
370 * it stays selected until after the last transfer in a message. Drivers
371 * can affect the chipselect signal using cs_change.
373 * (i) If the transfer isn't the last one in the message, this flag is
374 * used to make the chipselect briefly go inactive in the middle of the
375 * message. Toggling chipselect in this way may be needed to terminate
376 * a chip command, letting a single spi_message perform all of group of
377 * chip transactions together.
379 * (ii) When the transfer is the last one in the message, the chip may
380 * stay selected until the next transfer. On multi-device SPI busses
381 * with nothing blocking messages going to other devices, this is just
382 * a performance hint; starting a message to another device deselects
383 * this one. But in other cases, this can be used to ensure correctness.
384 * Some devices need protocol transactions to be built from a series of
385 * spi_message submissions, where the content of one message is determined
386 * by the results of previous messages and where the whole transaction
387 * ends when the chipselect goes intactive.
389 * The code that submits an spi_message (and its spi_transfers)
390 * to the lower layers is responsible for managing its memory.
391 * Zero-initialize every field you don't set up explicitly, to
392 * insulate against future API updates. After you submit a message
393 * and its transfers, ignore them until its completion callback.
395 struct spi_transfer {
396 /* it's ok if tx_buf == rx_buf (right?)
397 * for MicroWire, one buffer must be null
398 * buffers must work with dma_*map_single() calls, unless
399 * spi_message.is_dma_mapped reports a pre-existing mapping
408 unsigned cs_change:1;
413 struct list_head transfer_list;
417 * struct spi_message - one multi-segment SPI transaction
418 * @transfers: list of transfer segments in this transaction
419 * @spi: SPI device to which the transaction is queued
420 * @is_dma_mapped: if true, the caller provided both dma and cpu virtual
421 * addresses for each transfer buffer
422 * @complete: called to report transaction completions
423 * @context: the argument to complete() when it's called
424 * @actual_length: the total number of bytes that were transferred in all
425 * successful segments
426 * @status: zero for success, else negative errno
427 * @queue: for use by whichever driver currently owns the message
428 * @state: for use by whichever driver currently owns the message
430 * A @spi_message is used to execute an atomic sequence of data transfers,
431 * each represented by a struct spi_transfer. The sequence is "atomic"
432 * in the sense that no other spi_message may use that SPI bus until that
433 * sequence completes. On some systems, many such sequences can execute as
434 * as single programmed DMA transfer. On all systems, these messages are
435 * queued, and might complete after transactions to other devices. Messages
436 * sent to a given spi_device are alway executed in FIFO order.
438 * The code that submits an spi_message (and its spi_transfers)
439 * to the lower layers is responsible for managing its memory.
440 * Zero-initialize every field you don't set up explicitly, to
441 * insulate against future API updates. After you submit a message
442 * and its transfers, ignore them until its completion callback.
445 struct list_head transfers;
447 struct spi_device *spi;
449 unsigned is_dma_mapped:1;
451 /* REVISIT: we might want a flag affecting the behavior of the
452 * last transfer ... allowing things like "read 16 bit length L"
453 * immediately followed by "read L bytes". Basically imposing
454 * a specific message scheduling algorithm.
456 * Some controller drivers (message-at-a-time queue processing)
457 * could provide that as their default scheduling algorithm. But
458 * others (with multi-message pipelines) could need a flag to
459 * tell them about such special cases.
462 /* completion is reported through a callback */
463 void (*complete)(void *context);
465 unsigned actual_length;
468 /* for optional use by whatever driver currently owns the
469 * spi_message ... between calls to spi_async and then later
470 * complete(), that's the spi_master controller driver.
472 struct list_head queue;
476 static inline void spi_message_init(struct spi_message *m)
478 memset(m, 0, sizeof *m);
479 INIT_LIST_HEAD(&m->transfers);
483 spi_message_add_tail(struct spi_transfer *t, struct spi_message *m)
485 list_add_tail(&t->transfer_list, &m->transfers);
489 spi_transfer_del(struct spi_transfer *t)
491 list_del(&t->transfer_list);
494 /* It's fine to embed message and transaction structures in other data
495 * structures so long as you don't free them while they're in use.
498 static inline struct spi_message *spi_message_alloc(unsigned ntrans, gfp_t flags)
500 struct spi_message *m;
502 m = kzalloc(sizeof(struct spi_message)
503 + ntrans * sizeof(struct spi_transfer),
507 struct spi_transfer *t = (struct spi_transfer *)(m + 1);
509 INIT_LIST_HEAD(&m->transfers);
510 for (i = 0; i < ntrans; i++, t++)
511 spi_message_add_tail(t, m);
516 static inline void spi_message_free(struct spi_message *m)
522 * spi_setup - setup SPI mode and clock rate
523 * @spi: the device whose settings are being modified
524 * Context: can sleep, and no requests are queued to the device
526 * SPI protocol drivers may need to update the transfer mode if the
527 * device doesn't work with its default. They may likewise need
528 * to update clock rates or word sizes from initial values. This function
529 * changes those settings, and must be called from a context that can sleep.
530 * Except for SPI_CS_HIGH, which takes effect immediately, the changes take
531 * effect the next time the device is selected and data is transferred to
532 * or from it. When this function returns, the spi device is deselected.
534 * Note that this call will fail if the protocol driver specifies an option
535 * that the underlying controller or its driver does not support. For
536 * example, not all hardware supports wire transfers using nine bit words,
537 * LSB-first wire encoding, or active-high chipselects.
540 spi_setup(struct spi_device *spi)
542 return spi->master->setup(spi);
547 * spi_async - asynchronous SPI transfer
548 * @spi: device with which data will be exchanged
549 * @message: describes the data transfers, including completion callback
550 * Context: any (irqs may be blocked, etc)
552 * This call may be used in_irq and other contexts which can't sleep,
553 * as well as from task contexts which can sleep.
555 * The completion callback is invoked in a context which can't sleep.
556 * Before that invocation, the value of message->status is undefined.
557 * When the callback is issued, message->status holds either zero (to
558 * indicate complete success) or a negative error code. After that
559 * callback returns, the driver which issued the transfer request may
560 * deallocate the associated memory; it's no longer in use by any SPI
561 * core or controller driver code.
563 * Note that although all messages to a spi_device are handled in
564 * FIFO order, messages may go to different devices in other orders.
565 * Some device might be higher priority, or have various "hard" access
566 * time requirements, for example.
568 * On detection of any fault during the transfer, processing of
569 * the entire message is aborted, and the device is deselected.
570 * Until returning from the associated message completion callback,
571 * no other spi_message queued to that device will be processed.
572 * (This rule applies equally to all the synchronous transfer calls,
573 * which are wrappers around this core asynchronous primitive.)
576 spi_async(struct spi_device *spi, struct spi_message *message)
579 return spi->master->transfer(spi, message);
582 /*---------------------------------------------------------------------------*/
584 /* All these synchronous SPI transfer routines are utilities layered
585 * over the core async transfer primitive. Here, "synchronous" means
586 * they will sleep uninterruptibly until the async transfer completes.
589 extern int spi_sync(struct spi_device *spi, struct spi_message *message);
592 * spi_write - SPI synchronous write
593 * @spi: device to which data will be written
595 * @len: data buffer size
598 * This writes the buffer and returns zero or a negative error code.
599 * Callable only from contexts that can sleep.
602 spi_write(struct spi_device *spi, const u8 *buf, size_t len)
604 struct spi_transfer t = {
608 struct spi_message m;
610 spi_message_init(&m);
611 spi_message_add_tail(&t, &m);
612 return spi_sync(spi, &m);
616 * spi_read - SPI synchronous read
617 * @spi: device from which data will be read
619 * @len: data buffer size
622 * This reads the buffer and returns zero or a negative error code.
623 * Callable only from contexts that can sleep.
626 spi_read(struct spi_device *spi, u8 *buf, size_t len)
628 struct spi_transfer t = {
632 struct spi_message m;
634 spi_message_init(&m);
635 spi_message_add_tail(&t, &m);
636 return spi_sync(spi, &m);
639 /* this copies txbuf and rxbuf data; for small transfers only! */
640 extern int spi_write_then_read(struct spi_device *spi,
641 const u8 *txbuf, unsigned n_tx,
642 u8 *rxbuf, unsigned n_rx);
645 * spi_w8r8 - SPI synchronous 8 bit write followed by 8 bit read
646 * @spi: device with which data will be exchanged
647 * @cmd: command to be written before data is read back
650 * This returns the (unsigned) eight bit number returned by the
651 * device, or else a negative error code. Callable only from
652 * contexts that can sleep.
654 static inline ssize_t spi_w8r8(struct spi_device *spi, u8 cmd)
659 status = spi_write_then_read(spi, &cmd, 1, &result, 1);
661 /* return negative errno or unsigned value */
662 return (status < 0) ? status : result;
666 * spi_w8r16 - SPI synchronous 8 bit write followed by 16 bit read
667 * @spi: device with which data will be exchanged
668 * @cmd: command to be written before data is read back
671 * This returns the (unsigned) sixteen bit number returned by the
672 * device, or else a negative error code. Callable only from
673 * contexts that can sleep.
675 * The number is returned in wire-order, which is at least sometimes
678 static inline ssize_t spi_w8r16(struct spi_device *spi, u8 cmd)
683 status = spi_write_then_read(spi, &cmd, 1, (u8 *) &result, 2);
685 /* return negative errno or unsigned value */
686 return (status < 0) ? status : result;
689 /*---------------------------------------------------------------------------*/
692 * INTERFACE between board init code and SPI infrastructure.
694 * No SPI driver ever sees these SPI device table segments, but
695 * it's how the SPI core (or adapters that get hotplugged) grows
696 * the driver model tree.
698 * As a rule, SPI devices can't be probed. Instead, board init code
699 * provides a table listing the devices which are present, with enough
700 * information to bind and set up the device's driver. There's basic
701 * support for nonstatic configurations too; enough to handle adding
702 * parport adapters, or microcontrollers acting as USB-to-SPI bridges.
706 * struct spi_board_info - board-specific template for a SPI device
707 * @modalias: Initializes spi_device.modalias; identifies the driver.
708 * @platform_data: Initializes spi_device.platform_data; the particular
709 * data stored there is driver-specific.
710 * @controller_data: Initializes spi_device.controller_data; some
711 * controllers need hints about hardware setup, e.g. for DMA.
712 * @irq: Initializes spi_device.irq; depends on how the board is wired.
713 * @max_speed_hz: Initializes spi_device.max_speed_hz; based on limits
714 * from the chip datasheet and board-specific signal quality issues.
715 * @bus_num: Identifies which spi_master parents the spi_device; unused
716 * by spi_new_device(), and otherwise depends on board wiring.
717 * @chip_select: Initializes spi_device.chip_select; depends on how
718 * the board is wired.
719 * @mode: Initializes spi_device.mode; based on the chip datasheet, board
720 * wiring (some devices support both 3WIRE and standard modes), and
721 * possibly presence of an inverter in the chipselect path.
723 * When adding new SPI devices to the device tree, these structures serve
724 * as a partial device template. They hold information which can't always
725 * be determined by drivers. Information that probe() can establish (such
726 * as the default transfer wordsize) is not included here.
728 * These structures are used in two places. Their primary role is to
729 * be stored in tables of board-specific device descriptors, which are
730 * declared early in board initialization and then used (much later) to
731 * populate a controller's device tree after the that controller's driver
732 * initializes. A secondary (and atypical) role is as a parameter to
733 * spi_new_device() call, which happens after those controller drivers
734 * are active in some dynamic board configuration models.
736 struct spi_board_info {
737 /* the device name and module name are coupled, like platform_bus;
738 * "modalias" is normally the driver name.
740 * platform_data goes to spi_device.dev.platform_data,
741 * controller_data goes to spi_device.controller_data,
745 const void *platform_data;
746 void *controller_data;
749 /* slower signaling on noisy or low voltage boards */
753 /* bus_num is board specific and matches the bus_num of some
754 * spi_master that will probably be registered later.
756 * chip_select reflects how this chip is wired to that master;
757 * it's less than num_chipselect.
762 /* mode becomes spi_device.mode, and is essential for chips
763 * where the default of SPI_CS_HIGH = 0 is wrong.
767 /* ... may need additional spi_device chip config data here.
768 * avoid stuff protocol drivers can set; but include stuff
769 * needed to behave without being bound to a driver:
770 * - quirks like clock rate mattering when not selected
776 spi_register_board_info(struct spi_board_info const *info, unsigned n);
778 /* board init code may ignore whether SPI is configured or not */
780 spi_register_board_info(struct spi_board_info const *info, unsigned n)
785 /* If you're hotplugging an adapter with devices (parport, usb, etc)
786 * use spi_new_device() to describe each device. You can also call
787 * spi_unregister_device() to start making that device vanish, but
788 * normally that would be handled by spi_unregister_master().
790 * You can also use spi_alloc_device() and spi_add_device() to use a two
791 * stage registration sequence for each spi_device. This gives the caller
792 * some more control over the spi_device structure before it is registered,
793 * but requires that caller to initialize fields that would otherwise
794 * be defined using the board info.
796 extern struct spi_device *
797 spi_alloc_device(struct spi_master *master);
800 spi_add_device(struct spi_device *spi);
802 extern struct spi_device *
803 spi_new_device(struct spi_master *, struct spi_board_info *);
806 spi_unregister_device(struct spi_device *spi)
809 device_unregister(&spi->dev);
812 #endif /* __LINUX_SPI_H */