xref: /rk3399_rockchip-uboot/include/spi.h (revision 955a06fc55f32112b7f5b7a986e3d0157df5c2d0)
1 /*
2  * Common SPI Interface: Controller-specific definitions
3  *
4  * (C) Copyright 2001
5  * Gerald Van Baren, Custom IDEAS, vanbaren@cideas.com.
6  *
7  * SPDX-License-Identifier:	GPL-2.0+
8  */
9 
10 #ifndef _SPI_H_
11 #define _SPI_H_
12 
13 #include <common.h>
14 
15 /* SPI mode flags */
16 #define SPI_CPHA	BIT(0)			/* clock phase */
17 #define SPI_CPOL	BIT(1)			/* clock polarity */
18 #define SPI_MODE_0	(0|0)			/* (original MicroWire) */
19 #define SPI_MODE_1	(0|SPI_CPHA)
20 #define SPI_MODE_2	(SPI_CPOL|0)
21 #define SPI_MODE_3	(SPI_CPOL|SPI_CPHA)
22 #define SPI_CS_HIGH	BIT(2)			/* CS active high */
23 #define SPI_LSB_FIRST	BIT(3)			/* per-word bits-on-wire */
24 #define SPI_3WIRE	BIT(4)			/* SI/SO signals shared */
25 #define SPI_LOOP	BIT(5)			/* loopback mode */
26 #define SPI_SLAVE	BIT(6)			/* slave mode */
27 #define SPI_PREAMBLE	BIT(7)			/* Skip preamble bytes */
28 #define SPI_TX_BYTE	BIT(8)			/* transmit with 1 wire byte */
29 #define SPI_TX_DUAL	BIT(9)			/* transmit with 2 wires */
30 #define SPI_TX_QUAD	BIT(10)			/* transmit with 4 wires */
31 #define SPI_RX_SLOW	BIT(11)			/* receive with 1 wire slow */
32 #define SPI_RX_DUAL	BIT(12)			/* receive with 2 wires */
33 #define SPI_RX_QUAD	BIT(13)			/* receive with 4 wires */
34 
35 /* Header byte that marks the start of the message */
36 #define SPI_PREAMBLE_END_BYTE	0xec
37 
38 #define SPI_DEFAULT_WORDLEN	8
39 
40 #ifdef CONFIG_DM_SPI
41 /* TODO(sjg@chromium.org): Remove this and use max_hz from struct spi_slave */
42 struct dm_spi_bus {
43 	uint max_hz;
44 };
45 
46 /**
47  * struct dm_spi_platdata - platform data for all SPI slaves
48  *
49  * This describes a SPI slave, a child device of the SPI bus. To obtain this
50  * struct from a spi_slave, use dev_get_parent_platdata(dev) or
51  * dev_get_parent_platdata(slave->dev).
52  *
53  * This data is immuatable. Each time the device is probed, @max_hz and @mode
54  * will be copied to struct spi_slave.
55  *
56  * @cs:		Chip select number (0..n-1)
57  * @max_hz:	Maximum bus speed that this slave can tolerate
58  * @mode:	SPI mode to use for this device (see SPI mode flags)
59  */
60 struct dm_spi_slave_platdata {
61 	unsigned int cs;
62 	uint max_hz;
63 	uint mode;
64 };
65 
66 #endif /* CONFIG_DM_SPI */
67 
68 /**
69  * struct spi_slave - Representation of a SPI slave
70  *
71  * For driver model this is the per-child data used by the SPI bus. It can
72  * be accessed using dev_get_parent_priv() on the slave device. The SPI uclass
73  * sets uip per_child_auto_alloc_size to sizeof(struct spi_slave), and the
74  * driver should not override it. Two platform data fields (max_hz and mode)
75  * are copied into this structure to provide an initial value. This allows
76  * them to be changed, since we should never change platform data in drivers.
77  *
78  * If not using driver model, drivers are expected to extend this with
79  * controller-specific data.
80  *
81  * @dev:		SPI slave device
82  * @max_hz:		Maximum speed for this slave
83  * @speed:		Current bus speed. This is 0 until the bus is first
84  *			claimed.
85  * @bus:		ID of the bus that the slave is attached to. For
86  *			driver model this is the sequence number of the SPI
87  *			bus (bus->seq) so does not need to be stored
88  * @cs:			ID of the chip select connected to the slave.
89  * @mode:		SPI mode to use for this slave (see SPI mode flags)
90  * @wordlen:		Size of SPI word in number of bits
91  * @max_read_size:	If non-zero, the maximum number of bytes which can
92  *			be read at once.
93  * @max_write_size:	If non-zero, the maximum number of bytes which can
94  *			be written at once.
95  * @memory_map:		Address of read-only SPI flash access.
96  * @flags:		Indication of SPI flags.
97  */
98 struct spi_slave {
99 #ifdef CONFIG_DM_SPI
100 	struct udevice *dev;	/* struct spi_slave is dev->parentdata */
101 	uint max_hz;
102 	uint speed;
103 #else
104 	unsigned int bus;
105 	unsigned int cs;
106 #endif
107 	uint mode;
108 	unsigned int wordlen;
109 	unsigned int max_read_size;
110 	unsigned int max_write_size;
111 	void *memory_map;
112 	u8 option;
113 
114 	u8 flags;
115 #define SPI_XFER_BEGIN		BIT(0)	/* Assert CS before transfer */
116 #define SPI_XFER_END		BIT(1)	/* Deassert CS after transfer */
117 #define SPI_XFER_ONCE		(SPI_XFER_BEGIN | SPI_XFER_END)
118 #define SPI_XFER_MMAP		BIT(2)	/* Memory Mapped start */
119 #define SPI_XFER_MMAP_END	BIT(3)	/* Memory Mapped End */
120 };
121 
122 /**
123  * Initialization, must be called once on start up.
124  *
125  * TODO: I don't think we really need this.
126  */
127 void spi_init(void);
128 
129 /**
130  * spi_do_alloc_slave - Allocate a new SPI slave (internal)
131  *
132  * Allocate and zero all fields in the spi slave, and set the bus/chip
133  * select. Use the helper macro spi_alloc_slave() to call this.
134  *
135  * @offset:	Offset of struct spi_slave within slave structure.
136  * @size:	Size of slave structure.
137  * @bus:	Bus ID of the slave chip.
138  * @cs:		Chip select ID of the slave chip on the specified bus.
139  */
140 void *spi_do_alloc_slave(int offset, int size, unsigned int bus,
141 			 unsigned int cs);
142 
143 /**
144  * spi_alloc_slave - Allocate a new SPI slave
145  *
146  * Allocate and zero all fields in the spi slave, and set the bus/chip
147  * select.
148  *
149  * @_struct:	Name of structure to allocate (e.g. struct tegra_spi).
150  *		This structure must contain a member 'struct spi_slave *slave'.
151  * @bus:	Bus ID of the slave chip.
152  * @cs:		Chip select ID of the slave chip on the specified bus.
153  */
154 #define spi_alloc_slave(_struct, bus, cs) \
155 	spi_do_alloc_slave(offsetof(_struct, slave), \
156 			    sizeof(_struct), bus, cs)
157 
158 /**
159  * spi_alloc_slave_base - Allocate a new SPI slave with no private data
160  *
161  * Allocate and zero all fields in the spi slave, and set the bus/chip
162  * select.
163  *
164  * @bus:	Bus ID of the slave chip.
165  * @cs:		Chip select ID of the slave chip on the specified bus.
166  */
167 #define spi_alloc_slave_base(bus, cs) \
168 	spi_do_alloc_slave(0, sizeof(struct spi_slave), bus, cs)
169 
170 /**
171  * Set up communications parameters for a SPI slave.
172  *
173  * This must be called once for each slave. Note that this function
174  * usually doesn't touch any actual hardware, it only initializes the
175  * contents of spi_slave so that the hardware can be easily
176  * initialized later.
177  *
178  * @bus:	Bus ID of the slave chip.
179  * @cs:		Chip select ID of the slave chip on the specified bus.
180  * @max_hz:	Maximum SCK rate in Hz.
181  * @mode:	Clock polarity, clock phase and other parameters.
182  *
183  * Returns: A spi_slave reference that can be used in subsequent SPI
184  * calls, or NULL if one or more of the parameters are not supported.
185  */
186 struct spi_slave *spi_setup_slave(unsigned int bus, unsigned int cs,
187 		unsigned int max_hz, unsigned int mode);
188 
189 /**
190  * Free any memory associated with a SPI slave.
191  *
192  * @slave:	The SPI slave
193  */
194 void spi_free_slave(struct spi_slave *slave);
195 
196 /**
197  * Claim the bus and prepare it for communication with a given slave.
198  *
199  * This must be called before doing any transfers with a SPI slave. It
200  * will enable and initialize any SPI hardware as necessary, and make
201  * sure that the SCK line is in the correct idle state. It is not
202  * allowed to claim the same bus for several slaves without releasing
203  * the bus in between.
204  *
205  * @slave:	The SPI slave
206  *
207  * Returns: 0 if the bus was claimed successfully, or a negative value
208  * if it wasn't.
209  */
210 int spi_claim_bus(struct spi_slave *slave);
211 
212 /**
213  * Release the SPI bus
214  *
215  * This must be called once for every call to spi_claim_bus() after
216  * all transfers have finished. It may disable any SPI hardware as
217  * appropriate.
218  *
219  * @slave:	The SPI slave
220  */
221 void spi_release_bus(struct spi_slave *slave);
222 
223 /**
224  * Set the word length for SPI transactions
225  *
226  * Set the word length (number of bits per word) for SPI transactions.
227  *
228  * @slave:	The SPI slave
229  * @wordlen:	The number of bits in a word
230  *
231  * Returns: 0 on success, -1 on failure.
232  */
233 int spi_set_wordlen(struct spi_slave *slave, unsigned int wordlen);
234 
235 /**
236  * SPI transfer
237  *
238  * This writes "bitlen" bits out the SPI MOSI port and simultaneously clocks
239  * "bitlen" bits in the SPI MISO port.  That's just the way SPI works.
240  *
241  * The source of the outgoing bits is the "dout" parameter and the
242  * destination of the input bits is the "din" parameter.  Note that "dout"
243  * and "din" can point to the same memory location, in which case the
244  * input data overwrites the output data (since both are buffered by
245  * temporary variables, this is OK).
246  *
247  * spi_xfer() interface:
248  * @slave:	The SPI slave which will be sending/receiving the data.
249  * @bitlen:	How many bits to write and read.
250  * @dout:	Pointer to a string of bits to send out.  The bits are
251  *		held in a byte array and are sent MSB first.
252  * @din:	Pointer to a string of bits that will be filled in.
253  * @flags:	A bitwise combination of SPI_XFER_* flags.
254  *
255  * Returns: 0 on success, not 0 on failure
256  */
257 int  spi_xfer(struct spi_slave *slave, unsigned int bitlen, const void *dout,
258 		void *din, unsigned long flags);
259 
260 /* Copy memory mapped data */
261 void spi_flash_copy_mmap(void *data, void *offset, size_t len);
262 
263 /**
264  * Determine if a SPI chipselect is valid.
265  * This function is provided by the board if the low-level SPI driver
266  * needs it to determine if a given chipselect is actually valid.
267  *
268  * Returns: 1 if bus:cs identifies a valid chip on this board, 0
269  * otherwise.
270  */
271 int spi_cs_is_valid(unsigned int bus, unsigned int cs);
272 
273 #ifndef CONFIG_DM_SPI
274 /**
275  * Activate a SPI chipselect.
276  * This function is provided by the board code when using a driver
277  * that can't control its chipselects automatically (e.g.
278  * common/soft_spi.c). When called, it should activate the chip select
279  * to the device identified by "slave".
280  */
281 void spi_cs_activate(struct spi_slave *slave);
282 
283 /**
284  * Deactivate a SPI chipselect.
285  * This function is provided by the board code when using a driver
286  * that can't control its chipselects automatically (e.g.
287  * common/soft_spi.c). When called, it should deactivate the chip
288  * select to the device identified by "slave".
289  */
290 void spi_cs_deactivate(struct spi_slave *slave);
291 
292 /**
293  * Set transfer speed.
294  * This sets a new speed to be applied for next spi_xfer().
295  * @slave:	The SPI slave
296  * @hz:		The transfer speed
297  */
298 void spi_set_speed(struct spi_slave *slave, uint hz);
299 #endif
300 
301 /**
302  * Write 8 bits, then read 8 bits.
303  * @slave:	The SPI slave we're communicating with
304  * @byte:	Byte to be written
305  *
306  * Returns: The value that was read, or a negative value on error.
307  *
308  * TODO: This function probably shouldn't be inlined.
309  */
310 static inline int spi_w8r8(struct spi_slave *slave, unsigned char byte)
311 {
312 	unsigned char dout[2];
313 	unsigned char din[2];
314 	int ret;
315 
316 	dout[0] = byte;
317 	dout[1] = 0;
318 
319 	ret = spi_xfer(slave, 16, dout, din, SPI_XFER_BEGIN | SPI_XFER_END);
320 	return ret < 0 ? ret : din[1];
321 }
322 
323 /**
324  * Set up a SPI slave for a particular device tree node
325  *
326  * This calls spi_setup_slave() with the correct bus number. Call
327  * spi_free_slave() to free it later.
328  *
329  * @param blob:		Device tree blob
330  * @param slave_node:	Slave node to use
331  * @param spi_node:	SPI peripheral node to use
332  * @return pointer to new spi_slave structure
333  */
334 struct spi_slave *spi_setup_slave_fdt(const void *blob, int slave_node,
335 				      int spi_node);
336 
337 /**
338  * spi_base_setup_slave_fdt() - helper function to set up a SPI slace
339  *
340  * This decodes SPI properties from the slave node to determine the
341  * chip select and SPI parameters.
342  *
343  * @blob:	Device tree blob
344  * @busnum:	Bus number to use
345  * @node:	Device tree node for the SPI bus
346  */
347 struct spi_slave *spi_base_setup_slave_fdt(const void *blob, int busnum,
348 					   int node);
349 
350 #ifdef CONFIG_DM_SPI
351 
352 /**
353  * struct spi_cs_info - Information about a bus chip select
354  *
355  * @dev:	Connected device, or NULL if none
356  */
357 struct spi_cs_info {
358 	struct udevice *dev;
359 };
360 
361 /**
362  * struct struct dm_spi_ops - Driver model SPI operations
363  *
364  * The uclass interface is implemented by all SPI devices which use
365  * driver model.
366  */
367 struct dm_spi_ops {
368 	/**
369 	 * Claim the bus and prepare it for communication.
370 	 *
371 	 * The device provided is the slave device. It's parent controller
372 	 * will be used to provide the communication.
373 	 *
374 	 * This must be called before doing any transfers with a SPI slave. It
375 	 * will enable and initialize any SPI hardware as necessary, and make
376 	 * sure that the SCK line is in the correct idle state. It is not
377 	 * allowed to claim the same bus for several slaves without releasing
378 	 * the bus in between.
379 	 *
380 	 * @dev:	The SPI slave
381 	 *
382 	 * Returns: 0 if the bus was claimed successfully, or a negative value
383 	 * if it wasn't.
384 	 */
385 	int (*claim_bus)(struct udevice *dev);
386 
387 	/**
388 	 * Release the SPI bus
389 	 *
390 	 * This must be called once for every call to spi_claim_bus() after
391 	 * all transfers have finished. It may disable any SPI hardware as
392 	 * appropriate.
393 	 *
394 	 * @dev:	The SPI slave
395 	 */
396 	int (*release_bus)(struct udevice *dev);
397 
398 	/**
399 	 * Set the word length for SPI transactions
400 	 *
401 	 * Set the word length (number of bits per word) for SPI transactions.
402 	 *
403 	 * @bus:	The SPI slave
404 	 * @wordlen:	The number of bits in a word
405 	 *
406 	 * Returns: 0 on success, -ve on failure.
407 	 */
408 	int (*set_wordlen)(struct udevice *dev, unsigned int wordlen);
409 
410 	/**
411 	 * SPI transfer
412 	 *
413 	 * This writes "bitlen" bits out the SPI MOSI port and simultaneously
414 	 * clocks "bitlen" bits in the SPI MISO port.  That's just the way SPI
415 	 * works.
416 	 *
417 	 * The source of the outgoing bits is the "dout" parameter and the
418 	 * destination of the input bits is the "din" parameter.  Note that
419 	 * "dout" and "din" can point to the same memory location, in which
420 	 * case the input data overwrites the output data (since both are
421 	 * buffered by temporary variables, this is OK).
422 	 *
423 	 * spi_xfer() interface:
424 	 * @dev:	The slave device to communicate with
425 	 * @bitlen:	How many bits to write and read.
426 	 * @dout:	Pointer to a string of bits to send out.  The bits are
427 	 *		held in a byte array and are sent MSB first.
428 	 * @din:	Pointer to a string of bits that will be filled in.
429 	 * @flags:	A bitwise combination of SPI_XFER_* flags.
430 	 *
431 	 * Returns: 0 on success, not -1 on failure
432 	 */
433 	int (*xfer)(struct udevice *dev, unsigned int bitlen, const void *dout,
434 		    void *din, unsigned long flags);
435 
436 	/**
437 	 * Optimized handlers for SPI memory-like operations.
438 	 *
439 	 * Optimized/dedicated operations for interactions with SPI memory. This
440 	 * field is optional and should only be implemented if the controller
441 	 * has native support for memory like operations.
442 	 */
443 	const struct spi_controller_mem_ops *mem_ops;
444 
445 	/**
446 	 * Set transfer speed.
447 	 * This sets a new speed to be applied for next spi_xfer().
448 	 * @bus:	The SPI bus
449 	 * @hz:		The transfer speed
450 	 * @return 0 if OK, -ve on error
451 	 */
452 	int (*set_speed)(struct udevice *bus, uint hz);
453 
454 	/**
455 	 * Set the SPI mode/flags
456 	 *
457 	 * It is unclear if we want to set speed and mode together instead
458 	 * of separately.
459 	 *
460 	 * @bus:	The SPI bus
461 	 * @mode:	Requested SPI mode (SPI_... flags)
462 	 * @return 0 if OK, -ve on error
463 	 */
464 	int (*set_mode)(struct udevice *bus, uint mode);
465 
466 	/**
467 	 * Get information on a chip select
468 	 *
469 	 * This is only called when the SPI uclass does not know about a
470 	 * chip select, i.e. it has no attached device. It gives the driver
471 	 * a chance to allow activity on that chip select even so.
472 	 *
473 	 * @bus:	The SPI bus
474 	 * @cs:		The chip select (0..n-1)
475 	 * @info:	Returns information about the chip select, if valid.
476 	 *		On entry info->dev is NULL
477 	 * @return 0 if OK (and @info is set up), -ENODEV if the chip select
478 	 *	   is invalid, other -ve value on error
479 	 */
480 	int (*cs_info)(struct udevice *bus, uint cs, struct spi_cs_info *info);
481 };
482 
483 struct dm_spi_emul_ops {
484 	/**
485 	 * SPI transfer
486 	 *
487 	 * This writes "bitlen" bits out the SPI MOSI port and simultaneously
488 	 * clocks "bitlen" bits in the SPI MISO port.  That's just the way SPI
489 	 * works. Here the device is a slave.
490 	 *
491 	 * The source of the outgoing bits is the "dout" parameter and the
492 	 * destination of the input bits is the "din" parameter.  Note that
493 	 * "dout" and "din" can point to the same memory location, in which
494 	 * case the input data overwrites the output data (since both are
495 	 * buffered by temporary variables, this is OK).
496 	 *
497 	 * spi_xfer() interface:
498 	 * @slave:	The SPI slave which will be sending/receiving the data.
499 	 * @bitlen:	How many bits to write and read.
500 	 * @dout:	Pointer to a string of bits sent to the device. The
501 	 *		bits are held in a byte array and are sent MSB first.
502 	 * @din:	Pointer to a string of bits that will be sent back to
503 	 *		the master.
504 	 * @flags:	A bitwise combination of SPI_XFER_* flags.
505 	 *
506 	 * Returns: 0 on success, not -1 on failure
507 	 */
508 	int (*xfer)(struct udevice *slave, unsigned int bitlen,
509 		    const void *dout, void *din, unsigned long flags);
510 };
511 
512 /**
513  * spi_find_bus_and_cs() - Find bus and slave devices by number
514  *
515  * Given a bus number and chip select, this finds the corresponding bus
516  * device and slave device. Neither device is activated by this function,
517  * although they may have been activated previously.
518  *
519  * @busnum:	SPI bus number
520  * @cs:		Chip select to look for
521  * @busp:	Returns bus device
522  * @devp:	Return slave device
523  * @return 0 if found, -ENODEV on error
524  */
525 int spi_find_bus_and_cs(int busnum, int cs, struct udevice **busp,
526 			struct udevice **devp);
527 
528 /**
529  * spi_get_bus_and_cs() - Find and activate bus and slave devices by number
530  *
531  * Given a bus number and chip select, this finds the corresponding bus
532  * device and slave device.
533  *
534  * If no such slave exists, and drv_name is not NULL, then a new slave device
535  * is automatically bound on this chip select.
536  *
537  * Ths new slave device is probed ready for use with the given speed and mode.
538  *
539  * @busnum:	SPI bus number
540  * @cs:		Chip select to look for
541  * @speed:	SPI speed to use for this slave
542  * @mode:	SPI mode to use for this slave
543  * @drv_name:	Name of driver to attach to this chip select
544  * @dev_name:	Name of the new device thus created
545  * @busp:	Returns bus device
546  * @devp:	Return slave device
547  * @return 0 if found, -ve on error
548  */
549 int spi_get_bus_and_cs(int busnum, int cs, int speed, int mode,
550 			const char *drv_name, const char *dev_name,
551 			struct udevice **busp, struct spi_slave **devp);
552 
553 /**
554  * spi_chip_select() - Get the chip select for a slave
555  *
556  * @return the chip select this slave is attached to
557  */
558 int spi_chip_select(struct udevice *slave);
559 
560 /**
561  * spi_find_chip_select() - Find the slave attached to chip select
562  *
563  * @bus:	SPI bus to search
564  * @cs:		Chip select to look for
565  * @devp:	Returns the slave device if found
566  * @return 0 if found, -ENODEV on error
567  */
568 int spi_find_chip_select(struct udevice *bus, int cs, struct udevice **devp);
569 
570 /**
571  * spi_slave_ofdata_to_platdata() - decode standard SPI platform data
572  *
573  * This decodes the speed and mode for a slave from a device tree node
574  *
575  * @blob:	Device tree blob
576  * @node:	Node offset to read from
577  * @plat:	Place to put the decoded information
578  */
579 int spi_slave_ofdata_to_platdata(struct udevice *dev,
580 				 struct dm_spi_slave_platdata *plat);
581 
582 /**
583  * spi_cs_info() - Check information on a chip select
584  *
585  * This checks a particular chip select on a bus to see if it has a device
586  * attached, or is even valid.
587  *
588  * @bus:	The SPI bus
589  * @cs:		The chip select (0..n-1)
590  * @info:	Returns information about the chip select, if valid
591  * @return 0 if OK (and @info is set up), -ENODEV if the chip select
592  *	   is invalid, other -ve value on error
593  */
594 int spi_cs_info(struct udevice *bus, uint cs, struct spi_cs_info *info);
595 
596 struct sandbox_state;
597 
598 /**
599  * sandbox_spi_get_emul() - get an emulator for a SPI slave
600  *
601  * This provides a way to attach an emulated SPI device to a particular SPI
602  * slave, so that xfer() operations on the slave will be handled by the
603  * emulator. If a emulator already exists on that chip select it is returned.
604  * Otherwise one is created.
605  *
606  * @state:	Sandbox state
607  * @bus:	SPI bus requesting the emulator
608  * @slave:	SPI slave device requesting the emulator
609  * @emuip:	Returns pointer to emulator
610  * @return 0 if OK, -ve on error
611  */
612 int sandbox_spi_get_emul(struct sandbox_state *state,
613 			 struct udevice *bus, struct udevice *slave,
614 			 struct udevice **emulp);
615 
616 /**
617  * Claim the bus and prepare it for communication with a given slave.
618  *
619  * This must be called before doing any transfers with a SPI slave. It
620  * will enable and initialize any SPI hardware as necessary, and make
621  * sure that the SCK line is in the correct idle state. It is not
622  * allowed to claim the same bus for several slaves without releasing
623  * the bus in between.
624  *
625  * @dev:	The SPI slave device
626  *
627  * Returns: 0 if the bus was claimed successfully, or a negative value
628  * if it wasn't.
629  */
630 int dm_spi_claim_bus(struct udevice *dev);
631 
632 /**
633  * Release the SPI bus
634  *
635  * This must be called once for every call to dm_spi_claim_bus() after
636  * all transfers have finished. It may disable any SPI hardware as
637  * appropriate.
638  *
639  * @slave:	The SPI slave device
640  */
641 void dm_spi_release_bus(struct udevice *dev);
642 
643 /**
644  * SPI transfer
645  *
646  * This writes "bitlen" bits out the SPI MOSI port and simultaneously clocks
647  * "bitlen" bits in the SPI MISO port.  That's just the way SPI works.
648  *
649  * The source of the outgoing bits is the "dout" parameter and the
650  * destination of the input bits is the "din" parameter.  Note that "dout"
651  * and "din" can point to the same memory location, in which case the
652  * input data overwrites the output data (since both are buffered by
653  * temporary variables, this is OK).
654  *
655  * dm_spi_xfer() interface:
656  * @dev:	The SPI slave device which will be sending/receiving the data.
657  * @bitlen:	How many bits to write and read.
658  * @dout:	Pointer to a string of bits to send out.  The bits are
659  *		held in a byte array and are sent MSB first.
660  * @din:	Pointer to a string of bits that will be filled in.
661  * @flags:	A bitwise combination of SPI_XFER_* flags.
662  *
663  * Returns: 0 on success, not 0 on failure
664  */
665 int dm_spi_xfer(struct udevice *dev, unsigned int bitlen,
666 		const void *dout, void *din, unsigned long flags);
667 
668 /* Access the operations for a SPI device */
669 #define spi_get_ops(dev)	((struct dm_spi_ops *)(dev)->driver->ops)
670 #define spi_emul_get_ops(dev)	((struct dm_spi_emul_ops *)(dev)->driver->ops)
671 #endif /* CONFIG_DM_SPI */
672 
673 #endif	/* _SPI_H_ */
674