xref: /rk3399_rockchip-uboot/include/spi.h (revision 08fe9c294f2d699a4e8b6b18e31169a89552f967)
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 /* SPI mode flags */
14 #define SPI_CPHA	BIT(0)			/* clock phase */
15 #define SPI_CPOL	BIT(1)			/* clock polarity */
16 #define SPI_MODE_0	(0|0)			/* (original MicroWire) */
17 #define SPI_MODE_1	(0|SPI_CPHA)
18 #define SPI_MODE_2	(SPI_CPOL|0)
19 #define SPI_MODE_3	(SPI_CPOL|SPI_CPHA)
20 #define SPI_CS_HIGH	BIT(2)			/* CS active high */
21 #define SPI_LSB_FIRST	BIT(3)			/* per-word bits-on-wire */
22 #define SPI_3WIRE	BIT(4)			/* SI/SO signals shared */
23 #define SPI_LOOP	BIT(5)			/* loopback mode */
24 #define SPI_SLAVE	BIT(6)			/* slave mode */
25 #define SPI_PREAMBLE	BIT(7)			/* Skip preamble bytes */
26 #define SPI_TX_BYTE	BIT(8)			/* transmit with 1 wire byte */
27 #define SPI_TX_DUAL	BIT(9)			/* transmit with 2 wires */
28 #define SPI_TX_QUAD	BIT(10)			/* transmit with 4 wires */
29 #define SPI_RX_SLOW	BIT(11)			/* receive with 1 wire slow */
30 #define SPI_RX_FAST	BIT(12)			/* receive with 1 wire fast */
31 #define SPI_RX_DUAL	BIT(13)			/* receive with 2 wires */
32 #define SPI_RX_QUAD	BIT(14)			/* receive with 4 wires */
33 
34 /* SPI bus connection options - see enum spi_dual_flash */
35 #define SPI_CONN_DUAL_SHARED		(1 << 0)
36 #define SPI_CONN_DUAL_SEPARATED	(1 << 1)
37 
38 /* Header byte that marks the start of the message */
39 #define SPI_PREAMBLE_END_BYTE	0xec
40 
41 #define SPI_DEFAULT_WORDLEN	8
42 
43 #ifdef CONFIG_DM_SPI
44 /* TODO(sjg@chromium.org): Remove this and use max_hz from struct spi_slave */
45 struct dm_spi_bus {
46 	uint max_hz;
47 };
48 
49 /**
50  * struct dm_spi_platdata - platform data for all SPI slaves
51  *
52  * This describes a SPI slave, a child device of the SPI bus. To obtain this
53  * struct from a spi_slave, use dev_get_parent_platdata(dev) or
54  * dev_get_parent_platdata(slave->dev).
55  *
56  * This data is immuatable. Each time the device is probed, @max_hz and @mode
57  * will be copied to struct spi_slave.
58  *
59  * @cs:		Chip select number (0..n-1)
60  * @max_hz:	Maximum bus speed that this slave can tolerate
61  * @mode:	SPI mode to use for this device (see SPI mode flags)
62  */
63 struct dm_spi_slave_platdata {
64 	unsigned int cs;
65 	uint max_hz;
66 	uint mode;
67 };
68 
69 #endif /* CONFIG_DM_SPI */
70 
71 /**
72  * struct spi_slave - Representation of a SPI slave
73  *
74  * For driver model this is the per-child data used by the SPI bus. It can
75  * be accessed using dev_get_parent_priv() on the slave device. The SPI uclass
76  * sets uip per_child_auto_alloc_size to sizeof(struct spi_slave), and the
77  * driver should not override it. Two platform data fields (max_hz and mode)
78  * are copied into this structure to provide an initial value. This allows
79  * them to be changed, since we should never change platform data in drivers.
80  *
81  * If not using driver model, drivers are expected to extend this with
82  * controller-specific data.
83  *
84  * @dev:		SPI slave device
85  * @max_hz:		Maximum speed for this slave
86  * @speed:		Current bus speed. This is 0 until the bus is first
87  *			claimed.
88  * @bus:		ID of the bus that the slave is attached to. For
89  *			driver model this is the sequence number of the SPI
90  *			bus (bus->seq) so does not need to be stored
91  * @cs:			ID of the chip select connected to the slave.
92  * @mode:		SPI mode to use for this slave (see SPI mode flags)
93  * @wordlen:		Size of SPI word in number of bits
94  * @max_write_size:	If non-zero, the maximum number of bytes which can
95  *			be written at once, excluding command bytes.
96  * @memory_map:		Address of read-only SPI flash access.
97  * @option:		Varies SPI bus options - separate, shared bus.
98  * @flags:		Indication of SPI flags.
99  */
100 struct spi_slave {
101 #ifdef CONFIG_DM_SPI
102 	struct udevice *dev;	/* struct spi_slave is dev->parentdata */
103 	uint max_hz;
104 	uint speed;
105 #else
106 	unsigned int bus;
107 	unsigned int cs;
108 #endif
109 	uint mode;
110 	unsigned int wordlen;
111 	unsigned int max_write_size;
112 	void *memory_map;
113 	u8 option;
114 
115 	u8 flags;
116 #define SPI_XFER_BEGIN		BIT(0)	/* Assert CS before transfer */
117 #define SPI_XFER_END		BIT(1)	/* Deassert CS after transfer */
118 #define SPI_XFER_ONCE		(SPI_XFER_BEGIN | SPI_XFER_END)
119 #define SPI_XFER_MMAP		BIT(2)	/* Memory Mapped start */
120 #define SPI_XFER_MMAP_END	BIT(3)	/* Memory Mapped End */
121 #define SPI_XFER_U_PAGE		BIT(4)
122 };
123 
124 /**
125  * Initialization, must be called once on start up.
126  *
127  * TODO: I don't think we really need this.
128  */
129 void spi_init(void);
130 
131 /**
132  * spi_do_alloc_slave - Allocate a new SPI slave (internal)
133  *
134  * Allocate and zero all fields in the spi slave, and set the bus/chip
135  * select. Use the helper macro spi_alloc_slave() to call this.
136  *
137  * @offset:	Offset of struct spi_slave within slave structure.
138  * @size:	Size of slave structure.
139  * @bus:	Bus ID of the slave chip.
140  * @cs:		Chip select ID of the slave chip on the specified bus.
141  */
142 void *spi_do_alloc_slave(int offset, int size, unsigned int bus,
143 			 unsigned int cs);
144 
145 /**
146  * spi_alloc_slave - Allocate a new SPI slave
147  *
148  * Allocate and zero all fields in the spi slave, and set the bus/chip
149  * select.
150  *
151  * @_struct:	Name of structure to allocate (e.g. struct tegra_spi).
152  *		This structure must contain a member 'struct spi_slave *slave'.
153  * @bus:	Bus ID of the slave chip.
154  * @cs:		Chip select ID of the slave chip on the specified bus.
155  */
156 #define spi_alloc_slave(_struct, bus, cs) \
157 	spi_do_alloc_slave(offsetof(_struct, slave), \
158 			    sizeof(_struct), bus, cs)
159 
160 /**
161  * spi_alloc_slave_base - Allocate a new SPI slave with no private data
162  *
163  * Allocate and zero all fields in the spi slave, and set the bus/chip
164  * select.
165  *
166  * @bus:	Bus ID of the slave chip.
167  * @cs:		Chip select ID of the slave chip on the specified bus.
168  */
169 #define spi_alloc_slave_base(bus, cs) \
170 	spi_do_alloc_slave(0, sizeof(struct spi_slave), bus, cs)
171 
172 /**
173  * Set up communications parameters for a SPI slave.
174  *
175  * This must be called once for each slave. Note that this function
176  * usually doesn't touch any actual hardware, it only initializes the
177  * contents of spi_slave so that the hardware can be easily
178  * initialized later.
179  *
180  * @bus:	Bus ID of the slave chip.
181  * @cs:		Chip select ID of the slave chip on the specified bus.
182  * @max_hz:	Maximum SCK rate in Hz.
183  * @mode:	Clock polarity, clock phase and other parameters.
184  *
185  * Returns: A spi_slave reference that can be used in subsequent SPI
186  * calls, or NULL if one or more of the parameters are not supported.
187  */
188 struct spi_slave *spi_setup_slave(unsigned int bus, unsigned int cs,
189 		unsigned int max_hz, unsigned int mode);
190 
191 /**
192  * Free any memory associated with a SPI slave.
193  *
194  * @slave:	The SPI slave
195  */
196 void spi_free_slave(struct spi_slave *slave);
197 
198 /**
199  * Claim the bus and prepare it for communication with a given slave.
200  *
201  * This must be called before doing any transfers with a SPI slave. It
202  * will enable and initialize any SPI hardware as necessary, and make
203  * sure that the SCK line is in the correct idle state. It is not
204  * allowed to claim the same bus for several slaves without releasing
205  * the bus in between.
206  *
207  * @slave:	The SPI slave
208  *
209  * Returns: 0 if the bus was claimed successfully, or a negative value
210  * if it wasn't.
211  */
212 int spi_claim_bus(struct spi_slave *slave);
213 
214 /**
215  * Release the SPI bus
216  *
217  * This must be called once for every call to spi_claim_bus() after
218  * all transfers have finished. It may disable any SPI hardware as
219  * appropriate.
220  *
221  * @slave:	The SPI slave
222  */
223 void spi_release_bus(struct spi_slave *slave);
224 
225 /**
226  * Set the word length for SPI transactions
227  *
228  * Set the word length (number of bits per word) for SPI transactions.
229  *
230  * @slave:	The SPI slave
231  * @wordlen:	The number of bits in a word
232  *
233  * Returns: 0 on success, -1 on failure.
234  */
235 int spi_set_wordlen(struct spi_slave *slave, unsigned int wordlen);
236 
237 /**
238  * SPI transfer
239  *
240  * This writes "bitlen" bits out the SPI MOSI port and simultaneously clocks
241  * "bitlen" bits in the SPI MISO port.  That's just the way SPI works.
242  *
243  * The source of the outgoing bits is the "dout" parameter and the
244  * destination of the input bits is the "din" parameter.  Note that "dout"
245  * and "din" can point to the same memory location, in which case the
246  * input data overwrites the output data (since both are buffered by
247  * temporary variables, this is OK).
248  *
249  * spi_xfer() interface:
250  * @slave:	The SPI slave which will be sending/receiving the data.
251  * @bitlen:	How many bits to write and read.
252  * @dout:	Pointer to a string of bits to send out.  The bits are
253  *		held in a byte array and are sent MSB first.
254  * @din:	Pointer to a string of bits that will be filled in.
255  * @flags:	A bitwise combination of SPI_XFER_* flags.
256  *
257  * Returns: 0 on success, not 0 on failure
258  */
259 int  spi_xfer(struct spi_slave *slave, unsigned int bitlen, const void *dout,
260 		void *din, unsigned long flags);
261 
262 /* Copy memory mapped data */
263 void spi_flash_copy_mmap(void *data, void *offset, size_t len);
264 
265 /**
266  * Determine if a SPI chipselect is valid.
267  * This function is provided by the board if the low-level SPI driver
268  * needs it to determine if a given chipselect is actually valid.
269  *
270  * Returns: 1 if bus:cs identifies a valid chip on this board, 0
271  * otherwise.
272  */
273 int spi_cs_is_valid(unsigned int bus, unsigned int cs);
274 
275 #ifndef CONFIG_DM_SPI
276 /**
277  * Activate a SPI chipselect.
278  * This function is provided by the board code when using a driver
279  * that can't control its chipselects automatically (e.g.
280  * common/soft_spi.c). When called, it should activate the chip select
281  * to the device identified by "slave".
282  */
283 void spi_cs_activate(struct spi_slave *slave);
284 
285 /**
286  * Deactivate a SPI chipselect.
287  * This function is provided by the board code when using a driver
288  * that can't control its chipselects automatically (e.g.
289  * common/soft_spi.c). When called, it should deactivate the chip
290  * select to the device identified by "slave".
291  */
292 void spi_cs_deactivate(struct spi_slave *slave);
293 
294 /**
295  * Set transfer speed.
296  * This sets a new speed to be applied for next spi_xfer().
297  * @slave:	The SPI slave
298  * @hz:		The transfer speed
299  */
300 void spi_set_speed(struct spi_slave *slave, uint hz);
301 #endif
302 
303 /**
304  * Write 8 bits, then read 8 bits.
305  * @slave:	The SPI slave we're communicating with
306  * @byte:	Byte to be written
307  *
308  * Returns: The value that was read, or a negative value on error.
309  *
310  * TODO: This function probably shouldn't be inlined.
311  */
312 static inline int spi_w8r8(struct spi_slave *slave, unsigned char byte)
313 {
314 	unsigned char dout[2];
315 	unsigned char din[2];
316 	int ret;
317 
318 	dout[0] = byte;
319 	dout[1] = 0;
320 
321 	ret = spi_xfer(slave, 16, dout, din, SPI_XFER_BEGIN | SPI_XFER_END);
322 	return ret < 0 ? ret : din[1];
323 }
324 
325 /**
326  * Set up a SPI slave for a particular device tree node
327  *
328  * This calls spi_setup_slave() with the correct bus number. Call
329  * spi_free_slave() to free it later.
330  *
331  * @param blob:		Device tree blob
332  * @param slave_node:	Slave node to use
333  * @param spi_node:	SPI peripheral node to use
334  * @return pointer to new spi_slave structure
335  */
336 struct spi_slave *spi_setup_slave_fdt(const void *blob, int slave_node,
337 				      int spi_node);
338 
339 /**
340  * spi_base_setup_slave_fdt() - helper function to set up a SPI slace
341  *
342  * This decodes SPI properties from the slave node to determine the
343  * chip select and SPI parameters.
344  *
345  * @blob:	Device tree blob
346  * @busnum:	Bus number to use
347  * @node:	Device tree node for the SPI bus
348  */
349 struct spi_slave *spi_base_setup_slave_fdt(const void *blob, int busnum,
350 					   int node);
351 
352 #ifdef CONFIG_DM_SPI
353 
354 /**
355  * struct spi_cs_info - Information about a bus chip select
356  *
357  * @dev:	Connected device, or NULL if none
358  */
359 struct spi_cs_info {
360 	struct udevice *dev;
361 };
362 
363 /**
364  * struct struct dm_spi_ops - Driver model SPI operations
365  *
366  * The uclass interface is implemented by all SPI devices which use
367  * driver model.
368  */
369 struct dm_spi_ops {
370 	/**
371 	 * Claim the bus and prepare it for communication.
372 	 *
373 	 * The device provided is the slave device. It's parent controller
374 	 * will be used to provide the communication.
375 	 *
376 	 * This must be called before doing any transfers with a SPI slave. It
377 	 * will enable and initialize any SPI hardware as necessary, and make
378 	 * sure that the SCK line is in the correct idle state. It is not
379 	 * allowed to claim the same bus for several slaves without releasing
380 	 * the bus in between.
381 	 *
382 	 * @dev:	The SPI slave
383 	 *
384 	 * Returns: 0 if the bus was claimed successfully, or a negative value
385 	 * if it wasn't.
386 	 */
387 	int (*claim_bus)(struct udevice *dev);
388 
389 	/**
390 	 * Release the SPI bus
391 	 *
392 	 * This must be called once for every call to spi_claim_bus() after
393 	 * all transfers have finished. It may disable any SPI hardware as
394 	 * appropriate.
395 	 *
396 	 * @dev:	The SPI slave
397 	 */
398 	int (*release_bus)(struct udevice *dev);
399 
400 	/**
401 	 * Set the word length for SPI transactions
402 	 *
403 	 * Set the word length (number of bits per word) for SPI transactions.
404 	 *
405 	 * @bus:	The SPI slave
406 	 * @wordlen:	The number of bits in a word
407 	 *
408 	 * Returns: 0 on success, -ve on failure.
409 	 */
410 	int (*set_wordlen)(struct udevice *dev, unsigned int wordlen);
411 
412 	/**
413 	 * SPI transfer
414 	 *
415 	 * This writes "bitlen" bits out the SPI MOSI port and simultaneously
416 	 * clocks "bitlen" bits in the SPI MISO port.  That's just the way SPI
417 	 * works.
418 	 *
419 	 * The source of the outgoing bits is the "dout" parameter and the
420 	 * destination of the input bits is the "din" parameter.  Note that
421 	 * "dout" and "din" can point to the same memory location, in which
422 	 * case the input data overwrites the output data (since both are
423 	 * buffered by temporary variables, this is OK).
424 	 *
425 	 * spi_xfer() interface:
426 	 * @dev:	The slave device to communicate with
427 	 * @bitlen:	How many bits to write and read.
428 	 * @dout:	Pointer to a string of bits to send out.  The bits are
429 	 *		held in a byte array and are sent MSB first.
430 	 * @din:	Pointer to a string of bits that will be filled in.
431 	 * @flags:	A bitwise combination of SPI_XFER_* flags.
432 	 *
433 	 * Returns: 0 on success, not -1 on failure
434 	 */
435 	int (*xfer)(struct udevice *dev, unsigned int bitlen, const void *dout,
436 		    void *din, unsigned long flags);
437 
438 	/**
439 	 * Set transfer speed.
440 	 * This sets a new speed to be applied for next spi_xfer().
441 	 * @bus:	The SPI bus
442 	 * @hz:		The transfer speed
443 	 * @return 0 if OK, -ve on error
444 	 */
445 	int (*set_speed)(struct udevice *bus, uint hz);
446 
447 	/**
448 	 * Set the SPI mode/flags
449 	 *
450 	 * It is unclear if we want to set speed and mode together instead
451 	 * of separately.
452 	 *
453 	 * @bus:	The SPI bus
454 	 * @mode:	Requested SPI mode (SPI_... flags)
455 	 * @return 0 if OK, -ve on error
456 	 */
457 	int (*set_mode)(struct udevice *bus, uint mode);
458 
459 	/**
460 	 * Get information on a chip select
461 	 *
462 	 * This is only called when the SPI uclass does not know about a
463 	 * chip select, i.e. it has no attached device. It gives the driver
464 	 * a chance to allow activity on that chip select even so.
465 	 *
466 	 * @bus:	The SPI bus
467 	 * @cs:		The chip select (0..n-1)
468 	 * @info:	Returns information about the chip select, if valid.
469 	 *		On entry info->dev is NULL
470 	 * @return 0 if OK (and @info is set up), -ENODEV if the chip select
471 	 *	   is invalid, other -ve value on error
472 	 */
473 	int (*cs_info)(struct udevice *bus, uint cs, struct spi_cs_info *info);
474 };
475 
476 struct dm_spi_emul_ops {
477 	/**
478 	 * SPI transfer
479 	 *
480 	 * This writes "bitlen" bits out the SPI MOSI port and simultaneously
481 	 * clocks "bitlen" bits in the SPI MISO port.  That's just the way SPI
482 	 * works. Here the device is a slave.
483 	 *
484 	 * The source of the outgoing bits is the "dout" parameter and the
485 	 * destination of the input bits is the "din" parameter.  Note that
486 	 * "dout" and "din" can point to the same memory location, in which
487 	 * case the input data overwrites the output data (since both are
488 	 * buffered by temporary variables, this is OK).
489 	 *
490 	 * spi_xfer() interface:
491 	 * @slave:	The SPI slave which will be sending/receiving the data.
492 	 * @bitlen:	How many bits to write and read.
493 	 * @dout:	Pointer to a string of bits sent to the device. The
494 	 *		bits are held in a byte array and are sent MSB first.
495 	 * @din:	Pointer to a string of bits that will be sent back to
496 	 *		the master.
497 	 * @flags:	A bitwise combination of SPI_XFER_* flags.
498 	 *
499 	 * Returns: 0 on success, not -1 on failure
500 	 */
501 	int (*xfer)(struct udevice *slave, unsigned int bitlen,
502 		    const void *dout, void *din, unsigned long flags);
503 };
504 
505 /**
506  * spi_find_bus_and_cs() - Find bus and slave devices by number
507  *
508  * Given a bus number and chip select, this finds the corresponding bus
509  * device and slave device. Neither device is activated by this function,
510  * although they may have been activated previously.
511  *
512  * @busnum:	SPI bus number
513  * @cs:		Chip select to look for
514  * @busp:	Returns bus device
515  * @devp:	Return slave device
516  * @return 0 if found, -ENODEV on error
517  */
518 int spi_find_bus_and_cs(int busnum, int cs, struct udevice **busp,
519 			struct udevice **devp);
520 
521 /**
522  * spi_get_bus_and_cs() - Find and activate bus and slave devices by number
523  *
524  * Given a bus number and chip select, this finds the corresponding bus
525  * device and slave device.
526  *
527  * If no such slave exists, and drv_name is not NULL, then a new slave device
528  * is automatically bound on this chip select.
529  *
530  * Ths new slave device is probed ready for use with the given speed and mode.
531  *
532  * @busnum:	SPI bus number
533  * @cs:		Chip select to look for
534  * @speed:	SPI speed to use for this slave
535  * @mode:	SPI mode to use for this slave
536  * @drv_name:	Name of driver to attach to this chip select
537  * @dev_name:	Name of the new device thus created
538  * @busp:	Returns bus device
539  * @devp:	Return slave device
540  * @return 0 if found, -ve on error
541  */
542 int spi_get_bus_and_cs(int busnum, int cs, int speed, int mode,
543 			const char *drv_name, const char *dev_name,
544 			struct udevice **busp, struct spi_slave **devp);
545 
546 /**
547  * spi_chip_select() - Get the chip select for a slave
548  *
549  * @return the chip select this slave is attached to
550  */
551 int spi_chip_select(struct udevice *slave);
552 
553 /**
554  * spi_find_chip_select() - Find the slave attached to chip select
555  *
556  * @bus:	SPI bus to search
557  * @cs:		Chip select to look for
558  * @devp:	Returns the slave device if found
559  * @return 0 if found, -ENODEV on error
560  */
561 int spi_find_chip_select(struct udevice *bus, int cs, struct udevice **devp);
562 
563 /**
564  * spi_slave_ofdata_to_platdata() - decode standard SPI platform data
565  *
566  * This decodes the speed and mode for a slave from a device tree node
567  *
568  * @blob:	Device tree blob
569  * @node:	Node offset to read from
570  * @plat:	Place to put the decoded information
571  */
572 int spi_slave_ofdata_to_platdata(const void *blob, int node,
573 				 struct dm_spi_slave_platdata *plat);
574 
575 /**
576  * spi_cs_info() - Check information on a chip select
577  *
578  * This checks a particular chip select on a bus to see if it has a device
579  * attached, or is even valid.
580  *
581  * @bus:	The SPI bus
582  * @cs:		The chip select (0..n-1)
583  * @info:	Returns information about the chip select, if valid
584  * @return 0 if OK (and @info is set up), -ENODEV if the chip select
585  *	   is invalid, other -ve value on error
586  */
587 int spi_cs_info(struct udevice *bus, uint cs, struct spi_cs_info *info);
588 
589 struct sandbox_state;
590 
591 /**
592  * sandbox_spi_get_emul() - get an emulator for a SPI slave
593  *
594  * This provides a way to attach an emulated SPI device to a particular SPI
595  * slave, so that xfer() operations on the slave will be handled by the
596  * emulator. If a emulator already exists on that chip select it is returned.
597  * Otherwise one is created.
598  *
599  * @state:	Sandbox state
600  * @bus:	SPI bus requesting the emulator
601  * @slave:	SPI slave device requesting the emulator
602  * @emuip:	Returns pointer to emulator
603  * @return 0 if OK, -ve on error
604  */
605 int sandbox_spi_get_emul(struct sandbox_state *state,
606 			 struct udevice *bus, struct udevice *slave,
607 			 struct udevice **emulp);
608 
609 /**
610  * Claim the bus and prepare it for communication with a given slave.
611  *
612  * This must be called before doing any transfers with a SPI slave. It
613  * will enable and initialize any SPI hardware as necessary, and make
614  * sure that the SCK line is in the correct idle state. It is not
615  * allowed to claim the same bus for several slaves without releasing
616  * the bus in between.
617  *
618  * @dev:	The SPI slave device
619  *
620  * Returns: 0 if the bus was claimed successfully, or a negative value
621  * if it wasn't.
622  */
623 int dm_spi_claim_bus(struct udevice *dev);
624 
625 /**
626  * Release the SPI bus
627  *
628  * This must be called once for every call to dm_spi_claim_bus() after
629  * all transfers have finished. It may disable any SPI hardware as
630  * appropriate.
631  *
632  * @slave:	The SPI slave device
633  */
634 void dm_spi_release_bus(struct udevice *dev);
635 
636 /**
637  * SPI transfer
638  *
639  * This writes "bitlen" bits out the SPI MOSI port and simultaneously clocks
640  * "bitlen" bits in the SPI MISO port.  That's just the way SPI works.
641  *
642  * The source of the outgoing bits is the "dout" parameter and the
643  * destination of the input bits is the "din" parameter.  Note that "dout"
644  * and "din" can point to the same memory location, in which case the
645  * input data overwrites the output data (since both are buffered by
646  * temporary variables, this is OK).
647  *
648  * dm_spi_xfer() interface:
649  * @dev:	The SPI slave device which will be sending/receiving the data.
650  * @bitlen:	How many bits to write and read.
651  * @dout:	Pointer to a string of bits to send out.  The bits are
652  *		held in a byte array and are sent MSB first.
653  * @din:	Pointer to a string of bits that will be filled in.
654  * @flags:	A bitwise combination of SPI_XFER_* flags.
655  *
656  * Returns: 0 on success, not 0 on failure
657  */
658 int dm_spi_xfer(struct udevice *dev, unsigned int bitlen,
659 		const void *dout, void *din, unsigned long flags);
660 
661 /* Access the operations for a SPI device */
662 #define spi_get_ops(dev)	((struct dm_spi_ops *)(dev)->driver->ops)
663 #define spi_emul_get_ops(dev)	((struct dm_spi_emul_ops *)(dev)->driver->ops)
664 #endif /* CONFIG_DM_SPI */
665 
666 #endif	/* _SPI_H_ */
667