xref: /openbmc/linux/drivers/spi/spi-mem.c (revision b4e18b29)
1 // SPDX-License-Identifier: GPL-2.0+
2 /*
3  * Copyright (C) 2018 Exceet Electronics GmbH
4  * Copyright (C) 2018 Bootlin
5  *
6  * Author: Boris Brezillon <boris.brezillon@bootlin.com>
7  */
8 #include <linux/dmaengine.h>
9 #include <linux/pm_runtime.h>
10 #include <linux/spi/spi.h>
11 #include <linux/spi/spi-mem.h>
12 
13 #include "internals.h"
14 
15 #define SPI_MEM_MAX_BUSWIDTH		8
16 
17 /**
18  * spi_controller_dma_map_mem_op_data() - DMA-map the buffer attached to a
19  *					  memory operation
20  * @ctlr: the SPI controller requesting this dma_map()
21  * @op: the memory operation containing the buffer to map
22  * @sgt: a pointer to a non-initialized sg_table that will be filled by this
23  *	 function
24  *
25  * Some controllers might want to do DMA on the data buffer embedded in @op.
26  * This helper prepares everything for you and provides a ready-to-use
27  * sg_table. This function is not intended to be called from spi drivers.
28  * Only SPI controller drivers should use it.
29  * Note that the caller must ensure the memory region pointed by
30  * op->data.buf.{in,out} is DMA-able before calling this function.
31  *
32  * Return: 0 in case of success, a negative error code otherwise.
33  */
34 int spi_controller_dma_map_mem_op_data(struct spi_controller *ctlr,
35 				       const struct spi_mem_op *op,
36 				       struct sg_table *sgt)
37 {
38 	struct device *dmadev;
39 
40 	if (!op->data.nbytes)
41 		return -EINVAL;
42 
43 	if (op->data.dir == SPI_MEM_DATA_OUT && ctlr->dma_tx)
44 		dmadev = ctlr->dma_tx->device->dev;
45 	else if (op->data.dir == SPI_MEM_DATA_IN && ctlr->dma_rx)
46 		dmadev = ctlr->dma_rx->device->dev;
47 	else
48 		dmadev = ctlr->dev.parent;
49 
50 	if (!dmadev)
51 		return -EINVAL;
52 
53 	return spi_map_buf(ctlr, dmadev, sgt, op->data.buf.in, op->data.nbytes,
54 			   op->data.dir == SPI_MEM_DATA_IN ?
55 			   DMA_FROM_DEVICE : DMA_TO_DEVICE);
56 }
57 EXPORT_SYMBOL_GPL(spi_controller_dma_map_mem_op_data);
58 
59 /**
60  * spi_controller_dma_unmap_mem_op_data() - DMA-unmap the buffer attached to a
61  *					    memory operation
62  * @ctlr: the SPI controller requesting this dma_unmap()
63  * @op: the memory operation containing the buffer to unmap
64  * @sgt: a pointer to an sg_table previously initialized by
65  *	 spi_controller_dma_map_mem_op_data()
66  *
67  * Some controllers might want to do DMA on the data buffer embedded in @op.
68  * This helper prepares things so that the CPU can access the
69  * op->data.buf.{in,out} buffer again.
70  *
71  * This function is not intended to be called from SPI drivers. Only SPI
72  * controller drivers should use it.
73  *
74  * This function should be called after the DMA operation has finished and is
75  * only valid if the previous spi_controller_dma_map_mem_op_data() call
76  * returned 0.
77  *
78  * Return: 0 in case of success, a negative error code otherwise.
79  */
80 void spi_controller_dma_unmap_mem_op_data(struct spi_controller *ctlr,
81 					  const struct spi_mem_op *op,
82 					  struct sg_table *sgt)
83 {
84 	struct device *dmadev;
85 
86 	if (!op->data.nbytes)
87 		return;
88 
89 	if (op->data.dir == SPI_MEM_DATA_OUT && ctlr->dma_tx)
90 		dmadev = ctlr->dma_tx->device->dev;
91 	else if (op->data.dir == SPI_MEM_DATA_IN && ctlr->dma_rx)
92 		dmadev = ctlr->dma_rx->device->dev;
93 	else
94 		dmadev = ctlr->dev.parent;
95 
96 	spi_unmap_buf(ctlr, dmadev, sgt,
97 		      op->data.dir == SPI_MEM_DATA_IN ?
98 		      DMA_FROM_DEVICE : DMA_TO_DEVICE);
99 }
100 EXPORT_SYMBOL_GPL(spi_controller_dma_unmap_mem_op_data);
101 
102 static int spi_check_buswidth_req(struct spi_mem *mem, u8 buswidth, bool tx)
103 {
104 	u32 mode = mem->spi->mode;
105 
106 	switch (buswidth) {
107 	case 1:
108 		return 0;
109 
110 	case 2:
111 		if ((tx &&
112 		     (mode & (SPI_TX_DUAL | SPI_TX_QUAD | SPI_TX_OCTAL))) ||
113 		    (!tx &&
114 		     (mode & (SPI_RX_DUAL | SPI_RX_QUAD | SPI_RX_OCTAL))))
115 			return 0;
116 
117 		break;
118 
119 	case 4:
120 		if ((tx && (mode & (SPI_TX_QUAD | SPI_TX_OCTAL))) ||
121 		    (!tx && (mode & (SPI_RX_QUAD | SPI_RX_OCTAL))))
122 			return 0;
123 
124 		break;
125 
126 	case 8:
127 		if ((tx && (mode & SPI_TX_OCTAL)) ||
128 		    (!tx && (mode & SPI_RX_OCTAL)))
129 			return 0;
130 
131 		break;
132 
133 	default:
134 		break;
135 	}
136 
137 	return -ENOTSUPP;
138 }
139 
140 bool spi_mem_default_supports_op(struct spi_mem *mem,
141 				 const struct spi_mem_op *op)
142 {
143 	if (spi_check_buswidth_req(mem, op->cmd.buswidth, true))
144 		return false;
145 
146 	if (op->addr.nbytes &&
147 	    spi_check_buswidth_req(mem, op->addr.buswidth, true))
148 		return false;
149 
150 	if (op->dummy.nbytes &&
151 	    spi_check_buswidth_req(mem, op->dummy.buswidth, true))
152 		return false;
153 
154 	if (op->data.dir != SPI_MEM_NO_DATA &&
155 	    spi_check_buswidth_req(mem, op->data.buswidth,
156 				   op->data.dir == SPI_MEM_DATA_OUT))
157 		return false;
158 
159 	if (op->cmd.dtr || op->addr.dtr || op->dummy.dtr || op->data.dtr)
160 		return false;
161 
162 	if (op->cmd.nbytes != 1)
163 		return false;
164 
165 	return true;
166 }
167 EXPORT_SYMBOL_GPL(spi_mem_default_supports_op);
168 
169 static bool spi_mem_buswidth_is_valid(u8 buswidth)
170 {
171 	if (hweight8(buswidth) > 1 || buswidth > SPI_MEM_MAX_BUSWIDTH)
172 		return false;
173 
174 	return true;
175 }
176 
177 static int spi_mem_check_op(const struct spi_mem_op *op)
178 {
179 	if (!op->cmd.buswidth || !op->cmd.nbytes)
180 		return -EINVAL;
181 
182 	if ((op->addr.nbytes && !op->addr.buswidth) ||
183 	    (op->dummy.nbytes && !op->dummy.buswidth) ||
184 	    (op->data.nbytes && !op->data.buswidth))
185 		return -EINVAL;
186 
187 	if (!spi_mem_buswidth_is_valid(op->cmd.buswidth) ||
188 	    !spi_mem_buswidth_is_valid(op->addr.buswidth) ||
189 	    !spi_mem_buswidth_is_valid(op->dummy.buswidth) ||
190 	    !spi_mem_buswidth_is_valid(op->data.buswidth))
191 		return -EINVAL;
192 
193 	return 0;
194 }
195 
196 static bool spi_mem_internal_supports_op(struct spi_mem *mem,
197 					 const struct spi_mem_op *op)
198 {
199 	struct spi_controller *ctlr = mem->spi->controller;
200 
201 	if (ctlr->mem_ops && ctlr->mem_ops->supports_op)
202 		return ctlr->mem_ops->supports_op(mem, op);
203 
204 	return spi_mem_default_supports_op(mem, op);
205 }
206 
207 /**
208  * spi_mem_supports_op() - Check if a memory device and the controller it is
209  *			   connected to support a specific memory operation
210  * @mem: the SPI memory
211  * @op: the memory operation to check
212  *
213  * Some controllers are only supporting Single or Dual IOs, others might only
214  * support specific opcodes, or it can even be that the controller and device
215  * both support Quad IOs but the hardware prevents you from using it because
216  * only 2 IO lines are connected.
217  *
218  * This function checks whether a specific operation is supported.
219  *
220  * Return: true if @op is supported, false otherwise.
221  */
222 bool spi_mem_supports_op(struct spi_mem *mem, const struct spi_mem_op *op)
223 {
224 	if (spi_mem_check_op(op))
225 		return false;
226 
227 	return spi_mem_internal_supports_op(mem, op);
228 }
229 EXPORT_SYMBOL_GPL(spi_mem_supports_op);
230 
231 static int spi_mem_access_start(struct spi_mem *mem)
232 {
233 	struct spi_controller *ctlr = mem->spi->controller;
234 
235 	/*
236 	 * Flush the message queue before executing our SPI memory
237 	 * operation to prevent preemption of regular SPI transfers.
238 	 */
239 	spi_flush_queue(ctlr);
240 
241 	if (ctlr->auto_runtime_pm) {
242 		int ret;
243 
244 		ret = pm_runtime_get_sync(ctlr->dev.parent);
245 		if (ret < 0) {
246 			pm_runtime_put_noidle(ctlr->dev.parent);
247 			dev_err(&ctlr->dev, "Failed to power device: %d\n",
248 				ret);
249 			return ret;
250 		}
251 	}
252 
253 	mutex_lock(&ctlr->bus_lock_mutex);
254 	mutex_lock(&ctlr->io_mutex);
255 
256 	return 0;
257 }
258 
259 static void spi_mem_access_end(struct spi_mem *mem)
260 {
261 	struct spi_controller *ctlr = mem->spi->controller;
262 
263 	mutex_unlock(&ctlr->io_mutex);
264 	mutex_unlock(&ctlr->bus_lock_mutex);
265 
266 	if (ctlr->auto_runtime_pm)
267 		pm_runtime_put(ctlr->dev.parent);
268 }
269 
270 /**
271  * spi_mem_exec_op() - Execute a memory operation
272  * @mem: the SPI memory
273  * @op: the memory operation to execute
274  *
275  * Executes a memory operation.
276  *
277  * This function first checks that @op is supported and then tries to execute
278  * it.
279  *
280  * Return: 0 in case of success, a negative error code otherwise.
281  */
282 int spi_mem_exec_op(struct spi_mem *mem, const struct spi_mem_op *op)
283 {
284 	unsigned int tmpbufsize, xferpos = 0, totalxferlen = 0;
285 	struct spi_controller *ctlr = mem->spi->controller;
286 	struct spi_transfer xfers[4] = { };
287 	struct spi_message msg;
288 	u8 *tmpbuf;
289 	int ret;
290 
291 	ret = spi_mem_check_op(op);
292 	if (ret)
293 		return ret;
294 
295 	if (!spi_mem_internal_supports_op(mem, op))
296 		return -ENOTSUPP;
297 
298 	if (ctlr->mem_ops && !mem->spi->cs_gpiod) {
299 		ret = spi_mem_access_start(mem);
300 		if (ret)
301 			return ret;
302 
303 		ret = ctlr->mem_ops->exec_op(mem, op);
304 
305 		spi_mem_access_end(mem);
306 
307 		/*
308 		 * Some controllers only optimize specific paths (typically the
309 		 * read path) and expect the core to use the regular SPI
310 		 * interface in other cases.
311 		 */
312 		if (!ret || ret != -ENOTSUPP)
313 			return ret;
314 	}
315 
316 	tmpbufsize = op->cmd.nbytes + op->addr.nbytes + op->dummy.nbytes;
317 
318 	/*
319 	 * Allocate a buffer to transmit the CMD, ADDR cycles with kmalloc() so
320 	 * we're guaranteed that this buffer is DMA-able, as required by the
321 	 * SPI layer.
322 	 */
323 	tmpbuf = kzalloc(tmpbufsize, GFP_KERNEL | GFP_DMA);
324 	if (!tmpbuf)
325 		return -ENOMEM;
326 
327 	spi_message_init(&msg);
328 
329 	tmpbuf[0] = op->cmd.opcode;
330 	xfers[xferpos].tx_buf = tmpbuf;
331 	xfers[xferpos].len = op->cmd.nbytes;
332 	xfers[xferpos].tx_nbits = op->cmd.buswidth;
333 	spi_message_add_tail(&xfers[xferpos], &msg);
334 	xferpos++;
335 	totalxferlen++;
336 
337 	if (op->addr.nbytes) {
338 		int i;
339 
340 		for (i = 0; i < op->addr.nbytes; i++)
341 			tmpbuf[i + 1] = op->addr.val >>
342 					(8 * (op->addr.nbytes - i - 1));
343 
344 		xfers[xferpos].tx_buf = tmpbuf + 1;
345 		xfers[xferpos].len = op->addr.nbytes;
346 		xfers[xferpos].tx_nbits = op->addr.buswidth;
347 		spi_message_add_tail(&xfers[xferpos], &msg);
348 		xferpos++;
349 		totalxferlen += op->addr.nbytes;
350 	}
351 
352 	if (op->dummy.nbytes) {
353 		memset(tmpbuf + op->addr.nbytes + 1, 0xff, op->dummy.nbytes);
354 		xfers[xferpos].tx_buf = tmpbuf + op->addr.nbytes + 1;
355 		xfers[xferpos].len = op->dummy.nbytes;
356 		xfers[xferpos].tx_nbits = op->dummy.buswidth;
357 		spi_message_add_tail(&xfers[xferpos], &msg);
358 		xferpos++;
359 		totalxferlen += op->dummy.nbytes;
360 	}
361 
362 	if (op->data.nbytes) {
363 		if (op->data.dir == SPI_MEM_DATA_IN) {
364 			xfers[xferpos].rx_buf = op->data.buf.in;
365 			xfers[xferpos].rx_nbits = op->data.buswidth;
366 		} else {
367 			xfers[xferpos].tx_buf = op->data.buf.out;
368 			xfers[xferpos].tx_nbits = op->data.buswidth;
369 		}
370 
371 		xfers[xferpos].len = op->data.nbytes;
372 		spi_message_add_tail(&xfers[xferpos], &msg);
373 		xferpos++;
374 		totalxferlen += op->data.nbytes;
375 	}
376 
377 	ret = spi_sync(mem->spi, &msg);
378 
379 	kfree(tmpbuf);
380 
381 	if (ret)
382 		return ret;
383 
384 	if (msg.actual_length != totalxferlen)
385 		return -EIO;
386 
387 	return 0;
388 }
389 EXPORT_SYMBOL_GPL(spi_mem_exec_op);
390 
391 /**
392  * spi_mem_get_name() - Return the SPI mem device name to be used by the
393  *			upper layer if necessary
394  * @mem: the SPI memory
395  *
396  * This function allows SPI mem users to retrieve the SPI mem device name.
397  * It is useful if the upper layer needs to expose a custom name for
398  * compatibility reasons.
399  *
400  * Return: a string containing the name of the memory device to be used
401  *	   by the SPI mem user
402  */
403 const char *spi_mem_get_name(struct spi_mem *mem)
404 {
405 	return mem->name;
406 }
407 EXPORT_SYMBOL_GPL(spi_mem_get_name);
408 
409 /**
410  * spi_mem_adjust_op_size() - Adjust the data size of a SPI mem operation to
411  *			      match controller limitations
412  * @mem: the SPI memory
413  * @op: the operation to adjust
414  *
415  * Some controllers have FIFO limitations and must split a data transfer
416  * operation into multiple ones, others require a specific alignment for
417  * optimized accesses. This function allows SPI mem drivers to split a single
418  * operation into multiple sub-operations when required.
419  *
420  * Return: a negative error code if the controller can't properly adjust @op,
421  *	   0 otherwise. Note that @op->data.nbytes will be updated if @op
422  *	   can't be handled in a single step.
423  */
424 int spi_mem_adjust_op_size(struct spi_mem *mem, struct spi_mem_op *op)
425 {
426 	struct spi_controller *ctlr = mem->spi->controller;
427 	size_t len;
428 
429 	if (ctlr->mem_ops && ctlr->mem_ops->adjust_op_size)
430 		return ctlr->mem_ops->adjust_op_size(mem, op);
431 
432 	if (!ctlr->mem_ops || !ctlr->mem_ops->exec_op) {
433 		len = op->cmd.nbytes + op->addr.nbytes + op->dummy.nbytes;
434 
435 		if (len > spi_max_transfer_size(mem->spi))
436 			return -EINVAL;
437 
438 		op->data.nbytes = min3((size_t)op->data.nbytes,
439 				       spi_max_transfer_size(mem->spi),
440 				       spi_max_message_size(mem->spi) -
441 				       len);
442 		if (!op->data.nbytes)
443 			return -EINVAL;
444 	}
445 
446 	return 0;
447 }
448 EXPORT_SYMBOL_GPL(spi_mem_adjust_op_size);
449 
450 static ssize_t spi_mem_no_dirmap_read(struct spi_mem_dirmap_desc *desc,
451 				      u64 offs, size_t len, void *buf)
452 {
453 	struct spi_mem_op op = desc->info.op_tmpl;
454 	int ret;
455 
456 	op.addr.val = desc->info.offset + offs;
457 	op.data.buf.in = buf;
458 	op.data.nbytes = len;
459 	ret = spi_mem_adjust_op_size(desc->mem, &op);
460 	if (ret)
461 		return ret;
462 
463 	ret = spi_mem_exec_op(desc->mem, &op);
464 	if (ret)
465 		return ret;
466 
467 	return op.data.nbytes;
468 }
469 
470 static ssize_t spi_mem_no_dirmap_write(struct spi_mem_dirmap_desc *desc,
471 				       u64 offs, size_t len, const void *buf)
472 {
473 	struct spi_mem_op op = desc->info.op_tmpl;
474 	int ret;
475 
476 	op.addr.val = desc->info.offset + offs;
477 	op.data.buf.out = buf;
478 	op.data.nbytes = len;
479 	ret = spi_mem_adjust_op_size(desc->mem, &op);
480 	if (ret)
481 		return ret;
482 
483 	ret = spi_mem_exec_op(desc->mem, &op);
484 	if (ret)
485 		return ret;
486 
487 	return op.data.nbytes;
488 }
489 
490 /**
491  * spi_mem_dirmap_create() - Create a direct mapping descriptor
492  * @mem: SPI mem device this direct mapping should be created for
493  * @info: direct mapping information
494  *
495  * This function is creating a direct mapping descriptor which can then be used
496  * to access the memory using spi_mem_dirmap_read() or spi_mem_dirmap_write().
497  * If the SPI controller driver does not support direct mapping, this function
498  * falls back to an implementation using spi_mem_exec_op(), so that the caller
499  * doesn't have to bother implementing a fallback on his own.
500  *
501  * Return: a valid pointer in case of success, and ERR_PTR() otherwise.
502  */
503 struct spi_mem_dirmap_desc *
504 spi_mem_dirmap_create(struct spi_mem *mem,
505 		      const struct spi_mem_dirmap_info *info)
506 {
507 	struct spi_controller *ctlr = mem->spi->controller;
508 	struct spi_mem_dirmap_desc *desc;
509 	int ret = -ENOTSUPP;
510 
511 	/* Make sure the number of address cycles is between 1 and 8 bytes. */
512 	if (!info->op_tmpl.addr.nbytes || info->op_tmpl.addr.nbytes > 8)
513 		return ERR_PTR(-EINVAL);
514 
515 	/* data.dir should either be SPI_MEM_DATA_IN or SPI_MEM_DATA_OUT. */
516 	if (info->op_tmpl.data.dir == SPI_MEM_NO_DATA)
517 		return ERR_PTR(-EINVAL);
518 
519 	desc = kzalloc(sizeof(*desc), GFP_KERNEL);
520 	if (!desc)
521 		return ERR_PTR(-ENOMEM);
522 
523 	desc->mem = mem;
524 	desc->info = *info;
525 	if (ctlr->mem_ops && ctlr->mem_ops->dirmap_create)
526 		ret = ctlr->mem_ops->dirmap_create(desc);
527 
528 	if (ret) {
529 		desc->nodirmap = true;
530 		if (!spi_mem_supports_op(desc->mem, &desc->info.op_tmpl))
531 			ret = -ENOTSUPP;
532 		else
533 			ret = 0;
534 	}
535 
536 	if (ret) {
537 		kfree(desc);
538 		return ERR_PTR(ret);
539 	}
540 
541 	return desc;
542 }
543 EXPORT_SYMBOL_GPL(spi_mem_dirmap_create);
544 
545 /**
546  * spi_mem_dirmap_destroy() - Destroy a direct mapping descriptor
547  * @desc: the direct mapping descriptor to destroy
548  *
549  * This function destroys a direct mapping descriptor previously created by
550  * spi_mem_dirmap_create().
551  */
552 void spi_mem_dirmap_destroy(struct spi_mem_dirmap_desc *desc)
553 {
554 	struct spi_controller *ctlr = desc->mem->spi->controller;
555 
556 	if (!desc->nodirmap && ctlr->mem_ops && ctlr->mem_ops->dirmap_destroy)
557 		ctlr->mem_ops->dirmap_destroy(desc);
558 
559 	kfree(desc);
560 }
561 EXPORT_SYMBOL_GPL(spi_mem_dirmap_destroy);
562 
563 static void devm_spi_mem_dirmap_release(struct device *dev, void *res)
564 {
565 	struct spi_mem_dirmap_desc *desc = *(struct spi_mem_dirmap_desc **)res;
566 
567 	spi_mem_dirmap_destroy(desc);
568 }
569 
570 /**
571  * devm_spi_mem_dirmap_create() - Create a direct mapping descriptor and attach
572  *				  it to a device
573  * @dev: device the dirmap desc will be attached to
574  * @mem: SPI mem device this direct mapping should be created for
575  * @info: direct mapping information
576  *
577  * devm_ variant of the spi_mem_dirmap_create() function. See
578  * spi_mem_dirmap_create() for more details.
579  *
580  * Return: a valid pointer in case of success, and ERR_PTR() otherwise.
581  */
582 struct spi_mem_dirmap_desc *
583 devm_spi_mem_dirmap_create(struct device *dev, struct spi_mem *mem,
584 			   const struct spi_mem_dirmap_info *info)
585 {
586 	struct spi_mem_dirmap_desc **ptr, *desc;
587 
588 	ptr = devres_alloc(devm_spi_mem_dirmap_release, sizeof(*ptr),
589 			   GFP_KERNEL);
590 	if (!ptr)
591 		return ERR_PTR(-ENOMEM);
592 
593 	desc = spi_mem_dirmap_create(mem, info);
594 	if (IS_ERR(desc)) {
595 		devres_free(ptr);
596 	} else {
597 		*ptr = desc;
598 		devres_add(dev, ptr);
599 	}
600 
601 	return desc;
602 }
603 EXPORT_SYMBOL_GPL(devm_spi_mem_dirmap_create);
604 
605 static int devm_spi_mem_dirmap_match(struct device *dev, void *res, void *data)
606 {
607         struct spi_mem_dirmap_desc **ptr = res;
608 
609         if (WARN_ON(!ptr || !*ptr))
610                 return 0;
611 
612 	return *ptr == data;
613 }
614 
615 /**
616  * devm_spi_mem_dirmap_destroy() - Destroy a direct mapping descriptor attached
617  *				   to a device
618  * @dev: device the dirmap desc is attached to
619  * @desc: the direct mapping descriptor to destroy
620  *
621  * devm_ variant of the spi_mem_dirmap_destroy() function. See
622  * spi_mem_dirmap_destroy() for more details.
623  */
624 void devm_spi_mem_dirmap_destroy(struct device *dev,
625 				 struct spi_mem_dirmap_desc *desc)
626 {
627 	devres_release(dev, devm_spi_mem_dirmap_release,
628 		       devm_spi_mem_dirmap_match, desc);
629 }
630 EXPORT_SYMBOL_GPL(devm_spi_mem_dirmap_destroy);
631 
632 /**
633  * spi_mem_dirmap_read() - Read data through a direct mapping
634  * @desc: direct mapping descriptor
635  * @offs: offset to start reading from. Note that this is not an absolute
636  *	  offset, but the offset within the direct mapping which already has
637  *	  its own offset
638  * @len: length in bytes
639  * @buf: destination buffer. This buffer must be DMA-able
640  *
641  * This function reads data from a memory device using a direct mapping
642  * previously instantiated with spi_mem_dirmap_create().
643  *
644  * Return: the amount of data read from the memory device or a negative error
645  * code. Note that the returned size might be smaller than @len, and the caller
646  * is responsible for calling spi_mem_dirmap_read() again when that happens.
647  */
648 ssize_t spi_mem_dirmap_read(struct spi_mem_dirmap_desc *desc,
649 			    u64 offs, size_t len, void *buf)
650 {
651 	struct spi_controller *ctlr = desc->mem->spi->controller;
652 	ssize_t ret;
653 
654 	if (desc->info.op_tmpl.data.dir != SPI_MEM_DATA_IN)
655 		return -EINVAL;
656 
657 	if (!len)
658 		return 0;
659 
660 	if (desc->nodirmap) {
661 		ret = spi_mem_no_dirmap_read(desc, offs, len, buf);
662 	} else if (ctlr->mem_ops && ctlr->mem_ops->dirmap_read) {
663 		ret = spi_mem_access_start(desc->mem);
664 		if (ret)
665 			return ret;
666 
667 		ret = ctlr->mem_ops->dirmap_read(desc, offs, len, buf);
668 
669 		spi_mem_access_end(desc->mem);
670 	} else {
671 		ret = -ENOTSUPP;
672 	}
673 
674 	return ret;
675 }
676 EXPORT_SYMBOL_GPL(spi_mem_dirmap_read);
677 
678 /**
679  * spi_mem_dirmap_write() - Write data through a direct mapping
680  * @desc: direct mapping descriptor
681  * @offs: offset to start writing from. Note that this is not an absolute
682  *	  offset, but the offset within the direct mapping which already has
683  *	  its own offset
684  * @len: length in bytes
685  * @buf: source buffer. This buffer must be DMA-able
686  *
687  * This function writes data to a memory device using a direct mapping
688  * previously instantiated with spi_mem_dirmap_create().
689  *
690  * Return: the amount of data written to the memory device or a negative error
691  * code. Note that the returned size might be smaller than @len, and the caller
692  * is responsible for calling spi_mem_dirmap_write() again when that happens.
693  */
694 ssize_t spi_mem_dirmap_write(struct spi_mem_dirmap_desc *desc,
695 			     u64 offs, size_t len, const void *buf)
696 {
697 	struct spi_controller *ctlr = desc->mem->spi->controller;
698 	ssize_t ret;
699 
700 	if (desc->info.op_tmpl.data.dir != SPI_MEM_DATA_OUT)
701 		return -EINVAL;
702 
703 	if (!len)
704 		return 0;
705 
706 	if (desc->nodirmap) {
707 		ret = spi_mem_no_dirmap_write(desc, offs, len, buf);
708 	} else if (ctlr->mem_ops && ctlr->mem_ops->dirmap_write) {
709 		ret = spi_mem_access_start(desc->mem);
710 		if (ret)
711 			return ret;
712 
713 		ret = ctlr->mem_ops->dirmap_write(desc, offs, len, buf);
714 
715 		spi_mem_access_end(desc->mem);
716 	} else {
717 		ret = -ENOTSUPP;
718 	}
719 
720 	return ret;
721 }
722 EXPORT_SYMBOL_GPL(spi_mem_dirmap_write);
723 
724 static inline struct spi_mem_driver *to_spi_mem_drv(struct device_driver *drv)
725 {
726 	return container_of(drv, struct spi_mem_driver, spidrv.driver);
727 }
728 
729 static int spi_mem_probe(struct spi_device *spi)
730 {
731 	struct spi_mem_driver *memdrv = to_spi_mem_drv(spi->dev.driver);
732 	struct spi_controller *ctlr = spi->controller;
733 	struct spi_mem *mem;
734 
735 	mem = devm_kzalloc(&spi->dev, sizeof(*mem), GFP_KERNEL);
736 	if (!mem)
737 		return -ENOMEM;
738 
739 	mem->spi = spi;
740 
741 	if (ctlr->mem_ops && ctlr->mem_ops->get_name)
742 		mem->name = ctlr->mem_ops->get_name(mem);
743 	else
744 		mem->name = dev_name(&spi->dev);
745 
746 	if (IS_ERR_OR_NULL(mem->name))
747 		return PTR_ERR_OR_ZERO(mem->name);
748 
749 	spi_set_drvdata(spi, mem);
750 
751 	return memdrv->probe(mem);
752 }
753 
754 static int spi_mem_remove(struct spi_device *spi)
755 {
756 	struct spi_mem_driver *memdrv = to_spi_mem_drv(spi->dev.driver);
757 	struct spi_mem *mem = spi_get_drvdata(spi);
758 
759 	if (memdrv->remove)
760 		return memdrv->remove(mem);
761 
762 	return 0;
763 }
764 
765 static void spi_mem_shutdown(struct spi_device *spi)
766 {
767 	struct spi_mem_driver *memdrv = to_spi_mem_drv(spi->dev.driver);
768 	struct spi_mem *mem = spi_get_drvdata(spi);
769 
770 	if (memdrv->shutdown)
771 		memdrv->shutdown(mem);
772 }
773 
774 /**
775  * spi_mem_driver_register_with_owner() - Register a SPI memory driver
776  * @memdrv: the SPI memory driver to register
777  * @owner: the owner of this driver
778  *
779  * Registers a SPI memory driver.
780  *
781  * Return: 0 in case of success, a negative error core otherwise.
782  */
783 
784 int spi_mem_driver_register_with_owner(struct spi_mem_driver *memdrv,
785 				       struct module *owner)
786 {
787 	memdrv->spidrv.probe = spi_mem_probe;
788 	memdrv->spidrv.remove = spi_mem_remove;
789 	memdrv->spidrv.shutdown = spi_mem_shutdown;
790 
791 	return __spi_register_driver(owner, &memdrv->spidrv);
792 }
793 EXPORT_SYMBOL_GPL(spi_mem_driver_register_with_owner);
794 
795 /**
796  * spi_mem_driver_unregister_with_owner() - Unregister a SPI memory driver
797  * @memdrv: the SPI memory driver to unregister
798  *
799  * Unregisters a SPI memory driver.
800  */
801 void spi_mem_driver_unregister(struct spi_mem_driver *memdrv)
802 {
803 	spi_unregister_driver(&memdrv->spidrv);
804 }
805 EXPORT_SYMBOL_GPL(spi_mem_driver_unregister);
806