xref: /openbmc/linux/drivers/spi/spi.c (revision d7a3d85e)
1 /*
2  * SPI init/core code
3  *
4  * Copyright (C) 2005 David Brownell
5  * Copyright (C) 2008 Secret Lab Technologies Ltd.
6  *
7  * This program is free software; you can redistribute it and/or modify
8  * it under the terms of the GNU General Public License as published by
9  * the Free Software Foundation; either version 2 of the License, or
10  * (at your option) any later version.
11  *
12  * This program is distributed in the hope that it will be useful,
13  * but WITHOUT ANY WARRANTY; without even the implied warranty of
14  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
15  * GNU General Public License for more details.
16  */
17 
18 #include <linux/kernel.h>
19 #include <linux/device.h>
20 #include <linux/init.h>
21 #include <linux/cache.h>
22 #include <linux/dma-mapping.h>
23 #include <linux/dmaengine.h>
24 #include <linux/mutex.h>
25 #include <linux/of_device.h>
26 #include <linux/of_irq.h>
27 #include <linux/clk/clk-conf.h>
28 #include <linux/slab.h>
29 #include <linux/mod_devicetable.h>
30 #include <linux/spi/spi.h>
31 #include <linux/of_gpio.h>
32 #include <linux/pm_runtime.h>
33 #include <linux/pm_domain.h>
34 #include <linux/export.h>
35 #include <linux/sched/rt.h>
36 #include <linux/delay.h>
37 #include <linux/kthread.h>
38 #include <linux/ioport.h>
39 #include <linux/acpi.h>
40 
41 #define CREATE_TRACE_POINTS
42 #include <trace/events/spi.h>
43 
44 static void spidev_release(struct device *dev)
45 {
46 	struct spi_device	*spi = to_spi_device(dev);
47 
48 	/* spi masters may cleanup for released devices */
49 	if (spi->master->cleanup)
50 		spi->master->cleanup(spi);
51 
52 	spi_master_put(spi->master);
53 	kfree(spi);
54 }
55 
56 static ssize_t
57 modalias_show(struct device *dev, struct device_attribute *a, char *buf)
58 {
59 	const struct spi_device	*spi = to_spi_device(dev);
60 	int len;
61 
62 	len = acpi_device_modalias(dev, buf, PAGE_SIZE - 1);
63 	if (len != -ENODEV)
64 		return len;
65 
66 	return sprintf(buf, "%s%s\n", SPI_MODULE_PREFIX, spi->modalias);
67 }
68 static DEVICE_ATTR_RO(modalias);
69 
70 static struct attribute *spi_dev_attrs[] = {
71 	&dev_attr_modalias.attr,
72 	NULL,
73 };
74 ATTRIBUTE_GROUPS(spi_dev);
75 
76 /* modalias support makes "modprobe $MODALIAS" new-style hotplug work,
77  * and the sysfs version makes coldplug work too.
78  */
79 
80 static const struct spi_device_id *spi_match_id(const struct spi_device_id *id,
81 						const struct spi_device *sdev)
82 {
83 	while (id->name[0]) {
84 		if (!strcmp(sdev->modalias, id->name))
85 			return id;
86 		id++;
87 	}
88 	return NULL;
89 }
90 
91 const struct spi_device_id *spi_get_device_id(const struct spi_device *sdev)
92 {
93 	const struct spi_driver *sdrv = to_spi_driver(sdev->dev.driver);
94 
95 	return spi_match_id(sdrv->id_table, sdev);
96 }
97 EXPORT_SYMBOL_GPL(spi_get_device_id);
98 
99 static int spi_match_device(struct device *dev, struct device_driver *drv)
100 {
101 	const struct spi_device	*spi = to_spi_device(dev);
102 	const struct spi_driver	*sdrv = to_spi_driver(drv);
103 
104 	/* Attempt an OF style match */
105 	if (of_driver_match_device(dev, drv))
106 		return 1;
107 
108 	/* Then try ACPI */
109 	if (acpi_driver_match_device(dev, drv))
110 		return 1;
111 
112 	if (sdrv->id_table)
113 		return !!spi_match_id(sdrv->id_table, spi);
114 
115 	return strcmp(spi->modalias, drv->name) == 0;
116 }
117 
118 static int spi_uevent(struct device *dev, struct kobj_uevent_env *env)
119 {
120 	const struct spi_device		*spi = to_spi_device(dev);
121 	int rc;
122 
123 	rc = acpi_device_uevent_modalias(dev, env);
124 	if (rc != -ENODEV)
125 		return rc;
126 
127 	add_uevent_var(env, "MODALIAS=%s%s", SPI_MODULE_PREFIX, spi->modalias);
128 	return 0;
129 }
130 
131 struct bus_type spi_bus_type = {
132 	.name		= "spi",
133 	.dev_groups	= spi_dev_groups,
134 	.match		= spi_match_device,
135 	.uevent		= spi_uevent,
136 };
137 EXPORT_SYMBOL_GPL(spi_bus_type);
138 
139 
140 static int spi_drv_probe(struct device *dev)
141 {
142 	const struct spi_driver		*sdrv = to_spi_driver(dev->driver);
143 	int ret;
144 
145 	ret = of_clk_set_defaults(dev->of_node, false);
146 	if (ret)
147 		return ret;
148 
149 	ret = dev_pm_domain_attach(dev, true);
150 	if (ret != -EPROBE_DEFER) {
151 		ret = sdrv->probe(to_spi_device(dev));
152 		if (ret)
153 			dev_pm_domain_detach(dev, true);
154 	}
155 
156 	return ret;
157 }
158 
159 static int spi_drv_remove(struct device *dev)
160 {
161 	const struct spi_driver		*sdrv = to_spi_driver(dev->driver);
162 	int ret;
163 
164 	ret = sdrv->remove(to_spi_device(dev));
165 	dev_pm_domain_detach(dev, true);
166 
167 	return ret;
168 }
169 
170 static void spi_drv_shutdown(struct device *dev)
171 {
172 	const struct spi_driver		*sdrv = to_spi_driver(dev->driver);
173 
174 	sdrv->shutdown(to_spi_device(dev));
175 }
176 
177 /**
178  * spi_register_driver - register a SPI driver
179  * @sdrv: the driver to register
180  * Context: can sleep
181  */
182 int spi_register_driver(struct spi_driver *sdrv)
183 {
184 	sdrv->driver.bus = &spi_bus_type;
185 	if (sdrv->probe)
186 		sdrv->driver.probe = spi_drv_probe;
187 	if (sdrv->remove)
188 		sdrv->driver.remove = spi_drv_remove;
189 	if (sdrv->shutdown)
190 		sdrv->driver.shutdown = spi_drv_shutdown;
191 	return driver_register(&sdrv->driver);
192 }
193 EXPORT_SYMBOL_GPL(spi_register_driver);
194 
195 /*-------------------------------------------------------------------------*/
196 
197 /* SPI devices should normally not be created by SPI device drivers; that
198  * would make them board-specific.  Similarly with SPI master drivers.
199  * Device registration normally goes into like arch/.../mach.../board-YYY.c
200  * with other readonly (flashable) information about mainboard devices.
201  */
202 
203 struct boardinfo {
204 	struct list_head	list;
205 	struct spi_board_info	board_info;
206 };
207 
208 static LIST_HEAD(board_list);
209 static LIST_HEAD(spi_master_list);
210 
211 /*
212  * Used to protect add/del opertion for board_info list and
213  * spi_master list, and their matching process
214  */
215 static DEFINE_MUTEX(board_lock);
216 
217 /**
218  * spi_alloc_device - Allocate a new SPI device
219  * @master: Controller to which device is connected
220  * Context: can sleep
221  *
222  * Allows a driver to allocate and initialize a spi_device without
223  * registering it immediately.  This allows a driver to directly
224  * fill the spi_device with device parameters before calling
225  * spi_add_device() on it.
226  *
227  * Caller is responsible to call spi_add_device() on the returned
228  * spi_device structure to add it to the SPI master.  If the caller
229  * needs to discard the spi_device without adding it, then it should
230  * call spi_dev_put() on it.
231  *
232  * Returns a pointer to the new device, or NULL.
233  */
234 struct spi_device *spi_alloc_device(struct spi_master *master)
235 {
236 	struct spi_device	*spi;
237 
238 	if (!spi_master_get(master))
239 		return NULL;
240 
241 	spi = kzalloc(sizeof(*spi), GFP_KERNEL);
242 	if (!spi) {
243 		spi_master_put(master);
244 		return NULL;
245 	}
246 
247 	spi->master = master;
248 	spi->dev.parent = &master->dev;
249 	spi->dev.bus = &spi_bus_type;
250 	spi->dev.release = spidev_release;
251 	spi->cs_gpio = -ENOENT;
252 	device_initialize(&spi->dev);
253 	return spi;
254 }
255 EXPORT_SYMBOL_GPL(spi_alloc_device);
256 
257 static void spi_dev_set_name(struct spi_device *spi)
258 {
259 	struct acpi_device *adev = ACPI_COMPANION(&spi->dev);
260 
261 	if (adev) {
262 		dev_set_name(&spi->dev, "spi-%s", acpi_dev_name(adev));
263 		return;
264 	}
265 
266 	dev_set_name(&spi->dev, "%s.%u", dev_name(&spi->master->dev),
267 		     spi->chip_select);
268 }
269 
270 static int spi_dev_check(struct device *dev, void *data)
271 {
272 	struct spi_device *spi = to_spi_device(dev);
273 	struct spi_device *new_spi = data;
274 
275 	if (spi->master == new_spi->master &&
276 	    spi->chip_select == new_spi->chip_select)
277 		return -EBUSY;
278 	return 0;
279 }
280 
281 /**
282  * spi_add_device - Add spi_device allocated with spi_alloc_device
283  * @spi: spi_device to register
284  *
285  * Companion function to spi_alloc_device.  Devices allocated with
286  * spi_alloc_device can be added onto the spi bus with this function.
287  *
288  * Returns 0 on success; negative errno on failure
289  */
290 int spi_add_device(struct spi_device *spi)
291 {
292 	static DEFINE_MUTEX(spi_add_lock);
293 	struct spi_master *master = spi->master;
294 	struct device *dev = master->dev.parent;
295 	int status;
296 
297 	/* Chipselects are numbered 0..max; validate. */
298 	if (spi->chip_select >= master->num_chipselect) {
299 		dev_err(dev, "cs%d >= max %d\n",
300 			spi->chip_select,
301 			master->num_chipselect);
302 		return -EINVAL;
303 	}
304 
305 	/* Set the bus ID string */
306 	spi_dev_set_name(spi);
307 
308 	/* We need to make sure there's no other device with this
309 	 * chipselect **BEFORE** we call setup(), else we'll trash
310 	 * its configuration.  Lock against concurrent add() calls.
311 	 */
312 	mutex_lock(&spi_add_lock);
313 
314 	status = bus_for_each_dev(&spi_bus_type, NULL, spi, spi_dev_check);
315 	if (status) {
316 		dev_err(dev, "chipselect %d already in use\n",
317 				spi->chip_select);
318 		goto done;
319 	}
320 
321 	if (master->cs_gpios)
322 		spi->cs_gpio = master->cs_gpios[spi->chip_select];
323 
324 	/* Drivers may modify this initial i/o setup, but will
325 	 * normally rely on the device being setup.  Devices
326 	 * using SPI_CS_HIGH can't coexist well otherwise...
327 	 */
328 	status = spi_setup(spi);
329 	if (status < 0) {
330 		dev_err(dev, "can't setup %s, status %d\n",
331 				dev_name(&spi->dev), status);
332 		goto done;
333 	}
334 
335 	/* Device may be bound to an active driver when this returns */
336 	status = device_add(&spi->dev);
337 	if (status < 0)
338 		dev_err(dev, "can't add %s, status %d\n",
339 				dev_name(&spi->dev), status);
340 	else
341 		dev_dbg(dev, "registered child %s\n", dev_name(&spi->dev));
342 
343 done:
344 	mutex_unlock(&spi_add_lock);
345 	return status;
346 }
347 EXPORT_SYMBOL_GPL(spi_add_device);
348 
349 /**
350  * spi_new_device - instantiate one new SPI device
351  * @master: Controller to which device is connected
352  * @chip: Describes the SPI device
353  * Context: can sleep
354  *
355  * On typical mainboards, this is purely internal; and it's not needed
356  * after board init creates the hard-wired devices.  Some development
357  * platforms may not be able to use spi_register_board_info though, and
358  * this is exported so that for example a USB or parport based adapter
359  * driver could add devices (which it would learn about out-of-band).
360  *
361  * Returns the new device, or NULL.
362  */
363 struct spi_device *spi_new_device(struct spi_master *master,
364 				  struct spi_board_info *chip)
365 {
366 	struct spi_device	*proxy;
367 	int			status;
368 
369 	/* NOTE:  caller did any chip->bus_num checks necessary.
370 	 *
371 	 * Also, unless we change the return value convention to use
372 	 * error-or-pointer (not NULL-or-pointer), troubleshootability
373 	 * suggests syslogged diagnostics are best here (ugh).
374 	 */
375 
376 	proxy = spi_alloc_device(master);
377 	if (!proxy)
378 		return NULL;
379 
380 	WARN_ON(strlen(chip->modalias) >= sizeof(proxy->modalias));
381 
382 	proxy->chip_select = chip->chip_select;
383 	proxy->max_speed_hz = chip->max_speed_hz;
384 	proxy->mode = chip->mode;
385 	proxy->irq = chip->irq;
386 	strlcpy(proxy->modalias, chip->modalias, sizeof(proxy->modalias));
387 	proxy->dev.platform_data = (void *) chip->platform_data;
388 	proxy->controller_data = chip->controller_data;
389 	proxy->controller_state = NULL;
390 
391 	status = spi_add_device(proxy);
392 	if (status < 0) {
393 		spi_dev_put(proxy);
394 		return NULL;
395 	}
396 
397 	return proxy;
398 }
399 EXPORT_SYMBOL_GPL(spi_new_device);
400 
401 static void spi_match_master_to_boardinfo(struct spi_master *master,
402 				struct spi_board_info *bi)
403 {
404 	struct spi_device *dev;
405 
406 	if (master->bus_num != bi->bus_num)
407 		return;
408 
409 	dev = spi_new_device(master, bi);
410 	if (!dev)
411 		dev_err(master->dev.parent, "can't create new device for %s\n",
412 			bi->modalias);
413 }
414 
415 /**
416  * spi_register_board_info - register SPI devices for a given board
417  * @info: array of chip descriptors
418  * @n: how many descriptors are provided
419  * Context: can sleep
420  *
421  * Board-specific early init code calls this (probably during arch_initcall)
422  * with segments of the SPI device table.  Any device nodes are created later,
423  * after the relevant parent SPI controller (bus_num) is defined.  We keep
424  * this table of devices forever, so that reloading a controller driver will
425  * not make Linux forget about these hard-wired devices.
426  *
427  * Other code can also call this, e.g. a particular add-on board might provide
428  * SPI devices through its expansion connector, so code initializing that board
429  * would naturally declare its SPI devices.
430  *
431  * The board info passed can safely be __initdata ... but be careful of
432  * any embedded pointers (platform_data, etc), they're copied as-is.
433  */
434 int spi_register_board_info(struct spi_board_info const *info, unsigned n)
435 {
436 	struct boardinfo *bi;
437 	int i;
438 
439 	if (!n)
440 		return -EINVAL;
441 
442 	bi = kzalloc(n * sizeof(*bi), GFP_KERNEL);
443 	if (!bi)
444 		return -ENOMEM;
445 
446 	for (i = 0; i < n; i++, bi++, info++) {
447 		struct spi_master *master;
448 
449 		memcpy(&bi->board_info, info, sizeof(*info));
450 		mutex_lock(&board_lock);
451 		list_add_tail(&bi->list, &board_list);
452 		list_for_each_entry(master, &spi_master_list, list)
453 			spi_match_master_to_boardinfo(master, &bi->board_info);
454 		mutex_unlock(&board_lock);
455 	}
456 
457 	return 0;
458 }
459 
460 /*-------------------------------------------------------------------------*/
461 
462 static void spi_set_cs(struct spi_device *spi, bool enable)
463 {
464 	if (spi->mode & SPI_CS_HIGH)
465 		enable = !enable;
466 
467 	if (spi->cs_gpio >= 0)
468 		gpio_set_value(spi->cs_gpio, !enable);
469 	else if (spi->master->set_cs)
470 		spi->master->set_cs(spi, !enable);
471 }
472 
473 #ifdef CONFIG_HAS_DMA
474 static int spi_map_buf(struct spi_master *master, struct device *dev,
475 		       struct sg_table *sgt, void *buf, size_t len,
476 		       enum dma_data_direction dir)
477 {
478 	const bool vmalloced_buf = is_vmalloc_addr(buf);
479 	const int desc_len = vmalloced_buf ? PAGE_SIZE : master->max_dma_len;
480 	const int sgs = DIV_ROUND_UP(len, desc_len);
481 	struct page *vm_page;
482 	void *sg_buf;
483 	size_t min;
484 	int i, ret;
485 
486 	ret = sg_alloc_table(sgt, sgs, GFP_KERNEL);
487 	if (ret != 0)
488 		return ret;
489 
490 	for (i = 0; i < sgs; i++) {
491 		min = min_t(size_t, len, desc_len);
492 
493 		if (vmalloced_buf) {
494 			vm_page = vmalloc_to_page(buf);
495 			if (!vm_page) {
496 				sg_free_table(sgt);
497 				return -ENOMEM;
498 			}
499 			sg_set_page(&sgt->sgl[i], vm_page,
500 				    min, offset_in_page(buf));
501 		} else {
502 			sg_buf = buf;
503 			sg_set_buf(&sgt->sgl[i], sg_buf, min);
504 		}
505 
506 
507 		buf += min;
508 		len -= min;
509 	}
510 
511 	ret = dma_map_sg(dev, sgt->sgl, sgt->nents, dir);
512 	if (!ret)
513 		ret = -ENOMEM;
514 	if (ret < 0) {
515 		sg_free_table(sgt);
516 		return ret;
517 	}
518 
519 	sgt->nents = ret;
520 
521 	return 0;
522 }
523 
524 static void spi_unmap_buf(struct spi_master *master, struct device *dev,
525 			  struct sg_table *sgt, enum dma_data_direction dir)
526 {
527 	if (sgt->orig_nents) {
528 		dma_unmap_sg(dev, sgt->sgl, sgt->orig_nents, dir);
529 		sg_free_table(sgt);
530 	}
531 }
532 
533 static int __spi_map_msg(struct spi_master *master, struct spi_message *msg)
534 {
535 	struct device *tx_dev, *rx_dev;
536 	struct spi_transfer *xfer;
537 	int ret;
538 
539 	if (!master->can_dma)
540 		return 0;
541 
542 	tx_dev = master->dma_tx->device->dev;
543 	rx_dev = master->dma_rx->device->dev;
544 
545 	list_for_each_entry(xfer, &msg->transfers, transfer_list) {
546 		if (!master->can_dma(master, msg->spi, xfer))
547 			continue;
548 
549 		if (xfer->tx_buf != NULL) {
550 			ret = spi_map_buf(master, tx_dev, &xfer->tx_sg,
551 					  (void *)xfer->tx_buf, xfer->len,
552 					  DMA_TO_DEVICE);
553 			if (ret != 0)
554 				return ret;
555 		}
556 
557 		if (xfer->rx_buf != NULL) {
558 			ret = spi_map_buf(master, rx_dev, &xfer->rx_sg,
559 					  xfer->rx_buf, xfer->len,
560 					  DMA_FROM_DEVICE);
561 			if (ret != 0) {
562 				spi_unmap_buf(master, tx_dev, &xfer->tx_sg,
563 					      DMA_TO_DEVICE);
564 				return ret;
565 			}
566 		}
567 	}
568 
569 	master->cur_msg_mapped = true;
570 
571 	return 0;
572 }
573 
574 static int spi_unmap_msg(struct spi_master *master, struct spi_message *msg)
575 {
576 	struct spi_transfer *xfer;
577 	struct device *tx_dev, *rx_dev;
578 
579 	if (!master->cur_msg_mapped || !master->can_dma)
580 		return 0;
581 
582 	tx_dev = master->dma_tx->device->dev;
583 	rx_dev = master->dma_rx->device->dev;
584 
585 	list_for_each_entry(xfer, &msg->transfers, transfer_list) {
586 		/*
587 		 * Restore the original value of tx_buf or rx_buf if they are
588 		 * NULL.
589 		 */
590 		if (xfer->tx_buf == master->dummy_tx)
591 			xfer->tx_buf = NULL;
592 		if (xfer->rx_buf == master->dummy_rx)
593 			xfer->rx_buf = NULL;
594 
595 		if (!master->can_dma(master, msg->spi, xfer))
596 			continue;
597 
598 		spi_unmap_buf(master, rx_dev, &xfer->rx_sg, DMA_FROM_DEVICE);
599 		spi_unmap_buf(master, tx_dev, &xfer->tx_sg, DMA_TO_DEVICE);
600 	}
601 
602 	return 0;
603 }
604 #else /* !CONFIG_HAS_DMA */
605 static inline int __spi_map_msg(struct spi_master *master,
606 				struct spi_message *msg)
607 {
608 	return 0;
609 }
610 
611 static inline int spi_unmap_msg(struct spi_master *master,
612 				struct spi_message *msg)
613 {
614 	return 0;
615 }
616 #endif /* !CONFIG_HAS_DMA */
617 
618 static int spi_map_msg(struct spi_master *master, struct spi_message *msg)
619 {
620 	struct spi_transfer *xfer;
621 	void *tmp;
622 	unsigned int max_tx, max_rx;
623 
624 	if (master->flags & (SPI_MASTER_MUST_RX | SPI_MASTER_MUST_TX)) {
625 		max_tx = 0;
626 		max_rx = 0;
627 
628 		list_for_each_entry(xfer, &msg->transfers, transfer_list) {
629 			if ((master->flags & SPI_MASTER_MUST_TX) &&
630 			    !xfer->tx_buf)
631 				max_tx = max(xfer->len, max_tx);
632 			if ((master->flags & SPI_MASTER_MUST_RX) &&
633 			    !xfer->rx_buf)
634 				max_rx = max(xfer->len, max_rx);
635 		}
636 
637 		if (max_tx) {
638 			tmp = krealloc(master->dummy_tx, max_tx,
639 				       GFP_KERNEL | GFP_DMA);
640 			if (!tmp)
641 				return -ENOMEM;
642 			master->dummy_tx = tmp;
643 			memset(tmp, 0, max_tx);
644 		}
645 
646 		if (max_rx) {
647 			tmp = krealloc(master->dummy_rx, max_rx,
648 				       GFP_KERNEL | GFP_DMA);
649 			if (!tmp)
650 				return -ENOMEM;
651 			master->dummy_rx = tmp;
652 		}
653 
654 		if (max_tx || max_rx) {
655 			list_for_each_entry(xfer, &msg->transfers,
656 					    transfer_list) {
657 				if (!xfer->tx_buf)
658 					xfer->tx_buf = master->dummy_tx;
659 				if (!xfer->rx_buf)
660 					xfer->rx_buf = master->dummy_rx;
661 			}
662 		}
663 	}
664 
665 	return __spi_map_msg(master, msg);
666 }
667 
668 /*
669  * spi_transfer_one_message - Default implementation of transfer_one_message()
670  *
671  * This is a standard implementation of transfer_one_message() for
672  * drivers which impelment a transfer_one() operation.  It provides
673  * standard handling of delays and chip select management.
674  */
675 static int spi_transfer_one_message(struct spi_master *master,
676 				    struct spi_message *msg)
677 {
678 	struct spi_transfer *xfer;
679 	bool keep_cs = false;
680 	int ret = 0;
681 	unsigned long ms = 1;
682 
683 	spi_set_cs(msg->spi, true);
684 
685 	list_for_each_entry(xfer, &msg->transfers, transfer_list) {
686 		trace_spi_transfer_start(msg, xfer);
687 
688 		if (xfer->tx_buf || xfer->rx_buf) {
689 			reinit_completion(&master->xfer_completion);
690 
691 			ret = master->transfer_one(master, msg->spi, xfer);
692 			if (ret < 0) {
693 				dev_err(&msg->spi->dev,
694 					"SPI transfer failed: %d\n", ret);
695 				goto out;
696 			}
697 
698 			if (ret > 0) {
699 				ret = 0;
700 				ms = xfer->len * 8 * 1000 / xfer->speed_hz;
701 				ms += ms + 100; /* some tolerance */
702 
703 				ms = wait_for_completion_timeout(&master->xfer_completion,
704 								 msecs_to_jiffies(ms));
705 			}
706 
707 			if (ms == 0) {
708 				dev_err(&msg->spi->dev,
709 					"SPI transfer timed out\n");
710 				msg->status = -ETIMEDOUT;
711 			}
712 		} else {
713 			if (xfer->len)
714 				dev_err(&msg->spi->dev,
715 					"Bufferless transfer has length %u\n",
716 					xfer->len);
717 		}
718 
719 		trace_spi_transfer_stop(msg, xfer);
720 
721 		if (msg->status != -EINPROGRESS)
722 			goto out;
723 
724 		if (xfer->delay_usecs)
725 			udelay(xfer->delay_usecs);
726 
727 		if (xfer->cs_change) {
728 			if (list_is_last(&xfer->transfer_list,
729 					 &msg->transfers)) {
730 				keep_cs = true;
731 			} else {
732 				spi_set_cs(msg->spi, false);
733 				udelay(10);
734 				spi_set_cs(msg->spi, true);
735 			}
736 		}
737 
738 		msg->actual_length += xfer->len;
739 	}
740 
741 out:
742 	if (ret != 0 || !keep_cs)
743 		spi_set_cs(msg->spi, false);
744 
745 	if (msg->status == -EINPROGRESS)
746 		msg->status = ret;
747 
748 	if (msg->status && master->handle_err)
749 		master->handle_err(master, msg);
750 
751 	spi_finalize_current_message(master);
752 
753 	return ret;
754 }
755 
756 /**
757  * spi_finalize_current_transfer - report completion of a transfer
758  * @master: the master reporting completion
759  *
760  * Called by SPI drivers using the core transfer_one_message()
761  * implementation to notify it that the current interrupt driven
762  * transfer has finished and the next one may be scheduled.
763  */
764 void spi_finalize_current_transfer(struct spi_master *master)
765 {
766 	complete(&master->xfer_completion);
767 }
768 EXPORT_SYMBOL_GPL(spi_finalize_current_transfer);
769 
770 /**
771  * __spi_pump_messages - function which processes spi message queue
772  * @master: master to process queue for
773  * @in_kthread: true if we are in the context of the message pump thread
774  *
775  * This function checks if there is any spi message in the queue that
776  * needs processing and if so call out to the driver to initialize hardware
777  * and transfer each message.
778  *
779  * Note that it is called both from the kthread itself and also from
780  * inside spi_sync(); the queue extraction handling at the top of the
781  * function should deal with this safely.
782  */
783 static void __spi_pump_messages(struct spi_master *master, bool in_kthread)
784 {
785 	unsigned long flags;
786 	bool was_busy = false;
787 	int ret;
788 
789 	/* Lock queue */
790 	spin_lock_irqsave(&master->queue_lock, flags);
791 
792 	/* Make sure we are not already running a message */
793 	if (master->cur_msg) {
794 		spin_unlock_irqrestore(&master->queue_lock, flags);
795 		return;
796 	}
797 
798 	/* If another context is idling the device then defer */
799 	if (master->idling) {
800 		queue_kthread_work(&master->kworker, &master->pump_messages);
801 		spin_unlock_irqrestore(&master->queue_lock, flags);
802 		return;
803 	}
804 
805 	/* Check if the queue is idle */
806 	if (list_empty(&master->queue) || !master->running) {
807 		if (!master->busy) {
808 			spin_unlock_irqrestore(&master->queue_lock, flags);
809 			return;
810 		}
811 
812 		/* Only do teardown in the thread */
813 		if (!in_kthread) {
814 			queue_kthread_work(&master->kworker,
815 					   &master->pump_messages);
816 			spin_unlock_irqrestore(&master->queue_lock, flags);
817 			return;
818 		}
819 
820 		master->busy = false;
821 		master->idling = true;
822 		spin_unlock_irqrestore(&master->queue_lock, flags);
823 
824 		kfree(master->dummy_rx);
825 		master->dummy_rx = NULL;
826 		kfree(master->dummy_tx);
827 		master->dummy_tx = NULL;
828 		if (master->unprepare_transfer_hardware &&
829 		    master->unprepare_transfer_hardware(master))
830 			dev_err(&master->dev,
831 				"failed to unprepare transfer hardware\n");
832 		if (master->auto_runtime_pm) {
833 			pm_runtime_mark_last_busy(master->dev.parent);
834 			pm_runtime_put_autosuspend(master->dev.parent);
835 		}
836 		trace_spi_master_idle(master);
837 
838 		spin_lock_irqsave(&master->queue_lock, flags);
839 		master->idling = false;
840 		spin_unlock_irqrestore(&master->queue_lock, flags);
841 		return;
842 	}
843 
844 	/* Extract head of queue */
845 	master->cur_msg =
846 		list_first_entry(&master->queue, struct spi_message, queue);
847 
848 	list_del_init(&master->cur_msg->queue);
849 	if (master->busy)
850 		was_busy = true;
851 	else
852 		master->busy = true;
853 	spin_unlock_irqrestore(&master->queue_lock, flags);
854 
855 	if (!was_busy && master->auto_runtime_pm) {
856 		ret = pm_runtime_get_sync(master->dev.parent);
857 		if (ret < 0) {
858 			dev_err(&master->dev, "Failed to power device: %d\n",
859 				ret);
860 			return;
861 		}
862 	}
863 
864 	if (!was_busy)
865 		trace_spi_master_busy(master);
866 
867 	if (!was_busy && master->prepare_transfer_hardware) {
868 		ret = master->prepare_transfer_hardware(master);
869 		if (ret) {
870 			dev_err(&master->dev,
871 				"failed to prepare transfer hardware\n");
872 
873 			if (master->auto_runtime_pm)
874 				pm_runtime_put(master->dev.parent);
875 			return;
876 		}
877 	}
878 
879 	trace_spi_message_start(master->cur_msg);
880 
881 	if (master->prepare_message) {
882 		ret = master->prepare_message(master, master->cur_msg);
883 		if (ret) {
884 			dev_err(&master->dev,
885 				"failed to prepare message: %d\n", ret);
886 			master->cur_msg->status = ret;
887 			spi_finalize_current_message(master);
888 			return;
889 		}
890 		master->cur_msg_prepared = true;
891 	}
892 
893 	ret = spi_map_msg(master, master->cur_msg);
894 	if (ret) {
895 		master->cur_msg->status = ret;
896 		spi_finalize_current_message(master);
897 		return;
898 	}
899 
900 	ret = master->transfer_one_message(master, master->cur_msg);
901 	if (ret) {
902 		dev_err(&master->dev,
903 			"failed to transfer one message from queue\n");
904 		return;
905 	}
906 }
907 
908 /**
909  * spi_pump_messages - kthread work function which processes spi message queue
910  * @work: pointer to kthread work struct contained in the master struct
911  */
912 static void spi_pump_messages(struct kthread_work *work)
913 {
914 	struct spi_master *master =
915 		container_of(work, struct spi_master, pump_messages);
916 
917 	__spi_pump_messages(master, true);
918 }
919 
920 static int spi_init_queue(struct spi_master *master)
921 {
922 	struct sched_param param = { .sched_priority = MAX_RT_PRIO - 1 };
923 
924 	master->running = false;
925 	master->busy = false;
926 
927 	init_kthread_worker(&master->kworker);
928 	master->kworker_task = kthread_run(kthread_worker_fn,
929 					   &master->kworker, "%s",
930 					   dev_name(&master->dev));
931 	if (IS_ERR(master->kworker_task)) {
932 		dev_err(&master->dev, "failed to create message pump task\n");
933 		return PTR_ERR(master->kworker_task);
934 	}
935 	init_kthread_work(&master->pump_messages, spi_pump_messages);
936 
937 	/*
938 	 * Master config will indicate if this controller should run the
939 	 * message pump with high (realtime) priority to reduce the transfer
940 	 * latency on the bus by minimising the delay between a transfer
941 	 * request and the scheduling of the message pump thread. Without this
942 	 * setting the message pump thread will remain at default priority.
943 	 */
944 	if (master->rt) {
945 		dev_info(&master->dev,
946 			"will run message pump with realtime priority\n");
947 		sched_setscheduler(master->kworker_task, SCHED_FIFO, &param);
948 	}
949 
950 	return 0;
951 }
952 
953 /**
954  * spi_get_next_queued_message() - called by driver to check for queued
955  * messages
956  * @master: the master to check for queued messages
957  *
958  * If there are more messages in the queue, the next message is returned from
959  * this call.
960  */
961 struct spi_message *spi_get_next_queued_message(struct spi_master *master)
962 {
963 	struct spi_message *next;
964 	unsigned long flags;
965 
966 	/* get a pointer to the next message, if any */
967 	spin_lock_irqsave(&master->queue_lock, flags);
968 	next = list_first_entry_or_null(&master->queue, struct spi_message,
969 					queue);
970 	spin_unlock_irqrestore(&master->queue_lock, flags);
971 
972 	return next;
973 }
974 EXPORT_SYMBOL_GPL(spi_get_next_queued_message);
975 
976 /**
977  * spi_finalize_current_message() - the current message is complete
978  * @master: the master to return the message to
979  *
980  * Called by the driver to notify the core that the message in the front of the
981  * queue is complete and can be removed from the queue.
982  */
983 void spi_finalize_current_message(struct spi_master *master)
984 {
985 	struct spi_message *mesg;
986 	unsigned long flags;
987 	int ret;
988 
989 	spin_lock_irqsave(&master->queue_lock, flags);
990 	mesg = master->cur_msg;
991 	master->cur_msg = NULL;
992 
993 	queue_kthread_work(&master->kworker, &master->pump_messages);
994 	spin_unlock_irqrestore(&master->queue_lock, flags);
995 
996 	spi_unmap_msg(master, mesg);
997 
998 	if (master->cur_msg_prepared && master->unprepare_message) {
999 		ret = master->unprepare_message(master, mesg);
1000 		if (ret) {
1001 			dev_err(&master->dev,
1002 				"failed to unprepare message: %d\n", ret);
1003 		}
1004 	}
1005 
1006 	trace_spi_message_done(mesg);
1007 
1008 	master->cur_msg_prepared = false;
1009 
1010 	mesg->state = NULL;
1011 	if (mesg->complete)
1012 		mesg->complete(mesg->context);
1013 }
1014 EXPORT_SYMBOL_GPL(spi_finalize_current_message);
1015 
1016 static int spi_start_queue(struct spi_master *master)
1017 {
1018 	unsigned long flags;
1019 
1020 	spin_lock_irqsave(&master->queue_lock, flags);
1021 
1022 	if (master->running || master->busy) {
1023 		spin_unlock_irqrestore(&master->queue_lock, flags);
1024 		return -EBUSY;
1025 	}
1026 
1027 	master->running = true;
1028 	master->cur_msg = NULL;
1029 	spin_unlock_irqrestore(&master->queue_lock, flags);
1030 
1031 	queue_kthread_work(&master->kworker, &master->pump_messages);
1032 
1033 	return 0;
1034 }
1035 
1036 static int spi_stop_queue(struct spi_master *master)
1037 {
1038 	unsigned long flags;
1039 	unsigned limit = 500;
1040 	int ret = 0;
1041 
1042 	spin_lock_irqsave(&master->queue_lock, flags);
1043 
1044 	/*
1045 	 * This is a bit lame, but is optimized for the common execution path.
1046 	 * A wait_queue on the master->busy could be used, but then the common
1047 	 * execution path (pump_messages) would be required to call wake_up or
1048 	 * friends on every SPI message. Do this instead.
1049 	 */
1050 	while ((!list_empty(&master->queue) || master->busy) && limit--) {
1051 		spin_unlock_irqrestore(&master->queue_lock, flags);
1052 		usleep_range(10000, 11000);
1053 		spin_lock_irqsave(&master->queue_lock, flags);
1054 	}
1055 
1056 	if (!list_empty(&master->queue) || master->busy)
1057 		ret = -EBUSY;
1058 	else
1059 		master->running = false;
1060 
1061 	spin_unlock_irqrestore(&master->queue_lock, flags);
1062 
1063 	if (ret) {
1064 		dev_warn(&master->dev,
1065 			 "could not stop message queue\n");
1066 		return ret;
1067 	}
1068 	return ret;
1069 }
1070 
1071 static int spi_destroy_queue(struct spi_master *master)
1072 {
1073 	int ret;
1074 
1075 	ret = spi_stop_queue(master);
1076 
1077 	/*
1078 	 * flush_kthread_worker will block until all work is done.
1079 	 * If the reason that stop_queue timed out is that the work will never
1080 	 * finish, then it does no good to call flush/stop thread, so
1081 	 * return anyway.
1082 	 */
1083 	if (ret) {
1084 		dev_err(&master->dev, "problem destroying queue\n");
1085 		return ret;
1086 	}
1087 
1088 	flush_kthread_worker(&master->kworker);
1089 	kthread_stop(master->kworker_task);
1090 
1091 	return 0;
1092 }
1093 
1094 static int __spi_queued_transfer(struct spi_device *spi,
1095 				 struct spi_message *msg,
1096 				 bool need_pump)
1097 {
1098 	struct spi_master *master = spi->master;
1099 	unsigned long flags;
1100 
1101 	spin_lock_irqsave(&master->queue_lock, flags);
1102 
1103 	if (!master->running) {
1104 		spin_unlock_irqrestore(&master->queue_lock, flags);
1105 		return -ESHUTDOWN;
1106 	}
1107 	msg->actual_length = 0;
1108 	msg->status = -EINPROGRESS;
1109 
1110 	list_add_tail(&msg->queue, &master->queue);
1111 	if (!master->busy && need_pump)
1112 		queue_kthread_work(&master->kworker, &master->pump_messages);
1113 
1114 	spin_unlock_irqrestore(&master->queue_lock, flags);
1115 	return 0;
1116 }
1117 
1118 /**
1119  * spi_queued_transfer - transfer function for queued transfers
1120  * @spi: spi device which is requesting transfer
1121  * @msg: spi message which is to handled is queued to driver queue
1122  */
1123 static int spi_queued_transfer(struct spi_device *spi, struct spi_message *msg)
1124 {
1125 	return __spi_queued_transfer(spi, msg, true);
1126 }
1127 
1128 static int spi_master_initialize_queue(struct spi_master *master)
1129 {
1130 	int ret;
1131 
1132 	master->transfer = spi_queued_transfer;
1133 	if (!master->transfer_one_message)
1134 		master->transfer_one_message = spi_transfer_one_message;
1135 
1136 	/* Initialize and start queue */
1137 	ret = spi_init_queue(master);
1138 	if (ret) {
1139 		dev_err(&master->dev, "problem initializing queue\n");
1140 		goto err_init_queue;
1141 	}
1142 	master->queued = true;
1143 	ret = spi_start_queue(master);
1144 	if (ret) {
1145 		dev_err(&master->dev, "problem starting queue\n");
1146 		goto err_start_queue;
1147 	}
1148 
1149 	return 0;
1150 
1151 err_start_queue:
1152 	spi_destroy_queue(master);
1153 err_init_queue:
1154 	return ret;
1155 }
1156 
1157 /*-------------------------------------------------------------------------*/
1158 
1159 #if defined(CONFIG_OF)
1160 static struct spi_device *
1161 of_register_spi_device(struct spi_master *master, struct device_node *nc)
1162 {
1163 	struct spi_device *spi;
1164 	int rc;
1165 	u32 value;
1166 
1167 	/* Alloc an spi_device */
1168 	spi = spi_alloc_device(master);
1169 	if (!spi) {
1170 		dev_err(&master->dev, "spi_device alloc error for %s\n",
1171 			nc->full_name);
1172 		rc = -ENOMEM;
1173 		goto err_out;
1174 	}
1175 
1176 	/* Select device driver */
1177 	rc = of_modalias_node(nc, spi->modalias,
1178 				sizeof(spi->modalias));
1179 	if (rc < 0) {
1180 		dev_err(&master->dev, "cannot find modalias for %s\n",
1181 			nc->full_name);
1182 		goto err_out;
1183 	}
1184 
1185 	/* Device address */
1186 	rc = of_property_read_u32(nc, "reg", &value);
1187 	if (rc) {
1188 		dev_err(&master->dev, "%s has no valid 'reg' property (%d)\n",
1189 			nc->full_name, rc);
1190 		goto err_out;
1191 	}
1192 	spi->chip_select = value;
1193 
1194 	/* Mode (clock phase/polarity/etc.) */
1195 	if (of_find_property(nc, "spi-cpha", NULL))
1196 		spi->mode |= SPI_CPHA;
1197 	if (of_find_property(nc, "spi-cpol", NULL))
1198 		spi->mode |= SPI_CPOL;
1199 	if (of_find_property(nc, "spi-cs-high", NULL))
1200 		spi->mode |= SPI_CS_HIGH;
1201 	if (of_find_property(nc, "spi-3wire", NULL))
1202 		spi->mode |= SPI_3WIRE;
1203 	if (of_find_property(nc, "spi-lsb-first", NULL))
1204 		spi->mode |= SPI_LSB_FIRST;
1205 
1206 	/* Device DUAL/QUAD mode */
1207 	if (!of_property_read_u32(nc, "spi-tx-bus-width", &value)) {
1208 		switch (value) {
1209 		case 1:
1210 			break;
1211 		case 2:
1212 			spi->mode |= SPI_TX_DUAL;
1213 			break;
1214 		case 4:
1215 			spi->mode |= SPI_TX_QUAD;
1216 			break;
1217 		default:
1218 			dev_warn(&master->dev,
1219 				"spi-tx-bus-width %d not supported\n",
1220 				value);
1221 			break;
1222 		}
1223 	}
1224 
1225 	if (!of_property_read_u32(nc, "spi-rx-bus-width", &value)) {
1226 		switch (value) {
1227 		case 1:
1228 			break;
1229 		case 2:
1230 			spi->mode |= SPI_RX_DUAL;
1231 			break;
1232 		case 4:
1233 			spi->mode |= SPI_RX_QUAD;
1234 			break;
1235 		default:
1236 			dev_warn(&master->dev,
1237 				"spi-rx-bus-width %d not supported\n",
1238 				value);
1239 			break;
1240 		}
1241 	}
1242 
1243 	/* Device speed */
1244 	rc = of_property_read_u32(nc, "spi-max-frequency", &value);
1245 	if (rc) {
1246 		dev_err(&master->dev, "%s has no valid 'spi-max-frequency' property (%d)\n",
1247 			nc->full_name, rc);
1248 		goto err_out;
1249 	}
1250 	spi->max_speed_hz = value;
1251 
1252 	/* IRQ */
1253 	spi->irq = irq_of_parse_and_map(nc, 0);
1254 
1255 	/* Store a pointer to the node in the device structure */
1256 	of_node_get(nc);
1257 	spi->dev.of_node = nc;
1258 
1259 	/* Register the new device */
1260 	rc = spi_add_device(spi);
1261 	if (rc) {
1262 		dev_err(&master->dev, "spi_device register error %s\n",
1263 			nc->full_name);
1264 		goto err_out;
1265 	}
1266 
1267 	return spi;
1268 
1269 err_out:
1270 	spi_dev_put(spi);
1271 	return ERR_PTR(rc);
1272 }
1273 
1274 /**
1275  * of_register_spi_devices() - Register child devices onto the SPI bus
1276  * @master:	Pointer to spi_master device
1277  *
1278  * Registers an spi_device for each child node of master node which has a 'reg'
1279  * property.
1280  */
1281 static void of_register_spi_devices(struct spi_master *master)
1282 {
1283 	struct spi_device *spi;
1284 	struct device_node *nc;
1285 
1286 	if (!master->dev.of_node)
1287 		return;
1288 
1289 	for_each_available_child_of_node(master->dev.of_node, nc) {
1290 		spi = of_register_spi_device(master, nc);
1291 		if (IS_ERR(spi))
1292 			dev_warn(&master->dev, "Failed to create SPI device for %s\n",
1293 				nc->full_name);
1294 	}
1295 }
1296 #else
1297 static void of_register_spi_devices(struct spi_master *master) { }
1298 #endif
1299 
1300 #ifdef CONFIG_ACPI
1301 static int acpi_spi_add_resource(struct acpi_resource *ares, void *data)
1302 {
1303 	struct spi_device *spi = data;
1304 
1305 	if (ares->type == ACPI_RESOURCE_TYPE_SERIAL_BUS) {
1306 		struct acpi_resource_spi_serialbus *sb;
1307 
1308 		sb = &ares->data.spi_serial_bus;
1309 		if (sb->type == ACPI_RESOURCE_SERIAL_TYPE_SPI) {
1310 			spi->chip_select = sb->device_selection;
1311 			spi->max_speed_hz = sb->connection_speed;
1312 
1313 			if (sb->clock_phase == ACPI_SPI_SECOND_PHASE)
1314 				spi->mode |= SPI_CPHA;
1315 			if (sb->clock_polarity == ACPI_SPI_START_HIGH)
1316 				spi->mode |= SPI_CPOL;
1317 			if (sb->device_polarity == ACPI_SPI_ACTIVE_HIGH)
1318 				spi->mode |= SPI_CS_HIGH;
1319 		}
1320 	} else if (spi->irq < 0) {
1321 		struct resource r;
1322 
1323 		if (acpi_dev_resource_interrupt(ares, 0, &r))
1324 			spi->irq = r.start;
1325 	}
1326 
1327 	/* Always tell the ACPI core to skip this resource */
1328 	return 1;
1329 }
1330 
1331 static acpi_status acpi_spi_add_device(acpi_handle handle, u32 level,
1332 				       void *data, void **return_value)
1333 {
1334 	struct spi_master *master = data;
1335 	struct list_head resource_list;
1336 	struct acpi_device *adev;
1337 	struct spi_device *spi;
1338 	int ret;
1339 
1340 	if (acpi_bus_get_device(handle, &adev))
1341 		return AE_OK;
1342 	if (acpi_bus_get_status(adev) || !adev->status.present)
1343 		return AE_OK;
1344 
1345 	spi = spi_alloc_device(master);
1346 	if (!spi) {
1347 		dev_err(&master->dev, "failed to allocate SPI device for %s\n",
1348 			dev_name(&adev->dev));
1349 		return AE_NO_MEMORY;
1350 	}
1351 
1352 	ACPI_COMPANION_SET(&spi->dev, adev);
1353 	spi->irq = -1;
1354 
1355 	INIT_LIST_HEAD(&resource_list);
1356 	ret = acpi_dev_get_resources(adev, &resource_list,
1357 				     acpi_spi_add_resource, spi);
1358 	acpi_dev_free_resource_list(&resource_list);
1359 
1360 	if (ret < 0 || !spi->max_speed_hz) {
1361 		spi_dev_put(spi);
1362 		return AE_OK;
1363 	}
1364 
1365 	adev->power.flags.ignore_parent = true;
1366 	strlcpy(spi->modalias, acpi_device_hid(adev), sizeof(spi->modalias));
1367 	if (spi_add_device(spi)) {
1368 		adev->power.flags.ignore_parent = false;
1369 		dev_err(&master->dev, "failed to add SPI device %s from ACPI\n",
1370 			dev_name(&adev->dev));
1371 		spi_dev_put(spi);
1372 	}
1373 
1374 	return AE_OK;
1375 }
1376 
1377 static void acpi_register_spi_devices(struct spi_master *master)
1378 {
1379 	acpi_status status;
1380 	acpi_handle handle;
1381 
1382 	handle = ACPI_HANDLE(master->dev.parent);
1383 	if (!handle)
1384 		return;
1385 
1386 	status = acpi_walk_namespace(ACPI_TYPE_DEVICE, handle, 1,
1387 				     acpi_spi_add_device, NULL,
1388 				     master, NULL);
1389 	if (ACPI_FAILURE(status))
1390 		dev_warn(&master->dev, "failed to enumerate SPI slaves\n");
1391 }
1392 #else
1393 static inline void acpi_register_spi_devices(struct spi_master *master) {}
1394 #endif /* CONFIG_ACPI */
1395 
1396 static void spi_master_release(struct device *dev)
1397 {
1398 	struct spi_master *master;
1399 
1400 	master = container_of(dev, struct spi_master, dev);
1401 	kfree(master);
1402 }
1403 
1404 static struct class spi_master_class = {
1405 	.name		= "spi_master",
1406 	.owner		= THIS_MODULE,
1407 	.dev_release	= spi_master_release,
1408 };
1409 
1410 
1411 
1412 /**
1413  * spi_alloc_master - allocate SPI master controller
1414  * @dev: the controller, possibly using the platform_bus
1415  * @size: how much zeroed driver-private data to allocate; the pointer to this
1416  *	memory is in the driver_data field of the returned device,
1417  *	accessible with spi_master_get_devdata().
1418  * Context: can sleep
1419  *
1420  * This call is used only by SPI master controller drivers, which are the
1421  * only ones directly touching chip registers.  It's how they allocate
1422  * an spi_master structure, prior to calling spi_register_master().
1423  *
1424  * This must be called from context that can sleep.  It returns the SPI
1425  * master structure on success, else NULL.
1426  *
1427  * The caller is responsible for assigning the bus number and initializing
1428  * the master's methods before calling spi_register_master(); and (after errors
1429  * adding the device) calling spi_master_put() and kfree() to prevent a memory
1430  * leak.
1431  */
1432 struct spi_master *spi_alloc_master(struct device *dev, unsigned size)
1433 {
1434 	struct spi_master	*master;
1435 
1436 	if (!dev)
1437 		return NULL;
1438 
1439 	master = kzalloc(size + sizeof(*master), GFP_KERNEL);
1440 	if (!master)
1441 		return NULL;
1442 
1443 	device_initialize(&master->dev);
1444 	master->bus_num = -1;
1445 	master->num_chipselect = 1;
1446 	master->dev.class = &spi_master_class;
1447 	master->dev.parent = get_device(dev);
1448 	spi_master_set_devdata(master, &master[1]);
1449 
1450 	return master;
1451 }
1452 EXPORT_SYMBOL_GPL(spi_alloc_master);
1453 
1454 #ifdef CONFIG_OF
1455 static int of_spi_register_master(struct spi_master *master)
1456 {
1457 	int nb, i, *cs;
1458 	struct device_node *np = master->dev.of_node;
1459 
1460 	if (!np)
1461 		return 0;
1462 
1463 	nb = of_gpio_named_count(np, "cs-gpios");
1464 	master->num_chipselect = max_t(int, nb, master->num_chipselect);
1465 
1466 	/* Return error only for an incorrectly formed cs-gpios property */
1467 	if (nb == 0 || nb == -ENOENT)
1468 		return 0;
1469 	else if (nb < 0)
1470 		return nb;
1471 
1472 	cs = devm_kzalloc(&master->dev,
1473 			  sizeof(int) * master->num_chipselect,
1474 			  GFP_KERNEL);
1475 	master->cs_gpios = cs;
1476 
1477 	if (!master->cs_gpios)
1478 		return -ENOMEM;
1479 
1480 	for (i = 0; i < master->num_chipselect; i++)
1481 		cs[i] = -ENOENT;
1482 
1483 	for (i = 0; i < nb; i++)
1484 		cs[i] = of_get_named_gpio(np, "cs-gpios", i);
1485 
1486 	return 0;
1487 }
1488 #else
1489 static int of_spi_register_master(struct spi_master *master)
1490 {
1491 	return 0;
1492 }
1493 #endif
1494 
1495 /**
1496  * spi_register_master - register SPI master controller
1497  * @master: initialized master, originally from spi_alloc_master()
1498  * Context: can sleep
1499  *
1500  * SPI master controllers connect to their drivers using some non-SPI bus,
1501  * such as the platform bus.  The final stage of probe() in that code
1502  * includes calling spi_register_master() to hook up to this SPI bus glue.
1503  *
1504  * SPI controllers use board specific (often SOC specific) bus numbers,
1505  * and board-specific addressing for SPI devices combines those numbers
1506  * with chip select numbers.  Since SPI does not directly support dynamic
1507  * device identification, boards need configuration tables telling which
1508  * chip is at which address.
1509  *
1510  * This must be called from context that can sleep.  It returns zero on
1511  * success, else a negative error code (dropping the master's refcount).
1512  * After a successful return, the caller is responsible for calling
1513  * spi_unregister_master().
1514  */
1515 int spi_register_master(struct spi_master *master)
1516 {
1517 	static atomic_t		dyn_bus_id = ATOMIC_INIT((1<<15) - 1);
1518 	struct device		*dev = master->dev.parent;
1519 	struct boardinfo	*bi;
1520 	int			status = -ENODEV;
1521 	int			dynamic = 0;
1522 
1523 	if (!dev)
1524 		return -ENODEV;
1525 
1526 	status = of_spi_register_master(master);
1527 	if (status)
1528 		return status;
1529 
1530 	/* even if it's just one always-selected device, there must
1531 	 * be at least one chipselect
1532 	 */
1533 	if (master->num_chipselect == 0)
1534 		return -EINVAL;
1535 
1536 	if ((master->bus_num < 0) && master->dev.of_node)
1537 		master->bus_num = of_alias_get_id(master->dev.of_node, "spi");
1538 
1539 	/* convention:  dynamically assigned bus IDs count down from the max */
1540 	if (master->bus_num < 0) {
1541 		/* FIXME switch to an IDR based scheme, something like
1542 		 * I2C now uses, so we can't run out of "dynamic" IDs
1543 		 */
1544 		master->bus_num = atomic_dec_return(&dyn_bus_id);
1545 		dynamic = 1;
1546 	}
1547 
1548 	INIT_LIST_HEAD(&master->queue);
1549 	spin_lock_init(&master->queue_lock);
1550 	spin_lock_init(&master->bus_lock_spinlock);
1551 	mutex_init(&master->bus_lock_mutex);
1552 	master->bus_lock_flag = 0;
1553 	init_completion(&master->xfer_completion);
1554 	if (!master->max_dma_len)
1555 		master->max_dma_len = INT_MAX;
1556 
1557 	/* register the device, then userspace will see it.
1558 	 * registration fails if the bus ID is in use.
1559 	 */
1560 	dev_set_name(&master->dev, "spi%u", master->bus_num);
1561 	status = device_add(&master->dev);
1562 	if (status < 0)
1563 		goto done;
1564 	dev_dbg(dev, "registered master %s%s\n", dev_name(&master->dev),
1565 			dynamic ? " (dynamic)" : "");
1566 
1567 	/* If we're using a queued driver, start the queue */
1568 	if (master->transfer)
1569 		dev_info(dev, "master is unqueued, this is deprecated\n");
1570 	else {
1571 		status = spi_master_initialize_queue(master);
1572 		if (status) {
1573 			device_del(&master->dev);
1574 			goto done;
1575 		}
1576 	}
1577 
1578 	mutex_lock(&board_lock);
1579 	list_add_tail(&master->list, &spi_master_list);
1580 	list_for_each_entry(bi, &board_list, list)
1581 		spi_match_master_to_boardinfo(master, &bi->board_info);
1582 	mutex_unlock(&board_lock);
1583 
1584 	/* Register devices from the device tree and ACPI */
1585 	of_register_spi_devices(master);
1586 	acpi_register_spi_devices(master);
1587 done:
1588 	return status;
1589 }
1590 EXPORT_SYMBOL_GPL(spi_register_master);
1591 
1592 static void devm_spi_unregister(struct device *dev, void *res)
1593 {
1594 	spi_unregister_master(*(struct spi_master **)res);
1595 }
1596 
1597 /**
1598  * dev_spi_register_master - register managed SPI master controller
1599  * @dev:    device managing SPI master
1600  * @master: initialized master, originally from spi_alloc_master()
1601  * Context: can sleep
1602  *
1603  * Register a SPI device as with spi_register_master() which will
1604  * automatically be unregister
1605  */
1606 int devm_spi_register_master(struct device *dev, struct spi_master *master)
1607 {
1608 	struct spi_master **ptr;
1609 	int ret;
1610 
1611 	ptr = devres_alloc(devm_spi_unregister, sizeof(*ptr), GFP_KERNEL);
1612 	if (!ptr)
1613 		return -ENOMEM;
1614 
1615 	ret = spi_register_master(master);
1616 	if (!ret) {
1617 		*ptr = master;
1618 		devres_add(dev, ptr);
1619 	} else {
1620 		devres_free(ptr);
1621 	}
1622 
1623 	return ret;
1624 }
1625 EXPORT_SYMBOL_GPL(devm_spi_register_master);
1626 
1627 static int __unregister(struct device *dev, void *null)
1628 {
1629 	spi_unregister_device(to_spi_device(dev));
1630 	return 0;
1631 }
1632 
1633 /**
1634  * spi_unregister_master - unregister SPI master controller
1635  * @master: the master being unregistered
1636  * Context: can sleep
1637  *
1638  * This call is used only by SPI master controller drivers, which are the
1639  * only ones directly touching chip registers.
1640  *
1641  * This must be called from context that can sleep.
1642  */
1643 void spi_unregister_master(struct spi_master *master)
1644 {
1645 	int dummy;
1646 
1647 	if (master->queued) {
1648 		if (spi_destroy_queue(master))
1649 			dev_err(&master->dev, "queue remove failed\n");
1650 	}
1651 
1652 	mutex_lock(&board_lock);
1653 	list_del(&master->list);
1654 	mutex_unlock(&board_lock);
1655 
1656 	dummy = device_for_each_child(&master->dev, NULL, __unregister);
1657 	device_unregister(&master->dev);
1658 }
1659 EXPORT_SYMBOL_GPL(spi_unregister_master);
1660 
1661 int spi_master_suspend(struct spi_master *master)
1662 {
1663 	int ret;
1664 
1665 	/* Basically no-ops for non-queued masters */
1666 	if (!master->queued)
1667 		return 0;
1668 
1669 	ret = spi_stop_queue(master);
1670 	if (ret)
1671 		dev_err(&master->dev, "queue stop failed\n");
1672 
1673 	return ret;
1674 }
1675 EXPORT_SYMBOL_GPL(spi_master_suspend);
1676 
1677 int spi_master_resume(struct spi_master *master)
1678 {
1679 	int ret;
1680 
1681 	if (!master->queued)
1682 		return 0;
1683 
1684 	ret = spi_start_queue(master);
1685 	if (ret)
1686 		dev_err(&master->dev, "queue restart failed\n");
1687 
1688 	return ret;
1689 }
1690 EXPORT_SYMBOL_GPL(spi_master_resume);
1691 
1692 static int __spi_master_match(struct device *dev, const void *data)
1693 {
1694 	struct spi_master *m;
1695 	const u16 *bus_num = data;
1696 
1697 	m = container_of(dev, struct spi_master, dev);
1698 	return m->bus_num == *bus_num;
1699 }
1700 
1701 /**
1702  * spi_busnum_to_master - look up master associated with bus_num
1703  * @bus_num: the master's bus number
1704  * Context: can sleep
1705  *
1706  * This call may be used with devices that are registered after
1707  * arch init time.  It returns a refcounted pointer to the relevant
1708  * spi_master (which the caller must release), or NULL if there is
1709  * no such master registered.
1710  */
1711 struct spi_master *spi_busnum_to_master(u16 bus_num)
1712 {
1713 	struct device		*dev;
1714 	struct spi_master	*master = NULL;
1715 
1716 	dev = class_find_device(&spi_master_class, NULL, &bus_num,
1717 				__spi_master_match);
1718 	if (dev)
1719 		master = container_of(dev, struct spi_master, dev);
1720 	/* reference got in class_find_device */
1721 	return master;
1722 }
1723 EXPORT_SYMBOL_GPL(spi_busnum_to_master);
1724 
1725 
1726 /*-------------------------------------------------------------------------*/
1727 
1728 /* Core methods for SPI master protocol drivers.  Some of the
1729  * other core methods are currently defined as inline functions.
1730  */
1731 
1732 /**
1733  * spi_setup - setup SPI mode and clock rate
1734  * @spi: the device whose settings are being modified
1735  * Context: can sleep, and no requests are queued to the device
1736  *
1737  * SPI protocol drivers may need to update the transfer mode if the
1738  * device doesn't work with its default.  They may likewise need
1739  * to update clock rates or word sizes from initial values.  This function
1740  * changes those settings, and must be called from a context that can sleep.
1741  * Except for SPI_CS_HIGH, which takes effect immediately, the changes take
1742  * effect the next time the device is selected and data is transferred to
1743  * or from it.  When this function returns, the spi device is deselected.
1744  *
1745  * Note that this call will fail if the protocol driver specifies an option
1746  * that the underlying controller or its driver does not support.  For
1747  * example, not all hardware supports wire transfers using nine bit words,
1748  * LSB-first wire encoding, or active-high chipselects.
1749  */
1750 int spi_setup(struct spi_device *spi)
1751 {
1752 	unsigned	bad_bits, ugly_bits;
1753 	int		status = 0;
1754 
1755 	/* check mode to prevent that DUAL and QUAD set at the same time
1756 	 */
1757 	if (((spi->mode & SPI_TX_DUAL) && (spi->mode & SPI_TX_QUAD)) ||
1758 		((spi->mode & SPI_RX_DUAL) && (spi->mode & SPI_RX_QUAD))) {
1759 		dev_err(&spi->dev,
1760 		"setup: can not select dual and quad at the same time\n");
1761 		return -EINVAL;
1762 	}
1763 	/* if it is SPI_3WIRE mode, DUAL and QUAD should be forbidden
1764 	 */
1765 	if ((spi->mode & SPI_3WIRE) && (spi->mode &
1766 		(SPI_TX_DUAL | SPI_TX_QUAD | SPI_RX_DUAL | SPI_RX_QUAD)))
1767 		return -EINVAL;
1768 	/* help drivers fail *cleanly* when they need options
1769 	 * that aren't supported with their current master
1770 	 */
1771 	bad_bits = spi->mode & ~spi->master->mode_bits;
1772 	ugly_bits = bad_bits &
1773 		    (SPI_TX_DUAL | SPI_TX_QUAD | SPI_RX_DUAL | SPI_RX_QUAD);
1774 	if (ugly_bits) {
1775 		dev_warn(&spi->dev,
1776 			 "setup: ignoring unsupported mode bits %x\n",
1777 			 ugly_bits);
1778 		spi->mode &= ~ugly_bits;
1779 		bad_bits &= ~ugly_bits;
1780 	}
1781 	if (bad_bits) {
1782 		dev_err(&spi->dev, "setup: unsupported mode bits %x\n",
1783 			bad_bits);
1784 		return -EINVAL;
1785 	}
1786 
1787 	if (!spi->bits_per_word)
1788 		spi->bits_per_word = 8;
1789 
1790 	if (!spi->max_speed_hz)
1791 		spi->max_speed_hz = spi->master->max_speed_hz;
1792 
1793 	spi_set_cs(spi, false);
1794 
1795 	if (spi->master->setup)
1796 		status = spi->master->setup(spi);
1797 
1798 	dev_dbg(&spi->dev, "setup mode %d, %s%s%s%s%u bits/w, %u Hz max --> %d\n",
1799 			(int) (spi->mode & (SPI_CPOL | SPI_CPHA)),
1800 			(spi->mode & SPI_CS_HIGH) ? "cs_high, " : "",
1801 			(spi->mode & SPI_LSB_FIRST) ? "lsb, " : "",
1802 			(spi->mode & SPI_3WIRE) ? "3wire, " : "",
1803 			(spi->mode & SPI_LOOP) ? "loopback, " : "",
1804 			spi->bits_per_word, spi->max_speed_hz,
1805 			status);
1806 
1807 	return status;
1808 }
1809 EXPORT_SYMBOL_GPL(spi_setup);
1810 
1811 static int __spi_validate(struct spi_device *spi, struct spi_message *message)
1812 {
1813 	struct spi_master *master = spi->master;
1814 	struct spi_transfer *xfer;
1815 	int w_size;
1816 
1817 	if (list_empty(&message->transfers))
1818 		return -EINVAL;
1819 
1820 	/* Half-duplex links include original MicroWire, and ones with
1821 	 * only one data pin like SPI_3WIRE (switches direction) or where
1822 	 * either MOSI or MISO is missing.  They can also be caused by
1823 	 * software limitations.
1824 	 */
1825 	if ((master->flags & SPI_MASTER_HALF_DUPLEX)
1826 			|| (spi->mode & SPI_3WIRE)) {
1827 		unsigned flags = master->flags;
1828 
1829 		list_for_each_entry(xfer, &message->transfers, transfer_list) {
1830 			if (xfer->rx_buf && xfer->tx_buf)
1831 				return -EINVAL;
1832 			if ((flags & SPI_MASTER_NO_TX) && xfer->tx_buf)
1833 				return -EINVAL;
1834 			if ((flags & SPI_MASTER_NO_RX) && xfer->rx_buf)
1835 				return -EINVAL;
1836 		}
1837 	}
1838 
1839 	/**
1840 	 * Set transfer bits_per_word and max speed as spi device default if
1841 	 * it is not set for this transfer.
1842 	 * Set transfer tx_nbits and rx_nbits as single transfer default
1843 	 * (SPI_NBITS_SINGLE) if it is not set for this transfer.
1844 	 */
1845 	list_for_each_entry(xfer, &message->transfers, transfer_list) {
1846 		message->frame_length += xfer->len;
1847 		if (!xfer->bits_per_word)
1848 			xfer->bits_per_word = spi->bits_per_word;
1849 
1850 		if (!xfer->speed_hz)
1851 			xfer->speed_hz = spi->max_speed_hz;
1852 
1853 		if (master->max_speed_hz &&
1854 		    xfer->speed_hz > master->max_speed_hz)
1855 			xfer->speed_hz = master->max_speed_hz;
1856 
1857 		if (master->bits_per_word_mask) {
1858 			/* Only 32 bits fit in the mask */
1859 			if (xfer->bits_per_word > 32)
1860 				return -EINVAL;
1861 			if (!(master->bits_per_word_mask &
1862 					BIT(xfer->bits_per_word - 1)))
1863 				return -EINVAL;
1864 		}
1865 
1866 		/*
1867 		 * SPI transfer length should be multiple of SPI word size
1868 		 * where SPI word size should be power-of-two multiple
1869 		 */
1870 		if (xfer->bits_per_word <= 8)
1871 			w_size = 1;
1872 		else if (xfer->bits_per_word <= 16)
1873 			w_size = 2;
1874 		else
1875 			w_size = 4;
1876 
1877 		/* No partial transfers accepted */
1878 		if (xfer->len % w_size)
1879 			return -EINVAL;
1880 
1881 		if (xfer->speed_hz && master->min_speed_hz &&
1882 		    xfer->speed_hz < master->min_speed_hz)
1883 			return -EINVAL;
1884 
1885 		if (xfer->tx_buf && !xfer->tx_nbits)
1886 			xfer->tx_nbits = SPI_NBITS_SINGLE;
1887 		if (xfer->rx_buf && !xfer->rx_nbits)
1888 			xfer->rx_nbits = SPI_NBITS_SINGLE;
1889 		/* check transfer tx/rx_nbits:
1890 		 * 1. check the value matches one of single, dual and quad
1891 		 * 2. check tx/rx_nbits match the mode in spi_device
1892 		 */
1893 		if (xfer->tx_buf) {
1894 			if (xfer->tx_nbits != SPI_NBITS_SINGLE &&
1895 				xfer->tx_nbits != SPI_NBITS_DUAL &&
1896 				xfer->tx_nbits != SPI_NBITS_QUAD)
1897 				return -EINVAL;
1898 			if ((xfer->tx_nbits == SPI_NBITS_DUAL) &&
1899 				!(spi->mode & (SPI_TX_DUAL | SPI_TX_QUAD)))
1900 				return -EINVAL;
1901 			if ((xfer->tx_nbits == SPI_NBITS_QUAD) &&
1902 				!(spi->mode & SPI_TX_QUAD))
1903 				return -EINVAL;
1904 		}
1905 		/* check transfer rx_nbits */
1906 		if (xfer->rx_buf) {
1907 			if (xfer->rx_nbits != SPI_NBITS_SINGLE &&
1908 				xfer->rx_nbits != SPI_NBITS_DUAL &&
1909 				xfer->rx_nbits != SPI_NBITS_QUAD)
1910 				return -EINVAL;
1911 			if ((xfer->rx_nbits == SPI_NBITS_DUAL) &&
1912 				!(spi->mode & (SPI_RX_DUAL | SPI_RX_QUAD)))
1913 				return -EINVAL;
1914 			if ((xfer->rx_nbits == SPI_NBITS_QUAD) &&
1915 				!(spi->mode & SPI_RX_QUAD))
1916 				return -EINVAL;
1917 		}
1918 	}
1919 
1920 	message->status = -EINPROGRESS;
1921 
1922 	return 0;
1923 }
1924 
1925 static int __spi_async(struct spi_device *spi, struct spi_message *message)
1926 {
1927 	struct spi_master *master = spi->master;
1928 
1929 	message->spi = spi;
1930 
1931 	trace_spi_message_submit(message);
1932 
1933 	return master->transfer(spi, message);
1934 }
1935 
1936 /**
1937  * spi_async - asynchronous SPI transfer
1938  * @spi: device with which data will be exchanged
1939  * @message: describes the data transfers, including completion callback
1940  * Context: any (irqs may be blocked, etc)
1941  *
1942  * This call may be used in_irq and other contexts which can't sleep,
1943  * as well as from task contexts which can sleep.
1944  *
1945  * The completion callback is invoked in a context which can't sleep.
1946  * Before that invocation, the value of message->status is undefined.
1947  * When the callback is issued, message->status holds either zero (to
1948  * indicate complete success) or a negative error code.  After that
1949  * callback returns, the driver which issued the transfer request may
1950  * deallocate the associated memory; it's no longer in use by any SPI
1951  * core or controller driver code.
1952  *
1953  * Note that although all messages to a spi_device are handled in
1954  * FIFO order, messages may go to different devices in other orders.
1955  * Some device might be higher priority, or have various "hard" access
1956  * time requirements, for example.
1957  *
1958  * On detection of any fault during the transfer, processing of
1959  * the entire message is aborted, and the device is deselected.
1960  * Until returning from the associated message completion callback,
1961  * no other spi_message queued to that device will be processed.
1962  * (This rule applies equally to all the synchronous transfer calls,
1963  * which are wrappers around this core asynchronous primitive.)
1964  */
1965 int spi_async(struct spi_device *spi, struct spi_message *message)
1966 {
1967 	struct spi_master *master = spi->master;
1968 	int ret;
1969 	unsigned long flags;
1970 
1971 	ret = __spi_validate(spi, message);
1972 	if (ret != 0)
1973 		return ret;
1974 
1975 	spin_lock_irqsave(&master->bus_lock_spinlock, flags);
1976 
1977 	if (master->bus_lock_flag)
1978 		ret = -EBUSY;
1979 	else
1980 		ret = __spi_async(spi, message);
1981 
1982 	spin_unlock_irqrestore(&master->bus_lock_spinlock, flags);
1983 
1984 	return ret;
1985 }
1986 EXPORT_SYMBOL_GPL(spi_async);
1987 
1988 /**
1989  * spi_async_locked - version of spi_async with exclusive bus usage
1990  * @spi: device with which data will be exchanged
1991  * @message: describes the data transfers, including completion callback
1992  * Context: any (irqs may be blocked, etc)
1993  *
1994  * This call may be used in_irq and other contexts which can't sleep,
1995  * as well as from task contexts which can sleep.
1996  *
1997  * The completion callback is invoked in a context which can't sleep.
1998  * Before that invocation, the value of message->status is undefined.
1999  * When the callback is issued, message->status holds either zero (to
2000  * indicate complete success) or a negative error code.  After that
2001  * callback returns, the driver which issued the transfer request may
2002  * deallocate the associated memory; it's no longer in use by any SPI
2003  * core or controller driver code.
2004  *
2005  * Note that although all messages to a spi_device are handled in
2006  * FIFO order, messages may go to different devices in other orders.
2007  * Some device might be higher priority, or have various "hard" access
2008  * time requirements, for example.
2009  *
2010  * On detection of any fault during the transfer, processing of
2011  * the entire message is aborted, and the device is deselected.
2012  * Until returning from the associated message completion callback,
2013  * no other spi_message queued to that device will be processed.
2014  * (This rule applies equally to all the synchronous transfer calls,
2015  * which are wrappers around this core asynchronous primitive.)
2016  */
2017 int spi_async_locked(struct spi_device *spi, struct spi_message *message)
2018 {
2019 	struct spi_master *master = spi->master;
2020 	int ret;
2021 	unsigned long flags;
2022 
2023 	ret = __spi_validate(spi, message);
2024 	if (ret != 0)
2025 		return ret;
2026 
2027 	spin_lock_irqsave(&master->bus_lock_spinlock, flags);
2028 
2029 	ret = __spi_async(spi, message);
2030 
2031 	spin_unlock_irqrestore(&master->bus_lock_spinlock, flags);
2032 
2033 	return ret;
2034 
2035 }
2036 EXPORT_SYMBOL_GPL(spi_async_locked);
2037 
2038 
2039 /*-------------------------------------------------------------------------*/
2040 
2041 /* Utility methods for SPI master protocol drivers, layered on
2042  * top of the core.  Some other utility methods are defined as
2043  * inline functions.
2044  */
2045 
2046 static void spi_complete(void *arg)
2047 {
2048 	complete(arg);
2049 }
2050 
2051 static int __spi_sync(struct spi_device *spi, struct spi_message *message,
2052 		      int bus_locked)
2053 {
2054 	DECLARE_COMPLETION_ONSTACK(done);
2055 	int status;
2056 	struct spi_master *master = spi->master;
2057 	unsigned long flags;
2058 
2059 	status = __spi_validate(spi, message);
2060 	if (status != 0)
2061 		return status;
2062 
2063 	message->complete = spi_complete;
2064 	message->context = &done;
2065 	message->spi = spi;
2066 
2067 	if (!bus_locked)
2068 		mutex_lock(&master->bus_lock_mutex);
2069 
2070 	/* If we're not using the legacy transfer method then we will
2071 	 * try to transfer in the calling context so special case.
2072 	 * This code would be less tricky if we could remove the
2073 	 * support for driver implemented message queues.
2074 	 */
2075 	if (master->transfer == spi_queued_transfer) {
2076 		spin_lock_irqsave(&master->bus_lock_spinlock, flags);
2077 
2078 		trace_spi_message_submit(message);
2079 
2080 		status = __spi_queued_transfer(spi, message, false);
2081 
2082 		spin_unlock_irqrestore(&master->bus_lock_spinlock, flags);
2083 	} else {
2084 		status = spi_async_locked(spi, message);
2085 	}
2086 
2087 	if (!bus_locked)
2088 		mutex_unlock(&master->bus_lock_mutex);
2089 
2090 	if (status == 0) {
2091 		/* Push out the messages in the calling context if we
2092 		 * can.
2093 		 */
2094 		if (master->transfer == spi_queued_transfer)
2095 			__spi_pump_messages(master, false);
2096 
2097 		wait_for_completion(&done);
2098 		status = message->status;
2099 	}
2100 	message->context = NULL;
2101 	return status;
2102 }
2103 
2104 /**
2105  * spi_sync - blocking/synchronous SPI data transfers
2106  * @spi: device with which data will be exchanged
2107  * @message: describes the data transfers
2108  * Context: can sleep
2109  *
2110  * This call may only be used from a context that may sleep.  The sleep
2111  * is non-interruptible, and has no timeout.  Low-overhead controller
2112  * drivers may DMA directly into and out of the message buffers.
2113  *
2114  * Note that the SPI device's chip select is active during the message,
2115  * and then is normally disabled between messages.  Drivers for some
2116  * frequently-used devices may want to minimize costs of selecting a chip,
2117  * by leaving it selected in anticipation that the next message will go
2118  * to the same chip.  (That may increase power usage.)
2119  *
2120  * Also, the caller is guaranteeing that the memory associated with the
2121  * message will not be freed before this call returns.
2122  *
2123  * It returns zero on success, else a negative error code.
2124  */
2125 int spi_sync(struct spi_device *spi, struct spi_message *message)
2126 {
2127 	return __spi_sync(spi, message, 0);
2128 }
2129 EXPORT_SYMBOL_GPL(spi_sync);
2130 
2131 /**
2132  * spi_sync_locked - version of spi_sync with exclusive bus usage
2133  * @spi: device with which data will be exchanged
2134  * @message: describes the data transfers
2135  * Context: can sleep
2136  *
2137  * This call may only be used from a context that may sleep.  The sleep
2138  * is non-interruptible, and has no timeout.  Low-overhead controller
2139  * drivers may DMA directly into and out of the message buffers.
2140  *
2141  * This call should be used by drivers that require exclusive access to the
2142  * SPI bus. It has to be preceded by a spi_bus_lock call. The SPI bus must
2143  * be released by a spi_bus_unlock call when the exclusive access is over.
2144  *
2145  * It returns zero on success, else a negative error code.
2146  */
2147 int spi_sync_locked(struct spi_device *spi, struct spi_message *message)
2148 {
2149 	return __spi_sync(spi, message, 1);
2150 }
2151 EXPORT_SYMBOL_GPL(spi_sync_locked);
2152 
2153 /**
2154  * spi_bus_lock - obtain a lock for exclusive SPI bus usage
2155  * @master: SPI bus master that should be locked for exclusive bus access
2156  * Context: can sleep
2157  *
2158  * This call may only be used from a context that may sleep.  The sleep
2159  * is non-interruptible, and has no timeout.
2160  *
2161  * This call should be used by drivers that require exclusive access to the
2162  * SPI bus. The SPI bus must be released by a spi_bus_unlock call when the
2163  * exclusive access is over. Data transfer must be done by spi_sync_locked
2164  * and spi_async_locked calls when the SPI bus lock is held.
2165  *
2166  * It returns zero on success, else a negative error code.
2167  */
2168 int spi_bus_lock(struct spi_master *master)
2169 {
2170 	unsigned long flags;
2171 
2172 	mutex_lock(&master->bus_lock_mutex);
2173 
2174 	spin_lock_irqsave(&master->bus_lock_spinlock, flags);
2175 	master->bus_lock_flag = 1;
2176 	spin_unlock_irqrestore(&master->bus_lock_spinlock, flags);
2177 
2178 	/* mutex remains locked until spi_bus_unlock is called */
2179 
2180 	return 0;
2181 }
2182 EXPORT_SYMBOL_GPL(spi_bus_lock);
2183 
2184 /**
2185  * spi_bus_unlock - release the lock for exclusive SPI bus usage
2186  * @master: SPI bus master that was locked for exclusive bus access
2187  * Context: can sleep
2188  *
2189  * This call may only be used from a context that may sleep.  The sleep
2190  * is non-interruptible, and has no timeout.
2191  *
2192  * This call releases an SPI bus lock previously obtained by an spi_bus_lock
2193  * call.
2194  *
2195  * It returns zero on success, else a negative error code.
2196  */
2197 int spi_bus_unlock(struct spi_master *master)
2198 {
2199 	master->bus_lock_flag = 0;
2200 
2201 	mutex_unlock(&master->bus_lock_mutex);
2202 
2203 	return 0;
2204 }
2205 EXPORT_SYMBOL_GPL(spi_bus_unlock);
2206 
2207 /* portable code must never pass more than 32 bytes */
2208 #define	SPI_BUFSIZ	max(32, SMP_CACHE_BYTES)
2209 
2210 static u8	*buf;
2211 
2212 /**
2213  * spi_write_then_read - SPI synchronous write followed by read
2214  * @spi: device with which data will be exchanged
2215  * @txbuf: data to be written (need not be dma-safe)
2216  * @n_tx: size of txbuf, in bytes
2217  * @rxbuf: buffer into which data will be read (need not be dma-safe)
2218  * @n_rx: size of rxbuf, in bytes
2219  * Context: can sleep
2220  *
2221  * This performs a half duplex MicroWire style transaction with the
2222  * device, sending txbuf and then reading rxbuf.  The return value
2223  * is zero for success, else a negative errno status code.
2224  * This call may only be used from a context that may sleep.
2225  *
2226  * Parameters to this routine are always copied using a small buffer;
2227  * portable code should never use this for more than 32 bytes.
2228  * Performance-sensitive or bulk transfer code should instead use
2229  * spi_{async,sync}() calls with dma-safe buffers.
2230  */
2231 int spi_write_then_read(struct spi_device *spi,
2232 		const void *txbuf, unsigned n_tx,
2233 		void *rxbuf, unsigned n_rx)
2234 {
2235 	static DEFINE_MUTEX(lock);
2236 
2237 	int			status;
2238 	struct spi_message	message;
2239 	struct spi_transfer	x[2];
2240 	u8			*local_buf;
2241 
2242 	/* Use preallocated DMA-safe buffer if we can.  We can't avoid
2243 	 * copying here, (as a pure convenience thing), but we can
2244 	 * keep heap costs out of the hot path unless someone else is
2245 	 * using the pre-allocated buffer or the transfer is too large.
2246 	 */
2247 	if ((n_tx + n_rx) > SPI_BUFSIZ || !mutex_trylock(&lock)) {
2248 		local_buf = kmalloc(max((unsigned)SPI_BUFSIZ, n_tx + n_rx),
2249 				    GFP_KERNEL | GFP_DMA);
2250 		if (!local_buf)
2251 			return -ENOMEM;
2252 	} else {
2253 		local_buf = buf;
2254 	}
2255 
2256 	spi_message_init(&message);
2257 	memset(x, 0, sizeof(x));
2258 	if (n_tx) {
2259 		x[0].len = n_tx;
2260 		spi_message_add_tail(&x[0], &message);
2261 	}
2262 	if (n_rx) {
2263 		x[1].len = n_rx;
2264 		spi_message_add_tail(&x[1], &message);
2265 	}
2266 
2267 	memcpy(local_buf, txbuf, n_tx);
2268 	x[0].tx_buf = local_buf;
2269 	x[1].rx_buf = local_buf + n_tx;
2270 
2271 	/* do the i/o */
2272 	status = spi_sync(spi, &message);
2273 	if (status == 0)
2274 		memcpy(rxbuf, x[1].rx_buf, n_rx);
2275 
2276 	if (x[0].tx_buf == buf)
2277 		mutex_unlock(&lock);
2278 	else
2279 		kfree(local_buf);
2280 
2281 	return status;
2282 }
2283 EXPORT_SYMBOL_GPL(spi_write_then_read);
2284 
2285 /*-------------------------------------------------------------------------*/
2286 
2287 #if IS_ENABLED(CONFIG_OF_DYNAMIC)
2288 static int __spi_of_device_match(struct device *dev, void *data)
2289 {
2290 	return dev->of_node == data;
2291 }
2292 
2293 /* must call put_device() when done with returned spi_device device */
2294 static struct spi_device *of_find_spi_device_by_node(struct device_node *node)
2295 {
2296 	struct device *dev = bus_find_device(&spi_bus_type, NULL, node,
2297 						__spi_of_device_match);
2298 	return dev ? to_spi_device(dev) : NULL;
2299 }
2300 
2301 static int __spi_of_master_match(struct device *dev, const void *data)
2302 {
2303 	return dev->of_node == data;
2304 }
2305 
2306 /* the spi masters are not using spi_bus, so we find it with another way */
2307 static struct spi_master *of_find_spi_master_by_node(struct device_node *node)
2308 {
2309 	struct device *dev;
2310 
2311 	dev = class_find_device(&spi_master_class, NULL, node,
2312 				__spi_of_master_match);
2313 	if (!dev)
2314 		return NULL;
2315 
2316 	/* reference got in class_find_device */
2317 	return container_of(dev, struct spi_master, dev);
2318 }
2319 
2320 static int of_spi_notify(struct notifier_block *nb, unsigned long action,
2321 			 void *arg)
2322 {
2323 	struct of_reconfig_data *rd = arg;
2324 	struct spi_master *master;
2325 	struct spi_device *spi;
2326 
2327 	switch (of_reconfig_get_state_change(action, arg)) {
2328 	case OF_RECONFIG_CHANGE_ADD:
2329 		master = of_find_spi_master_by_node(rd->dn->parent);
2330 		if (master == NULL)
2331 			return NOTIFY_OK;	/* not for us */
2332 
2333 		spi = of_register_spi_device(master, rd->dn);
2334 		put_device(&master->dev);
2335 
2336 		if (IS_ERR(spi)) {
2337 			pr_err("%s: failed to create for '%s'\n",
2338 					__func__, rd->dn->full_name);
2339 			return notifier_from_errno(PTR_ERR(spi));
2340 		}
2341 		break;
2342 
2343 	case OF_RECONFIG_CHANGE_REMOVE:
2344 		/* find our device by node */
2345 		spi = of_find_spi_device_by_node(rd->dn);
2346 		if (spi == NULL)
2347 			return NOTIFY_OK;	/* no? not meant for us */
2348 
2349 		/* unregister takes one ref away */
2350 		spi_unregister_device(spi);
2351 
2352 		/* and put the reference of the find */
2353 		put_device(&spi->dev);
2354 		break;
2355 	}
2356 
2357 	return NOTIFY_OK;
2358 }
2359 
2360 static struct notifier_block spi_of_notifier = {
2361 	.notifier_call = of_spi_notify,
2362 };
2363 #else /* IS_ENABLED(CONFIG_OF_DYNAMIC) */
2364 extern struct notifier_block spi_of_notifier;
2365 #endif /* IS_ENABLED(CONFIG_OF_DYNAMIC) */
2366 
2367 static int __init spi_init(void)
2368 {
2369 	int	status;
2370 
2371 	buf = kmalloc(SPI_BUFSIZ, GFP_KERNEL);
2372 	if (!buf) {
2373 		status = -ENOMEM;
2374 		goto err0;
2375 	}
2376 
2377 	status = bus_register(&spi_bus_type);
2378 	if (status < 0)
2379 		goto err1;
2380 
2381 	status = class_register(&spi_master_class);
2382 	if (status < 0)
2383 		goto err2;
2384 
2385 	if (IS_ENABLED(CONFIG_OF_DYNAMIC))
2386 		WARN_ON(of_reconfig_notifier_register(&spi_of_notifier));
2387 
2388 	return 0;
2389 
2390 err2:
2391 	bus_unregister(&spi_bus_type);
2392 err1:
2393 	kfree(buf);
2394 	buf = NULL;
2395 err0:
2396 	return status;
2397 }
2398 
2399 /* board_info is normally registered in arch_initcall(),
2400  * but even essential drivers wait till later
2401  *
2402  * REVISIT only boardinfo really needs static linking. the rest (device and
2403  * driver registration) _could_ be dynamically linked (modular) ... costs
2404  * include needing to have boardinfo data structures be much more public.
2405  */
2406 postcore_initcall(spi_init);
2407 
2408