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d2876d08 DB |
1 | #include <linux/kernel.h> |
2 | #include <linux/module.h> | |
3 | #include <linux/irq.h> | |
4 | #include <linux/spinlock.h> | |
d8f388d8 DB |
5 | #include <linux/device.h> |
6 | #include <linux/err.h> | |
7 | #include <linux/debugfs.h> | |
8 | #include <linux/seq_file.h> | |
9 | #include <linux/gpio.h> | |
d2876d08 DB |
10 | |
11 | ||
12 | /* Optional implementation infrastructure for GPIO interfaces. | |
13 | * | |
14 | * Platforms may want to use this if they tend to use very many GPIOs | |
15 | * that aren't part of a System-On-Chip core; or across I2C/SPI/etc. | |
16 | * | |
17 | * When kernel footprint or instruction count is an issue, simpler | |
18 | * implementations may be preferred. The GPIO programming interface | |
19 | * allows for inlining speed-critical get/set operations for common | |
20 | * cases, so that access to SOC-integrated GPIOs can sometimes cost | |
21 | * only an instruction or two per bit. | |
22 | */ | |
23 | ||
24 | ||
25 | /* When debugging, extend minimal trust to callers and platform code. | |
26 | * Also emit diagnostic messages that may help initial bringup, when | |
27 | * board setup or driver bugs are most common. | |
28 | * | |
29 | * Otherwise, minimize overhead in what may be bitbanging codepaths. | |
30 | */ | |
31 | #ifdef DEBUG | |
32 | #define extra_checks 1 | |
33 | #else | |
34 | #define extra_checks 0 | |
35 | #endif | |
36 | ||
37 | /* gpio_lock prevents conflicts during gpio_desc[] table updates. | |
38 | * While any GPIO is requested, its gpio_chip is not removable; | |
39 | * each GPIO's "requested" flag serves as a lock and refcount. | |
40 | */ | |
41 | static DEFINE_SPINLOCK(gpio_lock); | |
42 | ||
43 | struct gpio_desc { | |
44 | struct gpio_chip *chip; | |
45 | unsigned long flags; | |
46 | /* flag symbols are bit numbers */ | |
47 | #define FLAG_REQUESTED 0 | |
48 | #define FLAG_IS_OUT 1 | |
169b6a7a | 49 | #define FLAG_RESERVED 2 |
d8f388d8 DB |
50 | #define FLAG_EXPORT 3 /* protected by sysfs_lock */ |
51 | #define FLAG_SYSFS 4 /* exported via /sys/class/gpio/control */ | |
d2876d08 DB |
52 | |
53 | #ifdef CONFIG_DEBUG_FS | |
54 | const char *label; | |
55 | #endif | |
56 | }; | |
57 | static struct gpio_desc gpio_desc[ARCH_NR_GPIOS]; | |
58 | ||
59 | static inline void desc_set_label(struct gpio_desc *d, const char *label) | |
60 | { | |
61 | #ifdef CONFIG_DEBUG_FS | |
62 | d->label = label; | |
63 | #endif | |
64 | } | |
65 | ||
66 | /* Warn when drivers omit gpio_request() calls -- legal but ill-advised | |
67 | * when setting direction, and otherwise illegal. Until board setup code | |
68 | * and drivers use explicit requests everywhere (which won't happen when | |
69 | * those calls have no teeth) we can't avoid autorequesting. This nag | |
70 | * message should motivate switching to explicit requests... | |
71 | */ | |
72 | static void gpio_ensure_requested(struct gpio_desc *desc) | |
73 | { | |
74 | if (test_and_set_bit(FLAG_REQUESTED, &desc->flags) == 0) { | |
75 | pr_warning("GPIO-%d autorequested\n", (int)(desc - gpio_desc)); | |
76 | desc_set_label(desc, "[auto]"); | |
438d8908 GL |
77 | if (!try_module_get(desc->chip->owner)) |
78 | pr_err("GPIO-%d: module can't be gotten \n", | |
79 | (int)(desc - gpio_desc)); | |
d2876d08 DB |
80 | } |
81 | } | |
82 | ||
83 | /* caller holds gpio_lock *OR* gpio is marked as requested */ | |
84 | static inline struct gpio_chip *gpio_to_chip(unsigned gpio) | |
85 | { | |
86 | return gpio_desc[gpio].chip; | |
87 | } | |
88 | ||
8d0aab2f AV |
89 | /* dynamic allocation of GPIOs, e.g. on a hotplugged device */ |
90 | static int gpiochip_find_base(int ngpio) | |
91 | { | |
92 | int i; | |
93 | int spare = 0; | |
94 | int base = -ENOSPC; | |
95 | ||
96 | for (i = ARCH_NR_GPIOS - 1; i >= 0 ; i--) { | |
169b6a7a AV |
97 | struct gpio_desc *desc = &gpio_desc[i]; |
98 | struct gpio_chip *chip = desc->chip; | |
8d0aab2f | 99 | |
169b6a7a | 100 | if (!chip && !test_bit(FLAG_RESERVED, &desc->flags)) { |
8d0aab2f AV |
101 | spare++; |
102 | if (spare == ngpio) { | |
103 | base = i; | |
104 | break; | |
105 | } | |
106 | } else { | |
107 | spare = 0; | |
169b6a7a AV |
108 | if (chip) |
109 | i -= chip->ngpio - 1; | |
8d0aab2f AV |
110 | } |
111 | } | |
112 | ||
113 | if (gpio_is_valid(base)) | |
114 | pr_debug("%s: found new base at %d\n", __func__, base); | |
115 | return base; | |
116 | } | |
117 | ||
169b6a7a AV |
118 | /** |
119 | * gpiochip_reserve() - reserve range of gpios to use with platform code only | |
120 | * @start: starting gpio number | |
121 | * @ngpio: number of gpios to reserve | |
122 | * Context: platform init, potentially before irqs or kmalloc will work | |
123 | * | |
124 | * Returns a negative errno if any gpio within the range is already reserved | |
125 | * or registered, else returns zero as a success code. Use this function | |
126 | * to mark a range of gpios as unavailable for dynamic gpio number allocation, | |
127 | * for example because its driver support is not yet loaded. | |
128 | */ | |
129 | int __init gpiochip_reserve(int start, int ngpio) | |
130 | { | |
131 | int ret = 0; | |
132 | unsigned long flags; | |
133 | int i; | |
134 | ||
bff5fda9 | 135 | if (!gpio_is_valid(start) || !gpio_is_valid(start + ngpio - 1)) |
169b6a7a AV |
136 | return -EINVAL; |
137 | ||
138 | spin_lock_irqsave(&gpio_lock, flags); | |
139 | ||
140 | for (i = start; i < start + ngpio; i++) { | |
141 | struct gpio_desc *desc = &gpio_desc[i]; | |
142 | ||
143 | if (desc->chip || test_bit(FLAG_RESERVED, &desc->flags)) { | |
144 | ret = -EBUSY; | |
145 | goto err; | |
146 | } | |
147 | ||
148 | set_bit(FLAG_RESERVED, &desc->flags); | |
149 | } | |
150 | ||
151 | pr_debug("%s: reserved gpios from %d to %d\n", | |
152 | __func__, start, start + ngpio - 1); | |
153 | err: | |
154 | spin_unlock_irqrestore(&gpio_lock, flags); | |
155 | ||
156 | return ret; | |
157 | } | |
158 | ||
d8f388d8 DB |
159 | #ifdef CONFIG_GPIO_SYSFS |
160 | ||
161 | /* lock protects against unexport_gpio() being called while | |
162 | * sysfs files are active. | |
163 | */ | |
164 | static DEFINE_MUTEX(sysfs_lock); | |
165 | ||
166 | /* | |
167 | * /sys/class/gpio/gpioN... only for GPIOs that are exported | |
168 | * /direction | |
169 | * * MAY BE OMITTED if kernel won't allow direction changes | |
170 | * * is read/write as "in" or "out" | |
171 | * * may also be written as "high" or "low", initializing | |
172 | * output value as specified ("out" implies "low") | |
173 | * /value | |
174 | * * always readable, subject to hardware behavior | |
175 | * * may be writable, as zero/nonzero | |
176 | * | |
177 | * REVISIT there will likely be an attribute for configuring async | |
178 | * notifications, e.g. to specify polling interval or IRQ trigger type | |
179 | * that would for example trigger a poll() on the "value". | |
180 | */ | |
181 | ||
182 | static ssize_t gpio_direction_show(struct device *dev, | |
183 | struct device_attribute *attr, char *buf) | |
184 | { | |
185 | const struct gpio_desc *desc = dev_get_drvdata(dev); | |
186 | ssize_t status; | |
187 | ||
188 | mutex_lock(&sysfs_lock); | |
189 | ||
190 | if (!test_bit(FLAG_EXPORT, &desc->flags)) | |
191 | status = -EIO; | |
192 | else | |
193 | status = sprintf(buf, "%s\n", | |
194 | test_bit(FLAG_IS_OUT, &desc->flags) | |
195 | ? "out" : "in"); | |
196 | ||
197 | mutex_unlock(&sysfs_lock); | |
198 | return status; | |
199 | } | |
200 | ||
201 | static ssize_t gpio_direction_store(struct device *dev, | |
202 | struct device_attribute *attr, const char *buf, size_t size) | |
203 | { | |
204 | const struct gpio_desc *desc = dev_get_drvdata(dev); | |
205 | unsigned gpio = desc - gpio_desc; | |
206 | ssize_t status; | |
207 | ||
208 | mutex_lock(&sysfs_lock); | |
209 | ||
210 | if (!test_bit(FLAG_EXPORT, &desc->flags)) | |
211 | status = -EIO; | |
212 | else if (sysfs_streq(buf, "high")) | |
213 | status = gpio_direction_output(gpio, 1); | |
214 | else if (sysfs_streq(buf, "out") || sysfs_streq(buf, "low")) | |
215 | status = gpio_direction_output(gpio, 0); | |
216 | else if (sysfs_streq(buf, "in")) | |
217 | status = gpio_direction_input(gpio); | |
218 | else | |
219 | status = -EINVAL; | |
220 | ||
221 | mutex_unlock(&sysfs_lock); | |
222 | return status ? : size; | |
223 | } | |
224 | ||
225 | static const DEVICE_ATTR(direction, 0644, | |
226 | gpio_direction_show, gpio_direction_store); | |
227 | ||
228 | static ssize_t gpio_value_show(struct device *dev, | |
229 | struct device_attribute *attr, char *buf) | |
230 | { | |
231 | const struct gpio_desc *desc = dev_get_drvdata(dev); | |
232 | unsigned gpio = desc - gpio_desc; | |
233 | ssize_t status; | |
234 | ||
235 | mutex_lock(&sysfs_lock); | |
236 | ||
237 | if (!test_bit(FLAG_EXPORT, &desc->flags)) | |
238 | status = -EIO; | |
239 | else | |
240 | status = sprintf(buf, "%d\n", gpio_get_value_cansleep(gpio)); | |
241 | ||
242 | mutex_unlock(&sysfs_lock); | |
243 | return status; | |
244 | } | |
245 | ||
246 | static ssize_t gpio_value_store(struct device *dev, | |
247 | struct device_attribute *attr, const char *buf, size_t size) | |
248 | { | |
249 | const struct gpio_desc *desc = dev_get_drvdata(dev); | |
250 | unsigned gpio = desc - gpio_desc; | |
251 | ssize_t status; | |
252 | ||
253 | mutex_lock(&sysfs_lock); | |
254 | ||
255 | if (!test_bit(FLAG_EXPORT, &desc->flags)) | |
256 | status = -EIO; | |
257 | else if (!test_bit(FLAG_IS_OUT, &desc->flags)) | |
258 | status = -EPERM; | |
259 | else { | |
260 | long value; | |
261 | ||
262 | status = strict_strtol(buf, 0, &value); | |
263 | if (status == 0) { | |
264 | gpio_set_value_cansleep(gpio, value != 0); | |
265 | status = size; | |
266 | } | |
267 | } | |
268 | ||
269 | mutex_unlock(&sysfs_lock); | |
270 | return status; | |
271 | } | |
272 | ||
273 | static /*const*/ DEVICE_ATTR(value, 0644, | |
274 | gpio_value_show, gpio_value_store); | |
275 | ||
276 | static const struct attribute *gpio_attrs[] = { | |
277 | &dev_attr_direction.attr, | |
278 | &dev_attr_value.attr, | |
279 | NULL, | |
280 | }; | |
281 | ||
282 | static const struct attribute_group gpio_attr_group = { | |
283 | .attrs = (struct attribute **) gpio_attrs, | |
284 | }; | |
285 | ||
286 | /* | |
287 | * /sys/class/gpio/gpiochipN/ | |
288 | * /base ... matching gpio_chip.base (N) | |
289 | * /label ... matching gpio_chip.label | |
290 | * /ngpio ... matching gpio_chip.ngpio | |
291 | */ | |
292 | ||
293 | static ssize_t chip_base_show(struct device *dev, | |
294 | struct device_attribute *attr, char *buf) | |
295 | { | |
296 | const struct gpio_chip *chip = dev_get_drvdata(dev); | |
297 | ||
298 | return sprintf(buf, "%d\n", chip->base); | |
299 | } | |
300 | static DEVICE_ATTR(base, 0444, chip_base_show, NULL); | |
301 | ||
302 | static ssize_t chip_label_show(struct device *dev, | |
303 | struct device_attribute *attr, char *buf) | |
304 | { | |
305 | const struct gpio_chip *chip = dev_get_drvdata(dev); | |
306 | ||
307 | return sprintf(buf, "%s\n", chip->label ? : ""); | |
308 | } | |
309 | static DEVICE_ATTR(label, 0444, chip_label_show, NULL); | |
310 | ||
311 | static ssize_t chip_ngpio_show(struct device *dev, | |
312 | struct device_attribute *attr, char *buf) | |
313 | { | |
314 | const struct gpio_chip *chip = dev_get_drvdata(dev); | |
315 | ||
316 | return sprintf(buf, "%u\n", chip->ngpio); | |
317 | } | |
318 | static DEVICE_ATTR(ngpio, 0444, chip_ngpio_show, NULL); | |
319 | ||
320 | static const struct attribute *gpiochip_attrs[] = { | |
321 | &dev_attr_base.attr, | |
322 | &dev_attr_label.attr, | |
323 | &dev_attr_ngpio.attr, | |
324 | NULL, | |
325 | }; | |
326 | ||
327 | static const struct attribute_group gpiochip_attr_group = { | |
328 | .attrs = (struct attribute **) gpiochip_attrs, | |
329 | }; | |
330 | ||
331 | /* | |
332 | * /sys/class/gpio/export ... write-only | |
333 | * integer N ... number of GPIO to export (full access) | |
334 | * /sys/class/gpio/unexport ... write-only | |
335 | * integer N ... number of GPIO to unexport | |
336 | */ | |
337 | static ssize_t export_store(struct class *class, const char *buf, size_t len) | |
338 | { | |
339 | long gpio; | |
340 | int status; | |
341 | ||
342 | status = strict_strtol(buf, 0, &gpio); | |
343 | if (status < 0) | |
344 | goto done; | |
345 | ||
346 | /* No extra locking here; FLAG_SYSFS just signifies that the | |
347 | * request and export were done by on behalf of userspace, so | |
348 | * they may be undone on its behalf too. | |
349 | */ | |
350 | ||
351 | status = gpio_request(gpio, "sysfs"); | |
352 | if (status < 0) | |
353 | goto done; | |
354 | ||
355 | status = gpio_export(gpio, true); | |
356 | if (status < 0) | |
357 | gpio_free(gpio); | |
358 | else | |
359 | set_bit(FLAG_SYSFS, &gpio_desc[gpio].flags); | |
360 | ||
361 | done: | |
362 | if (status) | |
363 | pr_debug("%s: status %d\n", __func__, status); | |
364 | return status ? : len; | |
365 | } | |
366 | ||
367 | static ssize_t unexport_store(struct class *class, const char *buf, size_t len) | |
368 | { | |
369 | long gpio; | |
370 | int status; | |
371 | ||
372 | status = strict_strtol(buf, 0, &gpio); | |
373 | if (status < 0) | |
374 | goto done; | |
375 | ||
376 | status = -EINVAL; | |
377 | ||
378 | /* reject bogus commands (gpio_unexport ignores them) */ | |
379 | if (!gpio_is_valid(gpio)) | |
380 | goto done; | |
381 | ||
382 | /* No extra locking here; FLAG_SYSFS just signifies that the | |
383 | * request and export were done by on behalf of userspace, so | |
384 | * they may be undone on its behalf too. | |
385 | */ | |
386 | if (test_and_clear_bit(FLAG_SYSFS, &gpio_desc[gpio].flags)) { | |
387 | status = 0; | |
388 | gpio_free(gpio); | |
389 | } | |
390 | done: | |
391 | if (status) | |
392 | pr_debug("%s: status %d\n", __func__, status); | |
393 | return status ? : len; | |
394 | } | |
395 | ||
396 | static struct class_attribute gpio_class_attrs[] = { | |
397 | __ATTR(export, 0200, NULL, export_store), | |
398 | __ATTR(unexport, 0200, NULL, unexport_store), | |
399 | __ATTR_NULL, | |
400 | }; | |
401 | ||
402 | static struct class gpio_class = { | |
403 | .name = "gpio", | |
404 | .owner = THIS_MODULE, | |
405 | ||
406 | .class_attrs = gpio_class_attrs, | |
407 | }; | |
408 | ||
409 | ||
410 | /** | |
411 | * gpio_export - export a GPIO through sysfs | |
412 | * @gpio: gpio to make available, already requested | |
413 | * @direction_may_change: true if userspace may change gpio direction | |
414 | * Context: arch_initcall or later | |
415 | * | |
416 | * When drivers want to make a GPIO accessible to userspace after they | |
417 | * have requested it -- perhaps while debugging, or as part of their | |
418 | * public interface -- they may use this routine. If the GPIO can | |
419 | * change direction (some can't) and the caller allows it, userspace | |
420 | * will see "direction" sysfs attribute which may be used to change | |
421 | * the gpio's direction. A "value" attribute will always be provided. | |
422 | * | |
423 | * Returns zero on success, else an error. | |
424 | */ | |
425 | int gpio_export(unsigned gpio, bool direction_may_change) | |
426 | { | |
427 | unsigned long flags; | |
428 | struct gpio_desc *desc; | |
429 | int status = -EINVAL; | |
430 | ||
431 | /* can't export until sysfs is available ... */ | |
432 | if (!gpio_class.p) { | |
433 | pr_debug("%s: called too early!\n", __func__); | |
434 | return -ENOENT; | |
435 | } | |
436 | ||
437 | if (!gpio_is_valid(gpio)) | |
438 | goto done; | |
439 | ||
440 | mutex_lock(&sysfs_lock); | |
441 | ||
442 | spin_lock_irqsave(&gpio_lock, flags); | |
443 | desc = &gpio_desc[gpio]; | |
444 | if (test_bit(FLAG_REQUESTED, &desc->flags) | |
445 | && !test_bit(FLAG_EXPORT, &desc->flags)) { | |
446 | status = 0; | |
447 | if (!desc->chip->direction_input | |
448 | || !desc->chip->direction_output) | |
449 | direction_may_change = false; | |
450 | } | |
451 | spin_unlock_irqrestore(&gpio_lock, flags); | |
452 | ||
453 | if (status == 0) { | |
454 | struct device *dev; | |
455 | ||
456 | dev = device_create(&gpio_class, desc->chip->dev, MKDEV(0, 0), | |
457 | desc, "gpio%d", gpio); | |
458 | if (dev) { | |
459 | if (direction_may_change) | |
460 | status = sysfs_create_group(&dev->kobj, | |
461 | &gpio_attr_group); | |
462 | else | |
463 | status = device_create_file(dev, | |
464 | &dev_attr_value); | |
465 | if (status != 0) | |
466 | device_unregister(dev); | |
467 | } else | |
468 | status = -ENODEV; | |
469 | if (status == 0) | |
470 | set_bit(FLAG_EXPORT, &desc->flags); | |
471 | } | |
472 | ||
473 | mutex_unlock(&sysfs_lock); | |
474 | ||
475 | done: | |
476 | if (status) | |
477 | pr_debug("%s: gpio%d status %d\n", __func__, gpio, status); | |
478 | ||
479 | return status; | |
480 | } | |
481 | EXPORT_SYMBOL_GPL(gpio_export); | |
482 | ||
483 | static int match_export(struct device *dev, void *data) | |
484 | { | |
485 | return dev_get_drvdata(dev) == data; | |
486 | } | |
487 | ||
488 | /** | |
489 | * gpio_unexport - reverse effect of gpio_export() | |
490 | * @gpio: gpio to make unavailable | |
491 | * | |
492 | * This is implicit on gpio_free(). | |
493 | */ | |
494 | void gpio_unexport(unsigned gpio) | |
495 | { | |
496 | struct gpio_desc *desc; | |
497 | int status = -EINVAL; | |
498 | ||
499 | if (!gpio_is_valid(gpio)) | |
500 | goto done; | |
501 | ||
502 | mutex_lock(&sysfs_lock); | |
503 | ||
504 | desc = &gpio_desc[gpio]; | |
505 | if (test_bit(FLAG_EXPORT, &desc->flags)) { | |
506 | struct device *dev = NULL; | |
507 | ||
508 | dev = class_find_device(&gpio_class, NULL, desc, match_export); | |
509 | if (dev) { | |
510 | clear_bit(FLAG_EXPORT, &desc->flags); | |
511 | put_device(dev); | |
512 | device_unregister(dev); | |
513 | status = 0; | |
514 | } else | |
515 | status = -ENODEV; | |
516 | } | |
517 | ||
518 | mutex_unlock(&sysfs_lock); | |
519 | done: | |
520 | if (status) | |
521 | pr_debug("%s: gpio%d status %d\n", __func__, gpio, status); | |
522 | } | |
523 | EXPORT_SYMBOL_GPL(gpio_unexport); | |
524 | ||
525 | static int gpiochip_export(struct gpio_chip *chip) | |
526 | { | |
527 | int status; | |
528 | struct device *dev; | |
529 | ||
530 | /* Many systems register gpio chips for SOC support very early, | |
531 | * before driver model support is available. In those cases we | |
532 | * export this later, in gpiolib_sysfs_init() ... here we just | |
533 | * verify that _some_ field of gpio_class got initialized. | |
534 | */ | |
535 | if (!gpio_class.p) | |
536 | return 0; | |
537 | ||
538 | /* use chip->base for the ID; it's already known to be unique */ | |
539 | mutex_lock(&sysfs_lock); | |
540 | dev = device_create(&gpio_class, chip->dev, MKDEV(0, 0), chip, | |
541 | "gpiochip%d", chip->base); | |
542 | if (dev) { | |
543 | status = sysfs_create_group(&dev->kobj, | |
544 | &gpiochip_attr_group); | |
545 | } else | |
546 | status = -ENODEV; | |
547 | chip->exported = (status == 0); | |
548 | mutex_unlock(&sysfs_lock); | |
549 | ||
550 | if (status) { | |
551 | unsigned long flags; | |
552 | unsigned gpio; | |
553 | ||
554 | spin_lock_irqsave(&gpio_lock, flags); | |
555 | gpio = chip->base; | |
556 | while (gpio_desc[gpio].chip == chip) | |
557 | gpio_desc[gpio++].chip = NULL; | |
558 | spin_unlock_irqrestore(&gpio_lock, flags); | |
559 | ||
560 | pr_debug("%s: chip %s status %d\n", __func__, | |
561 | chip->label, status); | |
562 | } | |
563 | ||
564 | return status; | |
565 | } | |
566 | ||
567 | static void gpiochip_unexport(struct gpio_chip *chip) | |
568 | { | |
569 | int status; | |
570 | struct device *dev; | |
571 | ||
572 | mutex_lock(&sysfs_lock); | |
573 | dev = class_find_device(&gpio_class, NULL, chip, match_export); | |
574 | if (dev) { | |
575 | put_device(dev); | |
576 | device_unregister(dev); | |
577 | chip->exported = 0; | |
578 | status = 0; | |
579 | } else | |
580 | status = -ENODEV; | |
581 | mutex_unlock(&sysfs_lock); | |
582 | ||
583 | if (status) | |
584 | pr_debug("%s: chip %s status %d\n", __func__, | |
585 | chip->label, status); | |
586 | } | |
587 | ||
588 | static int __init gpiolib_sysfs_init(void) | |
589 | { | |
590 | int status; | |
591 | unsigned long flags; | |
592 | unsigned gpio; | |
593 | ||
594 | status = class_register(&gpio_class); | |
595 | if (status < 0) | |
596 | return status; | |
597 | ||
598 | /* Scan and register the gpio_chips which registered very | |
599 | * early (e.g. before the class_register above was called). | |
600 | * | |
601 | * We run before arch_initcall() so chip->dev nodes can have | |
602 | * registered, and so arch_initcall() can always gpio_export(). | |
603 | */ | |
604 | spin_lock_irqsave(&gpio_lock, flags); | |
605 | for (gpio = 0; gpio < ARCH_NR_GPIOS; gpio++) { | |
606 | struct gpio_chip *chip; | |
607 | ||
608 | chip = gpio_desc[gpio].chip; | |
609 | if (!chip || chip->exported) | |
610 | continue; | |
611 | ||
612 | spin_unlock_irqrestore(&gpio_lock, flags); | |
613 | status = gpiochip_export(chip); | |
614 | spin_lock_irqsave(&gpio_lock, flags); | |
615 | } | |
616 | spin_unlock_irqrestore(&gpio_lock, flags); | |
617 | ||
618 | ||
619 | return status; | |
620 | } | |
621 | postcore_initcall(gpiolib_sysfs_init); | |
622 | ||
623 | #else | |
624 | static inline int gpiochip_export(struct gpio_chip *chip) | |
625 | { | |
626 | return 0; | |
627 | } | |
628 | ||
629 | static inline void gpiochip_unexport(struct gpio_chip *chip) | |
630 | { | |
631 | } | |
632 | ||
633 | #endif /* CONFIG_GPIO_SYSFS */ | |
634 | ||
d2876d08 DB |
635 | /** |
636 | * gpiochip_add() - register a gpio_chip | |
637 | * @chip: the chip to register, with chip->base initialized | |
638 | * Context: potentially before irqs or kmalloc will work | |
639 | * | |
640 | * Returns a negative errno if the chip can't be registered, such as | |
641 | * because the chip->base is invalid or already associated with a | |
642 | * different chip. Otherwise it returns zero as a success code. | |
8d0aab2f | 643 | * |
d8f388d8 DB |
644 | * When gpiochip_add() is called very early during boot, so that GPIOs |
645 | * can be freely used, the chip->dev device must be registered before | |
646 | * the gpio framework's arch_initcall(). Otherwise sysfs initialization | |
647 | * for GPIOs will fail rudely. | |
648 | * | |
8d0aab2f AV |
649 | * If chip->base is negative, this requests dynamic assignment of |
650 | * a range of valid GPIOs. | |
d2876d08 DB |
651 | */ |
652 | int gpiochip_add(struct gpio_chip *chip) | |
653 | { | |
654 | unsigned long flags; | |
655 | int status = 0; | |
656 | unsigned id; | |
8d0aab2f | 657 | int base = chip->base; |
d2876d08 | 658 | |
bff5fda9 | 659 | if ((!gpio_is_valid(base) || !gpio_is_valid(base + chip->ngpio - 1)) |
8d0aab2f | 660 | && base >= 0) { |
d2876d08 DB |
661 | status = -EINVAL; |
662 | goto fail; | |
663 | } | |
664 | ||
665 | spin_lock_irqsave(&gpio_lock, flags); | |
666 | ||
8d0aab2f AV |
667 | if (base < 0) { |
668 | base = gpiochip_find_base(chip->ngpio); | |
669 | if (base < 0) { | |
670 | status = base; | |
d8f388d8 | 671 | goto unlock; |
8d0aab2f AV |
672 | } |
673 | chip->base = base; | |
674 | } | |
675 | ||
d2876d08 | 676 | /* these GPIO numbers must not be managed by another gpio_chip */ |
8d0aab2f | 677 | for (id = base; id < base + chip->ngpio; id++) { |
d2876d08 DB |
678 | if (gpio_desc[id].chip != NULL) { |
679 | status = -EBUSY; | |
680 | break; | |
681 | } | |
682 | } | |
683 | if (status == 0) { | |
8d0aab2f | 684 | for (id = base; id < base + chip->ngpio; id++) { |
d2876d08 | 685 | gpio_desc[id].chip = chip; |
d8f388d8 DB |
686 | |
687 | /* REVISIT: most hardware initializes GPIOs as | |
688 | * inputs (often with pullups enabled) so power | |
689 | * usage is minimized. Linux code should set the | |
690 | * gpio direction first thing; but until it does, | |
691 | * we may expose the wrong direction in sysfs. | |
692 | */ | |
693 | gpio_desc[id].flags = !chip->direction_input | |
694 | ? (1 << FLAG_IS_OUT) | |
695 | : 0; | |
d2876d08 DB |
696 | } |
697 | } | |
698 | ||
d8f388d8 | 699 | unlock: |
d2876d08 | 700 | spin_unlock_irqrestore(&gpio_lock, flags); |
d8f388d8 DB |
701 | if (status == 0) |
702 | status = gpiochip_export(chip); | |
d2876d08 DB |
703 | fail: |
704 | /* failures here can mean systems won't boot... */ | |
705 | if (status) | |
706 | pr_err("gpiochip_add: gpios %d..%d (%s) not registered\n", | |
bff5fda9 | 707 | chip->base, chip->base + chip->ngpio - 1, |
d2876d08 DB |
708 | chip->label ? : "generic"); |
709 | return status; | |
710 | } | |
711 | EXPORT_SYMBOL_GPL(gpiochip_add); | |
712 | ||
713 | /** | |
714 | * gpiochip_remove() - unregister a gpio_chip | |
715 | * @chip: the chip to unregister | |
716 | * | |
717 | * A gpio_chip with any GPIOs still requested may not be removed. | |
718 | */ | |
719 | int gpiochip_remove(struct gpio_chip *chip) | |
720 | { | |
721 | unsigned long flags; | |
722 | int status = 0; | |
723 | unsigned id; | |
724 | ||
725 | spin_lock_irqsave(&gpio_lock, flags); | |
726 | ||
727 | for (id = chip->base; id < chip->base + chip->ngpio; id++) { | |
728 | if (test_bit(FLAG_REQUESTED, &gpio_desc[id].flags)) { | |
729 | status = -EBUSY; | |
730 | break; | |
731 | } | |
732 | } | |
733 | if (status == 0) { | |
734 | for (id = chip->base; id < chip->base + chip->ngpio; id++) | |
735 | gpio_desc[id].chip = NULL; | |
736 | } | |
737 | ||
738 | spin_unlock_irqrestore(&gpio_lock, flags); | |
d8f388d8 DB |
739 | |
740 | if (status == 0) | |
741 | gpiochip_unexport(chip); | |
742 | ||
d2876d08 DB |
743 | return status; |
744 | } | |
745 | EXPORT_SYMBOL_GPL(gpiochip_remove); | |
746 | ||
747 | ||
748 | /* These "optional" allocation calls help prevent drivers from stomping | |
749 | * on each other, and help provide better diagnostics in debugfs. | |
750 | * They're called even less than the "set direction" calls. | |
751 | */ | |
752 | int gpio_request(unsigned gpio, const char *label) | |
753 | { | |
754 | struct gpio_desc *desc; | |
755 | int status = -EINVAL; | |
756 | unsigned long flags; | |
757 | ||
758 | spin_lock_irqsave(&gpio_lock, flags); | |
759 | ||
e6de1808 | 760 | if (!gpio_is_valid(gpio)) |
d2876d08 DB |
761 | goto done; |
762 | desc = &gpio_desc[gpio]; | |
763 | if (desc->chip == NULL) | |
764 | goto done; | |
765 | ||
438d8908 GL |
766 | if (!try_module_get(desc->chip->owner)) |
767 | goto done; | |
768 | ||
d2876d08 DB |
769 | /* NOTE: gpio_request() can be called in early boot, |
770 | * before IRQs are enabled. | |
771 | */ | |
772 | ||
773 | if (test_and_set_bit(FLAG_REQUESTED, &desc->flags) == 0) { | |
774 | desc_set_label(desc, label ? : "?"); | |
775 | status = 0; | |
438d8908 | 776 | } else { |
d2876d08 | 777 | status = -EBUSY; |
438d8908 GL |
778 | module_put(desc->chip->owner); |
779 | } | |
d2876d08 DB |
780 | |
781 | done: | |
782 | if (status) | |
783 | pr_debug("gpio_request: gpio-%d (%s) status %d\n", | |
784 | gpio, label ? : "?", status); | |
785 | spin_unlock_irqrestore(&gpio_lock, flags); | |
786 | return status; | |
787 | } | |
788 | EXPORT_SYMBOL_GPL(gpio_request); | |
789 | ||
790 | void gpio_free(unsigned gpio) | |
791 | { | |
792 | unsigned long flags; | |
793 | struct gpio_desc *desc; | |
794 | ||
e6de1808 | 795 | if (!gpio_is_valid(gpio)) { |
d2876d08 DB |
796 | WARN_ON(extra_checks); |
797 | return; | |
798 | } | |
799 | ||
d8f388d8 DB |
800 | gpio_unexport(gpio); |
801 | ||
d2876d08 DB |
802 | spin_lock_irqsave(&gpio_lock, flags); |
803 | ||
804 | desc = &gpio_desc[gpio]; | |
438d8908 | 805 | if (desc->chip && test_and_clear_bit(FLAG_REQUESTED, &desc->flags)) { |
d2876d08 | 806 | desc_set_label(desc, NULL); |
438d8908 GL |
807 | module_put(desc->chip->owner); |
808 | } else | |
d2876d08 DB |
809 | WARN_ON(extra_checks); |
810 | ||
811 | spin_unlock_irqrestore(&gpio_lock, flags); | |
812 | } | |
813 | EXPORT_SYMBOL_GPL(gpio_free); | |
814 | ||
815 | ||
816 | /** | |
817 | * gpiochip_is_requested - return string iff signal was requested | |
818 | * @chip: controller managing the signal | |
819 | * @offset: of signal within controller's 0..(ngpio - 1) range | |
820 | * | |
821 | * Returns NULL if the GPIO is not currently requested, else a string. | |
822 | * If debugfs support is enabled, the string returned is the label passed | |
823 | * to gpio_request(); otherwise it is a meaningless constant. | |
824 | * | |
825 | * This function is for use by GPIO controller drivers. The label can | |
826 | * help with diagnostics, and knowing that the signal is used as a GPIO | |
827 | * can help avoid accidentally multiplexing it to another controller. | |
828 | */ | |
829 | const char *gpiochip_is_requested(struct gpio_chip *chip, unsigned offset) | |
830 | { | |
831 | unsigned gpio = chip->base + offset; | |
832 | ||
e6de1808 | 833 | if (!gpio_is_valid(gpio) || gpio_desc[gpio].chip != chip) |
d2876d08 DB |
834 | return NULL; |
835 | if (test_bit(FLAG_REQUESTED, &gpio_desc[gpio].flags) == 0) | |
836 | return NULL; | |
837 | #ifdef CONFIG_DEBUG_FS | |
838 | return gpio_desc[gpio].label; | |
839 | #else | |
840 | return "?"; | |
841 | #endif | |
842 | } | |
843 | EXPORT_SYMBOL_GPL(gpiochip_is_requested); | |
844 | ||
845 | ||
846 | /* Drivers MUST set GPIO direction before making get/set calls. In | |
847 | * some cases this is done in early boot, before IRQs are enabled. | |
848 | * | |
849 | * As a rule these aren't called more than once (except for drivers | |
850 | * using the open-drain emulation idiom) so these are natural places | |
851 | * to accumulate extra debugging checks. Note that we can't (yet) | |
852 | * rely on gpio_request() having been called beforehand. | |
853 | */ | |
854 | ||
855 | int gpio_direction_input(unsigned gpio) | |
856 | { | |
857 | unsigned long flags; | |
858 | struct gpio_chip *chip; | |
859 | struct gpio_desc *desc = &gpio_desc[gpio]; | |
860 | int status = -EINVAL; | |
861 | ||
862 | spin_lock_irqsave(&gpio_lock, flags); | |
863 | ||
e6de1808 | 864 | if (!gpio_is_valid(gpio)) |
d2876d08 DB |
865 | goto fail; |
866 | chip = desc->chip; | |
867 | if (!chip || !chip->get || !chip->direction_input) | |
868 | goto fail; | |
869 | gpio -= chip->base; | |
870 | if (gpio >= chip->ngpio) | |
871 | goto fail; | |
872 | gpio_ensure_requested(desc); | |
873 | ||
874 | /* now we know the gpio is valid and chip won't vanish */ | |
875 | ||
876 | spin_unlock_irqrestore(&gpio_lock, flags); | |
877 | ||
878 | might_sleep_if(extra_checks && chip->can_sleep); | |
879 | ||
880 | status = chip->direction_input(chip, gpio); | |
881 | if (status == 0) | |
882 | clear_bit(FLAG_IS_OUT, &desc->flags); | |
883 | return status; | |
884 | fail: | |
885 | spin_unlock_irqrestore(&gpio_lock, flags); | |
886 | if (status) | |
887 | pr_debug("%s: gpio-%d status %d\n", | |
145980a0 | 888 | __func__, gpio, status); |
d2876d08 DB |
889 | return status; |
890 | } | |
891 | EXPORT_SYMBOL_GPL(gpio_direction_input); | |
892 | ||
893 | int gpio_direction_output(unsigned gpio, int value) | |
894 | { | |
895 | unsigned long flags; | |
896 | struct gpio_chip *chip; | |
897 | struct gpio_desc *desc = &gpio_desc[gpio]; | |
898 | int status = -EINVAL; | |
899 | ||
900 | spin_lock_irqsave(&gpio_lock, flags); | |
901 | ||
e6de1808 | 902 | if (!gpio_is_valid(gpio)) |
d2876d08 DB |
903 | goto fail; |
904 | chip = desc->chip; | |
905 | if (!chip || !chip->set || !chip->direction_output) | |
906 | goto fail; | |
907 | gpio -= chip->base; | |
908 | if (gpio >= chip->ngpio) | |
909 | goto fail; | |
910 | gpio_ensure_requested(desc); | |
911 | ||
912 | /* now we know the gpio is valid and chip won't vanish */ | |
913 | ||
914 | spin_unlock_irqrestore(&gpio_lock, flags); | |
915 | ||
916 | might_sleep_if(extra_checks && chip->can_sleep); | |
917 | ||
918 | status = chip->direction_output(chip, gpio, value); | |
919 | if (status == 0) | |
920 | set_bit(FLAG_IS_OUT, &desc->flags); | |
921 | return status; | |
922 | fail: | |
923 | spin_unlock_irqrestore(&gpio_lock, flags); | |
924 | if (status) | |
925 | pr_debug("%s: gpio-%d status %d\n", | |
145980a0 | 926 | __func__, gpio, status); |
d2876d08 DB |
927 | return status; |
928 | } | |
929 | EXPORT_SYMBOL_GPL(gpio_direction_output); | |
930 | ||
931 | ||
932 | /* I/O calls are only valid after configuration completed; the relevant | |
933 | * "is this a valid GPIO" error checks should already have been done. | |
934 | * | |
935 | * "Get" operations are often inlinable as reading a pin value register, | |
936 | * and masking the relevant bit in that register. | |
937 | * | |
938 | * When "set" operations are inlinable, they involve writing that mask to | |
939 | * one register to set a low value, or a different register to set it high. | |
940 | * Otherwise locking is needed, so there may be little value to inlining. | |
941 | * | |
942 | *------------------------------------------------------------------------ | |
943 | * | |
944 | * IMPORTANT!!! The hot paths -- get/set value -- assume that callers | |
945 | * have requested the GPIO. That can include implicit requesting by | |
946 | * a direction setting call. Marking a gpio as requested locks its chip | |
947 | * in memory, guaranteeing that these table lookups need no more locking | |
948 | * and that gpiochip_remove() will fail. | |
949 | * | |
950 | * REVISIT when debugging, consider adding some instrumentation to ensure | |
951 | * that the GPIO was actually requested. | |
952 | */ | |
953 | ||
954 | /** | |
955 | * __gpio_get_value() - return a gpio's value | |
956 | * @gpio: gpio whose value will be returned | |
957 | * Context: any | |
958 | * | |
959 | * This is used directly or indirectly to implement gpio_get_value(). | |
960 | * It returns the zero or nonzero value provided by the associated | |
961 | * gpio_chip.get() method; or zero if no such method is provided. | |
962 | */ | |
963 | int __gpio_get_value(unsigned gpio) | |
964 | { | |
965 | struct gpio_chip *chip; | |
966 | ||
967 | chip = gpio_to_chip(gpio); | |
968 | WARN_ON(extra_checks && chip->can_sleep); | |
969 | return chip->get ? chip->get(chip, gpio - chip->base) : 0; | |
970 | } | |
971 | EXPORT_SYMBOL_GPL(__gpio_get_value); | |
972 | ||
973 | /** | |
974 | * __gpio_set_value() - assign a gpio's value | |
975 | * @gpio: gpio whose value will be assigned | |
976 | * @value: value to assign | |
977 | * Context: any | |
978 | * | |
979 | * This is used directly or indirectly to implement gpio_set_value(). | |
980 | * It invokes the associated gpio_chip.set() method. | |
981 | */ | |
982 | void __gpio_set_value(unsigned gpio, int value) | |
983 | { | |
984 | struct gpio_chip *chip; | |
985 | ||
986 | chip = gpio_to_chip(gpio); | |
987 | WARN_ON(extra_checks && chip->can_sleep); | |
988 | chip->set(chip, gpio - chip->base, value); | |
989 | } | |
990 | EXPORT_SYMBOL_GPL(__gpio_set_value); | |
991 | ||
992 | /** | |
993 | * __gpio_cansleep() - report whether gpio value access will sleep | |
994 | * @gpio: gpio in question | |
995 | * Context: any | |
996 | * | |
997 | * This is used directly or indirectly to implement gpio_cansleep(). It | |
998 | * returns nonzero if access reading or writing the GPIO value can sleep. | |
999 | */ | |
1000 | int __gpio_cansleep(unsigned gpio) | |
1001 | { | |
1002 | struct gpio_chip *chip; | |
1003 | ||
1004 | /* only call this on GPIOs that are valid! */ | |
1005 | chip = gpio_to_chip(gpio); | |
1006 | ||
1007 | return chip->can_sleep; | |
1008 | } | |
1009 | EXPORT_SYMBOL_GPL(__gpio_cansleep); | |
1010 | ||
1011 | ||
1012 | ||
1013 | /* There's no value in making it easy to inline GPIO calls that may sleep. | |
1014 | * Common examples include ones connected to I2C or SPI chips. | |
1015 | */ | |
1016 | ||
1017 | int gpio_get_value_cansleep(unsigned gpio) | |
1018 | { | |
1019 | struct gpio_chip *chip; | |
1020 | ||
1021 | might_sleep_if(extra_checks); | |
1022 | chip = gpio_to_chip(gpio); | |
1023 | return chip->get(chip, gpio - chip->base); | |
1024 | } | |
1025 | EXPORT_SYMBOL_GPL(gpio_get_value_cansleep); | |
1026 | ||
1027 | void gpio_set_value_cansleep(unsigned gpio, int value) | |
1028 | { | |
1029 | struct gpio_chip *chip; | |
1030 | ||
1031 | might_sleep_if(extra_checks); | |
1032 | chip = gpio_to_chip(gpio); | |
1033 | chip->set(chip, gpio - chip->base, value); | |
1034 | } | |
1035 | EXPORT_SYMBOL_GPL(gpio_set_value_cansleep); | |
1036 | ||
1037 | ||
1038 | #ifdef CONFIG_DEBUG_FS | |
1039 | ||
d2876d08 DB |
1040 | static void gpiolib_dbg_show(struct seq_file *s, struct gpio_chip *chip) |
1041 | { | |
1042 | unsigned i; | |
1043 | unsigned gpio = chip->base; | |
1044 | struct gpio_desc *gdesc = &gpio_desc[gpio]; | |
1045 | int is_out; | |
1046 | ||
1047 | for (i = 0; i < chip->ngpio; i++, gpio++, gdesc++) { | |
1048 | if (!test_bit(FLAG_REQUESTED, &gdesc->flags)) | |
1049 | continue; | |
1050 | ||
1051 | is_out = test_bit(FLAG_IS_OUT, &gdesc->flags); | |
1052 | seq_printf(s, " gpio-%-3d (%-12s) %s %s", | |
1053 | gpio, gdesc->label, | |
1054 | is_out ? "out" : "in ", | |
1055 | chip->get | |
1056 | ? (chip->get(chip, i) ? "hi" : "lo") | |
1057 | : "? "); | |
1058 | ||
1059 | if (!is_out) { | |
1060 | int irq = gpio_to_irq(gpio); | |
1061 | struct irq_desc *desc = irq_desc + irq; | |
1062 | ||
1063 | /* This races with request_irq(), set_irq_type(), | |
1064 | * and set_irq_wake() ... but those are "rare". | |
1065 | * | |
1066 | * More significantly, trigger type flags aren't | |
1067 | * currently maintained by genirq. | |
1068 | */ | |
1069 | if (irq >= 0 && desc->action) { | |
1070 | char *trigger; | |
1071 | ||
1072 | switch (desc->status & IRQ_TYPE_SENSE_MASK) { | |
1073 | case IRQ_TYPE_NONE: | |
1074 | trigger = "(default)"; | |
1075 | break; | |
1076 | case IRQ_TYPE_EDGE_FALLING: | |
1077 | trigger = "edge-falling"; | |
1078 | break; | |
1079 | case IRQ_TYPE_EDGE_RISING: | |
1080 | trigger = "edge-rising"; | |
1081 | break; | |
1082 | case IRQ_TYPE_EDGE_BOTH: | |
1083 | trigger = "edge-both"; | |
1084 | break; | |
1085 | case IRQ_TYPE_LEVEL_HIGH: | |
1086 | trigger = "level-high"; | |
1087 | break; | |
1088 | case IRQ_TYPE_LEVEL_LOW: | |
1089 | trigger = "level-low"; | |
1090 | break; | |
1091 | default: | |
1092 | trigger = "?trigger?"; | |
1093 | break; | |
1094 | } | |
1095 | ||
1096 | seq_printf(s, " irq-%d %s%s", | |
1097 | irq, trigger, | |
1098 | (desc->status & IRQ_WAKEUP) | |
1099 | ? " wakeup" : ""); | |
1100 | } | |
1101 | } | |
1102 | ||
1103 | seq_printf(s, "\n"); | |
1104 | } | |
1105 | } | |
1106 | ||
1107 | static int gpiolib_show(struct seq_file *s, void *unused) | |
1108 | { | |
1109 | struct gpio_chip *chip = NULL; | |
1110 | unsigned gpio; | |
1111 | int started = 0; | |
1112 | ||
1113 | /* REVISIT this isn't locked against gpio_chip removal ... */ | |
1114 | ||
e6de1808 | 1115 | for (gpio = 0; gpio_is_valid(gpio); gpio++) { |
d8f388d8 DB |
1116 | struct device *dev; |
1117 | ||
d2876d08 DB |
1118 | if (chip == gpio_desc[gpio].chip) |
1119 | continue; | |
1120 | chip = gpio_desc[gpio].chip; | |
1121 | if (!chip) | |
1122 | continue; | |
1123 | ||
d8f388d8 | 1124 | seq_printf(s, "%sGPIOs %d-%d", |
d2876d08 | 1125 | started ? "\n" : "", |
d8f388d8 DB |
1126 | chip->base, chip->base + chip->ngpio - 1); |
1127 | dev = chip->dev; | |
1128 | if (dev) | |
1129 | seq_printf(s, ", %s/%s", | |
1130 | dev->bus ? dev->bus->name : "no-bus", | |
1131 | dev->bus_id); | |
1132 | if (chip->label) | |
1133 | seq_printf(s, ", %s", chip->label); | |
1134 | if (chip->can_sleep) | |
1135 | seq_printf(s, ", can sleep"); | |
1136 | seq_printf(s, ":\n"); | |
1137 | ||
d2876d08 DB |
1138 | started = 1; |
1139 | if (chip->dbg_show) | |
1140 | chip->dbg_show(s, chip); | |
1141 | else | |
1142 | gpiolib_dbg_show(s, chip); | |
1143 | } | |
1144 | return 0; | |
1145 | } | |
1146 | ||
1147 | static int gpiolib_open(struct inode *inode, struct file *file) | |
1148 | { | |
1149 | return single_open(file, gpiolib_show, NULL); | |
1150 | } | |
1151 | ||
1152 | static struct file_operations gpiolib_operations = { | |
1153 | .open = gpiolib_open, | |
1154 | .read = seq_read, | |
1155 | .llseek = seq_lseek, | |
1156 | .release = single_release, | |
1157 | }; | |
1158 | ||
1159 | static int __init gpiolib_debugfs_init(void) | |
1160 | { | |
1161 | /* /sys/kernel/debug/gpio */ | |
1162 | (void) debugfs_create_file("gpio", S_IFREG | S_IRUGO, | |
1163 | NULL, NULL, &gpiolib_operations); | |
1164 | return 0; | |
1165 | } | |
1166 | subsys_initcall(gpiolib_debugfs_init); | |
1167 | ||
1168 | #endif /* DEBUG_FS */ |