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1 | /* |
2 | * nvmem framework core. | |
3 | * | |
4 | * Copyright (C) 2015 Srinivas Kandagatla <srinivas.kandagatla@linaro.org> | |
5 | * Copyright (C) 2013 Maxime Ripard <maxime.ripard@free-electrons.com> | |
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 version 2 and | |
9 | * only version 2 as published by the Free Software Foundation. | |
10 | * | |
11 | * This program is distributed in the hope that it will be useful, | |
12 | * but WITHOUT ANY WARRANTY; without even the implied warranty of | |
13 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the | |
14 | * GNU General Public License for more details. | |
15 | */ | |
16 | ||
17 | #include <linux/device.h> | |
18 | #include <linux/export.h> | |
19 | #include <linux/fs.h> | |
20 | #include <linux/idr.h> | |
21 | #include <linux/init.h> | |
22 | #include <linux/module.h> | |
23 | #include <linux/nvmem-consumer.h> | |
24 | #include <linux/nvmem-provider.h> | |
25 | #include <linux/of.h> | |
26 | #include <linux/regmap.h> | |
27 | #include <linux/slab.h> | |
28 | ||
29 | struct nvmem_device { | |
30 | const char *name; | |
31 | struct regmap *regmap; | |
32 | struct module *owner; | |
33 | struct device dev; | |
34 | int stride; | |
35 | int word_size; | |
36 | int ncells; | |
37 | int id; | |
38 | int users; | |
39 | size_t size; | |
40 | bool read_only; | |
41 | }; | |
42 | ||
43 | struct nvmem_cell { | |
44 | const char *name; | |
45 | int offset; | |
46 | int bytes; | |
47 | int bit_offset; | |
48 | int nbits; | |
49 | struct nvmem_device *nvmem; | |
50 | struct list_head node; | |
51 | }; | |
52 | ||
53 | static DEFINE_MUTEX(nvmem_mutex); | |
54 | static DEFINE_IDA(nvmem_ida); | |
55 | ||
56 | static LIST_HEAD(nvmem_cells); | |
57 | static DEFINE_MUTEX(nvmem_cells_mutex); | |
58 | ||
59 | #define to_nvmem_device(d) container_of(d, struct nvmem_device, dev) | |
60 | ||
61 | static ssize_t bin_attr_nvmem_read(struct file *filp, struct kobject *kobj, | |
62 | struct bin_attribute *attr, | |
63 | char *buf, loff_t pos, size_t count) | |
64 | { | |
65 | struct device *dev = container_of(kobj, struct device, kobj); | |
66 | struct nvmem_device *nvmem = to_nvmem_device(dev); | |
67 | int rc; | |
68 | ||
69 | /* Stop the user from reading */ | |
70 | if (pos > nvmem->size) | |
71 | return 0; | |
72 | ||
73 | if (pos + count > nvmem->size) | |
74 | count = nvmem->size - pos; | |
75 | ||
76 | count = round_down(count, nvmem->word_size); | |
77 | ||
78 | rc = regmap_raw_read(nvmem->regmap, pos, buf, count); | |
79 | ||
80 | if (IS_ERR_VALUE(rc)) | |
81 | return rc; | |
82 | ||
83 | return count; | |
84 | } | |
85 | ||
86 | static ssize_t bin_attr_nvmem_write(struct file *filp, struct kobject *kobj, | |
87 | struct bin_attribute *attr, | |
88 | char *buf, loff_t pos, size_t count) | |
89 | { | |
90 | struct device *dev = container_of(kobj, struct device, kobj); | |
91 | struct nvmem_device *nvmem = to_nvmem_device(dev); | |
92 | int rc; | |
93 | ||
94 | /* Stop the user from writing */ | |
95 | if (pos > nvmem->size) | |
96 | return 0; | |
97 | ||
98 | if (pos + count > nvmem->size) | |
99 | count = nvmem->size - pos; | |
100 | ||
101 | count = round_down(count, nvmem->word_size); | |
102 | ||
103 | rc = regmap_raw_write(nvmem->regmap, pos, buf, count); | |
104 | ||
105 | if (IS_ERR_VALUE(rc)) | |
106 | return rc; | |
107 | ||
108 | return count; | |
109 | } | |
110 | ||
111 | /* default read/write permissions */ | |
112 | static struct bin_attribute bin_attr_rw_nvmem = { | |
113 | .attr = { | |
114 | .name = "nvmem", | |
115 | .mode = S_IWUSR | S_IRUGO, | |
116 | }, | |
117 | .read = bin_attr_nvmem_read, | |
118 | .write = bin_attr_nvmem_write, | |
119 | }; | |
120 | ||
121 | static struct bin_attribute *nvmem_bin_rw_attributes[] = { | |
122 | &bin_attr_rw_nvmem, | |
123 | NULL, | |
124 | }; | |
125 | ||
126 | static const struct attribute_group nvmem_bin_rw_group = { | |
127 | .bin_attrs = nvmem_bin_rw_attributes, | |
128 | }; | |
129 | ||
130 | static const struct attribute_group *nvmem_rw_dev_groups[] = { | |
131 | &nvmem_bin_rw_group, | |
132 | NULL, | |
133 | }; | |
134 | ||
135 | /* read only permission */ | |
136 | static struct bin_attribute bin_attr_ro_nvmem = { | |
137 | .attr = { | |
138 | .name = "nvmem", | |
139 | .mode = S_IRUGO, | |
140 | }, | |
141 | .read = bin_attr_nvmem_read, | |
142 | }; | |
143 | ||
144 | static struct bin_attribute *nvmem_bin_ro_attributes[] = { | |
145 | &bin_attr_ro_nvmem, | |
146 | NULL, | |
147 | }; | |
148 | ||
149 | static const struct attribute_group nvmem_bin_ro_group = { | |
150 | .bin_attrs = nvmem_bin_ro_attributes, | |
151 | }; | |
152 | ||
153 | static const struct attribute_group *nvmem_ro_dev_groups[] = { | |
154 | &nvmem_bin_ro_group, | |
155 | NULL, | |
156 | }; | |
157 | ||
158 | static void nvmem_release(struct device *dev) | |
159 | { | |
160 | struct nvmem_device *nvmem = to_nvmem_device(dev); | |
161 | ||
162 | ida_simple_remove(&nvmem_ida, nvmem->id); | |
163 | kfree(nvmem); | |
164 | } | |
165 | ||
166 | static const struct device_type nvmem_provider_type = { | |
167 | .release = nvmem_release, | |
168 | }; | |
169 | ||
170 | static struct bus_type nvmem_bus_type = { | |
171 | .name = "nvmem", | |
172 | }; | |
173 | ||
174 | static int of_nvmem_match(struct device *dev, void *nvmem_np) | |
175 | { | |
176 | return dev->of_node == nvmem_np; | |
177 | } | |
178 | ||
179 | static struct nvmem_device *of_nvmem_find(struct device_node *nvmem_np) | |
180 | { | |
181 | struct device *d; | |
182 | ||
183 | if (!nvmem_np) | |
184 | return NULL; | |
185 | ||
186 | d = bus_find_device(&nvmem_bus_type, NULL, nvmem_np, of_nvmem_match); | |
187 | ||
188 | if (!d) | |
189 | return NULL; | |
190 | ||
191 | return to_nvmem_device(d); | |
192 | } | |
193 | ||
194 | static struct nvmem_cell *nvmem_find_cell(const char *cell_id) | |
195 | { | |
196 | struct nvmem_cell *p; | |
197 | ||
198 | list_for_each_entry(p, &nvmem_cells, node) | |
199 | if (p && !strcmp(p->name, cell_id)) | |
200 | return p; | |
201 | ||
202 | return NULL; | |
203 | } | |
204 | ||
205 | static void nvmem_cell_drop(struct nvmem_cell *cell) | |
206 | { | |
207 | mutex_lock(&nvmem_cells_mutex); | |
208 | list_del(&cell->node); | |
209 | mutex_unlock(&nvmem_cells_mutex); | |
210 | kfree(cell); | |
211 | } | |
212 | ||
213 | static void nvmem_device_remove_all_cells(const struct nvmem_device *nvmem) | |
214 | { | |
215 | struct nvmem_cell *cell; | |
216 | struct list_head *p, *n; | |
217 | ||
218 | list_for_each_safe(p, n, &nvmem_cells) { | |
219 | cell = list_entry(p, struct nvmem_cell, node); | |
220 | if (cell->nvmem == nvmem) | |
221 | nvmem_cell_drop(cell); | |
222 | } | |
223 | } | |
224 | ||
225 | static void nvmem_cell_add(struct nvmem_cell *cell) | |
226 | { | |
227 | mutex_lock(&nvmem_cells_mutex); | |
228 | list_add_tail(&cell->node, &nvmem_cells); | |
229 | mutex_unlock(&nvmem_cells_mutex); | |
230 | } | |
231 | ||
232 | static int nvmem_cell_info_to_nvmem_cell(struct nvmem_device *nvmem, | |
233 | const struct nvmem_cell_info *info, | |
234 | struct nvmem_cell *cell) | |
235 | { | |
236 | cell->nvmem = nvmem; | |
237 | cell->offset = info->offset; | |
238 | cell->bytes = info->bytes; | |
239 | cell->name = info->name; | |
240 | ||
241 | cell->bit_offset = info->bit_offset; | |
242 | cell->nbits = info->nbits; | |
243 | ||
244 | if (cell->nbits) | |
245 | cell->bytes = DIV_ROUND_UP(cell->nbits + cell->bit_offset, | |
246 | BITS_PER_BYTE); | |
247 | ||
248 | if (!IS_ALIGNED(cell->offset, nvmem->stride)) { | |
249 | dev_err(&nvmem->dev, | |
250 | "cell %s unaligned to nvmem stride %d\n", | |
251 | cell->name, nvmem->stride); | |
252 | return -EINVAL; | |
253 | } | |
254 | ||
255 | return 0; | |
256 | } | |
257 | ||
258 | static int nvmem_add_cells(struct nvmem_device *nvmem, | |
259 | const struct nvmem_config *cfg) | |
260 | { | |
261 | struct nvmem_cell **cells; | |
262 | const struct nvmem_cell_info *info = cfg->cells; | |
263 | int i, rval; | |
264 | ||
265 | cells = kcalloc(cfg->ncells, sizeof(*cells), GFP_KERNEL); | |
266 | if (!cells) | |
267 | return -ENOMEM; | |
268 | ||
269 | for (i = 0; i < cfg->ncells; i++) { | |
270 | cells[i] = kzalloc(sizeof(**cells), GFP_KERNEL); | |
271 | if (!cells[i]) { | |
272 | rval = -ENOMEM; | |
273 | goto err; | |
274 | } | |
275 | ||
276 | rval = nvmem_cell_info_to_nvmem_cell(nvmem, &info[i], cells[i]); | |
277 | if (IS_ERR_VALUE(rval)) { | |
278 | kfree(cells[i]); | |
279 | goto err; | |
280 | } | |
281 | ||
282 | nvmem_cell_add(cells[i]); | |
283 | } | |
284 | ||
285 | nvmem->ncells = cfg->ncells; | |
286 | /* remove tmp array */ | |
287 | kfree(cells); | |
288 | ||
289 | return 0; | |
290 | err: | |
291 | while (--i) | |
292 | nvmem_cell_drop(cells[i]); | |
293 | ||
294 | return rval; | |
295 | } | |
296 | ||
297 | /** | |
298 | * nvmem_register() - Register a nvmem device for given nvmem_config. | |
299 | * Also creates an binary entry in /sys/bus/nvmem/devices/dev-name/nvmem | |
300 | * | |
301 | * @config: nvmem device configuration with which nvmem device is created. | |
302 | * | |
303 | * Return: Will be an ERR_PTR() on error or a valid pointer to nvmem_device | |
304 | * on success. | |
305 | */ | |
306 | ||
307 | struct nvmem_device *nvmem_register(const struct nvmem_config *config) | |
308 | { | |
309 | struct nvmem_device *nvmem; | |
310 | struct device_node *np; | |
311 | struct regmap *rm; | |
312 | int rval; | |
313 | ||
314 | if (!config->dev) | |
315 | return ERR_PTR(-EINVAL); | |
316 | ||
317 | rm = dev_get_regmap(config->dev, NULL); | |
318 | if (!rm) { | |
319 | dev_err(config->dev, "Regmap not found\n"); | |
320 | return ERR_PTR(-EINVAL); | |
321 | } | |
322 | ||
323 | nvmem = kzalloc(sizeof(*nvmem), GFP_KERNEL); | |
324 | if (!nvmem) | |
325 | return ERR_PTR(-ENOMEM); | |
326 | ||
327 | rval = ida_simple_get(&nvmem_ida, 0, 0, GFP_KERNEL); | |
328 | if (rval < 0) { | |
329 | kfree(nvmem); | |
330 | return ERR_PTR(rval); | |
331 | } | |
332 | ||
333 | nvmem->id = rval; | |
334 | nvmem->regmap = rm; | |
335 | nvmem->owner = config->owner; | |
336 | nvmem->stride = regmap_get_reg_stride(rm); | |
337 | nvmem->word_size = regmap_get_val_bytes(rm); | |
338 | nvmem->size = regmap_get_max_register(rm) + nvmem->stride; | |
339 | nvmem->dev.type = &nvmem_provider_type; | |
340 | nvmem->dev.bus = &nvmem_bus_type; | |
341 | nvmem->dev.parent = config->dev; | |
342 | np = config->dev->of_node; | |
343 | nvmem->dev.of_node = np; | |
344 | dev_set_name(&nvmem->dev, "%s%d", | |
345 | config->name ? : "nvmem", config->id); | |
346 | ||
347 | nvmem->read_only = of_property_read_bool(np, "read-only") | | |
348 | config->read_only; | |
349 | ||
350 | nvmem->dev.groups = nvmem->read_only ? nvmem_ro_dev_groups : | |
351 | nvmem_rw_dev_groups; | |
352 | ||
353 | device_initialize(&nvmem->dev); | |
354 | ||
355 | dev_dbg(&nvmem->dev, "Registering nvmem device %s\n", config->name); | |
356 | ||
357 | rval = device_add(&nvmem->dev); | |
358 | if (rval) { | |
359 | ida_simple_remove(&nvmem_ida, nvmem->id); | |
360 | kfree(nvmem); | |
361 | return ERR_PTR(rval); | |
362 | } | |
363 | ||
364 | if (config->cells) | |
365 | nvmem_add_cells(nvmem, config); | |
366 | ||
367 | return nvmem; | |
368 | } | |
369 | EXPORT_SYMBOL_GPL(nvmem_register); | |
370 | ||
371 | /** | |
372 | * nvmem_unregister() - Unregister previously registered nvmem device | |
373 | * | |
374 | * @nvmem: Pointer to previously registered nvmem device. | |
375 | * | |
376 | * Return: Will be an negative on error or a zero on success. | |
377 | */ | |
378 | int nvmem_unregister(struct nvmem_device *nvmem) | |
379 | { | |
380 | if (nvmem->users) | |
381 | return -EBUSY; | |
382 | ||
383 | nvmem_device_remove_all_cells(nvmem); | |
384 | device_del(&nvmem->dev); | |
385 | ||
386 | return 0; | |
387 | } | |
388 | EXPORT_SYMBOL_GPL(nvmem_unregister); | |
389 | ||
390 | static int __init nvmem_init(void) | |
391 | { | |
392 | return bus_register(&nvmem_bus_type); | |
393 | } | |
394 | ||
395 | static void __exit nvmem_exit(void) | |
396 | { | |
397 | bus_unregister(&nvmem_bus_type); | |
398 | } | |
399 | ||
400 | subsys_initcall(nvmem_init); | |
401 | module_exit(nvmem_exit); | |
402 | ||
403 | MODULE_AUTHOR("Srinivas Kandagatla <srinivas.kandagatla@linaro.org"); | |
404 | MODULE_AUTHOR("Maxime Ripard <maxime.ripard@free-electrons.com"); | |
405 | MODULE_DESCRIPTION("nvmem Driver Core"); | |
406 | MODULE_LICENSE("GPL v2"); |