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3b51f47b AS |
1 | // SPDX-License-Identifier: GPL-2.0+ |
2 | ||
3 | /* | |
4 | * EEPROM driver for RAVE SP | |
5 | * | |
6 | * Copyright (C) 2018 Zodiac Inflight Innovations | |
7 | * | |
8 | */ | |
9 | #include <linux/kernel.h> | |
10 | #include <linux/mfd/rave-sp.h> | |
11 | #include <linux/module.h> | |
12 | #include <linux/nvmem-provider.h> | |
13 | #include <linux/of_device.h> | |
14 | #include <linux/platform_device.h> | |
15 | #include <linux/sizes.h> | |
16 | ||
17 | /** | |
18 | * enum rave_sp_eeprom_access_type - Supported types of EEPROM access | |
19 | * | |
20 | * @RAVE_SP_EEPROM_WRITE: EEPROM write | |
21 | * @RAVE_SP_EEPROM_READ: EEPROM read | |
22 | */ | |
23 | enum rave_sp_eeprom_access_type { | |
24 | RAVE_SP_EEPROM_WRITE = 0, | |
25 | RAVE_SP_EEPROM_READ = 1, | |
26 | }; | |
27 | ||
28 | /** | |
29 | * enum rave_sp_eeprom_header_size - EEPROM command header sizes | |
30 | * | |
31 | * @RAVE_SP_EEPROM_HEADER_SMALL: EEPROM header size for "small" devices (< 8K) | |
32 | * @RAVE_SP_EEPROM_HEADER_BIG: EEPROM header size for "big" devices (> 8K) | |
33 | */ | |
34 | enum rave_sp_eeprom_header_size { | |
35 | RAVE_SP_EEPROM_HEADER_SMALL = 4U, | |
36 | RAVE_SP_EEPROM_HEADER_BIG = 5U, | |
37 | }; | |
38 | ||
39 | #define RAVE_SP_EEPROM_PAGE_SIZE 32U | |
40 | ||
41 | /** | |
42 | * struct rave_sp_eeprom_page - RAVE SP EEPROM page | |
43 | * | |
44 | * @type: Access type (see enum rave_sp_eeprom_access_type) | |
45 | * @success: Success flag (Success = 1, Failure = 0) | |
46 | * @data: Read data | |
47 | ||
48 | * Note this structure corresponds to RSP_*_EEPROM payload from RAVE | |
49 | * SP ICD | |
50 | */ | |
51 | struct rave_sp_eeprom_page { | |
52 | u8 type; | |
53 | u8 success; | |
54 | u8 data[RAVE_SP_EEPROM_PAGE_SIZE]; | |
55 | } __packed; | |
56 | ||
57 | /** | |
58 | * struct rave_sp_eeprom - RAVE SP EEPROM device | |
59 | * | |
60 | * @sp: Pointer to parent RAVE SP device | |
61 | * @mutex: Lock protecting access to EEPROM | |
62 | * @address: EEPROM device address | |
63 | * @header_size: Size of EEPROM command header for this device | |
64 | * @dev: Pointer to corresponding struct device used for logging | |
65 | */ | |
66 | struct rave_sp_eeprom { | |
67 | struct rave_sp *sp; | |
68 | struct mutex mutex; | |
69 | u8 address; | |
70 | unsigned int header_size; | |
71 | struct device *dev; | |
72 | }; | |
73 | ||
74 | /** | |
75 | * rave_sp_eeprom_io - Low-level part of EEPROM page access | |
76 | * | |
77 | * @eeprom: EEPROM device to write to | |
78 | * @type: EEPROM access type (read or write) | |
79 | * @idx: number of the EEPROM page | |
80 | * @page: Data to write or buffer to store result (via page->data) | |
81 | * | |
82 | * This function does all of the low-level work required to perform a | |
83 | * EEPROM access. This includes formatting correct command payload, | |
84 | * sending it and checking received results. | |
85 | * | |
86 | * Returns zero in case of success or negative error code in | |
87 | * case of failure. | |
88 | */ | |
89 | static int rave_sp_eeprom_io(struct rave_sp_eeprom *eeprom, | |
90 | enum rave_sp_eeprom_access_type type, | |
91 | u16 idx, | |
92 | struct rave_sp_eeprom_page *page) | |
93 | { | |
94 | const bool is_write = type == RAVE_SP_EEPROM_WRITE; | |
95 | const unsigned int data_size = is_write ? sizeof(page->data) : 0; | |
96 | const unsigned int cmd_size = eeprom->header_size + data_size; | |
97 | const unsigned int rsp_size = | |
98 | is_write ? sizeof(*page) - sizeof(page->data) : sizeof(*page); | |
99 | unsigned int offset = 0; | |
100 | u8 cmd[cmd_size]; | |
101 | int ret; | |
102 | ||
103 | cmd[offset++] = eeprom->address; | |
104 | cmd[offset++] = 0; | |
105 | cmd[offset++] = type; | |
106 | cmd[offset++] = idx; | |
107 | ||
108 | /* | |
109 | * If there's still room in this command's header it means we | |
110 | * are talkin to EEPROM that uses 16-bit page numbers and we | |
111 | * have to specify index's MSB in payload as well. | |
112 | */ | |
113 | if (offset < eeprom->header_size) | |
114 | cmd[offset++] = idx >> 8; | |
115 | /* | |
116 | * Copy our data to write to command buffer first. In case of | |
117 | * a read data_size should be zero and memcpy would become a | |
118 | * no-op | |
119 | */ | |
120 | memcpy(&cmd[offset], page->data, data_size); | |
121 | ||
122 | ret = rave_sp_exec(eeprom->sp, cmd, cmd_size, page, rsp_size); | |
123 | if (ret) | |
124 | return ret; | |
125 | ||
126 | if (page->type != type) | |
127 | return -EPROTO; | |
128 | ||
129 | if (!page->success) | |
130 | return -EIO; | |
131 | ||
132 | return 0; | |
133 | } | |
134 | ||
135 | /** | |
136 | * rave_sp_eeprom_page_access - Access single EEPROM page | |
137 | * | |
138 | * @eeprom: EEPROM device to access | |
139 | * @type: Access type to perform (read or write) | |
140 | * @offset: Offset within EEPROM to access | |
141 | * @data: Data buffer | |
142 | * @data_len: Size of the data buffer | |
143 | * | |
144 | * This function performs a generic access to a single page or a | |
145 | * portion thereof. Requested access MUST NOT cross the EEPROM page | |
146 | * boundary. | |
147 | * | |
148 | * Returns zero in case of success or negative error code in | |
149 | * case of failure. | |
150 | */ | |
151 | static int | |
152 | rave_sp_eeprom_page_access(struct rave_sp_eeprom *eeprom, | |
153 | enum rave_sp_eeprom_access_type type, | |
154 | unsigned int offset, u8 *data, | |
155 | size_t data_len) | |
156 | { | |
157 | const unsigned int page_offset = offset % RAVE_SP_EEPROM_PAGE_SIZE; | |
158 | const unsigned int page_nr = offset / RAVE_SP_EEPROM_PAGE_SIZE; | |
159 | struct rave_sp_eeprom_page page; | |
160 | int ret; | |
161 | ||
162 | /* | |
163 | * This function will not work if data access we've been asked | |
164 | * to do is crossing EEPROM page boundary. Normally this | |
165 | * should never happen and getting here would indicate a bug | |
166 | * in the code. | |
167 | */ | |
168 | if (WARN_ON(data_len > sizeof(page.data) - page_offset)) | |
169 | return -EINVAL; | |
170 | ||
171 | if (type == RAVE_SP_EEPROM_WRITE) { | |
172 | /* | |
173 | * If doing a partial write we need to do a read first | |
174 | * to fill the rest of the page with correct data. | |
175 | */ | |
176 | if (data_len < RAVE_SP_EEPROM_PAGE_SIZE) { | |
177 | ret = rave_sp_eeprom_io(eeprom, RAVE_SP_EEPROM_READ, | |
178 | page_nr, &page); | |
179 | if (ret) | |
180 | return ret; | |
181 | } | |
182 | ||
183 | memcpy(&page.data[page_offset], data, data_len); | |
184 | } | |
185 | ||
186 | ret = rave_sp_eeprom_io(eeprom, type, page_nr, &page); | |
187 | if (ret) | |
188 | return ret; | |
189 | ||
190 | /* | |
191 | * Since we receive the result of the read via 'page.data' | |
192 | * buffer we need to copy that to 'data' | |
193 | */ | |
194 | if (type == RAVE_SP_EEPROM_READ) | |
195 | memcpy(data, &page.data[page_offset], data_len); | |
196 | ||
197 | return 0; | |
198 | } | |
199 | ||
200 | /** | |
201 | * rave_sp_eeprom_access - Access EEPROM data | |
202 | * | |
203 | * @eeprom: EEPROM device to access | |
204 | * @type: Access type to perform (read or write) | |
205 | * @offset: Offset within EEPROM to access | |
206 | * @data: Data buffer | |
207 | * @data_len: Size of the data buffer | |
208 | * | |
209 | * This function performs a generic access (either read or write) at | |
210 | * arbitrary offset (not necessary page aligned) of arbitrary length | |
211 | * (is not constrained by EEPROM page size). | |
212 | * | |
213 | * Returns zero in case of success or negative error code in case of | |
214 | * failure. | |
215 | */ | |
216 | static int rave_sp_eeprom_access(struct rave_sp_eeprom *eeprom, | |
217 | enum rave_sp_eeprom_access_type type, | |
218 | unsigned int offset, u8 *data, | |
219 | unsigned int data_len) | |
220 | { | |
221 | unsigned int residue; | |
222 | unsigned int chunk; | |
223 | unsigned int head; | |
224 | int ret; | |
225 | ||
226 | mutex_lock(&eeprom->mutex); | |
227 | ||
228 | head = offset % RAVE_SP_EEPROM_PAGE_SIZE; | |
229 | residue = data_len; | |
230 | ||
231 | do { | |
232 | /* | |
233 | * First iteration, if we are doing an access that is | |
234 | * not 32-byte aligned, we need to access only data up | |
235 | * to a page boundary to avoid corssing it in | |
236 | * rave_sp_eeprom_page_access() | |
237 | */ | |
238 | if (unlikely(head)) { | |
239 | chunk = RAVE_SP_EEPROM_PAGE_SIZE - head; | |
240 | /* | |
241 | * This can only happen once per | |
242 | * rave_sp_eeprom_access() call, so we set | |
243 | * head to zero to process all the other | |
244 | * iterations normally. | |
245 | */ | |
246 | head = 0; | |
247 | } else { | |
248 | chunk = RAVE_SP_EEPROM_PAGE_SIZE; | |
249 | } | |
250 | ||
251 | /* | |
252 | * We should never read more that 'residue' bytes | |
253 | */ | |
254 | chunk = min(chunk, residue); | |
255 | ret = rave_sp_eeprom_page_access(eeprom, type, offset, | |
256 | data, chunk); | |
257 | if (ret) | |
258 | goto out; | |
259 | ||
260 | residue -= chunk; | |
261 | offset += chunk; | |
262 | data += chunk; | |
263 | } while (residue); | |
264 | out: | |
265 | mutex_unlock(&eeprom->mutex); | |
266 | return ret; | |
267 | } | |
268 | ||
269 | static int rave_sp_eeprom_reg_read(void *eeprom, unsigned int offset, | |
270 | void *val, size_t bytes) | |
271 | { | |
272 | return rave_sp_eeprom_access(eeprom, RAVE_SP_EEPROM_READ, | |
273 | offset, val, bytes); | |
274 | } | |
275 | ||
276 | static int rave_sp_eeprom_reg_write(void *eeprom, unsigned int offset, | |
277 | void *val, size_t bytes) | |
278 | { | |
279 | return rave_sp_eeprom_access(eeprom, RAVE_SP_EEPROM_WRITE, | |
280 | offset, val, bytes); | |
281 | } | |
282 | ||
283 | static int rave_sp_eeprom_probe(struct platform_device *pdev) | |
284 | { | |
285 | struct device *dev = &pdev->dev; | |
286 | struct rave_sp *sp = dev_get_drvdata(dev->parent); | |
287 | struct device_node *np = dev->of_node; | |
288 | struct nvmem_config config = { 0 }; | |
289 | struct rave_sp_eeprom *eeprom; | |
290 | struct nvmem_device *nvmem; | |
291 | u32 reg[2], size; | |
292 | ||
293 | if (of_property_read_u32_array(np, "reg", reg, ARRAY_SIZE(reg))) { | |
294 | dev_err(dev, "Failed to parse \"reg\" property\n"); | |
295 | return -EINVAL; | |
296 | } | |
297 | ||
298 | size = reg[1]; | |
299 | /* | |
300 | * Per ICD, we have no more than 2 bytes to specify EEPROM | |
301 | * page. | |
302 | */ | |
303 | if (size > U16_MAX * RAVE_SP_EEPROM_PAGE_SIZE) { | |
304 | dev_err(dev, "Specified size is too big\n"); | |
305 | return -EINVAL; | |
306 | } | |
307 | ||
308 | eeprom = devm_kzalloc(dev, sizeof(*eeprom), GFP_KERNEL); | |
309 | if (!eeprom) | |
310 | return -ENOMEM; | |
311 | ||
312 | eeprom->address = reg[0]; | |
313 | eeprom->sp = sp; | |
314 | eeprom->dev = dev; | |
315 | ||
316 | if (size > SZ_8K) | |
317 | eeprom->header_size = RAVE_SP_EEPROM_HEADER_BIG; | |
318 | else | |
319 | eeprom->header_size = RAVE_SP_EEPROM_HEADER_SMALL; | |
320 | ||
321 | mutex_init(&eeprom->mutex); | |
322 | ||
323 | config.id = -1; | |
324 | of_property_read_string(np, "zii,eeprom-name", &config.name); | |
325 | config.priv = eeprom; | |
326 | config.dev = dev; | |
327 | config.size = size; | |
328 | config.reg_read = rave_sp_eeprom_reg_read; | |
329 | config.reg_write = rave_sp_eeprom_reg_write; | |
330 | config.word_size = 1; | |
331 | config.stride = 1; | |
332 | ||
333 | nvmem = devm_nvmem_register(dev, &config); | |
334 | ||
335 | return PTR_ERR_OR_ZERO(nvmem); | |
336 | } | |
337 | ||
338 | static const struct of_device_id rave_sp_eeprom_of_match[] = { | |
339 | { .compatible = "zii,rave-sp-eeprom" }, | |
340 | {} | |
341 | }; | |
342 | MODULE_DEVICE_TABLE(of, rave_sp_eeprom_of_match); | |
343 | ||
344 | static struct platform_driver rave_sp_eeprom_driver = { | |
345 | .probe = rave_sp_eeprom_probe, | |
346 | .driver = { | |
347 | .name = KBUILD_MODNAME, | |
348 | .of_match_table = rave_sp_eeprom_of_match, | |
349 | }, | |
350 | }; | |
351 | module_platform_driver(rave_sp_eeprom_driver); | |
352 | ||
353 | MODULE_LICENSE("GPL"); | |
354 | MODULE_AUTHOR("Andrey Vostrikov <andrey.vostrikov@cogentembedded.com>"); | |
355 | MODULE_AUTHOR("Nikita Yushchenko <nikita.yoush@cogentembedded.com>"); | |
356 | MODULE_AUTHOR("Andrey Smirnov <andrew.smirnov@gmail.com>"); | |
357 | MODULE_DESCRIPTION("RAVE SP EEPROM driver"); |