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treewide: remove redundant IS_ERR() before error code check
[linux/fpc-iii.git] / drivers / misc / eeprom / at25.c
blobcde9a2fc1325065b054bf89363f7b568e15145c9
1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /*
3 * at25.c -- support most SPI EEPROMs, such as Atmel AT25 models
4 *
5 * Copyright (C) 2006 David Brownell
6 */
7
8 #include <linux/kernel.h>
9 #include <linux/module.h>
10 #include <linux/slab.h>
11 #include <linux/delay.h>
12 #include <linux/device.h>
13 #include <linux/sched.h>
14
15 #include <linux/nvmem-provider.h>
16 #include <linux/spi/spi.h>
17 #include <linux/spi/eeprom.h>
18 #include <linux/property.h>
19
20 /*
21 * NOTE: this is an *EEPROM* driver. The vagaries of product naming
22 * mean that some AT25 products are EEPROMs, and others are FLASH.
23 * Handle FLASH chips with the drivers/mtd/devices/m25p80.c driver,
24 * not this one!
25 */
26
27 struct at25_data {
28 struct spi_device *spi;
29 struct mutex lock;
30 struct spi_eeprom chip;
31 unsigned addrlen;
32 struct nvmem_config nvmem_config;
33 struct nvmem_device *nvmem;
34 };
35
36 #define AT25_WREN 0x06 /* latch the write enable */
37 #define AT25_WRDI 0x04 /* reset the write enable */
38 #define AT25_RDSR 0x05 /* read status register */
39 #define AT25_WRSR 0x01 /* write status register */
40 #define AT25_READ 0x03 /* read byte(s) */
41 #define AT25_WRITE 0x02 /* write byte(s)/sector */
42
43 #define AT25_SR_nRDY 0x01 /* nRDY = write-in-progress */
44 #define AT25_SR_WEN 0x02 /* write enable (latched) */
45 #define AT25_SR_BP0 0x04 /* BP for software writeprotect */
46 #define AT25_SR_BP1 0x08
47 #define AT25_SR_WPEN 0x80 /* writeprotect enable */
48
49 #define AT25_INSTR_BIT3 0x08 /* Additional address bit in instr */
50
51 #define EE_MAXADDRLEN 3 /* 24 bit addresses, up to 2 MBytes */
52
53 /* Specs often allow 5 msec for a page write, sometimes 20 msec;
54 * it's important to recover from write timeouts.
55 */
56 #define EE_TIMEOUT 25
57
58 /*-------------------------------------------------------------------------*/
59
60 #define io_limit PAGE_SIZE /* bytes */
61
62 static int at25_ee_read(void *priv, unsigned int offset,
63 void *val, size_t count)
64 {
65 struct at25_data *at25 = priv;
66 char *buf = val;
67 u8 command[EE_MAXADDRLEN + 1];
68 u8 *cp;
69 ssize_t status;
70 struct spi_transfer t[2];
71 struct spi_message m;
72 u8 instr;
73
74 if (unlikely(offset >= at25->chip.byte_len))
75 return -EINVAL;
76 if ((offset + count) > at25->chip.byte_len)
77 count = at25->chip.byte_len - offset;
78 if (unlikely(!count))
79 return -EINVAL;
80
81 cp = command;
82
83 instr = AT25_READ;
84 if (at25->chip.flags & EE_INSTR_BIT3_IS_ADDR)
85 if (offset >= (1U << (at25->addrlen * 8)))
86 instr |= AT25_INSTR_BIT3;
87 *cp++ = instr;
88
89 /* 8/16/24-bit address is written MSB first */
90 switch (at25->addrlen) {
91 default: /* case 3 */
92 *cp++ = offset >> 16;
93 /* fall through */
94 case 2:
95 *cp++ = offset >> 8;
96 /* fall through */
97 case 1:
98 case 0: /* can't happen: for better codegen */
99 *cp++ = offset >> 0;
100 }
101
102 spi_message_init(&m);
103 memset(t, 0, sizeof(t));
104
105 t[0].tx_buf = command;
106 t[0].len = at25->addrlen + 1;
107 spi_message_add_tail(&t[0], &m);
108
109 t[1].rx_buf = buf;
110 t[1].len = count;
111 spi_message_add_tail(&t[1], &m);
112
113 mutex_lock(&at25->lock);
114
115 /* Read it all at once.
116 *
117 * REVISIT that's potentially a problem with large chips, if
118 * other devices on the bus need to be accessed regularly or
119 * this chip is clocked very slowly
120 */
121 status = spi_sync(at25->spi, &m);
122 dev_dbg(&at25->spi->dev, "read %zu bytes at %d --> %zd\n",
123 count, offset, status);
124
125 mutex_unlock(&at25->lock);
126 return status;
127 }
128
129 static int at25_ee_write(void *priv, unsigned int off, void *val, size_t count)
130 {
131 struct at25_data *at25 = priv;
132 const char *buf = val;
133 int status = 0;
134 unsigned buf_size;
135 u8 *bounce;
136
137 if (unlikely(off >= at25->chip.byte_len))
138 return -EFBIG;
139 if ((off + count) > at25->chip.byte_len)
140 count = at25->chip.byte_len - off;
141 if (unlikely(!count))
142 return -EINVAL;
143
144 /* Temp buffer starts with command and address */
145 buf_size = at25->chip.page_size;
146 if (buf_size > io_limit)
147 buf_size = io_limit;
148 bounce = kmalloc(buf_size + at25->addrlen + 1, GFP_KERNEL);
149 if (!bounce)
150 return -ENOMEM;
151
152 /* For write, rollover is within the page ... so we write at
153 * most one page, then manually roll over to the next page.
154 */
155 mutex_lock(&at25->lock);
156 do {
157 unsigned long timeout, retries;
158 unsigned segment;
159 unsigned offset = (unsigned) off;
160 u8 *cp = bounce;
161 int sr;
162 u8 instr;
163
164 *cp = AT25_WREN;
165 status = spi_write(at25->spi, cp, 1);
166 if (status < 0) {
167 dev_dbg(&at25->spi->dev, "WREN --> %d\n", status);
168 break;
169 }
170
171 instr = AT25_WRITE;
172 if (at25->chip.flags & EE_INSTR_BIT3_IS_ADDR)
173 if (offset >= (1U << (at25->addrlen * 8)))
174 instr |= AT25_INSTR_BIT3;
175 *cp++ = instr;
176
177 /* 8/16/24-bit address is written MSB first */
178 switch (at25->addrlen) {
179 default: /* case 3 */
180 *cp++ = offset >> 16;
181 /* fall through */
182 case 2:
183 *cp++ = offset >> 8;
184 /* fall through */
185 case 1:
186 case 0: /* can't happen: for better codegen */
187 *cp++ = offset >> 0;
188 }
189
190 /* Write as much of a page as we can */
191 segment = buf_size - (offset % buf_size);
192 if (segment > count)
193 segment = count;
194 memcpy(cp, buf, segment);
195 status = spi_write(at25->spi, bounce,
196 segment + at25->addrlen + 1);
197 dev_dbg(&at25->spi->dev, "write %u bytes at %u --> %d\n",
198 segment, offset, status);
199 if (status < 0)
200 break;
201
202 /* REVISIT this should detect (or prevent) failed writes
203 * to readonly sections of the EEPROM...
204 */
205
206 /* Wait for non-busy status */
207 timeout = jiffies + msecs_to_jiffies(EE_TIMEOUT);
208 retries = 0;
209 do {
210
211 sr = spi_w8r8(at25->spi, AT25_RDSR);
212 if (sr < 0 || (sr & AT25_SR_nRDY)) {
213 dev_dbg(&at25->spi->dev,
214 "rdsr --> %d (%02x)\n", sr, sr);
215 /* at HZ=100, this is sloooow */
216 msleep(1);
217 continue;
218 }
219 if (!(sr & AT25_SR_nRDY))
220 break;
221 } while (retries++ < 3 || time_before_eq(jiffies, timeout));
222
223 if ((sr < 0) || (sr & AT25_SR_nRDY)) {
224 dev_err(&at25->spi->dev,
225 "write %u bytes offset %u, timeout after %u msecs\n",
226 segment, offset,
227 jiffies_to_msecs(jiffies -
228 (timeout - EE_TIMEOUT)));
229 status = -ETIMEDOUT;
230 break;
231 }
232
233 off += segment;
234 buf += segment;
235 count -= segment;
236
237 } while (count > 0);
238
239 mutex_unlock(&at25->lock);
240
241 kfree(bounce);
242 return status;
243 }
244
245 /*-------------------------------------------------------------------------*/
246
247 static int at25_fw_to_chip(struct device *dev, struct spi_eeprom *chip)
248 {
249 u32 val;
250
251 memset(chip, 0, sizeof(*chip));
252 strncpy(chip->name, "at25", sizeof(chip->name));
253
254 if (device_property_read_u32(dev, "size", &val) == 0 ||
255 device_property_read_u32(dev, "at25,byte-len", &val) == 0) {
256 chip->byte_len = val;
257 } else {
258 dev_err(dev, "Error: missing \"size\" property\n");
259 return -ENODEV;
260 }
261
262 if (device_property_read_u32(dev, "pagesize", &val) == 0 ||
263 device_property_read_u32(dev, "at25,page-size", &val) == 0) {
264 chip->page_size = (u16)val;
265 } else {
266 dev_err(dev, "Error: missing \"pagesize\" property\n");
267 return -ENODEV;
268 }
269
270 if (device_property_read_u32(dev, "at25,addr-mode", &val) == 0) {
271 chip->flags = (u16)val;
272 } else {
273 if (device_property_read_u32(dev, "address-width", &val)) {
274 dev_err(dev,
275 "Error: missing \"address-width\" property\n");
276 return -ENODEV;
277 }
278 switch (val) {
279 case 9:
280 chip->flags |= EE_INSTR_BIT3_IS_ADDR;
281 /* fall through */
282 case 8:
283 chip->flags |= EE_ADDR1;
284 break;
285 case 16:
286 chip->flags |= EE_ADDR2;
287 break;
288 case 24:
289 chip->flags |= EE_ADDR3;
290 break;
291 default:
292 dev_err(dev,
293 "Error: bad \"address-width\" property: %u\n",
294 val);
295 return -ENODEV;
296 }
297 if (device_property_present(dev, "read-only"))
298 chip->flags |= EE_READONLY;
299 }
300 return 0;
301 }
302
303 static int at25_probe(struct spi_device *spi)
304 {
305 struct at25_data *at25 = NULL;
306 struct spi_eeprom chip;
307 int err;
308 int sr;
309 int addrlen;
310
311 /* Chip description */
312 if (!spi->dev.platform_data) {
313 err = at25_fw_to_chip(&spi->dev, &chip);
314 if (err)
315 return err;
316 } else
317 chip = *(struct spi_eeprom *)spi->dev.platform_data;
318
319 /* For now we only support 8/16/24 bit addressing */
320 if (chip.flags & EE_ADDR1)
321 addrlen = 1;
322 else if (chip.flags & EE_ADDR2)
323 addrlen = 2;
324 else if (chip.flags & EE_ADDR3)
325 addrlen = 3;
326 else {
327 dev_dbg(&spi->dev, "unsupported address type\n");
328 return -EINVAL;
329 }
330
331 /* Ping the chip ... the status register is pretty portable,
332 * unlike probing manufacturer IDs. We do expect that system
333 * firmware didn't write it in the past few milliseconds!
334 */
335 sr = spi_w8r8(spi, AT25_RDSR);
336 if (sr < 0 || sr & AT25_SR_nRDY) {
337 dev_dbg(&spi->dev, "rdsr --> %d (%02x)\n", sr, sr);
338 return -ENXIO;
339 }
340
341 at25 = devm_kzalloc(&spi->dev, sizeof(struct at25_data), GFP_KERNEL);
342 if (!at25)
343 return -ENOMEM;
344
345 mutex_init(&at25->lock);
346 at25->chip = chip;
347 at25->spi = spi;
348 spi_set_drvdata(spi, at25);
349 at25->addrlen = addrlen;
350
351 at25->nvmem_config.name = dev_name(&spi->dev);
352 at25->nvmem_config.dev = &spi->dev;
353 at25->nvmem_config.read_only = chip.flags & EE_READONLY;
354 at25->nvmem_config.root_only = true;
355 at25->nvmem_config.owner = THIS_MODULE;
356 at25->nvmem_config.compat = true;
357 at25->nvmem_config.base_dev = &spi->dev;
358 at25->nvmem_config.reg_read = at25_ee_read;
359 at25->nvmem_config.reg_write = at25_ee_write;
360 at25->nvmem_config.priv = at25;
361 at25->nvmem_config.stride = 4;
362 at25->nvmem_config.word_size = 1;
363 at25->nvmem_config.size = chip.byte_len;
364
365 at25->nvmem = devm_nvmem_register(&spi->dev, &at25->nvmem_config);
366 if (IS_ERR(at25->nvmem))
367 return PTR_ERR(at25->nvmem);
368
369 dev_info(&spi->dev, "%d %s %s eeprom%s, pagesize %u\n",
370 (chip.byte_len < 1024) ? chip.byte_len : (chip.byte_len / 1024),
371 (chip.byte_len < 1024) ? "Byte" : "KByte",
372 at25->chip.name,
373 (chip.flags & EE_READONLY) ? " (readonly)" : "",
374 at25->chip.page_size);
375 return 0;
376 }
377
378 /*-------------------------------------------------------------------------*/
379
380 static const struct of_device_id at25_of_match[] = {
381 { .compatible = "atmel,at25", },
382 { }
383 };
384 MODULE_DEVICE_TABLE(of, at25_of_match);
385
386 static struct spi_driver at25_driver = {
387 .driver = {
388 .name = "at25",
389 .of_match_table = at25_of_match,
390 },
391 .probe = at25_probe,
392 };
393
394 module_spi_driver(at25_driver);
395
396 MODULE_DESCRIPTION("Driver for most SPI EEPROMs");
397 MODULE_AUTHOR("David Brownell");
398 MODULE_LICENSE("GPL");
399 MODULE_ALIAS("spi:at25");
Linux with added FPC-III support