blob: b34cb5f79eea94ce1c23a82f2f33205a93451313 [file] [log] [blame]
David Brownellb587b132007-02-12 00:52:48 -08001/*
2 * at25.c -- support most SPI EEPROMs, such as Atmel AT25 models
3 *
4 * Copyright (C) 2006 David Brownell
5 *
6 * This program is free software; you can redistribute it and/or modify
7 * it under the terms of the GNU General Public License as published by
8 * the Free Software Foundation; either version 2 of the License, or
9 * (at your option) any later version.
10 */
11
12#include <linux/kernel.h>
13#include <linux/init.h>
14#include <linux/module.h>
15#include <linux/slab.h>
16#include <linux/delay.h>
17#include <linux/device.h>
18#include <linux/sched.h>
19
20#include <linux/spi/spi.h>
21#include <linux/spi/eeprom.h>
22
23
David Brownell3f86f142007-12-04 23:45:10 -080024/*
25 * NOTE: this is an *EEPROM* driver. The vagaries of product naming
26 * mean that some AT25 products are EEPROMs, and others are FLASH.
27 * Handle FLASH chips with the drivers/mtd/devices/m25p80.c driver,
28 * not this one!
29 */
30
David Brownellb587b132007-02-12 00:52:48 -080031struct at25_data {
32 struct spi_device *spi;
David Brownell14dd1ff2009-04-02 16:56:58 -070033 struct memory_accessor mem;
David Brownellb587b132007-02-12 00:52:48 -080034 struct mutex lock;
35 struct spi_eeprom chip;
36 struct bin_attribute bin;
37 unsigned addrlen;
38};
39
40#define AT25_WREN 0x06 /* latch the write enable */
41#define AT25_WRDI 0x04 /* reset the write enable */
42#define AT25_RDSR 0x05 /* read status register */
43#define AT25_WRSR 0x01 /* write status register */
44#define AT25_READ 0x03 /* read byte(s) */
45#define AT25_WRITE 0x02 /* write byte(s)/sector */
46
47#define AT25_SR_nRDY 0x01 /* nRDY = write-in-progress */
48#define AT25_SR_WEN 0x02 /* write enable (latched) */
49#define AT25_SR_BP0 0x04 /* BP for software writeprotect */
50#define AT25_SR_BP1 0x08
51#define AT25_SR_WPEN 0x80 /* writeprotect enable */
52
53
54#define EE_MAXADDRLEN 3 /* 24 bit addresses, up to 2 MBytes */
55
56/* Specs often allow 5 msec for a page write, sometimes 20 msec;
57 * it's important to recover from write timeouts.
58 */
59#define EE_TIMEOUT 25
60
61/*-------------------------------------------------------------------------*/
62
63#define io_limit PAGE_SIZE /* bytes */
64
65static ssize_t
66at25_ee_read(
67 struct at25_data *at25,
68 char *buf,
69 unsigned offset,
70 size_t count
71)
72{
73 u8 command[EE_MAXADDRLEN + 1];
74 u8 *cp;
75 ssize_t status;
76 struct spi_transfer t[2];
77 struct spi_message m;
78
David Brownell14dd1ff2009-04-02 16:56:58 -070079 if (unlikely(offset >= at25->bin.size))
80 return 0;
81 if ((offset + count) > at25->bin.size)
82 count = at25->bin.size - offset;
83 if (unlikely(!count))
84 return count;
85
David Brownellb587b132007-02-12 00:52:48 -080086 cp = command;
87 *cp++ = AT25_READ;
88
89 /* 8/16/24-bit address is written MSB first */
90 switch (at25->addrlen) {
91 default: /* case 3 */
92 *cp++ = offset >> 16;
93 case 2:
94 *cp++ = offset >> 8;
95 case 1:
96 case 0: /* can't happen: for better codegen */
97 *cp++ = offset >> 0;
98 }
99
100 spi_message_init(&m);
101 memset(t, 0, sizeof t);
102
103 t[0].tx_buf = command;
104 t[0].len = at25->addrlen + 1;
105 spi_message_add_tail(&t[0], &m);
106
107 t[1].rx_buf = buf;
108 t[1].len = count;
109 spi_message_add_tail(&t[1], &m);
110
111 mutex_lock(&at25->lock);
112
113 /* Read it all at once.
114 *
115 * REVISIT that's potentially a problem with large chips, if
116 * other devices on the bus need to be accessed regularly or
117 * this chip is clocked very slowly
118 */
119 status = spi_sync(at25->spi, &m);
120 dev_dbg(&at25->spi->dev,
121 "read %Zd bytes at %d --> %d\n",
122 count, offset, (int) status);
123
124 mutex_unlock(&at25->lock);
125 return status ? status : count;
126}
127
128static ssize_t
Zhang Rui91a69022007-06-09 13:57:22 +0800129at25_bin_read(struct kobject *kobj, struct bin_attribute *bin_attr,
130 char *buf, loff_t off, size_t count)
David Brownellb587b132007-02-12 00:52:48 -0800131{
132 struct device *dev;
133 struct at25_data *at25;
134
135 dev = container_of(kobj, struct device, kobj);
136 at25 = dev_get_drvdata(dev);
137
David Brownellb587b132007-02-12 00:52:48 -0800138 return at25_ee_read(at25, buf, off, count);
139}
140
141
142static ssize_t
Geert Uytterhoeven4cafbd02009-04-13 14:40:07 -0700143at25_ee_write(struct at25_data *at25, const char *buf, loff_t off,
144 size_t count)
David Brownellb587b132007-02-12 00:52:48 -0800145{
146 ssize_t status = 0;
147 unsigned written = 0;
148 unsigned buf_size;
149 u8 *bounce;
150
David Brownell14dd1ff2009-04-02 16:56:58 -0700151 if (unlikely(off >= at25->bin.size))
152 return -EFBIG;
153 if ((off + count) > at25->bin.size)
154 count = at25->bin.size - off;
155 if (unlikely(!count))
156 return count;
157
David Brownellb587b132007-02-12 00:52:48 -0800158 /* Temp buffer starts with command and address */
159 buf_size = at25->chip.page_size;
160 if (buf_size > io_limit)
161 buf_size = io_limit;
162 bounce = kmalloc(buf_size + at25->addrlen + 1, GFP_KERNEL);
163 if (!bounce)
164 return -ENOMEM;
165
166 /* For write, rollover is within the page ... so we write at
167 * most one page, then manually roll over to the next page.
168 */
169 bounce[0] = AT25_WRITE;
170 mutex_lock(&at25->lock);
171 do {
172 unsigned long timeout, retries;
173 unsigned segment;
174 unsigned offset = (unsigned) off;
175 u8 *cp = bounce + 1;
176
177 *cp = AT25_WREN;
178 status = spi_write(at25->spi, cp, 1);
179 if (status < 0) {
180 dev_dbg(&at25->spi->dev, "WREN --> %d\n",
181 (int) status);
182 break;
183 }
184
185 /* 8/16/24-bit address is written MSB first */
186 switch (at25->addrlen) {
187 default: /* case 3 */
188 *cp++ = offset >> 16;
189 case 2:
190 *cp++ = offset >> 8;
191 case 1:
192 case 0: /* can't happen: for better codegen */
193 *cp++ = offset >> 0;
194 }
195
196 /* Write as much of a page as we can */
197 segment = buf_size - (offset % buf_size);
198 if (segment > count)
199 segment = count;
200 memcpy(cp, buf, segment);
201 status = spi_write(at25->spi, bounce,
202 segment + at25->addrlen + 1);
203 dev_dbg(&at25->spi->dev,
204 "write %u bytes at %u --> %d\n",
205 segment, offset, (int) status);
206 if (status < 0)
207 break;
208
209 /* REVISIT this should detect (or prevent) failed writes
210 * to readonly sections of the EEPROM...
211 */
212
213 /* Wait for non-busy status */
214 timeout = jiffies + msecs_to_jiffies(EE_TIMEOUT);
215 retries = 0;
216 do {
217 int sr;
218
219 sr = spi_w8r8(at25->spi, AT25_RDSR);
220 if (sr < 0 || (sr & AT25_SR_nRDY)) {
221 dev_dbg(&at25->spi->dev,
222 "rdsr --> %d (%02x)\n", sr, sr);
223 /* at HZ=100, this is sloooow */
224 msleep(1);
225 continue;
226 }
227 if (!(sr & AT25_SR_nRDY))
228 break;
229 } while (retries++ < 3 || time_before_eq(jiffies, timeout));
230
231 if (time_after(jiffies, timeout)) {
232 dev_err(&at25->spi->dev,
233 "write %d bytes offset %d, "
234 "timeout after %u msecs\n",
235 segment, offset,
236 jiffies_to_msecs(jiffies -
237 (timeout - EE_TIMEOUT)));
238 status = -ETIMEDOUT;
239 break;
240 }
241
242 off += segment;
243 buf += segment;
244 count -= segment;
245 written += segment;
246
247 } while (count > 0);
248
249 mutex_unlock(&at25->lock);
250
251 kfree(bounce);
252 return written ? written : status;
253}
254
255static ssize_t
Zhang Rui91a69022007-06-09 13:57:22 +0800256at25_bin_write(struct kobject *kobj, struct bin_attribute *bin_attr,
257 char *buf, loff_t off, size_t count)
David Brownellb587b132007-02-12 00:52:48 -0800258{
259 struct device *dev;
260 struct at25_data *at25;
261
262 dev = container_of(kobj, struct device, kobj);
263 at25 = dev_get_drvdata(dev);
264
David Brownellb587b132007-02-12 00:52:48 -0800265 return at25_ee_write(at25, buf, off, count);
266}
267
268/*-------------------------------------------------------------------------*/
269
David Brownell14dd1ff2009-04-02 16:56:58 -0700270/* Let in-kernel code access the eeprom data. */
271
272static ssize_t at25_mem_read(struct memory_accessor *mem, char *buf,
273 off_t offset, size_t count)
274{
275 struct at25_data *at25 = container_of(mem, struct at25_data, mem);
276
277 return at25_ee_read(at25, buf, offset, count);
278}
279
Geert Uytterhoeven4cafbd02009-04-13 14:40:07 -0700280static ssize_t at25_mem_write(struct memory_accessor *mem, const char *buf,
David Brownell14dd1ff2009-04-02 16:56:58 -0700281 off_t offset, size_t count)
282{
283 struct at25_data *at25 = container_of(mem, struct at25_data, mem);
284
285 return at25_ee_write(at25, buf, offset, count);
286}
287
288/*-------------------------------------------------------------------------*/
289
David Brownellb587b132007-02-12 00:52:48 -0800290static int at25_probe(struct spi_device *spi)
291{
292 struct at25_data *at25 = NULL;
293 const struct spi_eeprom *chip;
294 int err;
295 int sr;
296 int addrlen;
297
298 /* Chip description */
299 chip = spi->dev.platform_data;
300 if (!chip) {
301 dev_dbg(&spi->dev, "no chip description\n");
302 err = -ENODEV;
303 goto fail;
304 }
305
306 /* For now we only support 8/16/24 bit addressing */
307 if (chip->flags & EE_ADDR1)
308 addrlen = 1;
309 else if (chip->flags & EE_ADDR2)
310 addrlen = 2;
311 else if (chip->flags & EE_ADDR3)
312 addrlen = 3;
313 else {
314 dev_dbg(&spi->dev, "unsupported address type\n");
315 err = -EINVAL;
316 goto fail;
317 }
318
319 /* Ping the chip ... the status register is pretty portable,
320 * unlike probing manufacturer IDs. We do expect that system
321 * firmware didn't write it in the past few milliseconds!
322 */
323 sr = spi_w8r8(spi, AT25_RDSR);
324 if (sr < 0 || sr & AT25_SR_nRDY) {
Atsushi Nemotoc6ca97d2007-03-16 13:38:20 -0800325 dev_dbg(&spi->dev, "rdsr --> %d (%02x)\n", sr, sr);
David Brownellb587b132007-02-12 00:52:48 -0800326 err = -ENXIO;
327 goto fail;
328 }
329
330 if (!(at25 = kzalloc(sizeof *at25, GFP_KERNEL))) {
331 err = -ENOMEM;
332 goto fail;
333 }
334
335 mutex_init(&at25->lock);
336 at25->chip = *chip;
337 at25->spi = spi_dev_get(spi);
338 dev_set_drvdata(&spi->dev, at25);
339 at25->addrlen = addrlen;
340
341 /* Export the EEPROM bytes through sysfs, since that's convenient.
David Brownell14dd1ff2009-04-02 16:56:58 -0700342 * And maybe to other kernel code; it might hold a board's Ethernet
343 * address, or board-specific calibration data generated on the
344 * manufacturing floor.
345 *
David Brownellb587b132007-02-12 00:52:48 -0800346 * Default to root-only access to the data; EEPROMs often hold data
347 * that's sensitive for read and/or write, like ethernet addresses,
348 * security codes, board-specific manufacturing calibrations, etc.
349 */
350 at25->bin.attr.name = "eeprom";
351 at25->bin.attr.mode = S_IRUSR;
David Brownellb587b132007-02-12 00:52:48 -0800352 at25->bin.read = at25_bin_read;
David Brownell14dd1ff2009-04-02 16:56:58 -0700353 at25->mem.read = at25_mem_read;
David Brownellb587b132007-02-12 00:52:48 -0800354
355 at25->bin.size = at25->chip.byte_len;
356 if (!(chip->flags & EE_READONLY)) {
357 at25->bin.write = at25_bin_write;
358 at25->bin.attr.mode |= S_IWUSR;
David Brownell14dd1ff2009-04-02 16:56:58 -0700359 at25->mem.write = at25_mem_write;
David Brownellb587b132007-02-12 00:52:48 -0800360 }
361
362 err = sysfs_create_bin_file(&spi->dev.kobj, &at25->bin);
363 if (err)
364 goto fail;
365
David Brownell14dd1ff2009-04-02 16:56:58 -0700366 if (chip->setup)
367 chip->setup(&at25->mem, chip->context);
368
David Brownellb587b132007-02-12 00:52:48 -0800369 dev_info(&spi->dev, "%Zd %s %s eeprom%s, pagesize %u\n",
370 (at25->bin.size < 1024)
371 ? at25->bin.size
372 : (at25->bin.size / 1024),
373 (at25->bin.size < 1024) ? "Byte" : "KByte",
374 at25->chip.name,
375 (chip->flags & EE_READONLY) ? " (readonly)" : "",
376 at25->chip.page_size);
377 return 0;
378fail:
379 dev_dbg(&spi->dev, "probe err %d\n", err);
380 kfree(at25);
381 return err;
382}
383
384static int __devexit at25_remove(struct spi_device *spi)
385{
386 struct at25_data *at25;
387
388 at25 = dev_get_drvdata(&spi->dev);
389 sysfs_remove_bin_file(&spi->dev.kobj, &at25->bin);
390 kfree(at25);
391 return 0;
392}
393
394/*-------------------------------------------------------------------------*/
395
396static struct spi_driver at25_driver = {
397 .driver = {
398 .name = "at25",
399 .owner = THIS_MODULE,
400 },
401 .probe = at25_probe,
402 .remove = __devexit_p(at25_remove),
403};
404
405static int __init at25_init(void)
406{
407 return spi_register_driver(&at25_driver);
408}
409module_init(at25_init);
410
411static void __exit at25_exit(void)
412{
413 spi_unregister_driver(&at25_driver);
414}
415module_exit(at25_exit);
416
417MODULE_DESCRIPTION("Driver for most SPI EEPROMs");
418MODULE_AUTHOR("David Brownell");
419MODULE_LICENSE("GPL");
420