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1/*
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/module.h>
14#include <linux/slab.h>
15#include <linux/delay.h>
16#include <linux/device.h>
17#include <linux/sched.h>
18
19#include <linux/nvmem-provider.h>
20#include <linux/regmap.h>
21#include <linux/spi/spi.h>
22#include <linux/spi/eeprom.h>
23#include <linux/property.h>
24
25/*
26 * NOTE: this is an *EEPROM* driver. The vagaries of product naming
27 * mean that some AT25 products are EEPROMs, and others are FLASH.
28 * Handle FLASH chips with the drivers/mtd/devices/m25p80.c driver,
29 * not this one!
30 */
31
32struct at25_data {
33 struct spi_device *spi;
34 struct mutex lock;
35 struct spi_eeprom chip;
36 unsigned addrlen;
37 struct regmap_config regmap_config;
38 struct nvmem_config nvmem_config;
39 struct nvmem_device *nvmem;
40};
41
42#define AT25_WREN 0x06 /* latch the write enable */
43#define AT25_WRDI 0x04 /* reset the write enable */
44#define AT25_RDSR 0x05 /* read status register */
45#define AT25_WRSR 0x01 /* write status register */
46#define AT25_READ 0x03 /* read byte(s) */
47#define AT25_WRITE 0x02 /* write byte(s)/sector */
48
49#define AT25_SR_nRDY 0x01 /* nRDY = write-in-progress */
50#define AT25_SR_WEN 0x02 /* write enable (latched) */
51#define AT25_SR_BP0 0x04 /* BP for software writeprotect */
52#define AT25_SR_BP1 0x08
53#define AT25_SR_WPEN 0x80 /* writeprotect enable */
54
55#define AT25_INSTR_BIT3 0x08 /* Additional address bit in instr */
56
57#define EE_MAXADDRLEN 3 /* 24 bit addresses, up to 2 MBytes */
58
59/* Specs often allow 5 msec for a page write, sometimes 20 msec;
60 * it's important to recover from write timeouts.
61 */
62#define EE_TIMEOUT 25
63
64/*-------------------------------------------------------------------------*/
65
66#define io_limit PAGE_SIZE /* bytes */
67
68static ssize_t
69at25_ee_read(
70 struct at25_data *at25,
71 char *buf,
72 unsigned offset,
73 size_t count
74)
75{
76 u8 command[EE_MAXADDRLEN + 1];
77 u8 *cp;
78 ssize_t status;
79 struct spi_transfer t[2];
80 struct spi_message m;
81 u8 instr;
82
83 if (unlikely(offset >= at25->chip.byte_len))
84 return 0;
85 if ((offset + count) > at25->chip.byte_len)
86 count = at25->chip.byte_len - offset;
87 if (unlikely(!count))
88 return count;
89
90 cp = command;
91
92 instr = AT25_READ;
93 if (at25->chip.flags & EE_INSTR_BIT3_IS_ADDR)
94 if (offset >= (1U << (at25->addrlen * 8)))
95 instr |= AT25_INSTR_BIT3;
96 *cp++ = instr;
97
98 /* 8/16/24-bit address is written MSB first */
99 switch (at25->addrlen) {
100 default: /* case 3 */
101 *cp++ = offset >> 16;
102 case 2:
103 *cp++ = offset >> 8;
104 case 1:
105 case 0: /* can't happen: for better codegen */
106 *cp++ = offset >> 0;
107 }
108
109 spi_message_init(&m);
110 memset(t, 0, sizeof t);
111
112 t[0].tx_buf = command;
113 t[0].len = at25->addrlen + 1;
114 spi_message_add_tail(&t[0], &m);
115
116 t[1].rx_buf = buf;
117 t[1].len = count;
118 spi_message_add_tail(&t[1], &m);
119
120 mutex_lock(&at25->lock);
121
122 /* Read it all at once.
123 *
124 * REVISIT that's potentially a problem with large chips, if
125 * other devices on the bus need to be accessed regularly or
126 * this chip is clocked very slowly
127 */
128 status = spi_sync(at25->spi, &m);
129 dev_dbg(&at25->spi->dev,
130 "read %Zd bytes at %d --> %d\n",
131 count, offset, (int) status);
132
133 mutex_unlock(&at25->lock);
134 return status ? status : count;
135}
136
137static int at25_regmap_read(void *context, const void *reg, size_t reg_size,
138 void *val, size_t val_size)
139{
140 struct at25_data *at25 = context;
141 off_t offset = *(u32 *)reg;
142 int err;
143
144 err = at25_ee_read(at25, val, offset, val_size);
145 if (err)
146 return err;
147 return 0;
148}
149
150static ssize_t
151at25_ee_write(struct at25_data *at25, const char *buf, loff_t off,
152 size_t count)
153{
154 ssize_t status = 0;
155 unsigned written = 0;
156 unsigned buf_size;
157 u8 *bounce;
158
159 if (unlikely(off >= at25->chip.byte_len))
160 return -EFBIG;
161 if ((off + count) > at25->chip.byte_len)
162 count = at25->chip.byte_len - off;
163 if (unlikely(!count))
164 return count;
165
166 /* Temp buffer starts with command and address */
167 buf_size = at25->chip.page_size;
168 if (buf_size > io_limit)
169 buf_size = io_limit;
170 bounce = kmalloc(buf_size + at25->addrlen + 1, GFP_KERNEL);
171 if (!bounce)
172 return -ENOMEM;
173
174 /* For write, rollover is within the page ... so we write at
175 * most one page, then manually roll over to the next page.
176 */
177 mutex_lock(&at25->lock);
178 do {
179 unsigned long timeout, retries;
180 unsigned segment;
181 unsigned offset = (unsigned) off;
182 u8 *cp = bounce;
183 int sr;
184 u8 instr;
185
186 *cp = AT25_WREN;
187 status = spi_write(at25->spi, cp, 1);
188 if (status < 0) {
189 dev_dbg(&at25->spi->dev, "WREN --> %d\n",
190 (int) status);
191 break;
192 }
193
194 instr = AT25_WRITE;
195 if (at25->chip.flags & EE_INSTR_BIT3_IS_ADDR)
196 if (offset >= (1U << (at25->addrlen * 8)))
197 instr |= AT25_INSTR_BIT3;
198 *cp++ = instr;
199
200 /* 8/16/24-bit address is written MSB first */
201 switch (at25->addrlen) {
202 default: /* case 3 */
203 *cp++ = offset >> 16;
204 case 2:
205 *cp++ = offset >> 8;
206 case 1:
207 case 0: /* can't happen: for better codegen */
208 *cp++ = offset >> 0;
209 }
210
211 /* Write as much of a page as we can */
212 segment = buf_size - (offset % buf_size);
213 if (segment > count)
214 segment = count;
215 memcpy(cp, buf, segment);
216 status = spi_write(at25->spi, bounce,
217 segment + at25->addrlen + 1);
218 dev_dbg(&at25->spi->dev,
219 "write %u bytes at %u --> %d\n",
220 segment, offset, (int) status);
221 if (status < 0)
222 break;
223
224 /* REVISIT this should detect (or prevent) failed writes
225 * to readonly sections of the EEPROM...
226 */
227
228 /* Wait for non-busy status */
229 timeout = jiffies + msecs_to_jiffies(EE_TIMEOUT);
230 retries = 0;
231 do {
232
233 sr = spi_w8r8(at25->spi, AT25_RDSR);
234 if (sr < 0 || (sr & AT25_SR_nRDY)) {
235 dev_dbg(&at25->spi->dev,
236 "rdsr --> %d (%02x)\n", sr, sr);
237 /* at HZ=100, this is sloooow */
238 msleep(1);
239 continue;
240 }
241 if (!(sr & AT25_SR_nRDY))
242 break;
243 } while (retries++ < 3 || time_before_eq(jiffies, timeout));
244
245 if ((sr < 0) || (sr & AT25_SR_nRDY)) {
246 dev_err(&at25->spi->dev,
247 "write %d bytes offset %d, "
248 "timeout after %u msecs\n",
249 segment, offset,
250 jiffies_to_msecs(jiffies -
251 (timeout - EE_TIMEOUT)));
252 status = -ETIMEDOUT;
253 break;
254 }
255
256 off += segment;
257 buf += segment;
258 count -= segment;
259 written += segment;
260
261 } while (count > 0);
262
263 mutex_unlock(&at25->lock);
264
265 kfree(bounce);
266 return written ? written : status;
267}
268
269static int at25_regmap_write(void *context, const void *data, size_t count)
270{
271 struct at25_data *at25 = context;
272 const char *buf;
273 u32 offset;
274 size_t len;
275 int err;
276
277 memcpy(&offset, data, sizeof(offset));
278 buf = (const char *)data + sizeof(offset);
279 len = count - sizeof(offset);
280
281 err = at25_ee_write(at25, buf, offset, len);
282 if (err)
283 return err;
284 return 0;
285}
286
287static const struct regmap_bus at25_regmap_bus = {
288 .read = at25_regmap_read,
289 .write = at25_regmap_write,
290 .reg_format_endian_default = REGMAP_ENDIAN_NATIVE,
291};
292
293/*-------------------------------------------------------------------------*/
294
295static int at25_fw_to_chip(struct device *dev, struct spi_eeprom *chip)
296{
297 u32 val;
298
299 memset(chip, 0, sizeof(*chip));
300 strncpy(chip->name, "at25", sizeof(chip->name));
301
302 if (device_property_read_u32(dev, "size", &val) == 0 ||
303 device_property_read_u32(dev, "at25,byte-len", &val) == 0) {
304 chip->byte_len = val;
305 } else {
306 dev_err(dev, "Error: missing \"size\" property\n");
307 return -ENODEV;
308 }
309
310 if (device_property_read_u32(dev, "pagesize", &val) == 0 ||
311 device_property_read_u32(dev, "at25,page-size", &val) == 0) {
312 chip->page_size = (u16)val;
313 } else {
314 dev_err(dev, "Error: missing \"pagesize\" property\n");
315 return -ENODEV;
316 }
317
318 if (device_property_read_u32(dev, "at25,addr-mode", &val) == 0) {
319 chip->flags = (u16)val;
320 } else {
321 if (device_property_read_u32(dev, "address-width", &val)) {
322 dev_err(dev,
323 "Error: missing \"address-width\" property\n");
324 return -ENODEV;
325 }
326 switch (val) {
327 case 8:
328 chip->flags |= EE_ADDR1;
329 break;
330 case 16:
331 chip->flags |= EE_ADDR2;
332 break;
333 case 24:
334 chip->flags |= EE_ADDR3;
335 break;
336 default:
337 dev_err(dev,
338 "Error: bad \"address-width\" property: %u\n",
339 val);
340 return -ENODEV;
341 }
342 if (device_property_present(dev, "read-only"))
343 chip->flags |= EE_READONLY;
344 }
345 return 0;
346}
347
348static int at25_probe(struct spi_device *spi)
349{
350 struct at25_data *at25 = NULL;
351 struct spi_eeprom chip;
352 struct regmap *regmap;
353 int err;
354 int sr;
355 int addrlen;
356
357 /* Chip description */
358 if (!spi->dev.platform_data) {
359 err = at25_fw_to_chip(&spi->dev, &chip);
360 if (err)
361 return err;
362 } else
363 chip = *(struct spi_eeprom *)spi->dev.platform_data;
364
365 /* For now we only support 8/16/24 bit addressing */
366 if (chip.flags & EE_ADDR1)
367 addrlen = 1;
368 else if (chip.flags & EE_ADDR2)
369 addrlen = 2;
370 else if (chip.flags & EE_ADDR3)
371 addrlen = 3;
372 else {
373 dev_dbg(&spi->dev, "unsupported address type\n");
374 return -EINVAL;
375 }
376
377 /* Ping the chip ... the status register is pretty portable,
378 * unlike probing manufacturer IDs. We do expect that system
379 * firmware didn't write it in the past few milliseconds!
380 */
381 sr = spi_w8r8(spi, AT25_RDSR);
382 if (sr < 0 || sr & AT25_SR_nRDY) {
383 dev_dbg(&spi->dev, "rdsr --> %d (%02x)\n", sr, sr);
384 return -ENXIO;
385 }
386
387 at25 = devm_kzalloc(&spi->dev, sizeof(struct at25_data), GFP_KERNEL);
388 if (!at25)
389 return -ENOMEM;
390
391 mutex_init(&at25->lock);
392 at25->chip = chip;
393 at25->spi = spi_dev_get(spi);
394 spi_set_drvdata(spi, at25);
395 at25->addrlen = addrlen;
396
397 at25->regmap_config.reg_bits = 32;
398 at25->regmap_config.val_bits = 8;
399 at25->regmap_config.reg_stride = 1;
400 at25->regmap_config.max_register = chip.byte_len - 1;
401
402 regmap = devm_regmap_init(&spi->dev, &at25_regmap_bus, at25,
403 &at25->regmap_config);
404 if (IS_ERR(regmap)) {
405 dev_err(&spi->dev, "regmap init failed\n");
406 return PTR_ERR(regmap);
407 }
408
409 at25->nvmem_config.name = dev_name(&spi->dev);
410 at25->nvmem_config.dev = &spi->dev;
411 at25->nvmem_config.read_only = chip.flags & EE_READONLY;
412 at25->nvmem_config.root_only = true;
413 at25->nvmem_config.owner = THIS_MODULE;
414 at25->nvmem_config.compat = true;
415 at25->nvmem_config.base_dev = &spi->dev;
416
417 at25->nvmem = nvmem_register(&at25->nvmem_config);
418 if (IS_ERR(at25->nvmem))
419 return PTR_ERR(at25->nvmem);
420
421 dev_info(&spi->dev, "%d %s %s eeprom%s, pagesize %u\n",
422 (chip.byte_len < 1024)
423 ? chip.byte_len
424 : (chip.byte_len / 1024),
425 (chip.byte_len < 1024) ? "Byte" : "KByte",
426 at25->chip.name,
427 (chip.flags & EE_READONLY) ? " (readonly)" : "",
428 at25->chip.page_size);
429 return 0;
430}
431
432static int at25_remove(struct spi_device *spi)
433{
434 struct at25_data *at25;
435
436 at25 = spi_get_drvdata(spi);
437 nvmem_unregister(at25->nvmem);
438
439 return 0;
440}
441
442/*-------------------------------------------------------------------------*/
443
444static const struct of_device_id at25_of_match[] = {
445 { .compatible = "atmel,at25", },
446 { }
447};
448MODULE_DEVICE_TABLE(of, at25_of_match);
449
450static struct spi_driver at25_driver = {
451 .driver = {
452 .name = "at25",
453 .of_match_table = at25_of_match,
454 },
455 .probe = at25_probe,
456 .remove = at25_remove,
457};
458
459module_spi_driver(at25_driver);
460
461MODULE_DESCRIPTION("Driver for most SPI EEPROMs");
462MODULE_AUTHOR("David Brownell");
463MODULE_LICENSE("GPL");
464MODULE_ALIAS("spi:at25");
1/*
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
24/*
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
31struct at25_data {
32 struct spi_device *spi;
33 struct memory_accessor mem;
34 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#define AT25_INSTR_BIT3 0x08 /* Additional address bit in instr */
54
55#define EE_MAXADDRLEN 3 /* 24 bit addresses, up to 2 MBytes */
56
57/* Specs often allow 5 msec for a page write, sometimes 20 msec;
58 * it's important to recover from write timeouts.
59 */
60#define EE_TIMEOUT 25
61
62/*-------------------------------------------------------------------------*/
63
64#define io_limit PAGE_SIZE /* bytes */
65
66static ssize_t
67at25_ee_read(
68 struct at25_data *at25,
69 char *buf,
70 unsigned offset,
71 size_t count
72)
73{
74 u8 command[EE_MAXADDRLEN + 1];
75 u8 *cp;
76 ssize_t status;
77 struct spi_transfer t[2];
78 struct spi_message m;
79 u8 instr;
80
81 if (unlikely(offset >= at25->bin.size))
82 return 0;
83 if ((offset + count) > at25->bin.size)
84 count = at25->bin.size - offset;
85 if (unlikely(!count))
86 return count;
87
88 cp = command;
89
90 instr = AT25_READ;
91 if (at25->chip.flags & EE_INSTR_BIT3_IS_ADDR)
92 if (offset >= (1U << (at25->addrlen * 8)))
93 instr |= AT25_INSTR_BIT3;
94 *cp++ = instr;
95
96 /* 8/16/24-bit address is written MSB first */
97 switch (at25->addrlen) {
98 default: /* case 3 */
99 *cp++ = offset >> 16;
100 case 2:
101 *cp++ = offset >> 8;
102 case 1:
103 case 0: /* can't happen: for better codegen */
104 *cp++ = offset >> 0;
105 }
106
107 spi_message_init(&m);
108 memset(t, 0, sizeof t);
109
110 t[0].tx_buf = command;
111 t[0].len = at25->addrlen + 1;
112 spi_message_add_tail(&t[0], &m);
113
114 t[1].rx_buf = buf;
115 t[1].len = count;
116 spi_message_add_tail(&t[1], &m);
117
118 mutex_lock(&at25->lock);
119
120 /* Read it all at once.
121 *
122 * REVISIT that's potentially a problem with large chips, if
123 * other devices on the bus need to be accessed regularly or
124 * this chip is clocked very slowly
125 */
126 status = spi_sync(at25->spi, &m);
127 dev_dbg(&at25->spi->dev,
128 "read %Zd bytes at %d --> %d\n",
129 count, offset, (int) status);
130
131 mutex_unlock(&at25->lock);
132 return status ? status : count;
133}
134
135static ssize_t
136at25_bin_read(struct file *filp, struct kobject *kobj,
137 struct bin_attribute *bin_attr,
138 char *buf, loff_t off, size_t count)
139{
140 struct device *dev;
141 struct at25_data *at25;
142
143 dev = container_of(kobj, struct device, kobj);
144 at25 = dev_get_drvdata(dev);
145
146 return at25_ee_read(at25, buf, off, count);
147}
148
149
150static ssize_t
151at25_ee_write(struct at25_data *at25, const char *buf, loff_t off,
152 size_t count)
153{
154 ssize_t status = 0;
155 unsigned written = 0;
156 unsigned buf_size;
157 u8 *bounce;
158
159 if (unlikely(off >= at25->bin.size))
160 return -EFBIG;
161 if ((off + count) > at25->bin.size)
162 count = at25->bin.size - off;
163 if (unlikely(!count))
164 return count;
165
166 /* Temp buffer starts with command and address */
167 buf_size = at25->chip.page_size;
168 if (buf_size > io_limit)
169 buf_size = io_limit;
170 bounce = kmalloc(buf_size + at25->addrlen + 1, GFP_KERNEL);
171 if (!bounce)
172 return -ENOMEM;
173
174 /* For write, rollover is within the page ... so we write at
175 * most one page, then manually roll over to the next page.
176 */
177 mutex_lock(&at25->lock);
178 do {
179 unsigned long timeout, retries;
180 unsigned segment;
181 unsigned offset = (unsigned) off;
182 u8 *cp = bounce;
183 int sr;
184 u8 instr;
185
186 *cp = AT25_WREN;
187 status = spi_write(at25->spi, cp, 1);
188 if (status < 0) {
189 dev_dbg(&at25->spi->dev, "WREN --> %d\n",
190 (int) status);
191 break;
192 }
193
194 instr = AT25_WRITE;
195 if (at25->chip.flags & EE_INSTR_BIT3_IS_ADDR)
196 if (offset >= (1U << (at25->addrlen * 8)))
197 instr |= AT25_INSTR_BIT3;
198 *cp++ = instr;
199
200 /* 8/16/24-bit address is written MSB first */
201 switch (at25->addrlen) {
202 default: /* case 3 */
203 *cp++ = offset >> 16;
204 case 2:
205 *cp++ = offset >> 8;
206 case 1:
207 case 0: /* can't happen: for better codegen */
208 *cp++ = offset >> 0;
209 }
210
211 /* Write as much of a page as we can */
212 segment = buf_size - (offset % buf_size);
213 if (segment > count)
214 segment = count;
215 memcpy(cp, buf, segment);
216 status = spi_write(at25->spi, bounce,
217 segment + at25->addrlen + 1);
218 dev_dbg(&at25->spi->dev,
219 "write %u bytes at %u --> %d\n",
220 segment, offset, (int) status);
221 if (status < 0)
222 break;
223
224 /* REVISIT this should detect (or prevent) failed writes
225 * to readonly sections of the EEPROM...
226 */
227
228 /* Wait for non-busy status */
229 timeout = jiffies + msecs_to_jiffies(EE_TIMEOUT);
230 retries = 0;
231 do {
232
233 sr = spi_w8r8(at25->spi, AT25_RDSR);
234 if (sr < 0 || (sr & AT25_SR_nRDY)) {
235 dev_dbg(&at25->spi->dev,
236 "rdsr --> %d (%02x)\n", sr, sr);
237 /* at HZ=100, this is sloooow */
238 msleep(1);
239 continue;
240 }
241 if (!(sr & AT25_SR_nRDY))
242 break;
243 } while (retries++ < 3 || time_before_eq(jiffies, timeout));
244
245 if ((sr < 0) || (sr & AT25_SR_nRDY)) {
246 dev_err(&at25->spi->dev,
247 "write %d bytes offset %d, "
248 "timeout after %u msecs\n",
249 segment, offset,
250 jiffies_to_msecs(jiffies -
251 (timeout - EE_TIMEOUT)));
252 status = -ETIMEDOUT;
253 break;
254 }
255
256 off += segment;
257 buf += segment;
258 count -= segment;
259 written += segment;
260
261 } while (count > 0);
262
263 mutex_unlock(&at25->lock);
264
265 kfree(bounce);
266 return written ? written : status;
267}
268
269static ssize_t
270at25_bin_write(struct file *filp, struct kobject *kobj,
271 struct bin_attribute *bin_attr,
272 char *buf, loff_t off, size_t count)
273{
274 struct device *dev;
275 struct at25_data *at25;
276
277 dev = container_of(kobj, struct device, kobj);
278 at25 = dev_get_drvdata(dev);
279
280 return at25_ee_write(at25, buf, off, count);
281}
282
283/*-------------------------------------------------------------------------*/
284
285/* Let in-kernel code access the eeprom data. */
286
287static ssize_t at25_mem_read(struct memory_accessor *mem, char *buf,
288 off_t offset, size_t count)
289{
290 struct at25_data *at25 = container_of(mem, struct at25_data, mem);
291
292 return at25_ee_read(at25, buf, offset, count);
293}
294
295static ssize_t at25_mem_write(struct memory_accessor *mem, const char *buf,
296 off_t offset, size_t count)
297{
298 struct at25_data *at25 = container_of(mem, struct at25_data, mem);
299
300 return at25_ee_write(at25, buf, offset, count);
301}
302
303/*-------------------------------------------------------------------------*/
304
305static int at25_probe(struct spi_device *spi)
306{
307 struct at25_data *at25 = NULL;
308 const struct spi_eeprom *chip;
309 int err;
310 int sr;
311 int addrlen;
312
313 /* Chip description */
314 chip = spi->dev.platform_data;
315 if (!chip) {
316 dev_dbg(&spi->dev, "no chip description\n");
317 err = -ENODEV;
318 goto fail;
319 }
320
321 /* For now we only support 8/16/24 bit addressing */
322 if (chip->flags & EE_ADDR1)
323 addrlen = 1;
324 else if (chip->flags & EE_ADDR2)
325 addrlen = 2;
326 else if (chip->flags & EE_ADDR3)
327 addrlen = 3;
328 else {
329 dev_dbg(&spi->dev, "unsupported address type\n");
330 err = -EINVAL;
331 goto fail;
332 }
333
334 /* Ping the chip ... the status register is pretty portable,
335 * unlike probing manufacturer IDs. We do expect that system
336 * firmware didn't write it in the past few milliseconds!
337 */
338 sr = spi_w8r8(spi, AT25_RDSR);
339 if (sr < 0 || sr & AT25_SR_nRDY) {
340 dev_dbg(&spi->dev, "rdsr --> %d (%02x)\n", sr, sr);
341 err = -ENXIO;
342 goto fail;
343 }
344
345 if (!(at25 = kzalloc(sizeof *at25, GFP_KERNEL))) {
346 err = -ENOMEM;
347 goto fail;
348 }
349
350 mutex_init(&at25->lock);
351 at25->chip = *chip;
352 at25->spi = spi_dev_get(spi);
353 dev_set_drvdata(&spi->dev, at25);
354 at25->addrlen = addrlen;
355
356 /* Export the EEPROM bytes through sysfs, since that's convenient.
357 * And maybe to other kernel code; it might hold a board's Ethernet
358 * address, or board-specific calibration data generated on the
359 * manufacturing floor.
360 *
361 * Default to root-only access to the data; EEPROMs often hold data
362 * that's sensitive for read and/or write, like ethernet addresses,
363 * security codes, board-specific manufacturing calibrations, etc.
364 */
365 sysfs_bin_attr_init(&at25->bin);
366 at25->bin.attr.name = "eeprom";
367 at25->bin.attr.mode = S_IRUSR;
368 at25->bin.read = at25_bin_read;
369 at25->mem.read = at25_mem_read;
370
371 at25->bin.size = at25->chip.byte_len;
372 if (!(chip->flags & EE_READONLY)) {
373 at25->bin.write = at25_bin_write;
374 at25->bin.attr.mode |= S_IWUSR;
375 at25->mem.write = at25_mem_write;
376 }
377
378 err = sysfs_create_bin_file(&spi->dev.kobj, &at25->bin);
379 if (err)
380 goto fail;
381
382 if (chip->setup)
383 chip->setup(&at25->mem, chip->context);
384
385 dev_info(&spi->dev, "%Zd %s %s eeprom%s, pagesize %u\n",
386 (at25->bin.size < 1024)
387 ? at25->bin.size
388 : (at25->bin.size / 1024),
389 (at25->bin.size < 1024) ? "Byte" : "KByte",
390 at25->chip.name,
391 (chip->flags & EE_READONLY) ? " (readonly)" : "",
392 at25->chip.page_size);
393 return 0;
394fail:
395 dev_dbg(&spi->dev, "probe err %d\n", err);
396 kfree(at25);
397 return err;
398}
399
400static int __devexit at25_remove(struct spi_device *spi)
401{
402 struct at25_data *at25;
403
404 at25 = dev_get_drvdata(&spi->dev);
405 sysfs_remove_bin_file(&spi->dev.kobj, &at25->bin);
406 kfree(at25);
407 return 0;
408}
409
410/*-------------------------------------------------------------------------*/
411
412static struct spi_driver at25_driver = {
413 .driver = {
414 .name = "at25",
415 .owner = THIS_MODULE,
416 },
417 .probe = at25_probe,
418 .remove = __devexit_p(at25_remove),
419};
420
421module_spi_driver(at25_driver);
422
423MODULE_DESCRIPTION("Driver for most SPI EEPROMs");
424MODULE_AUTHOR("David Brownell");
425MODULE_LICENSE("GPL");
426MODULE_ALIAS("spi:at25");