1/*
2 * sst25l.c
3 *
4 * Driver for SST25L SPI Flash chips
5 *
6 * Copyright © 2009 Bluewater Systems Ltd
7 * Author: Andre Renaud <andre@bluewatersys.com>
8 * Author: Ryan Mallon
9 *
10 * Based on m25p80.c
11 *
12 * This code is free software; you can redistribute it and/or modify
13 * it under the terms of the GNU General Public License version 2 as
14 * published by the Free Software Foundation.
15 *
16 */
17
18#include <linux/init.h>
19#include <linux/module.h>
20#include <linux/device.h>
21#include <linux/mutex.h>
22#include <linux/interrupt.h>
23#include <linux/slab.h>
24#include <linux/sched.h>
25
26#include <linux/mtd/mtd.h>
27#include <linux/mtd/partitions.h>
28
29#include <linux/spi/spi.h>
30#include <linux/spi/flash.h>
31
32/* Erases can take up to 3 seconds! */
33#define MAX_READY_WAIT_JIFFIES	msecs_to_jiffies(3000)
34
35#define SST25L_CMD_WRSR		0x01	/* Write status register */
36#define SST25L_CMD_WRDI		0x04	/* Write disable */
37#define SST25L_CMD_RDSR		0x05	/* Read status register */
38#define SST25L_CMD_WREN		0x06	/* Write enable */
39#define SST25L_CMD_READ		0x03	/* High speed read */
40
41#define SST25L_CMD_EWSR		0x50	/* Enable write status register */
42#define SST25L_CMD_SECTOR_ERASE	0x20	/* Erase sector */
43#define SST25L_CMD_READ_ID	0x90	/* Read device ID */
44#define SST25L_CMD_AAI_PROGRAM	0xaf	/* Auto address increment */
45
46#define SST25L_STATUS_BUSY	(1 << 0)	/* Chip is busy */
47#define SST25L_STATUS_WREN	(1 << 1)	/* Write enabled */
48#define SST25L_STATUS_BP0	(1 << 2)	/* Block protection 0 */
49#define SST25L_STATUS_BP1	(1 << 3)	/* Block protection 1 */
50
51struct sst25l_flash {
52	struct spi_device	*spi;
53	struct mutex		lock;
54	struct mtd_info		mtd;
55};
56
57struct flash_info {
58	const char		*name;
59	uint16_t		device_id;
60	unsigned		page_size;
61	unsigned		nr_pages;
62	unsigned		erase_size;
63};
64
65#define to_sst25l_flash(x) container_of(x, struct sst25l_flash, mtd)
66
67static struct flash_info __devinitdata sst25l_flash_info[] = {
68	{"sst25lf020a", 0xbf43, 256, 1024, 4096},
69	{"sst25lf040a",	0xbf44,	256, 2048, 4096},
70};
71
72static int sst25l_status(struct sst25l_flash *flash, int *status)
73{
74	struct spi_message m;
75	struct spi_transfer t;
76	unsigned char cmd_resp[2];
77	int err;
78
79	spi_message_init(&m);
80	memset(&t, 0, sizeof(struct spi_transfer));
81
82	cmd_resp[0] = SST25L_CMD_RDSR;
83	cmd_resp[1] = 0xff;
84	t.tx_buf = cmd_resp;
85	t.rx_buf = cmd_resp;
86	t.len = sizeof(cmd_resp);
87	spi_message_add_tail(&t, &m);
88	err = spi_sync(flash->spi, &m);
89	if (err < 0)
90		return err;
91
92	*status = cmd_resp[1];
93	return 0;
94}
95
96static int sst25l_write_enable(struct sst25l_flash *flash, int enable)
97{
98	unsigned char command[2];
99	int status, err;
100
101	command[0] = enable ? SST25L_CMD_WREN : SST25L_CMD_WRDI;
102	err = spi_write(flash->spi, command, 1);
103	if (err)
104		return err;
105
106	command[0] = SST25L_CMD_EWSR;
107	err = spi_write(flash->spi, command, 1);
108	if (err)
109		return err;
110
111	command[0] = SST25L_CMD_WRSR;
112	command[1] = enable ? 0 : SST25L_STATUS_BP0 | SST25L_STATUS_BP1;
113	err = spi_write(flash->spi, command, 2);
114	if (err)
115		return err;
116
117	if (enable) {
118		err = sst25l_status(flash, &status);
119		if (err)
120			return err;
121		if (!(status & SST25L_STATUS_WREN))
122			return -EROFS;
123	}
124
125	return 0;
126}
127
128static int sst25l_wait_till_ready(struct sst25l_flash *flash)
129{
130	unsigned long deadline;
131	int status, err;
132
133	deadline = jiffies + MAX_READY_WAIT_JIFFIES;
134	do {
135		err = sst25l_status(flash, &status);
136		if (err)
137			return err;
138		if (!(status & SST25L_STATUS_BUSY))
139			return 0;
140
141		cond_resched();
142	} while (!time_after_eq(jiffies, deadline));
143
144	return -ETIMEDOUT;
145}
146
147static int sst25l_erase_sector(struct sst25l_flash *flash, uint32_t offset)
148{
149	unsigned char command[4];
150	int err;
151
152	err = sst25l_write_enable(flash, 1);
153	if (err)
154		return err;
155
156	command[0] = SST25L_CMD_SECTOR_ERASE;
157	command[1] = offset >> 16;
158	command[2] = offset >> 8;
159	command[3] = offset;
160	err = spi_write(flash->spi, command, 4);
161	if (err)
162		return err;
163
164	err = sst25l_wait_till_ready(flash);
165	if (err)
166		return err;
167
168	return sst25l_write_enable(flash, 0);
169}
170
171static int sst25l_erase(struct mtd_info *mtd, struct erase_info *instr)
172{
173	struct sst25l_flash *flash = to_sst25l_flash(mtd);
174	uint32_t addr, end;
175	int err;
176
177	/* Sanity checks */
178	if ((uint32_t)instr->len % mtd->erasesize)
179		return -EINVAL;
180
181	if ((uint32_t)instr->addr % mtd->erasesize)
182		return -EINVAL;
183
184	addr = instr->addr;
185	end = addr + instr->len;
186
187	mutex_lock(&flash->lock);
188
189	err = sst25l_wait_till_ready(flash);
190	if (err) {
191		mutex_unlock(&flash->lock);
192		return err;
193	}
194
195	while (addr < end) {
196		err = sst25l_erase_sector(flash, addr);
197		if (err) {
198			mutex_unlock(&flash->lock);
199			instr->state = MTD_ERASE_FAILED;
200			dev_err(&flash->spi->dev, "Erase failed\n");
201			return err;
202		}
203
204		addr += mtd->erasesize;
205	}
206
207	mutex_unlock(&flash->lock);
208
209	instr->state = MTD_ERASE_DONE;
210	mtd_erase_callback(instr);
211	return 0;
212}
213
214static int sst25l_read(struct mtd_info *mtd, loff_t from, size_t len,
215		       size_t *retlen, unsigned char *buf)
216{
217	struct sst25l_flash *flash = to_sst25l_flash(mtd);
218	struct spi_transfer transfer[2];
219	struct spi_message message;
220	unsigned char command[4];
221	int ret;
222
223	spi_message_init(&message);
224	memset(&transfer, 0, sizeof(transfer));
225
226	command[0] = SST25L_CMD_READ;
227	command[1] = from >> 16;
228	command[2] = from >> 8;
229	command[3] = from;
230
231	transfer[0].tx_buf = command;
232	transfer[0].len = sizeof(command);
233	spi_message_add_tail(&transfer[0], &message);
234
235	transfer[1].rx_buf = buf;
236	transfer[1].len = len;
237	spi_message_add_tail(&transfer[1], &message);
238
239	mutex_lock(&flash->lock);
240
241	/* Wait for previous write/erase to complete */
242	ret = sst25l_wait_till_ready(flash);
243	if (ret) {
244		mutex_unlock(&flash->lock);
245		return ret;
246	}
247
248	spi_sync(flash->spi, &message);
249
250	if (retlen && message.actual_length > sizeof(command))
251		*retlen += message.actual_length - sizeof(command);
252
253	mutex_unlock(&flash->lock);
254	return 0;
255}
256
257static int sst25l_write(struct mtd_info *mtd, loff_t to, size_t len,
258			size_t *retlen, const unsigned char *buf)
259{
260	struct sst25l_flash *flash = to_sst25l_flash(mtd);
261	int i, j, ret, bytes, copied = 0;
262	unsigned char command[5];
263
264	if ((uint32_t)to % mtd->writesize)
265		return -EINVAL;
266
267	mutex_lock(&flash->lock);
268
269	ret = sst25l_write_enable(flash, 1);
270	if (ret)
271		goto out;
272
273	for (i = 0; i < len; i += mtd->writesize) {
274		ret = sst25l_wait_till_ready(flash);
275		if (ret)
276			goto out;
277
278		/* Write the first byte of the page */
279		command[0] = SST25L_CMD_AAI_PROGRAM;
280		command[1] = (to + i) >> 16;
281		command[2] = (to + i) >> 8;
282		command[3] = (to + i);
283		command[4] = buf[i];
284		ret = spi_write(flash->spi, command, 5);
285		if (ret < 0)
286			goto out;
287		copied++;
288
289		/*
290		 * Write the remaining bytes using auto address
291		 * increment mode
292		 */
293		bytes = min_t(uint32_t, mtd->writesize, len - i);
294		for (j = 1; j < bytes; j++, copied++) {
295			ret = sst25l_wait_till_ready(flash);
296			if (ret)
297				goto out;
298
299			command[1] = buf[i + j];
300			ret = spi_write(flash->spi, command, 2);
301			if (ret)
302				goto out;
303		}
304	}
305
306out:
307	ret = sst25l_write_enable(flash, 0);
308
309	if (retlen)
310		*retlen = copied;
311
312	mutex_unlock(&flash->lock);
313	return ret;
314}
315
316static struct flash_info *__devinit sst25l_match_device(struct spi_device *spi)
317{
318	struct flash_info *flash_info = NULL;
319	struct spi_message m;
320	struct spi_transfer t;
321	unsigned char cmd_resp[6];
322	int i, err;
323	uint16_t id;
324
325	spi_message_init(&m);
326	memset(&t, 0, sizeof(struct spi_transfer));
327
328	cmd_resp[0] = SST25L_CMD_READ_ID;
329	cmd_resp[1] = 0;
330	cmd_resp[2] = 0;
331	cmd_resp[3] = 0;
332	cmd_resp[4] = 0xff;
333	cmd_resp[5] = 0xff;
334	t.tx_buf = cmd_resp;
335	t.rx_buf = cmd_resp;
336	t.len = sizeof(cmd_resp);
337	spi_message_add_tail(&t, &m);
338	err = spi_sync(spi, &m);
339	if (err < 0) {
340		dev_err(&spi->dev, "error reading device id\n");
341		return NULL;
342	}
343
344	id = (cmd_resp[4] << 8) | cmd_resp[5];
345
346	for (i = 0; i < ARRAY_SIZE(sst25l_flash_info); i++)
347		if (sst25l_flash_info[i].device_id == id)
348			flash_info = &sst25l_flash_info[i];
349
350	if (!flash_info)
351		dev_err(&spi->dev, "unknown id %.4x\n", id);
352
353	return flash_info;
354}
355
356static int __devinit sst25l_probe(struct spi_device *spi)
357{
358	struct flash_info *flash_info;
359	struct sst25l_flash *flash;
360	struct flash_platform_data *data;
361	int ret;
362
363	flash_info = sst25l_match_device(spi);
364	if (!flash_info)
365		return -ENODEV;
366
367	flash = kzalloc(sizeof(struct sst25l_flash), GFP_KERNEL);
368	if (!flash)
369		return -ENOMEM;
370
371	flash->spi = spi;
372	mutex_init(&flash->lock);
373	dev_set_drvdata(&spi->dev, flash);
374
375	data = spi->dev.platform_data;
376	if (data && data->name)
377		flash->mtd.name = data->name;
378	else
379		flash->mtd.name = dev_name(&spi->dev);
380
381	flash->mtd.type		= MTD_NORFLASH;
382	flash->mtd.flags	= MTD_CAP_NORFLASH;
383	flash->mtd.erasesize	= flash_info->erase_size;
384	flash->mtd.writesize	= flash_info->page_size;
385	flash->mtd.writebufsize	= flash_info->page_size;
386	flash->mtd.size		= flash_info->page_size * flash_info->nr_pages;
387	flash->mtd._erase	= sst25l_erase;
388	flash->mtd._read		= sst25l_read;
389	flash->mtd._write 	= sst25l_write;
390
391	dev_info(&spi->dev, "%s (%lld KiB)\n", flash_info->name,
392		 (long long)flash->mtd.size >> 10);
393
394	pr_debug("mtd .name = %s, .size = 0x%llx (%lldMiB) "
395	      ".erasesize = 0x%.8x (%uKiB) .numeraseregions = %d\n",
396	      flash->mtd.name,
397	      (long long)flash->mtd.size, (long long)(flash->mtd.size >> 20),
398	      flash->mtd.erasesize, flash->mtd.erasesize / 1024,
399	      flash->mtd.numeraseregions);
400
401
402	ret = mtd_device_parse_register(&flash->mtd, NULL, NULL,
403					data ? data->parts : NULL,
404					data ? data->nr_parts : 0);
405	if (ret) {
406		kfree(flash);
407		dev_set_drvdata(&spi->dev, NULL);
408		return -ENODEV;
409	}
410
411	return 0;
412}
413
414static int __devexit sst25l_remove(struct spi_device *spi)
415{
416	struct sst25l_flash *flash = dev_get_drvdata(&spi->dev);
417	int ret;
418
419	ret = mtd_device_unregister(&flash->mtd);
420	if (ret == 0)
421		kfree(flash);
422	return ret;
423}
424
425static struct spi_driver sst25l_driver = {
426	.driver = {
427		.name	= "sst25l",
428		.owner	= THIS_MODULE,
429	},
430	.probe		= sst25l_probe,
431	.remove		= __devexit_p(sst25l_remove),
432};
433
434module_spi_driver(sst25l_driver);
435
436MODULE_DESCRIPTION("MTD SPI driver for SST25L Flash chips");
437MODULE_AUTHOR("Andre Renaud <andre@bluewatersys.com>, "
438	      "Ryan Mallon");
439MODULE_LICENSE("GPL");
440