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