1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * sst25l.c
4 *
5 * Driver for SST25L SPI Flash chips
6 *
7 * Copyright �� 2009 Bluewater Systems Ltd
8 * Author: Andre Renaud <andre@bluewatersys.com>
9 * Author: Ryan Mallon
10 *
11 * Based on m25p80.c
12 */
13
14#include <linux/module.h>
15#include <linux/device.h>
16#include <linux/mutex.h>
17#include <linux/interrupt.h>
18#include <linux/slab.h>
19#include <linux/sched.h>
20
21#include <linux/mtd/mtd.h>
22#include <linux/mtd/partitions.h>
23
24#include <linux/spi/spi.h>
25#include <linux/spi/flash.h>
26
27/* Erases can take up to 3 seconds! */
28#define MAX_READY_WAIT_JIFFIES	msecs_to_jiffies(3000)
29
30#define SST25L_CMD_WRSR		0x01	/* Write status register */
31#define SST25L_CMD_WRDI		0x04	/* Write disable */
32#define SST25L_CMD_RDSR		0x05	/* Read status register */
33#define SST25L_CMD_WREN		0x06	/* Write enable */
34#define SST25L_CMD_READ		0x03	/* High speed read */
35
36#define SST25L_CMD_EWSR		0x50	/* Enable write status register */
37#define SST25L_CMD_SECTOR_ERASE	0x20	/* Erase sector */
38#define SST25L_CMD_READ_ID	0x90	/* Read device ID */
39#define SST25L_CMD_AAI_PROGRAM	0xaf	/* Auto address increment */
40
41#define SST25L_STATUS_BUSY	(1 << 0)	/* Chip is busy */
42#define SST25L_STATUS_WREN	(1 << 1)	/* Write enabled */
43#define SST25L_STATUS_BP0	(1 << 2)	/* Block protection 0 */
44#define SST25L_STATUS_BP1	(1 << 3)	/* Block protection 1 */
45
46struct sst25l_flash {
47	struct spi_device	*spi;
48	struct mutex		lock;
49	struct mtd_info		mtd;
50};
51
52struct flash_info {
53	const char		*name;
54	uint16_t		device_id;
55	unsigned		page_size;
56	unsigned		nr_pages;
57	unsigned		erase_size;
58};
59
60#define to_sst25l_flash(x) container_of(x, struct sst25l_flash, mtd)
61
62static struct flash_info sst25l_flash_info[] = {
63	{"sst25lf020a", 0xbf43, 256, 1024, 4096},
64	{"sst25lf040a",	0xbf44,	256, 2048, 4096},
65};
66
67static int sst25l_status(struct sst25l_flash *flash, int *status)
68{
69	struct spi_message m;
70	struct spi_transfer t;
71	unsigned char cmd_resp[2];
72	int err;
73
74	spi_message_init(&m);
75	memset(&t, 0, sizeof(struct spi_transfer));
76
77	cmd_resp[0] = SST25L_CMD_RDSR;
78	cmd_resp[1] = 0xff;
79	t.tx_buf = cmd_resp;
80	t.rx_buf = cmd_resp;
81	t.len = sizeof(cmd_resp);
82	spi_message_add_tail(&t, &m);
83	err = spi_sync(flash->spi, &m);
84	if (err < 0)
85		return err;
86
87	*status = cmd_resp[1];
88	return 0;
89}
90
91static int sst25l_write_enable(struct sst25l_flash *flash, int enable)
92{
93	unsigned char command[2];
94	int status, err;
95
96	command[0] = enable ? SST25L_CMD_WREN : SST25L_CMD_WRDI;
97	err = spi_write(flash->spi, command, 1);
98	if (err)
99		return err;
100
101	command[0] = SST25L_CMD_EWSR;
102	err = spi_write(flash->spi, command, 1);
103	if (err)
104		return err;
105
106	command[0] = SST25L_CMD_WRSR;
107	command[1] = enable ? 0 : SST25L_STATUS_BP0 | SST25L_STATUS_BP1;
108	err = spi_write(flash->spi, command, 2);
109	if (err)
110		return err;
111
112	if (enable) {
113		err = sst25l_status(flash, &status);
114		if (err)
115			return err;
116		if (!(status & SST25L_STATUS_WREN))
117			return -EROFS;
118	}
119
120	return 0;
121}
122
123static int sst25l_wait_till_ready(struct sst25l_flash *flash)
124{
125	unsigned long deadline;
126	int status, err;
127
128	deadline = jiffies + MAX_READY_WAIT_JIFFIES;
129	do {
130		err = sst25l_status(flash, &status);
131		if (err)
132			return err;
133		if (!(status & SST25L_STATUS_BUSY))
134			return 0;
135
136		cond_resched();
137	} while (!time_after_eq(jiffies, deadline));
138
139	return -ETIMEDOUT;
140}
141
142static int sst25l_erase_sector(struct sst25l_flash *flash, uint32_t offset)
143{
144	unsigned char command[4];
145	int err;
146
147	err = sst25l_write_enable(flash, 1);
148	if (err)
149		return err;
150
151	command[0] = SST25L_CMD_SECTOR_ERASE;
152	command[1] = offset >> 16;
153	command[2] = offset >> 8;
154	command[3] = offset;
155	err = spi_write(flash->spi, command, 4);
156	if (err)
157		return err;
158
159	err = sst25l_wait_till_ready(flash);
160	if (err)
161		return err;
162
163	return sst25l_write_enable(flash, 0);
164}
165
166static int sst25l_erase(struct mtd_info *mtd, struct erase_info *instr)
167{
168	struct sst25l_flash *flash = to_sst25l_flash(mtd);
169	uint32_t addr, end;
170	int err;
171
172	/* Sanity checks */
173	if ((uint32_t)instr->len % mtd->erasesize)
174		return -EINVAL;
175
176	if ((uint32_t)instr->addr % mtd->erasesize)
177		return -EINVAL;
178
179	addr = instr->addr;
180	end = addr + instr->len;
181
182	mutex_lock(&flash->lock);
183
184	err = sst25l_wait_till_ready(flash);
185	if (err) {
186		mutex_unlock(&flash->lock);
187		return err;
188	}
189
190	while (addr < end) {
191		err = sst25l_erase_sector(flash, addr);
192		if (err) {
193			mutex_unlock(&flash->lock);
194			dev_err(&flash->spi->dev, "Erase failed\n");
195			return err;
196		}
197
198		addr += mtd->erasesize;
199	}
200
201	mutex_unlock(&flash->lock);
202
203	return 0;
204}
205
206static int sst25l_read(struct mtd_info *mtd, loff_t from, size_t len,
207		       size_t *retlen, unsigned char *buf)
208{
209	struct sst25l_flash *flash = to_sst25l_flash(mtd);
210	struct spi_transfer transfer[2];
211	struct spi_message message;
212	unsigned char command[4];
213	int ret;
214
215	spi_message_init(&message);
216	memset(&transfer, 0, sizeof(transfer));
217
218	command[0] = SST25L_CMD_READ;
219	command[1] = from >> 16;
220	command[2] = from >> 8;
221	command[3] = from;
222
223	transfer[0].tx_buf = command;
224	transfer[0].len = sizeof(command);
225	spi_message_add_tail(&transfer[0], &message);
226
227	transfer[1].rx_buf = buf;
228	transfer[1].len = len;
229	spi_message_add_tail(&transfer[1], &message);
230
231	mutex_lock(&flash->lock);
232
233	/* Wait for previous write/erase to complete */
234	ret = sst25l_wait_till_ready(flash);
235	if (ret) {
236		mutex_unlock(&flash->lock);
237		return ret;
238	}
239
240	spi_sync(flash->spi, &message);
241
242	if (retlen && message.actual_length > sizeof(command))
243		*retlen += message.actual_length - sizeof(command);
244
245	mutex_unlock(&flash->lock);
246	return 0;
247}
248
249static int sst25l_write(struct mtd_info *mtd, loff_t to, size_t len,
250			size_t *retlen, const unsigned char *buf)
251{
252	struct sst25l_flash *flash = to_sst25l_flash(mtd);
253	int i, j, ret, bytes, copied = 0;
254	unsigned char command[5];
255
256	if ((uint32_t)to % mtd->writesize)
257		return -EINVAL;
258
259	mutex_lock(&flash->lock);
260
261	ret = sst25l_write_enable(flash, 1);
262	if (ret)
263		goto out;
264
265	for (i = 0; i < len; i += mtd->writesize) {
266		ret = sst25l_wait_till_ready(flash);
267		if (ret)
268			goto out;
269
270		/* Write the first byte of the page */
271		command[0] = SST25L_CMD_AAI_PROGRAM;
272		command[1] = (to + i) >> 16;
273		command[2] = (to + i) >> 8;
274		command[3] = (to + i);
275		command[4] = buf[i];
276		ret = spi_write(flash->spi, command, 5);
277		if (ret < 0)
278			goto out;
279		copied++;
280
281		/*
282		 * Write the remaining bytes using auto address
283		 * increment mode
284		 */
285		bytes = min_t(uint32_t, mtd->writesize, len - i);
286		for (j = 1; j < bytes; j++, copied++) {
287			ret = sst25l_wait_till_ready(flash);
288			if (ret)
289				goto out;
290
291			command[1] = buf[i + j];
292			ret = spi_write(flash->spi, command, 2);
293			if (ret)
294				goto out;
295		}
296	}
297
298out:
299	ret = sst25l_write_enable(flash, 0);
300
301	if (retlen)
302		*retlen = copied;
303
304	mutex_unlock(&flash->lock);
305	return ret;
306}
307
308static struct flash_info *sst25l_match_device(struct spi_device *spi)
309{
310	struct flash_info *flash_info = NULL;
311	struct spi_message m;
312	struct spi_transfer t;
313	unsigned char cmd_resp[6];
314	int i, err;
315	uint16_t id;
316
317	spi_message_init(&m);
318	memset(&t, 0, sizeof(struct spi_transfer));
319
320	cmd_resp[0] = SST25L_CMD_READ_ID;
321	cmd_resp[1] = 0;
322	cmd_resp[2] = 0;
323	cmd_resp[3] = 0;
324	cmd_resp[4] = 0xff;
325	cmd_resp[5] = 0xff;
326	t.tx_buf = cmd_resp;
327	t.rx_buf = cmd_resp;
328	t.len = sizeof(cmd_resp);
329	spi_message_add_tail(&t, &m);
330	err = spi_sync(spi, &m);
331	if (err < 0) {
332		dev_err(&spi->dev, "error reading device id\n");
333		return NULL;
334	}
335
336	id = (cmd_resp[4] << 8) | cmd_resp[5];
337
338	for (i = 0; i < ARRAY_SIZE(sst25l_flash_info); i++)
339		if (sst25l_flash_info[i].device_id == id)
340			flash_info = &sst25l_flash_info[i];
341
342	if (!flash_info)
343		dev_err(&spi->dev, "unknown id %.4x\n", id);
344
345	return flash_info;
346}
347
348static int sst25l_probe(struct spi_device *spi)
349{
350	struct flash_info *flash_info;
351	struct sst25l_flash *flash;
352	struct flash_platform_data *data;
353	int ret;
354
355	flash_info = sst25l_match_device(spi);
356	if (!flash_info)
357		return -ENODEV;
358
359	flash = devm_kzalloc(&spi->dev, sizeof(*flash), GFP_KERNEL);
360	if (!flash)
361		return -ENOMEM;
362
363	flash->spi = spi;
364	mutex_init(&flash->lock);
365	spi_set_drvdata(spi, flash);
366
367	data = dev_get_platdata(&spi->dev);
368	if (data && data->name)
369		flash->mtd.name = data->name;
370
371	flash->mtd.dev.parent   = &spi->dev;
372	flash->mtd.type		= MTD_NORFLASH;
373	flash->mtd.flags	= MTD_CAP_NORFLASH;
374	flash->mtd.erasesize	= flash_info->erase_size;
375	flash->mtd.writesize	= flash_info->page_size;
376	flash->mtd.writebufsize	= flash_info->page_size;
377	flash->mtd.size		= flash_info->page_size * flash_info->nr_pages;
378	flash->mtd._erase	= sst25l_erase;
379	flash->mtd._read		= sst25l_read;
380	flash->mtd._write 	= sst25l_write;
381
382	dev_info(&spi->dev, "%s (%lld KiB)\n", flash_info->name,
383		 (long long)flash->mtd.size >> 10);
384
385	pr_debug("mtd .name = %s, .size = 0x%llx (%lldMiB) "
386	      ".erasesize = 0x%.8x (%uKiB) .numeraseregions = %d\n",
387	      flash->mtd.name,
388	      (long long)flash->mtd.size, (long long)(flash->mtd.size >> 20),
389	      flash->mtd.erasesize, flash->mtd.erasesize / 1024,
390	      flash->mtd.numeraseregions);
391
392
393	ret = mtd_device_register(&flash->mtd, data ? data->parts : NULL,
394				  data ? data->nr_parts : 0);
395	if (ret)
396		return -ENODEV;
397
398	return 0;
399}
400
401static void sst25l_remove(struct spi_device *spi)
402{
403	struct sst25l_flash *flash = spi_get_drvdata(spi);
404
405	WARN_ON(mtd_device_unregister(&flash->mtd));
406}
407
408static struct spi_driver sst25l_driver = {
409	.driver = {
410		.name	= "sst25l",
411	},
412	.probe		= sst25l_probe,
413	.remove		= sst25l_remove,
414};
415
416module_spi_driver(sst25l_driver);
417
418MODULE_DESCRIPTION("MTD SPI driver for SST25L Flash chips");
419MODULE_AUTHOR("Andre Renaud <andre@bluewatersys.com>, "
420	      "Ryan Mallon");
421MODULE_LICENSE("GPL");
422