1// SPDX-License-Identifier: GPL-2.0
2/*
3 * Driver for Microchip 48L640 64 Kb SPI Serial EERAM
4 *
5 * Copyright Heiko Schocher <hs@denx.de>
6 *
7 * datasheet: http://ww1.microchip.com/downloads/en/DeviceDoc/20006055B.pdf
8 *
9 * we set continuous mode but reading/writing more bytes than
10 * pagesize seems to bring chip into state where readden values
11 * are wrong ... no idea why.
12 *
13 */
14#include <linux/delay.h>
15#include <linux/device.h>
16#include <linux/jiffies.h>
17#include <linux/module.h>
18#include <linux/mtd/mtd.h>
19#include <linux/mtd/partitions.h>
20#include <linux/mutex.h>
21#include <linux/sched.h>
22#include <linux/sizes.h>
23#include <linux/spi/flash.h>
24#include <linux/spi/spi.h>
25#include <linux/of.h>
26#include <linux/string_choices.h>
27
28struct mchp48_caps {
29 unsigned int size;
30 unsigned int page_size;
31 bool auto_disable_wel;
32};
33
34struct mchp48l640_flash {
35 struct spi_device *spi;
36 struct mutex lock;
37 struct mtd_info mtd;
38 const struct mchp48_caps *caps;
39};
40
41#define MCHP48L640_CMD_WREN 0x06
42#define MCHP48L640_CMD_WRDI 0x04
43#define MCHP48L640_CMD_WRITE 0x02
44#define MCHP48L640_CMD_READ 0x03
45#define MCHP48L640_CMD_WRSR 0x01
46#define MCHP48L640_CMD_RDSR 0x05
47
48#define MCHP48L640_STATUS_RDY 0x01
49#define MCHP48L640_STATUS_WEL 0x02
50#define MCHP48L640_STATUS_BP0 0x04
51#define MCHP48L640_STATUS_BP1 0x08
52#define MCHP48L640_STATUS_SWM 0x10
53#define MCHP48L640_STATUS_PRO 0x20
54#define MCHP48L640_STATUS_ASE 0x40
55
56#define MCHP48L640_TIMEOUT 100
57
58#define MAX_CMD_SIZE 0x10
59
60#define to_mchp48l640_flash(x) container_of(x, struct mchp48l640_flash, mtd)
61
62static int mchp48l640_mkcmd(struct mchp48l640_flash *flash, u8 cmd, loff_t addr, char *buf)
63{
64 buf[0] = cmd;
65 buf[1] = addr >> 8;
66 buf[2] = addr;
67
68 return 3;
69}
70
71static int mchp48l640_read_status(struct mchp48l640_flash *flash, int *status)
72{
73 unsigned char cmd[2];
74 int ret;
75
76 cmd[0] = MCHP48L640_CMD_RDSR;
77 cmd[1] = 0x00;
78 mutex_lock(&flash->lock);
79 ret = spi_write_then_read(spi: flash->spi, txbuf: &cmd[0], n_tx: 1, rxbuf: &cmd[1], n_rx: 1);
80 mutex_unlock(lock: &flash->lock);
81 if (!ret)
82 *status = cmd[1];
83 dev_dbg(&flash->spi->dev, "read status ret: %d status: %x", ret, *status);
84
85 return ret;
86}
87
88static int mchp48l640_waitforbit(struct mchp48l640_flash *flash, int bit, bool set)
89{
90 int ret, status;
91 unsigned long deadline;
92
93 deadline = jiffies + msecs_to_jiffies(MCHP48L640_TIMEOUT);
94 do {
95 ret = mchp48l640_read_status(flash, status: &status);
96 dev_dbg(&flash->spi->dev, "read status ret: %d bit: %x %sset status: %x",
97 ret, bit, (set ? "" : "not"), status);
98 if (ret)
99 return ret;
100
101 if (set) {
102 if ((status & bit) == bit)
103 return 0;
104 } else {
105 if ((status & bit) == 0)
106 return 0;
107 }
108
109 usleep_range(min: 1000, max: 2000);
110 } while (!time_after_eq(jiffies, deadline));
111
112 dev_err(&flash->spi->dev, "Timeout waiting for bit %x %s set in status register.",
113 bit, (set ? "" : "not"));
114 return -ETIMEDOUT;
115}
116
117static int mchp48l640_write_prepare(struct mchp48l640_flash *flash, bool enable)
118{
119 unsigned char cmd[2];
120 int ret;
121
122 if (enable)
123 cmd[0] = MCHP48L640_CMD_WREN;
124 else
125 cmd[0] = MCHP48L640_CMD_WRDI;
126
127 mutex_lock(&flash->lock);
128 ret = spi_write(spi: flash->spi, buf: cmd, len: 1);
129 mutex_unlock(lock: &flash->lock);
130
131 if (ret)
132 dev_err(&flash->spi->dev, "write %s failed ret: %d",
133 str_enable_disable(enable), ret);
134
135 dev_dbg(&flash->spi->dev, "write %s success ret: %d",
136 str_enable_disable(enable), ret);
137 if (enable)
138 return mchp48l640_waitforbit(flash, MCHP48L640_STATUS_WEL, set: true);
139
140 return ret;
141}
142
143static int mchp48l640_set_mode(struct mchp48l640_flash *flash)
144{
145 unsigned char cmd[2];
146 int ret;
147
148 ret = mchp48l640_write_prepare(flash, enable: true);
149 if (ret)
150 return ret;
151
152 cmd[0] = MCHP48L640_CMD_WRSR;
153 cmd[1] = MCHP48L640_STATUS_PRO;
154
155 mutex_lock(&flash->lock);
156 ret = spi_write(spi: flash->spi, buf: cmd, len: 2);
157 mutex_unlock(lock: &flash->lock);
158 if (ret)
159 dev_err(&flash->spi->dev, "Could not set continuous mode ret: %d", ret);
160
161 return mchp48l640_waitforbit(flash, MCHP48L640_STATUS_PRO, set: true);
162}
163
164static int mchp48l640_wait_rdy(struct mchp48l640_flash *flash)
165{
166 return mchp48l640_waitforbit(flash, MCHP48L640_STATUS_RDY, set: false);
167};
168
169static int mchp48l640_write_page(struct mtd_info *mtd, loff_t to, size_t len,
170 size_t *retlen, const unsigned char *buf)
171{
172 struct mchp48l640_flash *flash = to_mchp48l640_flash(mtd);
173 unsigned char *cmd;
174 int ret;
175 int cmdlen;
176
177 cmd = kmalloc((3 + len), GFP_KERNEL | GFP_DMA);
178 if (!cmd)
179 return -ENOMEM;
180
181 ret = mchp48l640_wait_rdy(flash);
182 if (ret)
183 goto fail;
184
185 ret = mchp48l640_write_prepare(flash, enable: true);
186 if (ret)
187 goto fail;
188
189 mutex_lock(&flash->lock);
190 cmdlen = mchp48l640_mkcmd(flash, MCHP48L640_CMD_WRITE, addr: to, buf: cmd);
191 memcpy(&cmd[cmdlen], buf, len);
192 ret = spi_write(spi: flash->spi, buf: cmd, len: cmdlen + len);
193 mutex_unlock(lock: &flash->lock);
194 if (!ret)
195 *retlen += len;
196 else
197 goto fail;
198
199 if (flash->caps->auto_disable_wel) {
200 ret = mchp48l640_waitforbit(flash, MCHP48L640_STATUS_WEL, set: false);
201 if (ret)
202 goto fail;
203 } else {
204 ret = mchp48l640_write_prepare(flash, enable: false);
205 if (ret)
206 goto fail;
207 }
208
209 kfree(objp: cmd);
210 return 0;
211fail:
212 kfree(objp: cmd);
213 dev_err(&flash->spi->dev, "write fail with: %d", ret);
214 return ret;
215};
216
217static int mchp48l640_write(struct mtd_info *mtd, loff_t to, size_t len,
218 size_t *retlen, const unsigned char *buf)
219{
220 struct mchp48l640_flash *flash = to_mchp48l640_flash(mtd);
221 int ret;
222 size_t wlen = 0;
223 loff_t woff = to;
224 size_t ws;
225 size_t page_sz = flash->caps->page_size;
226
227 /*
228 * we set PRO bit (page rollover), but writing length > page size
229 * does result in total chaos, so write in 32 byte chunks.
230 */
231 while (wlen < len) {
232 ws = min((len - wlen), page_sz);
233 ret = mchp48l640_write_page(mtd, to: woff, len: ws, retlen, buf: &buf[wlen]);
234 if (ret)
235 return ret;
236 wlen += ws;
237 woff += ws;
238 }
239
240 return 0;
241}
242
243static int mchp48l640_read_page(struct mtd_info *mtd, loff_t from, size_t len,
244 size_t *retlen, unsigned char *buf)
245{
246 struct mchp48l640_flash *flash = to_mchp48l640_flash(mtd);
247 unsigned char *cmd;
248 int ret;
249 int cmdlen;
250
251 cmd = kmalloc((3 + len), GFP_KERNEL | GFP_DMA);
252 if (!cmd)
253 return -ENOMEM;
254
255 ret = mchp48l640_wait_rdy(flash);
256 if (ret)
257 goto fail;
258
259 mutex_lock(&flash->lock);
260 cmdlen = mchp48l640_mkcmd(flash, MCHP48L640_CMD_READ, addr: from, buf: cmd);
261 ret = spi_write_then_read(spi: flash->spi, txbuf: cmd, n_tx: cmdlen, rxbuf: buf, n_rx: len);
262 mutex_unlock(lock: &flash->lock);
263 if (!ret)
264 *retlen += len;
265
266 kfree(objp: cmd);
267 return ret;
268
269fail:
270 kfree(objp: cmd);
271 dev_err(&flash->spi->dev, "read fail with: %d", ret);
272 return ret;
273}
274
275static int mchp48l640_read(struct mtd_info *mtd, loff_t from, size_t len,
276 size_t *retlen, unsigned char *buf)
277{
278 struct mchp48l640_flash *flash = to_mchp48l640_flash(mtd);
279 int ret;
280 size_t wlen = 0;
281 loff_t woff = from;
282 size_t ws;
283 size_t page_sz = flash->caps->page_size;
284
285 /*
286 * we set PRO bit (page rollover), but if read length > page size
287 * does result in total chaos in result ...
288 */
289 while (wlen < len) {
290 ws = min((len - wlen), page_sz);
291 ret = mchp48l640_read_page(mtd, from: woff, len: ws, retlen, buf: &buf[wlen]);
292 if (ret)
293 return ret;
294 wlen += ws;
295 woff += ws;
296 }
297
298 return 0;
299};
300
301static const struct mchp48_caps mchp48l640_caps = {
302 .size = SZ_8K,
303 .page_size = 32,
304 .auto_disable_wel = true,
305};
306
307static const struct mchp48_caps mb85rs128ty_caps = {
308 .size = SZ_16K,
309 .page_size = 256,
310 .auto_disable_wel = false,
311};
312
313static int mchp48l640_probe(struct spi_device *spi)
314{
315 struct mchp48l640_flash *flash;
316 struct flash_platform_data *data;
317 int err;
318 int status;
319
320 flash = devm_kzalloc(dev: &spi->dev, size: sizeof(*flash), GFP_KERNEL);
321 if (!flash)
322 return -ENOMEM;
323
324 flash->spi = spi;
325 mutex_init(&flash->lock);
326 spi_set_drvdata(spi, data: flash);
327
328 err = mchp48l640_read_status(flash, status: &status);
329 if (err)
330 return err;
331
332 err = mchp48l640_set_mode(flash);
333 if (err)
334 return err;
335
336 data = dev_get_platdata(dev: &spi->dev);
337
338 flash->caps = of_device_get_match_data(dev: &spi->dev);
339 if (!flash->caps)
340 flash->caps = &mchp48l640_caps;
341
342 mtd_set_of_node(mtd: &flash->mtd, np: spi->dev.of_node);
343 flash->mtd.dev.parent = &spi->dev;
344 flash->mtd.type = MTD_RAM;
345 flash->mtd.flags = MTD_CAP_RAM;
346 flash->mtd.writesize = flash->caps->page_size;
347 flash->mtd.size = flash->caps->size;
348 flash->mtd._read = mchp48l640_read;
349 flash->mtd._write = mchp48l640_write;
350
351 err = mtd_device_register(&flash->mtd, data ? data->parts : NULL,
352 data ? data->nr_parts : 0);
353 if (err)
354 return err;
355
356 return 0;
357}
358
359static void mchp48l640_remove(struct spi_device *spi)
360{
361 struct mchp48l640_flash *flash = spi_get_drvdata(spi);
362
363 WARN_ON(mtd_device_unregister(&flash->mtd));
364}
365
366static const struct of_device_id mchp48l640_of_table[] = {
367 {
368 .compatible = "microchip,48l640",
369 .data = &mchp48l640_caps,
370 },
371 {
372 .compatible = "fujitsu,mb85rs128ty",
373 .data = &mb85rs128ty_caps,
374 },
375 {}
376};
377MODULE_DEVICE_TABLE(of, mchp48l640_of_table);
378
379static const struct spi_device_id mchp48l640_spi_ids[] = {
380 {
381 .name = "48l640",
382 .driver_data = (kernel_ulong_t)&mchp48l640_caps,
383 },
384 {
385 .name = "mb85rs128ty",
386 .driver_data = (kernel_ulong_t)&mb85rs128ty_caps,
387 },
388 {}
389};
390MODULE_DEVICE_TABLE(spi, mchp48l640_spi_ids);
391
392static struct spi_driver mchp48l640_driver = {
393 .driver = {
394 .name = "mchp48l640",
395 .of_match_table = mchp48l640_of_table,
396 },
397 .probe = mchp48l640_probe,
398 .remove = mchp48l640_remove,
399 .id_table = mchp48l640_spi_ids,
400};
401
402module_spi_driver(mchp48l640_driver);
403
404MODULE_DESCRIPTION("MTD SPI driver for Microchip 48l640 EERAM chips");
405MODULE_AUTHOR("Heiko Schocher <hs@denx.de>");
406MODULE_LICENSE("GPL v2");
407MODULE_ALIAS("spi:mchp48l640");
408

source code of linux/drivers/mtd/devices/mchp48l640.c