1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17#include <linux/module.h>
18#include <linux/kernel.h>
19#include <linux/device.h>
20#include <linux/printk.h>
21#include <linux/spi/spi.h>
22#include <linux/rtc.h>
23#include <linux/of.h>
24#include <linux/bcd.h>
25#include <linux/delay.h>
26
27
28#define MCP795_EEREAD 0x03
29#define MCP795_EEWRITE 0x02
30#define MCP795_EEWRDI 0x04
31#define MCP795_EEWREN 0x06
32#define MCP795_SRREAD 0x05
33#define MCP795_SRWRITE 0x01
34#define MCP795_READ 0x13
35#define MCP795_WRITE 0x12
36#define MCP795_UNLOCK 0x14
37#define MCP795_IDWRITE 0x32
38#define MCP795_IDREAD 0x33
39#define MCP795_CLRWDT 0x44
40#define MCP795_CLRRAM 0x54
41
42
43#define MCP795_REG_SECONDS 0x01
44#define MCP795_REG_DAY 0x04
45#define MCP795_REG_MONTH 0x06
46#define MCP795_REG_CONTROL 0x08
47#define MCP795_REG_ALM0_SECONDS 0x0C
48#define MCP795_REG_ALM0_DAY 0x0F
49
50#define MCP795_ST_BIT BIT(7)
51#define MCP795_24_BIT BIT(6)
52#define MCP795_LP_BIT BIT(5)
53#define MCP795_EXTOSC_BIT BIT(3)
54#define MCP795_OSCON_BIT BIT(5)
55#define MCP795_ALM0_BIT BIT(4)
56#define MCP795_ALM1_BIT BIT(5)
57#define MCP795_ALM0IF_BIT BIT(3)
58#define MCP795_ALM0C0_BIT BIT(4)
59#define MCP795_ALM0C1_BIT BIT(5)
60#define MCP795_ALM0C2_BIT BIT(6)
61
62#define SEC_PER_DAY (24 * 60 * 60)
63
64static int mcp795_rtcc_read(struct device *dev, u8 addr, u8 *buf, u8 count)
65{
66 struct spi_device *spi = to_spi_device(dev);
67 int ret;
68 u8 tx[2];
69
70 tx[0] = MCP795_READ;
71 tx[1] = addr;
72 ret = spi_write_then_read(spi, tx, sizeof(tx), buf, count);
73
74 if (ret)
75 dev_err(dev, "Failed reading %d bytes from address %x.\n",
76 count, addr);
77
78 return ret;
79}
80
81static int mcp795_rtcc_write(struct device *dev, u8 addr, u8 *data, u8 count)
82{
83 struct spi_device *spi = to_spi_device(dev);
84 int ret;
85 u8 tx[257];
86
87 tx[0] = MCP795_WRITE;
88 tx[1] = addr;
89 memcpy(&tx[2], data, count);
90
91 ret = spi_write(spi, tx, 2 + count);
92
93 if (ret)
94 dev_err(dev, "Failed to write %d bytes to address %x.\n",
95 count, addr);
96
97 return ret;
98}
99
100static int mcp795_rtcc_set_bits(struct device *dev, u8 addr, u8 mask, u8 state)
101{
102 int ret;
103 u8 tmp;
104
105 ret = mcp795_rtcc_read(dev, addr, &tmp, 1);
106 if (ret)
107 return ret;
108
109 if ((tmp & mask) != state) {
110 tmp = (tmp & ~mask) | state;
111 ret = mcp795_rtcc_write(dev, addr, &tmp, 1);
112 }
113
114 return ret;
115}
116
117static int mcp795_stop_oscillator(struct device *dev, bool *extosc)
118{
119 int retries = 5;
120 int ret;
121 u8 data;
122
123 ret = mcp795_rtcc_set_bits(dev, MCP795_REG_SECONDS, MCP795_ST_BIT, 0);
124 if (ret)
125 return ret;
126 ret = mcp795_rtcc_read(dev, MCP795_REG_CONTROL, &data, 1);
127 if (ret)
128 return ret;
129 *extosc = !!(data & MCP795_EXTOSC_BIT);
130 ret = mcp795_rtcc_set_bits(
131 dev, MCP795_REG_CONTROL, MCP795_EXTOSC_BIT, 0);
132 if (ret)
133 return ret;
134
135 do {
136 usleep_range(700, 800);
137 ret = mcp795_rtcc_read(dev, MCP795_REG_DAY, &data, 1);
138 if (ret)
139 break;
140 if (!(data & MCP795_OSCON_BIT))
141 break;
142
143 } while (--retries);
144
145 return !retries ? -EIO : ret;
146}
147
148static int mcp795_start_oscillator(struct device *dev, bool *extosc)
149{
150 if (extosc) {
151 u8 data = *extosc ? MCP795_EXTOSC_BIT : 0;
152 int ret;
153
154 ret = mcp795_rtcc_set_bits(
155 dev, MCP795_REG_CONTROL, MCP795_EXTOSC_BIT, data);
156 if (ret)
157 return ret;
158 }
159 return mcp795_rtcc_set_bits(
160 dev, MCP795_REG_SECONDS, MCP795_ST_BIT, MCP795_ST_BIT);
161}
162
163
164static int mcp795_update_alarm(struct device *dev, bool enable)
165{
166 int ret;
167
168 dev_dbg(dev, "%s alarm\n", enable ? "Enable" : "Disable");
169
170 if (enable) {
171
172 ret = mcp795_rtcc_set_bits(dev, MCP795_REG_ALM0_DAY,
173 MCP795_ALM0IF_BIT, 0);
174 if (ret)
175 return ret;
176
177 ret = mcp795_rtcc_set_bits(dev, MCP795_REG_CONTROL,
178 MCP795_ALM0_BIT, MCP795_ALM0_BIT);
179 } else {
180
181 ret = mcp795_rtcc_set_bits(dev, MCP795_REG_CONTROL,
182 MCP795_ALM0_BIT | MCP795_ALM1_BIT, 0);
183 }
184 return ret;
185}
186
187static int mcp795_set_time(struct device *dev, struct rtc_time *tim)
188{
189 int ret;
190 u8 data[7];
191 bool extosc;
192
193
194 ret = mcp795_stop_oscillator(dev, &extosc);
195 if (ret)
196 return ret;
197
198
199 ret = mcp795_rtcc_read(dev, MCP795_REG_SECONDS, data, sizeof(data));
200
201 if (ret)
202 return ret;
203
204 data[0] = (data[0] & 0x80) | bin2bcd(tim->tm_sec);
205 data[1] = (data[1] & 0x80) | bin2bcd(tim->tm_min);
206 data[2] = bin2bcd(tim->tm_hour);
207 data[3] = (data[3] & 0xF8) | bin2bcd(tim->tm_wday + 1);
208 data[4] = bin2bcd(tim->tm_mday);
209 data[5] = (data[5] & MCP795_LP_BIT) | bin2bcd(tim->tm_mon + 1);
210
211 if (tim->tm_year > 100)
212 tim->tm_year -= 100;
213
214 data[6] = bin2bcd(tim->tm_year);
215
216
217
218
219
220 ret = mcp795_rtcc_write(dev, MCP795_REG_SECONDS, data, 5);
221 if (ret)
222 return ret;
223
224 ret = mcp795_rtcc_write(dev, MCP795_REG_MONTH, &data[5], 2);
225 if (ret)
226 return ret;
227
228
229
230
231
232 ret = mcp795_start_oscillator(dev, extosc ? &extosc : NULL);
233 if (ret)
234 return ret;
235
236 dev_dbg(dev, "Set mcp795: %04d-%02d-%02d(%d) %02d:%02d:%02d\n",
237 tim->tm_year + 1900, tim->tm_mon, tim->tm_mday,
238 tim->tm_wday, tim->tm_hour, tim->tm_min, tim->tm_sec);
239
240 return 0;
241}
242
243static int mcp795_read_time(struct device *dev, struct rtc_time *tim)
244{
245 int ret;
246 u8 data[7];
247
248 ret = mcp795_rtcc_read(dev, MCP795_REG_SECONDS, data, sizeof(data));
249
250 if (ret)
251 return ret;
252
253 tim->tm_sec = bcd2bin(data[0] & 0x7F);
254 tim->tm_min = bcd2bin(data[1] & 0x7F);
255 tim->tm_hour = bcd2bin(data[2] & 0x3F);
256 tim->tm_wday = bcd2bin(data[3] & 0x07) - 1;
257 tim->tm_mday = bcd2bin(data[4] & 0x3F);
258 tim->tm_mon = bcd2bin(data[5] & 0x1F) - 1;
259 tim->tm_year = bcd2bin(data[6]) + 100;
260
261 dev_dbg(dev, "Read from mcp795: %04d-%02d-%02d(%d) %02d:%02d:%02d\n",
262 tim->tm_year + 1900, tim->tm_mon, tim->tm_mday,
263 tim->tm_wday, tim->tm_hour, tim->tm_min, tim->tm_sec);
264
265 return 0;
266}
267
268static int mcp795_set_alarm(struct device *dev, struct rtc_wkalrm *alm)
269{
270 struct rtc_time now_tm;
271 time64_t now;
272 time64_t later;
273 u8 tmp[6];
274 int ret;
275
276
277 ret = mcp795_read_time(dev, &now_tm);
278 if (ret)
279 return ret;
280
281 now = rtc_tm_to_time64(&now_tm);
282 later = rtc_tm_to_time64(&alm->time);
283 if (later <= now)
284 return -EINVAL;
285
286 if ((later - now) >=
287 (SEC_PER_DAY * (365 + is_leap_year(alm->time.tm_year))))
288 return -EDOM;
289
290 ret = mcp795_update_alarm(dev, false);
291 if (ret)
292 return ret;
293
294 ret = mcp795_rtcc_read(dev, MCP795_REG_ALM0_SECONDS, tmp, sizeof(tmp));
295 if (ret)
296 return ret;
297
298 alm->time.tm_year = -1;
299 alm->time.tm_isdst = -1;
300 alm->time.tm_yday = -1;
301
302 tmp[0] = (tmp[0] & 0x80) | bin2bcd(alm->time.tm_sec);
303 tmp[1] = (tmp[1] & 0x80) | bin2bcd(alm->time.tm_min);
304 tmp[2] = (tmp[2] & 0xE0) | bin2bcd(alm->time.tm_hour);
305 tmp[3] = (tmp[3] & 0x80) | bin2bcd(alm->time.tm_wday + 1);
306
307 tmp[3] |= (MCP795_ALM0C2_BIT | MCP795_ALM0C1_BIT | MCP795_ALM0C0_BIT);
308 tmp[4] = (tmp[4] & 0xC0) | bin2bcd(alm->time.tm_mday);
309 tmp[5] = (tmp[5] & 0xE0) | bin2bcd(alm->time.tm_mon + 1);
310
311 ret = mcp795_rtcc_write(dev, MCP795_REG_ALM0_SECONDS, tmp, sizeof(tmp));
312 if (ret)
313 return ret;
314
315
316 if (alm->enabled) {
317 ret = mcp795_update_alarm(dev, true);
318 if (ret)
319 return ret;
320 dev_dbg(dev, "Alarm IRQ armed\n");
321 }
322 dev_dbg(dev, "Set alarm: %02d-%02d(%d) %02d:%02d:%02d\n",
323 alm->time.tm_mon, alm->time.tm_mday, alm->time.tm_wday,
324 alm->time.tm_hour, alm->time.tm_min, alm->time.tm_sec);
325 return 0;
326}
327
328static int mcp795_read_alarm(struct device *dev, struct rtc_wkalrm *alm)
329{
330 u8 data[6];
331 int ret;
332
333 ret = mcp795_rtcc_read(
334 dev, MCP795_REG_ALM0_SECONDS, data, sizeof(data));
335 if (ret)
336 return ret;
337
338 alm->time.tm_sec = bcd2bin(data[0] & 0x7F);
339 alm->time.tm_min = bcd2bin(data[1] & 0x7F);
340 alm->time.tm_hour = bcd2bin(data[2] & 0x1F);
341 alm->time.tm_wday = bcd2bin(data[3] & 0x07) - 1;
342 alm->time.tm_mday = bcd2bin(data[4] & 0x3F);
343 alm->time.tm_mon = bcd2bin(data[5] & 0x1F) - 1;
344 alm->time.tm_year = -1;
345 alm->time.tm_isdst = -1;
346 alm->time.tm_yday = -1;
347
348 dev_dbg(dev, "Read alarm: %02d-%02d(%d) %02d:%02d:%02d\n",
349 alm->time.tm_mon, alm->time.tm_mday, alm->time.tm_wday,
350 alm->time.tm_hour, alm->time.tm_min, alm->time.tm_sec);
351 return 0;
352}
353
354static int mcp795_alarm_irq_enable(struct device *dev, unsigned int enabled)
355{
356 return mcp795_update_alarm(dev, !!enabled);
357}
358
359static irqreturn_t mcp795_irq(int irq, void *data)
360{
361 struct spi_device *spi = data;
362 struct rtc_device *rtc = spi_get_drvdata(spi);
363 struct mutex *lock = &rtc->ops_lock;
364 int ret;
365
366 mutex_lock(lock);
367
368
369
370
371
372 ret = mcp795_update_alarm(&spi->dev, false);
373 if (ret)
374 dev_err(&spi->dev,
375 "Failed to disable alarm in IRQ (ret=%d)\n", ret);
376 rtc_update_irq(rtc, 1, RTC_AF | RTC_IRQF);
377
378 mutex_unlock(lock);
379
380 return IRQ_HANDLED;
381}
382
383static const struct rtc_class_ops mcp795_rtc_ops = {
384 .read_time = mcp795_read_time,
385 .set_time = mcp795_set_time,
386 .read_alarm = mcp795_read_alarm,
387 .set_alarm = mcp795_set_alarm,
388 .alarm_irq_enable = mcp795_alarm_irq_enable
389};
390
391static int mcp795_probe(struct spi_device *spi)
392{
393 struct rtc_device *rtc;
394 int ret;
395
396 spi->mode = SPI_MODE_0;
397 spi->bits_per_word = 8;
398 ret = spi_setup(spi);
399 if (ret) {
400 dev_err(&spi->dev, "Unable to setup SPI\n");
401 return ret;
402 }
403
404
405 mcp795_start_oscillator(&spi->dev, NULL);
406
407 mcp795_rtcc_set_bits(&spi->dev, 0x03, MCP795_24_BIT, 0);
408
409 rtc = devm_rtc_device_register(&spi->dev, "rtc-mcp795",
410 &mcp795_rtc_ops, THIS_MODULE);
411 if (IS_ERR(rtc))
412 return PTR_ERR(rtc);
413
414 spi_set_drvdata(spi, rtc);
415
416 if (spi->irq > 0) {
417 dev_dbg(&spi->dev, "Alarm support enabled\n");
418
419
420
421
422 mcp795_rtcc_set_bits(&spi->dev, MCP795_REG_ALM0_DAY,
423 MCP795_ALM0IF_BIT, 0);
424 ret = devm_request_threaded_irq(&spi->dev, spi->irq, NULL,
425 mcp795_irq, IRQF_TRIGGER_FALLING | IRQF_ONESHOT,
426 dev_name(&rtc->dev), spi);
427 if (ret)
428 dev_err(&spi->dev, "Failed to request IRQ: %d: %d\n",
429 spi->irq, ret);
430 else
431 device_init_wakeup(&spi->dev, true);
432 }
433 return 0;
434}
435
436#ifdef CONFIG_OF
437static const struct of_device_id mcp795_of_match[] = {
438 { .compatible = "maxim,mcp795" },
439 { }
440};
441MODULE_DEVICE_TABLE(of, mcp795_of_match);
442#endif
443
444static struct spi_driver mcp795_driver = {
445 .driver = {
446 .name = "rtc-mcp795",
447 .of_match_table = of_match_ptr(mcp795_of_match),
448 },
449 .probe = mcp795_probe,
450};
451
452module_spi_driver(mcp795_driver);
453
454MODULE_DESCRIPTION("MCP795 RTC SPI Driver");
455MODULE_AUTHOR("Josef Gajdusek <atx@atx.name>");
456MODULE_LICENSE("GPL");
457MODULE_ALIAS("spi:mcp795");
458
