1 // SPDX-License-Identifier: GPL-2.0+
2 /*
3 * An I2C driver for the Intersil ISL 12026
4 *
5 * Copyright (c) 2018 Cavium, Inc.
6 */
7 #include <linux/bcd.h>
8 #include <linux/delay.h>
9 #include <linux/i2c.h>
10 #include <linux/module.h>
11 #include <linux/mutex.h>
12 #include <linux/nvmem-provider.h>
13 #include <linux/of.h>
14 #include <linux/rtc.h>
15 #include <linux/slab.h>
16
17 /* register offsets */
18 #define ISL12026_REG_PWR 0x14
19 # define ISL12026_REG_PWR_BSW BIT(6)
20 # define ISL12026_REG_PWR_SBIB BIT(7)
21 #define ISL12026_REG_SC 0x30
22 #define ISL12026_REG_HR 0x32
23 # define ISL12026_REG_HR_MIL BIT(7) /* military or 24 hour time */
24 #define ISL12026_REG_SR 0x3f
25 # define ISL12026_REG_SR_RTCF BIT(0)
26 # define ISL12026_REG_SR_WEL BIT(1)
27 # define ISL12026_REG_SR_RWEL BIT(2)
28 # define ISL12026_REG_SR_MBZ BIT(3)
29 # define ISL12026_REG_SR_OSCF BIT(4)
30
31 /* The EEPROM array responds at i2c address 0x57 */
32 #define ISL12026_EEPROM_ADDR 0x57
33
34 #define ISL12026_PAGESIZE 16
35 #define ISL12026_NVMEM_WRITE_TIME 20
36
37 struct isl12026 {
38 struct rtc_device *rtc;
39 struct i2c_client *nvm_client;
40 };
41
isl12026_read_reg(struct i2c_client * client,int reg)42 static int isl12026_read_reg(struct i2c_client *client, int reg)
43 {
44 u8 addr[] = {0, reg};
45 u8 val;
46 int ret;
47
48 struct i2c_msg msgs[] = {
49 {
50 .addr = client->addr,
51 .flags = 0,
52 .len = sizeof(addr),
53 .buf = addr
54 }, {
55 .addr = client->addr,
56 .flags = I2C_M_RD,
57 .len = 1,
58 .buf = &val
59 }
60 };
61
62 ret = i2c_transfer(client->adapter, msgs, ARRAY_SIZE(msgs));
63 if (ret != ARRAY_SIZE(msgs)) {
64 dev_err(&client->dev, "read reg error, ret=%d\n", ret);
65 ret = ret < 0 ? ret : -EIO;
66 } else {
67 ret = val;
68 }
69
70 return ret;
71 }
72
isl12026_arm_write(struct i2c_client * client)73 static int isl12026_arm_write(struct i2c_client *client)
74 {
75 int ret;
76 u8 op[3];
77 struct i2c_msg msg = {
78 .addr = client->addr,
79 .flags = 0,
80 .len = 1,
81 .buf = op
82 };
83
84 /* Set SR.WEL */
85 op[0] = 0;
86 op[1] = ISL12026_REG_SR;
87 op[2] = ISL12026_REG_SR_WEL;
88 msg.len = 3;
89 ret = i2c_transfer(client->adapter, &msg, 1);
90 if (ret != 1) {
91 dev_err(&client->dev, "write error SR.WEL, ret=%d\n", ret);
92 ret = ret < 0 ? ret : -EIO;
93 goto out;
94 }
95
96 /* Set SR.WEL and SR.RWEL */
97 op[2] = ISL12026_REG_SR_WEL | ISL12026_REG_SR_RWEL;
98 msg.len = 3;
99 ret = i2c_transfer(client->adapter, &msg, 1);
100 if (ret != 1) {
101 dev_err(&client->dev,
102 "write error SR.WEL|SR.RWEL, ret=%d\n", ret);
103 ret = ret < 0 ? ret : -EIO;
104 goto out;
105 } else {
106 ret = 0;
107 }
108 out:
109 return ret;
110 }
111
isl12026_disarm_write(struct i2c_client * client)112 static int isl12026_disarm_write(struct i2c_client *client)
113 {
114 int ret;
115 u8 op[3] = {0, ISL12026_REG_SR, 0};
116 struct i2c_msg msg = {
117 .addr = client->addr,
118 .flags = 0,
119 .len = sizeof(op),
120 .buf = op
121 };
122
123 ret = i2c_transfer(client->adapter, &msg, 1);
124 if (ret != 1) {
125 dev_err(&client->dev,
126 "write error SR, ret=%d\n", ret);
127 ret = ret < 0 ? ret : -EIO;
128 } else {
129 ret = 0;
130 }
131
132 return ret;
133 }
134
isl12026_write_reg(struct i2c_client * client,int reg,u8 val)135 static int isl12026_write_reg(struct i2c_client *client, int reg, u8 val)
136 {
137 int ret;
138 u8 op[3] = {0, reg, val};
139 struct i2c_msg msg = {
140 .addr = client->addr,
141 .flags = 0,
142 .len = sizeof(op),
143 .buf = op
144 };
145
146 ret = isl12026_arm_write(client);
147 if (ret)
148 return ret;
149
150 ret = i2c_transfer(client->adapter, &msg, 1);
151 if (ret != 1) {
152 dev_err(&client->dev, "write error CCR, ret=%d\n", ret);
153 ret = ret < 0 ? ret : -EIO;
154 goto out;
155 }
156
157 msleep(ISL12026_NVMEM_WRITE_TIME);
158
159 ret = isl12026_disarm_write(client);
160 out:
161 return ret;
162 }
163
isl12026_rtc_set_time(struct device * dev,struct rtc_time * tm)164 static int isl12026_rtc_set_time(struct device *dev, struct rtc_time *tm)
165 {
166 struct i2c_client *client = to_i2c_client(dev);
167 int ret;
168 u8 op[10];
169 struct i2c_msg msg = {
170 .addr = client->addr,
171 .flags = 0,
172 .len = sizeof(op),
173 .buf = op
174 };
175
176 ret = isl12026_arm_write(client);
177 if (ret)
178 return ret;
179
180 /* Set the CCR registers */
181 op[0] = 0;
182 op[1] = ISL12026_REG_SC;
183 op[2] = bin2bcd(tm->tm_sec); /* SC */
184 op[3] = bin2bcd(tm->tm_min); /* MN */
185 op[4] = bin2bcd(tm->tm_hour) | ISL12026_REG_HR_MIL; /* HR */
186 op[5] = bin2bcd(tm->tm_mday); /* DT */
187 op[6] = bin2bcd(tm->tm_mon + 1); /* MO */
188 op[7] = bin2bcd(tm->tm_year % 100); /* YR */
189 op[8] = bin2bcd(tm->tm_wday & 7); /* DW */
190 op[9] = bin2bcd(tm->tm_year >= 100 ? 20 : 19); /* Y2K */
191 ret = i2c_transfer(client->adapter, &msg, 1);
192 if (ret != 1) {
193 dev_err(&client->dev, "write error CCR, ret=%d\n", ret);
194 ret = ret < 0 ? ret : -EIO;
195 goto out;
196 }
197
198 ret = isl12026_disarm_write(client);
199 out:
200 return ret;
201 }
202
isl12026_rtc_read_time(struct device * dev,struct rtc_time * tm)203 static int isl12026_rtc_read_time(struct device *dev, struct rtc_time *tm)
204 {
205 struct i2c_client *client = to_i2c_client(dev);
206 u8 ccr[8];
207 u8 addr[2];
208 u8 sr;
209 int ret;
210 struct i2c_msg msgs[] = {
211 {
212 .addr = client->addr,
213 .flags = 0,
214 .len = sizeof(addr),
215 .buf = addr
216 }, {
217 .addr = client->addr,
218 .flags = I2C_M_RD,
219 }
220 };
221
222 /* First, read SR */
223 addr[0] = 0;
224 addr[1] = ISL12026_REG_SR;
225 msgs[1].len = 1;
226 msgs[1].buf = &sr;
227
228 ret = i2c_transfer(client->adapter, msgs, ARRAY_SIZE(msgs));
229 if (ret != ARRAY_SIZE(msgs)) {
230 dev_err(&client->dev, "read error, ret=%d\n", ret);
231 ret = ret < 0 ? ret : -EIO;
232 goto out;
233 }
234
235 if (sr & ISL12026_REG_SR_RTCF)
236 dev_warn(&client->dev, "Real-Time Clock Failure on read\n");
237 if (sr & ISL12026_REG_SR_OSCF)
238 dev_warn(&client->dev, "Oscillator Failure on read\n");
239
240 /* Second, CCR regs */
241 addr[0] = 0;
242 addr[1] = ISL12026_REG_SC;
243 msgs[1].len = sizeof(ccr);
244 msgs[1].buf = ccr;
245
246 ret = i2c_transfer(client->adapter, msgs, ARRAY_SIZE(msgs));
247 if (ret != ARRAY_SIZE(msgs)) {
248 dev_err(&client->dev, "read error, ret=%d\n", ret);
249 ret = ret < 0 ? ret : -EIO;
250 goto out;
251 }
252
253 tm->tm_sec = bcd2bin(ccr[0] & 0x7F);
254 tm->tm_min = bcd2bin(ccr[1] & 0x7F);
255 if (ccr[2] & ISL12026_REG_HR_MIL)
256 tm->tm_hour = bcd2bin(ccr[2] & 0x3F);
257 else
258 tm->tm_hour = bcd2bin(ccr[2] & 0x1F) +
259 ((ccr[2] & 0x20) ? 12 : 0);
260 tm->tm_mday = bcd2bin(ccr[3] & 0x3F);
261 tm->tm_mon = bcd2bin(ccr[4] & 0x1F) - 1;
262 tm->tm_year = bcd2bin(ccr[5]);
263 if (bcd2bin(ccr[7]) == 20)
264 tm->tm_year += 100;
265 tm->tm_wday = ccr[6] & 0x07;
266
267 ret = 0;
268 out:
269 return ret;
270 }
271
272 static const struct rtc_class_ops isl12026_rtc_ops = {
273 .read_time = isl12026_rtc_read_time,
274 .set_time = isl12026_rtc_set_time,
275 };
276
isl12026_nvm_read(void * p,unsigned int offset,void * val,size_t bytes)277 static int isl12026_nvm_read(void *p, unsigned int offset,
278 void *val, size_t bytes)
279 {
280 struct isl12026 *priv = p;
281 int ret;
282 u8 addr[2];
283 struct i2c_msg msgs[] = {
284 {
285 .addr = priv->nvm_client->addr,
286 .flags = 0,
287 .len = sizeof(addr),
288 .buf = addr
289 }, {
290 .addr = priv->nvm_client->addr,
291 .flags = I2C_M_RD,
292 .buf = val
293 }
294 };
295
296 /*
297 * offset and bytes checked and limited by nvmem core, so
298 * proceed without further checks.
299 */
300 ret = mutex_lock_interruptible(&priv->rtc->ops_lock);
301 if (ret)
302 return ret;
303
304 /* 2 bytes of address, most significant first */
305 addr[0] = offset >> 8;
306 addr[1] = offset;
307 msgs[1].len = bytes;
308 ret = i2c_transfer(priv->nvm_client->adapter, msgs, ARRAY_SIZE(msgs));
309
310 mutex_unlock(&priv->rtc->ops_lock);
311
312 if (ret != ARRAY_SIZE(msgs)) {
313 dev_err(&priv->nvm_client->dev,
314 "nvmem read error, ret=%d\n", ret);
315 return ret < 0 ? ret : -EIO;
316 }
317
318 return 0;
319 }
320
isl12026_nvm_write(void * p,unsigned int offset,void * val,size_t bytes)321 static int isl12026_nvm_write(void *p, unsigned int offset,
322 void *val, size_t bytes)
323 {
324 struct isl12026 *priv = p;
325 int ret;
326 u8 *v = val;
327 size_t chunk_size, num_written;
328 u8 payload[ISL12026_PAGESIZE + 2]; /* page + 2 address bytes */
329 struct i2c_msg msgs[] = {
330 {
331 .addr = priv->nvm_client->addr,
332 .flags = 0,
333 .buf = payload
334 }
335 };
336
337 /*
338 * offset and bytes checked and limited by nvmem core, so
339 * proceed without further checks.
340 */
341 ret = mutex_lock_interruptible(&priv->rtc->ops_lock);
342 if (ret)
343 return ret;
344
345 num_written = 0;
346 while (bytes) {
347 chunk_size = round_down(offset, ISL12026_PAGESIZE) +
348 ISL12026_PAGESIZE - offset;
349 chunk_size = min(bytes, chunk_size);
350 /*
351 * 2 bytes of address, most significant first, followed
352 * by page data bytes
353 */
354 memcpy(payload + 2, v + num_written, chunk_size);
355 payload[0] = offset >> 8;
356 payload[1] = offset;
357 msgs[0].len = chunk_size + 2;
358 ret = i2c_transfer(priv->nvm_client->adapter,
359 msgs, ARRAY_SIZE(msgs));
360 if (ret != ARRAY_SIZE(msgs)) {
361 dev_err(&priv->nvm_client->dev,
362 "nvmem write error, ret=%d\n", ret);
363 ret = ret < 0 ? ret : -EIO;
364 break;
365 }
366 ret = 0;
367 bytes -= chunk_size;
368 offset += chunk_size;
369 num_written += chunk_size;
370 msleep(ISL12026_NVMEM_WRITE_TIME);
371 }
372
373 mutex_unlock(&priv->rtc->ops_lock);
374
375 return ret;
376 }
377
isl12026_force_power_modes(struct i2c_client * client)378 static void isl12026_force_power_modes(struct i2c_client *client)
379 {
380 int ret;
381 int pwr, requested_pwr;
382 u32 bsw_val, sbib_val;
383 bool set_bsw, set_sbib;
384
385 /*
386 * If we can read the of_property, set the specified value.
387 * If there is an error reading the of_property (likely
388 * because it does not exist), keep the current value.
389 */
390 ret = of_property_read_u32(client->dev.of_node,
391 "isil,pwr-bsw", &bsw_val);
392 set_bsw = (ret == 0);
393
394 ret = of_property_read_u32(client->dev.of_node,
395 "isil,pwr-sbib", &sbib_val);
396 set_sbib = (ret == 0);
397
398 /* Check if PWR.BSW and/or PWR.SBIB need specified values */
399 if (!set_bsw && !set_sbib)
400 return;
401
402 pwr = isl12026_read_reg(client, ISL12026_REG_PWR);
403 if (pwr < 0) {
404 dev_warn(&client->dev, "Error: Failed to read PWR %d\n", pwr);
405 return;
406 }
407
408 requested_pwr = pwr;
409
410 if (set_bsw) {
411 if (bsw_val)
412 requested_pwr |= ISL12026_REG_PWR_BSW;
413 else
414 requested_pwr &= ~ISL12026_REG_PWR_BSW;
415 } /* else keep current BSW */
416
417 if (set_sbib) {
418 if (sbib_val)
419 requested_pwr |= ISL12026_REG_PWR_SBIB;
420 else
421 requested_pwr &= ~ISL12026_REG_PWR_SBIB;
422 } /* else keep current SBIB */
423
424 if (pwr >= 0 && pwr != requested_pwr) {
425 dev_dbg(&client->dev, "PWR: %02x\n", pwr);
426 dev_dbg(&client->dev, "Updating PWR to: %02x\n", requested_pwr);
427 isl12026_write_reg(client, ISL12026_REG_PWR, requested_pwr);
428 }
429 }
430
isl12026_probe(struct i2c_client * client)431 static int isl12026_probe(struct i2c_client *client)
432 {
433 struct isl12026 *priv;
434 int ret;
435 struct nvmem_config nvm_cfg = {
436 .name = "isl12026-",
437 .base_dev = &client->dev,
438 .stride = 1,
439 .word_size = 1,
440 .size = 512,
441 .reg_read = isl12026_nvm_read,
442 .reg_write = isl12026_nvm_write,
443 };
444
445 if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C))
446 return -ENODEV;
447
448 priv = devm_kzalloc(&client->dev, sizeof(*priv), GFP_KERNEL);
449 if (!priv)
450 return -ENOMEM;
451
452 i2c_set_clientdata(client, priv);
453
454 isl12026_force_power_modes(client);
455
456 priv->nvm_client = i2c_new_dummy_device(client->adapter, ISL12026_EEPROM_ADDR);
457 if (IS_ERR(priv->nvm_client))
458 return PTR_ERR(priv->nvm_client);
459
460 priv->rtc = devm_rtc_allocate_device(&client->dev);
461 ret = PTR_ERR_OR_ZERO(priv->rtc);
462 if (ret)
463 return ret;
464
465 priv->rtc->ops = &isl12026_rtc_ops;
466 nvm_cfg.priv = priv;
467 ret = devm_rtc_nvmem_register(priv->rtc, &nvm_cfg);
468 if (ret)
469 return ret;
470
471 return devm_rtc_register_device(priv->rtc);
472 }
473
isl12026_remove(struct i2c_client * client)474 static void isl12026_remove(struct i2c_client *client)
475 {
476 struct isl12026 *priv = i2c_get_clientdata(client);
477
478 i2c_unregister_device(priv->nvm_client);
479 }
480
481 static const struct of_device_id isl12026_dt_match[] = {
482 { .compatible = "isil,isl12026" },
483 { }
484 };
485 MODULE_DEVICE_TABLE(of, isl12026_dt_match);
486
487 static struct i2c_driver isl12026_driver = {
488 .driver = {
489 .name = "rtc-isl12026",
490 .of_match_table = isl12026_dt_match,
491 },
492 .probe = isl12026_probe,
493 .remove = isl12026_remove,
494 };
495
496 module_i2c_driver(isl12026_driver);
497
498 MODULE_DESCRIPTION("ISL 12026 RTC driver");
499 MODULE_LICENSE("GPL");
500