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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/of_device.h>
15#include <linux/rtc.h>
16#include <linux/slab.h>
17
18/* register offsets */
19#define ISL12026_REG_PWR 0x14
20# define ISL12026_REG_PWR_BSW BIT(6)
21# define ISL12026_REG_PWR_SBIB BIT(7)
22#define ISL12026_REG_SC 0x30
23#define ISL12026_REG_HR 0x32
24# define ISL12026_REG_HR_MIL BIT(7) /* military or 24 hour time */
25#define ISL12026_REG_SR 0x3f
26# define ISL12026_REG_SR_RTCF BIT(0)
27# define ISL12026_REG_SR_WEL BIT(1)
28# define ISL12026_REG_SR_RWEL BIT(2)
29# define ISL12026_REG_SR_MBZ BIT(3)
30# define ISL12026_REG_SR_OSCF BIT(4)
31
32/* The EEPROM array responds at i2c address 0x57 */
33#define ISL12026_EEPROM_ADDR 0x57
34
35#define ISL12026_PAGESIZE 16
36#define ISL12026_NVMEM_WRITE_TIME 20
37
38struct isl12026 {
39 struct rtc_device *rtc;
40 struct i2c_client *nvm_client;
41};
42
43static int isl12026_read_reg(struct i2c_client *client, int reg)
44{
45 u8 addr[] = {0, reg};
46 u8 val;
47 int ret;
48
49 struct i2c_msg msgs[] = {
50 {
51 .addr = client->addr,
52 .flags = 0,
53 .len = sizeof(addr),
54 .buf = addr
55 }, {
56 .addr = client->addr,
57 .flags = I2C_M_RD,
58 .len = 1,
59 .buf = &val
60 }
61 };
62
63 ret = i2c_transfer(client->adapter, msgs, ARRAY_SIZE(msgs));
64 if (ret != ARRAY_SIZE(msgs)) {
65 dev_err(&client->dev, "read reg error, ret=%d\n", ret);
66 ret = ret < 0 ? ret : -EIO;
67 } else {
68 ret = val;
69 }
70
71 return ret;
72}
73
74static int isl12026_arm_write(struct i2c_client *client)
75{
76 int ret;
77 u8 op[3];
78 struct i2c_msg msg = {
79 .addr = client->addr,
80 .flags = 0,
81 .len = 1,
82 .buf = op
83 };
84
85 /* Set SR.WEL */
86 op[0] = 0;
87 op[1] = ISL12026_REG_SR;
88 op[2] = ISL12026_REG_SR_WEL;
89 msg.len = 3;
90 ret = i2c_transfer(client->adapter, &msg, 1);
91 if (ret != 1) {
92 dev_err(&client->dev, "write error SR.WEL, ret=%d\n", ret);
93 ret = ret < 0 ? ret : -EIO;
94 goto out;
95 }
96
97 /* Set SR.WEL and SR.RWEL */
98 op[2] = ISL12026_REG_SR_WEL | ISL12026_REG_SR_RWEL;
99 msg.len = 3;
100 ret = i2c_transfer(client->adapter, &msg, 1);
101 if (ret != 1) {
102 dev_err(&client->dev,
103 "write error SR.WEL|SR.RWEL, ret=%d\n", ret);
104 ret = ret < 0 ? ret : -EIO;
105 goto out;
106 } else {
107 ret = 0;
108 }
109out:
110 return ret;
111}
112
113static int isl12026_disarm_write(struct i2c_client *client)
114{
115 int ret;
116 u8 op[3] = {0, ISL12026_REG_SR, 0};
117 struct i2c_msg msg = {
118 .addr = client->addr,
119 .flags = 0,
120 .len = sizeof(op),
121 .buf = op
122 };
123
124 ret = i2c_transfer(client->adapter, &msg, 1);
125 if (ret != 1) {
126 dev_err(&client->dev,
127 "write error SR, ret=%d\n", ret);
128 ret = ret < 0 ? ret : -EIO;
129 } else {
130 ret = 0;
131 }
132
133 return ret;
134}
135
136static int isl12026_write_reg(struct i2c_client *client, int reg, u8 val)
137{
138 int ret;
139 u8 op[3] = {0, reg, val};
140 struct i2c_msg msg = {
141 .addr = client->addr,
142 .flags = 0,
143 .len = sizeof(op),
144 .buf = op
145 };
146
147 ret = isl12026_arm_write(client);
148 if (ret)
149 return ret;
150
151 ret = i2c_transfer(client->adapter, &msg, 1);
152 if (ret != 1) {
153 dev_err(&client->dev, "write error CCR, ret=%d\n", ret);
154 ret = ret < 0 ? ret : -EIO;
155 goto out;
156 }
157
158 msleep(ISL12026_NVMEM_WRITE_TIME);
159
160 ret = isl12026_disarm_write(client);
161out:
162 return ret;
163}
164
165static int isl12026_rtc_set_time(struct device *dev, struct rtc_time *tm)
166{
167 struct i2c_client *client = to_i2c_client(dev);
168 int ret;
169 u8 op[10];
170 struct i2c_msg msg = {
171 .addr = client->addr,
172 .flags = 0,
173 .len = sizeof(op),
174 .buf = op
175 };
176
177 ret = isl12026_arm_write(client);
178 if (ret)
179 return ret;
180
181 /* Set the CCR registers */
182 op[0] = 0;
183 op[1] = ISL12026_REG_SC;
184 op[2] = bin2bcd(tm->tm_sec); /* SC */
185 op[3] = bin2bcd(tm->tm_min); /* MN */
186 op[4] = bin2bcd(tm->tm_hour) | ISL12026_REG_HR_MIL; /* HR */
187 op[5] = bin2bcd(tm->tm_mday); /* DT */
188 op[6] = bin2bcd(tm->tm_mon + 1); /* MO */
189 op[7] = bin2bcd(tm->tm_year % 100); /* YR */
190 op[8] = bin2bcd(tm->tm_wday & 7); /* DW */
191 op[9] = bin2bcd(tm->tm_year >= 100 ? 20 : 19); /* Y2K */
192 ret = i2c_transfer(client->adapter, &msg, 1);
193 if (ret != 1) {
194 dev_err(&client->dev, "write error CCR, ret=%d\n", ret);
195 ret = ret < 0 ? ret : -EIO;
196 goto out;
197 }
198
199 ret = isl12026_disarm_write(client);
200out:
201 return ret;
202}
203
204static int isl12026_rtc_read_time(struct device *dev, struct rtc_time *tm)
205{
206 struct i2c_client *client = to_i2c_client(dev);
207 u8 ccr[8];
208 u8 addr[2];
209 u8 sr;
210 int ret;
211 struct i2c_msg msgs[] = {
212 {
213 .addr = client->addr,
214 .flags = 0,
215 .len = sizeof(addr),
216 .buf = addr
217 }, {
218 .addr = client->addr,
219 .flags = I2C_M_RD,
220 }
221 };
222
223 /* First, read SR */
224 addr[0] = 0;
225 addr[1] = ISL12026_REG_SR;
226 msgs[1].len = 1;
227 msgs[1].buf = &sr;
228
229 ret = i2c_transfer(client->adapter, msgs, ARRAY_SIZE(msgs));
230 if (ret != ARRAY_SIZE(msgs)) {
231 dev_err(&client->dev, "read error, ret=%d\n", ret);
232 ret = ret < 0 ? ret : -EIO;
233 goto out;
234 }
235
236 if (sr & ISL12026_REG_SR_RTCF)
237 dev_warn(&client->dev, "Real-Time Clock Failure on read\n");
238 if (sr & ISL12026_REG_SR_OSCF)
239 dev_warn(&client->dev, "Oscillator Failure on read\n");
240
241 /* Second, CCR regs */
242 addr[0] = 0;
243 addr[1] = ISL12026_REG_SC;
244 msgs[1].len = sizeof(ccr);
245 msgs[1].buf = ccr;
246
247 ret = i2c_transfer(client->adapter, msgs, ARRAY_SIZE(msgs));
248 if (ret != ARRAY_SIZE(msgs)) {
249 dev_err(&client->dev, "read error, ret=%d\n", ret);
250 ret = ret < 0 ? ret : -EIO;
251 goto out;
252 }
253
254 tm->tm_sec = bcd2bin(ccr[0] & 0x7F);
255 tm->tm_min = bcd2bin(ccr[1] & 0x7F);
256 if (ccr[2] & ISL12026_REG_HR_MIL)
257 tm->tm_hour = bcd2bin(ccr[2] & 0x3F);
258 else
259 tm->tm_hour = bcd2bin(ccr[2] & 0x1F) +
260 ((ccr[2] & 0x20) ? 12 : 0);
261 tm->tm_mday = bcd2bin(ccr[3] & 0x3F);
262 tm->tm_mon = bcd2bin(ccr[4] & 0x1F) - 1;
263 tm->tm_year = bcd2bin(ccr[5]);
264 if (bcd2bin(ccr[7]) == 20)
265 tm->tm_year += 100;
266 tm->tm_wday = ccr[6] & 0x07;
267
268 ret = 0;
269out:
270 return ret;
271}
272
273static const struct rtc_class_ops isl12026_rtc_ops = {
274 .read_time = isl12026_rtc_read_time,
275 .set_time = isl12026_rtc_set_time,
276};
277
278static int isl12026_nvm_read(void *p, unsigned int offset,
279 void *val, size_t bytes)
280{
281 struct isl12026 *priv = p;
282 int ret;
283 u8 addr[2];
284 struct i2c_msg msgs[] = {
285 {
286 .addr = priv->nvm_client->addr,
287 .flags = 0,
288 .len = sizeof(addr),
289 .buf = addr
290 }, {
291 .addr = priv->nvm_client->addr,
292 .flags = I2C_M_RD,
293 .buf = val
294 }
295 };
296
297 /*
298 * offset and bytes checked and limited by nvmem core, so
299 * proceed without further checks.
300 */
301 ret = mutex_lock_interruptible(&priv->rtc->ops_lock);
302 if (ret)
303 return ret;
304
305 /* 2 bytes of address, most significant first */
306 addr[0] = offset >> 8;
307 addr[1] = offset;
308 msgs[1].len = bytes;
309 ret = i2c_transfer(priv->nvm_client->adapter, msgs, ARRAY_SIZE(msgs));
310
311 mutex_unlock(&priv->rtc->ops_lock);
312
313 if (ret != ARRAY_SIZE(msgs)) {
314 dev_err(&priv->nvm_client->dev,
315 "nvmem read error, ret=%d\n", ret);
316 return ret < 0 ? ret : -EIO;
317 }
318
319 return 0;
320}
321
322static int isl12026_nvm_write(void *p, unsigned int offset,
323 void *val, size_t bytes)
324{
325 struct isl12026 *priv = p;
326 int ret;
327 u8 *v = val;
328 size_t chunk_size, num_written;
329 u8 payload[ISL12026_PAGESIZE + 2]; /* page + 2 address bytes */
330 struct i2c_msg msgs[] = {
331 {
332 .addr = priv->nvm_client->addr,
333 .flags = 0,
334 .buf = payload
335 }
336 };
337
338 /*
339 * offset and bytes checked and limited by nvmem core, so
340 * proceed without further checks.
341 */
342 ret = mutex_lock_interruptible(&priv->rtc->ops_lock);
343 if (ret)
344 return ret;
345
346 num_written = 0;
347 while (bytes) {
348 chunk_size = round_down(offset, ISL12026_PAGESIZE) +
349 ISL12026_PAGESIZE - offset;
350 chunk_size = min(bytes, chunk_size);
351 /*
352 * 2 bytes of address, most significant first, followed
353 * by page data bytes
354 */
355 memcpy(payload + 2, v + num_written, chunk_size);
356 payload[0] = offset >> 8;
357 payload[1] = offset;
358 msgs[0].len = chunk_size + 2;
359 ret = i2c_transfer(priv->nvm_client->adapter,
360 msgs, ARRAY_SIZE(msgs));
361 if (ret != ARRAY_SIZE(msgs)) {
362 dev_err(&priv->nvm_client->dev,
363 "nvmem write error, ret=%d\n", ret);
364 ret = ret < 0 ? ret : -EIO;
365 break;
366 }
367 ret = 0;
368 bytes -= chunk_size;
369 offset += chunk_size;
370 num_written += chunk_size;
371 msleep(ISL12026_NVMEM_WRITE_TIME);
372 }
373
374 mutex_unlock(&priv->rtc->ops_lock);
375
376 return ret;
377}
378
379static void isl12026_force_power_modes(struct i2c_client *client)
380{
381 int ret;
382 int pwr, requested_pwr;
383 u32 bsw_val, sbib_val;
384 bool set_bsw, set_sbib;
385
386 /*
387 * If we can read the of_property, set the specified value.
388 * If there is an error reading the of_property (likely
389 * because it does not exist), keep the current value.
390 */
391 ret = of_property_read_u32(client->dev.of_node,
392 "isil,pwr-bsw", &bsw_val);
393 set_bsw = (ret == 0);
394
395 ret = of_property_read_u32(client->dev.of_node,
396 "isil,pwr-sbib", &sbib_val);
397 set_sbib = (ret == 0);
398
399 /* Check if PWR.BSW and/or PWR.SBIB need specified values */
400 if (!set_bsw && !set_sbib)
401 return;
402
403 pwr = isl12026_read_reg(client, ISL12026_REG_PWR);
404 if (pwr < 0) {
405 dev_warn(&client->dev, "Error: Failed to read PWR %d\n", pwr);
406 return;
407 }
408
409 requested_pwr = pwr;
410
411 if (set_bsw) {
412 if (bsw_val)
413 requested_pwr |= ISL12026_REG_PWR_BSW;
414 else
415 requested_pwr &= ~ISL12026_REG_PWR_BSW;
416 } /* else keep current BSW */
417
418 if (set_sbib) {
419 if (sbib_val)
420 requested_pwr |= ISL12026_REG_PWR_SBIB;
421 else
422 requested_pwr &= ~ISL12026_REG_PWR_SBIB;
423 } /* else keep current SBIB */
424
425 if (pwr >= 0 && pwr != requested_pwr) {
426 dev_dbg(&client->dev, "PWR: %02x\n", pwr);
427 dev_dbg(&client->dev, "Updating PWR to: %02x\n", requested_pwr);
428 isl12026_write_reg(client, ISL12026_REG_PWR, requested_pwr);
429 }
430}
431
432static int isl12026_probe_new(struct i2c_client *client)
433{
434 struct isl12026 *priv;
435 int ret;
436 struct nvmem_config nvm_cfg = {
437 .name = "isl12026-",
438 .base_dev = &client->dev,
439 .stride = 1,
440 .word_size = 1,
441 .size = 512,
442 .reg_read = isl12026_nvm_read,
443 .reg_write = isl12026_nvm_write,
444 };
445
446 if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C))
447 return -ENODEV;
448
449 priv = devm_kzalloc(&client->dev, sizeof(*priv), GFP_KERNEL);
450 if (!priv)
451 return -ENOMEM;
452
453 i2c_set_clientdata(client, priv);
454
455 isl12026_force_power_modes(client);
456
457 priv->nvm_client = i2c_new_dummy_device(client->adapter, ISL12026_EEPROM_ADDR);
458 if (IS_ERR(priv->nvm_client))
459 return PTR_ERR(priv->nvm_client);
460
461 priv->rtc = devm_rtc_allocate_device(&client->dev);
462 ret = PTR_ERR_OR_ZERO(priv->rtc);
463 if (ret)
464 return ret;
465
466 priv->rtc->ops = &isl12026_rtc_ops;
467 nvm_cfg.priv = priv;
468 ret = devm_rtc_nvmem_register(priv->rtc, &nvm_cfg);
469 if (ret)
470 return ret;
471
472 return devm_rtc_register_device(priv->rtc);
473}
474
475static void isl12026_remove(struct i2c_client *client)
476{
477 struct isl12026 *priv = i2c_get_clientdata(client);
478
479 i2c_unregister_device(priv->nvm_client);
480}
481
482static const struct of_device_id isl12026_dt_match[] = {
483 { .compatible = "isil,isl12026" },
484 { }
485};
486MODULE_DEVICE_TABLE(of, isl12026_dt_match);
487
488static struct i2c_driver isl12026_driver = {
489 .driver = {
490 .name = "rtc-isl12026",
491 .of_match_table = isl12026_dt_match,
492 },
493 .probe_new = isl12026_probe_new,
494 .remove = isl12026_remove,
495};
496
497module_i2c_driver(isl12026_driver);
498
499MODULE_DESCRIPTION("ISL 12026 RTC driver");
500MODULE_LICENSE("GPL");