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1/*
2 * Copyright (C) 2012 Avionic Design GmbH
3 *
4 * This program is free software; you can redistribute it and/or modify
5 * it under the terms of the GNU General Public License version 2 as
6 * published by the Free Software Foundation.
7 */
8
9#include <linux/bcd.h>
10#include <linux/i2c.h>
11#include <linux/module.h>
12#include <linux/rtc.h>
13#include <linux/of.h>
14
15#define DRIVER_NAME "rtc-pcf8523"
16
17#define REG_CONTROL1 0x00
18#define REG_CONTROL1_CAP_SEL (1 << 7)
19#define REG_CONTROL1_STOP (1 << 5)
20
21#define REG_CONTROL3 0x02
22#define REG_CONTROL3_PM_BLD (1 << 7) /* battery low detection disabled */
23#define REG_CONTROL3_PM_VDD (1 << 6) /* switch-over disabled */
24#define REG_CONTROL3_PM_DSM (1 << 5) /* direct switching mode */
25#define REG_CONTROL3_PM_MASK 0xe0
26#define REG_CONTROL3_BLF (1 << 2) /* battery low bit, read-only */
27
28#define REG_SECONDS 0x03
29#define REG_SECONDS_OS (1 << 7)
30
31#define REG_MINUTES 0x04
32#define REG_HOURS 0x05
33#define REG_DAYS 0x06
34#define REG_WEEKDAYS 0x07
35#define REG_MONTHS 0x08
36#define REG_YEARS 0x09
37
38struct pcf8523 {
39 struct rtc_device *rtc;
40};
41
42static int pcf8523_read(struct i2c_client *client, u8 reg, u8 *valuep)
43{
44 struct i2c_msg msgs[2];
45 u8 value = 0;
46 int err;
47
48 msgs[0].addr = client->addr;
49 msgs[0].flags = 0;
50 msgs[0].len = sizeof(reg);
51 msgs[0].buf = ®
52
53 msgs[1].addr = client->addr;
54 msgs[1].flags = I2C_M_RD;
55 msgs[1].len = sizeof(value);
56 msgs[1].buf = &value;
57
58 err = i2c_transfer(client->adapter, msgs, ARRAY_SIZE(msgs));
59 if (err < 0)
60 return err;
61
62 *valuep = value;
63
64 return 0;
65}
66
67static int pcf8523_write(struct i2c_client *client, u8 reg, u8 value)
68{
69 u8 buffer[2] = { reg, value };
70 struct i2c_msg msg;
71 int err;
72
73 msg.addr = client->addr;
74 msg.flags = 0;
75 msg.len = sizeof(buffer);
76 msg.buf = buffer;
77
78 err = i2c_transfer(client->adapter, &msg, 1);
79 if (err < 0)
80 return err;
81
82 return 0;
83}
84
85static int pcf8523_select_capacitance(struct i2c_client *client, bool high)
86{
87 u8 value;
88 int err;
89
90 err = pcf8523_read(client, REG_CONTROL1, &value);
91 if (err < 0)
92 return err;
93
94 if (!high)
95 value &= ~REG_CONTROL1_CAP_SEL;
96 else
97 value |= REG_CONTROL1_CAP_SEL;
98
99 err = pcf8523_write(client, REG_CONTROL1, value);
100 if (err < 0)
101 return err;
102
103 return err;
104}
105
106static int pcf8523_set_pm(struct i2c_client *client, u8 pm)
107{
108 u8 value;
109 int err;
110
111 err = pcf8523_read(client, REG_CONTROL3, &value);
112 if (err < 0)
113 return err;
114
115 value = (value & ~REG_CONTROL3_PM_MASK) | pm;
116
117 err = pcf8523_write(client, REG_CONTROL3, value);
118 if (err < 0)
119 return err;
120
121 return 0;
122}
123
124static int pcf8523_stop_rtc(struct i2c_client *client)
125{
126 u8 value;
127 int err;
128
129 err = pcf8523_read(client, REG_CONTROL1, &value);
130 if (err < 0)
131 return err;
132
133 value |= REG_CONTROL1_STOP;
134
135 err = pcf8523_write(client, REG_CONTROL1, value);
136 if (err < 0)
137 return err;
138
139 return 0;
140}
141
142static int pcf8523_start_rtc(struct i2c_client *client)
143{
144 u8 value;
145 int err;
146
147 err = pcf8523_read(client, REG_CONTROL1, &value);
148 if (err < 0)
149 return err;
150
151 value &= ~REG_CONTROL1_STOP;
152
153 err = pcf8523_write(client, REG_CONTROL1, value);
154 if (err < 0)
155 return err;
156
157 return 0;
158}
159
160static int pcf8523_rtc_read_time(struct device *dev, struct rtc_time *tm)
161{
162 struct i2c_client *client = to_i2c_client(dev);
163 u8 start = REG_SECONDS, regs[7];
164 struct i2c_msg msgs[2];
165 int err;
166
167 msgs[0].addr = client->addr;
168 msgs[0].flags = 0;
169 msgs[0].len = 1;
170 msgs[0].buf = &start;
171
172 msgs[1].addr = client->addr;
173 msgs[1].flags = I2C_M_RD;
174 msgs[1].len = sizeof(regs);
175 msgs[1].buf = regs;
176
177 err = i2c_transfer(client->adapter, msgs, ARRAY_SIZE(msgs));
178 if (err < 0)
179 return err;
180
181 if (regs[0] & REG_SECONDS_OS)
182 return -EINVAL;
183
184 tm->tm_sec = bcd2bin(regs[0] & 0x7f);
185 tm->tm_min = bcd2bin(regs[1] & 0x7f);
186 tm->tm_hour = bcd2bin(regs[2] & 0x3f);
187 tm->tm_mday = bcd2bin(regs[3] & 0x3f);
188 tm->tm_wday = regs[4] & 0x7;
189 tm->tm_mon = bcd2bin(regs[5] & 0x1f) - 1;
190 tm->tm_year = bcd2bin(regs[6]) + 100;
191
192 return rtc_valid_tm(tm);
193}
194
195static int pcf8523_rtc_set_time(struct device *dev, struct rtc_time *tm)
196{
197 struct i2c_client *client = to_i2c_client(dev);
198 struct i2c_msg msg;
199 u8 regs[8];
200 int err;
201
202 /*
203 * The hardware can only store values between 0 and 99 in it's YEAR
204 * register (with 99 overflowing to 0 on increment).
205 * After 2100-02-28 we could start interpreting the year to be in the
206 * interval [2100, 2199], but there is no path to switch in a smooth way
207 * because the chip handles YEAR=0x00 (and the out-of-spec
208 * YEAR=0xa0) as a leap year, but 2100 isn't.
209 */
210 if (tm->tm_year < 100 || tm->tm_year >= 200)
211 return -EINVAL;
212
213 err = pcf8523_stop_rtc(client);
214 if (err < 0)
215 return err;
216
217 regs[0] = REG_SECONDS;
218 /* This will purposely overwrite REG_SECONDS_OS */
219 regs[1] = bin2bcd(tm->tm_sec);
220 regs[2] = bin2bcd(tm->tm_min);
221 regs[3] = bin2bcd(tm->tm_hour);
222 regs[4] = bin2bcd(tm->tm_mday);
223 regs[5] = tm->tm_wday;
224 regs[6] = bin2bcd(tm->tm_mon + 1);
225 regs[7] = bin2bcd(tm->tm_year - 100);
226
227 msg.addr = client->addr;
228 msg.flags = 0;
229 msg.len = sizeof(regs);
230 msg.buf = regs;
231
232 err = i2c_transfer(client->adapter, &msg, 1);
233 if (err < 0) {
234 /*
235 * If the time cannot be set, restart the RTC anyway. Note
236 * that errors are ignored if the RTC cannot be started so
237 * that we have a chance to propagate the original error.
238 */
239 pcf8523_start_rtc(client);
240 return err;
241 }
242
243 return pcf8523_start_rtc(client);
244}
245
246#ifdef CONFIG_RTC_INTF_DEV
247static int pcf8523_rtc_ioctl(struct device *dev, unsigned int cmd,
248 unsigned long arg)
249{
250 struct i2c_client *client = to_i2c_client(dev);
251 u8 value;
252 int ret = 0, err;
253
254 switch (cmd) {
255 case RTC_VL_READ:
256 err = pcf8523_read(client, REG_CONTROL3, &value);
257 if (err < 0)
258 return err;
259
260 if (value & REG_CONTROL3_BLF)
261 ret = 1;
262
263 if (copy_to_user((void __user *)arg, &ret, sizeof(int)))
264 return -EFAULT;
265
266 return 0;
267 default:
268 return -ENOIOCTLCMD;
269 }
270}
271#else
272#define pcf8523_rtc_ioctl NULL
273#endif
274
275static const struct rtc_class_ops pcf8523_rtc_ops = {
276 .read_time = pcf8523_rtc_read_time,
277 .set_time = pcf8523_rtc_set_time,
278 .ioctl = pcf8523_rtc_ioctl,
279};
280
281static int pcf8523_probe(struct i2c_client *client,
282 const struct i2c_device_id *id)
283{
284 struct pcf8523 *pcf;
285 int err;
286
287 if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C))
288 return -ENODEV;
289
290 pcf = devm_kzalloc(&client->dev, sizeof(*pcf), GFP_KERNEL);
291 if (!pcf)
292 return -ENOMEM;
293
294 err = pcf8523_select_capacitance(client, true);
295 if (err < 0)
296 return err;
297
298 err = pcf8523_set_pm(client, 0);
299 if (err < 0)
300 return err;
301
302 pcf->rtc = devm_rtc_device_register(&client->dev, DRIVER_NAME,
303 &pcf8523_rtc_ops, THIS_MODULE);
304 if (IS_ERR(pcf->rtc))
305 return PTR_ERR(pcf->rtc);
306
307 i2c_set_clientdata(client, pcf);
308
309 return 0;
310}
311
312static const struct i2c_device_id pcf8523_id[] = {
313 { "pcf8523", 0 },
314 { }
315};
316MODULE_DEVICE_TABLE(i2c, pcf8523_id);
317
318#ifdef CONFIG_OF
319static const struct of_device_id pcf8523_of_match[] = {
320 { .compatible = "nxp,pcf8523" },
321 { }
322};
323MODULE_DEVICE_TABLE(of, pcf8523_of_match);
324#endif
325
326static struct i2c_driver pcf8523_driver = {
327 .driver = {
328 .name = DRIVER_NAME,
329 .of_match_table = of_match_ptr(pcf8523_of_match),
330 },
331 .probe = pcf8523_probe,
332 .id_table = pcf8523_id,
333};
334module_i2c_driver(pcf8523_driver);
335
336MODULE_AUTHOR("Thierry Reding <thierry.reding@avionic-design.de>");
337MODULE_DESCRIPTION("NXP PCF8523 RTC driver");
338MODULE_LICENSE("GPL v2");
1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * Copyright (C) 2012 Avionic Design GmbH
4 */
5
6#include <linux/bcd.h>
7#include <linux/i2c.h>
8#include <linux/module.h>
9#include <linux/rtc.h>
10#include <linux/of.h>
11
12#define DRIVER_NAME "rtc-pcf8523"
13
14#define REG_CONTROL1 0x00
15#define REG_CONTROL1_CAP_SEL (1 << 7)
16#define REG_CONTROL1_STOP (1 << 5)
17
18#define REG_CONTROL3 0x02
19#define REG_CONTROL3_PM_BLD (1 << 7) /* battery low detection disabled */
20#define REG_CONTROL3_PM_VDD (1 << 6) /* switch-over disabled */
21#define REG_CONTROL3_PM_DSM (1 << 5) /* direct switching mode */
22#define REG_CONTROL3_PM_MASK 0xe0
23#define REG_CONTROL3_BLF (1 << 2) /* battery low bit, read-only */
24
25#define REG_SECONDS 0x03
26#define REG_SECONDS_OS (1 << 7)
27
28#define REG_MINUTES 0x04
29#define REG_HOURS 0x05
30#define REG_DAYS 0x06
31#define REG_WEEKDAYS 0x07
32#define REG_MONTHS 0x08
33#define REG_YEARS 0x09
34
35#define REG_OFFSET 0x0e
36#define REG_OFFSET_MODE BIT(7)
37
38struct pcf8523 {
39 struct rtc_device *rtc;
40};
41
42static int pcf8523_read(struct i2c_client *client, u8 reg, u8 *valuep)
43{
44 struct i2c_msg msgs[2];
45 u8 value = 0;
46 int err;
47
48 msgs[0].addr = client->addr;
49 msgs[0].flags = 0;
50 msgs[0].len = sizeof(reg);
51 msgs[0].buf = ®
52
53 msgs[1].addr = client->addr;
54 msgs[1].flags = I2C_M_RD;
55 msgs[1].len = sizeof(value);
56 msgs[1].buf = &value;
57
58 err = i2c_transfer(client->adapter, msgs, ARRAY_SIZE(msgs));
59 if (err < 0)
60 return err;
61
62 *valuep = value;
63
64 return 0;
65}
66
67static int pcf8523_write(struct i2c_client *client, u8 reg, u8 value)
68{
69 u8 buffer[2] = { reg, value };
70 struct i2c_msg msg;
71 int err;
72
73 msg.addr = client->addr;
74 msg.flags = 0;
75 msg.len = sizeof(buffer);
76 msg.buf = buffer;
77
78 err = i2c_transfer(client->adapter, &msg, 1);
79 if (err < 0)
80 return err;
81
82 return 0;
83}
84
85static int pcf8523_voltage_low(struct i2c_client *client)
86{
87 u8 value;
88 int err;
89
90 err = pcf8523_read(client, REG_CONTROL3, &value);
91 if (err < 0)
92 return err;
93
94 return !!(value & REG_CONTROL3_BLF);
95}
96
97static int pcf8523_load_capacitance(struct i2c_client *client)
98{
99 u32 load;
100 u8 value;
101 int err;
102
103 err = pcf8523_read(client, REG_CONTROL1, &value);
104 if (err < 0)
105 return err;
106
107 load = 12500;
108 of_property_read_u32(client->dev.of_node, "quartz-load-femtofarads",
109 &load);
110
111 switch (load) {
112 default:
113 dev_warn(&client->dev, "Unknown quartz-load-femtofarads value: %d. Assuming 12500",
114 load);
115 /* fall through */
116 case 12500:
117 value |= REG_CONTROL1_CAP_SEL;
118 break;
119 case 7000:
120 value &= ~REG_CONTROL1_CAP_SEL;
121 break;
122 }
123
124 err = pcf8523_write(client, REG_CONTROL1, value);
125
126 return err;
127}
128
129static int pcf8523_set_pm(struct i2c_client *client, u8 pm)
130{
131 u8 value;
132 int err;
133
134 err = pcf8523_read(client, REG_CONTROL3, &value);
135 if (err < 0)
136 return err;
137
138 value = (value & ~REG_CONTROL3_PM_MASK) | pm;
139
140 err = pcf8523_write(client, REG_CONTROL3, value);
141 if (err < 0)
142 return err;
143
144 return 0;
145}
146
147static int pcf8523_stop_rtc(struct i2c_client *client)
148{
149 u8 value;
150 int err;
151
152 err = pcf8523_read(client, REG_CONTROL1, &value);
153 if (err < 0)
154 return err;
155
156 value |= REG_CONTROL1_STOP;
157
158 err = pcf8523_write(client, REG_CONTROL1, value);
159 if (err < 0)
160 return err;
161
162 return 0;
163}
164
165static int pcf8523_start_rtc(struct i2c_client *client)
166{
167 u8 value;
168 int err;
169
170 err = pcf8523_read(client, REG_CONTROL1, &value);
171 if (err < 0)
172 return err;
173
174 value &= ~REG_CONTROL1_STOP;
175
176 err = pcf8523_write(client, REG_CONTROL1, value);
177 if (err < 0)
178 return err;
179
180 return 0;
181}
182
183static int pcf8523_rtc_read_time(struct device *dev, struct rtc_time *tm)
184{
185 struct i2c_client *client = to_i2c_client(dev);
186 u8 start = REG_SECONDS, regs[7];
187 struct i2c_msg msgs[2];
188 int err;
189
190 err = pcf8523_voltage_low(client);
191 if (err < 0) {
192 return err;
193 } else if (err > 0) {
194 dev_err(dev, "low voltage detected, time is unreliable\n");
195 return -EINVAL;
196 }
197
198 msgs[0].addr = client->addr;
199 msgs[0].flags = 0;
200 msgs[0].len = 1;
201 msgs[0].buf = &start;
202
203 msgs[1].addr = client->addr;
204 msgs[1].flags = I2C_M_RD;
205 msgs[1].len = sizeof(regs);
206 msgs[1].buf = regs;
207
208 err = i2c_transfer(client->adapter, msgs, ARRAY_SIZE(msgs));
209 if (err < 0)
210 return err;
211
212 if (regs[0] & REG_SECONDS_OS)
213 return -EINVAL;
214
215 tm->tm_sec = bcd2bin(regs[0] & 0x7f);
216 tm->tm_min = bcd2bin(regs[1] & 0x7f);
217 tm->tm_hour = bcd2bin(regs[2] & 0x3f);
218 tm->tm_mday = bcd2bin(regs[3] & 0x3f);
219 tm->tm_wday = regs[4] & 0x7;
220 tm->tm_mon = bcd2bin(regs[5] & 0x1f) - 1;
221 tm->tm_year = bcd2bin(regs[6]) + 100;
222
223 return 0;
224}
225
226static int pcf8523_rtc_set_time(struct device *dev, struct rtc_time *tm)
227{
228 struct i2c_client *client = to_i2c_client(dev);
229 struct i2c_msg msg;
230 u8 regs[8];
231 int err;
232
233 /*
234 * The hardware can only store values between 0 and 99 in it's YEAR
235 * register (with 99 overflowing to 0 on increment).
236 * After 2100-02-28 we could start interpreting the year to be in the
237 * interval [2100, 2199], but there is no path to switch in a smooth way
238 * because the chip handles YEAR=0x00 (and the out-of-spec
239 * YEAR=0xa0) as a leap year, but 2100 isn't.
240 */
241 if (tm->tm_year < 100 || tm->tm_year >= 200)
242 return -EINVAL;
243
244 err = pcf8523_stop_rtc(client);
245 if (err < 0)
246 return err;
247
248 regs[0] = REG_SECONDS;
249 /* This will purposely overwrite REG_SECONDS_OS */
250 regs[1] = bin2bcd(tm->tm_sec);
251 regs[2] = bin2bcd(tm->tm_min);
252 regs[3] = bin2bcd(tm->tm_hour);
253 regs[4] = bin2bcd(tm->tm_mday);
254 regs[5] = tm->tm_wday;
255 regs[6] = bin2bcd(tm->tm_mon + 1);
256 regs[7] = bin2bcd(tm->tm_year - 100);
257
258 msg.addr = client->addr;
259 msg.flags = 0;
260 msg.len = sizeof(regs);
261 msg.buf = regs;
262
263 err = i2c_transfer(client->adapter, &msg, 1);
264 if (err < 0) {
265 /*
266 * If the time cannot be set, restart the RTC anyway. Note
267 * that errors are ignored if the RTC cannot be started so
268 * that we have a chance to propagate the original error.
269 */
270 pcf8523_start_rtc(client);
271 return err;
272 }
273
274 return pcf8523_start_rtc(client);
275}
276
277#ifdef CONFIG_RTC_INTF_DEV
278static int pcf8523_rtc_ioctl(struct device *dev, unsigned int cmd,
279 unsigned long arg)
280{
281 struct i2c_client *client = to_i2c_client(dev);
282 int ret;
283
284 switch (cmd) {
285 case RTC_VL_READ:
286 ret = pcf8523_voltage_low(client);
287 if (ret < 0)
288 return ret;
289
290 if (copy_to_user((void __user *)arg, &ret, sizeof(int)))
291 return -EFAULT;
292
293 return 0;
294 default:
295 return -ENOIOCTLCMD;
296 }
297}
298#else
299#define pcf8523_rtc_ioctl NULL
300#endif
301
302static int pcf8523_rtc_read_offset(struct device *dev, long *offset)
303{
304 struct i2c_client *client = to_i2c_client(dev);
305 int err;
306 u8 value;
307 s8 val;
308
309 err = pcf8523_read(client, REG_OFFSET, &value);
310 if (err < 0)
311 return err;
312
313 /* sign extend the 7-bit offset value */
314 val = value << 1;
315 *offset = (value & REG_OFFSET_MODE ? 4069 : 4340) * (val >> 1);
316
317 return 0;
318}
319
320static int pcf8523_rtc_set_offset(struct device *dev, long offset)
321{
322 struct i2c_client *client = to_i2c_client(dev);
323 long reg_m0, reg_m1;
324 u8 value;
325
326 reg_m0 = clamp(DIV_ROUND_CLOSEST(offset, 4340), -64L, 63L);
327 reg_m1 = clamp(DIV_ROUND_CLOSEST(offset, 4069), -64L, 63L);
328
329 if (abs(reg_m0 * 4340 - offset) < abs(reg_m1 * 4069 - offset))
330 value = reg_m0 & 0x7f;
331 else
332 value = (reg_m1 & 0x7f) | REG_OFFSET_MODE;
333
334 return pcf8523_write(client, REG_OFFSET, value);
335}
336
337static const struct rtc_class_ops pcf8523_rtc_ops = {
338 .read_time = pcf8523_rtc_read_time,
339 .set_time = pcf8523_rtc_set_time,
340 .ioctl = pcf8523_rtc_ioctl,
341 .read_offset = pcf8523_rtc_read_offset,
342 .set_offset = pcf8523_rtc_set_offset,
343};
344
345static int pcf8523_probe(struct i2c_client *client,
346 const struct i2c_device_id *id)
347{
348 struct pcf8523 *pcf;
349 int err;
350
351 if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C))
352 return -ENODEV;
353
354 pcf = devm_kzalloc(&client->dev, sizeof(*pcf), GFP_KERNEL);
355 if (!pcf)
356 return -ENOMEM;
357
358 err = pcf8523_load_capacitance(client);
359 if (err < 0)
360 dev_warn(&client->dev, "failed to set xtal load capacitance: %d",
361 err);
362
363 err = pcf8523_set_pm(client, 0);
364 if (err < 0)
365 return err;
366
367 pcf->rtc = devm_rtc_device_register(&client->dev, DRIVER_NAME,
368 &pcf8523_rtc_ops, THIS_MODULE);
369 if (IS_ERR(pcf->rtc))
370 return PTR_ERR(pcf->rtc);
371
372 i2c_set_clientdata(client, pcf);
373
374 return 0;
375}
376
377static const struct i2c_device_id pcf8523_id[] = {
378 { "pcf8523", 0 },
379 { }
380};
381MODULE_DEVICE_TABLE(i2c, pcf8523_id);
382
383#ifdef CONFIG_OF
384static const struct of_device_id pcf8523_of_match[] = {
385 { .compatible = "nxp,pcf8523" },
386 { .compatible = "microcrystal,rv8523" },
387 { }
388};
389MODULE_DEVICE_TABLE(of, pcf8523_of_match);
390#endif
391
392static struct i2c_driver pcf8523_driver = {
393 .driver = {
394 .name = DRIVER_NAME,
395 .of_match_table = of_match_ptr(pcf8523_of_match),
396 },
397 .probe = pcf8523_probe,
398 .id_table = pcf8523_id,
399};
400module_i2c_driver(pcf8523_driver);
401
402MODULE_AUTHOR("Thierry Reding <thierry.reding@avionic-design.de>");
403MODULE_DESCRIPTION("NXP PCF8523 RTC driver");
404MODULE_LICENSE("GPL v2");