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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)
23#define REG_CONTROL3_PM_VDD (1 << 6)
24#define REG_CONTROL3_PM_DSM (1 << 5)
25#define REG_CONTROL3_PM_MASK 0xe0
26#define REG_CONTROL3_BLF (1 << 2)
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
38#define REG_OFFSET 0x0e
39#define REG_OFFSET_MODE BIT(7)
40
41struct pcf8523 {
42 struct rtc_device *rtc;
43};
44
45static int pcf8523_read(struct i2c_client *client, u8 reg, u8 *valuep)
46{
47 struct i2c_msg msgs[2];
48 u8 value = 0;
49 int err;
50
51 msgs[0].addr = client->addr;
52 msgs[0].flags = 0;
53 msgs[0].len = sizeof(reg);
54 msgs[0].buf = ®
55
56 msgs[1].addr = client->addr;
57 msgs[1].flags = I2C_M_RD;
58 msgs[1].len = sizeof(value);
59 msgs[1].buf = &value;
60
61 err = i2c_transfer(client->adapter, msgs, ARRAY_SIZE(msgs));
62 if (err < 0)
63 return err;
64
65 *valuep = value;
66
67 return 0;
68}
69
70static int pcf8523_write(struct i2c_client *client, u8 reg, u8 value)
71{
72 u8 buffer[2] = { reg, value };
73 struct i2c_msg msg;
74 int err;
75
76 msg.addr = client->addr;
77 msg.flags = 0;
78 msg.len = sizeof(buffer);
79 msg.buf = buffer;
80
81 err = i2c_transfer(client->adapter, &msg, 1);
82 if (err < 0)
83 return err;
84
85 return 0;
86}
87
88static int pcf8523_voltage_low(struct i2c_client *client)
89{
90 u8 value;
91 int err;
92
93 err = pcf8523_read(client, REG_CONTROL3, &value);
94 if (err < 0)
95 return err;
96
97 return !!(value & REG_CONTROL3_BLF);
98}
99
100static int pcf8523_select_capacitance(struct i2c_client *client, bool high)
101{
102 u8 value;
103 int err;
104
105 err = pcf8523_read(client, REG_CONTROL1, &value);
106 if (err < 0)
107 return err;
108
109 if (!high)
110 value &= ~REG_CONTROL1_CAP_SEL;
111 else
112 value |= REG_CONTROL1_CAP_SEL;
113
114 err = pcf8523_write(client, REG_CONTROL1, value);
115 if (err < 0)
116 return err;
117
118 return err;
119}
120
121static int pcf8523_set_pm(struct i2c_client *client, u8 pm)
122{
123 u8 value;
124 int err;
125
126 err = pcf8523_read(client, REG_CONTROL3, &value);
127 if (err < 0)
128 return err;
129
130 value = (value & ~REG_CONTROL3_PM_MASK) | pm;
131
132 err = pcf8523_write(client, REG_CONTROL3, value);
133 if (err < 0)
134 return err;
135
136 return 0;
137}
138
139static int pcf8523_stop_rtc(struct i2c_client *client)
140{
141 u8 value;
142 int err;
143
144 err = pcf8523_read(client, REG_CONTROL1, &value);
145 if (err < 0)
146 return err;
147
148 value |= REG_CONTROL1_STOP;
149
150 err = pcf8523_write(client, REG_CONTROL1, value);
151 if (err < 0)
152 return err;
153
154 return 0;
155}
156
157static int pcf8523_start_rtc(struct i2c_client *client)
158{
159 u8 value;
160 int err;
161
162 err = pcf8523_read(client, REG_CONTROL1, &value);
163 if (err < 0)
164 return err;
165
166 value &= ~REG_CONTROL1_STOP;
167
168 err = pcf8523_write(client, REG_CONTROL1, value);
169 if (err < 0)
170 return err;
171
172 return 0;
173}
174
175static int pcf8523_rtc_read_time(struct device *dev, struct rtc_time *tm)
176{
177 struct i2c_client *client = to_i2c_client(dev);
178 u8 start = REG_SECONDS, regs[7];
179 struct i2c_msg msgs[2];
180 int err;
181
182 err = pcf8523_voltage_low(client);
183 if (err < 0) {
184 return err;
185 } else if (err > 0) {
186 dev_err(dev, "low voltage detected, time is unreliable\n");
187 return -EINVAL;
188 }
189
190 msgs[0].addr = client->addr;
191 msgs[0].flags = 0;
192 msgs[0].len = 1;
193 msgs[0].buf = &start;
194
195 msgs[1].addr = client->addr;
196 msgs[1].flags = I2C_M_RD;
197 msgs[1].len = sizeof(regs);
198 msgs[1].buf = regs;
199
200 err = i2c_transfer(client->adapter, msgs, ARRAY_SIZE(msgs));
201 if (err < 0)
202 return err;
203
204 if (regs[0] & REG_SECONDS_OS)
205 return -EINVAL;
206
207 tm->tm_sec = bcd2bin(regs[0] & 0x7f);
208 tm->tm_min = bcd2bin(regs[1] & 0x7f);
209 tm->tm_hour = bcd2bin(regs[2] & 0x3f);
210 tm->tm_mday = bcd2bin(regs[3] & 0x3f);
211 tm->tm_wday = regs[4] & 0x7;
212 tm->tm_mon = bcd2bin(regs[5] & 0x1f) - 1;
213 tm->tm_year = bcd2bin(regs[6]) + 100;
214
215 return 0;
216}
217
218static int pcf8523_rtc_set_time(struct device *dev, struct rtc_time *tm)
219{
220 struct i2c_client *client = to_i2c_client(dev);
221 struct i2c_msg msg;
222 u8 regs[8];
223 int err;
224
225
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227
228
229
230
231
232
233 if (tm->tm_year < 100 || tm->tm_year >= 200)
234 return -EINVAL;
235
236 err = pcf8523_stop_rtc(client);
237 if (err < 0)
238 return err;
239
240 regs[0] = REG_SECONDS;
241
242 regs[1] = bin2bcd(tm->tm_sec);
243 regs[2] = bin2bcd(tm->tm_min);
244 regs[3] = bin2bcd(tm->tm_hour);
245 regs[4] = bin2bcd(tm->tm_mday);
246 regs[5] = tm->tm_wday;
247 regs[6] = bin2bcd(tm->tm_mon + 1);
248 regs[7] = bin2bcd(tm->tm_year - 100);
249
250 msg.addr = client->addr;
251 msg.flags = 0;
252 msg.len = sizeof(regs);
253 msg.buf = regs;
254
255 err = i2c_transfer(client->adapter, &msg, 1);
256 if (err < 0) {
257
258
259
260
261
262 pcf8523_start_rtc(client);
263 return err;
264 }
265
266 return pcf8523_start_rtc(client);
267}
268
269#ifdef CONFIG_RTC_INTF_DEV
270static int pcf8523_rtc_ioctl(struct device *dev, unsigned int cmd,
271 unsigned long arg)
272{
273 struct i2c_client *client = to_i2c_client(dev);
274 int ret;
275
276 switch (cmd) {
277 case RTC_VL_READ:
278 ret = pcf8523_voltage_low(client);
279 if (ret < 0)
280 return ret;
281
282 if (copy_to_user((void __user *)arg, &ret, sizeof(int)))
283 return -EFAULT;
284
285 return 0;
286 default:
287 return -ENOIOCTLCMD;
288 }
289}
290#else
291#define pcf8523_rtc_ioctl NULL
292#endif
293
294static int pcf8523_rtc_read_offset(struct device *dev, long *offset)
295{
296 struct i2c_client *client = to_i2c_client(dev);
297 int err;
298 u8 value;
299 s8 val;
300
301 err = pcf8523_read(client, REG_OFFSET, &value);
302 if (err < 0)
303 return err;
304
305
306 val = value << 1;
307 *offset = (value & REG_OFFSET_MODE ? 4069 : 4340) * (val >> 1);
308
309 return 0;
310}
311
312static int pcf8523_rtc_set_offset(struct device *dev, long offset)
313{
314 struct i2c_client *client = to_i2c_client(dev);
315 long reg_m0, reg_m1;
316 u8 value;
317
318 reg_m0 = clamp(DIV_ROUND_CLOSEST(offset, 4340), -64L, 63L);
319 reg_m1 = clamp(DIV_ROUND_CLOSEST(offset, 4069), -64L, 63L);
320
321 if (abs(reg_m0 * 4340 - offset) < abs(reg_m1 * 4069 - offset))
322 value = reg_m0 & 0x7f;
323 else
324 value = (reg_m1 & 0x7f) | REG_OFFSET_MODE;
325
326 return pcf8523_write(client, REG_OFFSET, value);
327}
328
329static const struct rtc_class_ops pcf8523_rtc_ops = {
330 .read_time = pcf8523_rtc_read_time,
331 .set_time = pcf8523_rtc_set_time,
332 .ioctl = pcf8523_rtc_ioctl,
333 .read_offset = pcf8523_rtc_read_offset,
334 .set_offset = pcf8523_rtc_set_offset,
335};
336
337static int pcf8523_probe(struct i2c_client *client,
338 const struct i2c_device_id *id)
339{
340 struct pcf8523 *pcf;
341 int err;
342
343 if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C))
344 return -ENODEV;
345
346 pcf = devm_kzalloc(&client->dev, sizeof(*pcf), GFP_KERNEL);
347 if (!pcf)
348 return -ENOMEM;
349
350 err = pcf8523_select_capacitance(client, true);
351 if (err < 0)
352 return err;
353
354 err = pcf8523_set_pm(client, 0);
355 if (err < 0)
356 return err;
357
358 pcf->rtc = devm_rtc_device_register(&client->dev, DRIVER_NAME,
359 &pcf8523_rtc_ops, THIS_MODULE);
360 if (IS_ERR(pcf->rtc))
361 return PTR_ERR(pcf->rtc);
362
363 i2c_set_clientdata(client, pcf);
364
365 return 0;
366}
367
368static const struct i2c_device_id pcf8523_id[] = {
369 { "pcf8523", 0 },
370 { }
371};
372MODULE_DEVICE_TABLE(i2c, pcf8523_id);
373
374#ifdef CONFIG_OF
375static const struct of_device_id pcf8523_of_match[] = {
376 { .compatible = "nxp,pcf8523" },
377 { }
378};
379MODULE_DEVICE_TABLE(of, pcf8523_of_match);
380#endif
381
382static struct i2c_driver pcf8523_driver = {
383 .driver = {
384 .name = DRIVER_NAME,
385 .of_match_table = of_match_ptr(pcf8523_of_match),
386 },
387 .probe = pcf8523_probe,
388 .id_table = pcf8523_id,
389};
390module_i2c_driver(pcf8523_driver);
391
392MODULE_AUTHOR("Thierry Reding <thierry.reding@avionic-design.de>");
393MODULE_DESCRIPTION("NXP PCF8523 RTC driver");
394MODULE_LICENSE("GPL v2");
395
