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f803f0d0 TR |
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 | ||
27 | #define REG_SECONDS 0x03 | |
28 | #define REG_SECONDS_OS (1 << 7) | |
29 | ||
30 | #define REG_MINUTES 0x04 | |
31 | #define REG_HOURS 0x05 | |
32 | #define REG_DAYS 0x06 | |
33 | #define REG_WEEKDAYS 0x07 | |
34 | #define REG_MONTHS 0x08 | |
35 | #define REG_YEARS 0x09 | |
36 | ||
37 | struct pcf8523 { | |
38 | struct rtc_device *rtc; | |
39 | }; | |
40 | ||
41 | static int pcf8523_read(struct i2c_client *client, u8 reg, u8 *valuep) | |
42 | { | |
43 | struct i2c_msg msgs[2]; | |
44 | u8 value = 0; | |
45 | int err; | |
46 | ||
47 | msgs[0].addr = client->addr; | |
48 | msgs[0].flags = 0; | |
49 | msgs[0].len = sizeof(reg); | |
50 | msgs[0].buf = ® | |
51 | ||
52 | msgs[1].addr = client->addr; | |
53 | msgs[1].flags = I2C_M_RD; | |
54 | msgs[1].len = sizeof(value); | |
55 | msgs[1].buf = &value; | |
56 | ||
57 | err = i2c_transfer(client->adapter, msgs, ARRAY_SIZE(msgs)); | |
58 | if (err < 0) | |
59 | return err; | |
60 | ||
61 | *valuep = value; | |
62 | ||
63 | return 0; | |
64 | } | |
65 | ||
66 | static int pcf8523_write(struct i2c_client *client, u8 reg, u8 value) | |
67 | { | |
68 | u8 buffer[2] = { reg, value }; | |
69 | struct i2c_msg msg; | |
70 | int err; | |
71 | ||
72 | msg.addr = client->addr; | |
73 | msg.flags = 0; | |
74 | msg.len = sizeof(buffer); | |
75 | msg.buf = buffer; | |
76 | ||
77 | err = i2c_transfer(client->adapter, &msg, 1); | |
78 | if (err < 0) | |
79 | return err; | |
80 | ||
81 | return 0; | |
82 | } | |
83 | ||
84 | static int pcf8523_select_capacitance(struct i2c_client *client, bool high) | |
85 | { | |
86 | u8 value; | |
87 | int err; | |
88 | ||
89 | err = pcf8523_read(client, REG_CONTROL1, &value); | |
90 | if (err < 0) | |
91 | return err; | |
92 | ||
93 | if (!high) | |
94 | value &= ~REG_CONTROL1_CAP_SEL; | |
95 | else | |
96 | value |= REG_CONTROL1_CAP_SEL; | |
97 | ||
98 | err = pcf8523_write(client, REG_CONTROL1, value); | |
99 | if (err < 0) | |
100 | return err; | |
101 | ||
102 | return err; | |
103 | } | |
104 | ||
105 | static int pcf8523_set_pm(struct i2c_client *client, u8 pm) | |
106 | { | |
107 | u8 value; | |
108 | int err; | |
109 | ||
110 | err = pcf8523_read(client, REG_CONTROL3, &value); | |
111 | if (err < 0) | |
112 | return err; | |
113 | ||
114 | value = (value & ~REG_CONTROL3_PM_MASK) | pm; | |
115 | ||
116 | err = pcf8523_write(client, REG_CONTROL3, value); | |
117 | if (err < 0) | |
118 | return err; | |
119 | ||
120 | return 0; | |
121 | } | |
122 | ||
123 | static int pcf8523_stop_rtc(struct i2c_client *client) | |
124 | { | |
125 | u8 value; | |
126 | int err; | |
127 | ||
128 | err = pcf8523_read(client, REG_CONTROL1, &value); | |
129 | if (err < 0) | |
130 | return err; | |
131 | ||
132 | value |= REG_CONTROL1_STOP; | |
133 | ||
134 | err = pcf8523_write(client, REG_CONTROL1, value); | |
135 | if (err < 0) | |
136 | return err; | |
137 | ||
138 | return 0; | |
139 | } | |
140 | ||
141 | static int pcf8523_start_rtc(struct i2c_client *client) | |
142 | { | |
143 | u8 value; | |
144 | int err; | |
145 | ||
146 | err = pcf8523_read(client, REG_CONTROL1, &value); | |
147 | if (err < 0) | |
148 | return err; | |
149 | ||
150 | value &= ~REG_CONTROL1_STOP; | |
151 | ||
152 | err = pcf8523_write(client, REG_CONTROL1, value); | |
153 | if (err < 0) | |
154 | return err; | |
155 | ||
156 | return 0; | |
157 | } | |
158 | ||
159 | static int pcf8523_rtc_read_time(struct device *dev, struct rtc_time *tm) | |
160 | { | |
161 | struct i2c_client *client = to_i2c_client(dev); | |
162 | u8 start = REG_SECONDS, regs[7]; | |
163 | struct i2c_msg msgs[2]; | |
164 | int err; | |
165 | ||
166 | msgs[0].addr = client->addr; | |
167 | msgs[0].flags = 0; | |
168 | msgs[0].len = 1; | |
169 | msgs[0].buf = &start; | |
170 | ||
171 | msgs[1].addr = client->addr; | |
172 | msgs[1].flags = I2C_M_RD; | |
173 | msgs[1].len = sizeof(regs); | |
174 | msgs[1].buf = regs; | |
175 | ||
176 | err = i2c_transfer(client->adapter, msgs, ARRAY_SIZE(msgs)); | |
177 | if (err < 0) | |
178 | return err; | |
179 | ||
180 | if (regs[0] & REG_SECONDS_OS) { | |
181 | /* | |
182 | * If the oscillator was stopped, try to clear the flag. Upon | |
183 | * power-up the flag is always set, but if we cannot clear it | |
184 | * the oscillator isn't running properly for some reason. The | |
185 | * sensible thing therefore is to return an error, signalling | |
186 | * that the clock cannot be assumed to be correct. | |
187 | */ | |
188 | ||
189 | regs[0] &= ~REG_SECONDS_OS; | |
190 | ||
191 | err = pcf8523_write(client, REG_SECONDS, regs[0]); | |
192 | if (err < 0) | |
193 | return err; | |
194 | ||
195 | err = pcf8523_read(client, REG_SECONDS, ®s[0]); | |
196 | if (err < 0) | |
197 | return err; | |
198 | ||
199 | if (regs[0] & REG_SECONDS_OS) | |
200 | return -EAGAIN; | |
201 | } | |
202 | ||
203 | tm->tm_sec = bcd2bin(regs[0] & 0x7f); | |
204 | tm->tm_min = bcd2bin(regs[1] & 0x7f); | |
205 | tm->tm_hour = bcd2bin(regs[2] & 0x3f); | |
206 | tm->tm_mday = bcd2bin(regs[3] & 0x3f); | |
207 | tm->tm_wday = regs[4] & 0x7; | |
208 | tm->tm_mon = bcd2bin(regs[5] & 0x1f); | |
209 | tm->tm_year = bcd2bin(regs[6]) + 100; | |
210 | ||
211 | return rtc_valid_tm(tm); | |
212 | } | |
213 | ||
214 | static int pcf8523_rtc_set_time(struct device *dev, struct rtc_time *tm) | |
215 | { | |
216 | struct i2c_client *client = to_i2c_client(dev); | |
217 | struct i2c_msg msg; | |
218 | u8 regs[8]; | |
219 | int err; | |
220 | ||
221 | err = pcf8523_stop_rtc(client); | |
222 | if (err < 0) | |
223 | return err; | |
224 | ||
225 | regs[0] = REG_SECONDS; | |
226 | regs[1] = bin2bcd(tm->tm_sec); | |
227 | regs[2] = bin2bcd(tm->tm_min); | |
228 | regs[3] = bin2bcd(tm->tm_hour); | |
229 | regs[4] = bin2bcd(tm->tm_mday); | |
230 | regs[5] = tm->tm_wday; | |
231 | regs[6] = bin2bcd(tm->tm_mon); | |
232 | regs[7] = bin2bcd(tm->tm_year - 100); | |
233 | ||
234 | msg.addr = client->addr; | |
235 | msg.flags = 0; | |
236 | msg.len = sizeof(regs); | |
237 | msg.buf = regs; | |
238 | ||
239 | err = i2c_transfer(client->adapter, &msg, 1); | |
240 | if (err < 0) { | |
241 | /* | |
242 | * If the time cannot be set, restart the RTC anyway. Note | |
243 | * that errors are ignored if the RTC cannot be started so | |
244 | * that we have a chance to propagate the original error. | |
245 | */ | |
246 | pcf8523_start_rtc(client); | |
247 | return err; | |
248 | } | |
249 | ||
250 | return pcf8523_start_rtc(client); | |
251 | } | |
252 | ||
253 | static const struct rtc_class_ops pcf8523_rtc_ops = { | |
254 | .read_time = pcf8523_rtc_read_time, | |
255 | .set_time = pcf8523_rtc_set_time, | |
256 | }; | |
257 | ||
258 | static int pcf8523_probe(struct i2c_client *client, | |
259 | const struct i2c_device_id *id) | |
260 | { | |
261 | struct pcf8523 *pcf; | |
262 | int err; | |
263 | ||
264 | if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C)) | |
265 | return -ENODEV; | |
266 | ||
267 | pcf = devm_kzalloc(&client->dev, sizeof(*pcf), GFP_KERNEL); | |
268 | if (!pcf) | |
269 | return -ENOMEM; | |
270 | ||
271 | err = pcf8523_select_capacitance(client, true); | |
272 | if (err < 0) | |
273 | return err; | |
274 | ||
275 | err = pcf8523_set_pm(client, 0); | |
276 | if (err < 0) | |
277 | return err; | |
278 | ||
279 | pcf->rtc = rtc_device_register(DRIVER_NAME, &client->dev, | |
280 | &pcf8523_rtc_ops, THIS_MODULE); | |
281 | if (IS_ERR(pcf->rtc)) | |
282 | return PTR_ERR(pcf->rtc); | |
283 | ||
284 | i2c_set_clientdata(client, pcf); | |
285 | ||
286 | return 0; | |
287 | } | |
288 | ||
289 | static int pcf8523_remove(struct i2c_client *client) | |
290 | { | |
291 | struct pcf8523 *pcf = i2c_get_clientdata(client); | |
292 | ||
293 | rtc_device_unregister(pcf->rtc); | |
294 | ||
295 | return 0; | |
296 | } | |
297 | ||
298 | static const struct i2c_device_id pcf8523_id[] = { | |
299 | { "pcf8523", 0 }, | |
300 | { } | |
301 | }; | |
302 | MODULE_DEVICE_TABLE(i2c, pcf8523_id); | |
303 | ||
304 | #ifdef CONFIG_OF | |
305 | static const struct of_device_id pcf8523_of_match[] = { | |
306 | { .compatible = "nxp,pcf8523" }, | |
307 | { } | |
308 | }; | |
309 | MODULE_DEVICE_TABLE(of, pcf8523_of_match); | |
310 | #endif | |
311 | ||
312 | static struct i2c_driver pcf8523_driver = { | |
313 | .driver = { | |
314 | .name = DRIVER_NAME, | |
315 | .owner = THIS_MODULE, | |
316 | .of_match_table = of_match_ptr(pcf8523_of_match), | |
317 | }, | |
318 | .probe = pcf8523_probe, | |
319 | .remove = pcf8523_remove, | |
320 | .id_table = pcf8523_id, | |
321 | }; | |
322 | module_i2c_driver(pcf8523_driver); | |
323 | ||
324 | MODULE_AUTHOR("Thierry Reding <thierry.reding@avionic-design.de>"); | |
325 | MODULE_DESCRIPTION("NXP PCF8523 RTC driver"); | |
326 | MODULE_LICENSE("GPL v2"); |