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d2912cb1 | 1 | // SPDX-License-Identifier: GPL-2.0-only |
f803f0d0 TR |
2 | /* |
3 | * Copyright (C) 2012 Avionic Design GmbH | |
f803f0d0 TR |
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 | |
f32bc70d | 23 | #define REG_CONTROL3_BLF (1 << 2) /* battery low bit, read-only */ |
f803f0d0 TR |
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 | ||
bc3bee02 RK |
35 | #define REG_OFFSET 0x0e |
36 | #define REG_OFFSET_MODE BIT(7) | |
37 | ||
f803f0d0 TR |
38 | struct pcf8523 { |
39 | struct rtc_device *rtc; | |
40 | }; | |
41 | ||
42 | static 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 | ||
67 | static 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 | ||
ecb4a353 BS |
85 | static 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 | ||
189927e7 | 97 | static int pcf8523_load_capacitance(struct i2c_client *client) |
f803f0d0 | 98 | { |
189927e7 | 99 | u32 load; |
f803f0d0 TR |
100 | u8 value; |
101 | int err; | |
102 | ||
103 | err = pcf8523_read(client, REG_CONTROL1, &value); | |
104 | if (err < 0) | |
105 | return err; | |
106 | ||
189927e7 SR |
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: | |
f803f0d0 | 117 | value |= REG_CONTROL1_CAP_SEL; |
189927e7 SR |
118 | break; |
119 | case 7000: | |
120 | value &= ~REG_CONTROL1_CAP_SEL; | |
121 | break; | |
122 | } | |
f803f0d0 TR |
123 | |
124 | err = pcf8523_write(client, REG_CONTROL1, value); | |
f803f0d0 TR |
125 | |
126 | return err; | |
127 | } | |
128 | ||
129 | static 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 | ||
147 | static 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 | ||
165 | static 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 | ||
183 | static 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 | ||
ecb4a353 BS |
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 | ||
f803f0d0 TR |
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 | ||
ede44c90 AB |
212 | if (regs[0] & REG_SECONDS_OS) |
213 | return -EINVAL; | |
f803f0d0 TR |
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; | |
35738392 | 220 | tm->tm_mon = bcd2bin(regs[5] & 0x1f) - 1; |
f803f0d0 TR |
221 | tm->tm_year = bcd2bin(regs[6]) + 100; |
222 | ||
22652ba7 | 223 | return 0; |
f803f0d0 TR |
224 | } |
225 | ||
226 | static 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 | ||
fbbf53f7 UKK |
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 | ||
f803f0d0 TR |
244 | err = pcf8523_stop_rtc(client); |
245 | if (err < 0) | |
246 | return err; | |
247 | ||
248 | regs[0] = REG_SECONDS; | |
ede44c90 | 249 | /* This will purposely overwrite REG_SECONDS_OS */ |
f803f0d0 TR |
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; | |
35738392 | 255 | regs[6] = bin2bcd(tm->tm_mon + 1); |
f803f0d0 TR |
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 | ||
f32bc70d JN |
277 | #ifdef CONFIG_RTC_INTF_DEV |
278 | static int pcf8523_rtc_ioctl(struct device *dev, unsigned int cmd, | |
279 | unsigned long arg) | |
280 | { | |
281 | struct i2c_client *client = to_i2c_client(dev); | |
ecb4a353 | 282 | int ret; |
f32bc70d JN |
283 | |
284 | switch (cmd) { | |
285 | case RTC_VL_READ: | |
ecb4a353 BS |
286 | ret = pcf8523_voltage_low(client); |
287 | if (ret < 0) | |
288 | return ret; | |
f32bc70d JN |
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 | ||
bc3bee02 RK |
302 | static 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 | ||
320 | static 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 | ||
f803f0d0 TR |
337 | static const struct rtc_class_ops pcf8523_rtc_ops = { |
338 | .read_time = pcf8523_rtc_read_time, | |
339 | .set_time = pcf8523_rtc_set_time, | |
f32bc70d | 340 | .ioctl = pcf8523_rtc_ioctl, |
bc3bee02 RK |
341 | .read_offset = pcf8523_rtc_read_offset, |
342 | .set_offset = pcf8523_rtc_set_offset, | |
f803f0d0 TR |
343 | }; |
344 | ||
345 | static 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 | ||
189927e7 | 358 | err = pcf8523_load_capacitance(client); |
f803f0d0 | 359 | if (err < 0) |
189927e7 SR |
360 | dev_warn(&client->dev, "failed to set xtal load capacitance: %d", |
361 | err); | |
f803f0d0 TR |
362 | |
363 | err = pcf8523_set_pm(client, 0); | |
364 | if (err < 0) | |
365 | return err; | |
366 | ||
288031bf | 367 | pcf->rtc = devm_rtc_device_register(&client->dev, DRIVER_NAME, |
f803f0d0 TR |
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 | ||
f803f0d0 TR |
377 | static const struct i2c_device_id pcf8523_id[] = { |
378 | { "pcf8523", 0 }, | |
379 | { } | |
380 | }; | |
381 | MODULE_DEVICE_TABLE(i2c, pcf8523_id); | |
382 | ||
383 | #ifdef CONFIG_OF | |
384 | static const struct of_device_id pcf8523_of_match[] = { | |
385 | { .compatible = "nxp,pcf8523" }, | |
7c617e0c | 386 | { .compatible = "microcrystal,rv8523" }, |
f803f0d0 TR |
387 | { } |
388 | }; | |
389 | MODULE_DEVICE_TABLE(of, pcf8523_of_match); | |
390 | #endif | |
391 | ||
392 | static struct i2c_driver pcf8523_driver = { | |
393 | .driver = { | |
394 | .name = DRIVER_NAME, | |
f803f0d0 TR |
395 | .of_match_table = of_match_ptr(pcf8523_of_match), |
396 | }, | |
397 | .probe = pcf8523_probe, | |
f803f0d0 TR |
398 | .id_table = pcf8523_id, |
399 | }; | |
400 | module_i2c_driver(pcf8523_driver); | |
401 | ||
402 | MODULE_AUTHOR("Thierry Reding <thierry.reding@avionic-design.de>"); | |
403 | MODULE_DESCRIPTION("NXP PCF8523 RTC driver"); | |
404 | MODULE_LICENSE("GPL v2"); |