1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * An I2C driver for the Epson RX8581 RTC
4 *
5 * Author: Martyn Welch <martyn.welch@ge.com>
6 * Copyright 2008 GE Intelligent Platforms Embedded Systems, Inc.
7 *
8 * Based on: rtc-pcf8563.c (An I2C driver for the Philips PCF8563 RTC)
9 * Copyright 2005-06 Tower Technologies
10 */
11
12#include <linux/module.h>
13#include <linux/i2c.h>
14#include <linux/bcd.h>
15#include <linux/of.h>
16#include <linux/regmap.h>
17#include <linux/rtc.h>
18#include <linux/log2.h>
19
20#define RX8581_REG_SC 0x00 /* Second in BCD */
21#define RX8581_REG_MN 0x01 /* Minute in BCD */
22#define RX8581_REG_HR 0x02 /* Hour in BCD */
23#define RX8581_REG_DW 0x03 /* Day of Week */
24#define RX8581_REG_DM 0x04 /* Day of Month in BCD */
25#define RX8581_REG_MO 0x05 /* Month in BCD */
26#define RX8581_REG_YR 0x06 /* Year in BCD */
27#define RX8581_REG_RAM 0x07 /* RAM */
28#define RX8581_REG_AMN 0x08 /* Alarm Min in BCD*/
29#define RX8581_REG_AHR 0x09 /* Alarm Hour in BCD */
30#define RX8581_REG_ADM 0x0A
31#define RX8581_REG_ADW 0x0A
32#define RX8581_REG_TMR0 0x0B
33#define RX8581_REG_TMR1 0x0C
34#define RX8581_REG_EXT 0x0D /* Extension Register */
35#define RX8581_REG_FLAG 0x0E /* Flag Register */
36#define RX8581_REG_CTRL 0x0F /* Control Register */
37
38
39/* Flag Register bit definitions */
40#define RX8581_FLAG_UF 0x20 /* Update */
41#define RX8581_FLAG_TF 0x10 /* Timer */
42#define RX8581_FLAG_AF 0x08 /* Alarm */
43#define RX8581_FLAG_VLF 0x02 /* Voltage Low */
44
45/* Control Register bit definitions */
46#define RX8581_CTRL_UIE 0x20 /* Update Interrupt Enable */
47#define RX8581_CTRL_TIE 0x10 /* Timer Interrupt Enable */
48#define RX8581_CTRL_AIE 0x08 /* Alarm Interrupt Enable */
49#define RX8581_CTRL_STOP 0x02 /* STOP bit */
50#define RX8581_CTRL_RESET 0x01 /* RESET bit */
51
52#define RX8571_USER_RAM 0x10
53#define RX8571_NVRAM_SIZE 0x10
54
55struct rx85x1_config {
56 struct regmap_config regmap;
57 unsigned int num_nvram;
58};
59
60/*
61 * In the routines that deal directly with the rx8581 hardware, we use
62 * rtc_time -- month 0-11, hour 0-23, yr = calendar year-epoch.
63 */
64static int rx8581_rtc_read_time(struct device *dev, struct rtc_time *tm)
65{
66 struct i2c_client *client = to_i2c_client(dev);
67 unsigned char date[7];
68 unsigned int data;
69 int err;
70 struct regmap *regmap = i2c_get_clientdata(client);
71
72 /* First we ensure that the "update flag" is not set, we read the
73 * time and date then re-read the "update flag". If the update flag
74 * has been set, we know that the time has changed during the read so
75 * we repeat the whole process again.
76 */
77 err = regmap_read(map: regmap, RX8581_REG_FLAG, val: &data);
78 if (err < 0)
79 return err;
80
81 if (data & RX8581_FLAG_VLF) {
82 dev_warn(dev,
83 "low voltage detected, date/time is not reliable.\n");
84 return -EINVAL;
85 }
86
87 do {
88 /* If update flag set, clear it */
89 if (data & RX8581_FLAG_UF) {
90 err = regmap_write(map: regmap, RX8581_REG_FLAG,
91 val: data & ~RX8581_FLAG_UF);
92 if (err < 0)
93 return err;
94 }
95
96 /* Now read time and date */
97 err = regmap_bulk_read(map: regmap, RX8581_REG_SC, val: date,
98 val_count: sizeof(date));
99 if (err < 0)
100 return err;
101
102 /* Check flag register */
103 err = regmap_read(map: regmap, RX8581_REG_FLAG, val: &data);
104 if (err < 0)
105 return err;
106 } while (data & RX8581_FLAG_UF);
107
108 dev_dbg(dev, "%s: raw data is sec=%02x, min=%02x, hr=%02x, "
109 "wday=%02x, mday=%02x, mon=%02x, year=%02x\n",
110 __func__,
111 date[0], date[1], date[2], date[3], date[4], date[5], date[6]);
112
113 tm->tm_sec = bcd2bin(date[RX8581_REG_SC] & 0x7F);
114 tm->tm_min = bcd2bin(date[RX8581_REG_MN] & 0x7F);
115 tm->tm_hour = bcd2bin(date[RX8581_REG_HR] & 0x3F); /* rtc hr 0-23 */
116 tm->tm_wday = ilog2(date[RX8581_REG_DW] & 0x7F);
117 tm->tm_mday = bcd2bin(date[RX8581_REG_DM] & 0x3F);
118 tm->tm_mon = bcd2bin(date[RX8581_REG_MO] & 0x1F) - 1; /* rtc mn 1-12 */
119 tm->tm_year = bcd2bin(date[RX8581_REG_YR]) + 100;
120
121 dev_dbg(dev, "%s: tm is secs=%d, mins=%d, hours=%d, "
122 "mday=%d, mon=%d, year=%d, wday=%d\n",
123 __func__,
124 tm->tm_sec, tm->tm_min, tm->tm_hour,
125 tm->tm_mday, tm->tm_mon, tm->tm_year, tm->tm_wday);
126
127 return 0;
128}
129
130static int rx8581_rtc_set_time(struct device *dev, struct rtc_time *tm)
131{
132 struct i2c_client *client = to_i2c_client(dev);
133 int err;
134 unsigned char buf[7];
135 struct regmap *regmap = i2c_get_clientdata(client);
136
137 dev_dbg(dev, "%s: secs=%d, mins=%d, hours=%d, "
138 "mday=%d, mon=%d, year=%d, wday=%d\n",
139 __func__,
140 tm->tm_sec, tm->tm_min, tm->tm_hour,
141 tm->tm_mday, tm->tm_mon, tm->tm_year, tm->tm_wday);
142
143 /* hours, minutes and seconds */
144 buf[RX8581_REG_SC] = bin2bcd(tm->tm_sec);
145 buf[RX8581_REG_MN] = bin2bcd(tm->tm_min);
146 buf[RX8581_REG_HR] = bin2bcd(tm->tm_hour);
147
148 buf[RX8581_REG_DM] = bin2bcd(tm->tm_mday);
149
150 /* month, 1 - 12 */
151 buf[RX8581_REG_MO] = bin2bcd(tm->tm_mon + 1);
152
153 /* year and century */
154 buf[RX8581_REG_YR] = bin2bcd(tm->tm_year - 100);
155 buf[RX8581_REG_DW] = (0x1 << tm->tm_wday);
156
157 /* Stop the clock */
158 err = regmap_update_bits(map: regmap, RX8581_REG_CTRL,
159 RX8581_CTRL_STOP, RX8581_CTRL_STOP);
160 if (err < 0)
161 return err;
162
163 /* write register's data */
164 err = regmap_bulk_write(map: regmap, RX8581_REG_SC, val: buf, val_count: sizeof(buf));
165 if (err < 0)
166 return err;
167
168 /* get VLF and clear it */
169 err = regmap_update_bits(map: regmap, RX8581_REG_FLAG, RX8581_FLAG_VLF, val: 0);
170 if (err < 0)
171 return err;
172
173 /* Restart the clock */
174 return regmap_update_bits(map: regmap, RX8581_REG_CTRL,
175 RX8581_CTRL_STOP, val: 0);
176}
177
178static const struct rtc_class_ops rx8581_rtc_ops = {
179 .read_time = rx8581_rtc_read_time,
180 .set_time = rx8581_rtc_set_time,
181};
182
183static int rx8571_nvram_read(void *priv, unsigned int offset, void *val,
184 size_t bytes)
185{
186 struct regmap *regmap = priv;
187
188 return regmap_bulk_read(map: regmap, RX8571_USER_RAM + offset, val, val_count: bytes);
189}
190
191static int rx8571_nvram_write(void *priv, unsigned int offset, void *val,
192 size_t bytes)
193{
194 struct regmap *regmap = priv;
195
196 return regmap_bulk_write(map: regmap, RX8571_USER_RAM + offset, val, val_count: bytes);
197}
198
199static int rx85x1_nvram_read(void *priv, unsigned int offset, void *val,
200 size_t bytes)
201{
202 struct regmap *regmap = priv;
203 unsigned int tmp_val;
204 int ret;
205
206 ret = regmap_read(map: regmap, RX8581_REG_RAM, val: &tmp_val);
207 (*(unsigned char *)val) = (unsigned char) tmp_val;
208
209 return ret;
210}
211
212static int rx85x1_nvram_write(void *priv, unsigned int offset, void *val,
213 size_t bytes)
214{
215 struct regmap *regmap = priv;
216 unsigned char tmp_val;
217
218 tmp_val = *((unsigned char *)val);
219 return regmap_write(map: regmap, RX8581_REG_RAM, val: (unsigned int)tmp_val);
220}
221
222static const struct rx85x1_config rx8581_config = {
223 .regmap = {
224 .reg_bits = 8,
225 .val_bits = 8,
226 .max_register = 0xf,
227 },
228 .num_nvram = 1
229};
230
231static const struct rx85x1_config rx8571_config = {
232 .regmap = {
233 .reg_bits = 8,
234 .val_bits = 8,
235 .max_register = 0x1f,
236 },
237 .num_nvram = 2
238};
239
240static int rx8581_probe(struct i2c_client *client)
241{
242 struct regmap *regmap;
243 const struct rx85x1_config *config = &rx8581_config;
244 const void *data = of_device_get_match_data(dev: &client->dev);
245 struct rtc_device *rtc;
246 static struct nvmem_config nvmem_cfg[] = {
247 {
248 .name = "rx85x1-",
249 .word_size = 1,
250 .stride = 1,
251 .size = 1,
252 .reg_read = rx85x1_nvram_read,
253 .reg_write = rx85x1_nvram_write,
254 }, {
255 .name = "rx8571-",
256 .word_size = 1,
257 .stride = 1,
258 .size = RX8571_NVRAM_SIZE,
259 .reg_read = rx8571_nvram_read,
260 .reg_write = rx8571_nvram_write,
261 },
262 };
263 int ret, i;
264
265 dev_dbg(&client->dev, "%s\n", __func__);
266
267 if (data)
268 config = data;
269
270 regmap = devm_regmap_init_i2c(client, &config->regmap);
271 if (IS_ERR(ptr: regmap))
272 return PTR_ERR(ptr: regmap);
273
274 i2c_set_clientdata(client, data: regmap);
275
276 rtc = devm_rtc_allocate_device(dev: &client->dev);
277 if (IS_ERR(ptr: rtc))
278 return PTR_ERR(ptr: rtc);
279
280 rtc->ops = &rx8581_rtc_ops;
281 rtc->range_min = RTC_TIMESTAMP_BEGIN_2000;
282 rtc->range_max = RTC_TIMESTAMP_END_2099;
283 rtc->start_secs = 0;
284 rtc->set_start_time = true;
285
286 ret = devm_rtc_register_device(rtc);
287
288 for (i = 0; i < config->num_nvram; i++) {
289 nvmem_cfg[i].priv = regmap;
290 devm_rtc_nvmem_register(rtc, nvmem_config: &nvmem_cfg[i]);
291 }
292
293 return ret;
294}
295
296static const struct i2c_device_id rx8581_id[] = {
297 { "rx8581" },
298 { }
299};
300MODULE_DEVICE_TABLE(i2c, rx8581_id);
301
302static const __maybe_unused struct of_device_id rx8581_of_match[] = {
303 { .compatible = "epson,rx8571", .data = &rx8571_config },
304 { .compatible = "epson,rx8581", .data = &rx8581_config },
305 { /* sentinel */ }
306};
307MODULE_DEVICE_TABLE(of, rx8581_of_match);
308
309static struct i2c_driver rx8581_driver = {
310 .driver = {
311 .name = "rtc-rx8581",
312 .of_match_table = of_match_ptr(rx8581_of_match),
313 },
314 .probe = rx8581_probe,
315 .id_table = rx8581_id,
316};
317
318module_i2c_driver(rx8581_driver);
319
320MODULE_AUTHOR("Martyn Welch <martyn.welch@ge.com>");
321MODULE_DESCRIPTION("Epson RX-8571/RX-8581 RTC driver");
322MODULE_LICENSE("GPL");
323

source code of linux/drivers/rtc/rtc-rx8581.c