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1/*
2 * Driver for the Epson RTC module RX-6110 SA
3 *
4 * Copyright(C) 2015 Pengutronix, Steffen Trumtrar <kernel@pengutronix.de>
5 * Copyright(C) SEIKO EPSON CORPORATION 2013. All rights reserved.
6 *
7 * This driver software is distributed as is, without any warranty of any kind,
8 * either express or implied as further specified in the GNU Public License.
9 * This software may be used and distributed according to the terms of the GNU
10 * Public License, version 2 as published by the Free Software Foundation.
11 * See the file COPYING in the main directory of this archive for more details.
12 *
13 * You should have received a copy of the GNU General Public License along with
14 * this program. If not, see <http://www.gnu.org/licenses/>.
15 */
16
17#include <linux/bcd.h>
18#include <linux/init.h>
19#include <linux/kernel.h>
20#include <linux/module.h>
21#include <linux/of_gpio.h>
22#include <linux/regmap.h>
23#include <linux/rtc.h>
24#include <linux/spi/spi.h>
25
26/* RX-6110 Register definitions */
27#define RX6110_REG_SEC 0x10
28#define RX6110_REG_MIN 0x11
29#define RX6110_REG_HOUR 0x12
30#define RX6110_REG_WDAY 0x13
31#define RX6110_REG_MDAY 0x14
32#define RX6110_REG_MONTH 0x15
33#define RX6110_REG_YEAR 0x16
34#define RX6110_REG_RES1 0x17
35#define RX6110_REG_ALMIN 0x18
36#define RX6110_REG_ALHOUR 0x19
37#define RX6110_REG_ALWDAY 0x1A
38#define RX6110_REG_TCOUNT0 0x1B
39#define RX6110_REG_TCOUNT1 0x1C
40#define RX6110_REG_EXT 0x1D
41#define RX6110_REG_FLAG 0x1E
42#define RX6110_REG_CTRL 0x1F
43#define RX6110_REG_USER0 0x20
44#define RX6110_REG_USER1 0x21
45#define RX6110_REG_USER2 0x22
46#define RX6110_REG_USER3 0x23
47#define RX6110_REG_USER4 0x24
48#define RX6110_REG_USER5 0x25
49#define RX6110_REG_USER6 0x26
50#define RX6110_REG_USER7 0x27
51#define RX6110_REG_USER8 0x28
52#define RX6110_REG_USER9 0x29
53#define RX6110_REG_USERA 0x2A
54#define RX6110_REG_USERB 0x2B
55#define RX6110_REG_USERC 0x2C
56#define RX6110_REG_USERD 0x2D
57#define RX6110_REG_USERE 0x2E
58#define RX6110_REG_USERF 0x2F
59#define RX6110_REG_RES2 0x30
60#define RX6110_REG_RES3 0x31
61#define RX6110_REG_IRQ 0x32
62
63#define RX6110_BIT_ALARM_EN BIT(7)
64
65/* Extension Register (1Dh) bit positions */
66#define RX6110_BIT_EXT_TSEL0 BIT(0)
67#define RX6110_BIT_EXT_TSEL1 BIT(1)
68#define RX6110_BIT_EXT_TSEL2 BIT(2)
69#define RX6110_BIT_EXT_WADA BIT(3)
70#define RX6110_BIT_EXT_TE BIT(4)
71#define RX6110_BIT_EXT_USEL BIT(5)
72#define RX6110_BIT_EXT_FSEL0 BIT(6)
73#define RX6110_BIT_EXT_FSEL1 BIT(7)
74
75/* Flag Register (1Eh) bit positions */
76#define RX6110_BIT_FLAG_VLF BIT(1)
77#define RX6110_BIT_FLAG_AF BIT(3)
78#define RX6110_BIT_FLAG_TF BIT(4)
79#define RX6110_BIT_FLAG_UF BIT(5)
80
81/* Control Register (1Fh) bit positions */
82#define RX6110_BIT_CTRL_TBKE BIT(0)
83#define RX6110_BIT_CTRL_TBKON BIT(1)
84#define RX6110_BIT_CTRL_TSTP BIT(2)
85#define RX6110_BIT_CTRL_AIE BIT(3)
86#define RX6110_BIT_CTRL_TIE BIT(4)
87#define RX6110_BIT_CTRL_UIE BIT(5)
88#define RX6110_BIT_CTRL_STOP BIT(6)
89#define RX6110_BIT_CTRL_TEST BIT(7)
90
91enum {
92 RTC_SEC = 0,
93 RTC_MIN,
94 RTC_HOUR,
95 RTC_WDAY,
96 RTC_MDAY,
97 RTC_MONTH,
98 RTC_YEAR,
99 RTC_NR_TIME
100};
101
102#define RX6110_DRIVER_NAME "rx6110"
103
104struct rx6110_data {
105 struct rtc_device *rtc;
106 struct regmap *regmap;
107};
108
109/**
110 * rx6110_rtc_tm_to_data - convert rtc_time to native time encoding
111 *
112 * @tm: holds date and time
113 * @data: holds the encoding in rx6110 native form
114 */
115static int rx6110_rtc_tm_to_data(struct rtc_time *tm, u8 *data)
116{
117 pr_debug("%s: date %ds %dm %dh %dmd %dm %dy\n", __func__,
118 tm->tm_sec, tm->tm_min, tm->tm_hour,
119 tm->tm_mday, tm->tm_mon, tm->tm_year);
120
121 /*
122 * The year in the RTC is a value between 0 and 99.
123 * Assume that this represents the current century
124 * and disregard all other values.
125 */
126 if (tm->tm_year < 100 || tm->tm_year >= 200)
127 return -EINVAL;
128
129 data[RTC_SEC] = bin2bcd(tm->tm_sec);
130 data[RTC_MIN] = bin2bcd(tm->tm_min);
131 data[RTC_HOUR] = bin2bcd(tm->tm_hour);
132 data[RTC_WDAY] = BIT(bin2bcd(tm->tm_wday));
133 data[RTC_MDAY] = bin2bcd(tm->tm_mday);
134 data[RTC_MONTH] = bin2bcd(tm->tm_mon + 1);
135 data[RTC_YEAR] = bin2bcd(tm->tm_year % 100);
136
137 return 0;
138}
139
140/**
141 * rx6110_data_to_rtc_tm - convert native time encoding to rtc_time
142 *
143 * @data: holds the encoding in rx6110 native form
144 * @tm: holds date and time
145 */
146static int rx6110_data_to_rtc_tm(u8 *data, struct rtc_time *tm)
147{
148 tm->tm_sec = bcd2bin(data[RTC_SEC] & 0x7f);
149 tm->tm_min = bcd2bin(data[RTC_MIN] & 0x7f);
150 /* only 24-hour clock */
151 tm->tm_hour = bcd2bin(data[RTC_HOUR] & 0x3f);
152 tm->tm_wday = ffs(data[RTC_WDAY] & 0x7f);
153 tm->tm_mday = bcd2bin(data[RTC_MDAY] & 0x3f);
154 tm->tm_mon = bcd2bin(data[RTC_MONTH] & 0x1f) - 1;
155 tm->tm_year = bcd2bin(data[RTC_YEAR]) + 100;
156
157 pr_debug("%s: date %ds %dm %dh %dmd %dm %dy\n", __func__,
158 tm->tm_sec, tm->tm_min, tm->tm_hour,
159 tm->tm_mday, tm->tm_mon, tm->tm_year);
160
161 /*
162 * The year in the RTC is a value between 0 and 99.
163 * Assume that this represents the current century
164 * and disregard all other values.
165 */
166 if (tm->tm_year < 100 || tm->tm_year >= 200)
167 return -EINVAL;
168
169 return 0;
170}
171
172/**
173 * rx6110_set_time - set the current time in the rx6110 registers
174 *
175 * @dev: the rtc device in use
176 * @tm: holds date and time
177 *
178 * BUG: The HW assumes every year that is a multiple of 4 to be a leap
179 * year. Next time this is wrong is 2100, which will not be a leap year
180 *
181 * Note: If STOP is not set/cleared, the clock will start when the seconds
182 * register is written
183 *
184 */
185static int rx6110_set_time(struct device *dev, struct rtc_time *tm)
186{
187 struct rx6110_data *rx6110 = dev_get_drvdata(dev);
188 u8 data[RTC_NR_TIME];
189 int ret;
190
191 ret = rx6110_rtc_tm_to_data(tm, data);
192 if (ret < 0)
193 return ret;
194
195 /* set STOP bit before changing clock/calendar */
196 ret = regmap_update_bits(rx6110->regmap, RX6110_REG_CTRL,
197 RX6110_BIT_CTRL_STOP, RX6110_BIT_CTRL_STOP);
198 if (ret)
199 return ret;
200
201 ret = regmap_bulk_write(rx6110->regmap, RX6110_REG_SEC, data,
202 RTC_NR_TIME);
203 if (ret)
204 return ret;
205
206 /* The time in the RTC is valid. Be sure to have VLF cleared. */
207 ret = regmap_update_bits(rx6110->regmap, RX6110_REG_FLAG,
208 RX6110_BIT_FLAG_VLF, 0);
209 if (ret)
210 return ret;
211
212 /* clear STOP bit after changing clock/calendar */
213 ret = regmap_update_bits(rx6110->regmap, RX6110_REG_CTRL,
214 RX6110_BIT_CTRL_STOP, 0);
215
216 return ret;
217}
218
219/**
220 * rx6110_get_time - get the current time from the rx6110 registers
221 * @dev: the rtc device in use
222 * @tm: holds date and time
223 */
224static int rx6110_get_time(struct device *dev, struct rtc_time *tm)
225{
226 struct rx6110_data *rx6110 = dev_get_drvdata(dev);
227 u8 data[RTC_NR_TIME];
228 int flags;
229 int ret;
230
231 ret = regmap_read(rx6110->regmap, RX6110_REG_FLAG, &flags);
232 if (ret)
233 return -EINVAL;
234
235 /* check for VLF Flag (set at power-on) */
236 if ((flags & RX6110_BIT_FLAG_VLF)) {
237 dev_warn(dev, "Voltage low, data is invalid.\n");
238 return -EINVAL;
239 }
240
241 /* read registers to date */
242 ret = regmap_bulk_read(rx6110->regmap, RX6110_REG_SEC, data,
243 RTC_NR_TIME);
244 if (ret)
245 return ret;
246
247 ret = rx6110_data_to_rtc_tm(data, tm);
248 if (ret)
249 return ret;
250
251 dev_dbg(dev, "%s: date %ds %dm %dh %dmd %dm %dy\n", __func__,
252 tm->tm_sec, tm->tm_min, tm->tm_hour,
253 tm->tm_mday, tm->tm_mon, tm->tm_year);
254
255 return 0;
256}
257
258static const struct reg_sequence rx6110_default_regs[] = {
259 { RX6110_REG_RES1, 0xB8 },
260 { RX6110_REG_RES2, 0x00 },
261 { RX6110_REG_RES3, 0x10 },
262 { RX6110_REG_IRQ, 0x00 },
263 { RX6110_REG_ALMIN, 0x00 },
264 { RX6110_REG_ALHOUR, 0x00 },
265 { RX6110_REG_ALWDAY, 0x00 },
266};
267
268/**
269 * rx6110_init - initialize the rx6110 registers
270 *
271 * @rx6110: pointer to the rx6110 struct in use
272 *
273 */
274static int rx6110_init(struct rx6110_data *rx6110)
275{
276 struct rtc_device *rtc = rx6110->rtc;
277 int flags;
278 int ret;
279
280 ret = regmap_update_bits(rx6110->regmap, RX6110_REG_EXT,
281 RX6110_BIT_EXT_TE, 0);
282 if (ret)
283 return ret;
284
285 ret = regmap_register_patch(rx6110->regmap, rx6110_default_regs,
286 ARRAY_SIZE(rx6110_default_regs));
287 if (ret)
288 return ret;
289
290 ret = regmap_read(rx6110->regmap, RX6110_REG_FLAG, &flags);
291 if (ret)
292 return ret;
293
294 /* check for VLF Flag (set at power-on) */
295 if ((flags & RX6110_BIT_FLAG_VLF))
296 dev_warn(&rtc->dev, "Voltage low, data loss detected.\n");
297
298 /* check for Alarm Flag */
299 if (flags & RX6110_BIT_FLAG_AF)
300 dev_warn(&rtc->dev, "An alarm may have been missed.\n");
301
302 /* check for Periodic Timer Flag */
303 if (flags & RX6110_BIT_FLAG_TF)
304 dev_warn(&rtc->dev, "Periodic timer was detected\n");
305
306 /* check for Update Timer Flag */
307 if (flags & RX6110_BIT_FLAG_UF)
308 dev_warn(&rtc->dev, "Update timer was detected\n");
309
310 /* clear all flags BUT VLF */
311 ret = regmap_update_bits(rx6110->regmap, RX6110_REG_FLAG,
312 RX6110_BIT_FLAG_AF |
313 RX6110_BIT_FLAG_UF |
314 RX6110_BIT_FLAG_TF,
315 0);
316
317 return ret;
318}
319
320static const struct rtc_class_ops rx6110_rtc_ops = {
321 .read_time = rx6110_get_time,
322 .set_time = rx6110_set_time,
323};
324
325static struct regmap_config regmap_spi_config = {
326 .reg_bits = 8,
327 .val_bits = 8,
328 .max_register = RX6110_REG_IRQ,
329 .read_flag_mask = 0x80,
330};
331
332/**
333 * rx6110_probe - initialize rtc driver
334 * @spi: pointer to spi device
335 */
336static int rx6110_probe(struct spi_device *spi)
337{
338 struct rx6110_data *rx6110;
339 int err;
340
341 if ((spi->bits_per_word && spi->bits_per_word != 8) ||
342 (spi->max_speed_hz > 2000000) ||
343 (spi->mode != (SPI_CS_HIGH | SPI_CPOL | SPI_CPHA))) {
344 dev_warn(&spi->dev, "SPI settings: bits_per_word: %d, max_speed_hz: %d, mode: %xh\n",
345 spi->bits_per_word, spi->max_speed_hz, spi->mode);
346 dev_warn(&spi->dev, "driving device in an unsupported mode");
347 }
348
349 rx6110 = devm_kzalloc(&spi->dev, sizeof(*rx6110), GFP_KERNEL);
350 if (!rx6110)
351 return -ENOMEM;
352
353 rx6110->regmap = devm_regmap_init_spi(spi, ®map_spi_config);
354 if (IS_ERR(rx6110->regmap)) {
355 dev_err(&spi->dev, "regmap init failed for rtc rx6110\n");
356 return PTR_ERR(rx6110->regmap);
357 }
358
359 spi_set_drvdata(spi, rx6110);
360
361 rx6110->rtc = devm_rtc_device_register(&spi->dev,
362 RX6110_DRIVER_NAME,
363 &rx6110_rtc_ops, THIS_MODULE);
364
365 if (IS_ERR(rx6110->rtc))
366 return PTR_ERR(rx6110->rtc);
367
368 err = rx6110_init(rx6110);
369 if (err)
370 return err;
371
372 rx6110->rtc->max_user_freq = 1;
373
374 return 0;
375}
376
377static int rx6110_remove(struct spi_device *spi)
378{
379 return 0;
380}
381
382static const struct spi_device_id rx6110_id[] = {
383 { "rx6110", 0 },
384 { }
385};
386MODULE_DEVICE_TABLE(spi, rx6110_id);
387
388static struct spi_driver rx6110_driver = {
389 .driver = {
390 .name = RX6110_DRIVER_NAME,
391 },
392 .probe = rx6110_probe,
393 .remove = rx6110_remove,
394 .id_table = rx6110_id,
395};
396
397module_spi_driver(rx6110_driver);
398
399MODULE_AUTHOR("Val Krutov <val.krutov@erd.epson.com>");
400MODULE_DESCRIPTION("RX-6110 SA RTC driver");
401MODULE_LICENSE("GPL");