1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * Driver for the Epson RTC module RX-6110 SA
4 *
5 * Copyright(C) 2015 Pengutronix, Steffen Trumtrar <kernel@pengutronix.de>
6 * Copyright(C) SEIKO EPSON CORPORATION 2013. All rights reserved.
7 */
8
9#include <linux/bcd.h>
10#include <linux/init.h>
11#include <linux/kernel.h>
12#include <linux/module.h>
13#include <linux/of_gpio.h>
14#include <linux/regmap.h>
15#include <linux/rtc.h>
16#include <linux/of.h>
17#include <linux/of_device.h>
18#include <linux/spi/spi.h>
19
20/* RX-6110 Register definitions */
21#define RX6110_REG_SEC		0x10
22#define RX6110_REG_MIN		0x11
23#define RX6110_REG_HOUR		0x12
24#define RX6110_REG_WDAY		0x13
25#define RX6110_REG_MDAY		0x14
26#define RX6110_REG_MONTH	0x15
27#define RX6110_REG_YEAR		0x16
28#define RX6110_REG_RES1		0x17
29#define RX6110_REG_ALMIN	0x18
30#define RX6110_REG_ALHOUR	0x19
31#define RX6110_REG_ALWDAY	0x1A
32#define RX6110_REG_TCOUNT0	0x1B
33#define RX6110_REG_TCOUNT1	0x1C
34#define RX6110_REG_EXT		0x1D
35#define RX6110_REG_FLAG		0x1E
36#define RX6110_REG_CTRL		0x1F
37#define RX6110_REG_USER0	0x20
38#define RX6110_REG_USER1	0x21
39#define RX6110_REG_USER2	0x22
40#define RX6110_REG_USER3	0x23
41#define RX6110_REG_USER4	0x24
42#define RX6110_REG_USER5	0x25
43#define RX6110_REG_USER6	0x26
44#define RX6110_REG_USER7	0x27
45#define RX6110_REG_USER8	0x28
46#define RX6110_REG_USER9	0x29
47#define RX6110_REG_USERA	0x2A
48#define RX6110_REG_USERB	0x2B
49#define RX6110_REG_USERC	0x2C
50#define RX6110_REG_USERD	0x2D
51#define RX6110_REG_USERE	0x2E
52#define RX6110_REG_USERF	0x2F
53#define RX6110_REG_RES2		0x30
54#define RX6110_REG_RES3		0x31
55#define RX6110_REG_IRQ		0x32
56
57#define RX6110_BIT_ALARM_EN		BIT(7)
58
59/* Extension Register (1Dh) bit positions */
60#define RX6110_BIT_EXT_TSEL0		BIT(0)
61#define RX6110_BIT_EXT_TSEL1		BIT(1)
62#define RX6110_BIT_EXT_TSEL2		BIT(2)
63#define RX6110_BIT_EXT_WADA		BIT(3)
64#define RX6110_BIT_EXT_TE		BIT(4)
65#define RX6110_BIT_EXT_USEL		BIT(5)
66#define RX6110_BIT_EXT_FSEL0		BIT(6)
67#define RX6110_BIT_EXT_FSEL1		BIT(7)
68
69/* Flag Register (1Eh) bit positions */
70#define RX6110_BIT_FLAG_VLF		BIT(1)
71#define RX6110_BIT_FLAG_AF		BIT(3)
72#define RX6110_BIT_FLAG_TF		BIT(4)
73#define RX6110_BIT_FLAG_UF		BIT(5)
74
75/* Control Register (1Fh) bit positions */
76#define RX6110_BIT_CTRL_TBKE		BIT(0)
77#define RX6110_BIT_CTRL_TBKON		BIT(1)
78#define RX6110_BIT_CTRL_TSTP		BIT(2)
79#define RX6110_BIT_CTRL_AIE		BIT(3)
80#define RX6110_BIT_CTRL_TIE		BIT(4)
81#define RX6110_BIT_CTRL_UIE		BIT(5)
82#define RX6110_BIT_CTRL_STOP		BIT(6)
83#define RX6110_BIT_CTRL_TEST		BIT(7)
84
85enum {
86	RTC_SEC = 0,
87	RTC_MIN,
88	RTC_HOUR,
89	RTC_WDAY,
90	RTC_MDAY,
91	RTC_MONTH,
92	RTC_YEAR,
93	RTC_NR_TIME
94};
95
96#define RX6110_DRIVER_NAME		"rx6110"
97
98struct rx6110_data {
99	struct rtc_device *rtc;
100	struct regmap *regmap;
101};
102
103/**
104 * rx6110_rtc_tm_to_data - convert rtc_time to native time encoding
105 *
106 * @tm: holds date and time
107 * @data: holds the encoding in rx6110 native form
108 */
109static int rx6110_rtc_tm_to_data(struct rtc_time *tm, u8 *data)
110{
111	pr_debug("%s: date %ptRr\n", __func__, tm);
112
113	/*
114	 * The year in the RTC is a value between 0 and 99.
115	 * Assume that this represents the current century
116	 * and disregard all other values.
117	 */
118	if (tm->tm_year < 100 || tm->tm_year >= 200)
119		return -EINVAL;
120
121	data[RTC_SEC] = bin2bcd(tm->tm_sec);
122	data[RTC_MIN] = bin2bcd(tm->tm_min);
123	data[RTC_HOUR] = bin2bcd(tm->tm_hour);
124	data[RTC_WDAY] = BIT(bin2bcd(tm->tm_wday));
125	data[RTC_MDAY] = bin2bcd(tm->tm_mday);
126	data[RTC_MONTH] = bin2bcd(tm->tm_mon + 1);
127	data[RTC_YEAR] = bin2bcd(tm->tm_year % 100);
128
129	return 0;
130}
131
132/**
133 * rx6110_data_to_rtc_tm - convert native time encoding to rtc_time
134 *
135 * @data: holds the encoding in rx6110 native form
136 * @tm: holds date and time
137 */
138static int rx6110_data_to_rtc_tm(u8 *data, struct rtc_time *tm)
139{
140	tm->tm_sec = bcd2bin(data[RTC_SEC] & 0x7f);
141	tm->tm_min = bcd2bin(data[RTC_MIN] & 0x7f);
142	/* only 24-hour clock */
143	tm->tm_hour = bcd2bin(data[RTC_HOUR] & 0x3f);
144	tm->tm_wday = ffs(data[RTC_WDAY] & 0x7f);
145	tm->tm_mday = bcd2bin(data[RTC_MDAY] & 0x3f);
146	tm->tm_mon = bcd2bin(data[RTC_MONTH] & 0x1f) - 1;
147	tm->tm_year = bcd2bin(data[RTC_YEAR]) + 100;
148
149	pr_debug("%s: date %ptRr\n", __func__, tm);
150
151	/*
152	 * The year in the RTC is a value between 0 and 99.
153	 * Assume that this represents the current century
154	 * and disregard all other values.
155	 */
156	if (tm->tm_year < 100 || tm->tm_year >= 200)
157		return -EINVAL;
158
159	return 0;
160}
161
162/**
163 * rx6110_set_time - set the current time in the rx6110 registers
164 *
165 * @dev: the rtc device in use
166 * @tm: holds date and time
167 *
168 * BUG: The HW assumes every year that is a multiple of 4 to be a leap
169 * year. Next time this is wrong is 2100, which will not be a leap year
170 *
171 * Note: If STOP is not set/cleared, the clock will start when the seconds
172 *       register is written
173 *
174 */
175static int rx6110_set_time(struct device *dev, struct rtc_time *tm)
176{
177	struct rx6110_data *rx6110 = dev_get_drvdata(dev);
178	u8 data[RTC_NR_TIME];
179	int ret;
180
181	ret = rx6110_rtc_tm_to_data(tm, data);
182	if (ret < 0)
183		return ret;
184
185	/* set STOP bit before changing clock/calendar */
186	ret = regmap_update_bits(rx6110->regmap, RX6110_REG_CTRL,
187				 RX6110_BIT_CTRL_STOP, RX6110_BIT_CTRL_STOP);
188	if (ret)
189		return ret;
190
191	ret = regmap_bulk_write(rx6110->regmap, RX6110_REG_SEC, data,
192				RTC_NR_TIME);
193	if (ret)
194		return ret;
195
196	/* The time in the RTC is valid. Be sure to have VLF cleared. */
197	ret = regmap_update_bits(rx6110->regmap, RX6110_REG_FLAG,
198				 RX6110_BIT_FLAG_VLF, 0);
199	if (ret)
200		return ret;
201
202	/* clear STOP bit after changing clock/calendar */
203	ret = regmap_update_bits(rx6110->regmap, RX6110_REG_CTRL,
204				 RX6110_BIT_CTRL_STOP, 0);
205
206	return ret;
207}
208
209/**
210 * rx6110_get_time - get the current time from the rx6110 registers
211 * @dev: the rtc device in use
212 * @tm: holds date and time
213 */
214static int rx6110_get_time(struct device *dev, struct rtc_time *tm)
215{
216	struct rx6110_data *rx6110 = dev_get_drvdata(dev);
217	u8 data[RTC_NR_TIME];
218	int flags;
219	int ret;
220
221	ret = regmap_read(rx6110->regmap, RX6110_REG_FLAG, &flags);
222	if (ret)
223		return -EINVAL;
224
225	/* check for VLF Flag (set at power-on) */
226	if ((flags & RX6110_BIT_FLAG_VLF)) {
227		dev_warn(dev, "Voltage low, data is invalid.\n");
228		return -EINVAL;
229	}
230
231	/* read registers to date */
232	ret = regmap_bulk_read(rx6110->regmap, RX6110_REG_SEC, data,
233			       RTC_NR_TIME);
234	if (ret)
235		return ret;
236
237	ret = rx6110_data_to_rtc_tm(data, tm);
238	if (ret)
239		return ret;
240
241	dev_dbg(dev, "%s: date %ptRr\n", __func__, tm);
242
243	return 0;
244}
245
246static const struct reg_sequence rx6110_default_regs[] = {
247	{ RX6110_REG_RES1,   0xB8 },
248	{ RX6110_REG_RES2,   0x00 },
249	{ RX6110_REG_RES3,   0x10 },
250	{ RX6110_REG_IRQ,    0x00 },
251	{ RX6110_REG_ALMIN,  0x00 },
252	{ RX6110_REG_ALHOUR, 0x00 },
253	{ RX6110_REG_ALWDAY, 0x00 },
254};
255
256/**
257 * rx6110_init - initialize the rx6110 registers
258 *
259 * @rx6110: pointer to the rx6110 struct in use
260 *
261 */
262static int rx6110_init(struct rx6110_data *rx6110)
263{
264	struct rtc_device *rtc = rx6110->rtc;
265	int flags;
266	int ret;
267
268	ret = regmap_update_bits(rx6110->regmap, RX6110_REG_EXT,
269				 RX6110_BIT_EXT_TE, 0);
270	if (ret)
271		return ret;
272
273	ret = regmap_register_patch(rx6110->regmap, rx6110_default_regs,
274				    ARRAY_SIZE(rx6110_default_regs));
275	if (ret)
276		return ret;
277
278	ret = regmap_read(rx6110->regmap, RX6110_REG_FLAG, &flags);
279	if (ret)
280		return ret;
281
282	/* check for VLF Flag (set at power-on) */
283	if ((flags & RX6110_BIT_FLAG_VLF))
284		dev_warn(&rtc->dev, "Voltage low, data loss detected.\n");
285
286	/* check for Alarm Flag */
287	if (flags & RX6110_BIT_FLAG_AF)
288		dev_warn(&rtc->dev, "An alarm may have been missed.\n");
289
290	/* check for Periodic Timer Flag */
291	if (flags & RX6110_BIT_FLAG_TF)
292		dev_warn(&rtc->dev, "Periodic timer was detected\n");
293
294	/* check for Update Timer Flag */
295	if (flags & RX6110_BIT_FLAG_UF)
296		dev_warn(&rtc->dev, "Update timer was detected\n");
297
298	/* clear all flags BUT VLF */
299	ret = regmap_update_bits(rx6110->regmap, RX6110_REG_FLAG,
300				 RX6110_BIT_FLAG_AF |
301				 RX6110_BIT_FLAG_UF |
302				 RX6110_BIT_FLAG_TF,
303				 0);
304
305	return ret;
306}
307
308static const struct rtc_class_ops rx6110_rtc_ops = {
309	.read_time = rx6110_get_time,
310	.set_time = rx6110_set_time,
311};
312
313static struct regmap_config regmap_spi_config = {
314	.reg_bits = 8,
315	.val_bits = 8,
316	.max_register = RX6110_REG_IRQ,
317	.read_flag_mask = 0x80,
318};
319
320/**
321 * rx6110_probe - initialize rtc driver
322 * @spi: pointer to spi device
323 */
324static int rx6110_probe(struct spi_device *spi)
325{
326	struct rx6110_data *rx6110;
327	int err;
328
329	if ((spi->bits_per_word && spi->bits_per_word != 8) ||
330	    (spi->max_speed_hz > 2000000) ||
331	    (spi->mode != (SPI_CS_HIGH | SPI_CPOL | SPI_CPHA))) {
332		dev_warn(&spi->dev, "SPI settings: bits_per_word: %d, max_speed_hz: %d, mode: %xh\n",
333			 spi->bits_per_word, spi->max_speed_hz, spi->mode);
334		dev_warn(&spi->dev, "driving device in an unsupported mode");
335	}
336
337	rx6110 = devm_kzalloc(&spi->dev, sizeof(*rx6110), GFP_KERNEL);
338	if (!rx6110)
339		return -ENOMEM;
340
341	rx6110->regmap = devm_regmap_init_spi(spi, &regmap_spi_config);
342	if (IS_ERR(rx6110->regmap)) {
343		dev_err(&spi->dev, "regmap init failed for rtc rx6110\n");
344		return PTR_ERR(rx6110->regmap);
345	}
346
347	spi_set_drvdata(spi, rx6110);
348
349	rx6110->rtc = devm_rtc_device_register(&spi->dev,
350					       RX6110_DRIVER_NAME,
351					       &rx6110_rtc_ops, THIS_MODULE);
352
353	if (IS_ERR(rx6110->rtc))
354		return PTR_ERR(rx6110->rtc);
355
356	err = rx6110_init(rx6110);
357	if (err)
358		return err;
359
360	rx6110->rtc->max_user_freq = 1;
361
362	return 0;
363}
364
365static const struct spi_device_id rx6110_id[] = {
366	{ "rx6110", 0 },
367	{ }
368};
369MODULE_DEVICE_TABLE(spi, rx6110_id);
370
371static const struct of_device_id rx6110_spi_of_match[] = {
372	{ .compatible = "epson,rx6110" },
373	{ },
374};
375MODULE_DEVICE_TABLE(of, rx6110_spi_of_match);
376
377static struct spi_driver rx6110_driver = {
378	.driver = {
379		.name = RX6110_DRIVER_NAME,
380		.of_match_table = of_match_ptr(rx6110_spi_of_match),
381	},
382	.probe		= rx6110_probe,
383	.id_table	= rx6110_id,
384};
385
386module_spi_driver(rx6110_driver);
387
388MODULE_AUTHOR("Val Krutov <val.krutov@erd.epson.com>");
389MODULE_DESCRIPTION("RX-6110 SA RTC driver");
390MODULE_LICENSE("GPL");
391