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 rx8581 {
56	struct regmap		*regmap;
57	struct rtc_device	*rtc;
58};
59
60struct rx85x1_config {
61	struct regmap_config regmap;
62	unsigned int num_nvram;
63};
64
65/*
66 * In the routines that deal directly with the rx8581 hardware, we use
67 * rtc_time -- month 0-11, hour 0-23, yr = calendar year-epoch.
68 */
69static int rx8581_rtc_read_time(struct device *dev, struct rtc_time *tm)
70{
71	struct i2c_client *client = to_i2c_client(dev);
72	unsigned char date[7];
73	unsigned int data;
74	int err;
75	struct rx8581 *rx8581 = i2c_get_clientdata(client);
76
77	/* First we ensure that the "update flag" is not set, we read the
78	 * time and date then re-read the "update flag". If the update flag
79	 * has been set, we know that the time has changed during the read so
80	 * we repeat the whole process again.
81	 */
82	err = regmap_read(rx8581->regmap, RX8581_REG_FLAG, &data);
83	if (err < 0)
84		return err;
85
86	if (data & RX8581_FLAG_VLF) {
87		dev_warn(dev,
88			 "low voltage detected, date/time is not reliable.\n");
89		return -EINVAL;
90	}
91
92	do {
93		/* If update flag set, clear it */
94		if (data & RX8581_FLAG_UF) {
95			err = regmap_write(rx8581->regmap, RX8581_REG_FLAG,
96					  data & ~RX8581_FLAG_UF);
97			if (err < 0)
98				return err;
99		}
100
101		/* Now read time and date */
102		err = regmap_bulk_read(rx8581->regmap, RX8581_REG_SC, date,
103				       sizeof(date));
104		if (err < 0)
105			return err;
106
107		/* Check flag register */
108		err = regmap_read(rx8581->regmap, RX8581_REG_FLAG, &data);
109		if (err < 0)
110			return err;
111	} while (data & RX8581_FLAG_UF);
112
113	dev_dbg(dev, "%s: raw data is sec=%02x, min=%02x, hr=%02x, "
114		"wday=%02x, mday=%02x, mon=%02x, year=%02x\n",
115		__func__,
116		date[0], date[1], date[2], date[3], date[4], date[5], date[6]);
117
118	tm->tm_sec = bcd2bin(date[RX8581_REG_SC] & 0x7F);
119	tm->tm_min = bcd2bin(date[RX8581_REG_MN] & 0x7F);
120	tm->tm_hour = bcd2bin(date[RX8581_REG_HR] & 0x3F); /* rtc hr 0-23 */
121	tm->tm_wday = ilog2(date[RX8581_REG_DW] & 0x7F);
122	tm->tm_mday = bcd2bin(date[RX8581_REG_DM] & 0x3F);
123	tm->tm_mon = bcd2bin(date[RX8581_REG_MO] & 0x1F) - 1; /* rtc mn 1-12 */
124	tm->tm_year = bcd2bin(date[RX8581_REG_YR]) + 100;
125
126	dev_dbg(dev, "%s: tm is secs=%d, mins=%d, hours=%d, "
127		"mday=%d, mon=%d, year=%d, wday=%d\n",
128		__func__,
129		tm->tm_sec, tm->tm_min, tm->tm_hour,
130		tm->tm_mday, tm->tm_mon, tm->tm_year, tm->tm_wday);
131
132	return 0;
133}
134
135static int rx8581_rtc_set_time(struct device *dev, struct rtc_time *tm)
136{
137	struct i2c_client *client = to_i2c_client(dev);
138	int err;
139	unsigned char buf[7];
140	struct rx8581 *rx8581 = i2c_get_clientdata(client);
141
142	dev_dbg(dev, "%s: secs=%d, mins=%d, hours=%d, "
143		"mday=%d, mon=%d, year=%d, wday=%d\n",
144		__func__,
145		tm->tm_sec, tm->tm_min, tm->tm_hour,
146		tm->tm_mday, tm->tm_mon, tm->tm_year, tm->tm_wday);
147
148	/* hours, minutes and seconds */
149	buf[RX8581_REG_SC] = bin2bcd(tm->tm_sec);
150	buf[RX8581_REG_MN] = bin2bcd(tm->tm_min);
151	buf[RX8581_REG_HR] = bin2bcd(tm->tm_hour);
152
153	buf[RX8581_REG_DM] = bin2bcd(tm->tm_mday);
154
155	/* month, 1 - 12 */
156	buf[RX8581_REG_MO] = bin2bcd(tm->tm_mon + 1);
157
158	/* year and century */
159	buf[RX8581_REG_YR] = bin2bcd(tm->tm_year - 100);
160	buf[RX8581_REG_DW] = (0x1 << tm->tm_wday);
161
162	/* Stop the clock */
163	err = regmap_update_bits(rx8581->regmap, RX8581_REG_CTRL,
164				 RX8581_CTRL_STOP, RX8581_CTRL_STOP);
165	if (err < 0)
166		return err;
167
168	/* write register's data */
169	err = regmap_bulk_write(rx8581->regmap, RX8581_REG_SC,
170				buf, sizeof(buf));
171	if (err < 0)
172		return err;
173
174	/* get VLF and clear it */
175	err = regmap_update_bits(rx8581->regmap, RX8581_REG_FLAG,
176				 RX8581_FLAG_VLF, 0);
177	if (err < 0)
178		return err;
179
180	/* Restart the clock */
181	return regmap_update_bits(rx8581->regmap, RX8581_REG_CTRL,
182				 RX8581_CTRL_STOP, 0);
183}
184
185static const struct rtc_class_ops rx8581_rtc_ops = {
186	.read_time	= rx8581_rtc_read_time,
187	.set_time	= rx8581_rtc_set_time,
188};
189
190static int rx8571_nvram_read(void *priv, unsigned int offset, void *val,
191			     size_t bytes)
192{
193	struct rx8581 *rx8581 = priv;
194
195	return regmap_bulk_read(rx8581->regmap, RX8571_USER_RAM + offset,
196				val, bytes);
197}
198
199static int rx8571_nvram_write(void *priv, unsigned int offset, void *val,
200			      size_t bytes)
201{
202	struct rx8581 *rx8581 = priv;
203
204	return regmap_bulk_write(rx8581->regmap, RX8571_USER_RAM + offset,
205				 val, bytes);
206}
207
208static int rx85x1_nvram_read(void *priv, unsigned int offset, void *val,
209			     size_t bytes)
210{
211	struct rx8581 *rx8581 = priv;
212	unsigned int tmp_val;
213	int ret;
214
215	ret = regmap_read(rx8581->regmap, RX8581_REG_RAM, &tmp_val);
216	(*(unsigned char *)val) = (unsigned char) tmp_val;
217
218	return ret;
219}
220
221static int rx85x1_nvram_write(void *priv, unsigned int offset, void *val,
222			      size_t bytes)
223{
224	struct rx8581 *rx8581 = priv;
225	unsigned char tmp_val;
226
227	tmp_val = *((unsigned char *)val);
228	return regmap_write(rx8581->regmap, RX8581_REG_RAM,
229				(unsigned int)tmp_val);
230}
231
232static const struct rx85x1_config rx8581_config = {
233	.regmap = {
234		.reg_bits = 8,
235		.val_bits = 8,
236		.max_register = 0xf,
237	},
238	.num_nvram = 1
239};
240
241static const struct rx85x1_config rx8571_config = {
242	.regmap = {
243		.reg_bits = 8,
244		.val_bits = 8,
245		.max_register = 0x1f,
246	},
247	.num_nvram = 2
248};
249
250static int rx8581_probe(struct i2c_client *client)
251{
252	struct rx8581 *rx8581;
253	const struct rx85x1_config *config = &rx8581_config;
254	const void *data = of_device_get_match_data(&client->dev);
255	static struct nvmem_config nvmem_cfg[] = {
256		{
257			.name = "rx85x1-",
258			.word_size = 1,
259			.stride = 1,
260			.size = 1,
261			.reg_read = rx85x1_nvram_read,
262			.reg_write = rx85x1_nvram_write,
263		}, {
264			.name = "rx8571-",
265			.word_size = 1,
266			.stride = 1,
267			.size = RX8571_NVRAM_SIZE,
268			.reg_read = rx8571_nvram_read,
269			.reg_write = rx8571_nvram_write,
270		},
271	};
272	int ret, i;
273
274	dev_dbg(&client->dev, "%s\n", __func__);
275
276	if (data)
277		config = data;
278
279	rx8581 = devm_kzalloc(&client->dev, sizeof(struct rx8581), GFP_KERNEL);
280	if (!rx8581)
281		return -ENOMEM;
282
283	i2c_set_clientdata(client, rx8581);
284
285	rx8581->regmap = devm_regmap_init_i2c(client, &config->regmap);
286	if (IS_ERR(rx8581->regmap))
287		return PTR_ERR(rx8581->regmap);
288
289	rx8581->rtc = devm_rtc_allocate_device(&client->dev);
290	if (IS_ERR(rx8581->rtc))
291		return PTR_ERR(rx8581->rtc);
292
293	rx8581->rtc->ops = &rx8581_rtc_ops;
294	rx8581->rtc->range_min = RTC_TIMESTAMP_BEGIN_2000;
295	rx8581->rtc->range_max = RTC_TIMESTAMP_END_2099;
296	rx8581->rtc->start_secs = 0;
297	rx8581->rtc->set_start_time = true;
298
299	ret = devm_rtc_register_device(rx8581->rtc);
300
301	for (i = 0; i < config->num_nvram; i++) {
302		nvmem_cfg[i].priv = rx8581;
303		devm_rtc_nvmem_register(rx8581->rtc, &nvmem_cfg[i]);
304	}
305
306	return ret;
307}
308
309static const struct i2c_device_id rx8581_id[] = {
310	{ "rx8581", 0 },
311	{ }
312};
313MODULE_DEVICE_TABLE(i2c, rx8581_id);
314
315static const __maybe_unused struct of_device_id rx8581_of_match[] = {
316	{ .compatible = "epson,rx8571", .data = &rx8571_config },
317	{ .compatible = "epson,rx8581", .data = &rx8581_config },
318	{ /* sentinel */ }
319};
320MODULE_DEVICE_TABLE(of, rx8581_of_match);
321
322static struct i2c_driver rx8581_driver = {
323	.driver		= {
324		.name	= "rtc-rx8581",
325		.of_match_table = of_match_ptr(rx8581_of_match),
326	},
327	.probe		= rx8581_probe,
328	.id_table	= rx8581_id,
329};
330
331module_i2c_driver(rx8581_driver);
332
333MODULE_AUTHOR("Martyn Welch <martyn.welch@ge.com>");
334MODULE_DESCRIPTION("Epson RX-8571/RX-8581 RTC driver");
335MODULE_LICENSE("GPL");
336