rtc-rx8581.c

  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(regmap, RX8581_REG_FLAG, &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(regmap, RX8581_REG_FLAG,
 91					   data & ~RX8581_FLAG_UF);
 92			if (err < 0)
 93				return err;
 94		}
 95
 96		/* Now read time and date */
 97		err = regmap_bulk_read(regmap, RX8581_REG_SC, date,
 98				       sizeof(date));
 99		if (err < 0)
100			return err;
101
102		/* Check flag register */
103		err = regmap_read(regmap, RX8581_REG_FLAG, &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(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(regmap, RX8581_REG_SC, buf, sizeof(buf));
165	if (err < 0)
166		return err;
167
168	/* get VLF and clear it */
169	err = regmap_update_bits(regmap, RX8581_REG_FLAG, RX8581_FLAG_VLF, 0);
170	if (err < 0)
171		return err;
172
173	/* Restart the clock */
174	return regmap_update_bits(regmap, RX8581_REG_CTRL,
175				 RX8581_CTRL_STOP, 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(regmap, RX8571_USER_RAM + offset, val, 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(regmap, RX8571_USER_RAM + offset, val, 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(regmap, RX8581_REG_RAM, &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(regmap, RX8581_REG_RAM, (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(&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(regmap))
272		return PTR_ERR(regmap);
273
274	i2c_set_clientdata(client, regmap);
275
276	rtc = devm_rtc_allocate_device(&client->dev);
277	if (IS_ERR(rtc))
278		return PTR_ERR(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_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");