2 * rtc-isl12057 - Driver for Intersil ISL12057 I2C Real Time Clock
4 * Copyright (C) 2013, Arnaud EBALARD <arno@natisbad.org>
6 * This work is largely based on Intersil ISL1208 driver developed by
7 * Hebert Valerio Riedel <hvr@gnu.org>.
9 * Detailed datasheet on which this development is based is available here:
11 * http://natisbad.org/NAS2/refs/ISL12057.pdf
13 * This program is free software; you can redistribute it and/or modify
14 * it under the terms of the GNU General Public License as published by
15 * the Free Software Foundation; either version 2 of the License, or
16 * (at your option) any later version.
18 * This program is distributed in the hope that it will be useful,
19 * but WITHOUT ANY WARRANTY; without even the implied warranty of
20 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
21 * GNU General Public License for more details.
24 #include <linux/module.h>
25 #include <linux/mutex.h>
26 #include <linux/rtc.h>
27 #include <linux/i2c.h>
28 #include <linux/bcd.h>
30 #include <linux/of_device.h>
31 #include <linux/regmap.h>
33 #define DRV_NAME "rtc-isl12057"
36 #define ISL12057_REG_RTC_SC 0x00 /* Seconds */
37 #define ISL12057_REG_RTC_MN 0x01 /* Minutes */
38 #define ISL12057_REG_RTC_HR 0x02 /* Hours */
39 #define ISL12057_REG_RTC_HR_PM BIT(5) /* AM/PM bit in 12h format */
40 #define ISL12057_REG_RTC_HR_MIL BIT(6) /* 24h/12h format */
41 #define ISL12057_REG_RTC_DW 0x03 /* Day of the Week */
42 #define ISL12057_REG_RTC_DT 0x04 /* Date */
43 #define ISL12057_REG_RTC_MO 0x05 /* Month */
44 #define ISL12057_REG_RTC_MO_CEN BIT(7) /* Century bit */
45 #define ISL12057_REG_RTC_YR 0x06 /* Year */
46 #define ISL12057_RTC_SEC_LEN 7
49 #define ISL12057_REG_A1_SC 0x07 /* Alarm 1 Seconds */
50 #define ISL12057_REG_A1_MN 0x08 /* Alarm 1 Minutes */
51 #define ISL12057_REG_A1_HR 0x09 /* Alarm 1 Hours */
52 #define ISL12057_REG_A1_HR_PM BIT(5) /* AM/PM bit in 12h format */
53 #define ISL12057_REG_A1_HR_MIL BIT(6) /* 24h/12h format */
54 #define ISL12057_REG_A1_DWDT 0x0A /* Alarm 1 Date / Day of the week */
55 #define ISL12057_REG_A1_DWDT_B BIT(6) /* DW / DT selection bit */
56 #define ISL12057_A1_SEC_LEN 4
59 #define ISL12057_REG_A2_MN 0x0B /* Alarm 2 Minutes */
60 #define ISL12057_REG_A2_HR 0x0C /* Alarm 2 Hours */
61 #define ISL12057_REG_A2_DWDT 0x0D /* Alarm 2 Date / Day of the week */
62 #define ISL12057_A2_SEC_LEN 3
64 /* Control/Status registers */
65 #define ISL12057_REG_INT 0x0E
66 #define ISL12057_REG_INT_A1IE BIT(0) /* Alarm 1 interrupt enable bit */
67 #define ISL12057_REG_INT_A2IE BIT(1) /* Alarm 2 interrupt enable bit */
68 #define ISL12057_REG_INT_INTCN BIT(2) /* Interrupt control enable bit */
69 #define ISL12057_REG_INT_RS1 BIT(3) /* Freq out control bit 1 */
70 #define ISL12057_REG_INT_RS2 BIT(4) /* Freq out control bit 2 */
71 #define ISL12057_REG_INT_EOSC BIT(7) /* Oscillator enable bit */
73 #define ISL12057_REG_SR 0x0F
74 #define ISL12057_REG_SR_A1F BIT(0) /* Alarm 1 interrupt bit */
75 #define ISL12057_REG_SR_A2F BIT(1) /* Alarm 2 interrupt bit */
76 #define ISL12057_REG_SR_OSF BIT(7) /* Oscillator failure bit */
78 /* Register memory map length */
79 #define ISL12057_MEM_MAP_LEN 0x10
81 struct isl12057_rtc_data {
82 struct regmap *regmap;
86 static void isl12057_rtc_regs_to_tm(struct rtc_time *tm, u8 *regs)
88 tm->tm_sec = bcd2bin(regs[ISL12057_REG_RTC_SC]);
89 tm->tm_min = bcd2bin(regs[ISL12057_REG_RTC_MN]);
91 if (regs[ISL12057_REG_RTC_HR] & ISL12057_REG_RTC_HR_MIL) { /* AM/PM */
92 tm->tm_hour = bcd2bin(regs[ISL12057_REG_RTC_HR] & 0x1f);
93 if (regs[ISL12057_REG_RTC_HR] & ISL12057_REG_RTC_HR_PM)
95 } else { /* 24 hour mode */
96 tm->tm_hour = bcd2bin(regs[ISL12057_REG_RTC_HR] & 0x3f);
99 tm->tm_mday = bcd2bin(regs[ISL12057_REG_RTC_DT]);
100 tm->tm_wday = bcd2bin(regs[ISL12057_REG_RTC_DW]) - 1; /* starts at 1 */
101 tm->tm_mon = bcd2bin(regs[ISL12057_REG_RTC_MO] & 0x1f) - 1; /* ditto */
102 tm->tm_year = bcd2bin(regs[ISL12057_REG_RTC_YR]) + 100;
104 /* Check if years register has overflown from 99 to 00 */
105 if (regs[ISL12057_REG_RTC_MO] & ISL12057_REG_RTC_MO_CEN)
109 static int isl12057_rtc_tm_to_regs(u8 *regs, struct rtc_time *tm)
114 * The clock has an 8 bit wide bcd-coded register for the year.
115 * It also has a century bit encoded in MO flag which provides
116 * information about overflow of year register from 99 to 00.
117 * tm_year is an offset from 1900 and we are interested in the
118 * 2000-2199 range, so any value less than 100 or larger than
121 if (tm->tm_year < 100 || tm->tm_year > 299)
124 century_bit = (tm->tm_year > 199) ? ISL12057_REG_RTC_MO_CEN : 0;
126 regs[ISL12057_REG_RTC_SC] = bin2bcd(tm->tm_sec);
127 regs[ISL12057_REG_RTC_MN] = bin2bcd(tm->tm_min);
128 regs[ISL12057_REG_RTC_HR] = bin2bcd(tm->tm_hour); /* 24-hour format */
129 regs[ISL12057_REG_RTC_DT] = bin2bcd(tm->tm_mday);
130 regs[ISL12057_REG_RTC_MO] = bin2bcd(tm->tm_mon + 1) | century_bit;
131 regs[ISL12057_REG_RTC_YR] = bin2bcd(tm->tm_year % 100);
132 regs[ISL12057_REG_RTC_DW] = bin2bcd(tm->tm_wday + 1);
138 * Try and match register bits w/ fixed null values to see whether we
139 * are dealing with an ISL12057. Note: this function is called early
140 * during init and hence does need mutex protection.
142 static int isl12057_i2c_validate_chip(struct regmap *regmap)
144 u8 regs[ISL12057_MEM_MAP_LEN];
145 static const u8 mask[ISL12057_MEM_MAP_LEN] = { 0x80, 0x80, 0x80, 0xf8,
146 0xc0, 0x60, 0x00, 0x00,
147 0x00, 0x00, 0x00, 0x00,
148 0x00, 0x00, 0x60, 0x7c };
151 ret = regmap_bulk_read(regmap, 0, regs, ISL12057_MEM_MAP_LEN);
155 for (i = 0; i < ISL12057_MEM_MAP_LEN; ++i) {
156 if (regs[i] & mask[i]) /* check if bits are cleared */
163 static int isl12057_rtc_read_time(struct device *dev, struct rtc_time *tm)
165 struct isl12057_rtc_data *data = dev_get_drvdata(dev);
166 u8 regs[ISL12057_RTC_SEC_LEN];
170 mutex_lock(&data->lock);
171 ret = regmap_read(data->regmap, ISL12057_REG_SR, &sr);
173 dev_err(dev, "%s: unable to read oscillator status flag\n",
177 if (sr & ISL12057_REG_SR_OSF) {
183 ret = regmap_bulk_read(data->regmap, ISL12057_REG_RTC_SC, regs,
184 ISL12057_RTC_SEC_LEN);
186 dev_err(dev, "%s: unable to read RTC time\n", __func__);
189 mutex_unlock(&data->lock);
194 isl12057_rtc_regs_to_tm(tm, regs);
196 return rtc_valid_tm(tm);
199 static int isl12057_rtc_set_time(struct device *dev, struct rtc_time *tm)
201 struct isl12057_rtc_data *data = dev_get_drvdata(dev);
202 u8 regs[ISL12057_RTC_SEC_LEN];
205 ret = isl12057_rtc_tm_to_regs(regs, tm);
209 mutex_lock(&data->lock);
210 ret = regmap_bulk_write(data->regmap, ISL12057_REG_RTC_SC, regs,
211 ISL12057_RTC_SEC_LEN);
213 dev_err(dev, "%s: writing RTC time failed\n", __func__);
218 * Now that RTC time has been updated, let's clear oscillator
219 * failure flag, if needed.
221 ret = regmap_update_bits(data->regmap, ISL12057_REG_SR,
222 ISL12057_REG_SR_OSF, 0);
224 dev_err(dev, "Unable to clear oscillator failure bit\n");
227 mutex_unlock(&data->lock);
233 * Check current RTC status and enable/disable what needs to be. Return 0 if
234 * everything went ok and a negative value upon error. Note: this function
235 * is called early during init and hence does need mutex protection.
237 static int isl12057_check_rtc_status(struct device *dev, struct regmap *regmap)
241 /* Enable oscillator if not already running */
242 ret = regmap_update_bits(regmap, ISL12057_REG_INT,
243 ISL12057_REG_INT_EOSC, 0);
245 dev_err(dev, "Unable to enable oscillator\n");
249 /* Clear alarm bit if needed */
250 ret = regmap_update_bits(regmap, ISL12057_REG_SR,
251 ISL12057_REG_SR_A1F, 0);
253 dev_err(dev, "Unable to clear alarm bit\n");
260 static const struct rtc_class_ops rtc_ops = {
261 .read_time = isl12057_rtc_read_time,
262 .set_time = isl12057_rtc_set_time,
265 static struct regmap_config isl12057_rtc_regmap_config = {
270 static int isl12057_probe(struct i2c_client *client,
271 const struct i2c_device_id *id)
273 struct device *dev = &client->dev;
274 struct isl12057_rtc_data *data;
275 struct rtc_device *rtc;
276 struct regmap *regmap;
279 if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C |
280 I2C_FUNC_SMBUS_BYTE_DATA |
281 I2C_FUNC_SMBUS_I2C_BLOCK))
284 regmap = devm_regmap_init_i2c(client, &isl12057_rtc_regmap_config);
285 if (IS_ERR(regmap)) {
286 ret = PTR_ERR(regmap);
287 dev_err(dev, "regmap allocation failed: %d\n", ret);
291 ret = isl12057_i2c_validate_chip(regmap);
295 ret = isl12057_check_rtc_status(dev, regmap);
299 data = devm_kzalloc(dev, sizeof(*data), GFP_KERNEL);
303 mutex_init(&data->lock);
304 data->regmap = regmap;
305 dev_set_drvdata(dev, data);
307 rtc = devm_rtc_device_register(dev, DRV_NAME, &rtc_ops, THIS_MODULE);
308 return PTR_ERR_OR_ZERO(rtc);
312 static const struct of_device_id isl12057_dt_match[] = {
313 { .compatible = "isl,isl12057" },
318 static const struct i2c_device_id isl12057_id[] = {
322 MODULE_DEVICE_TABLE(i2c, isl12057_id);
324 static struct i2c_driver isl12057_driver = {
327 .owner = THIS_MODULE,
328 .of_match_table = of_match_ptr(isl12057_dt_match),
330 .probe = isl12057_probe,
331 .id_table = isl12057_id,
333 module_i2c_driver(isl12057_driver);
335 MODULE_AUTHOR("Arnaud EBALARD <arno@natisbad.org>");
336 MODULE_DESCRIPTION("Intersil ISL12057 RTC driver");
337 MODULE_LICENSE("GPL");