1/*
2 * rtc-isl12057 - Driver for Intersil ISL12057 I2C Real Time Clock
3 *
4 * Copyright (C) 2013, Arnaud EBALARD <arno@natisbad.org>
5 *
6 * This work is largely based on Intersil ISL1208 driver developed by
7 * Hebert Valerio Riedel <hvr@gnu.org>.
8 *
9 * Detailed datasheet on which this development is based is available here:
10 *
11 *  http://natisbad.org/NAS2/refs/ISL12057.pdf
12 *
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.
17 *
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.
22 */
23
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>
29#include <linux/of.h>
30#include <linux/of_device.h>
31#include <linux/regmap.h>
32
33#define DRV_NAME "rtc-isl12057"
34
35/* RTC section */
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_YR	0x06	/* Year */
45#define ISL12057_RTC_SEC_LEN	7
46
47/* Alarm 1 section */
48#define ISL12057_REG_A1_SC	0x07	/* Alarm 1 Seconds */
49#define ISL12057_REG_A1_MN	0x08	/* Alarm 1 Minutes */
50#define ISL12057_REG_A1_HR	0x09	/* Alarm 1 Hours */
51#define ISL12057_REG_A1_HR_PM	BIT(5)	/* AM/PM bit in 12h format */
52#define ISL12057_REG_A1_HR_MIL	BIT(6)	/* 24h/12h format */
53#define ISL12057_REG_A1_DWDT	0x0A	/* Alarm 1 Date / Day of the week */
54#define ISL12057_REG_A1_DWDT_B	BIT(6)	/* DW / DT selection bit */
55#define ISL12057_A1_SEC_LEN	4
56
57/* Alarm 2 section */
58#define ISL12057_REG_A2_MN	0x0B	/* Alarm 2 Minutes */
59#define ISL12057_REG_A2_HR	0x0C	/* Alarm 2 Hours */
60#define ISL12057_REG_A2_DWDT	0x0D	/* Alarm 2 Date / Day of the week */
61#define ISL12057_A2_SEC_LEN	3
62
63/* Control/Status registers */
64#define ISL12057_REG_INT	0x0E
65#define ISL12057_REG_INT_A1IE	BIT(0)	/* Alarm 1 interrupt enable bit */
66#define ISL12057_REG_INT_A2IE	BIT(1)	/* Alarm 2 interrupt enable bit */
67#define ISL12057_REG_INT_INTCN	BIT(2)	/* Interrupt control enable bit */
68#define ISL12057_REG_INT_RS1	BIT(3)	/* Freq out control bit 1 */
69#define ISL12057_REG_INT_RS2	BIT(4)	/* Freq out control bit 2 */
70#define ISL12057_REG_INT_EOSC	BIT(7)	/* Oscillator enable bit */
71
72#define ISL12057_REG_SR		0x0F
73#define ISL12057_REG_SR_A1F	BIT(0)	/* Alarm 1 interrupt bit */
74#define ISL12057_REG_SR_A2F	BIT(1)	/* Alarm 2 interrupt bit */
75#define ISL12057_REG_SR_OSF	BIT(7)	/* Oscillator failure bit */
76
77/* Register memory map length */
78#define ISL12057_MEM_MAP_LEN	0x10
79
80struct isl12057_rtc_data {
81	struct regmap *regmap;
82	struct mutex lock;
83};
84
85static void isl12057_rtc_regs_to_tm(struct rtc_time *tm, u8 *regs)
86{
87	tm->tm_sec = bcd2bin(regs[ISL12057_REG_RTC_SC]);
88	tm->tm_min = bcd2bin(regs[ISL12057_REG_RTC_MN]);
89
90	if (regs[ISL12057_REG_RTC_HR] & ISL12057_REG_RTC_HR_MIL) { /* AM/PM */
91		tm->tm_hour = bcd2bin(regs[ISL12057_REG_RTC_HR] & 0x0f);
92		if (regs[ISL12057_REG_RTC_HR] & ISL12057_REG_RTC_HR_PM)
93			tm->tm_hour += 12;
94	} else {					    /* 24 hour mode */
95		tm->tm_hour = bcd2bin(regs[ISL12057_REG_RTC_HR] & 0x3f);
96	}
97
98	tm->tm_mday = bcd2bin(regs[ISL12057_REG_RTC_DT]);
99	tm->tm_wday = bcd2bin(regs[ISL12057_REG_RTC_DW]) - 1; /* starts at 1 */
100	tm->tm_mon  = bcd2bin(regs[ISL12057_REG_RTC_MO]) - 1; /* starts at 1 */
101	tm->tm_year = bcd2bin(regs[ISL12057_REG_RTC_YR]) + 100;
102}
103
104static int isl12057_rtc_tm_to_regs(u8 *regs, struct rtc_time *tm)
105{
106	/*
107	 * The clock has an 8 bit wide bcd-coded register for the year.
108	 * tm_year is an offset from 1900 and we are interested in the
109	 * 2000-2099 range, so any value less than 100 is invalid.
110	 */
111	if (tm->tm_year < 100)
112		return -EINVAL;
113
114	regs[ISL12057_REG_RTC_SC] = bin2bcd(tm->tm_sec);
115	regs[ISL12057_REG_RTC_MN] = bin2bcd(tm->tm_min);
116	regs[ISL12057_REG_RTC_HR] = bin2bcd(tm->tm_hour); /* 24-hour format */
117	regs[ISL12057_REG_RTC_DT] = bin2bcd(tm->tm_mday);
118	regs[ISL12057_REG_RTC_MO] = bin2bcd(tm->tm_mon + 1);
119	regs[ISL12057_REG_RTC_YR] = bin2bcd(tm->tm_year - 100);
120	regs[ISL12057_REG_RTC_DW] = bin2bcd(tm->tm_wday + 1);
121
122	return 0;
123}
124
125/*
126 * Try and match register bits w/ fixed null values to see whether we
127 * are dealing with an ISL12057. Note: this function is called early
128 * during init and hence does need mutex protection.
129 */
130static int isl12057_i2c_validate_chip(struct regmap *regmap)
131{
132	u8 regs[ISL12057_MEM_MAP_LEN];
133	static const u8 mask[ISL12057_MEM_MAP_LEN] = { 0x80, 0x80, 0x80, 0xf8,
134						       0xc0, 0x60, 0x00, 0x00,
135						       0x00, 0x00, 0x00, 0x00,
136						       0x00, 0x00, 0x60, 0x7c };
137	int ret, i;
138
139	ret = regmap_bulk_read(regmap, 0, regs, ISL12057_MEM_MAP_LEN);
140	if (ret)
141		return ret;
142
143	for (i = 0; i < ISL12057_MEM_MAP_LEN; ++i) {
144		if (regs[i] & mask[i])	/* check if bits are cleared */
145			return -ENODEV;
146	}
147
148	return 0;
149}
150
151static int isl12057_rtc_read_time(struct device *dev, struct rtc_time *tm)
152{
153	struct isl12057_rtc_data *data = dev_get_drvdata(dev);
154	u8 regs[ISL12057_RTC_SEC_LEN];
155	int ret;
156
157	mutex_lock(&data->lock);
158	ret = regmap_bulk_read(data->regmap, ISL12057_REG_RTC_SC, regs,
159			       ISL12057_RTC_SEC_LEN);
160	mutex_unlock(&data->lock);
161
162	if (ret) {
163		dev_err(dev, "%s: RTC read failed\n", __func__);
164		return ret;
165	}
166
167	isl12057_rtc_regs_to_tm(tm, regs);
168
169	return rtc_valid_tm(tm);
170}
171
172static int isl12057_rtc_set_time(struct device *dev, struct rtc_time *tm)
173{
174	struct isl12057_rtc_data *data = dev_get_drvdata(dev);
175	u8 regs[ISL12057_RTC_SEC_LEN];
176	int ret;
177
178	ret = isl12057_rtc_tm_to_regs(regs, tm);
179	if (ret)
180		return ret;
181
182	mutex_lock(&data->lock);
183	ret = regmap_bulk_write(data->regmap, ISL12057_REG_RTC_SC, regs,
184				ISL12057_RTC_SEC_LEN);
185	mutex_unlock(&data->lock);
186
187	if (ret)
188		dev_err(dev, "%s: RTC write failed\n", __func__);
189
190	return ret;
191}
192
193/*
194 * Check current RTC status and enable/disable what needs to be. Return 0 if
195 * everything went ok and a negative value upon error. Note: this function
196 * is called early during init and hence does need mutex protection.
197 */
198static int isl12057_check_rtc_status(struct device *dev, struct regmap *regmap)
199{
200	int ret;
201
202	/* Enable oscillator if not already running */
203	ret = regmap_update_bits(regmap, ISL12057_REG_INT,
204				 ISL12057_REG_INT_EOSC, 0);
205	if (ret < 0) {
206		dev_err(dev, "Unable to enable oscillator\n");
207		return ret;
208	}
209
210	/* Clear oscillator failure bit if needed */
211	ret = regmap_update_bits(regmap, ISL12057_REG_SR,
212				 ISL12057_REG_SR_OSF, 0);
213	if (ret < 0) {
214		dev_err(dev, "Unable to clear oscillator failure bit\n");
215		return ret;
216	}
217
218	/* Clear alarm bit if needed */
219	ret = regmap_update_bits(regmap, ISL12057_REG_SR,
220				 ISL12057_REG_SR_A1F, 0);
221	if (ret < 0) {
222		dev_err(dev, "Unable to clear alarm bit\n");
223		return ret;
224	}
225
226	return 0;
227}
228
229static const struct rtc_class_ops rtc_ops = {
230	.read_time = isl12057_rtc_read_time,
231	.set_time = isl12057_rtc_set_time,
232};
233
234static struct regmap_config isl12057_rtc_regmap_config = {
235	.reg_bits = 8,
236	.val_bits = 8,
237};
238
239static int isl12057_probe(struct i2c_client *client,
240			  const struct i2c_device_id *id)
241{
242	struct device *dev = &client->dev;
243	struct isl12057_rtc_data *data;
244	struct rtc_device *rtc;
245	struct regmap *regmap;
246	int ret;
247
248	if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C |
249				     I2C_FUNC_SMBUS_BYTE_DATA |
250				     I2C_FUNC_SMBUS_I2C_BLOCK))
251		return -ENODEV;
252
253	regmap = devm_regmap_init_i2c(client, &isl12057_rtc_regmap_config);
254	if (IS_ERR(regmap)) {
255		ret = PTR_ERR(regmap);
256		dev_err(dev, "regmap allocation failed: %d\n", ret);
257		return ret;
258	}
259
260	ret = isl12057_i2c_validate_chip(regmap);
261	if (ret)
262		return ret;
263
264	ret = isl12057_check_rtc_status(dev, regmap);
265	if (ret)
266		return ret;
267
268	data = devm_kzalloc(dev, sizeof(*data), GFP_KERNEL);
269	if (!data)
270		return -ENOMEM;
271
272	mutex_init(&data->lock);
273	data->regmap = regmap;
274	dev_set_drvdata(dev, data);
275
276	rtc = devm_rtc_device_register(dev, DRV_NAME, &rtc_ops, THIS_MODULE);
277	return PTR_ERR_OR_ZERO(rtc);
278}
279
280#ifdef CONFIG_OF
281static const struct of_device_id isl12057_dt_match[] = {
282	{ .compatible = "isl,isl12057" },
283	{ },
284};
285#endif
286
287static const struct i2c_device_id isl12057_id[] = {
288	{ "isl12057", 0 },
289	{ }
290};
291MODULE_DEVICE_TABLE(i2c, isl12057_id);
292
293static struct i2c_driver isl12057_driver = {
294	.driver = {
295		.name = DRV_NAME,
296		.owner = THIS_MODULE,
297		.of_match_table = of_match_ptr(isl12057_dt_match),
298	},
299	.probe	  = isl12057_probe,
300	.id_table = isl12057_id,
301};
302module_i2c_driver(isl12057_driver);
303
304MODULE_AUTHOR("Arnaud EBALARD <arno@natisbad.org>");
305MODULE_DESCRIPTION("Intersil ISL12057 RTC driver");
306MODULE_LICENSE("GPL");
307