1/*
  2 * An I2C driver for the PCF85063 RTC
  3 * Copyright 2014 Rose Technology
  4 *
  5 * Author: Søren Andersen <san@rosetechnology.dk>
  6 * Maintainers: http://www.nslu2-linux.org/
  7 *
  8 * based on the other drivers in this same directory.
  9 *
 10 * This program is free software; you can redistribute it and/or modify
 11 * it under the terms of the GNU General Public License version 2 as
 12 * published by the Free Software Foundation.
 13 */
 14#include <linux/i2c.h>
 15#include <linux/bcd.h>
 16#include <linux/rtc.h>
 17#include <linux/module.h>
 18
 19#define PCF85063_REG_CTRL1		0x00 /* status */
 20#define PCF85063_REG_CTRL1_STOP		BIT(5)
 21#define PCF85063_REG_CTRL2		0x01
 22
 23#define PCF85063_REG_SC			0x04 /* datetime */
 24#define PCF85063_REG_SC_OS		0x80
 25#define PCF85063_REG_MN			0x05
 26#define PCF85063_REG_HR			0x06
 27#define PCF85063_REG_DM			0x07
 28#define PCF85063_REG_DW			0x08
 29#define PCF85063_REG_MO			0x09
 30#define PCF85063_REG_YR			0x0A
 31
 32static struct i2c_driver pcf85063_driver;
 33
 34static int pcf85063_stop_clock(struct i2c_client *client, u8 *ctrl1)
 35{
 36	s32 ret;
 37
 38	ret = i2c_smbus_read_byte_data(client, PCF85063_REG_CTRL1);
 39	if (ret < 0) {
 40		dev_err(&client->dev, "Failing to stop the clock\n");
 41		return -EIO;
 42	}
 43
 44	/* stop the clock */
 45	ret |= PCF85063_REG_CTRL1_STOP;
 46
 47	ret = i2c_smbus_write_byte_data(client, PCF85063_REG_CTRL1, ret);
 48	if (ret < 0) {
 49		dev_err(&client->dev, "Failing to stop the clock\n");
 50		return -EIO;
 51	}
 52
 53	*ctrl1 = ret;
 54
 55	return 0;
 56}
 57
 58/*
 59 * In the routines that deal directly with the pcf85063 hardware, we use
 60 * rtc_time -- month 0-11, hour 0-23, yr = calendar year-epoch.
 61 */
 62static int pcf85063_get_datetime(struct i2c_client *client, struct rtc_time *tm)
 63{
 64	int rc;
 65	u8 regs[7];
 66
 67	/*
 68	 * while reading, the time/date registers are blocked and not updated
 69	 * anymore until the access is finished. To not lose a second
 70	 * event, the access must be finished within one second. So, read all
 71	 * time/date registers in one turn.
 72	 */
 73	rc = i2c_smbus_read_i2c_block_data(client, PCF85063_REG_SC,
 74					   sizeof(regs), regs);
 75	if (rc != sizeof(regs)) {
 76		dev_err(&client->dev, "date/time register read error\n");
 77		return -EIO;
 78	}
 79
 80	/* if the clock has lost its power it makes no sense to use its time */
 81	if (regs[0] & PCF85063_REG_SC_OS) {
 82		dev_warn(&client->dev, "Power loss detected, invalid time\n");
 83		return -EINVAL;
 84	}
 85
 86	tm->tm_sec = bcd2bin(regs[0] & 0x7F);
 87	tm->tm_min = bcd2bin(regs[1] & 0x7F);
 88	tm->tm_hour = bcd2bin(regs[2] & 0x3F); /* rtc hr 0-23 */
 89	tm->tm_mday = bcd2bin(regs[3] & 0x3F);
 90	tm->tm_wday = regs[4] & 0x07;
 91	tm->tm_mon = bcd2bin(regs[5] & 0x1F) - 1; /* rtc mn 1-12 */
 92	tm->tm_year = bcd2bin(regs[6]);
 93	if (tm->tm_year < 70)
 94		tm->tm_year += 100;	/* assume we are in 1970...2069 */
 95
 96	return rtc_valid_tm(tm);
 97}
 98
 99static int pcf85063_set_datetime(struct i2c_client *client, struct rtc_time *tm)
100{
101	int rc;
102	u8 regs[8];
103
104	/*
105	 * to accurately set the time, reset the divider chain and keep it in
106	 * reset state until all time/date registers are written
107	 */
108	rc = pcf85063_stop_clock(client, &regs[7]);
109	if (rc != 0)
110		return rc;
111
112	/* hours, minutes and seconds */
113	regs[0] = bin2bcd(tm->tm_sec) & 0x7F; /* clear OS flag */
114
115	regs[1] = bin2bcd(tm->tm_min);
116	regs[2] = bin2bcd(tm->tm_hour);
117
118	/* Day of month, 1 - 31 */
119	regs[3] = bin2bcd(tm->tm_mday);
120
121	/* Day, 0 - 6 */
122	regs[4] = tm->tm_wday & 0x07;
123
124	/* month, 1 - 12 */
125	regs[5] = bin2bcd(tm->tm_mon + 1);
126
127	/* year and century */
128	regs[6] = bin2bcd(tm->tm_year % 100);
129
130	/*
131	 * after all time/date registers are written, let the 'address auto
132	 * increment' feature wrap around and write register CTRL1 to re-enable
133	 * the clock divider chain again
134	 */
135	regs[7] &= ~PCF85063_REG_CTRL1_STOP;
136
137	/* write all registers at once */
138	rc = i2c_smbus_write_i2c_block_data(client, PCF85063_REG_SC,
139					    sizeof(regs), regs);
140	if (rc < 0) {
141		dev_err(&client->dev, "date/time register write error\n");
142		return rc;
143	}
144
145	return 0;
146}
147
148static int pcf85063_rtc_read_time(struct device *dev, struct rtc_time *tm)
149{
150	return pcf85063_get_datetime(to_i2c_client(dev), tm);
151}
152
153static int pcf85063_rtc_set_time(struct device *dev, struct rtc_time *tm)
154{
155	return pcf85063_set_datetime(to_i2c_client(dev), tm);
156}
157
158static const struct rtc_class_ops pcf85063_rtc_ops = {
159	.read_time	= pcf85063_rtc_read_time,
160	.set_time	= pcf85063_rtc_set_time
161};
162
163static int pcf85063_probe(struct i2c_client *client,
164				const struct i2c_device_id *id)
165{
166	struct rtc_device *rtc;
167
168	dev_dbg(&client->dev, "%s\n", __func__);
169
170	if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C))
171		return -ENODEV;
172
173	rtc = devm_rtc_device_register(&client->dev,
174				       pcf85063_driver.driver.name,
175				       &pcf85063_rtc_ops, THIS_MODULE);
176
177	return PTR_ERR_OR_ZERO(rtc);
178}
179
180static const struct i2c_device_id pcf85063_id[] = {
181	{ "pcf85063", 0 },
182	{ }
183};
184MODULE_DEVICE_TABLE(i2c, pcf85063_id);
185
186#ifdef CONFIG_OF
187static const struct of_device_id pcf85063_of_match[] = {
188	{ .compatible = "nxp,pcf85063" },
189	{}
190};
191MODULE_DEVICE_TABLE(of, pcf85063_of_match);
192#endif
193
194static struct i2c_driver pcf85063_driver = {
195	.driver		= {
196		.name	= "rtc-pcf85063",
197		.of_match_table = of_match_ptr(pcf85063_of_match),
198	},
199	.probe		= pcf85063_probe,
200	.id_table	= pcf85063_id,
201};
202
203module_i2c_driver(pcf85063_driver);
204
205MODULE_AUTHOR("Søren Andersen <san@rosetechnology.dk>");
206MODULE_DESCRIPTION("PCF85063 RTC driver");
207MODULE_LICENSE("GPL");