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/*
 20 * Information for this driver was pulled from the following datasheets.
 21 *
 22 *  http://www.nxp.com/documents/data_sheet/PCF85063A.pdf
 23 *  http://www.nxp.com/documents/data_sheet/PCF85063TP.pdf
 24 *
 25 *  PCF85063A -- Rev. 6 — 18 November 2015
 26 *  PCF85063TP -- Rev. 4 — 6 May 2015
 27*/
 28
 29#define PCF85063_REG_CTRL1		0x00 /* status */
 30#define PCF85063_REG_CTRL1_STOP		BIT(5)
 31#define PCF85063_REG_CTRL2		0x01
 32
 33#define PCF85063_REG_SC			0x04 /* datetime */
 34#define PCF85063_REG_SC_OS		0x80
 35#define PCF85063_REG_MN			0x05
 36#define PCF85063_REG_HR			0x06
 37#define PCF85063_REG_DM			0x07
 38#define PCF85063_REG_DW			0x08
 39#define PCF85063_REG_MO			0x09
 40#define PCF85063_REG_YR			0x0A
 41
 42static struct i2c_driver pcf85063_driver;
 43
 44static int pcf85063_stop_clock(struct i2c_client *client, u8 *ctrl1)
 45{
 46	s32 ret;
 47
 48	ret = i2c_smbus_read_byte_data(client, PCF85063_REG_CTRL1);
 49	if (ret < 0) {
 50		dev_err(&client->dev, "Failing to stop the clock\n");
 51		return -EIO;
 52	}
 53
 54	/* stop the clock */
 55	ret |= PCF85063_REG_CTRL1_STOP;
 56
 57	ret = i2c_smbus_write_byte_data(client, PCF85063_REG_CTRL1, ret);
 58	if (ret < 0) {
 59		dev_err(&client->dev, "Failing to stop the clock\n");
 60		return -EIO;
 61	}
 62
 63	*ctrl1 = ret;
 64
 65	return 0;
 66}
 67
 68static int pcf85063_start_clock(struct i2c_client *client, u8 ctrl1)
 69{
 70	s32 ret;
 71
 72	/* start the clock */
 73	ctrl1 &= PCF85063_REG_CTRL1_STOP;
 74
 75	ret = i2c_smbus_write_byte_data(client, PCF85063_REG_CTRL1, ctrl1);
 76	if (ret < 0) {
 77		dev_err(&client->dev, "Failing to start the clock\n");
 78		return -EIO;
 79	}
 80
 81	return 0;
 82}
 83
 84static int pcf85063_get_datetime(struct i2c_client *client, struct rtc_time *tm)
 85{
 86	int rc;
 87	u8 regs[7];
 88
 89	/*
 90	 * while reading, the time/date registers are blocked and not updated
 91	 * anymore until the access is finished. To not lose a second
 92	 * event, the access must be finished within one second. So, read all
 93	 * time/date registers in one turn.
 94	 */
 95	rc = i2c_smbus_read_i2c_block_data(client, PCF85063_REG_SC,
 96					   sizeof(regs), regs);
 97	if (rc != sizeof(regs)) {
 98		dev_err(&client->dev, "date/time register read error\n");
 99		return -EIO;
100	}
101
102	/* if the clock has lost its power it makes no sense to use its time */
103	if (regs[0] & PCF85063_REG_SC_OS) {
104		dev_warn(&client->dev, "Power loss detected, invalid time\n");
105		return -EINVAL;
106	}
107
108	tm->tm_sec = bcd2bin(regs[0] & 0x7F);
109	tm->tm_min = bcd2bin(regs[1] & 0x7F);
110	tm->tm_hour = bcd2bin(regs[2] & 0x3F); /* rtc hr 0-23 */
111	tm->tm_mday = bcd2bin(regs[3] & 0x3F);
112	tm->tm_wday = regs[4] & 0x07;
113	tm->tm_mon = bcd2bin(regs[5] & 0x1F) - 1; /* rtc mn 1-12 */
114	tm->tm_year = bcd2bin(regs[6]);
115	tm->tm_year += 100;
116
117	return rtc_valid_tm(tm);
118}
119
120static int pcf85063_set_datetime(struct i2c_client *client, struct rtc_time *tm)
121{
122	int rc;
123	u8 regs[7];
124	u8 ctrl1;
125
126	if ((tm->tm_year < 100) || (tm->tm_year > 199))
127		return -EINVAL;
128
129	/*
130	 * to accurately set the time, reset the divider chain and keep it in
131	 * reset state until all time/date registers are written
132	 */
133	rc = pcf85063_stop_clock(client, &ctrl1);
134	if (rc != 0)
135		return rc;
136
137	/* hours, minutes and seconds */
138	regs[0] = bin2bcd(tm->tm_sec) & 0x7F; /* clear OS flag */
139
140	regs[1] = bin2bcd(tm->tm_min);
141	regs[2] = bin2bcd(tm->tm_hour);
142
143	/* Day of month, 1 - 31 */
144	regs[3] = bin2bcd(tm->tm_mday);
145
146	/* Day, 0 - 6 */
147	regs[4] = tm->tm_wday & 0x07;
148
149	/* month, 1 - 12 */
150	regs[5] = bin2bcd(tm->tm_mon + 1);
151
152	/* year and century */
153	regs[6] = bin2bcd(tm->tm_year - 100);
154
155	/* write all registers at once */
156	rc = i2c_smbus_write_i2c_block_data(client, PCF85063_REG_SC,
157					    sizeof(regs), regs);
158	if (rc < 0) {
159		dev_err(&client->dev, "date/time register write error\n");
160		return rc;
161	}
162
163	/*
164	 * Write the control register as a separate action since the size of
165	 * the register space is different between the PCF85063TP and
166	 * PCF85063A devices.  The rollover point can not be used.
167	 */
168	rc = pcf85063_start_clock(client, ctrl1);
169	if (rc != 0)
170		return rc;
171
172	return 0;
173}
174
175static int pcf85063_rtc_read_time(struct device *dev, struct rtc_time *tm)
176{
177	return pcf85063_get_datetime(to_i2c_client(dev), tm);
178}
179
180static int pcf85063_rtc_set_time(struct device *dev, struct rtc_time *tm)
181{
182	return pcf85063_set_datetime(to_i2c_client(dev), tm);
183}
184
185static const struct rtc_class_ops pcf85063_rtc_ops = {
186	.read_time	= pcf85063_rtc_read_time,
187	.set_time	= pcf85063_rtc_set_time
188};
189
190static int pcf85063_probe(struct i2c_client *client,
191				const struct i2c_device_id *id)
192{
193	struct rtc_device *rtc;
194	int err;
195
196	dev_dbg(&client->dev, "%s\n", __func__);
197
198	if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C))
199		return -ENODEV;
200
201	err = i2c_smbus_read_byte_data(client, PCF85063_REG_CTRL1);
202	if (err < 0) {
203		dev_err(&client->dev, "RTC chip is not present\n");
204		return err;
205	}
206
207	rtc = devm_rtc_device_register(&client->dev,
208				       pcf85063_driver.driver.name,
209				       &pcf85063_rtc_ops, THIS_MODULE);
210
211	return PTR_ERR_OR_ZERO(rtc);
212}
213
214static const struct i2c_device_id pcf85063_id[] = {
215	{ "pcf85063", 0 },
216	{ }
217};
218MODULE_DEVICE_TABLE(i2c, pcf85063_id);
219
220#ifdef CONFIG_OF
221static const struct of_device_id pcf85063_of_match[] = {
222	{ .compatible = "nxp,pcf85063" },
223	{}
224};
225MODULE_DEVICE_TABLE(of, pcf85063_of_match);
226#endif
227
228static struct i2c_driver pcf85063_driver = {
229	.driver		= {
230		.name	= "rtc-pcf85063",
231		.of_match_table = of_match_ptr(pcf85063_of_match),
232	},
233	.probe		= pcf85063_probe,
234	.id_table	= pcf85063_id,
235};
236
237module_i2c_driver(pcf85063_driver);
238
239MODULE_AUTHOR("Søren Andersen <san@rosetechnology.dk>");
240MODULE_DESCRIPTION("PCF85063 RTC driver");
241MODULE_LICENSE("GPL");