1/*
  2 * An I2C driver for the NXP PCF2127 RTC
  3 * Copyright 2013 Til-Technologies
  4 *
  5 * Author: Renaud Cerrato <r.cerrato@til-technologies.fr>
  6 *
  7 * based on the other drivers in this same directory.
  8 *
  9 * http://www.nxp.com/documents/data_sheet/PCF2127AT.pdf
 10 *
 11 * This program is free software; you can redistribute it and/or modify
 12 * it under the terms of the GNU General Public License version 2 as
 13 * published by the Free Software Foundation.
 14 */
 15
 16#include <linux/i2c.h>
 17#include <linux/bcd.h>
 18#include <linux/rtc.h>
 19#include <linux/slab.h>
 20#include <linux/module.h>
 21#include <linux/of.h>
 22
 23#define DRV_VERSION "0.0.1"
 24
 25#define PCF2127_REG_CTRL1       (0x00)  /* Control Register 1 */
 26#define PCF2127_REG_CTRL2       (0x01)  /* Control Register 2 */
 27#define PCF2127_REG_CTRL3       (0x02)  /* Control Register 3 */
 28#define PCF2127_REG_SC          (0x03)  /* datetime */
 29#define PCF2127_REG_MN          (0x04)
 30#define PCF2127_REG_HR          (0x05)
 31#define PCF2127_REG_DM          (0x06)
 32#define PCF2127_REG_DW          (0x07)
 33#define PCF2127_REG_MO          (0x08)
 34#define PCF2127_REG_YR          (0x09)
 35
 36static struct i2c_driver pcf2127_driver;
 37
 38struct pcf2127 {
 39	struct rtc_device *rtc;
 40	int voltage_low; /* indicates if a low_voltage was detected */
 41};
 42
 43/*
 44 * In the routines that deal directly with the pcf2127 hardware, we use
 45 * rtc_time -- month 0-11, hour 0-23, yr = calendar year-epoch.
 46 */
 47static int pcf2127_get_datetime(struct i2c_client *client, struct rtc_time *tm)
 48{
 49	struct pcf2127 *pcf2127 = i2c_get_clientdata(client);
 50	unsigned char buf[10] = { PCF2127_REG_CTRL1 };
 51
 52	/* read registers */
 53	if (i2c_master_send(client, buf, 1) != 1 ||
 54		i2c_master_recv(client, buf, sizeof(buf)) != sizeof(buf)) {
 55		dev_err(&client->dev, "%s: read error\n", __func__);
 56		return -EIO;
 57	}
 58
 59	if (buf[PCF2127_REG_CTRL3] & 0x04) {
 60		pcf2127->voltage_low = 1;
 61		dev_info(&client->dev,
 62			"low voltage detected, date/time is not reliable.\n");
 63	}
 64
 65	dev_dbg(&client->dev,
 66		"%s: raw data is cr1=%02x, cr2=%02x, cr3=%02x, "
 67		"sec=%02x, min=%02x, hr=%02x, "
 68		"mday=%02x, wday=%02x, mon=%02x, year=%02x\n",
 69		__func__,
 70		buf[0], buf[1], buf[2],
 71		buf[3], buf[4], buf[5],
 72		buf[6], buf[7], buf[8], buf[9]);
 73
 74
 75	tm->tm_sec = bcd2bin(buf[PCF2127_REG_SC] & 0x7F);
 76	tm->tm_min = bcd2bin(buf[PCF2127_REG_MN] & 0x7F);
 77	tm->tm_hour = bcd2bin(buf[PCF2127_REG_HR] & 0x3F); /* rtc hr 0-23 */
 78	tm->tm_mday = bcd2bin(buf[PCF2127_REG_DM] & 0x3F);
 79	tm->tm_wday = buf[PCF2127_REG_DW] & 0x07;
 80	tm->tm_mon = bcd2bin(buf[PCF2127_REG_MO] & 0x1F) - 1; /* rtc mn 1-12 */
 81	tm->tm_year = bcd2bin(buf[PCF2127_REG_YR]);
 82	if (tm->tm_year < 70)
 83		tm->tm_year += 100;	/* assume we are in 1970...2069 */
 84
 85	dev_dbg(&client->dev, "%s: tm is secs=%d, mins=%d, hours=%d, "
 86		"mday=%d, mon=%d, year=%d, wday=%d\n",
 87		__func__,
 88		tm->tm_sec, tm->tm_min, tm->tm_hour,
 89		tm->tm_mday, tm->tm_mon, tm->tm_year, tm->tm_wday);
 90
 91	/* the clock can give out invalid datetime, but we cannot return
 92	 * -EINVAL otherwise hwclock will refuse to set the time on bootup.
 93	 */
 94	if (rtc_valid_tm(tm) < 0)
 95		dev_err(&client->dev, "retrieved date/time is not valid.\n");
 96
 97	return 0;
 98}
 99
100static int pcf2127_set_datetime(struct i2c_client *client, struct rtc_time *tm)
101{
102	unsigned char buf[8];
103	int i = 0, err;
104
105	dev_dbg(&client->dev, "%s: secs=%d, mins=%d, hours=%d, "
106		"mday=%d, mon=%d, year=%d, wday=%d\n",
107		__func__,
108		tm->tm_sec, tm->tm_min, tm->tm_hour,
109		tm->tm_mday, tm->tm_mon, tm->tm_year, tm->tm_wday);
110
111	/* start register address */
112	buf[i++] = PCF2127_REG_SC;
113
114	/* hours, minutes and seconds */
115	buf[i++] = bin2bcd(tm->tm_sec);
116	buf[i++] = bin2bcd(tm->tm_min);
117	buf[i++] = bin2bcd(tm->tm_hour);
118	buf[i++] = bin2bcd(tm->tm_mday);
119	buf[i++] = tm->tm_wday & 0x07;
120
121	/* month, 1 - 12 */
122	buf[i++] = bin2bcd(tm->tm_mon + 1);
123
124	/* year */
125	buf[i++] = bin2bcd(tm->tm_year % 100);
126
127	/* write register's data */
128	err = i2c_master_send(client, buf, i);
129	if (err != i) {
130		dev_err(&client->dev,
131			"%s: err=%d", __func__, err);
132		return -EIO;
133	}
134
135	return 0;
136}
137
138#ifdef CONFIG_RTC_INTF_DEV
139static int pcf2127_rtc_ioctl(struct device *dev,
140				unsigned int cmd, unsigned long arg)
141{
142	struct pcf2127 *pcf2127 = i2c_get_clientdata(to_i2c_client(dev));
143
144	switch (cmd) {
145	case RTC_VL_READ:
146		if (pcf2127->voltage_low)
147			dev_info(dev, "low voltage detected, date/time is not reliable.\n");
148
149		if (copy_to_user((void __user *)arg, &pcf2127->voltage_low,
150					sizeof(int)))
151			return -EFAULT;
152		return 0;
153	default:
154		return -ENOIOCTLCMD;
155	}
156}
157#else
158#define pcf2127_rtc_ioctl NULL
159#endif
160
161static int pcf2127_rtc_read_time(struct device *dev, struct rtc_time *tm)
162{
163	return pcf2127_get_datetime(to_i2c_client(dev), tm);
164}
165
166static int pcf2127_rtc_set_time(struct device *dev, struct rtc_time *tm)
167{
168	return pcf2127_set_datetime(to_i2c_client(dev), tm);
169}
170
171static const struct rtc_class_ops pcf2127_rtc_ops = {
172	.ioctl		= pcf2127_rtc_ioctl,
173	.read_time	= pcf2127_rtc_read_time,
174	.set_time	= pcf2127_rtc_set_time,
175};
176
177static int pcf2127_probe(struct i2c_client *client,
178				const struct i2c_device_id *id)
179{
180	struct pcf2127 *pcf2127;
181
182	dev_dbg(&client->dev, "%s\n", __func__);
183
184	if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C))
185		return -ENODEV;
186
187	pcf2127 = devm_kzalloc(&client->dev, sizeof(struct pcf2127),
188				GFP_KERNEL);
189	if (!pcf2127)
190		return -ENOMEM;
191
192	dev_info(&client->dev, "chip found, driver version " DRV_VERSION "\n");
193
194	i2c_set_clientdata(client, pcf2127);
195
196	pcf2127->rtc = devm_rtc_device_register(&client->dev,
197				pcf2127_driver.driver.name,
198				&pcf2127_rtc_ops, THIS_MODULE);
199
200	return PTR_ERR_OR_ZERO(pcf2127->rtc);
201}
202
203static const struct i2c_device_id pcf2127_id[] = {
204	{ "pcf2127", 0 },
205	{ }
206};
207MODULE_DEVICE_TABLE(i2c, pcf2127_id);
208
209#ifdef CONFIG_OF
210static const struct of_device_id pcf2127_of_match[] = {
211	{ .compatible = "nxp,pcf2127" },
212	{}
213};
214MODULE_DEVICE_TABLE(of, pcf2127_of_match);
215#endif
216
217static struct i2c_driver pcf2127_driver = {
218	.driver		= {
219		.name	= "rtc-pcf2127",
220		.owner	= THIS_MODULE,
221		.of_match_table = of_match_ptr(pcf2127_of_match),
222	},
223	.probe		= pcf2127_probe,
224	.id_table	= pcf2127_id,
225};
226
227module_i2c_driver(pcf2127_driver);
228
229MODULE_AUTHOR("Renaud Cerrato <r.cerrato@til-technologies.fr>");
230MODULE_DESCRIPTION("NXP PCF2127 RTC driver");
231MODULE_LICENSE("GPL");
232MODULE_VERSION(DRV_VERSION);