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/drivers/rtc/rtc-ds1672.c

https://bitbucket.org/cyanogenmod/android_kernel_asus_tf300t
C | 220 lines | 149 code | 50 blank | 21 comment | 13 complexity | 8a9209ccb23a08c136ae7a66160eb26e MD5 | raw file
Possible License(s): LGPL-2.0, AGPL-1.0, GPL-2.0
  1/*
  2 * An rtc/i2c driver for the Dallas DS1672
  3 * Copyright 2005-06 Tower Technologies
  4 *
  5 * Author: Alessandro Zummo <a.zummo@towertech.it>
  6 *
  7 * This program is free software; you can redistribute it and/or modify
  8 * it under the terms of the GNU General Public License version 2 as
  9 * published by the Free Software Foundation.
 10 */
 11
 12#include <linux/i2c.h>
 13#include <linux/rtc.h>
 14
 15#define DRV_VERSION "0.4"
 16
 17/* Registers */
 18
 19#define DS1672_REG_CNT_BASE	0
 20#define DS1672_REG_CONTROL	4
 21#define DS1672_REG_TRICKLE	5
 22
 23#define DS1672_REG_CONTROL_EOSC	0x80
 24
 25static struct i2c_driver ds1672_driver;
 26
 27/*
 28 * In the routines that deal directly with the ds1672 hardware, we use
 29 * rtc_time -- month 0-11, hour 0-23, yr = calendar year-epoch
 30 * Epoch is initialized as 2000. Time is set to UTC.
 31 */
 32static int ds1672_get_datetime(struct i2c_client *client, struct rtc_time *tm)
 33{
 34	unsigned long time;
 35	unsigned char addr = DS1672_REG_CNT_BASE;
 36	unsigned char buf[4];
 37
 38	struct i2c_msg msgs[] = {
 39		{client->addr, 0, 1, &addr},	/* setup read ptr */
 40		{client->addr, I2C_M_RD, 4, buf},	/* read date */
 41	};
 42
 43	/* read date registers */
 44	if ((i2c_transfer(client->adapter, &msgs[0], 2)) != 2) {
 45		dev_err(&client->dev, "%s: read error\n", __func__);
 46		return -EIO;
 47	}
 48
 49	dev_dbg(&client->dev,
 50		"%s: raw read data - counters=%02x,%02x,%02x,%02x\n",
 51		__func__, buf[0], buf[1], buf[2], buf[3]);
 52
 53	time = (buf[3] << 24) | (buf[2] << 16) | (buf[1] << 8) | buf[0];
 54
 55	rtc_time_to_tm(time, tm);
 56
 57	dev_dbg(&client->dev, "%s: tm is secs=%d, mins=%d, hours=%d, "
 58		"mday=%d, mon=%d, year=%d, wday=%d\n",
 59		__func__, tm->tm_sec, tm->tm_min, tm->tm_hour,
 60		tm->tm_mday, tm->tm_mon, tm->tm_year, tm->tm_wday);
 61
 62	return 0;
 63}
 64
 65static int ds1672_set_mmss(struct i2c_client *client, unsigned long secs)
 66{
 67	int xfer;
 68	unsigned char buf[6];
 69
 70	buf[0] = DS1672_REG_CNT_BASE;
 71	buf[1] = secs & 0x000000FF;
 72	buf[2] = (secs & 0x0000FF00) >> 8;
 73	buf[3] = (secs & 0x00FF0000) >> 16;
 74	buf[4] = (secs & 0xFF000000) >> 24;
 75	buf[5] = 0;		/* set control reg to enable counting */
 76
 77	xfer = i2c_master_send(client, buf, 6);
 78	if (xfer != 6) {
 79		dev_err(&client->dev, "%s: send: %d\n", __func__, xfer);
 80		return -EIO;
 81	}
 82
 83	return 0;
 84}
 85
 86static int ds1672_rtc_read_time(struct device *dev, struct rtc_time *tm)
 87{
 88	return ds1672_get_datetime(to_i2c_client(dev), tm);
 89}
 90
 91static int ds1672_rtc_set_mmss(struct device *dev, unsigned long secs)
 92{
 93	return ds1672_set_mmss(to_i2c_client(dev), secs);
 94}
 95
 96static int ds1672_get_control(struct i2c_client *client, u8 *status)
 97{
 98	unsigned char addr = DS1672_REG_CONTROL;
 99
100	struct i2c_msg msgs[] = {
101		{client->addr, 0, 1, &addr},	/* setup read ptr */
102		{client->addr, I2C_M_RD, 1, status},	/* read control */
103	};
104
105	/* read control register */
106	if ((i2c_transfer(client->adapter, &msgs[0], 2)) != 2) {
107		dev_err(&client->dev, "%s: read error\n", __func__);
108		return -EIO;
109	}
110
111	return 0;
112}
113
114/* following are the sysfs callback functions */
115static ssize_t show_control(struct device *dev, struct device_attribute *attr,
116			    char *buf)
117{
118	struct i2c_client *client = to_i2c_client(dev);
119	u8 control;
120	int err;
121
122	err = ds1672_get_control(client, &control);
123	if (err)
124		return err;
125
126	return sprintf(buf, "%s\n", (control & DS1672_REG_CONTROL_EOSC)
127		       ? "disabled" : "enabled");
128}
129
130static DEVICE_ATTR(control, S_IRUGO, show_control, NULL);
131
132static const struct rtc_class_ops ds1672_rtc_ops = {
133	.read_time = ds1672_rtc_read_time,
134	.set_mmss = ds1672_rtc_set_mmss,
135};
136
137static int ds1672_remove(struct i2c_client *client)
138{
139	struct rtc_device *rtc = i2c_get_clientdata(client);
140
141	if (rtc)
142		rtc_device_unregister(rtc);
143
144	return 0;
145}
146
147static int ds1672_probe(struct i2c_client *client,
148			const struct i2c_device_id *id)
149{
150	int err = 0;
151	u8 control;
152	struct rtc_device *rtc;
153
154	dev_dbg(&client->dev, "%s\n", __func__);
155
156	if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C))
157		return -ENODEV;
158
159	dev_info(&client->dev, "chip found, driver version " DRV_VERSION "\n");
160
161	rtc = rtc_device_register(ds1672_driver.driver.name, &client->dev,
162				  &ds1672_rtc_ops, THIS_MODULE);
163
164	if (IS_ERR(rtc))
165		return PTR_ERR(rtc);
166
167	i2c_set_clientdata(client, rtc);
168
169	/* read control register */
170	err = ds1672_get_control(client, &control);
171	if (err)
172		goto exit_devreg;
173
174	if (control & DS1672_REG_CONTROL_EOSC)
175		dev_warn(&client->dev, "Oscillator not enabled. "
176			 "Set time to enable.\n");
177
178	/* Register sysfs hooks */
179	err = device_create_file(&client->dev, &dev_attr_control);
180	if (err)
181		goto exit_devreg;
182
183	return 0;
184
185 exit_devreg:
186	rtc_device_unregister(rtc);
187	return err;
188}
189
190static struct i2c_device_id ds1672_id[] = {
191	{ "ds1672", 0 },
192	{ }
193};
194
195static struct i2c_driver ds1672_driver = {
196	.driver = {
197		   .name = "rtc-ds1672",
198		   },
199	.probe = &ds1672_probe,
200	.remove = &ds1672_remove,
201	.id_table = ds1672_id,
202};
203
204static int __init ds1672_init(void)
205{
206	return i2c_add_driver(&ds1672_driver);
207}
208
209static void __exit ds1672_exit(void)
210{
211	i2c_del_driver(&ds1672_driver);
212}
213
214MODULE_AUTHOR("Alessandro Zummo <a.zummo@towertech.it>");
215MODULE_DESCRIPTION("Dallas/Maxim DS1672 timekeeper driver");
216MODULE_LICENSE("GPL");
217MODULE_VERSION(DRV_VERSION);
218
219module_init(ds1672_init);
220module_exit(ds1672_exit);