Root/drivers/rtc/rtc-bq32k.c

1/*
2 * Driver for TI BQ32000 RTC.
3 *
4 * Copyright (C) 2009 Semihalf.
5 *
6 * This program is free software; you can redistribute it and/or modify
7 * it under the terms of the GNU General Public License version 2 as
8 * published by the Free Software Foundation.
9 */
10
11#include <linux/module.h>
12#include <linux/i2c.h>
13#include <linux/rtc.h>
14#include <linux/init.h>
15#include <linux/errno.h>
16#include <linux/bcd.h>
17
18#define BQ32K_SECONDS 0x00 /* Seconds register address */
19#define BQ32K_SECONDS_MASK 0x7F /* Mask over seconds value */
20#define BQ32K_STOP 0x80 /* Oscillator Stop flat */
21
22#define BQ32K_MINUTES 0x01 /* Minutes register address */
23#define BQ32K_MINUTES_MASK 0x7F /* Mask over minutes value */
24#define BQ32K_OF 0x80 /* Oscillator Failure flag */
25
26#define BQ32K_HOURS_MASK 0x3F /* Mask over hours value */
27#define BQ32K_CENT 0x40 /* Century flag */
28#define BQ32K_CENT_EN 0x80 /* Century flag enable bit */
29
30struct bq32k_regs {
31    uint8_t seconds;
32    uint8_t minutes;
33    uint8_t cent_hours;
34    uint8_t day;
35    uint8_t date;
36    uint8_t month;
37    uint8_t years;
38};
39
40static struct i2c_driver bq32k_driver;
41
42static int bq32k_read(struct device *dev, void *data, uint8_t off, uint8_t len)
43{
44    struct i2c_client *client = to_i2c_client(dev);
45    struct i2c_msg msgs[] = {
46        {
47            .addr = client->addr,
48            .flags = 0,
49            .len = 1,
50            .buf = &off,
51        }, {
52            .addr = client->addr,
53            .flags = I2C_M_RD,
54            .len = len,
55            .buf = data,
56        }
57    };
58
59    if (i2c_transfer(client->adapter, msgs, 2) == 2)
60        return 0;
61
62    return -EIO;
63}
64
65static int bq32k_write(struct device *dev, void *data, uint8_t off, uint8_t len)
66{
67    struct i2c_client *client = to_i2c_client(dev);
68    uint8_t buffer[len + 1];
69
70    buffer[0] = off;
71    memcpy(&buffer[1], data, len);
72
73    if (i2c_master_send(client, buffer, len + 1) == len + 1)
74        return 0;
75
76    return -EIO;
77}
78
79static int bq32k_rtc_read_time(struct device *dev, struct rtc_time *tm)
80{
81    struct bq32k_regs regs;
82    int error;
83
84    error = bq32k_read(dev, &regs, 0, sizeof(regs));
85    if (error)
86        return error;
87
88    tm->tm_sec = bcd2bin(regs.seconds & BQ32K_SECONDS_MASK);
89    tm->tm_min = bcd2bin(regs.minutes & BQ32K_SECONDS_MASK);
90    tm->tm_hour = bcd2bin(regs.cent_hours & BQ32K_HOURS_MASK);
91    tm->tm_mday = bcd2bin(regs.date);
92    tm->tm_wday = bcd2bin(regs.day) - 1;
93    tm->tm_mon = bcd2bin(regs.month) - 1;
94    tm->tm_year = bcd2bin(regs.years) +
95                ((regs.cent_hours & BQ32K_CENT) ? 100 : 0);
96
97    return rtc_valid_tm(tm);
98}
99
100static int bq32k_rtc_set_time(struct device *dev, struct rtc_time *tm)
101{
102    struct bq32k_regs regs;
103
104    regs.seconds = bin2bcd(tm->tm_sec);
105    regs.minutes = bin2bcd(tm->tm_min);
106    regs.cent_hours = bin2bcd(tm->tm_hour) | BQ32K_CENT_EN;
107    regs.day = bin2bcd(tm->tm_wday + 1);
108    regs.date = bin2bcd(tm->tm_mday);
109    regs.month = bin2bcd(tm->tm_mon + 1);
110
111    if (tm->tm_year >= 100) {
112        regs.cent_hours |= BQ32K_CENT;
113        regs.years = bin2bcd(tm->tm_year - 100);
114    } else
115        regs.years = bin2bcd(tm->tm_year);
116
117    return bq32k_write(dev, &regs, 0, sizeof(regs));
118}
119
120static const struct rtc_class_ops bq32k_rtc_ops = {
121    .read_time = bq32k_rtc_read_time,
122    .set_time = bq32k_rtc_set_time,
123};
124
125static int bq32k_probe(struct i2c_client *client,
126                const struct i2c_device_id *id)
127{
128    struct device *dev = &client->dev;
129    struct rtc_device *rtc;
130    uint8_t reg;
131    int error;
132
133    if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C))
134        return -ENODEV;
135
136    /* Check Oscillator Stop flag */
137    error = bq32k_read(dev, &reg, BQ32K_SECONDS, 1);
138    if (!error && (reg & BQ32K_STOP)) {
139        dev_warn(dev, "Oscillator was halted. Restarting...\n");
140        reg &= ~BQ32K_STOP;
141        error = bq32k_write(dev, &reg, BQ32K_SECONDS, 1);
142    }
143    if (error)
144        return error;
145
146    /* Check Oscillator Failure flag */
147    error = bq32k_read(dev, &reg, BQ32K_MINUTES, 1);
148    if (!error && (reg & BQ32K_OF)) {
149        dev_warn(dev, "Oscillator Failure. Check RTC battery.\n");
150        reg &= ~BQ32K_OF;
151        error = bq32k_write(dev, &reg, BQ32K_MINUTES, 1);
152    }
153    if (error)
154        return error;
155
156    rtc = rtc_device_register(bq32k_driver.driver.name, &client->dev,
157                        &bq32k_rtc_ops, THIS_MODULE);
158    if (IS_ERR(rtc))
159        return PTR_ERR(rtc);
160
161    i2c_set_clientdata(client, rtc);
162
163    return 0;
164}
165
166static int __devexit bq32k_remove(struct i2c_client *client)
167{
168    struct rtc_device *rtc = i2c_get_clientdata(client);
169
170    rtc_device_unregister(rtc);
171    return 0;
172}
173
174static const struct i2c_device_id bq32k_id[] = {
175    { "bq32000", 0 },
176    { }
177};
178MODULE_DEVICE_TABLE(i2c, bq32k_id);
179
180static struct i2c_driver bq32k_driver = {
181    .driver = {
182        .name = "bq32k",
183        .owner = THIS_MODULE,
184    },
185    .probe = bq32k_probe,
186    .remove = __devexit_p(bq32k_remove),
187    .id_table = bq32k_id,
188};
189
190module_i2c_driver(bq32k_driver);
191
192MODULE_AUTHOR("Semihalf, Piotr Ziecik <kosmo@semihalf.com>");
193MODULE_DESCRIPTION("TI BQ32000 I2C RTC driver");
194MODULE_LICENSE("GPL");
195

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