linux/drivers/rtc/rtc-bq32k.c
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   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 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         = 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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