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
  30 struct 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
  40 static struct i2c_driver bq32k_driver;
  41
  42 static 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
  65 static 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
  79 static 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
 100 static 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
 120 static const struct rtc_class_ops bq32k_rtc_ops = {
 121         .read_time      = bq32k_rtc_read_time,
 122         .set_time       = bq32k_rtc_set_time,
 123 };
 124
 125 static 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 = devm_rtc_device_register(&client->dev, bq32k_driver.driver.name,
 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
 166 static const struct i2c_device_id bq32k_id[] = {
 167         { "bq32000", 0 },
 168         { }
 169 };
 170 MODULE_DEVICE_TABLE(i2c, bq32k_id);
 171
 172 static struct i2c_driver bq32k_driver = {
 173         .driver = {
 174                 .name   = "bq32k",
 175                 .owner  = THIS_MODULE,
 176         },
 177         .probe          = bq32k_probe,
 178         .id_table       = bq32k_id,
 179 };
 180
 181 module_i2c_driver(bq32k_driver);
 182
 183 MODULE_AUTHOR("Semihalf, Piotr Ziecik <kosmo@semihalf.com>");
 184 MODULE_DESCRIPTION("TI BQ32000 I2C RTC driver");
 185 MODULE_LICENSE("GPL");