drivers/rtc/rtc-s35390a.c

   1 /*
   2  * Seiko Instruments S-35390A RTC Driver
   3  *
   4  * Copyright (c) 2007 Byron Bradley
   5  *
   6  * This program is free software; you can redistribute it and/or
   7  * modify it under the terms of the GNU General Public License
   8  * as published by the Free Software Foundation; either version
   9  * 2 of the License, or (at your option) any later version.
  10  */
  11
  12 #include <linux/module.h>
  13 #include <linux/rtc.h>
  14 #include <linux/i2c.h>
  15 #include <linux/bitrev.h>
  16 #include <linux/bcd.h>
  17 #include <linux/slab.h>
  18
  19 #define S35390A_CMD_STATUS1     0
  20 #define S35390A_CMD_STATUS2     1
  21 #define S35390A_CMD_TIME1       2
  22
  23 #define S35390A_BYTE_YEAR       0
  24 #define S35390A_BYTE_MONTH      1
  25 #define S35390A_BYTE_DAY        2
  26 #define S35390A_BYTE_WDAY       3
  27 #define S35390A_BYTE_HOURS      4
  28 #define S35390A_BYTE_MINS       5
  29 #define S35390A_BYTE_SECS       6
  30
  31 #define S35390A_FLAG_POC        0x01
  32 #define S35390A_FLAG_BLD        0x02
  33 #define S35390A_FLAG_24H        0x40
  34 #define S35390A_FLAG_RESET      0x80
  35 #define S35390A_FLAG_TEST       0x01
  36
  37 static const struct i2c_device_id s35390a_id[] = {
  38         { "s35390a", 0 },
  39         { }
  40 };
  41 MODULE_DEVICE_TABLE(i2c, s35390a_id);
  42
  43 struct s35390a {
  44         struct i2c_client *client[8];
  45         struct rtc_device *rtc;
  46         int twentyfourhour;
  47 };
  48
  49 static int s35390a_set_reg(struct s35390a *s35390a, int reg, char *buf, int len)
  50 {
  51         struct i2c_client *client = s35390a->client[reg];
  52         struct i2c_msg msg[] = {
  53                 { client->addr, 0, len, buf },
  54         };
  55
  56         if ((i2c_transfer(client->adapter, msg, 1)) != 1)
  57                 return -EIO;
  58
  59         return 0;
  60 }
  61
  62 static int s35390a_get_reg(struct s35390a *s35390a, int reg, char *buf, int len)
  63 {
  64         struct i2c_client *client = s35390a->client[reg];
  65         struct i2c_msg msg[] = {
  66                 { client->addr, I2C_M_RD, len, buf },
  67         };
  68
  69         if ((i2c_transfer(client->adapter, msg, 1)) != 1)
  70                 return -EIO;
  71
  72         return 0;
  73 }
  74
  75 static int s35390a_reset(struct s35390a *s35390a)
  76 {
  77         char buf[1];
  78
  79         if (s35390a_get_reg(s35390a, S35390A_CMD_STATUS1, buf, sizeof(buf)) < 0)
  80                 return -EIO;
  81
  82         if (!(buf[0] & (S35390A_FLAG_POC | S35390A_FLAG_BLD)))
  83                 return 0;
  84
  85         buf[0] |= (S35390A_FLAG_RESET | S35390A_FLAG_24H);
  86         buf[0] &= 0xf0;
  87         return s35390a_set_reg(s35390a, S35390A_CMD_STATUS1, buf, sizeof(buf));
  88 }
  89
  90 static int s35390a_disable_test_mode(struct s35390a *s35390a)
  91 {
  92         char buf[1];
  93
  94         if (s35390a_get_reg(s35390a, S35390A_CMD_STATUS2, buf, sizeof(buf)) < 0)
  95                 return -EIO;
  96
  97         if (!(buf[0] & S35390A_FLAG_TEST))
  98                 return 0;
  99
 100         buf[0] &= ~S35390A_FLAG_TEST;
 101         return s35390a_set_reg(s35390a, S35390A_CMD_STATUS2, buf, sizeof(buf));
 102 }
 103
 104 static char s35390a_hr2reg(struct s35390a *s35390a, int hour)
 105 {
 106         if (s35390a->twentyfourhour)
 107                 return bin2bcd(hour);
 108
 109         if (hour < 12)
 110                 return bin2bcd(hour);
 111
 112         return 0x40 | bin2bcd(hour - 12);
 113 }
 114
 115 static int s35390a_reg2hr(struct s35390a *s35390a, char reg)
 116 {
 117         unsigned hour;
 118
 119         if (s35390a->twentyfourhour)
 120                 return bcd2bin(reg & 0x3f);
 121
 122         hour = bcd2bin(reg & 0x3f);
 123         if (reg & 0x40)
 124                 hour += 12;
 125
 126         return hour;
 127 }
 128
 129 static int s35390a_set_datetime(struct i2c_client *client, struct rtc_time *tm)
 130 {
 131         struct s35390a  *s35390a = i2c_get_clientdata(client);
 132         int i, err;
 133         char buf[7];
 134
 135         dev_dbg(&client->dev, "%s: tm is secs=%d, mins=%d, hours=%d mday=%d, "
 136                 "mon=%d, year=%d, wday=%d\n", __func__, tm->tm_sec,
 137                 tm->tm_min, tm->tm_hour, tm->tm_mday, tm->tm_mon, tm->tm_year,
 138                 tm->tm_wday);
 139
 140         buf[S35390A_BYTE_YEAR] = bin2bcd(tm->tm_year - 100);
 141         buf[S35390A_BYTE_MONTH] = bin2bcd(tm->tm_mon + 1);
 142         buf[S35390A_BYTE_DAY] = bin2bcd(tm->tm_mday);
 143         buf[S35390A_BYTE_WDAY] = bin2bcd(tm->tm_wday);
 144         buf[S35390A_BYTE_HOURS] = s35390a_hr2reg(s35390a, tm->tm_hour);
 145         buf[S35390A_BYTE_MINS] = bin2bcd(tm->tm_min);
 146         buf[S35390A_BYTE_SECS] = bin2bcd(tm->tm_sec);
 147
 148         /* This chip expects the bits of each byte to be in reverse order */
 149         for (i = 0; i < 7; ++i)
 150                 buf[i] = bitrev8(buf[i]);
 151
 152         err = s35390a_set_reg(s35390a, S35390A_CMD_TIME1, buf, sizeof(buf));
 153
 154         return err;
 155 }
 156
 157 static int s35390a_get_datetime(struct i2c_client *client, struct rtc_time *tm)
 158 {
 159         struct s35390a *s35390a = i2c_get_clientdata(client);
 160         char buf[7];
 161         int i, err;
 162
 163         err = s35390a_get_reg(s35390a, S35390A_CMD_TIME1, buf, sizeof(buf));
 164         if (err < 0)
 165                 return err;
 166
 167         /* This chip returns the bits of each byte in reverse order */
 168         for (i = 0; i < 7; ++i)
 169                 buf[i] = bitrev8(buf[i]);
 170
 171         tm->tm_sec = bcd2bin(buf[S35390A_BYTE_SECS]);
 172         tm->tm_min = bcd2bin(buf[S35390A_BYTE_MINS]);
 173         tm->tm_hour = s35390a_reg2hr(s35390a, buf[S35390A_BYTE_HOURS]);
 174         tm->tm_wday = bcd2bin(buf[S35390A_BYTE_WDAY]);
 175         tm->tm_mday = bcd2bin(buf[S35390A_BYTE_DAY]);
 176         tm->tm_mon = bcd2bin(buf[S35390A_BYTE_MONTH]) - 1;
 177         tm->tm_year = bcd2bin(buf[S35390A_BYTE_YEAR]) + 100;
 178
 179         dev_dbg(&client->dev, "%s: tm is secs=%d, mins=%d, hours=%d, mday=%d, "
 180                 "mon=%d, year=%d, wday=%d\n", __func__, tm->tm_sec,
 181                 tm->tm_min, tm->tm_hour, tm->tm_mday, tm->tm_mon, tm->tm_year,
 182                 tm->tm_wday);
 183
 184         return rtc_valid_tm(tm);
 185 }
 186
 187 static int s35390a_rtc_read_time(struct device *dev, struct rtc_time *tm)
 188 {
 189         return s35390a_get_datetime(to_i2c_client(dev), tm);
 190 }
 191
 192 static int s35390a_rtc_set_time(struct device *dev, struct rtc_time *tm)
 193 {
 194         return s35390a_set_datetime(to_i2c_client(dev), tm);
 195 }
 196
 197 static const struct rtc_class_ops s35390a_rtc_ops = {
 198         .read_time      = s35390a_rtc_read_time,
 199         .set_time       = s35390a_rtc_set_time,
 200 };
 201
 202 static struct i2c_driver s35390a_driver;
 203
 204 static int s35390a_probe(struct i2c_client *client,
 205                          const struct i2c_device_id *id)
 206 {
 207         int err;
 208         unsigned int i;
 209         struct s35390a *s35390a;
 210         struct rtc_time tm;
 211         char buf[1];
 212
 213         if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C)) {
 214                 err = -ENODEV;
 215                 goto exit;
 216         }
 217
 218         s35390a = kzalloc(sizeof(struct s35390a), GFP_KERNEL);
 219         if (!s35390a) {
 220                 err = -ENOMEM;
 221                 goto exit;
 222         }
 223
 224         s35390a->client[0] = client;
 225         i2c_set_clientdata(client, s35390a);
 226
 227         /* This chip uses multiple addresses, use dummy devices for them */
 228         for (i = 1; i < 8; ++i) {
 229                 s35390a->client[i] = i2c_new_dummy(client->adapter,
 230                                         client->addr + i);
 231                 if (!s35390a->client[i]) {
 232                         dev_err(&client->dev, "Address %02x unavailable\n",
 233                                                 client->addr + i);
 234                         err = -EBUSY;
 235                         goto exit_dummy;
 236                 }
 237         }
 238
 239         err = s35390a_reset(s35390a);
 240         if (err < 0) {
 241                 dev_err(&client->dev, "error resetting chip\n");
 242                 goto exit_dummy;
 243         }
 244
 245         err = s35390a_disable_test_mode(s35390a);
 246         if (err < 0) {
 247                 dev_err(&client->dev, "error disabling test mode\n");
 248                 goto exit_dummy;
 249         }
 250
 251         err = s35390a_get_reg(s35390a, S35390A_CMD_STATUS1, buf, sizeof(buf));
 252         if (err < 0) {
 253                 dev_err(&client->dev, "error checking 12/24 hour mode\n");
 254                 goto exit_dummy;
 255         }
 256         if (buf[0] & S35390A_FLAG_24H)
 257                 s35390a->twentyfourhour = 1;
 258         else
 259                 s35390a->twentyfourhour = 0;
 260
 261         if (s35390a_get_datetime(client, &tm) < 0)
 262                 dev_warn(&client->dev, "clock needs to be set\n");
 263
 264         s35390a->rtc = rtc_device_register(s35390a_driver.driver.name,
 265                                 &client->dev, &s35390a_rtc_ops, THIS_MODULE);
 266
 267         if (IS_ERR(s35390a->rtc)) {
 268                 err = PTR_ERR(s35390a->rtc);
 269                 goto exit_dummy;
 270         }
 271         return 0;
 272
 273 exit_dummy:
 274         for (i = 1; i < 8; ++i)
 275                 if (s35390a->client[i])
 276                         i2c_unregister_device(s35390a->client[i]);
 277         kfree(s35390a);
 278
 279 exit:
 280         return err;
 281 }
 282
 283 static int s35390a_remove(struct i2c_client *client)
 284 {
 285         unsigned int i;
 286
 287         struct s35390a *s35390a = i2c_get_clientdata(client);
 288         for (i = 1; i < 8; ++i)
 289                 if (s35390a->client[i])
 290                         i2c_unregister_device(s35390a->client[i]);
 291
 292         rtc_device_unregister(s35390a->rtc);
 293         kfree(s35390a);
 294
 295         return 0;
 296 }
 297
 298 static struct i2c_driver s35390a_driver = {
 299         .driver         = {
 300                 .name   = "rtc-s35390a",
 301         },
 302         .probe          = s35390a_probe,
 303         .remove         = s35390a_remove,
 304         .id_table       = s35390a_id,
 305 };
 306
 307 module_i2c_driver(s35390a_driver);
 308
 309 MODULE_AUTHOR("Byron Bradley <byron.bbradley@gmail.com>");
 310 MODULE_DESCRIPTION("S35390A RTC driver");
 311 MODULE_LICENSE("GPL");