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 struct s35390a {
  38         struct i2c_client *client[8];
  39         struct rtc_device *rtc;
  40         int twentyfourhour;
  41 };
  42
  43 static int s35390a_set_reg(struct s35390a *s35390a, int reg, char *buf, int len)
  44 {
  45         struct i2c_client *client = s35390a->client[reg];
  46         struct i2c_msg msg[] = {
  47                 { client->addr, 0, len, buf },
  48         };
  49
  50         if ((i2c_transfer(client->adapter, msg, 1)) != 1)
  51                 return -EIO;
  52
  53         return 0;
  54 }
  55
  56 static int s35390a_get_reg(struct s35390a *s35390a, int reg, char *buf, int len)
  57 {
  58         struct i2c_client *client = s35390a->client[reg];
  59         struct i2c_msg msg[] = {
  60                 { client->addr, I2C_M_RD, len, buf },
  61         };
  62
  63         if ((i2c_transfer(client->adapter, msg, 1)) != 1)
  64                 return -EIO;
  65
  66         return 0;
  67 }
  68
  69 static int s35390a_reset(struct s35390a *s35390a)
  70 {
  71         char buf[1];
  72
  73         if (s35390a_get_reg(s35390a, S35390A_CMD_STATUS1, buf, sizeof(buf)) < 0)
  74                 return -EIO;
  75
  76         if (!(buf[0] & (S35390A_FLAG_POC | S35390A_FLAG_BLD)))
  77                 return 0;
  78
  79         buf[0] |= (S35390A_FLAG_RESET | S35390A_FLAG_24H);
  80         buf[0] &= 0xf0;
  81         return s35390a_set_reg(s35390a, S35390A_CMD_STATUS1, buf, sizeof(buf));
  82 }
  83
  84 static int s35390a_disable_test_mode(struct s35390a *s35390a)
  85 {
  86         char buf[1];
  87
  88         if (s35390a_get_reg(s35390a, S35390A_CMD_STATUS2, buf, sizeof(buf)) < 0)
  89                 return -EIO;
  90
  91         if (!(buf[0] & S35390A_FLAG_TEST))
  92                 return 0;
  93
  94         buf[0] &= ~S35390A_FLAG_TEST;
  95         return s35390a_set_reg(s35390a, S35390A_CMD_STATUS2, buf, sizeof(buf));
  96 }
  97
  98 static char s35390a_hr2reg(struct s35390a *s35390a, int hour)
  99 {
 100         if (s35390a->twentyfourhour)
 101                 return BIN2BCD(hour);
 102
 103         if (hour < 12)
 104                 return BIN2BCD(hour);
 105
 106         return 0x40 | BIN2BCD(hour - 12);
 107 }
 108
 109 static int s35390a_reg2hr(struct s35390a *s35390a, char reg)
 110 {
 111         unsigned hour;
 112
 113         if (s35390a->twentyfourhour)
 114                 return BCD2BIN(reg & 0x3f);
 115
 116         hour = BCD2BIN(reg & 0x3f);
 117         if (reg & 0x40)
 118                 hour += 12;
 119
 120         return hour;
 121 }
 122
 123 static int s35390a_set_datetime(struct i2c_client *client, struct rtc_time *tm)
 124 {
 125         struct s35390a  *s35390a = i2c_get_clientdata(client);
 126         int i, err;
 127         char buf[7];
 128
 129         dev_dbg(&client->dev, "%s: tm is secs=%d, mins=%d, hours=%d mday=%d, "
 130                 "mon=%d, year=%d, wday=%d\n", __func__, tm->tm_sec,
 131                 tm->tm_min, tm->tm_hour, tm->tm_mday, tm->tm_mon, tm->tm_year,
 132                 tm->tm_wday);
 133
 134         buf[S35390A_BYTE_YEAR] = BIN2BCD(tm->tm_year - 100);
 135         buf[S35390A_BYTE_MONTH] = BIN2BCD(tm->tm_mon + 1);
 136         buf[S35390A_BYTE_DAY] = BIN2BCD(tm->tm_mday);
 137         buf[S35390A_BYTE_WDAY] = BIN2BCD(tm->tm_wday);
 138         buf[S35390A_BYTE_HOURS] = s35390a_hr2reg(s35390a, tm->tm_hour);
 139         buf[S35390A_BYTE_MINS] = BIN2BCD(tm->tm_min);
 140         buf[S35390A_BYTE_SECS] = BIN2BCD(tm->tm_sec);
 141
 142         /* This chip expects the bits of each byte to be in reverse order */
 143         for (i = 0; i < 7; ++i)
 144                 buf[i] = bitrev8(buf[i]);
 145
 146         err = s35390a_set_reg(s35390a, S35390A_CMD_TIME1, buf, sizeof(buf));
 147
 148         return err;
 149 }
 150
 151 static int s35390a_get_datetime(struct i2c_client *client, struct rtc_time *tm)
 152 {
 153         struct s35390a *s35390a = i2c_get_clientdata(client);
 154         char buf[7];
 155         int i, err;
 156
 157         err = s35390a_get_reg(s35390a, S35390A_CMD_TIME1, buf, sizeof(buf));
 158         if (err < 0)
 159                 return err;
 160
 161         /* This chip returns the bits of each byte in reverse order */
 162         for (i = 0; i < 7; ++i)
 163                 buf[i] = bitrev8(buf[i]);
 164
 165         tm->tm_sec = BCD2BIN(buf[S35390A_BYTE_SECS]);
 166         tm->tm_min = BCD2BIN(buf[S35390A_BYTE_MINS]);
 167         tm->tm_hour = s35390a_reg2hr(s35390a, buf[S35390A_BYTE_HOURS]);
 168         tm->tm_wday = BCD2BIN(buf[S35390A_BYTE_WDAY]);
 169         tm->tm_mday = BCD2BIN(buf[S35390A_BYTE_DAY]);
 170         tm->tm_mon = BCD2BIN(buf[S35390A_BYTE_MONTH]) - 1;
 171         tm->tm_year = BCD2BIN(buf[S35390A_BYTE_YEAR]) + 100;
 172
 173         dev_dbg(&client->dev, "%s: tm is secs=%d, mins=%d, hours=%d, mday=%d, "
 174                 "mon=%d, year=%d, wday=%d\n", __func__, tm->tm_sec,
 175                 tm->tm_min, tm->tm_hour, tm->tm_mday, tm->tm_mon, tm->tm_year,
 176                 tm->tm_wday);
 177
 178         return rtc_valid_tm(tm);
 179 }
 180
 181 static int s35390a_rtc_read_time(struct device *dev, struct rtc_time *tm)
 182 {
 183         return s35390a_get_datetime(to_i2c_client(dev), tm);
 184 }
 185
 186 static int s35390a_rtc_set_time(struct device *dev, struct rtc_time *tm)
 187 {
 188         return s35390a_set_datetime(to_i2c_client(dev), tm);
 189 }
 190
 191 static const struct rtc_class_ops s35390a_rtc_ops = {
 192         .read_time      = s35390a_rtc_read_time,
 193         .set_time       = s35390a_rtc_set_time,
 194 };
 195
 196 static struct i2c_driver s35390a_driver;
 197
 198 static int s35390a_probe(struct i2c_client *client)
 199 {
 200         int err;
 201         unsigned int i;
 202         struct s35390a *s35390a;
 203         struct rtc_time tm;
 204         char buf[1];
 205
 206         if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C)) {
 207                 err = -ENODEV;
 208                 goto exit;
 209         }
 210
 211         s35390a = kzalloc(sizeof(struct s35390a), GFP_KERNEL);
 212         if (!s35390a) {
 213                 err = -ENOMEM;
 214                 goto exit;
 215         }
 216
 217         s35390a->client[0] = client;
 218         i2c_set_clientdata(client, s35390a);
 219
 220         /* This chip uses multiple addresses, use dummy devices for them */
 221         for (i = 1; i < 8; ++i) {
 222                 s35390a->client[i] = i2c_new_dummy(client->adapter,
 223                                         client->addr + i, "rtc-s35390a");
 224                 if (!s35390a->client[i]) {
 225                         dev_err(&client->dev, "Address %02x unavailable\n",
 226                                                 client->addr + i);
 227                         err = -EBUSY;
 228                         goto exit_dummy;
 229                 }
 230         }
 231
 232         err = s35390a_reset(s35390a);
 233         if (err < 0) {
 234                 dev_err(&client->dev, "error resetting chip\n");
 235                 goto exit_dummy;
 236         }
 237
 238         err = s35390a_disable_test_mode(s35390a);
 239         if (err < 0) {
 240                 dev_err(&client->dev, "error disabling test mode\n");
 241                 goto exit_dummy;
 242         }
 243
 244         err = s35390a_get_reg(s35390a, S35390A_CMD_STATUS1, buf, sizeof(buf));
 245         if (err < 0) {
 246                 dev_err(&client->dev, "error checking 12/24 hour mode\n");
 247                 goto exit_dummy;
 248         }
 249         if (buf[0] & S35390A_FLAG_24H)
 250                 s35390a->twentyfourhour = 1;
 251         else
 252                 s35390a->twentyfourhour = 0;
 253
 254         if (s35390a_get_datetime(client, &tm) < 0)
 255                 dev_warn(&client->dev, "clock needs to be set\n");
 256
 257         s35390a->rtc = rtc_device_register(s35390a_driver.driver.name,
 258                                 &client->dev, &s35390a_rtc_ops, THIS_MODULE);
 259
 260         if (IS_ERR(s35390a->rtc)) {
 261                 err = PTR_ERR(s35390a->rtc);
 262                 goto exit_dummy;
 263         }
 264         return 0;
 265
 266 exit_dummy:
 267         for (i = 1; i < 8; ++i)
 268                 if (s35390a->client[i])
 269                         i2c_unregister_device(s35390a->client[i]);
 270         kfree(s35390a);
 271         i2c_set_clientdata(client, NULL);
 272
 273 exit:
 274         return err;
 275 }
 276
 277 static int s35390a_remove(struct i2c_client *client)
 278 {
 279         unsigned int i;
 280
 281         struct s35390a *s35390a = i2c_get_clientdata(client);
 282         for (i = 1; i < 8; ++i)
 283                 if (s35390a->client[i])
 284                         i2c_unregister_device(s35390a->client[i]);
 285
 286         rtc_device_unregister(s35390a->rtc);
 287         kfree(s35390a);
 288         i2c_set_clientdata(client, NULL);
 289
 290         return 0;
 291 }
 292
 293 static struct i2c_driver s35390a_driver = {
 294         .driver         = {
 295                 .name   = "rtc-s35390a",
 296         },
 297         .probe          = s35390a_probe,
 298         .remove         = s35390a_remove,
 299 };
 300
 301 static int __init s35390a_rtc_init(void)
 302 {
 303         return i2c_add_driver(&s35390a_driver);
 304 }
 305
 306 static void __exit s35390a_rtc_exit(void)
 307 {
 308         i2c_del_driver(&s35390a_driver);
 309 }
 310
 311 MODULE_AUTHOR("Byron Bradley <byron.bbradley@gmail.com>");
 312 MODULE_DESCRIPTION("S35390A RTC driver");
 313 MODULE_LICENSE("GPL");
 314
 315 module_init(s35390a_rtc_init);
 316 module_exit(s35390a_rtc_exit);