drivers/rtc/rtc-pcf8583.c

   1 /*
   2  *  drivers/rtc/rtc-pcf8583.c
   3  *
   4  *  Copyright (C) 2000 Russell King
   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  *  Driver for PCF8583 RTC & RAM chip
  11  *
  12  *  Converted to the generic RTC susbsystem by G. Liakhovetski (2006)
  13  */
  14 #include <linux/module.h>
  15 #include <linux/i2c.h>
  16 #include <linux/slab.h>
  17 #include <linux/string.h>
  18 #include <linux/mc146818rtc.h>
  19 #include <linux/init.h>
  20 #include <linux/errno.h>
  21 #include <linux/bcd.h>
  22
  23 struct rtc_mem {
  24         unsigned int    loc;
  25         unsigned int    nr;
  26         unsigned char   *data;
  27 };
  28
  29 struct pcf8583 {
  30         struct i2c_client client;
  31         struct rtc_device *rtc;
  32         unsigned char ctrl;
  33 };
  34
  35 #define CTRL_STOP       0x80
  36 #define CTRL_HOLD       0x40
  37 #define CTRL_32KHZ      0x00
  38 #define CTRL_MASK       0x08
  39 #define CTRL_ALARMEN    0x04
  40 #define CTRL_ALARM      0x02
  41 #define CTRL_TIMER      0x01
  42
  43 static const unsigned short normal_i2c[] = { 0x50, I2C_CLIENT_END };
  44
  45 /* Module parameters */
  46 I2C_CLIENT_INSMOD;
  47
  48 static struct i2c_driver pcf8583_driver;
  49
  50 #define get_ctrl(x)    ((struct pcf8583 *)i2c_get_clientdata(x))->ctrl
  51 #define set_ctrl(x, v) get_ctrl(x) = v
  52
  53 #define CMOS_YEAR       (64 + 128)
  54 #define CMOS_CHECKSUM   (63)
  55
  56 static int pcf8583_get_datetime(struct i2c_client *client, struct rtc_time *dt)
  57 {
  58         unsigned char buf[8], addr[1] = { 1 };
  59         struct i2c_msg msgs[2] = {
  60                 {
  61                         .addr = client->addr,
  62                         .flags = 0,
  63                         .len = 1,
  64                         .buf = addr,
  65                 }, {
  66                         .addr = client->addr,
  67                         .flags = I2C_M_RD,
  68                         .len = 6,
  69                         .buf = buf,
  70                 }
  71         };
  72         int ret;
  73
  74         memset(buf, 0, sizeof(buf));
  75
  76         ret = i2c_transfer(client->adapter, msgs, 2);
  77         if (ret == 2) {
  78                 dt->tm_year = buf[4] >> 6;
  79                 dt->tm_wday = buf[5] >> 5;
  80
  81                 buf[4] &= 0x3f;
  82                 buf[5] &= 0x1f;
  83
  84                 dt->tm_sec = BCD2BIN(buf[1]);
  85                 dt->tm_min = BCD2BIN(buf[2]);
  86                 dt->tm_hour = BCD2BIN(buf[3]);
  87                 dt->tm_mday = BCD2BIN(buf[4]);
  88                 dt->tm_mon = BCD2BIN(buf[5]) - 1;
  89         }
  90
  91         return ret == 2 ? 0 : -EIO;
  92 }
  93
  94 static int pcf8583_set_datetime(struct i2c_client *client, struct rtc_time *dt, int datetoo)
  95 {
  96         unsigned char buf[8];
  97         int ret, len = 6;
  98
  99         buf[0] = 0;
 100         buf[1] = get_ctrl(client) | 0x80;
 101         buf[2] = 0;
 102         buf[3] = BIN2BCD(dt->tm_sec);
 103         buf[4] = BIN2BCD(dt->tm_min);
 104         buf[5] = BIN2BCD(dt->tm_hour);
 105
 106         if (datetoo) {
 107                 len = 8;
 108                 buf[6] = BIN2BCD(dt->tm_mday) | (dt->tm_year << 6);
 109                 buf[7] = BIN2BCD(dt->tm_mon + 1)  | (dt->tm_wday << 5);
 110         }
 111
 112         ret = i2c_master_send(client, (char *)buf, len);
 113         if (ret != len)
 114                 return -EIO;
 115
 116         buf[1] = get_ctrl(client);
 117         ret = i2c_master_send(client, (char *)buf, 2);
 118
 119         return ret == 2 ? 0 : -EIO;
 120 }
 121
 122 static int pcf8583_get_ctrl(struct i2c_client *client, unsigned char *ctrl)
 123 {
 124         *ctrl = get_ctrl(client);
 125         return 0;
 126 }
 127
 128 static int pcf8583_set_ctrl(struct i2c_client *client, unsigned char *ctrl)
 129 {
 130         unsigned char buf[2];
 131
 132         buf[0] = 0;
 133         buf[1] = *ctrl;
 134         set_ctrl(client, *ctrl);
 135
 136         return i2c_master_send(client, (char *)buf, 2);
 137 }
 138
 139 static int pcf8583_read_mem(struct i2c_client *client, struct rtc_mem *mem)
 140 {
 141         unsigned char addr[1];
 142         struct i2c_msg msgs[2] = {
 143                 {
 144                         .addr = client->addr,
 145                         .flags = 0,
 146                         .len = 1,
 147                         .buf = addr,
 148                 }, {
 149                         .addr = client->addr,
 150                         .flags = I2C_M_RD,
 151                         .len = mem->nr,
 152                         .buf = mem->data,
 153                 }
 154         };
 155
 156         if (mem->loc < 8)
 157                 return -EINVAL;
 158
 159         addr[0] = mem->loc;
 160
 161         return i2c_transfer(client->adapter, msgs, 2) == 2 ? 0 : -EIO;
 162 }
 163
 164 static int pcf8583_write_mem(struct i2c_client *client, struct rtc_mem *mem)
 165 {
 166         unsigned char addr[1];
 167         struct i2c_msg msgs[2] = {
 168                 {
 169                         .addr = client->addr,
 170                         .flags = 0,
 171                         .len = 1,
 172                         .buf = addr,
 173                 }, {
 174                         .addr = client->addr,
 175                         .flags = I2C_M_NOSTART,
 176                         .len = mem->nr,
 177                         .buf = mem->data,
 178                 }
 179         };
 180
 181         if (mem->loc < 8)
 182                 return -EINVAL;
 183
 184         addr[0] = mem->loc;
 185
 186         return i2c_transfer(client->adapter, msgs, 2) == 2 ? 0 : -EIO;
 187 }
 188
 189 static int pcf8583_rtc_read_time(struct device *dev, struct rtc_time *tm)
 190 {
 191         struct i2c_client *client = to_i2c_client(dev);
 192         unsigned char ctrl, year[2];
 193         struct rtc_mem mem = { CMOS_YEAR, sizeof(year), year };
 194         int real_year, year_offset, err;
 195
 196         /*
 197          * Ensure that the RTC is running.
 198          */
 199         pcf8583_get_ctrl(client, &ctrl);
 200         if (ctrl & (CTRL_STOP | CTRL_HOLD)) {
 201                 unsigned char new_ctrl = ctrl & ~(CTRL_STOP | CTRL_HOLD);
 202
 203                 printk(KERN_WARNING "RTC: resetting control %02x -> %02x\n",
 204                        ctrl, new_ctrl);
 205
 206                 if ((err = pcf8583_set_ctrl(client, &new_ctrl)) < 0)
 207                         return err;
 208         }
 209
 210         if (pcf8583_get_datetime(client, tm) ||
 211             pcf8583_read_mem(client, &mem))
 212                 return -EIO;
 213
 214         real_year = year[0];
 215
 216         /*
 217          * The RTC year holds the LSB two bits of the current
 218          * year, which should reflect the LSB two bits of the
 219          * CMOS copy of the year.  Any difference indicates
 220          * that we have to correct the CMOS version.
 221          */
 222         year_offset = tm->tm_year - (real_year & 3);
 223         if (year_offset < 0)
 224                 /*
 225                  * RTC year wrapped.  Adjust it appropriately.
 226                  */
 227                 year_offset += 4;
 228
 229         tm->tm_year = (real_year + year_offset + year[1] * 100) - 1900;
 230
 231         return 0;
 232 }
 233
 234 static int pcf8583_rtc_set_time(struct device *dev, struct rtc_time *tm)
 235 {
 236         struct i2c_client *client = to_i2c_client(dev);
 237         unsigned char year[2], chk;
 238         struct rtc_mem cmos_year  = { CMOS_YEAR, sizeof(year), year };
 239         struct rtc_mem cmos_check = { CMOS_CHECKSUM, 1, &chk };
 240         unsigned int proper_year = tm->tm_year + 1900;
 241         int ret;
 242
 243         /*
 244          * The RTC's own 2-bit year must reflect the least
 245          * significant two bits of the CMOS year.
 246          */
 247
 248         ret = pcf8583_set_datetime(client, tm, 1);
 249         if (ret)
 250                 return ret;
 251
 252         ret = pcf8583_read_mem(client, &cmos_check);
 253         if (ret)
 254                 return ret;
 255
 256         ret = pcf8583_read_mem(client, &cmos_year);
 257         if (ret)
 258                 return ret;
 259
 260         chk -= year[1] + year[0];
 261
 262         year[1] = proper_year / 100;
 263         year[0] = proper_year % 100;
 264
 265         chk += year[1] + year[0];
 266
 267         ret = pcf8583_write_mem(client, &cmos_year);
 268
 269         if (ret)
 270                 return ret;
 271
 272         ret = pcf8583_write_mem(client, &cmos_check);
 273
 274         return ret;
 275 }
 276
 277 static const struct rtc_class_ops pcf8583_rtc_ops = {
 278         .read_time      = pcf8583_rtc_read_time,
 279         .set_time       = pcf8583_rtc_set_time,
 280 };
 281
 282 static int pcf8583_probe(struct i2c_adapter *adap, int addr, int kind);
 283
 284 static int pcf8583_attach(struct i2c_adapter *adap)
 285 {
 286         return i2c_probe(adap, &addr_data, pcf8583_probe);
 287 }
 288
 289 static int pcf8583_detach(struct i2c_client *client)
 290 {
 291         int err;
 292         struct pcf8583 *pcf = i2c_get_clientdata(client);
 293         struct rtc_device *rtc = pcf->rtc;
 294
 295         if (rtc)
 296                 rtc_device_unregister(rtc);
 297
 298         if ((err = i2c_detach_client(client)))
 299                 return err;
 300
 301         kfree(pcf);
 302         return 0;
 303 }
 304
 305 static struct i2c_driver pcf8583_driver = {
 306         .driver = {
 307                 .name   = "pcf8583",
 308         },
 309         .id             = I2C_DRIVERID_PCF8583,
 310         .attach_adapter = pcf8583_attach,
 311         .detach_client  = pcf8583_detach,
 312 };
 313
 314 static int pcf8583_probe(struct i2c_adapter *adap, int addr, int kind)
 315 {
 316         struct pcf8583 *pcf;
 317         struct i2c_client *client;
 318         struct rtc_device *rtc;
 319         unsigned char buf[1], ad[1] = { 0 };
 320         int err;
 321         struct i2c_msg msgs[2] = {
 322                 {
 323                         .addr = addr,
 324                         .flags = 0,
 325                         .len = 1,
 326                         .buf = ad,
 327                 }, {
 328                         .addr = addr,
 329                         .flags = I2C_M_RD,
 330                         .len = 1,
 331                         .buf = buf,
 332                 }
 333         };
 334
 335         if (!i2c_check_functionality(adap, I2C_FUNC_I2C))
 336                 return 0;
 337
 338         pcf = kzalloc(sizeof(*pcf), GFP_KERNEL);
 339         if (!pcf)
 340                 return -ENOMEM;
 341
 342         client = &pcf->client;
 343
 344         client->addr            = addr;
 345         client->adapter = adap;
 346         client->driver  = &pcf8583_driver;
 347
 348         strlcpy(client->name, pcf8583_driver.driver.name, I2C_NAME_SIZE);
 349
 350         if (i2c_transfer(client->adapter, msgs, 2) != 2) {
 351                 err = -EIO;
 352                 goto exit_kfree;
 353         }
 354
 355         err = i2c_attach_client(client);
 356
 357         if (err)
 358                 goto exit_kfree;
 359
 360         rtc = rtc_device_register(pcf8583_driver.driver.name, &client->dev,
 361                                   &pcf8583_rtc_ops, THIS_MODULE);
 362
 363         if (IS_ERR(rtc)) {
 364                 err = PTR_ERR(rtc);
 365                 goto exit_detach;
 366         }
 367
 368         pcf->rtc = rtc;
 369         i2c_set_clientdata(client, pcf);
 370         set_ctrl(client, buf[0]);
 371
 372         return 0;
 373
 374 exit_detach:
 375         i2c_detach_client(client);
 376
 377 exit_kfree:
 378         kfree(pcf);
 379
 380         return err;
 381 }
 382
 383 static __init int pcf8583_init(void)
 384 {
 385         return i2c_add_driver(&pcf8583_driver);
 386 }
 387
 388 static __exit void pcf8583_exit(void)
 389 {
 390         i2c_del_driver(&pcf8583_driver);
 391 }
 392
 393 module_init(pcf8583_init);
 394 module_exit(pcf8583_exit);
 395
 396 MODULE_AUTHOR("Russell King");
 397 MODULE_DESCRIPTION("PCF8583 I2C RTC driver");
 398 MODULE_LICENSE("GPL");