drivers/rtc/rtc-pcf8583.c

   1 /*
   2  *  drivers/rtc/rtc-pcf8583.c
   3  *
   4  *  Copyright (C) 2000 Russell King
   5  *  Copyright (C) 2008 Wolfram Sang & Juergen Beisert, Pengutronix
   6  *
   7  * This program is free software; you can redistribute it and/or modify
   8  * it under the terms of the GNU General Public License version 2 as
   9  * published by the Free Software Foundation.
  10  *
  11  *  Driver for PCF8583 RTC & RAM chip
  12  *
  13  *  Converted to the generic RTC susbsystem by G. Liakhovetski (2006)
  14  */
  15 #include <linux/module.h>
  16 #include <linux/i2c.h>
  17 #include <linux/slab.h>
  18 #include <linux/rtc.h>
  19 #include <linux/init.h>
  20 #include <linux/err.h>
  21 #include <linux/errno.h>
  22 #include <linux/bcd.h>
  23
  24 struct rtc_mem {
  25         unsigned int    loc;
  26         unsigned int    nr;
  27         unsigned char   *data;
  28 };
  29
  30 struct pcf8583 {
  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
  44 static struct i2c_driver pcf8583_driver;
  45
  46 #define get_ctrl(x)    ((struct pcf8583 *)i2c_get_clientdata(x))->ctrl
  47 #define set_ctrl(x, v) get_ctrl(x) = v
  48
  49 #define CMOS_YEAR       (64 + 128)
  50 #define CMOS_CHECKSUM   (63)
  51
  52 static int pcf8583_get_datetime(struct i2c_client *client, struct rtc_time *dt)
  53 {
  54         unsigned char buf[8], addr[1] = { 1 };
  55         struct i2c_msg msgs[2] = {
  56                 {
  57                         .addr = client->addr,
  58                         .flags = 0,
  59                         .len = 1,
  60                         .buf = addr,
  61                 }, {
  62                         .addr = client->addr,
  63                         .flags = I2C_M_RD,
  64                         .len = 6,
  65                         .buf = buf,
  66                 }
  67         };
  68         int ret;
  69
  70         memset(buf, 0, sizeof(buf));
  71
  72         ret = i2c_transfer(client->adapter, msgs, 2);
  73         if (ret == 2) {
  74                 dt->tm_year = buf[4] >> 6;
  75                 dt->tm_wday = buf[5] >> 5;
  76
  77                 buf[4] &= 0x3f;
  78                 buf[5] &= 0x1f;
  79
  80                 dt->tm_sec = bcd2bin(buf[1]);
  81                 dt->tm_min = bcd2bin(buf[2]);
  82                 dt->tm_hour = bcd2bin(buf[3]);
  83                 dt->tm_mday = bcd2bin(buf[4]);
  84                 dt->tm_mon = bcd2bin(buf[5]) - 1;
  85         }
  86
  87         return ret == 2 ? 0 : -EIO;
  88 }
  89
  90 static int pcf8583_set_datetime(struct i2c_client *client, struct rtc_time *dt, int datetoo)
  91 {
  92         unsigned char buf[8];
  93         int ret, len = 6;
  94
  95         buf[0] = 0;
  96         buf[1] = get_ctrl(client) | 0x80;
  97         buf[2] = 0;
  98         buf[3] = bin2bcd(dt->tm_sec);
  99         buf[4] = bin2bcd(dt->tm_min);
 100         buf[5] = bin2bcd(dt->tm_hour);
 101
 102         if (datetoo) {
 103                 len = 8;
 104                 buf[6] = bin2bcd(dt->tm_mday) | (dt->tm_year << 6);
 105                 buf[7] = bin2bcd(dt->tm_mon + 1)  | (dt->tm_wday << 5);
 106         }
 107
 108         ret = i2c_master_send(client, (char *)buf, len);
 109         if (ret != len)
 110                 return -EIO;
 111
 112         buf[1] = get_ctrl(client);
 113         ret = i2c_master_send(client, (char *)buf, 2);
 114
 115         return ret == 2 ? 0 : -EIO;
 116 }
 117
 118 static int pcf8583_get_ctrl(struct i2c_client *client, unsigned char *ctrl)
 119 {
 120         *ctrl = get_ctrl(client);
 121         return 0;
 122 }
 123
 124 static int pcf8583_set_ctrl(struct i2c_client *client, unsigned char *ctrl)
 125 {
 126         unsigned char buf[2];
 127
 128         buf[0] = 0;
 129         buf[1] = *ctrl;
 130         set_ctrl(client, *ctrl);
 131
 132         return i2c_master_send(client, (char *)buf, 2);
 133 }
 134
 135 static int pcf8583_read_mem(struct i2c_client *client, struct rtc_mem *mem)
 136 {
 137         unsigned char addr[1];
 138         struct i2c_msg msgs[2] = {
 139                 {
 140                         .addr = client->addr,
 141                         .flags = 0,
 142                         .len = 1,
 143                         .buf = addr,
 144                 }, {
 145                         .addr = client->addr,
 146                         .flags = I2C_M_RD,
 147                         .len = mem->nr,
 148                         .buf = mem->data,
 149                 }
 150         };
 151
 152         if (mem->loc < 8)
 153                 return -EINVAL;
 154
 155         addr[0] = mem->loc;
 156
 157         return i2c_transfer(client->adapter, msgs, 2) == 2 ? 0 : -EIO;
 158 }
 159
 160 static int pcf8583_write_mem(struct i2c_client *client, struct rtc_mem *mem)
 161 {
 162         unsigned char buf[9];
 163         int ret;
 164
 165         if (mem->loc < 8 || mem->nr > 8)
 166                 return -EINVAL;
 167
 168         buf[0] = mem->loc;
 169         memcpy(buf + 1, mem->data, mem->nr);
 170
 171         ret = i2c_master_send(client, buf, mem->nr + 1);
 172         return ret == mem->nr + 1 ? 0 : -EIO;
 173 }
 174
 175 static int pcf8583_rtc_read_time(struct device *dev, struct rtc_time *tm)
 176 {
 177         struct i2c_client *client = to_i2c_client(dev);
 178         unsigned char ctrl, year[2];
 179         struct rtc_mem mem = {
 180                 .loc = CMOS_YEAR,
 181                 .nr = sizeof(year),
 182                 .data = year
 183         };
 184         int real_year, year_offset, err;
 185
 186         /*
 187          * Ensure that the RTC is running.
 188          */
 189         pcf8583_get_ctrl(client, &ctrl);
 190         if (ctrl & (CTRL_STOP | CTRL_HOLD)) {
 191                 unsigned char new_ctrl = ctrl & ~(CTRL_STOP | CTRL_HOLD);
 192
 193                 dev_warn(dev, "resetting control %02x -> %02x\n",
 194                         ctrl, new_ctrl);
 195
 196                 err = pcf8583_set_ctrl(client, &new_ctrl);
 197                 if (err < 0)
 198                         return err;
 199         }
 200
 201         if (pcf8583_get_datetime(client, tm) ||
 202             pcf8583_read_mem(client, &mem))
 203                 return -EIO;
 204
 205         real_year = year[0];
 206
 207         /*
 208          * The RTC year holds the LSB two bits of the current
 209          * year, which should reflect the LSB two bits of the
 210          * CMOS copy of the year.  Any difference indicates
 211          * that we have to correct the CMOS version.
 212          */
 213         year_offset = tm->tm_year - (real_year & 3);
 214         if (year_offset < 0)
 215                 /*
 216                  * RTC year wrapped.  Adjust it appropriately.
 217                  */
 218                 year_offset += 4;
 219
 220         tm->tm_year = (real_year + year_offset + year[1] * 100) - 1900;
 221
 222         return 0;
 223 }
 224
 225 static int pcf8583_rtc_set_time(struct device *dev, struct rtc_time *tm)
 226 {
 227         struct i2c_client *client = to_i2c_client(dev);
 228         unsigned char year[2], chk;
 229         struct rtc_mem cmos_year  = {
 230                 .loc = CMOS_YEAR,
 231                 .nr = sizeof(year),
 232                 .data = year
 233         };
 234         struct rtc_mem cmos_check = {
 235                 .loc = CMOS_CHECKSUM,
 236                 .nr = 1,
 237                 .data = &chk
 238         };
 239         unsigned int proper_year = tm->tm_year + 1900;
 240         int ret;
 241
 242         /*
 243          * The RTC's own 2-bit year must reflect the least
 244          * significant two bits of the CMOS year.
 245          */
 246
 247         ret = pcf8583_set_datetime(client, tm, 1);
 248         if (ret)
 249                 return ret;
 250
 251         ret = pcf8583_read_mem(client, &cmos_check);
 252         if (ret)
 253                 return ret;
 254
 255         ret = pcf8583_read_mem(client, &cmos_year);
 256         if (ret)
 257                 return ret;
 258
 259         chk -= year[1] + year[0];
 260
 261         year[1] = proper_year / 100;
 262         year[0] = proper_year % 100;
 263
 264         chk += year[1] + year[0];
 265
 266         ret = pcf8583_write_mem(client, &cmos_year);
 267
 268         if (ret)
 269                 return ret;
 270
 271         ret = pcf8583_write_mem(client, &cmos_check);
 272
 273         return ret;
 274 }
 275
 276 static const struct rtc_class_ops pcf8583_rtc_ops = {
 277         .read_time      = pcf8583_rtc_read_time,
 278         .set_time       = pcf8583_rtc_set_time,
 279 };
 280
 281 static int pcf8583_probe(struct i2c_client *client,
 282                                 const struct i2c_device_id *id)
 283 {
 284         struct pcf8583 *pcf8583;
 285
 286         if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C))
 287                 return -ENODEV;
 288
 289         pcf8583 = devm_kzalloc(&client->dev, sizeof(struct pcf8583),
 290                                 GFP_KERNEL);
 291         if (!pcf8583)
 292                 return -ENOMEM;
 293
 294         i2c_set_clientdata(client, pcf8583);
 295
 296         pcf8583->rtc = devm_rtc_device_register(&client->dev,
 297                                 pcf8583_driver.driver.name,
 298                                 &pcf8583_rtc_ops, THIS_MODULE);
 299
 300         return PTR_ERR_OR_ZERO(pcf8583->rtc);
 301 }
 302
 303 static const struct i2c_device_id pcf8583_id[] = {
 304         { "pcf8583", 0 },
 305         { }
 306 };
 307 MODULE_DEVICE_TABLE(i2c, pcf8583_id);
 308
 309 static struct i2c_driver pcf8583_driver = {
 310         .driver = {
 311                 .name   = "pcf8583",
 312         },
 313         .probe          = pcf8583_probe,
 314         .id_table       = pcf8583_id,
 315 };
 316
 317 module_i2c_driver(pcf8583_driver);
 318
 319 MODULE_AUTHOR("Russell King");
 320 MODULE_DESCRIPTION("PCF8583 I2C RTC driver");
 321 MODULE_LICENSE("GPL");