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/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 rtc_device *rtc;
  31         unsigned char ctrl;
  32 };
  33
  34 #define CTRL_STOP       0x80
  35 #define CTRL_HOLD       0x40
  36 #define CTRL_32KHZ      0x00
  37 #define CTRL_MASK       0x08
  38 #define CTRL_ALARMEN    0x04
  39 #define CTRL_ALARM      0x02
  40 #define CTRL_TIMER      0x01
  41
  42
  43 static struct i2c_driver pcf8583_driver;
  44
  45 #define get_ctrl(x)    ((struct pcf8583 *)i2c_get_clientdata(x))->ctrl
  46 #define set_ctrl(x, v) get_ctrl(x) = v
  47
  48 #define CMOS_YEAR       (64 + 128)
  49 #define CMOS_CHECKSUM   (63)
  50
  51 static int pcf8583_get_datetime(struct i2c_client *client, struct rtc_time *dt)
  52 {
  53         unsigned char buf[8], addr[1] = { 1 };
  54         struct i2c_msg msgs[2] = {
  55                 {
  56                         .addr = client->addr,
  57                         .flags = 0,
  58                         .len = 1,
  59                         .buf = addr,
  60                 }, {
  61                         .addr = client->addr,
  62                         .flags = I2C_M_RD,
  63                         .len = 6,
  64                         .buf = buf,
  65                 }
  66         };
  67         int ret;
  68
  69         memset(buf, 0, sizeof(buf));
  70
  71         ret = i2c_transfer(client->adapter, msgs, 2);
  72         if (ret == 2) {
  73                 dt->tm_year = buf[4] >> 6;
  74                 dt->tm_wday = buf[5] >> 5;
  75
  76                 buf[4] &= 0x3f;
  77                 buf[5] &= 0x1f;
  78
  79                 dt->tm_sec = bcd2bin(buf[1]);
  80                 dt->tm_min = bcd2bin(buf[2]);
  81                 dt->tm_hour = bcd2bin(buf[3]);
  82                 dt->tm_mday = bcd2bin(buf[4]);
  83                 dt->tm_mon = bcd2bin(buf[5]) - 1;
  84         }
  85
  86         return ret == 2 ? 0 : -EIO;
  87 }
  88
  89 static int pcf8583_set_datetime(struct i2c_client *client, struct rtc_time *dt, int datetoo)
  90 {
  91         unsigned char buf[8];
  92         int ret, len = 6;
  93
  94         buf[0] = 0;
  95         buf[1] = get_ctrl(client) | 0x80;
  96         buf[2] = 0;
  97         buf[3] = bin2bcd(dt->tm_sec);
  98         buf[4] = bin2bcd(dt->tm_min);
  99         buf[5] = bin2bcd(dt->tm_hour);
 100
 101         if (datetoo) {
 102                 len = 8;
 103                 buf[6] = bin2bcd(dt->tm_mday) | (dt->tm_year << 6);
 104                 buf[7] = bin2bcd(dt->tm_mon + 1)  | (dt->tm_wday << 5);
 105         }
 106
 107         ret = i2c_master_send(client, (char *)buf, len);
 108         if (ret != len)
 109                 return -EIO;
 110
 111         buf[1] = get_ctrl(client);
 112         ret = i2c_master_send(client, (char *)buf, 2);
 113
 114         return ret == 2 ? 0 : -EIO;
 115 }
 116
 117 static int pcf8583_get_ctrl(struct i2c_client *client, unsigned char *ctrl)
 118 {
 119         *ctrl = get_ctrl(client);
 120         return 0;
 121 }
 122
 123 static int pcf8583_set_ctrl(struct i2c_client *client, unsigned char *ctrl)
 124 {
 125         unsigned char buf[2];
 126
 127         buf[0] = 0;
 128         buf[1] = *ctrl;
 129         set_ctrl(client, *ctrl);
 130
 131         return i2c_master_send(client, (char *)buf, 2);
 132 }
 133
 134 static int pcf8583_read_mem(struct i2c_client *client, struct rtc_mem *mem)
 135 {
 136         unsigned char addr[1];
 137         struct i2c_msg msgs[2] = {
 138                 {
 139                         .addr = client->addr,
 140                         .flags = 0,
 141                         .len = 1,
 142                         .buf = addr,
 143                 }, {
 144                         .addr = client->addr,
 145                         .flags = I2C_M_RD,
 146                         .len = mem->nr,
 147                         .buf = mem->data,
 148                 }
 149         };
 150
 151         if (mem->loc < 8)
 152                 return -EINVAL;
 153
 154         addr[0] = mem->loc;
 155
 156         return i2c_transfer(client->adapter, msgs, 2) == 2 ? 0 : -EIO;
 157 }
 158
 159 static int pcf8583_write_mem(struct i2c_client *client, struct rtc_mem *mem)
 160 {
 161         unsigned char buf[9];
 162         int ret;
 163
 164         if (mem->loc < 8 || mem->nr > 8)
 165                 return -EINVAL;
 166
 167         buf[0] = mem->loc;
 168         memcpy(buf + 1, mem->data, mem->nr);
 169
 170         ret = i2c_master_send(client, buf, mem->nr + 1);
 171         return ret == mem->nr + 1 ? 0 : -EIO;
 172 }
 173
 174 static int pcf8583_rtc_read_time(struct device *dev, struct rtc_time *tm)
 175 {
 176         struct i2c_client *client = to_i2c_client(dev);
 177         unsigned char ctrl, year[2];
 178         struct rtc_mem mem = { CMOS_YEAR, sizeof(year), year };
 179         int real_year, year_offset, err;
 180
 181         /*
 182          * Ensure that the RTC is running.
 183          */
 184         pcf8583_get_ctrl(client, &ctrl);
 185         if (ctrl & (CTRL_STOP | CTRL_HOLD)) {
 186                 unsigned char new_ctrl = ctrl & ~(CTRL_STOP | CTRL_HOLD);
 187
 188                 dev_warn(dev, "resetting control %02x -> %02x\n",
 189                         ctrl, new_ctrl);
 190
 191                 err = pcf8583_set_ctrl(client, &new_ctrl);
 192                 if (err < 0)
 193                         return err;
 194         }
 195
 196         if (pcf8583_get_datetime(client, tm) ||
 197             pcf8583_read_mem(client, &mem))
 198                 return -EIO;
 199
 200         real_year = year[0];
 201
 202         /*
 203          * The RTC year holds the LSB two bits of the current
 204          * year, which should reflect the LSB two bits of the
 205          * CMOS copy of the year.  Any difference indicates
 206          * that we have to correct the CMOS version.
 207          */
 208         year_offset = tm->tm_year - (real_year & 3);
 209         if (year_offset < 0)
 210                 /*
 211                  * RTC year wrapped.  Adjust it appropriately.
 212                  */
 213                 year_offset += 4;
 214
 215         tm->tm_year = (real_year + year_offset + year[1] * 100) - 1900;
 216
 217         return 0;
 218 }
 219
 220 static int pcf8583_rtc_set_time(struct device *dev, struct rtc_time *tm)
 221 {
 222         struct i2c_client *client = to_i2c_client(dev);
 223         unsigned char year[2], chk;
 224         struct rtc_mem cmos_year  = { CMOS_YEAR, sizeof(year), year };
 225         struct rtc_mem cmos_check = { CMOS_CHECKSUM, 1, &chk };
 226         unsigned int proper_year = tm->tm_year + 1900;
 227         int ret;
 228
 229         /*
 230          * The RTC's own 2-bit year must reflect the least
 231          * significant two bits of the CMOS year.
 232          */
 233
 234         ret = pcf8583_set_datetime(client, tm, 1);
 235         if (ret)
 236                 return ret;
 237
 238         ret = pcf8583_read_mem(client, &cmos_check);
 239         if (ret)
 240                 return ret;
 241
 242         ret = pcf8583_read_mem(client, &cmos_year);
 243         if (ret)
 244                 return ret;
 245
 246         chk -= year[1] + year[0];
 247
 248         year[1] = proper_year / 100;
 249         year[0] = proper_year % 100;
 250
 251         chk += year[1] + year[0];
 252
 253         ret = pcf8583_write_mem(client, &cmos_year);
 254
 255         if (ret)
 256                 return ret;
 257
 258         ret = pcf8583_write_mem(client, &cmos_check);
 259
 260         return ret;
 261 }
 262
 263 static const struct rtc_class_ops pcf8583_rtc_ops = {
 264         .read_time      = pcf8583_rtc_read_time,
 265         .set_time       = pcf8583_rtc_set_time,
 266 };
 267
 268 static int pcf8583_probe(struct i2c_client *client,
 269                                 const struct i2c_device_id *id)
 270 {
 271         struct pcf8583 *pcf8583;
 272
 273         if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C))
 274                 return -ENODEV;
 275
 276         pcf8583 = devm_kzalloc(&client->dev, sizeof(struct pcf8583),
 277                                 GFP_KERNEL);
 278         if (!pcf8583)
 279                 return -ENOMEM;
 280
 281         i2c_set_clientdata(client, pcf8583);
 282
 283         pcf8583->rtc = devm_rtc_device_register(&client->dev,
 284                                 pcf8583_driver.driver.name,
 285                                 &pcf8583_rtc_ops, THIS_MODULE);
 286
 287         if (IS_ERR(pcf8583->rtc))
 288                 return PTR_ERR(pcf8583->rtc);
 289
 290         return 0;
 291 }
 292
 293 static const struct i2c_device_id pcf8583_id[] = {
 294         { "pcf8583", 0 },
 295         { }
 296 };
 297 MODULE_DEVICE_TABLE(i2c, pcf8583_id);
 298
 299 static struct i2c_driver pcf8583_driver = {
 300         .driver = {
 301                 .name   = "pcf8583",
 302                 .owner  = THIS_MODULE,
 303         },
 304         .probe          = pcf8583_probe,
 305         .id_table       = pcf8583_id,
 306 };
 307
 308 module_i2c_driver(pcf8583_driver);
 309
 310 MODULE_AUTHOR("Russell King");
 311 MODULE_DESCRIPTION("PCF8583 I2C RTC driver");
 312 MODULE_LICENSE("GPL");