linux/drivers/rtc/rtc-pcf8583.c
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   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
  23struct rtc_mem {
  24        unsigned int    loc;
  25        unsigned int    nr;
  26        unsigned char   *data;
  27};
  28
  29struct 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
  43static 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
  51static 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
  89static 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
 117static int pcf8583_get_ctrl(struct i2c_client *client, unsigned char *ctrl)
 118{
 119        *ctrl = get_ctrl(client);
 120        return 0;
 121}
 122
 123static 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
 134static 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
 159static 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
 174static 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                if ((err = pcf8583_set_ctrl(client, &new_ctrl)) < 0)
 192                        return err;
 193        }
 194
 195        if (pcf8583_get_datetime(client, tm) ||
 196            pcf8583_read_mem(client, &mem))
 197                return -EIO;
 198
 199        real_year = year[0];
 200
 201        /*
 202         * The RTC year holds the LSB two bits of the current
 203         * year, which should reflect the LSB two bits of the
 204         * CMOS copy of the year.  Any difference indicates
 205         * that we have to correct the CMOS version.
 206         */
 207        year_offset = tm->tm_year - (real_year & 3);
 208        if (year_offset < 0)
 209                /*
 210                 * RTC year wrapped.  Adjust it appropriately.
 211                 */
 212                year_offset += 4;
 213
 214        tm->tm_year = (real_year + year_offset + year[1] * 100) - 1900;
 215
 216        return 0;
 217}
 218
 219static int pcf8583_rtc_set_time(struct device *dev, struct rtc_time *tm)
 220{
 221        struct i2c_client *client = to_i2c_client(dev);
 222        unsigned char year[2], chk;
 223        struct rtc_mem cmos_year  = { CMOS_YEAR, sizeof(year), year };
 224        struct rtc_mem cmos_check = { CMOS_CHECKSUM, 1, &chk };
 225        unsigned int proper_year = tm->tm_year + 1900;
 226        int ret;
 227
 228        /*
 229         * The RTC's own 2-bit year must reflect the least
 230         * significant two bits of the CMOS year.
 231         */
 232
 233        ret = pcf8583_set_datetime(client, tm, 1);
 234        if (ret)
 235                return ret;
 236
 237        ret = pcf8583_read_mem(client, &cmos_check);
 238        if (ret)
 239                return ret;
 240
 241        ret = pcf8583_read_mem(client, &cmos_year);
 242        if (ret)
 243                return ret;
 244
 245        chk -= year[1] + year[0];
 246
 247        year[1] = proper_year / 100;
 248        year[0] = proper_year % 100;
 249
 250        chk += year[1] + year[0];
 251
 252        ret = pcf8583_write_mem(client, &cmos_year);
 253
 254        if (ret)
 255                return ret;
 256
 257        ret = pcf8583_write_mem(client, &cmos_check);
 258
 259        return ret;
 260}
 261
 262static const struct rtc_class_ops pcf8583_rtc_ops = {
 263        .read_time      = pcf8583_rtc_read_time,
 264        .set_time       = pcf8583_rtc_set_time,
 265};
 266
 267static int pcf8583_probe(struct i2c_client *client,
 268                                const struct i2c_device_id *id)
 269{
 270        struct pcf8583 *pcf8583;
 271        int err;
 272
 273        if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C))
 274                return -ENODEV;
 275
 276        pcf8583 = kzalloc(sizeof(struct pcf8583), GFP_KERNEL);
 277        if (!pcf8583)
 278                return -ENOMEM;
 279
 280        i2c_set_clientdata(client, pcf8583);
 281
 282        pcf8583->rtc = rtc_device_register(pcf8583_driver.driver.name,
 283                        &client->dev, &pcf8583_rtc_ops, THIS_MODULE);
 284
 285        if (IS_ERR(pcf8583->rtc)) {
 286                err = PTR_ERR(pcf8583->rtc);
 287                goto exit_kfree;
 288        }
 289
 290        return 0;
 291
 292exit_kfree:
 293        kfree(pcf8583);
 294        return err;
 295}
 296
 297static int pcf8583_remove(struct i2c_client *client)
 298{
 299        struct pcf8583 *pcf8583 = i2c_get_clientdata(client);
 300
 301        if (pcf8583->rtc)
 302                rtc_device_unregister(pcf8583->rtc);
 303        kfree(pcf8583);
 304        return 0;
 305}
 306
 307static const struct i2c_device_id pcf8583_id[] = {
 308        { "pcf8583", 0 },
 309        { }
 310};
 311MODULE_DEVICE_TABLE(i2c, pcf8583_id);
 312
 313static struct i2c_driver pcf8583_driver = {
 314        .driver = {
 315                .name   = "pcf8583",
 316                .owner  = THIS_MODULE,
 317        },
 318        .probe          = pcf8583_probe,
 319        .remove         = pcf8583_remove,
 320        .id_table       = pcf8583_id,
 321};
 322
 323module_i2c_driver(pcf8583_driver);
 324
 325MODULE_AUTHOR("Russell King");
 326MODULE_DESCRIPTION("PCF8583 I2C RTC driver");
 327MODULE_LICENSE("GPL");
 328
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