LXR linux/drivers/rtc/rtc-pcf8523.c

   1/*
   2 * Copyright (C) 2012 Avionic Design GmbH
   3 *
   4 * This program is free software; you can redistribute it and/or modify
   5 * it under the terms of the GNU General Public License version 2 as
   6 * published by the Free Software Foundation.
   7 */
   8
   9#include <linux/bcd.h>
  10#include <linux/i2c.h>
  11#include <linux/module.h>
  12#include <linux/rtc.h>
  13#include <linux/of.h>
  14
  15#define DRIVER_NAME "rtc-pcf8523"
  16
  17#define REG_CONTROL1 0x00
  18#define REG_CONTROL1_CAP_SEL (1 << 7)
  19#define REG_CONTROL1_STOP    (1 << 5)
  20
  21#define REG_CONTROL3 0x02
  22#define REG_CONTROL3_PM_BLD (1 << 7) /* battery low detection disabled */
  23#define REG_CONTROL3_PM_VDD (1 << 6) /* switch-over disabled */
  24#define REG_CONTROL3_PM_DSM (1 << 5) /* direct switching mode */
  25#define REG_CONTROL3_PM_MASK 0xe0
  26#define REG_CONTROL3_BLF (1 << 2) /* battery low bit, read-only */
  27
  28#define REG_SECONDS  0x03
  29#define REG_SECONDS_OS (1 << 7)
  30
  31#define REG_MINUTES  0x04
  32#define REG_HOURS    0x05
  33#define REG_DAYS     0x06
  34#define REG_WEEKDAYS 0x07
  35#define REG_MONTHS   0x08
  36#define REG_YEARS    0x09
  37
  38struct pcf8523 {
  39        struct rtc_device *rtc;
  40};
  41
  42static int pcf8523_read(struct i2c_client *client, u8 reg, u8 *valuep)
  43{
  44        struct i2c_msg msgs[2];
  45        u8 value = 0;
  46        int err;
  47
  48        msgs[0].addr = client->addr;
  49        msgs[0].flags = 0;
  50        msgs[0].len = sizeof(reg);
  51        msgs[0].buf = &reg;
  52
  53        msgs[1].addr = client->addr;
  54        msgs[1].flags = I2C_M_RD;
  55        msgs[1].len = sizeof(value);
  56        msgs[1].buf = &value;
  57
  58        err = i2c_transfer(client->adapter, msgs, ARRAY_SIZE(msgs));
  59        if (err < 0)
  60                return err;
  61
  62        *valuep = value;
  63
  64        return 0;
  65}
  66
  67static int pcf8523_write(struct i2c_client *client, u8 reg, u8 value)
  68{
  69        u8 buffer[2] = { reg, value };
  70        struct i2c_msg msg;
  71        int err;
  72
  73        msg.addr = client->addr;
  74        msg.flags = 0;
  75        msg.len = sizeof(buffer);
  76        msg.buf = buffer;
  77
  78        err = i2c_transfer(client->adapter, &msg, 1);
  79        if (err < 0)
  80                return err;
  81
  82        return 0;
  83}
  84
  85static int pcf8523_select_capacitance(struct i2c_client *client, bool high)
  86{
  87        u8 value;
  88        int err;
  89
  90        err = pcf8523_read(client, REG_CONTROL1, &value);
  91        if (err < 0)
  92                return err;
  93
  94        if (!high)
  95                value &= ~REG_CONTROL1_CAP_SEL;
  96        else
  97                value |= REG_CONTROL1_CAP_SEL;
  98
  99        err = pcf8523_write(client, REG_CONTROL1, value);
 100        if (err < 0)
 101                return err;
 102
 103        return err;
 104}
 105
 106static int pcf8523_set_pm(struct i2c_client *client, u8 pm)
 107{
 108        u8 value;
 109        int err;
 110
 111        err = pcf8523_read(client, REG_CONTROL3, &value);
 112        if (err < 0)
 113                return err;
 114
 115        value = (value & ~REG_CONTROL3_PM_MASK) | pm;
 116
 117        err = pcf8523_write(client, REG_CONTROL3, value);
 118        if (err < 0)
 119                return err;
 120
 121        return 0;
 122}
 123
 124static int pcf8523_stop_rtc(struct i2c_client *client)
 125{
 126        u8 value;
 127        int err;
 128
 129        err = pcf8523_read(client, REG_CONTROL1, &value);
 130        if (err < 0)
 131                return err;
 132
 133        value |= REG_CONTROL1_STOP;
 134
 135        err = pcf8523_write(client, REG_CONTROL1, value);
 136        if (err < 0)
 137                return err;
 138
 139        return 0;
 140}
 141
 142static int pcf8523_start_rtc(struct i2c_client *client)
 143{
 144        u8 value;
 145        int err;
 146
 147        err = pcf8523_read(client, REG_CONTROL1, &value);
 148        if (err < 0)
 149                return err;
 150
 151        value &= ~REG_CONTROL1_STOP;
 152
 153        err = pcf8523_write(client, REG_CONTROL1, value);
 154        if (err < 0)
 155                return err;
 156
 157        return 0;
 158}
 159
 160static int pcf8523_rtc_read_time(struct device *dev, struct rtc_time *tm)
 161{
 162        struct i2c_client *client = to_i2c_client(dev);
 163        u8 start = REG_SECONDS, regs[7];
 164        struct i2c_msg msgs[2];
 165        int err;
 166
 167        msgs[0].addr = client->addr;
 168        msgs[0].flags = 0;
 169        msgs[0].len = 1;
 170        msgs[0].buf = &start;
 171
 172        msgs[1].addr = client->addr;
 173        msgs[1].flags = I2C_M_RD;
 174        msgs[1].len = sizeof(regs);
 175        msgs[1].buf = regs;
 176
 177        err = i2c_transfer(client->adapter, msgs, ARRAY_SIZE(msgs));
 178        if (err < 0)
 179                return err;
 180
 181        if (regs[0] & REG_SECONDS_OS)
 182                return -EINVAL;
 183
 184        tm->tm_sec = bcd2bin(regs[0] & 0x7f);
 185        tm->tm_min = bcd2bin(regs[1] & 0x7f);
 186        tm->tm_hour = bcd2bin(regs[2] & 0x3f);
 187        tm->tm_mday = bcd2bin(regs[3] & 0x3f);
 188        tm->tm_wday = regs[4] & 0x7;
 189        tm->tm_mon = bcd2bin(regs[5] & 0x1f) - 1;
 190        tm->tm_year = bcd2bin(regs[6]) + 100;
 191
 192        return rtc_valid_tm(tm);
 193}
 194
 195static int pcf8523_rtc_set_time(struct device *dev, struct rtc_time *tm)
 196{
 197        struct i2c_client *client = to_i2c_client(dev);
 198        struct i2c_msg msg;
 199        u8 regs[8];
 200        int err;
 201
 202        /*
 203         * The hardware can only store values between 0 and 99 in it's YEAR
 204         * register (with 99 overflowing to 0 on increment).
 205         * After 2100-02-28 we could start interpreting the year to be in the
 206         * interval [2100, 2199], but there is no path to switch in a smooth way
 207         * because the chip handles YEAR=0x00 (and the out-of-spec
 208         * YEAR=0xa0) as a leap year, but 2100 isn't.
 209         */
 210        if (tm->tm_year < 100 || tm->tm_year >= 200)
 211                return -EINVAL;
 212
 213        err = pcf8523_stop_rtc(client);
 214        if (err < 0)
 215                return err;
 216
 217        regs[0] = REG_SECONDS;
 218        /* This will purposely overwrite REG_SECONDS_OS */
 219        regs[1] = bin2bcd(tm->tm_sec);
 220        regs[2] = bin2bcd(tm->tm_min);
 221        regs[3] = bin2bcd(tm->tm_hour);
 222        regs[4] = bin2bcd(tm->tm_mday);
 223        regs[5] = tm->tm_wday;
 224        regs[6] = bin2bcd(tm->tm_mon + 1);
 225        regs[7] = bin2bcd(tm->tm_year - 100);
 226
 227        msg.addr = client->addr;
 228        msg.flags = 0;
 229        msg.len = sizeof(regs);
 230        msg.buf = regs;
 231
 232        err = i2c_transfer(client->adapter, &msg, 1);
 233        if (err < 0) {
 234                /*
 235                 * If the time cannot be set, restart the RTC anyway. Note
 236                 * that errors are ignored if the RTC cannot be started so
 237                 * that we have a chance to propagate the original error.
 238                 */
 239                pcf8523_start_rtc(client);
 240                return err;
 241        }
 242
 243        return pcf8523_start_rtc(client);
 244}
 245
 246#ifdef CONFIG_RTC_INTF_DEV
 247static int pcf8523_rtc_ioctl(struct device *dev, unsigned int cmd,
 248                             unsigned long arg)
 249{
 250        struct i2c_client *client = to_i2c_client(dev);
 251        u8 value;
 252        int ret = 0, err;
 253
 254        switch (cmd) {
 255        case RTC_VL_READ:
 256                err = pcf8523_read(client, REG_CONTROL3, &value);
 257                if (err < 0)
 258                        return err;
 259
 260                if (value & REG_CONTROL3_BLF)
 261                        ret = 1;
 262
 263                if (copy_to_user((void __user *)arg, &ret, sizeof(int)))
 264                        return -EFAULT;
 265
 266                return 0;
 267        default:
 268                return -ENOIOCTLCMD;
 269        }
 270}
 271#else
 272#define pcf8523_rtc_ioctl NULL
 273#endif
 274
 275static const struct rtc_class_ops pcf8523_rtc_ops = {
 276        .read_time = pcf8523_rtc_read_time,
 277        .set_time = pcf8523_rtc_set_time,
 278        .ioctl = pcf8523_rtc_ioctl,
 279};
 280
 281static int pcf8523_probe(struct i2c_client *client,
 282                         const struct i2c_device_id *id)
 283{
 284        struct pcf8523 *pcf;
 285        int err;
 286
 287        if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C))
 288                return -ENODEV;
 289
 290        pcf = devm_kzalloc(&client->dev, sizeof(*pcf), GFP_KERNEL);
 291        if (!pcf)
 292                return -ENOMEM;
 293
 294        err = pcf8523_select_capacitance(client, true);
 295        if (err < 0)
 296                return err;
 297
 298        err = pcf8523_set_pm(client, 0);
 299        if (err < 0)
 300                return err;
 301
 302        pcf->rtc = devm_rtc_device_register(&client->dev, DRIVER_NAME,
 303                                       &pcf8523_rtc_ops, THIS_MODULE);
 304        if (IS_ERR(pcf->rtc))
 305                return PTR_ERR(pcf->rtc);
 306
 307        i2c_set_clientdata(client, pcf);
 308
 309        return 0;
 310}
 311
 312static const struct i2c_device_id pcf8523_id[] = {
 313        { "pcf8523", 0 },
 314        { }
 315};
 316MODULE_DEVICE_TABLE(i2c, pcf8523_id);
 317
 318#ifdef CONFIG_OF
 319static const struct of_device_id pcf8523_of_match[] = {
 320        { .compatible = "nxp,pcf8523" },
 321        { }
 322};
 323MODULE_DEVICE_TABLE(of, pcf8523_of_match);
 324#endif
 325
 326static struct i2c_driver pcf8523_driver = {
 327        .driver = {
 328                .name = DRIVER_NAME,
 329                .of_match_table = of_match_ptr(pcf8523_of_match),
 330        },
 331        .probe = pcf8523_probe,
 332        .id_table = pcf8523_id,
 333};
 334module_i2c_driver(pcf8523_driver);
 335
 336MODULE_AUTHOR("Thierry Reding <thierry.reding@avionic-design.de>");
 337MODULE_DESCRIPTION("NXP PCF8523 RTC driver");
 338MODULE_LICENSE("GPL v2");
 339