【问题】4412开发板配置pcf8563时钟芯片驱动后，无法使用，是什么问题呢？ - EDA365电子工程师网

驱动代码：
#include <linux/i2c.h>
#include <linux/bcd.h>
#include <linux/rtc.h>
#include <linux/slab.h>

#define DRV_VERSION "0.4.3"

#define PCF8563_REG_ST1             0x00 /* status */
#define PCF8563_REG_ST2             0x01

#define PCF8563_REG_SC             0x02 /* datetime */
#define PCF8563_REG_MN             0x03
#define PCF8563_REG_HR             0x04
#define PCF8563_REG_DM             0x05
#define PCF8563_REG_DW             0x06
#define PCF8563_REG_MO             0x07
#define PCF8563_REG_YR             0x08

#define PCF8563_REG_AMN             0x09 /* alarm */
#define PCF8563_REG_AHR             0x0A
#define PCF8563_REG_ADM             0x0B
#define PCF8563_REG_ADW             0x0C

#define PCF8563_REG_CLKO       0x0D /* clock out */
#define PCF8563_REG_TMRC       0x0E /* timer control */
#define PCF8563_REG_TMR             0x0F /* timer */

#define PCF8563_SC_LV             0x80 /* low voltage */
#define PCF8563_MO_C             0x80 /* century */

static struct i2c_driver pcf8563_driver;

struct pcf8563 {
      struct rtc_device *rtc;
      /*
      * The meaning of MO_C bit varies by the chip type.
      * From PCF8563 datasheet: this bit is toggled when the years
      * register overflows from 99 to 00
      * 0 indicates the century is 20xx
      * 1 indicates the century is 19xx
      * From RTC8564 datasheet: this bit indicates change of
      * century. When the year digit data overflows from 99 to 00,
      * this bit is set. By presetting it to 0 while still in the
      * 20th century, it will be set in year 2000, ...
      * There seems no reliable way to know how the system use this
      * bit.  So let's do it heuristically, assuming we are live in
      * 1970...2069.
      */
      int c_polarity;       /* 0: MO_C=1 means 19xx, otherwise MO_C=1 means 20xx */
};

/*
* In the routines that deal directly with the pcf8563 hardware, we use
* rtc_time -- month 0-11, hour 0-23, yr = calendar year-epoch.
*/
static int pcf8563_get_datetime(struct i2c_client *client, struct rtc_time *tm)
{
      struct pcf8563 *pcf8563 = i2c_get_clientdata(client);
      unsigned char buf[13] = { PCF8563_REG_ST1 };

      struct i2c_msg msgs[] = {
            { client->addr, 0, 1, buf },       /* setup read ptr */
            { client->addr, I2C_M_RD, 13, buf },       /* read status + date */
      };

      /* read registers */
      if ((i2c_transfer(client->adapter, msgs, 2)) != 2) {
            dev_err(&client->dev, "%s: read error\n", __func__);
            return -EIO;
      }

      if (buf[PCF8563_REG_SC] & PCF8563_SC_LV)
            dev_info(&client->dev,
                     "low voltage detected, date/time is not reliable.\n");

      dev_dbg(&client->dev,
            "%s: raw data is st1=%02x, st2=%02x, sec=%02x, min=%02x, hr=%02x, "
            "mday=%02x, wday=%02x, mon=%02x, year=%02x\n",
            __func__,
            buf[0], buf[1], buf[2], buf[3],
            buf[4], buf[5], buf[6], buf[7],
            buf[8]);

      tm->tm_sec = bcd2bin(buf[PCF8563_REG_SC] & 0x7F);
      tm->tm_min = bcd2bin(buf[PCF8563_REG_MN] & 0x7F);
      tm->tm_hour = bcd2bin(buf[PCF8563_REG_HR] & 0x3F); /* rtc hr 0-23 */
      tm->tm_mday = bcd2bin(buf[PCF8563_REG_DM] & 0x3F);
      tm->tm_wday = buf[PCF8563_REG_DW] & 0x07;
      tm->tm_mon = bcd2bin(buf[PCF8563_REG_MO] & 0x1F) - 1; /* rtc mn 1-12 */
      tm->tm_year = bcd2bin(buf[PCF8563_REG_YR]);
      if (tm->tm_year < 70)
            tm->tm_year += 100;       /* assume we are in 1970...2069 */
      /* detect the polarity heuristically. see note above. */
      pcf8563->c_polarity = (buf[PCF8563_REG_MO] & PCF8563_MO_C) ?
            (tm->tm_year >= 100) : (tm->tm_year < 100);

      dev_dbg(&client->dev, "%s: tm is secs=%d, mins=%d, hours=%d, "
            "mday=%d, mon=%d, year=%d, wday=%d\n",
            __func__,
            tm->tm_sec, tm->tm_min, tm->tm_hour,
            tm->tm_mday, tm->tm_mon, tm->tm_year, tm->tm_wday);

      /* the clock can give out invalid datetime, but we cannot return
      * -EINVAL otherwise hwclock will refuse to set the time on bootup.
      */
      if (rtc_valid_tm(tm) < 0)
            dev_err(&client->dev, "retrieved date/time is not valid.\n");

      return 0;
}

static int pcf8563_set_datetime(struct i2c_client *client, struct rtc_time *tm)
{
      struct pcf8563 *pcf8563 = i2c_get_clientdata(client);
      int i, err;
      unsigned char buf[9];

      dev_dbg(&client->dev, "%s: secs=%d, mins=%d, hours=%d, "
            "mday=%d, mon=%d, year=%d, wday=%d\n",
            __func__,
            tm->tm_sec, tm->tm_min, tm->tm_hour,
            tm->tm_mday, tm->tm_mon, tm->tm_year, tm->tm_wday);

      /* hours, minutes and seconds */
      buf[PCF8563_REG_SC] = bin2bcd(tm->tm_sec);
      buf[PCF8563_REG_MN] = bin2bcd(tm->tm_min);
      buf[PCF8563_REG_HR] = bin2bcd(tm->tm_hour);

      buf[PCF8563_REG_DM] = bin2bcd(tm->tm_mday);

      /* month, 1 - 12 */
      buf[PCF8563_REG_MO] = bin2bcd(tm->tm_mon + 1);

      /* year and century */
      buf[PCF8563_REG_YR] = bin2bcd(tm->tm_year % 100);
      if (pcf8563->c_polarity ? (tm->tm_year >= 100) : (tm->tm_year < 100))
            buf[PCF8563_REG_MO] |= PCF8563_MO_C;

      buf[PCF8563_REG_DW] = tm->tm_wday & 0x07;

      /* write register's data */
      for (i = 0; i < 7; i++) {
            unsigned char data[2] = { PCF8563_REG_SC + i,
                                             buf[PCF8563_REG_SC + i] };

            err = i2c_master_send(client, data, sizeof(data));
            if (err != sizeof(data)) {
                     dev_err(&client->dev,
                              "%s: err=%d addr=%02x, data=%02x\n",
                              __func__, err, data[0], data[1]);
                     return -EIO;
            }
      };

      return 0;
}

static int pcf8563_rtc_read_time(struct device *dev, struct rtc_time *tm)
{
      return pcf8563_get_datetime(to_i2c_client(dev), tm);
}

static int pcf8563_rtc_set_time(struct device *dev, struct rtc_time *tm)
{
      return pcf8563_set_datetime(to_i2c_client(dev), tm);
}

static const struct rtc_class_ops pcf8563_rtc_ops = {
      .read_time       = pcf8563_rtc_read_time,
      .set_time       = pcf8563_rtc_set_time,
};

static int pcf8563_probe(struct i2c_client *client,
                              const struct i2c_device_id *id)
{
      struct pcf8563 *pcf8563;

      int err = 0;

      dev_dbg(&client->dev, "%s\n", __func__);

      if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C))
            return -ENODEV;

      pcf8563 = kzalloc(sizeof(struct pcf8563), GFP_KERNEL);
      if (!pcf8563)
            return -ENOMEM;

      dev_info(&client->dev, "chip found, driver version " DRV_VERSION "\n");

      i2c_set_clientdata(client, pcf8563);

      pcf8563->rtc = rtc_device_register(pcf8563_driver.driver.name,
                              &client->dev, &pcf8563_rtc_ops, THIS_MODULE);

      if (IS_ERR(pcf8563->rtc)) {
            err = PTR_ERR(pcf8563->rtc);
            goto exit_kfree;
      }

      return 0;

exit_kfree:
      kfree(pcf8563);

      return err;
}

static int pcf8563_remove(struct i2c_client *client)
{
      struct pcf8563 *pcf8563 = i2c_get_clientdata(client);

      if (pcf8563->rtc)
            rtc_device_unregister(pcf8563->rtc);

      kfree(pcf8563);

      return 0;
}

static const struct i2c_device_id pcf8563_id[] = {
      { "pcf8563", 0 },
      { "rtc8564", 0 },
      { }
};
MODULE_DEVICE_TABLE(i2c, pcf8563_id);

static struct i2c_driver pcf8563_driver = {
      .driver             = {
            .name       = "rtc-pcf8563",
      },
      .probe             = pcf8563_probe,
      .remove             = pcf8563_remove,
      .id_table       = pcf8563_id,
};

static int __init pcf8563_init(void)
{
      return i2c_add_driver(&pcf8563_driver);
}

static void __exit pcf8563_exit(void)
{
      i2c_del_driver(&pcf8563_driver);
}

MODULE_AUTHOR("Alessandro Zummo <a.zummo@towertech.it>");
MODULE_DESCRIPTION("Philips PCF8563/Epson RTC8564 RTC driver");
MODULE_LICENSE("GPL");
MODULE_VERSION(DRV_VERSION);

module_init(pcf8563_init);
module_exit(pcf8563_exit);