370 lines
8.3 KiB
C
370 lines
8.3 KiB
C
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/*
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* PCF8563 RTC
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*
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* From Phillips' datasheet:
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*
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* The PCF8563 is a CMOS real-time clock/calendar optimized for low power
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* consumption. A programmable clock output, interrupt output and voltage
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* low detector are also provided. All address and data are transferred
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* serially via two-line bidirectional I2C-bus. Maximum bus speed is
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* 400 kbits/s. The built-in word address register is incremented
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* automatically after each written or read byte.
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*
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* Copyright (c) 2002-2007, Axis Communications AB
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* All rights reserved.
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*
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* Author: Tobias Anderberg <tobiasa@axis.com>.
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*
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*/
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#include <linux/module.h>
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#include <linux/kernel.h>
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#include <linux/types.h>
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#include <linux/sched.h>
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#include <linux/init.h>
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#include <linux/fs.h>
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#include <linux/ioctl.h>
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#include <linux/delay.h>
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#include <linux/bcd.h>
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#include <linux/mutex.h>
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#include <asm/uaccess.h>
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#include <asm/system.h>
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#include <asm/io.h>
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#include <asm/rtc.h>
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#include "i2c.h"
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#define PCF8563_MAJOR 121 /* Local major number. */
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#define DEVICE_NAME "rtc" /* Name which is registered in /proc/devices. */
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#define PCF8563_NAME "PCF8563"
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#define DRIVER_VERSION "$Revision: 1.24 $"
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/* I2C bus slave registers. */
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#define RTC_I2C_READ 0xa3
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#define RTC_I2C_WRITE 0xa2
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/* Two simple wrapper macros, saves a few keystrokes. */
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#define rtc_read(x) i2c_readreg(RTC_I2C_READ, x)
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#define rtc_write(x,y) i2c_writereg(RTC_I2C_WRITE, x, y)
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static DEFINE_MUTEX(rtc_lock); /* Protect state etc */
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static const unsigned char days_in_month[] =
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{ 0, 31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31 };
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int pcf8563_ioctl(struct inode *, struct file *, unsigned int, unsigned long);
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/* Cache VL bit value read at driver init since writing the RTC_SECOND
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* register clears the VL status.
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*/
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static int voltage_low;
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static const struct file_operations pcf8563_fops = {
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.owner = THIS_MODULE,
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.ioctl = pcf8563_ioctl,
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};
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unsigned char
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pcf8563_readreg(int reg)
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{
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unsigned char res = rtc_read(reg);
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/* The PCF8563 does not return 0 for unimplemented bits. */
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switch (reg) {
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case RTC_SECONDS:
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case RTC_MINUTES:
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res &= 0x7F;
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break;
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case RTC_HOURS:
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case RTC_DAY_OF_MONTH:
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res &= 0x3F;
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break;
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case RTC_WEEKDAY:
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res &= 0x07;
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break;
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case RTC_MONTH:
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res &= 0x1F;
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break;
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case RTC_CONTROL1:
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res &= 0xA8;
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break;
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case RTC_CONTROL2:
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res &= 0x1F;
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break;
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case RTC_CLOCKOUT_FREQ:
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case RTC_TIMER_CONTROL:
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res &= 0x83;
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break;
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}
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return res;
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}
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void
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pcf8563_writereg(int reg, unsigned char val)
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{
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rtc_write(reg, val);
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}
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void
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get_rtc_time(struct rtc_time *tm)
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{
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tm->tm_sec = rtc_read(RTC_SECONDS);
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tm->tm_min = rtc_read(RTC_MINUTES);
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tm->tm_hour = rtc_read(RTC_HOURS);
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tm->tm_mday = rtc_read(RTC_DAY_OF_MONTH);
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tm->tm_wday = rtc_read(RTC_WEEKDAY);
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tm->tm_mon = rtc_read(RTC_MONTH);
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tm->tm_year = rtc_read(RTC_YEAR);
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if (tm->tm_sec & 0x80) {
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printk(KERN_ERR "%s: RTC Voltage Low - reliable date/time "
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"information is no longer guaranteed!\n", PCF8563_NAME);
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}
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tm->tm_year = bcd2bin(tm->tm_year) +
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((tm->tm_mon & 0x80) ? 100 : 0);
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tm->tm_sec &= 0x7F;
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tm->tm_min &= 0x7F;
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tm->tm_hour &= 0x3F;
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tm->tm_mday &= 0x3F;
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tm->tm_wday &= 0x07; /* Not coded in BCD. */
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tm->tm_mon &= 0x1F;
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tm->tm_sec = bcd2bin(tm->tm_sec);
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tm->tm_min = bcd2bin(tm->tm_min);
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tm->tm_hour = bcd2bin(tm->tm_hour);
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tm->tm_mday = bcd2bin(tm->tm_mday);
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tm->tm_mon = bcd2bin(tm->tm_mon);
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tm->tm_mon--; /* Month is 1..12 in RTC but 0..11 in linux */
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}
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int __init
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pcf8563_init(void)
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{
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static int res;
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static int first = 1;
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if (!first)
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return res;
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first = 0;
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/* Initiate the i2c protocol. */
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res = i2c_init();
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if (res < 0) {
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printk(KERN_CRIT "pcf8563_init: Failed to init i2c.\n");
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return res;
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}
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/*
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* First of all we need to reset the chip. This is done by
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* clearing control1, control2 and clk freq and resetting
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* all alarms.
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*/
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if (rtc_write(RTC_CONTROL1, 0x00) < 0)
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goto err;
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if (rtc_write(RTC_CONTROL2, 0x00) < 0)
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goto err;
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if (rtc_write(RTC_CLOCKOUT_FREQ, 0x00) < 0)
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goto err;
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if (rtc_write(RTC_TIMER_CONTROL, 0x03) < 0)
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goto err;
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/* Reset the alarms. */
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if (rtc_write(RTC_MINUTE_ALARM, 0x80) < 0)
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goto err;
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if (rtc_write(RTC_HOUR_ALARM, 0x80) < 0)
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goto err;
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if (rtc_write(RTC_DAY_ALARM, 0x80) < 0)
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goto err;
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if (rtc_write(RTC_WEEKDAY_ALARM, 0x80) < 0)
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goto err;
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/* Check for low voltage, and warn about it. */
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if (rtc_read(RTC_SECONDS) & 0x80) {
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voltage_low = 1;
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printk(KERN_WARNING "%s: RTC Voltage Low - reliable "
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"date/time information is no longer guaranteed!\n",
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PCF8563_NAME);
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}
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return res;
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err:
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printk(KERN_INFO "%s: Error initializing chip.\n", PCF8563_NAME);
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res = -1;
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return res;
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}
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void __exit
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pcf8563_exit(void)
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{
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unregister_chrdev(PCF8563_MAJOR, DEVICE_NAME);
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}
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/*
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* ioctl calls for this driver. Why return -ENOTTY upon error? Because
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* POSIX says so!
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*/
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int pcf8563_ioctl(struct inode *inode, struct file *filp, unsigned int cmd,
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unsigned long arg)
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{
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/* Some sanity checks. */
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if (_IOC_TYPE(cmd) != RTC_MAGIC)
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return -ENOTTY;
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if (_IOC_NR(cmd) > RTC_MAX_IOCTL)
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return -ENOTTY;
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switch (cmd) {
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case RTC_RD_TIME:
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{
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struct rtc_time tm;
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mutex_lock(&rtc_lock);
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memset(&tm, 0, sizeof tm);
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get_rtc_time(&tm);
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if (copy_to_user((struct rtc_time *) arg, &tm,
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sizeof tm)) {
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mutex_unlock(&rtc_lock);
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return -EFAULT;
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}
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mutex_unlock(&rtc_lock);
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return 0;
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}
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case RTC_SET_TIME:
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{
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int leap;
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int year;
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int century;
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struct rtc_time tm;
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memset(&tm, 0, sizeof tm);
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if (!capable(CAP_SYS_TIME))
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return -EPERM;
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if (copy_from_user(&tm, (struct rtc_time *) arg, sizeof tm))
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return -EFAULT;
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/* Convert from struct tm to struct rtc_time. */
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tm.tm_year += 1900;
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tm.tm_mon += 1;
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/*
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* Check if tm.tm_year is a leap year. A year is a leap
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* year if it is divisible by 4 but not 100, except
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* that years divisible by 400 _are_ leap years.
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*/
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year = tm.tm_year;
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leap = (tm.tm_mon == 2) &&
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((year % 4 == 0 && year % 100 != 0) || year % 400 == 0);
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/* Perform some sanity checks. */
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if ((tm.tm_year < 1970) ||
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(tm.tm_mon > 12) ||
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(tm.tm_mday == 0) ||
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(tm.tm_mday > days_in_month[tm.tm_mon] + leap) ||
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(tm.tm_wday >= 7) ||
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(tm.tm_hour >= 24) ||
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(tm.tm_min >= 60) ||
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(tm.tm_sec >= 60))
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return -EINVAL;
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century = (tm.tm_year >= 2000) ? 0x80 : 0;
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tm.tm_year = tm.tm_year % 100;
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tm.tm_year = bin2bcd(tm.tm_year);
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tm.tm_mon = bin2bcd(tm.tm_mon);
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tm.tm_mday = bin2bcd(tm.tm_mday);
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tm.tm_hour = bin2bcd(tm.tm_hour);
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tm.tm_min = bin2bcd(tm.tm_min);
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tm.tm_sec = bin2bcd(tm.tm_sec);
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tm.tm_mon |= century;
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mutex_lock(&rtc_lock);
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rtc_write(RTC_YEAR, tm.tm_year);
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rtc_write(RTC_MONTH, tm.tm_mon);
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rtc_write(RTC_WEEKDAY, tm.tm_wday); /* Not coded in BCD. */
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rtc_write(RTC_DAY_OF_MONTH, tm.tm_mday);
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rtc_write(RTC_HOURS, tm.tm_hour);
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rtc_write(RTC_MINUTES, tm.tm_min);
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rtc_write(RTC_SECONDS, tm.tm_sec);
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mutex_unlock(&rtc_lock);
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return 0;
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}
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case RTC_VL_READ:
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if (voltage_low) {
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printk(KERN_ERR "%s: RTC Voltage Low - "
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"reliable date/time information is no "
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"longer guaranteed!\n", PCF8563_NAME);
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}
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if (copy_to_user((int *) arg, &voltage_low, sizeof(int)))
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return -EFAULT;
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return 0;
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case RTC_VL_CLR:
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{
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/* Clear the VL bit in the seconds register in case
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* the time has not been set already (which would
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* have cleared it). This does not really matter
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* because of the cached voltage_low value but do it
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* anyway for consistency. */
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int ret = rtc_read(RTC_SECONDS);
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rtc_write(RTC_SECONDS, (ret & 0x7F));
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/* Clear the cached value. */
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voltage_low = 0;
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return 0;
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}
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default:
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return -ENOTTY;
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}
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return 0;
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}
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static int __init pcf8563_register(void)
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{
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if (pcf8563_init() < 0) {
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printk(KERN_INFO "%s: Unable to initialize Real-Time Clock "
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"Driver, %s\n", PCF8563_NAME, DRIVER_VERSION);
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return -1;
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}
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if (register_chrdev(PCF8563_MAJOR, DEVICE_NAME, &pcf8563_fops) < 0) {
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printk(KERN_INFO "%s: Unable to get major number %d for RTC device.\n",
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PCF8563_NAME, PCF8563_MAJOR);
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return -1;
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}
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printk(KERN_INFO "%s Real-Time Clock Driver, %s\n", PCF8563_NAME,
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DRIVER_VERSION);
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/* Check for low voltage, and warn about it. */
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if (voltage_low) {
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printk(KERN_WARNING "%s: RTC Voltage Low - reliable date/time "
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"information is no longer guaranteed!\n", PCF8563_NAME);
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}
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return 0;
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}
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module_init(pcf8563_register);
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module_exit(pcf8563_exit);
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