- 根目录:
- drivers
- rtc
- rtc-ds3232.c
/*
* RTC client/driver for the Maxim/Dallas DS3232 Real-Time Clock over I2C
*
* Copyright (C) 2009-2011 Freescale Semiconductor.
* Author: Jack Lan <jack.lan@freescale.com>
*
* This program is free software; you can redistribute it and/or modify it
* under the terms of the GNU General Public License as published by the
* Free Software Foundation; either version 2 of the License, or (at your
* option) any later version.
*/
/*
* It would be more efficient to use i2c msgs/i2c_transfer directly but, as
* recommened in .../Documentation/i2c/writing-clients section
* "Sending and receiving", using SMBus level communication is preferred.
*/
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/interrupt.h>
#include <linux/i2c.h>
#include <linux/rtc.h>
#include <linux/bcd.h>
#include <linux/workqueue.h>
#include <linux/slab.h>
#define DS3232_REG_SECONDS 0x00
#define DS3232_REG_MINUTES 0x01
#define DS3232_REG_HOURS 0x02
#define DS3232_REG_AMPM 0x02
#define DS3232_REG_DAY 0x03
#define DS3232_REG_DATE 0x04
#define DS3232_REG_MONTH 0x05
#define DS3232_REG_CENTURY 0x05
#define DS3232_REG_YEAR 0x06
#define DS3232_REG_ALARM1 0x07 /* Alarm 1 BASE */
#define DS3232_REG_ALARM2 0x0B /* Alarm 2 BASE */
#define DS3232_REG_CR 0x0E /* Control register */
# define DS3232_REG_CR_nEOSC 0x80
# define DS3232_REG_CR_INTCN 0x04
# define DS3232_REG_CR_A2IE 0x02
# define DS3232_REG_CR_A1IE 0x01
#define DS3232_REG_SR 0x0F /* control/status register */
# define DS3232_REG_SR_OSF 0x80
# define DS3232_REG_SR_BSY 0x04
# define DS3232_REG_SR_A2F 0x02
# define DS3232_REG_SR_A1F 0x01
struct ds3232 {
struct i2c_client *client;
struct rtc_device *rtc;
struct work_struct work;
/* The mutex protects alarm operations, and prevents a race
* between the enable_irq() in the workqueue and the free_irq()
* in the remove function.
*/
struct mutex mutex;
int exiting;
};
static struct i2c_driver ds3232_driver;
static int ds3232_check_rtc_status(struct i2c_client *client)
{
int ret = 0;
int control, stat;
stat = i2c_smbus_read_byte_data(client, DS3232_REG_SR);
if (stat < 0)
return stat;
if (stat & DS3232_REG_SR_OSF)
dev_warn(&client->dev,
"oscillator discontinuity flagged, "
"time unreliable\n");
stat &= ~(DS3232_REG_SR_OSF | DS3232_REG_SR_A1F | DS3232_REG_SR_A2F);
ret = i2c_smbus_write_byte_data(client, DS3232_REG_SR, stat);
if (ret < 0)
return ret;
/* If the alarm is pending, clear it before requesting
* the interrupt, so an interrupt event isn't reported
* before everything is initialized.
*/
control = i2c_smbus_read_byte_data(client, DS3232_REG_CR);
if (control < 0)
return control;
control &= ~(DS3232_REG_CR_A1IE | DS3232_REG_CR_A2IE);
control |= DS3232_REG_CR_INTCN;
return i2c_smbus_write_byte_data(client, DS3232_REG_CR, control);
}
static int ds3232_read_time(struct device *dev, struct rtc_time *time)
{
struct i2c_client *client = to_i2c_client(dev);
int ret;
u8 buf[7];
unsigned int year, month, day, hour, minute, second;
unsigned int week, twelve_hr, am_pm;
unsigned int century, add_century = 0;
ret = i2c_smbus_read_i2c_block_data(client, DS3232_REG_SECONDS, 7, buf);
if (ret < 0)
return ret;
if (ret < 7)
return -EIO;
second = buf[0];
minute = buf[1];
hour = buf[2];
week = buf[3];
day = buf[4];
month = buf[5];
year = buf[6];
/* Extract additional information for AM/PM and century */
twelve_hr = hour & 0x40;
am_pm = hour & 0x20;
century = month & 0x80;
/* Write to rtc_time structure */
time->tm_sec = bcd2bin(second);
time->tm_min = bcd2bin(minute);
if (twelve_hr) {
/* Convert to 24 hr */
if (am_pm)
time->tm_hour = bcd2bin(hour & 0x1F) + 12;
else
time->tm_hour = bcd2bin(hour & 0x1F);
} else {
time->tm_hour = bcd2bin(hour);
}
/* Day of the week in linux range is 0~6 while 1~7 in RTC chip */
time->tm_wday = bcd2bin(week) - 1;
time->tm_mday = bcd2bin(day);
/* linux tm_mon range:0~11, while month range is 1~12 in RTC chip */
time->tm_mon = bcd2bin(month & 0x7F) - 1;
if (century)
add_century = 100;
time->tm_year = bcd2bin(year) + add_century;
return rtc_valid_tm(time);
}
static int ds3232_set_time(struct device *dev, struct rtc_time *time)
{
struct i2c_client *client = to_i2c_client(dev);
u8 buf[7];
/* Extract time from rtc_time and load into ds3232*/
buf[0] = bin2bcd(time->tm_sec);
buf[1] = bin2bcd(time->tm_min);
buf[2] = bin2bcd(time->tm_hour);
/* Day of the week in linux range is 0~6 while 1~7 in RTC chip */
buf[3] = bin2bcd(time->tm_wday + 1);
buf[4] = bin2bcd(time->tm_mday); /* Date */
/* linux tm_mon range:0~11, while month range is 1~12 in RTC chip */
buf[5] = bin2bcd(time->tm_mon + 1);
if (time->tm_year >= 100) {
buf[5] |= 0x80;
buf[6] = bin2bcd(time->tm_year - 100);
} else {
buf[6] = bin2bcd(time->tm_year);
}
return i2c_smbus_write_i2c_block_data(client,
DS3232_REG_SECONDS, 7, buf);
}
/*
* DS3232 has two alarm, we only use alarm1
* According to linux specification, only support one-shot alarm
* no periodic alarm mode
*/
static int ds3232_read_alarm(struct device *dev, struct rtc_wkalrm *alarm)
{
struct i2c_client *client = to_i2c_client(dev);
struct ds3232 *ds3232 = i2c_get_clientdata(client);
int control, stat;
int ret;
u8 buf[4];
mutex_lock(&ds3232->mutex);
ret = i2c_smbus_read_byte_data(client, DS3232_REG_SR);
if (ret < 0)
goto out;
stat = ret;
ret = i2c_smbus_read_byte_data(client, DS3232_REG_CR);
if (ret < 0)
goto out;
control = ret;
ret = i2c_smbus_read_i2c_block_data(client, DS3232_REG_ALARM1, 4, buf);
if (ret < 0)
goto out;
alarm->time.tm_sec = bcd2bin(buf[0] & 0x7F);
alarm->time.tm_min = bcd2bin(buf[1] & 0x7F);
alarm->time.tm_hour = bcd2bin(buf[2] & 0x7F);
alarm->time.tm_mday = bcd2bin(buf[3] & 0x7F);
alarm->time.tm_mon = -1;
alarm->time.tm_year = -1;
alarm->time.tm_wday = -1;
alarm->time.tm_yday = -1;
alarm->time.tm_isdst = -1;
alarm->enabled = !!(control & DS3232_REG_CR_A1IE);
alarm->pending = !!(stat & DS3232_REG_SR_A1F);
ret = 0;
out:
mutex_unlock(&ds3232->mutex);
return ret;
}
/*
* linux rtc-module does not support wday alarm
* and only 24h time mode supported indeed
*/
static int ds3232_set_alarm(struct device *dev, struct rtc_wkalrm *alarm)
{
struct i2c_client *client = to_i2c_client(dev);
struct ds3232 *ds3232 = i2c_get_clientdata(client);
int control, stat;
int ret;
u8 buf[4];
if (client->irq <= 0)
return -EINVAL;
mutex_lock(&ds3232->mutex);
buf[0] = bin2bcd(alarm->time.tm_sec);
buf[1] = bin2bcd(alarm->time.tm_min);
buf[2] = bin2bcd(alarm->time.tm_hour);
buf[3] = bin2bcd(alarm->time.tm_mday);
/* clear alarm interrupt enable bit */
ret = i2c_smbus_read_byte_data(client, DS3232_REG_CR);
if (ret < 0)
goto out;
control = ret;
control &= ~(DS3232_REG_CR_A1IE | DS3232_REG_CR_A2IE);
ret = i2c_smbus_write_byte_data(client, DS3232_REG_CR, control);
if (ret < 0)
goto out;
/* clear any pending alarm flag */
ret = i2c_smbus_read_byte_data(client, DS3232_REG_SR);
if (ret < 0)
goto out;
stat = ret;
stat &= ~(DS3232_REG_SR_A1F | DS3232_REG_SR_A2F);
ret = i2c_smbus_write_byte_data(client, DS3232_REG_SR, stat);
if (ret < 0)
goto out;
ret = i2c_smbus_write_i2c_block_data(client, DS3232_REG_ALARM1, 4, buf);
if (alarm->enabled) {
control |= DS3232_REG_CR_A1IE;
ret = i2c_smbus_write_byte_data(client, DS3232_REG_CR, control);
}
out:
mutex_unlock(&ds3232->mutex);
return ret;
}
static void ds3232_update_alarm(struct i2c_client *client)
{
struct ds3232 *ds3232 = i2c_get_clientdata(client);
int control;
int ret;
u8 buf[4];
mutex_lock(&ds3232->mutex);
ret = i2c_smbus_read_i2c_block_data(client, DS3232_REG_ALARM1, 4, buf);
if (ret < 0)
goto unlock;
buf[0] = bcd2bin(buf[0]) < 0 || (ds3232->rtc->irq_data & RTC_UF) ?
0x80 : buf[0];
buf[1] = bcd2bin(buf[1]) < 0 || (ds3232->rtc->irq_data & RTC_UF) ?
0x80 : buf[1];
buf[2] = bcd2bin(buf[2]) < 0 || (ds3232->rtc->irq_data & RTC_UF) ?
0x80 : buf[2];
buf[3] = bcd2bin(buf[3]) < 0 || (ds3232->rtc->irq_data & RTC_UF) ?
0x80 : buf[3];
ret = i2c_smbus_write_i2c_block_data(client, DS3232_REG_ALARM1, 4, buf);
if (ret < 0)
goto unlock;
control = i2c_smbus_read_byte_data(client, DS3232_REG_CR);
if (control < 0)
goto unlock;
if (ds3232->rtc->irq_data & (RTC_AF | RTC_UF))
/* enable alarm1 interrupt */
control |= DS3232_REG_CR_A1IE;
else
/* disable alarm1 interrupt */
control &= ~(DS3232_REG_CR_A1IE);
i2c_smbus_write_byte_data(client, DS3232_REG_CR, control);
unlock:
mutex_unlock(&ds3232->mutex);
}
static int ds3232_alarm_irq_enable(struct device *dev, unsigned int enabled)
{
struct i2c_client *client = to_i2c_client(dev);
struct ds3232 *ds3232 = i2c_get_clientdata(client);
if (client->irq <= 0)
return -EINVAL;
if (enabled)
ds3232->rtc->irq_data |= RTC_AF;
else
ds3232->rtc->irq_data &= ~RTC_AF;
ds3232_update_alarm(client);
return 0;
}
static irqreturn_t ds3232_irq(int irq, void *dev_id)
{
struct i2c_client *client = dev_id;
struct ds3232 *ds3232 = i2c_get_clientdata(client);
disable_irq_nosync(irq);
schedule_work(&ds3232->work);
return IRQ_HANDLED;
}
static void ds3232_work(struct work_struct *work)
{
struct ds3232 *ds3232 = container_of(work, struct ds3232, work);
struct i2c_client *client = ds3232->client;
int stat, control;
mutex_lock(&ds3232->mutex);
stat = i2c_smbus_read_byte_data(client, DS3232_REG_SR);
if (stat < 0)
goto unlock;
if (stat & DS3232_REG_SR_A1F) {
control = i2c_smbus_read_byte_data(client, DS3232_REG_CR);
if (control < 0)
goto out;
/* disable alarm1 interrupt */
control &= ~(DS3232_REG_CR_A1IE);
i2c_smbus_write_byte_data(client, DS3232_REG_CR, control);
/* clear the alarm pend flag */
stat &= ~DS3232_REG_SR_A1F;
i2c_smbus_write_byte_data(client, DS3232_REG_SR, stat);
rtc_update_irq(ds3232->rtc, 1, RTC_AF | RTC_IRQF);
}
out:
if (!ds3232->exiting)
enable_irq(client->irq);
unlock:
mutex_unlock(&ds3232->mutex);
}
static const struct rtc_class_ops ds3232_rtc_ops = {
.read_time = ds3232_read_time,
.set_time = ds3232_set_time,
.read_alarm = ds3232_read_alarm,
.set_alarm = ds3232_set_alarm,
.alarm_irq_enable = ds3232_alarm_irq_enable,
};
static int __devinit ds3232_probe(struct i2c_client *client,
const struct i2c_device_id *id)
{
struct ds3232 *ds3232;
int ret;
ds3232 = kzalloc(sizeof(struct ds3232), GFP_KERNEL);
if (!ds3232)
return -ENOMEM;
ds3232->client = client;
i2c_set_clientdata(client, ds3232);
INIT_WORK(&ds3232->work, ds3232_work);
mutex_init(&ds3232->mutex);
ret = ds3232_check_rtc_status(client);
if (ret)
goto out_free;
ds3232->rtc = rtc_device_register(client->name, &client->dev,
&ds3232_rtc_ops, THIS_MODULE);
if (IS_ERR(ds3232->rtc)) {
ret = PTR_ERR(ds3232->rtc);
dev_err(&client->dev, "unable to register the class device\n");
goto out_irq;
}
if (client->irq >= 0) {
ret = request_irq(client->irq, ds3232_irq, 0,
"ds3232", client);
if (ret) {
dev_err(&client->dev, "unable to request IRQ\n");
goto out_free;
}
}
return 0;
out_irq:
if (client->irq >= 0)
free_irq(client->irq, client);
out_free:
kfree(ds3232);
return ret;
}
static int __devexit ds3232_remove(struct i2c_client *client)
{
struct ds3232 *ds3232 = i2c_get_clientdata(client);
if (client->irq >= 0) {
mutex_lock(&ds3232->mutex);
ds3232->exiting = 1;
mutex_unlock(&ds3232->mutex);
free_irq(client->irq, client);
cancel_work_sync(&ds3232->work);
}
rtc_device_unregister(ds3232->rtc);
kfree(ds3232);
return 0;
}
static const struct i2c_device_id ds3232_id[] = {
{ "ds3232", 0 },
{ }
};
MODULE_DEVICE_TABLE(i2c, ds3232_id);
static struct i2c_driver ds3232_driver = {
.driver = {
.name = "rtc-ds3232",
.owner = THIS_MODULE,
},
.probe = ds3232_probe,
.remove = __devexit_p(ds3232_remove),
.id_table = ds3232_id,
};
module_i2c_driver(ds3232_driver);
MODULE_AUTHOR("Srikanth Srinivasan <srikanth.srinivasan@freescale.com>");
MODULE_DESCRIPTION("Maxim/Dallas DS3232 RTC Driver");
MODULE_LICENSE("GPL");