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/*
* drivers/i2c/chips/m41t00.c
*
* I2C client/driver for the ST M41T00 Real-Time Clock chip.
*
* Author: Mark A. Greer <mgreer@mvista.com>
*
* 2005 (c) MontaVista Software, Inc. This file is licensed under
* the terms of the GNU General Public License version 2. This program
* is licensed "as is" without any warranty of any kind, whether express
* or implied.
*/
/*
* This i2c client/driver wedges between the drivers/char/genrtc.c RTC
* interface and the SMBus interface of the i2c subsystem.
* 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/mutex.h>
#include <linux/workqueue.h>
#include <asm/time.h>
#include <asm/rtc.h>
#define M41T00_DRV_NAME "m41t00"
static DEFINE_MUTEX(m41t00_mutex);
static struct i2c_driver m41t00_driver;
static struct i2c_client *save_client;
static unsigned short ignore[] = { I2C_CLIENT_END };
static unsigned short normal_addr[] = { 0x68, I2C_CLIENT_END };
static struct i2c_client_address_data addr_data = {
.normal_i2c = normal_addr,
.probe = ignore,
.ignore = ignore,
};
ulong
m41t00_get_rtc_time(void)
{
s32 sec, min, hour, day, mon, year;
s32 sec1, min1, hour1, day1, mon1, year1;
ulong limit = 10;
sec = min = hour = day = mon = year = 0;
sec1 = min1 = hour1 = day1 = mon1 = year1 = 0;
mutex_lock(&m41t00_mutex);
do {
if (((sec = i2c_smbus_read_byte_data(save_client, 0)) >= 0)
&& ((min = i2c_smbus_read_byte_data(save_client, 1))
>= 0)
&& ((hour = i2c_smbus_read_byte_data(save_client, 2))
>= 0)
&& ((day = i2c_smbus_read_byte_data(save_client, 4))
>= 0)
&& ((mon = i2c_smbus_read_byte_data(save_client, 5))
>= 0)
&& ((year = i2c_smbus_read_byte_data(save_client, 6))
>= 0)
&& ((sec == sec1) && (min == min1) && (hour == hour1)
&& (day == day1) && (mon == mon1)
&& (year == year1)))
break;
sec1 = sec;
min1 = min;
hour1 = hour;
day1 = day;
mon1 = mon;
year1 = year;
} while (--limit > 0);
mutex_unlock(&m41t00_mutex);
if (limit == 0) {
dev_warn(&save_client->dev,
"m41t00: can't read rtc chip\n");
sec = min = hour = day = mon = year = 0;
}
sec &= 0x7f;
min &= 0x7f;
hour &= 0x3f;
day &= 0x3f;
mon &= 0x1f;
year &= 0xff;
BCD_TO_BIN(sec);
BCD_TO_BIN(min);
BCD_TO_BIN(hour);
BCD_TO_BIN(day);
BCD_TO_BIN(mon);
BCD_TO_BIN(year);
year += 1900;
if (year < 1970)
year += 100;
return mktime(year, mon, day, hour, min, sec);
}
static void
m41t00_set(void *arg)
{
struct rtc_time tm;
ulong nowtime = *(ulong *)arg;
to_tm(nowtime, &tm);
tm.tm_year = (tm.tm_year - 1900) % 100;
BIN_TO_BCD(tm.tm_sec);
BIN_TO_BCD(tm.tm_min);
BIN_TO_BCD(tm.tm_hour);
BIN_TO_BCD(tm.tm_mon);
BIN_TO_BCD(tm.tm_mday);
BIN_TO_BCD(tm.tm_year);
mutex_lock(&m41t00_mutex);
if ((i2c_smbus_write_byte_data(save_client, 0, tm.tm_sec & 0x7f) < 0)
|| (i2c_smbus_write_byte_data(save_client, 1, tm.tm_min & 0x7f)
< 0)
|| (i2c_smbus_write_byte_data(save_client, 2, tm.tm_hour & 0x7f)
< 0)
|| (i2c_smbus_write_byte_data(save_client, 4, tm.tm_mday & 0x7f)
< 0)
|| (i2c_smbus_write_byte_data(save_client, 5, tm.tm_mon & 0x7f)
< 0)
|| (i2c_smbus_write_byte_data(save_client, 6, tm.tm_year & 0x7f)
< 0))
dev_warn(&save_client->dev,"m41t00: can't write to rtc chip\n");
mutex_unlock(&m41t00_mutex);
return;
}
static ulong new_time;
static struct workqueue_struct *m41t00_wq;
static DECLARE_WORK(m41t00_work, m41t00_set, &new_time);
int
m41t00_set_rtc_time(ulong nowtime)
{
new_time = nowtime;
if (in_interrupt())
queue_work(m41t00_wq, &m41t00_work);
else
m41t00_set(&new_time);
return 0;
}
/*
*****************************************************************************
*
* Driver Interface
*
*****************************************************************************
*/
static int
m41t00_probe(struct i2c_adapter *adap, int addr, int kind)
{
struct i2c_client *client;
int rc;
client = kzalloc(sizeof(struct i2c_client), GFP_KERNEL);
if (!client)
return -ENOMEM;
strncpy(client->name, M41T00_DRV_NAME, I2C_NAME_SIZE);
client->addr = addr;
client->adapter = adap;
client->driver = &m41t00_driver;
if ((rc = i2c_attach_client(client)) != 0) {
kfree(client);
return rc;
}
m41t00_wq = create_singlethread_workqueue("m41t00");
save_client = client;
return 0;
}
static int
m41t00_attach(struct i2c_adapter *adap)
{
return i2c_probe(adap, &addr_data, m41t00_probe);
}
static int
m41t00_detach(struct i2c_client *client)
{
int rc;
if ((rc = i2c_detach_client(client)) == 0) {
kfree(client);
destroy_workqueue(m41t00_wq);
}
return rc;
}
static struct i2c_driver m41t00_driver = {
.driver = {
.name = M41T00_DRV_NAME,
},
.id = I2C_DRIVERID_STM41T00,
.attach_adapter = m41t00_attach,
.detach_client = m41t00_detach,
};
static int __init
m41t00_init(void)
{
return i2c_add_driver(&m41t00_driver);
}
static void __exit
m41t00_exit(void)
{
i2c_del_driver(&m41t00_driver);
return;
}
module_init(m41t00_init);
module_exit(m41t00_exit);
MODULE_AUTHOR("Mark A. Greer <mgreer@mvista.com>");
MODULE_DESCRIPTION("ST Microelectronics M41T00 RTC I2C Client Driver");
MODULE_LICENSE("GPL");
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