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[PATCH] I2C: Add support for Maxim/Dallas DS1374 Real-Time Clock Chip (1/2) 

Add support for Maxim/Dallas DS1374 Real-Time Clock Chip

This change adds support for the Maxim/Dallas DS1374 RTC chip. This chip
is an I2C-based RTC that maintains a simple 32-bit binary seconds count
with battery backup support.

Signed-off-by: Randy Vinson <rvinson@mvista.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
This commit is contained in:
Randy Vinson 2005-06-03 14:36:06 -07:00 committed by Greg Kroah-Hartman
parent 69dd204b6b
commit c124a78d8c
4 changed files with 279 additions and 0 deletions
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11
drivers/i2c/chips/Kconfig
View File

@ -417,6 +417,17 @@ config SENSORS_DS1337
This driver can also be built as a module. If so, the module
will be called ds1337.
config SENSORS_DS1374
tristate "Maxim/Dallas Semiconductor DS1374 Real Time Clock"
depends on I2C && EXPERIMENTAL
select I2C_SENSOR
help
If you say yes here you get support for Dallas Semiconductor
DS1374 real-time clock chips.
This driver can also be built as a module. If so, the module
will be called ds1374.
config SENSORS_EEPROM
tristate "EEPROM reader"
depends on I2C && EXPERIMENTAL

1
drivers/i2c/chips/Makefile
View File

@ -14,6 +14,7 @@ obj-$(CONFIG_SENSORS_ADM1031) += adm1031.o
obj-$(CONFIG_SENSORS_ADM9240) += adm9240.o
obj-$(CONFIG_SENSORS_ATXP1) += atxp1.o
obj-$(CONFIG_SENSORS_DS1337) += ds1337.o
obj-$(CONFIG_SENSORS_DS1374) += ds1374.o
obj-$(CONFIG_SENSORS_DS1621) += ds1621.o
obj-$(CONFIG_SENSORS_EEPROM) += eeprom.o
obj-$(CONFIG_SENSORS_FSCHER) += fscher.o

266
drivers/i2c/chips/ds1374.c Normal file
View File

@ -0,0 +1,266 @@
/*
* drivers/i2c/chips/ds1374.c
*
* I2C client/driver for the Maxim/Dallas DS1374 Real-Time Clock
*
* Author: Randy Vinson <rvinson@mvista.com>
*
* Based on the m41t00.c by Mark 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 <asm/time.h>
#include <asm/rtc.h>
#define DS1374_REG_TOD0 0x00
#define DS1374_REG_TOD1 0x01
#define DS1374_REG_TOD2 0x02
#define DS1374_REG_TOD3 0x03
#define DS1374_REG_WDALM0 0x04
#define DS1374_REG_WDALM1 0x05
#define DS1374_REG_WDALM2 0x06
#define DS1374_REG_CR 0x07
#define DS1374_REG_SR 0x08
#define DS1374_REG_SR_OSF 0x80
#define DS1374_REG_TCR 0x09
#define DS1374_DRV_NAME "ds1374"
static DECLARE_MUTEX(ds1374_mutex);
static struct i2c_driver ds1374_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,
.normal_i2c_range = ignore,
.probe = ignore,
.probe_range = ignore,
.ignore = ignore,
.ignore_range = ignore,
.force = ignore,
};
static ulong ds1374_read_rtc(void)
{
ulong time = 0;
int reg = DS1374_REG_WDALM0;
while (reg--) {
s32 tmp;
if ((tmp = i2c_smbus_read_byte_data(save_client, reg)) < 0) {
dev_warn(&save_client->dev,
"can't read from rtc chip\n");
return 0;
}
time = (time << 8) | (tmp & 0xff);
}
return time;
}
static void ds1374_write_rtc(ulong time)
{
int reg;
for (reg = DS1374_REG_TOD0; reg < DS1374_REG_WDALM0; reg++) {
if (i2c_smbus_write_byte_data(save_client, reg, time & 0xff)
< 0) {
dev_warn(&save_client->dev,
"can't write to rtc chip\n");
break;
}
time = time >> 8;
}
}
static void ds1374_check_rtc_status(void)
{
s32 tmp;
tmp = i2c_smbus_read_byte_data(save_client, DS1374_REG_SR);
if (tmp < 0) {
dev_warn(&save_client->dev,
"can't read status from rtc chip\n");
return;
}
if (tmp & DS1374_REG_SR_OSF) {
dev_warn(&save_client->dev,
"oscillator discontinuity flagged, time unreliable\n");
tmp &= ~DS1374_REG_SR_OSF;
tmp = i2c_smbus_write_byte_data(save_client, DS1374_REG_SR,
tmp & 0xff);
if (tmp < 0)
dev_warn(&save_client->dev,
"can't clear discontinuity notification\n");
}
}
ulong ds1374_get_rtc_time(void)
{
ulong t1, t2;
int limit = 10; /* arbitrary retry limit */
down(&ds1374_mutex);
/*
* Since the reads are being performed one byte at a time using
* the SMBus vs a 4-byte i2c transfer, there is a chance that a
* carry will occur during the read. To detect this, 2 reads are
* performed and compared.
*/
do {
t1 = ds1374_read_rtc();
t2 = ds1374_read_rtc();
} while (t1 != t2 && limit--);
up(&ds1374_mutex);
if (t1 != t2) {
dev_warn(&save_client->dev,
"can't get consistent time from rtc chip\n");
t1 = 0;
}
return t1;
}
static void ds1374_set_tlet(ulong arg)
{
ulong t1, t2;
int limit = 10; /* arbitrary retry limit */
t1 = *(ulong *) arg;
down(&ds1374_mutex);
/*
* Since the writes are being performed one byte at a time using
* the SMBus vs a 4-byte i2c transfer, there is a chance that a
* carry will occur during the write. To detect this, the write
* value is read back and compared.
*/
do {
ds1374_write_rtc(t1);
t2 = ds1374_read_rtc();
} while (t1 != t2 && limit--);
up(&ds1374_mutex);
if (t1 != t2)
dev_warn(&save_client->dev,
"can't confirm time set from rtc chip\n");
}
ulong new_time;
DECLARE_TASKLET_DISABLED(ds1374_tasklet, ds1374_set_tlet, (ulong) & new_time);
int ds1374_set_rtc_time(ulong nowtime)
{
new_time = nowtime;
if (in_interrupt())
tasklet_schedule(&ds1374_tasklet);
else
ds1374_set_tlet((ulong) & new_time);
return 0;
}
/*
*****************************************************************************
*
* Driver Interface
*
*****************************************************************************
*/
static int ds1374_probe(struct i2c_adapter *adap, int addr, int kind)
{
struct i2c_client *client;
int rc;
client = kmalloc(sizeof(struct i2c_client), GFP_KERNEL);
if (!client)
return -ENOMEM;
memset(client, 0, sizeof(struct i2c_client));
strncpy(client->name, DS1374_DRV_NAME, I2C_NAME_SIZE);
client->flags = I2C_DF_NOTIFY;
client->addr = addr;
client->adapter = adap;
client->driver = &ds1374_driver;
if ((rc = i2c_attach_client(client)) != 0) {
kfree(client);
return rc;
}
save_client = client;
ds1374_check_rtc_status();
return 0;
}
static int ds1374_attach(struct i2c_adapter *adap)
{
return i2c_probe(adap, &addr_data, ds1374_probe);
}
static int ds1374_detach(struct i2c_client *client)
{
int rc;
if ((rc = i2c_detach_client(client)) == 0) {
kfree(i2c_get_clientdata(client));
tasklet_kill(&ds1374_tasklet);
}
return rc;
}
static struct i2c_driver ds1374_driver = {
.owner = THIS_MODULE,
.name = DS1374_DRV_NAME,
.id = I2C_DRIVERID_DS1374,
.flags = I2C_DF_NOTIFY,
.attach_adapter = ds1374_attach,
.detach_client = ds1374_detach,
};
static int __init ds1374_init(void)
{
return i2c_add_driver(&ds1374_driver);
}
static void __exit ds1374_exit(void)
{
i2c_del_driver(&ds1374_driver);
}
module_init(ds1374_init);
module_exit(ds1374_exit);
MODULE_AUTHOR("Randy Vinson <rvinson@mvista.com>");
MODULE_DESCRIPTION("Maxim/Dallas DS1374 RTC I2C Client Driver");
MODULE_LICENSE("GPL");

1
include/linux/i2c-id.h
View File

@ -108,6 +108,7 @@
#define I2C_DRIVERID_TDA7313 62 /* TDA7313 audio processor */
#define I2C_DRIVERID_MAX6900 63 /* MAX6900 real-time clock */
#define I2C_DRIVERID_SAA7114H 64 /* video decoder */
#define I2C_DRIVERID_DS1374 65 /* DS1374 real time clock */
#define I2C_DRIVERID_EXP0 0xF0 /* experimental use id's */