[lm-sensors] Re: [PATCH 1/2] Add support for Maxim/Dallas DS1374 Real-Time Clock Chip

Kumar Gala kumar.gala at freescale.com
Fri Jun 3 23:41:34 CEST 2005


Randy,

I was planning on cloning the DS1337 driver once all of the latest  
patches for it got into Linus's tree.  Not sure if you looked at it,  
but when I was looking at RTC on 8349 the DS1337 seemed similar.  Not  
sure if we can unify the DS1337 driver such that can also support the  
DS1374.

(Also, I'll wait on acceptance of the driver before pushing the board  
code).

- kumar

On Jun 3, 2005, at 4:36 PM, Randy Vinson wrote:

> Greetings,
>   I've put together a small I2C client for the Maxim/Dallas DS1374 RTC
> chip and tested it on a Freescale MPC8349ADS board that uses the chip.
> The attached patch adds support for the chip itself and a follow-up  
> patch
> will add support to the Freescale board.
>
>   Please CC: me on any replies as I am not subscribed to the sensors  
> list.
>
> 		Thanks,
> 		Randy Vinson
>
>
> 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 at mvista.com>
>
> ---
> commit f95cc4d276cc332225bd823a2ae3be553c119990
> tree bd11f3262e29c13b6d56383415c634371394e913
> parent b56ae7a07ed0304bbc1dd61d3527dccdbcc467e9
> author Randy Vinson <rvinson at linuxbox.(none)> Fri, 03 Jun 2005  
> 13:50:59 -0700
> committer Randy Vinson <rvinson at linuxbox.(none)> Fri, 03 Jun 2005  
> 13:50:59 -0700
>
>  drivers/i2c/chips/Kconfig  |   11 ++
>  drivers/i2c/chips/Makefile |    1
>  drivers/i2c/chips/ds1374.c |  266  
> ++++++++++++++++++++++++++++++++++++++++++++
>  include/linux/i2c-id.h     |    1
>  4 files changed, 279 insertions(+), 0 deletions(-)
>
> diff --git a/drivers/i2c/chips/Kconfig b/drivers/i2c/chips/Kconfig
> --- a/drivers/i2c/chips/Kconfig
> +++ b/drivers/i2c/chips/Kconfig
> @@ -376,6 +376,17 @@ 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
> diff --git a/drivers/i2c/chips/Makefile b/drivers/i2c/chips/Makefile
> --- a/drivers/i2c/chips/Makefile
> +++ b/drivers/i2c/chips/Makefile
> @@ -12,6 +12,7 @@ obj-$(CONFIG_SENSORS_ADM1025)	+= adm1025
>  obj-$(CONFIG_SENSORS_ADM1026)	+= adm1026.o
>  obj-$(CONFIG_SENSORS_ADM1031)	+= adm1031.o
>  obj-$(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
> diff --git a/drivers/i2c/chips/ds1374.c b/drivers/i2c/chips/ds1374.c
> new file mode 100644
> --- /dev/null
> +++ b/drivers/i2c/chips/ds1374.c
> @@ -0,0 +1,266 @@
> +/*
> + * drivers/i2c/chips/ds1374.c
> + *
> + * I2C client/driver for the Maxim/Dallas DS1374 Real-Time Clock
> + *
> + * Author: Randy Vinson <rvinson at mvista.com>
> + *
> + * Based on the m41t00.c by Mark Greer <mgreer at 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 at mvista.com>");
> +MODULE_DESCRIPTION("Maxim/Dallas DS1374 RTC I2C Client Driver");
> +MODULE_LICENSE("GPL");
> diff --git a/include/linux/i2c-id.h b/include/linux/i2c-id.h
> --- a/include/linux/i2c-id.h
> +++ b/include/linux/i2c-id.h
> @@ -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	*/





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