[PATCH] I2C: Add support for Maxim/Dallas DS1374 Real-Time Clock Chip (1/2) (c124a78d) · Commits · 戴 / test

drivers/i2c/chips/Kconfig

+11 −0

Original line number	Diff line number	Diff line
		@@ -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

drivers/i2c/chips/Makefile

+1 −0

Original line number	Diff line number	Diff line
		@@ -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

drivers/i2c/chips/ds1374.c

0 → 100644

+266 −0

Original line number	Diff line number	Diff line
		/*
		* 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");

include/linux/i2c-id.h

+1 −0

Original line number	Diff line number	Diff line
		@@ -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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