[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
Greg Kroah-Hartman
parent
69dd204b6b
commit
c124a78d8c
4 changed files with 279 additions and 0 deletions
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@ -417,6 +417,17 @@ config SENSORS_DS1337
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This driver can also be built as a module. If so, the module
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will be called ds1337.
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config SENSORS_DS1374
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tristate "Maxim/Dallas Semiconductor DS1374 Real Time Clock"
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depends on I2C && EXPERIMENTAL
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select I2C_SENSOR
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help
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If you say yes here you get support for Dallas Semiconductor
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DS1374 real-time clock chips.
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This driver can also be built as a module. If so, the module
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will be called ds1374.
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config SENSORS_EEPROM
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tristate "EEPROM reader"
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depends on I2C && EXPERIMENTAL
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@ -14,6 +14,7 @@ obj-$(CONFIG_SENSORS_ADM1031) += adm1031.o
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obj-$(CONFIG_SENSORS_ADM9240) += adm9240.o
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obj-$(CONFIG_SENSORS_ATXP1) += atxp1.o
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obj-$(CONFIG_SENSORS_DS1337) += ds1337.o
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obj-$(CONFIG_SENSORS_DS1374) += ds1374.o
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obj-$(CONFIG_SENSORS_DS1621) += ds1621.o
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obj-$(CONFIG_SENSORS_EEPROM) += eeprom.o
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obj-$(CONFIG_SENSORS_FSCHER) += fscher.o
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266
drivers/i2c/chips/ds1374.c
Normal file
266
drivers/i2c/chips/ds1374.c
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@ -0,0 +1,266 @@
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/*
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* drivers/i2c/chips/ds1374.c
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*
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* I2C client/driver for the Maxim/Dallas DS1374 Real-Time Clock
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*
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* Author: Randy Vinson <rvinson@mvista.com>
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*
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* Based on the m41t00.c by Mark Greer <mgreer@mvista.com>
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*
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* 2005 (c) MontaVista Software, Inc. This file is licensed under
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* the terms of the GNU General Public License version 2. This program
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* is licensed "as is" without any warranty of any kind, whether express
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* or implied.
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*/
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/*
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* This i2c client/driver wedges between the drivers/char/genrtc.c RTC
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* interface and the SMBus interface of the i2c subsystem.
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* It would be more efficient to use i2c msgs/i2c_transfer directly but, as
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* recommened in .../Documentation/i2c/writing-clients section
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* "Sending and receiving", using SMBus level communication is preferred.
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*/
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#include <linux/kernel.h>
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#include <linux/module.h>
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#include <linux/interrupt.h>
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#include <linux/i2c.h>
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#include <linux/rtc.h>
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#include <linux/bcd.h>
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#include <asm/time.h>
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#include <asm/rtc.h>
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#define DS1374_REG_TOD0 0x00
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#define DS1374_REG_TOD1 0x01
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#define DS1374_REG_TOD2 0x02
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#define DS1374_REG_TOD3 0x03
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#define DS1374_REG_WDALM0 0x04
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#define DS1374_REG_WDALM1 0x05
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#define DS1374_REG_WDALM2 0x06
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#define DS1374_REG_CR 0x07
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#define DS1374_REG_SR 0x08
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#define DS1374_REG_SR_OSF 0x80
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#define DS1374_REG_TCR 0x09
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#define DS1374_DRV_NAME "ds1374"
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static DECLARE_MUTEX(ds1374_mutex);
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static struct i2c_driver ds1374_driver;
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static struct i2c_client *save_client;
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static unsigned short ignore[] = { I2C_CLIENT_END };
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static unsigned short normal_addr[] = { 0x68, I2C_CLIENT_END };
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static struct i2c_client_address_data addr_data = {
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.normal_i2c = normal_addr,
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.normal_i2c_range = ignore,
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.probe = ignore,
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.probe_range = ignore,
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.ignore = ignore,
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.ignore_range = ignore,
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.force = ignore,
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};
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static ulong ds1374_read_rtc(void)
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{
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ulong time = 0;
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int reg = DS1374_REG_WDALM0;
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while (reg--) {
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s32 tmp;
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if ((tmp = i2c_smbus_read_byte_data(save_client, reg)) < 0) {
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dev_warn(&save_client->dev,
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"can't read from rtc chip\n");
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return 0;
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}
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time = (time << 8) | (tmp & 0xff);
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}
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return time;
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}
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static void ds1374_write_rtc(ulong time)
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{
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int reg;
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for (reg = DS1374_REG_TOD0; reg < DS1374_REG_WDALM0; reg++) {
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if (i2c_smbus_write_byte_data(save_client, reg, time & 0xff)
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< 0) {
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dev_warn(&save_client->dev,
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"can't write to rtc chip\n");
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break;
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}
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time = time >> 8;
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}
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}
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static void ds1374_check_rtc_status(void)
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{
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s32 tmp;
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tmp = i2c_smbus_read_byte_data(save_client, DS1374_REG_SR);
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if (tmp < 0) {
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dev_warn(&save_client->dev,
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"can't read status from rtc chip\n");
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return;
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}
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if (tmp & DS1374_REG_SR_OSF) {
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dev_warn(&save_client->dev,
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"oscillator discontinuity flagged, time unreliable\n");
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tmp &= ~DS1374_REG_SR_OSF;
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tmp = i2c_smbus_write_byte_data(save_client, DS1374_REG_SR,
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tmp & 0xff);
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if (tmp < 0)
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dev_warn(&save_client->dev,
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"can't clear discontinuity notification\n");
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}
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}
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ulong ds1374_get_rtc_time(void)
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{
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ulong t1, t2;
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int limit = 10; /* arbitrary retry limit */
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down(&ds1374_mutex);
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/*
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* Since the reads are being performed one byte at a time using
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* the SMBus vs a 4-byte i2c transfer, there is a chance that a
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* carry will occur during the read. To detect this, 2 reads are
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* performed and compared.
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*/
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do {
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t1 = ds1374_read_rtc();
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t2 = ds1374_read_rtc();
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} while (t1 != t2 && limit--);
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up(&ds1374_mutex);
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if (t1 != t2) {
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dev_warn(&save_client->dev,
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"can't get consistent time from rtc chip\n");
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t1 = 0;
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}
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return t1;
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}
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static void ds1374_set_tlet(ulong arg)
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{
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ulong t1, t2;
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int limit = 10; /* arbitrary retry limit */
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t1 = *(ulong *) arg;
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down(&ds1374_mutex);
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/*
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* Since the writes are being performed one byte at a time using
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* the SMBus vs a 4-byte i2c transfer, there is a chance that a
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* carry will occur during the write. To detect this, the write
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* value is read back and compared.
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*/
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do {
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ds1374_write_rtc(t1);
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t2 = ds1374_read_rtc();
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} while (t1 != t2 && limit--);
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up(&ds1374_mutex);
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if (t1 != t2)
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dev_warn(&save_client->dev,
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"can't confirm time set from rtc chip\n");
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}
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ulong new_time;
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DECLARE_TASKLET_DISABLED(ds1374_tasklet, ds1374_set_tlet, (ulong) & new_time);
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int ds1374_set_rtc_time(ulong nowtime)
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{
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new_time = nowtime;
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if (in_interrupt())
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tasklet_schedule(&ds1374_tasklet);
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else
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ds1374_set_tlet((ulong) & new_time);
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return 0;
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}
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/*
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*****************************************************************************
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*
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* Driver Interface
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*
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*****************************************************************************
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*/
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static int ds1374_probe(struct i2c_adapter *adap, int addr, int kind)
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{
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struct i2c_client *client;
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int rc;
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client = kmalloc(sizeof(struct i2c_client), GFP_KERNEL);
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if (!client)
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return -ENOMEM;
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memset(client, 0, sizeof(struct i2c_client));
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strncpy(client->name, DS1374_DRV_NAME, I2C_NAME_SIZE);
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client->flags = I2C_DF_NOTIFY;
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client->addr = addr;
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client->adapter = adap;
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client->driver = &ds1374_driver;
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if ((rc = i2c_attach_client(client)) != 0) {
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kfree(client);
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return rc;
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}
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save_client = client;
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ds1374_check_rtc_status();
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return 0;
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}
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static int ds1374_attach(struct i2c_adapter *adap)
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{
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return i2c_probe(adap, &addr_data, ds1374_probe);
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}
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static int ds1374_detach(struct i2c_client *client)
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{
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int rc;
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if ((rc = i2c_detach_client(client)) == 0) {
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kfree(i2c_get_clientdata(client));
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tasklet_kill(&ds1374_tasklet);
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}
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return rc;
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}
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static struct i2c_driver ds1374_driver = {
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.owner = THIS_MODULE,
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.name = DS1374_DRV_NAME,
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.id = I2C_DRIVERID_DS1374,
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.flags = I2C_DF_NOTIFY,
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.attach_adapter = ds1374_attach,
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.detach_client = ds1374_detach,
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};
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static int __init ds1374_init(void)
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{
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return i2c_add_driver(&ds1374_driver);
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}
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static void __exit ds1374_exit(void)
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{
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i2c_del_driver(&ds1374_driver);
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}
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module_init(ds1374_init);
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module_exit(ds1374_exit);
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MODULE_AUTHOR("Randy Vinson <rvinson@mvista.com>");
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MODULE_DESCRIPTION("Maxim/Dallas DS1374 RTC I2C Client Driver");
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MODULE_LICENSE("GPL");
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@ -108,6 +108,7 @@
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#define I2C_DRIVERID_TDA7313 62 /* TDA7313 audio processor */
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#define I2C_DRIVERID_MAX6900 63 /* MAX6900 real-time clock */
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#define I2C_DRIVERID_SAA7114H 64 /* video decoder */
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#define I2C_DRIVERID_DS1374 65 /* DS1374 real time clock */
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#define I2C_DRIVERID_EXP0 0xF0 /* experimental use id's */
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