Greg KH
2005-06-22T10:17:19Z

[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>

---
commit c124a78d8c7475ecc43f385f34112b638c4228d9
tree 46de795c5e2da258a54501658f74e9619c271527
parent 69dd204b6b45987dbf9ce7058cd238d355865281
author Randy Vinson <rvinson@mvista.com> Fri, 03 Jun 2005 14:36:06 -0700
committer Greg Kroah-Hartman <gregkh@suse.de> Tue, 21 Jun 2005 21:52:06 -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
@@ -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
diff --git a/drivers/i2c/chips/Makefile b/drivers/i2c/chips/Makefile
--- a/drivers/i2c/chips/Makefile
+++ b/drivers/i2c/chips/Makefile
@@ -14,6 +14,7 @@ obj-$(CONFIG_SENSORS_ADM1031) += adm1031
obj-$(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
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@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");
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 */