rtc: add support for maxim dallas rtc ds1347

Add support for maxim dallas rtc ds1347

Signed-off-by: Raghavendra Chandra Ganiga <ravi23ganiga@gmail.com>
Acked-by: Alessandro Zummo <a.zummo@towertech.it>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/drivers/rtc/Kconfig b/drivers/rtc/Kconfig
index db933decc39ce39ec26d9df0da4212d61fe3635d..2e565f8e5165018c8395d8e690fa0c57ee576b66 100644 (file)
--- a/drivers/rtc/Kconfig
+++ b/drivers/rtc/Kconfig
@@ -573,6 +573,18 @@ config RTC_DRV_DS1305
          This driver can also be built as a module. If so, the module
          will be called rtc-ds1305.
 
+config RTC_DRV_DS1347
+       tristate "Dallas/Maxim DS1347"
+       help
+         If you say yes here you get support for the
+         Dallas/Maxim DS1347 chips.
+
+         This driver only supports the RTC feature, and not other chip
+         features such as alarms.
+
+         This driver can also be built as a module. If so, the module
+         will be called rtc-ds1347.
+
 config RTC_DRV_DS1390
        tristate "Dallas/Maxim DS1390/93/94"
        help

diff --git a/drivers/rtc/Makefile b/drivers/rtc/Makefile
index b427bf7dd20d9330b83c14bbc47caa7f4b5e741f..40a09915c8f65464752392ae30ef34af329bdab8 100644 (file)
--- a/drivers/rtc/Makefile
+++ b/drivers/rtc/Makefile
@@ -40,6 +40,7 @@ obj-$(CONFIG_RTC_DRV_DS1286)  += rtc-ds1286.o
 obj-$(CONFIG_RTC_DRV_DS1302)   += rtc-ds1302.o
 obj-$(CONFIG_RTC_DRV_DS1305)   += rtc-ds1305.o
 obj-$(CONFIG_RTC_DRV_DS1307)   += rtc-ds1307.o
+obj-$(CONFIG_RTC_DRV_DS1347)   += rtc-ds1347.o
 obj-$(CONFIG_RTC_DRV_DS1374)   += rtc-ds1374.o
 obj-$(CONFIG_RTC_DRV_DS1390)   += rtc-ds1390.o
 obj-$(CONFIG_RTC_DRV_DS1511)   += rtc-ds1511.o

diff --git a/drivers/rtc/rtc-ds1347.c b/drivers/rtc/rtc-ds1347.c
new file mode 100644 (file)
index 0000000..c82b4c0
--- /dev/null
+++ b/drivers/rtc/rtc-ds1347.c
@@ -0,0 +1,166 @@
+/* rtc-ds1347.c
+ *
+ * Driver for Dallas Semiconductor DS1347 Low Current, SPI Compatible
+ * Real Time Clock
+ *
+ * Author : Raghavendra Chandra Ganiga <ravi23ganiga@gmail.com>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ *
+ */
+
+#include <linux/init.h>
+#include <linux/module.h>
+#include <linux/device.h>
+#include <linux/platform_device.h>
+#include <linux/rtc.h>
+#include <linux/spi/spi.h>
+#include <linux/bcd.h>
+
+/* Registers in ds1347 rtc */
+
+#define DS1347_SECONDS_REG     0x01
+#define DS1347_MINUTES_REG     0x03
+#define DS1347_HOURS_REG       0x05
+#define DS1347_DATE_REG                0x07
+#define DS1347_MONTH_REG       0x09
+#define DS1347_DAY_REG         0x0B
+#define DS1347_YEAR_REG                0x0D
+#define DS1347_CONTROL_REG     0x0F
+#define DS1347_STATUS_REG      0x17
+#define DS1347_CLOCK_BURST     0x3F
+
+static int ds1347_read_reg(struct device *dev, unsigned char address,
+                               unsigned char *data)
+{
+       struct spi_device *spi = to_spi_device(dev);
+
+       *data = address | 0x80;
+
+       return spi_write_then_read(spi, data, 1, data, 1);
+}
+
+static int ds1347_write_reg(struct device *dev, unsigned char address,
+                               unsigned char data)
+{
+       struct spi_device *spi = to_spi_device(dev);
+       unsigned char buf[2];
+
+       buf[0] = address & 0x7F;
+       buf[1] = data;
+
+       return spi_write_then_read(spi, buf, 2, NULL, 0);
+}
+
+static int ds1347_read_time(struct device *dev, struct rtc_time *dt)
+{
+       struct spi_device *spi = to_spi_device(dev);
+       int err;
+       unsigned char buf[8];
+
+       buf[0] = DS1347_CLOCK_BURST | 0x80;
+
+       err = spi_write_then_read(spi, buf, 1, buf, 8);
+       if (err)
+               return err;
+
+       dt->tm_sec = bcd2bin(buf[0]);
+       dt->tm_min = bcd2bin(buf[1]);
+       dt->tm_hour = bcd2bin(buf[2] & 0x3F);
+       dt->tm_mday = bcd2bin(buf[3]);
+       dt->tm_mon = bcd2bin(buf[4]) - 1;
+       dt->tm_wday = bcd2bin(buf[5]) - 1;
+       dt->tm_year = bcd2bin(buf[6]) + 100;
+
+       return rtc_valid_tm(dt);
+}
+
+static int ds1347_set_time(struct device *dev, struct rtc_time *dt)
+{
+       struct spi_device *spi = to_spi_device(dev);
+       unsigned char buf[9];
+
+       buf[0] = DS1347_CLOCK_BURST & 0x7F;
+       buf[1] = bin2bcd(dt->tm_sec);
+       buf[2] = bin2bcd(dt->tm_min);
+       buf[3] = (bin2bcd(dt->tm_hour) & 0x3F);
+       buf[4] = bin2bcd(dt->tm_mday);
+       buf[5] = bin2bcd(dt->tm_mon + 1);
+       buf[6] = bin2bcd(dt->tm_wday + 1);
+
+       /* year in linux is from 1900 i.e in range of 100
+       in rtc it is from 00 to 99 */
+       dt->tm_year = dt->tm_year % 100;
+
+       buf[7] = bin2bcd(dt->tm_year);
+       buf[8] = bin2bcd(0x00);
+
+       /* write the rtc settings */
+       return spi_write_then_read(spi, buf, 9, NULL, 0);
+}
+
+static const struct rtc_class_ops ds1347_rtc_ops = {
+       .read_time = ds1347_read_time,
+       .set_time = ds1347_set_time,
+};
+
+static int ds1347_probe(struct spi_device *spi)
+{
+       struct rtc_device *rtc;
+       unsigned char data;
+       int res;
+
+       /* spi setup with ds1347 in mode 3 and bits per word as 8 */
+       spi->mode = SPI_MODE_3;
+       spi->bits_per_word = 8;
+       spi_setup(spi);
+
+       /* RTC Settings */
+       res = ds1347_read_reg(&spi->dev, DS1347_SECONDS_REG, &data);
+       if (res)
+               return res;
+
+       /* Disable the write protect of rtc */
+       ds1347_read_reg(&spi->dev, DS1347_CONTROL_REG, &data);
+       data = data & ~(1<<7);
+       ds1347_write_reg(&spi->dev, DS1347_CONTROL_REG, data);
+
+       /* Enable the oscillator , disable the oscillator stop flag,
+        and glitch filter to reduce current consumption */
+       ds1347_read_reg(&spi->dev, DS1347_STATUS_REG, &data);
+       data = data & 0x1B;
+       ds1347_write_reg(&spi->dev, DS1347_STATUS_REG, data);
+
+       /* display the settings */
+       ds1347_read_reg(&spi->dev, DS1347_CONTROL_REG, &data);
+       dev_info(&spi->dev, "DS1347 RTC CTRL Reg = 0x%02x\n", data);
+
+       ds1347_read_reg(&spi->dev, DS1347_STATUS_REG, &data);
+       dev_info(&spi->dev, "DS1347 RTC Status Reg = 0x%02x\n", data);
+
+       rtc = devm_rtc_device_register(&spi->dev, "ds1347",
+                               &ds1347_rtc_ops, THIS_MODULE);
+
+       if (IS_ERR(rtc))
+               return PTR_ERR(rtc);
+
+       spi_set_drvdata(spi, rtc);
+
+       return 0;
+}
+
+static struct spi_driver ds1347_driver = {
+       .driver = {
+               .name = "ds1347",
+               .owner = THIS_MODULE,
+       },
+       .probe = ds1347_probe,
+};
+
+module_spi_driver(ds1347_driver);
+
+MODULE_DESCRIPTION("DS1347 SPI RTC DRIVER");
+MODULE_AUTHOR("Raghavendra C Ganiga <ravi23ganiga@gmail.com>");
+MODULE_LICENSE("GPL v2");