rtc: add Dallas DS1390/93/94 RTC chips

Add support for the Dallas DS1390/93/94 SPI RTC chip.

Signed-off-by: Mark Jackson <mpfj@mimc.co.uk>
Acked-by: Alessandro Zummo <a.zummo@towertech.it>
Cc: David Brownell <david-b@pacbell.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

3 files changed, 232 insertions, 0 deletions

diff --git a/drivers/rtc/Kconfig b/drivers/rtc/Kconfig
index 990020c1dae9..123092d8a984 100644
--- a/drivers/rtc/Kconfig
+++ b/drivers/rtc/Kconfig
@@ -310,6 +310,17 @@ 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_DS1390
+        tristate "Dallas/Maxim DS1390/93/94"
+        help
+          If you say yes here you get support for the DS1390/93/94 chips.
+
+          This driver only supports the RTC feature, and not other chip
+          features such as alarms and trickle charging.
+
+          This driver can also be built as a module. If so, the module
+          will be called rtc-ds1390.
+
 config RTC_DRV_MAX6902
         tristate "Maxim MAX6902"
         help
diff --git a/drivers/rtc/Makefile b/drivers/rtc/Makefile
index 16368600643c..6e79c912bf9e 100644
--- a/drivers/rtc/Makefile
+++ b/drivers/rtc/Makefile
@@ -28,6 +28,7 @@ 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_DS1374)    += rtc-ds1374.o
+obj-$(CONFIG_RTC_DRV_DS1390)    += rtc-ds1390.o
 obj-$(CONFIG_RTC_DRV_DS1511)    += rtc-ds1511.o
 obj-$(CONFIG_RTC_DRV_DS1553)    += rtc-ds1553.o
 obj-$(CONFIG_RTC_DRV_DS1672)    += rtc-ds1672.o
diff --git a/drivers/rtc/rtc-ds1390.c b/drivers/rtc/rtc-ds1390.c
new file mode 100644
index 000000000000..599e976bf014
--- /dev/null
+++ b/drivers/rtc/rtc-ds1390.c
@@ -0,0 +1,220 @@
+/*
+ * rtc-ds1390.c -- driver for DS1390/93/94
+ *
+ * Copyright (C) 2008 Mercury IMC Ltd
+ * Written by Mark Jackson <mpfj@mimc.co.uk>
+ *
+ * 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.
+ *
+ * NOTE : Currently this driver only supports the bare minimum for read
+ * and write the RTC.  The extra features provided by the chip family
+ * (alarms, trickle charger, different control registers) are unavailable.
+ */
+
+#include <linux/platform_device.h>
+#include <linux/rtc.h>
+#include <linux/spi/spi.h>
+#include <linux/bcd.h>
+
+#define DS1390_REG_100THS               0x00
+#define DS1390_REG_SECONDS              0x01
+#define DS1390_REG_MINUTES              0x02
+#define DS1390_REG_HOURS                0x03
+#define DS1390_REG_DAY                  0x04
+#define DS1390_REG_DATE                 0x05
+#define DS1390_REG_MONTH_CENT           0x06
+#define DS1390_REG_YEAR                 0x07
+
+#define DS1390_REG_ALARM_100THS         0x08
+#define DS1390_REG_ALARM_SECONDS        0x09
+#define DS1390_REG_ALARM_MINUTES        0x0A
+#define DS1390_REG_ALARM_HOURS          0x0B
+#define DS1390_REG_ALARM_DAY_DATE       0x0C
+
+#define DS1390_REG_CONTROL              0x0D
+#define DS1390_REG_STATUS               0x0E
+#define DS1390_REG_TRICKLE              0x0F
+
+struct ds1390 {
+        struct rtc_device *rtc;
+        u8 txrx_buf[9]; /* cmd + 8 registers */
+};
+
+static void ds1390_set_reg(struct device *dev, unsigned char address,
+                                unsigned char data)
+{
+        struct spi_device *spi = to_spi_device(dev);
+        struct ds1390 *chip = dev_get_drvdata(dev);
+
+        /* Set MSB to indicate write */
+        chip->txrx_buf[0] = address | 0x80;
+        chip->txrx_buf[1] = data;
+
+        /* do the i/o */
+        spi_write_then_read(spi, chip->txrx_buf, 2, NULL, 0);
+}
+
+static int ds1390_get_reg(struct device *dev, unsigned char address,
+                                unsigned char *data)
+{
+        struct spi_device *spi = to_spi_device(dev);
+        struct ds1390 *chip = dev_get_drvdata(dev);
+        int status;
+
+        if (!data)
+                return -EINVAL;
+
+        /* Clear MSB to indicate read */
+        chip->txrx_buf[0] = address & 0x7f;
+        /* do the i/o */
+        status = spi_write_then_read(spi, chip->txrx_buf, 1, chip->txrx_buf, 1);
+        if (status != 0)
+                return status;
+
+        *data = chip->txrx_buf[1];
+
+        return 0;
+}
+
+static int ds1390_get_datetime(struct device *dev, struct rtc_time *dt)
+{
+        struct spi_device *spi = to_spi_device(dev);
+        struct ds1390 *chip = dev_get_drvdata(dev);
+        int status;
+
+        /* build the message */
+        chip->txrx_buf[0] = DS1390_REG_SECONDS;
+
+        /* do the i/o */
+        status = spi_write_then_read(spi, chip->txrx_buf, 1, chip->txrx_buf, 8);
+        if (status != 0)
+                return status;
+
+        /* The chip sends data in this order:
+         * Seconds, Minutes, Hours, Day, Date, Month / Century, Year */
+        dt->tm_sec      = bcd2bin(chip->txrx_buf[0]);
+        dt->tm_min      = bcd2bin(chip->txrx_buf[1]);
+        dt->tm_hour     = bcd2bin(chip->txrx_buf[2]);
+        dt->tm_wday     = bcd2bin(chip->txrx_buf[3]);
+        dt->tm_mday     = bcd2bin(chip->txrx_buf[4]);
+        /* mask off century bit */
+        dt->tm_mon      = bcd2bin(chip->txrx_buf[5] & 0x7f) - 1;
+        /* adjust for century bit */
+        dt->tm_year = bcd2bin(chip->txrx_buf[6]) + ((chip->txrx_buf[5] & 0x80) ? 100 : 0);
+
+        return rtc_valid_tm(dt);
+}
+
+static int ds1390_set_datetime(struct device *dev, struct rtc_time *dt)
+{
+        struct spi_device *spi = to_spi_device(dev);
+        struct ds1390 *chip = dev_get_drvdata(dev);
+
+        /* build the message */
+        chip->txrx_buf[0] = DS1390_REG_SECONDS | 0x80;
+        chip->txrx_buf[1] = bin2bcd(dt->tm_sec);
+        chip->txrx_buf[2] = bin2bcd(dt->tm_min);
+        chip->txrx_buf[3] = bin2bcd(dt->tm_hour);
+        chip->txrx_buf[4] = bin2bcd(dt->tm_wday);
+        chip->txrx_buf[5] = bin2bcd(dt->tm_mday);
+        chip->txrx_buf[6] = bin2bcd(dt->tm_mon + 1) |
+                                ((dt->tm_year > 99) ? 0x80 : 0x00);
+        chip->txrx_buf[7] = bin2bcd(dt->tm_year % 100);
+
+        /* do the i/o */
+        return spi_write_then_read(spi, chip->txrx_buf, 8, NULL, 0);
+}
+
+static int ds1390_read_time(struct device *dev, struct rtc_time *tm)
+{
+        return ds1390_get_datetime(dev, tm);
+}
+
+static int ds1390_set_time(struct device *dev, struct rtc_time *tm)
+{
+        return ds1390_set_datetime(dev, tm);
+}
+
+static const struct rtc_class_ops ds1390_rtc_ops = {
+        .read_time      = ds1390_read_time,
+        .set_time       = ds1390_set_time,
+};
+
+static int __devinit ds1390_probe(struct spi_device *spi)
+{
+        struct rtc_device *rtc;
+        unsigned char tmp;
+        struct ds1390 *chip;
+        int res;
+
+        printk(KERN_DEBUG "DS1390 SPI RTC driver\n");
+
+        rtc = rtc_device_register("ds1390",
+                                &spi->dev, &ds1390_rtc_ops, THIS_MODULE);
+        if (IS_ERR(rtc)) {
+                printk(KERN_ALERT "RTC : unable to register device\n");
+                return PTR_ERR(rtc);
+        }
+
+        spi->mode = SPI_MODE_3;
+        spi->bits_per_word = 8;
+        spi_setup(spi);
+
+        chip = kzalloc(sizeof *chip, GFP_KERNEL);
+        if (!chip) {
+                printk(KERN_ALERT "RTC : unable to allocate device memory\n");
+                rtc_device_unregister(rtc);
+                return -ENOMEM;
+        }
+        chip->rtc = rtc;
+        dev_set_drvdata(&spi->dev, chip);
+
+        res = ds1390_get_reg(&spi->dev, DS1390_REG_SECONDS, &tmp);
+        if (res) {
+                printk(KERN_ALERT "RTC : unable to read device\n");
+                rtc_device_unregister(rtc);
+                return res;
+        }
+
+        return 0;
+}
+
+static int __devexit ds1390_remove(struct spi_device *spi)
+{
+        struct ds1390 *chip = platform_get_drvdata(spi);
+        struct rtc_device *rtc = chip->rtc;
+
+        if (rtc)
+                rtc_device_unregister(rtc);
+
+        kfree(chip);
+
+        return 0;
+}
+
+static struct spi_driver ds1390_driver = {
+        .driver = {
+                .name   = "rtc-ds1390",
+                .owner  = THIS_MODULE,
+        },
+        .probe  = ds1390_probe,
+        .remove = __devexit_p(ds1390_remove),
+};
+
+static __init int ds1390_init(void)
+{
+        return spi_register_driver(&ds1390_driver);
+}
+module_init(ds1390_init);
+
+static __exit void ds1390_exit(void)
+{
+        spi_unregister_driver(&ds1390_driver);
+}
+module_exit(ds1390_exit);
+
+MODULE_DESCRIPTION("DS1390/93/94 SPI RTC driver");
+MODULE_AUTHOR("Mark Jackson <mpfj@mimc.co.uk>");
+MODULE_LICENSE("GPL");