rtc: add support for Epson RTC-9701JE V2

Add support for the Epson RTC-9701JE SPI RTC device.

Signed-off-by: Magnus Damm <damm@igel.co.jp>
Acked-by: Alessandro Zummo <a.zummo@towertech.it>
Acked-by: 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, 205 insertions, 0 deletions

diff --git a/drivers/rtc/Kconfig b/drivers/rtc/Kconfig
index 4a39b76aeacd..484de8e4c5ae 100644
--- a/drivers/rtc/Kconfig
+++ b/drivers/rtc/Kconfig
@@ -265,6 +265,15 @@ config RTC_DRV_MAX6902
           This driver can also be built as a module. If so, the module
           will be called rtc-max6902.
 
+config RTC_DRV_R9701
+        tristate "Epson RTC-9701JE"
+        help
+          If you say yes here you will get support for the
+          Epson RTC-9701JE SPI RTC chip.
+
+          This driver can also be built as a module. If so, the module
+          will be called rtc-r9701.
+
 config RTC_DRV_RS5C348
         tristate "Ricoh RS5C348A/B"
         help
diff --git a/drivers/rtc/Makefile b/drivers/rtc/Makefile
index 36586c28cefc..81f7c9a05a4a 100644
--- a/drivers/rtc/Makefile
+++ b/drivers/rtc/Makefile
@@ -40,6 +40,7 @@ obj-$(CONFIG_RTC_DRV_OMAP)	+= rtc-omap.o
 obj-$(CONFIG_RTC_DRV_PCF8563)   += rtc-pcf8563.o
 obj-$(CONFIG_RTC_DRV_PCF8583)   += rtc-pcf8583.o
 obj-$(CONFIG_RTC_DRV_PL031)     += rtc-pl031.o
+obj-$(CONFIG_RTC_DRV_R9701)     += rtc-r9701.o
 obj-$(CONFIG_RTC_DRV_RS5C313)   += rtc-rs5c313.o
 obj-$(CONFIG_RTC_DRV_RS5C348)   += rtc-rs5c348.o
 obj-$(CONFIG_RTC_DRV_RS5C372)   += rtc-rs5c372.o
diff --git a/drivers/rtc/rtc-r9701.c b/drivers/rtc/rtc-r9701.c
new file mode 100644
index 000000000000..926e8fda83c0
--- /dev/null
+++ b/drivers/rtc/rtc-r9701.c
@@ -0,0 +1,195 @@
+/* drivers/rtc/rtc-r9701.c
+ *
+ * Driver for Epson RTC-9701JE
+ *
+ * Copyright (C) 2008 Magnus Damm
+ *
+ * Based on drivers/rtc/rtc-max6902.c
+ *
+ * Copyright (C) 2006 8D Technologies inc.
+ * Copyright (C) 2004 Compulab Ltd.
+ *
+ * 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/module.h>
+#include <linux/version.h>
+#include <linux/kernel.h>
+#include <linux/platform_device.h>
+#include <linux/device.h>
+#include <linux/init.h>
+#include <linux/rtc.h>
+#include <linux/spi/spi.h>
+#include <linux/bcd.h>
+#include <linux/delay.h>
+#include <linux/bitops.h>
+
+#define RSECCNT 0x00    /* Second Counter */
+#define RMINCNT 0x01    /* Minute Counter */
+#define RHRCNT  0x02    /* Hour Counter */
+#define RWKCNT  0x03    /* Week Counter */
+#define RDAYCNT 0x04    /* Day Counter */
+#define RMONCNT 0x05    /* Month Counter */
+#define RYRCNT  0x06    /* Year Counter */
+#define R100CNT 0x07    /* Y100 Counter */
+#define RMINAR  0x08    /* Minute Alarm */
+#define RHRAR   0x09    /* Hour Alarm */
+#define RWKAR   0x0a    /* Week/Day Alarm */
+#define RTIMCNT 0x0c    /* Interval Timer */
+#define REXT    0x0d    /* Extension Register */
+#define RFLAG   0x0e    /* RTC Flag Register */
+#define RCR     0x0f    /* RTC Control Register */
+
+static int write_reg(struct device *dev, int 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(spi, buf, ARRAY_SIZE(buf));
+}
+
+static int read_regs(struct device *dev, unsigned char *regs, int no_regs)
+{
+        struct spi_device *spi = to_spi_device(dev);
+        u8 txbuf[1], rxbuf[1];
+        int k, ret;
+
+        ret = 0;
+
+        for (k = 0; ret == 0 && k < no_regs; k++) {
+                txbuf[0] = 0x80 | regs[k];
+                ret = spi_write_then_read(spi, txbuf, 1, rxbuf, 1);
+                regs[k] = rxbuf[0];
+        }
+
+        return ret;
+}
+
+static int r9701_get_datetime(struct device *dev, struct rtc_time *dt)
+{
+        struct spi_device *spi = to_spi_device(dev);
+        unsigned long time;
+        int ret;
+        unsigned char buf[] = { RSECCNT, RMINCNT, RHRCNT,
+                                RDAYCNT, RMONCNT, RYRCNT };
+
+        ret = read_regs(&spi->dev, buf, ARRAY_SIZE(buf));
+        if (ret)
+                return ret;
+
+        memset(dt, 0, sizeof(*dt));
+
+        dt->tm_sec = BCD2BIN(buf[0]); /* RSECCNT */
+        dt->tm_min = BCD2BIN(buf[1]); /* RMINCNT */
+        dt->tm_hour = BCD2BIN(buf[2]); /* RHRCNT */
+
+        dt->tm_mday = BCD2BIN(buf[3]); /* RDAYCNT */
+        dt->tm_mon = BCD2BIN(buf[4]) - 1; /* RMONCNT */
+        dt->tm_year = BCD2BIN(buf[5]) + 100; /* RYRCNT */
+
+        /* the rtc device may contain illegal values on power up
+         * according to the data sheet. make sure they are valid.
+         */
+
+        ret = rtc_valid_tm(dt);
+        if (ret)
+                return ret;
+
+        /* don't bother with yday, wday and isdst.
+         * let the rtc core calculate them for us.
+         */
+
+        rtc_tm_to_time(dt, &time);
+        rtc_time_to_tm(time, dt);
+        return 0;
+}
+
+static int r9701_set_datetime(struct device *dev, struct rtc_time *dt)
+{
+        int ret, year;
+
+        year = dt->tm_year + 1900;
+        if (year >= 2100 || year < 2000)
+                return -EINVAL;
+
+        ret = write_reg(dev, RHRCNT, BIN2BCD(dt->tm_hour));
+        ret |= write_reg(dev, RMINCNT, BIN2BCD(dt->tm_min));
+        ret |= write_reg(dev, RSECCNT, BIN2BCD(dt->tm_sec));
+        ret |= write_reg(dev, RDAYCNT, BIN2BCD(dt->tm_mday));
+        ret |= write_reg(dev, RMONCNT, BIN2BCD(dt->tm_mon + 1));
+        ret |= write_reg(dev, RYRCNT, BIN2BCD(dt->tm_year - 100));
+        ret |= write_reg(dev, RWKCNT, 1 << dt->tm_wday);
+
+        return ret;
+}
+
+static const struct rtc_class_ops r9701_rtc_ops = {
+        .read_time      = r9701_get_datetime,
+        .set_time       = r9701_set_datetime,
+};
+
+static int __devinit r9701_probe(struct spi_device *spi)
+{
+        struct rtc_device *rtc;
+        unsigned char tmp;
+        int res;
+
+        rtc = rtc_device_register("r9701",
+                                &spi->dev, &r9701_rtc_ops, THIS_MODULE);
+        if (IS_ERR(rtc))
+                return PTR_ERR(rtc);
+
+        dev_set_drvdata(&spi->dev, rtc);
+
+        spi->mode = SPI_MODE_3;
+        spi->bits_per_word = 8;
+        spi_setup(spi);
+
+        tmp = R100CNT;
+        res = read_regs(&spi->dev, &tmp, 1);
+        if (res || tmp != 0x20) {
+                rtc_device_unregister(rtc);
+                return res;
+        }
+
+        return 0;
+}
+
+static int __devexit r9701_remove(struct spi_device *spi)
+{
+        struct rtc_device *rtc = dev_get_drvdata(&spi->dev);
+
+        rtc_device_unregister(rtc);
+        return 0;
+}
+
+static struct spi_driver r9701_driver = {
+        .driver = {
+                .name   = "rtc-r9701",
+                .bus    = &spi_bus_type,
+                .owner  = THIS_MODULE,
+        },
+        .probe  = r9701_probe,
+        .remove = __devexit_p(r9701_remove),
+};
+
+static __init int r9701_init(void)
+{
+        return spi_register_driver(&r9701_driver);
+}
+module_init(r9701_init);
+
+static __exit void r9701_exit(void)
+{
+        spi_unregister_driver(&r9701_driver);
+}
+module_exit(r9701_exit);
+
+MODULE_DESCRIPTION("r9701 spi RTC driver");
+MODULE_AUTHOR("Magnus Damm <damm@opensource.se>");
+MODULE_LICENSE("GPL");