rtc: add support for spi rtc rx4581

[akpm@linux-foundation.org: checkpatch fixes]
Signed-off-by: Torben Hohn <torbenh@linutronix.de>
Cc: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

3 files changed, 323 insertions, 0 deletions

diff --git a/drivers/rtc/Kconfig b/drivers/rtc/Kconfig
index d52183440691..2e340763ba47 100644
--- a/drivers/rtc/Kconfig
+++ b/drivers/rtc/Kconfig
@@ -561,6 +561,14 @@ config RTC_DRV_PCF2123
           This driver can also be built as a module. If so, the module
           will be called rtc-pcf2123.
 
+config RTC_DRV_RX4581
+        tristate "Epson RX-4581"
+        help
+          If you say yes here you will get support for the Epson RX-4581.
+
+          This driver can also be built as a module. If so the module
+          will be called rtc-rx4581.
+
 endif # SPI_MASTER
 
 comment "Platform RTC drivers"
diff --git a/drivers/rtc/Makefile b/drivers/rtc/Makefile
index cd03fb33c14c..afd284d33714 100644
--- a/drivers/rtc/Makefile
+++ b/drivers/rtc/Makefile
@@ -98,6 +98,7 @@ obj-$(CONFIG_RTC_DRV_RS5C313)	+= rtc-rs5c313.o
 obj-$(CONFIG_RTC_DRV_RS5C348)   += rtc-rs5c348.o
 obj-$(CONFIG_RTC_DRV_RS5C372)   += rtc-rs5c372.o
 obj-$(CONFIG_RTC_DRV_RV3029C2)  += rtc-rv3029c2.o
+obj-$(CONFIG_RTC_DRV_RX4581)    += rtc-rx4581.o
 obj-$(CONFIG_RTC_DRV_RX8025)    += rtc-rx8025.o
 obj-$(CONFIG_RTC_DRV_RX8581)    += rtc-rx8581.o
 obj-$(CONFIG_RTC_DRV_S35390A)   += rtc-s35390a.o
diff --git a/drivers/rtc/rtc-rx4581.c b/drivers/rtc/rtc-rx4581.c
new file mode 100644
index 000000000000..599ec73ec886
--- /dev/null
+++ b/drivers/rtc/rtc-rx4581.c
@@ -0,0 +1,314 @@
+/* drivers/rtc/rtc-rx4581.c
+ *
+ * written by Torben Hohn <torbenh@linutronix.de>
+ *
+ * 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.
+ *
+ * Driver for MAX6902 spi RTC
+ *
+ * and based on:
+ * drivers/rtc/rtc-rx8581.c
+ *
+ * An I2C driver for the Epson RX8581 RTC
+ *
+ * Author: Martyn Welch <martyn.welch@ge.com>
+ * Copyright 2008 GE Intelligent Platforms Embedded Systems, Inc.
+ *
+ * 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.
+ *
+ * Based on: rtc-pcf8563.c (An I2C driver for the Philips PCF8563 RTC)
+ * Copyright 2005-06 Tower Technologies
+ *
+ */
+
+#include <linux/module.h>
+#include <linux/kernel.h>
+#include <linux/platform_device.h>
+#include <linux/init.h>
+#include <linux/rtc.h>
+#include <linux/spi/spi.h>
+#include <linux/bcd.h>
+
+#define RX4581_REG_SC           0x00 /* Second in BCD */
+#define RX4581_REG_MN           0x01 /* Minute in BCD */
+#define RX4581_REG_HR           0x02 /* Hour in BCD */
+#define RX4581_REG_DW           0x03 /* Day of Week */
+#define RX4581_REG_DM           0x04 /* Day of Month in BCD */
+#define RX4581_REG_MO           0x05 /* Month in BCD */
+#define RX4581_REG_YR           0x06 /* Year in BCD */
+#define RX4581_REG_RAM          0x07 /* RAM */
+#define RX4581_REG_AMN          0x08 /* Alarm Min in BCD*/
+#define RX4581_REG_AHR          0x09 /* Alarm Hour in BCD */
+#define RX4581_REG_ADM          0x0A
+#define RX4581_REG_ADW          0x0A
+#define RX4581_REG_TMR0         0x0B
+#define RX4581_REG_TMR1         0x0C
+#define RX4581_REG_EXT          0x0D /* Extension Register */
+#define RX4581_REG_FLAG         0x0E /* Flag Register */
+#define RX4581_REG_CTRL         0x0F /* Control Register */
+
+
+/* Flag Register bit definitions */
+#define RX4581_FLAG_UF          0x20 /* Update */
+#define RX4581_FLAG_TF          0x10 /* Timer */
+#define RX4581_FLAG_AF          0x08 /* Alarm */
+#define RX4581_FLAG_VLF         0x02 /* Voltage Low */
+
+/* Control Register bit definitions */
+#define RX4581_CTRL_UIE         0x20 /* Update Interrupt Enable */
+#define RX4581_CTRL_TIE         0x10 /* Timer Interrupt Enable */
+#define RX4581_CTRL_AIE         0x08 /* Alarm Interrupt Enable */
+#define RX4581_CTRL_STOP        0x02 /* STOP bit */
+#define RX4581_CTRL_RESET       0x01 /* RESET bit */
+
+static int rx4581_set_reg(struct device *dev, unsigned char address,
+                                unsigned char data)
+{
+        struct spi_device *spi = to_spi_device(dev);
+        unsigned char buf[2];
+
+        /* high nibble must be '0' to write */
+        buf[0] = address & 0x0f;
+        buf[1] = data;
+
+        return spi_write_then_read(spi, buf, 2, NULL, 0);
+}
+
+static int rx4581_get_reg(struct device *dev, unsigned char address,
+                                unsigned char *data)
+{
+        struct spi_device *spi = to_spi_device(dev);
+
+        /* Set MSB to indicate read */
+        *data = address | 0x80;
+
+        return spi_write_then_read(spi, data, 1, data, 1);
+}
+
+/*
+ * In the routines that deal directly with the rx8581 hardware, we use
+ * rtc_time -- month 0-11, hour 0-23, yr = calendar year-epoch.
+ */
+static int rx4581_get_datetime(struct device *dev, struct rtc_time *tm)
+{
+        struct spi_device *spi = to_spi_device(dev);
+        unsigned char date[7];
+        unsigned char data;
+        int err;
+
+        /* First we ensure that the "update flag" is not set, we read the
+         * time and date then re-read the "update flag". If the update flag
+         * has been set, we know that the time has changed during the read so
+         * we repeat the whole process again.
+         */
+        err = rx4581_get_reg(dev, RX4581_REG_FLAG, &data);
+        if (err != 0) {
+                dev_err(dev, "Unable to read device flags\n");
+                return -EIO;
+        }
+
+        do {
+                /* If update flag set, clear it */
+                if (data & RX4581_FLAG_UF) {
+                        err = rx4581_set_reg(dev,
+                                RX4581_REG_FLAG, (data & ~RX4581_FLAG_UF));
+                        if (err != 0) {
+                                dev_err(dev, "Unable to write device "
+                                        "flags\n");
+                                return -EIO;
+                        }
+                }
+
+                /* Now read time and date */
+                date[0] = 0x80;
+                err = spi_write_then_read(spi, date, 1, date, 7);
+                if (err < 0) {
+                        dev_err(dev, "Unable to read date\n");
+                        return -EIO;
+                }
+
+                /* Check flag register */
+                err = rx4581_get_reg(dev, RX4581_REG_FLAG, &data);
+                if (err != 0) {
+                        dev_err(dev, "Unable to read device flags\n");
+                        return -EIO;
+                }
+        } while (data & RX4581_FLAG_UF);
+
+        if (data & RX4581_FLAG_VLF)
+                dev_info(dev,
+                        "low voltage detected, date/time is not reliable.\n");
+
+        dev_dbg(dev,
+                "%s: raw data is sec=%02x, min=%02x, hr=%02x, "
+                "wday=%02x, mday=%02x, mon=%02x, year=%02x\n",
+                __func__,
+                date[0], date[1], date[2], date[3], date[4], date[5], date[6]);
+
+        tm->tm_sec = bcd2bin(date[RX4581_REG_SC] & 0x7F);
+        tm->tm_min = bcd2bin(date[RX4581_REG_MN] & 0x7F);
+        tm->tm_hour = bcd2bin(date[RX4581_REG_HR] & 0x3F); /* rtc hr 0-23 */