rtc: add MAX8907 RTC driver

The MAX8907 is an I2C-based power-management IC containing voltage
regulators, a reset controller, a real-time clock, and a touch-screen
controller.

The driver is based on an original by or fixed by:
* Tom Cherry
* Prashant Gaikwad
* Joseph Yoon

During upstreaming, I (swarren):
* Converted to regmap.
* Fixed handling of RTC_HOUR register containing 12.
* Fixed handling of RTC_WEEKDAY register.
* General cleanup.

Signed-off-by: Stephen Warren <swarren@nvidia.com>
Cc: Tom Cherry <tcherry@nvidia.com>
Cc: Prashant Gaikwad <pgaikwad@nvidia.com>
Cc: Joseph Yoon <tyoon@nvidia.com>
Cc: Alessandro Zummo <a.zummo@towertech.it>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

3 files changed, 255 insertions, 0 deletions

diff --git a/drivers/rtc/Kconfig b/drivers/rtc/Kconfig
index 6309df4e2654..499fb9984abe 100644
--- a/drivers/rtc/Kconfig
+++ b/drivers/rtc/Kconfig
@@ -205,6 +205,16 @@ config RTC_DRV_MAX6900
           This driver can also be built as a module. If so, the module
           will be called rtc-max6900.
 
+config RTC_DRV_MAX8907
+        tristate "Maxim MAX8907"
+        depends on MFD_MAX8907
+        help
+          If you say yes here you will get support for the
+          RTC of Maxim MAX8907 PMIC.
+
+          This driver can also be built as a module. If so, the module
+          will be called rtc-max8907.
+
 config RTC_DRV_MAX8925
         tristate "Maxim MAX8925"
         depends on MFD_MAX8925
diff --git a/drivers/rtc/Makefile b/drivers/rtc/Makefile
index 5c8f106237da..d9526b549f87 100644
--- a/drivers/rtc/Makefile
+++ b/drivers/rtc/Makefile
@@ -65,6 +65,7 @@ obj-$(CONFIG_RTC_DRV_M48T59)	+= rtc-m48t59.o
 obj-$(CONFIG_RTC_DRV_M48T86)    += rtc-m48t86.o
 obj-$(CONFIG_RTC_DRV_MXC)       += rtc-mxc.o
 obj-$(CONFIG_RTC_DRV_MAX6900)   += rtc-max6900.o
+obj-$(CONFIG_RTC_DRV_MAX8907)   += rtc-max8907.o
 obj-$(CONFIG_RTC_DRV_MAX8925)   += rtc-max8925.o
 obj-$(CONFIG_RTC_DRV_MAX8998)   += rtc-max8998.o
 obj-$(CONFIG_RTC_DRV_MAX6902)   += rtc-max6902.o
diff --git a/drivers/rtc/rtc-max8907.c b/drivers/rtc/rtc-max8907.c
new file mode 100644
index 000000000000..e094ffa434f8
--- /dev/null
+++ b/drivers/rtc/rtc-max8907.c
@@ -0,0 +1,244 @@
+/*
+ * RTC driver for Maxim MAX8907
+ *
+ * Copyright (c) 2011-2012, NVIDIA Corporation.
+ *
+ * Based on drivers/rtc/rtc-max8925.c,
+ * Copyright (C) 2009-2010 Marvell International 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/bcd.h>
+#include <linux/i2c.h>
+#include <linux/mfd/max8907.h>
+#include <linux/module.h>
+#include <linux/platform_device.h>
+#include <linux/regmap.h>
+#include <linux/rtc.h>
+#include <linux/slab.h>
+
+enum {
+        RTC_SEC = 0,
+        RTC_MIN,
+        RTC_HOUR,
+        RTC_WEEKDAY,
+        RTC_DATE,
+        RTC_MONTH,
+        RTC_YEAR1,
+        RTC_YEAR2,
+};
+
+#define TIME_NUM                        8
+#define ALARM_1SEC                      (1 << 7)
+#define HOUR_12                         (1 << 7)
+#define HOUR_AM_PM                      (1 << 5)
+#define ALARM0_IRQ                      (1 << 3)
+#define ALARM1_IRQ                      (1 << 2)
+#define ALARM0_STATUS                   (1 << 2)
+#define ALARM1_STATUS                   (1 << 1)
+
+struct max8907_rtc {
+        struct max8907          *max8907;
+        struct regmap           *regmap;
+        struct rtc_device       *rtc_dev;
+        int                     irq;
+};
+
+static irqreturn_t max8907_irq_handler(int irq, void *data)
+{
+        struct max8907_rtc *rtc = data;
+
+        regmap_update_bits(rtc->regmap, MAX8907_REG_ALARM0_CNTL, 0x7f, 0);
+
+        rtc_update_irq(rtc->rtc_dev, 1, RTC_IRQF | RTC_AF);
+
+        return IRQ_HANDLED;
+}
+
+static void regs_to_tm(u8 *regs, struct rtc_time *tm)
+{
+        tm->tm_year = bcd2bin(regs[RTC_YEAR2]) * 100 +
+                bcd2bin(regs[RTC_YEAR1]) - 1900;
+        tm->tm_mon = bcd2bin(regs[RTC_MONTH] & 0x1f) - 1;
+        tm->tm_mday = bcd2bin(regs[RTC_DATE] & 0x3f);
+        tm->tm_wday = (regs[RTC_WEEKDAY] & 0x07) - 1;
+        if (regs[RTC_HOUR] & HOUR_12) {
+                tm->tm_hour = bcd2bin(regs[RTC_HOUR] & 0x01f);
+                if (tm->tm_hour == 12)
+                        tm->tm_hour = 0;
+                if (regs[RTC_HOUR] & HOUR_AM_PM)
+                        tm->tm_hour += 12;
+        } else {
+                tm->tm_hour = bcd2bin(regs[RTC_HOUR] & 0x03f);
+        }
+        tm->tm_min = bcd2bin(regs[RTC_MIN] & 0x7f);
+        tm->tm_sec = bcd2bin(regs[RTC_SEC] & 0x7f);
+}
+
+static void tm_to_regs(struct rtc_time *tm, u8 *regs)
+{
+        u8 high, low;
+
+        high = (tm->tm_year + 1900) / 100;
+        low = tm->tm_year % 100;
+        regs[RTC_YEAR2] = bin2bcd(high);
+        regs[RTC_YEAR1] = bin2bcd(low);
+        regs[RTC_MONTH] = bin2bcd(tm->tm_mon + 1);
+        regs[RTC_DATE] = bin2bcd(tm->tm_mday);
+        regs[RTC_WEEKDAY] = tm->tm_wday + 1;
+        regs[RTC_HOUR] = bin2bcd(tm->tm_hour);
+        regs[RTC_MIN] = bin2bcd(tm->tm_min);
+        regs[RTC_SEC] = bin2bcd(tm->tm_sec);
+}
+
+static int max8907_rtc_read_time(struct device *dev, struct rtc_time *tm)
+{
+        struct max8907_rtc *rtc = dev_get_drvdata(dev);
+        u8 regs[TIME_NUM];
+        int ret;
+
+        ret = regmap_bulk_read(rtc->regmap, MAX8907_REG_RTC_SEC, regs,
+                               TIME_NUM);
+        if (ret < 0)
+                return ret;
+
+        regs_to_tm(regs, tm);
+
+        return 0;
+}
+
+static int max8907_rtc_set_time(struct device *dev, struct rtc_time *tm)
+{
+        struct max8907_rtc *rtc = dev_get_drvdata(dev);
+        u8 regs[TIME_NUM];
+
+        tm_to_regs(tm, regs);
+
+        return regmap_bulk_write(rtc->regmap, MAX8907_REG_RTC_SEC, regs,
+                                 TIME_NUM);
+}
+
+static int max8907_rtc_read_alarm(struct device *dev, struct rtc_wkalrm *alrm)
+{
+        struct max8907_rtc *rtc = dev_get_drvdata(dev);
+        u8 regs[TIME_NUM];
+        unsigned int val;
+        int ret;
+
+        ret = regmap_bulk_read(rtc->regmap, MAX8907_REG_ALARM0_SEC, regs,
+                               TIME_NUM);
+        if (ret < 0)
+                return ret;
+
+        regs_to_tm(regs, &alrm->time);
+
+        ret = regmap_read(rtc->regmap, MAX8907_REG_ALARM0_CNTL, &val);
+        if (ret < 0)
+                return ret;
+
+        alrm->enabled = !!(val & 0x7f);
+
+        return 0;
+}
+
+static int max8907_rtc_set_alarm(struct device *dev, struct rtc_wkalrm *alrm)
+{
+        struct max8907_rtc *rtc = dev_get_drvdata(dev);
+        u8 regs[TIME_NUM];
+        int ret;
+
+        tm_to_regs(&alrm->time, regs);
+
+        /* Disable alarm while we update the target time */
+        ret = regmap_update_bits(rtc->regmap, MAX8907_REG_ALARM0_CNTL, 0x7f, 0);
+        if (ret < 0)
+                return ret;
+
+        ret = regmap_bulk_write(rtc->regmap, MAX8907_REG_ALARM0_SEC, regs,
+                                TIME_NUM);
+        if (ret < 0)
+                return ret;
+
+        if (alrm->enabled)
+                ret = regmap_update_bits(rtc->regmap, MAX8907_REG_ALARM0_CNTL,
+                                         0x7f, 0x7f);
+
+        return ret;
+}
+
+static const struct rtc_class_ops max8907_rtc_ops = {
+        .read_time      = max8907_rtc_read_time,
+        .set_time       = max8907_rtc_set_time,
+        .read_alarm     = max8907_rtc_read_alarm,
+        .set_alarm      = max8907_rtc_set_alarm,
+};
+
+static int __devinit max8907_rtc_probe(struct platform_device *pdev)
+{
+        struct max8907 *max8907 = dev_get_drvdata(pdev->dev.parent);
+        struct max8907_rtc *rtc;
+        int ret;
+
+        rtc = devm_kzalloc(&pdev->dev, sizeof(*rtc), GFP_KERNEL);
+        if (!rtc)
+                return -ENOMEM;
+        platform_set_drvdata(pdev, rtc);
+
+        rtc->max8907 = max8907;
+        rtc->regmap = max8907->regmap_rtc;
+
+        rtc->rtc_dev = rtc_device_register("max8907-rtc", &pdev->dev,
+                                        &max8907_rtc_ops, THIS_MODULE);
+        if (IS_ERR(rtc->rtc_dev)) {
+                ret = PTR_ERR(rtc->rtc_dev);
+                dev_err(&pdev->dev, "Failed to register RTC device: %d\n", ret);
+                return ret;
+        }
+
+        rtc->irq = regmap_irq_get_virq(max8907->irqc_rtc,
+                                       MAX8907_IRQ_RTC_ALARM0);
+        if (rtc->irq < 0) {
+                ret = rtc->irq;
+                goto err_unregister;
+        }
+
+        ret = request_threaded_irq(rtc->irq, NULL, max8907_irq_handler,
+                                   IRQF_ONESHOT, "max8907-alarm0", rtc);
+        if (ret < 0) {
+                dev_err(&pdev->dev, "Failed to request IRQ%d: %d\n",
+                        rtc->irq, ret);
+                goto err_unregister;
+        }
+
+        return 0;
+
+err_unregister:
+        rtc_device_unregister(rtc->rtc_dev);
+        return ret;
+}
+
+static int __devexit max8907_rtc_remove(struct platform_device *pdev)
+{
+        struct max8907_rtc *rtc = platform_get_drvdata(pdev);
+
+        free_irq(rtc->irq, rtc);
+        rtc_device_unregister(rtc->rtc_dev);
+
+        return 0;
+}
+
+static struct platform_driver max8907_rtc_driver = {
+        .driver = {
+                .name = "max8907-rtc",
+                .owner = THIS_MODULE,
+        },
+        .probe = max8907_rtc_probe,
+        .remove = __devexit_p(max8907_rtc_remove),
+};
+module_platform_driver(max8907_rtc_driver);
+
+MODULE_DESCRIPTION("Maxim MAX8907 RTC driver");
+MODULE_LICENSE("GPL v2");