rtc: add support for EPSON TOYOCOM RTC-7301SF/DG

diff --git a/Documentation/devicetree/bindings/rtc/epson,rtc7301.txt b/Documentation/devicetree/bindings/rtc/epson,rtc7301.txt
new file mode 100644
index 0000000..e1a94cb
--- /dev/null
+++ b/Documentation/devicetree/bindings/rtc/epson,rtc7301.txt
@@ -0,0 +1,15 @@ 
+EPSON TOYOCOM RTC-7301SF/DG
+
+Required properties:
+
+- compatible: Should be "epson,rtc7301sf" or "epson,rtc7301dg"
+- reg: Specifies base physical address and size of the registers.
+- interrupts: A single interrupt specifier.
+
+Example:
+
+rtc: rtc@44a00000 {
+	compatible = "epson,rtc7301dg";
+	reg = <0x44a00000 0x10000>;
+	interrupts = <2 2>;
+};
diff --git a/drivers/rtc/Kconfig b/drivers/rtc/Kconfig
index 618f644..9242c5e 100644
--- a/drivers/rtc/Kconfig
+++ b/drivers/rtc/Kconfig
@@ -1669,6 +1669,17 @@  config RTC_DRV_PIC32
 	   This driver can also be built as a module. If so, the module
 	   will be called rtc-pic32
 
+config RTC_DRV_R7301
+	tristate "EPSON TOYOCOM RTC-7301SF/DG"
+	select REGMAP_MMIO
+	depends on OF && HAS_IOMEM
+	help
+	   If you say yes here you get support for the EPSON TOYOCOM
+	   RTC-7301SF/DG chips.
+
+	   This driver can also be built as a module. If so, the module
+	   will be called rtc-r7301.
+
 comment "HID Sensor RTC drivers"
 
 config RTC_DRV_HID_SENSOR_TIME
diff --git a/drivers/rtc/Makefile b/drivers/rtc/Makefile
index ea28337..abab534 100644
--- a/drivers/rtc/Makefile
+++ b/drivers/rtc/Makefile
@@ -118,6 +118,7 @@  obj-$(CONFIG_RTC_DRV_PM8XXX)	+= rtc-pm8xxx.o
 obj-$(CONFIG_RTC_DRV_PS3)	+= rtc-ps3.o
 obj-$(CONFIG_RTC_DRV_PUV3)	+= rtc-puv3.o
 obj-$(CONFIG_RTC_DRV_PXA)	+= rtc-pxa.o
+obj-$(CONFIG_RTC_DRV_R7301)	+= rtc-r7301.o
 obj-$(CONFIG_RTC_DRV_R9701)	+= rtc-r9701.o
 obj-$(CONFIG_RTC_DRV_RC5T583)	+= rtc-rc5t583.o
 obj-$(CONFIG_RTC_DRV_RK808)	+= rtc-rk808.o
diff --git a/drivers/rtc/rtc-r7301.c b/drivers/rtc/rtc-r7301.c
new file mode 100644
index 0000000..b1be281
--- /dev/null
+++ b/drivers/rtc/rtc-r7301.c
@@ -0,0 +1,458 @@ 
+/*
+ * EPSON TOYOCOM RTC-7301SF/DG Driver
+ *
+ * Copyright (c) 2016 Akinobu Mita <akinobu.mita@gmail.com>
+ *
+ * Based on rtc-rp5c01.c
+ *
+ * Datasheet: http://www5.epsondevice.com/en/products/parallel/rtc7301sf.html
+ */
+
+#include <linux/io.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/delay.h>
+#include <linux/regmap.h>
+#include <linux/platform_device.h>
+#include <linux/rtc.h>
+
+#define DRV_NAME "rtc-r7301"
+
+enum {
+	RTC7301_1_SEC		= 0x0,	/* Bank 0 and Band 1 */
+	RTC7301_10_SEC		= 0x1,	/* Bank 0 and Band 1 */
+	RTC7301_AE		= BIT(3),
+	RTC7301_1_MIN		= 0x2,	/* Bank 0 and Band 1 */
+	RTC7301_10_MIN		= 0x3,	/* Bank 0 and Band 1 */
+	RTC7301_1_HOUR		= 0x4,	/* Bank 0 and Band 1 */
+	RTC7301_10_HOUR		= 0x5,	/* Bank 0 and Band 1 */
+	RTC7301_DAY_OF_WEEK	= 0x6,	/* Bank 0 and Band 1 */
+	RTC7301_1_DAY		= 0x7,	/* Bank 0 and Band 1 */
+	RTC7301_10_DAY		= 0x8,	/* Bank 0 and Band 1 */
+	RTC7301_1_MONTH		= 0x9,	/* Bank 0 */
+	RTC7301_10_MONTH	= 0xa,	/* Bank 0 */
+	RTC7301_1_YEAR		= 0xb,	/* Bank 0 */
+	RTC7301_10_YEAR		= 0xc,	/* Bank 0 */
+	RTC7301_100_YEAR	= 0xd,	/* Bank 0 */
+	RTC7301_1000_YEAR	= 0xe,	/* Bank 0 */
+	RTC7301_ALARM_CONTROL	= 0xe,	/* Bank 1 */
+	RTC7301_ALARM_CONTROL_AIE	= BIT(0),
+	RTC7301_ALARM_CONTROL_AF	= BIT(1),
+	RTC7301_TIMER_CONTROL	= 0xe,	/* Bank 2 */
+	RTC7301_ALARM_CONTROL_TIE	= BIT(0),
+	RTC7301_ALARM_CONTROL_TF	= BIT(1),
+	RTC7301_CONTROL		= 0xf,	/* All banks */
+	RTC7301_CONTROL_BUSY		= BIT(0),
+	RTC7301_CONTROL_STOP		= BIT(1),
+	RTC7301_CONTROL_BANK_SEL_0	= BIT(2),
+	RTC7301_CONTROL_BANK_SEL_1	= BIT(3),
+};
+
+struct rtc7301_priv {
+	struct regmap *regmap;
+	int irq;
+	spinlock_t lock;
+	u8 bank;
+};
+
+static const struct regmap_config rtc7301_regmap_config = {
+	.reg_bits = 32,
+	.val_bits = 8,
+	.reg_stride = 4,
+};
+
+static u8 rtc7301_read(struct rtc7301_priv *priv, unsigned int reg)
+{
+	int reg_stride = regmap_get_reg_stride(priv->regmap);
+	unsigned int val;
+
+	regmap_read(priv->regmap, reg_stride * reg, &val);
+
+	return val & 0xf;
+}
+
+static void rtc7301_write(struct rtc7301_priv *priv, u8 val, unsigned int reg)
+{
+	int reg_stride = regmap_get_reg_stride(priv->regmap);
+
+	regmap_write(priv->regmap, reg_stride * reg, val);
+}
+
+static void rtc7301_update_bits(struct rtc7301_priv *priv, unsigned int reg,
+				u8 mask, u8 val)
+{
+	int reg_stride = regmap_get_reg_stride(priv->regmap);
+
+	regmap_update_bits(priv->regmap, reg_stride * reg, mask, val);
+}
+
+static int rtc7301_wait_while_busy(struct rtc7301_priv *priv)
+{
+	int retries = 100;
+
+	while (retries-- > 0) {
+		u8 val;
+
+		val = rtc7301_read(priv, RTC7301_CONTROL);
+		if (!(val & RTC7301_CONTROL_BUSY))
+			return 0;
+
+		usleep_range(200, 300);
+	}
+
+	return -ETIMEDOUT;
+}
+
+static void rtc7301_stop(struct rtc7301_priv *priv)
+{
+	rtc7301_update_bits(priv, RTC7301_CONTROL, RTC7301_CONTROL_STOP,
+			    RTC7301_CONTROL_STOP);
+}
+
+static void rtc7301_start(struct rtc7301_priv *priv)
+{
+	rtc7301_update_bits(priv, RTC7301_CONTROL, RTC7301_CONTROL_STOP, 0);
+}
+
+static void rtc7301_select_bank(struct rtc7301_priv *priv, u8 bank)
+{
+	u8 val = 0;
+
+	if (bank == priv->bank)
+		return;
+
+	if (bank & BIT(0))
+		val |= RTC7301_CONTROL_BANK_SEL_0;
+	if (bank & BIT(1))
+		val |= RTC7301_CONTROL_BANK_SEL_1;
+
+	rtc7301_update_bits(priv, RTC7301_CONTROL,
+			    RTC7301_CONTROL_BANK_SEL_0 |
+			    RTC7301_CONTROL_BANK_SEL_1, val);
+
+	priv->bank = bank;
+}
+
+static void rtc7301_get_time(struct rtc7301_priv *priv, struct rtc_time *tm,
+			     bool alarm)
+{
+	int year;
+
+	tm->tm_sec = rtc7301_read(priv, RTC7301_1_SEC);
+	tm->tm_sec += (rtc7301_read(priv, RTC7301_10_SEC) & ~RTC7301_AE) * 10;
+	tm->tm_min = rtc7301_read(priv, RTC7301_1_MIN);
+	tm->tm_min += (rtc7301_read(priv, RTC7301_10_MIN) & ~RTC7301_AE) * 10;
+	tm->tm_hour = rtc7301_read(priv, RTC7301_1_HOUR);
+	tm->tm_hour += (rtc7301_read(priv, RTC7301_10_HOUR) & ~RTC7301_AE) * 10;
+	tm->tm_mday = rtc7301_read(priv, RTC7301_1_DAY);
+	tm->tm_mday += (rtc7301_read(priv, RTC7301_10_DAY) & ~RTC7301_AE) * 10;
+
+	if (alarm) {
+		tm->tm_wday = -1;
+		tm->tm_mon = -1;
+		tm->tm_year = -1;
+		tm->tm_yday = -1;
+		tm->tm_isdst = -1;
+		return;
+	}
+
+	tm->tm_wday = (rtc7301_read(priv, RTC7301_DAY_OF_WEEK) & ~RTC7301_AE);
+	tm->tm_mon = rtc7301_read(priv, RTC7301_10_MONTH) * 10 +
+		     rtc7301_read(priv, RTC7301_1_MONTH) - 1;
+	year = rtc7301_read(priv, RTC7301_1000_YEAR) * 1000 +
+	       rtc7301_read(priv, RTC7301_100_YEAR) * 100 +
+	       rtc7301_read(priv, RTC7301_10_YEAR) * 10 +
+	       rtc7301_read(priv, RTC7301_1_YEAR);
+
+	tm->tm_year = year - 1900;
+}
+
+static void rtc7301_write_time(struct rtc7301_priv *priv, struct rtc_time *tm,
+			       bool alarm)
+{
+	int year;
+
+	rtc7301_write(priv, tm->tm_sec % 10, RTC7301_1_SEC);
+	rtc7301_write(priv, tm->tm_sec / 10, RTC7301_10_SEC);
+
+	rtc7301_write(priv, tm->tm_min % 10, RTC7301_1_MIN);
+	rtc7301_write(priv, tm->tm_min / 10, RTC7301_10_MIN);
+
+	rtc7301_write(priv, tm->tm_hour % 10, RTC7301_1_HOUR);
+	rtc7301_write(priv, tm->tm_hour / 10, RTC7301_10_HOUR);
+
+	rtc7301_write(priv, tm->tm_mday % 10, RTC7301_1_DAY);
+	rtc7301_write(priv, tm->tm_mday / 10, RTC7301_10_DAY);
+
+	/* Don't care for alarm register */
+	rtc7301_write(priv, alarm ? RTC7301_AE : tm->tm_wday,
+		      RTC7301_DAY_OF_WEEK);
+
+	if (alarm)
+		return;
+
+	rtc7301_write(priv, (tm->tm_mon + 1) % 10, RTC7301_1_MONTH);
+	rtc7301_write(priv, (tm->tm_mon + 1) / 10, RTC7301_10_MONTH);
+
+	year = tm->tm_year + 1900;
+
+	rtc7301_write(priv, year % 10, RTC7301_1_YEAR);
+	rtc7301_write(priv, (year / 10) % 10, RTC7301_10_YEAR);
+	rtc7301_write(priv, (year / 100) % 10, RTC7301_100_YEAR);
+	rtc7301_write(priv, year / 1000, RTC7301_1000_YEAR);
+}
+
+static void rtc7301_alarm_irq(struct rtc7301_priv *priv, unsigned int enabled)
+{
+	rtc7301_update_bits(priv, RTC7301_ALARM_CONTROL,
+			    RTC7301_ALARM_CONTROL_AF |
+			    RTC7301_ALARM_CONTROL_AIE,
+			    enabled ? RTC7301_ALARM_CONTROL_AIE : 0);
+}
+
+static int rtc7301_read_time(struct device *dev, struct rtc_time *tm)
+{
+	struct rtc7301_priv *priv = dev_get_drvdata(dev);
+	unsigned long flags;
+	int err;
+
+	spin_lock_irqsave(&priv->lock, flags);
+
+	rtc7301_select_bank(priv, 0);
+
+	err = rtc7301_wait_while_busy(priv);
+	if (!err)
+		rtc7301_get_time(priv, tm, false);
+
+	spin_unlock_irqrestore(&priv->lock, flags);
+
+	return err ? err : rtc_valid_tm(tm);
+}
+
+static int rtc7301_set_time(struct device *dev, struct rtc_time *tm)
+{
+	struct rtc7301_priv *priv = dev_get_drvdata(dev);
+	unsigned long flags;
+
+	spin_lock_irqsave(&priv->lock, flags);
+
+	rtc7301_stop(priv);
+	usleep_range(200, 300);
+	rtc7301_select_bank(priv, 0);
+	rtc7301_write_time(priv, tm, false);
+	rtc7301_start(priv);
+
+	spin_unlock_irqrestore(&priv->lock, flags);
+
+	return 0;
+}
+
+static int rtc7301_read_alarm(struct device *dev, struct rtc_wkalrm *alarm)
+{
+	struct rtc7301_priv *priv = dev_get_drvdata(dev);
+	unsigned long flags;
+	u8 alrm_ctrl;
+
+	if (priv->irq <= 0)
+		return -EINVAL;
+
+	spin_lock_irqsave(&priv->lock, flags);
+
+	rtc7301_select_bank(priv, 1);
+	rtc7301_get_time(priv, &alarm->time, true);
+
+	alrm_ctrl = rtc7301_read(priv, RTC7301_ALARM_CONTROL);
+
+	alarm->enabled = !!(alrm_ctrl & RTC7301_ALARM_CONTROL_AIE);
+	alarm->pending = !!(alrm_ctrl & RTC7301_ALARM_CONTROL_AF);
+
+	spin_unlock_irqrestore(&priv->lock, flags);
+
+	return 0;
+}
+
+static int rtc7301_set_alarm(struct device *dev, struct rtc_wkalrm *alarm)
+{
+	struct rtc7301_priv *priv = dev_get_drvdata(dev);
+	unsigned long flags;
+
+	if (priv->irq <= 0)
+		return -EINVAL;
+
+	spin_lock_irqsave(&priv->lock, flags);
+
+	rtc7301_select_bank(priv, 1);
+	rtc7301_write_time(priv, &alarm->time, true);
+	rtc7301_alarm_irq(priv, alarm->enabled);
+
+	spin_unlock_irqrestore(&priv->lock, flags);
+
+	return 0;
+}
+
+static int rtc7301_alarm_irq_enable(struct device *dev, unsigned int enabled)
+{
+	struct rtc7301_priv *priv = dev_get_drvdata(dev);
+	unsigned long flags;
+
+	if (priv->irq <= 0)
+		return -EINVAL;
+
+	spin_lock_irqsave(&priv->lock, flags);
+
+	rtc7301_select_bank(priv, 1);
+	rtc7301_alarm_irq(priv, enabled);
+
+	spin_unlock_irqrestore(&priv->lock, flags);
+
+	return 0;
+}
+
+static const struct rtc_class_ops rtc7301_rtc_ops = {
+	.read_time	= rtc7301_read_time,
+	.set_time	= rtc7301_set_time,
+	.read_alarm	= rtc7301_read_alarm,
+	.set_alarm	= rtc7301_set_alarm,
+	.alarm_irq_enable = rtc7301_alarm_irq_enable,
+};
+
+static irqreturn_t rtc7301_irq_handler(int irq, void *dev_id)
+{
+	struct rtc_device *rtc = dev_id;
+	struct rtc7301_priv *priv = dev_get_drvdata(rtc->dev.parent);
+	unsigned long flags;
+	irqreturn_t ret = IRQ_NONE;
+	u8 alrm_ctrl;
+
+	spin_lock_irqsave(&priv->lock, flags);
+
+	rtc7301_select_bank(priv, 1);
+
+	alrm_ctrl = rtc7301_read(priv, RTC7301_ALARM_CONTROL);
+	if (alrm_ctrl & RTC7301_ALARM_CONTROL_AF) {
+		ret = IRQ_HANDLED;
+		rtc7301_alarm_irq(priv, false);
+		rtc_update_irq(rtc, 1, RTC_IRQF | RTC_AF);
+	}
+
+	spin_unlock_irqrestore(&priv->lock, flags);
+
+	return ret;
+}
+
+static void rtc7301_init(struct rtc7301_priv *priv)
+{
+	unsigned long flags;
+
+	spin_lock_irqsave(&priv->lock, flags);
+
+	rtc7301_select_bank(priv, 1);
+	rtc7301_alarm_irq(priv, false);
+
+	rtc7301_select_bank(priv, 2);
+	rtc7301_write(priv, 0, RTC7301_TIMER_CONTROL);
+
+	spin_unlock_irqrestore(&priv->lock, flags);
+}
+
+static int __init rtc7301_rtc_probe(struct platform_device *dev)
+{
+	struct resource *res;
+	void __iomem *regs;
+	struct rtc7301_priv *priv;
+	struct rtc_device *rtc;
+	int ret;
+
+	res = platform_get_resource(dev, IORESOURCE_MEM, 0);
+	if (!res)
+		return -ENODEV;
+
+	priv = devm_kzalloc(&dev->dev, sizeof(*priv), GFP_KERNEL);
+	if (!priv)
+		return -ENOMEM;
+
+	regs = devm_ioremap_resource(&dev->dev, res);
+	if (IS_ERR(regs))
+		return PTR_ERR(regs);
+
+	priv->regmap = devm_regmap_init_mmio(&dev->dev, regs,
+					     &rtc7301_regmap_config);
+	if (IS_ERR(priv->regmap))
+		return PTR_ERR(priv->regmap);
+
+	priv->irq = platform_get_irq(dev, 0);
+
+	spin_lock_init(&priv->lock);
+	priv->bank = -1;
+
+	rtc7301_init(priv);
+
+	platform_set_drvdata(dev, priv);
+
+	rtc = devm_rtc_device_register(&dev->dev, DRV_NAME, &rtc7301_rtc_ops,
+				       THIS_MODULE);
+	if (IS_ERR(rtc))
+		return PTR_ERR(rtc);
+
+	if (priv->irq > 0) {
+		ret = devm_request_irq(&dev->dev, priv->irq,
+				       rtc7301_irq_handler, IRQF_SHARED,
+				       dev_name(&dev->dev), rtc);
+		if (ret) {
+			priv->irq = 0;
+			dev_err(&dev->dev, "unable to request IRQ\n");
+		} else {
+			device_set_wakeup_capable(&dev->dev, true);
+		}
+	}
+
+	return 0;
+}
+
+#ifdef CONFIG_PM_SLEEP
+
+static int rtc7301_suspend(struct device *dev)
+{
+	struct rtc7301_priv *priv = dev_get_drvdata(dev);
+
+	if (device_may_wakeup(dev))
+		enable_irq_wake(priv->irq);
+
+	return 0;
+}
+
+static int rtc7301_resume(struct device *dev)
+{
+	struct rtc7301_priv *priv = dev_get_drvdata(dev);
+
+	if (device_may_wakeup(dev))
+		disable_irq_wake(priv->irq);
+
+	return 0;
+}
+
+#endif
+
+static SIMPLE_DEV_PM_OPS(rtc7301_pm_ops, rtc7301_suspend, rtc7301_resume);
+
+static const struct of_device_id rtc7301_dt_match[] = {
+	{ .compatible = "epson,rtc7301sf" },
+	{ .compatible = "epson,rtc7301dg" },
+	{}
+};
+MODULE_DEVICE_TABLE(of, rtc7301_dt_match);
+
+static struct platform_driver rtc7301_rtc_driver = {
+	.driver	= {
+		.name = DRV_NAME,
+		.of_match_table = rtc7301_dt_match,
+		.pm = &rtc7301_pm_ops,
+	},
+};
+
+module_platform_driver_probe(rtc7301_rtc_driver, rtc7301_rtc_probe);
+
+MODULE_AUTHOR("Akinobu Mita <akinobu.mita@gmail.com>");
+MODULE_LICENSE("GPL");
+MODULE_DESCRIPTION("EPSON TOYOCOM RTC-7301SF/DG Driver");
+MODULE_ALIAS("platform:rtc-r7301");