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

This adds support for EPSON TOYOCOM RTC-7301SF/DG which has parallel
interface compatible with SRAM.

This driver supports basic clock, calendar and alarm functionality.

Tested with Microblaze linux running on Artix7 FPGA board with my own
custom IP for RTC-7301.
Signed-off-by: Akinobu Mita <akinobu.mita@gmail.com>
Acked-by: Rob Herring <robh@kernel.org>
Signed-off-by: Alexandre Belloni <alexandre.belloni@free-electrons.com>

Documentation/devicetree/bindings/rtc/epson,rtc7301.txt

+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>;
+	interrupt-parent = <&axi_intc_0>;
+	interrupts = <3 2>;
+};

drivers/rtc/Kconfig

@@ -1705,6 +1705,17 @@ 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

drivers/rtc/Makefile

@@ -120,6 +120,7 @@ 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

drivers/rtc/rtc-r7301.c

+/*
+ * 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"
+
+#define RTC7301_1_SEC		0x0	/* Bank 0 and Band 1 */
+#define RTC7301_10_SEC		0x1	/* Bank 0 and Band 1 */
+#define RTC7301_AE		BIT(3)
+#define RTC7301_1_MIN		0x2	/* Bank 0 and Band 1 */
+#define RTC7301_10_MIN		0x3	/* Bank 0 and Band 1 */
+#define RTC7301_1_HOUR		0x4	/* Bank 0 and Band 1 */
+#define RTC7301_10_HOUR		0x5	/* Bank 0 and Band 1 */
+#define RTC7301_DAY_OF_WEEK	0x6	/* Bank 0 and Band 1 */
+#define RTC7301_1_DAY		0x7	/* Bank 0 and Band 1 */
+#define RTC7301_10_DAY		0x8	/* Bank 0 and Band 1 */
+#define RTC7301_1_MONTH		0x9	/* Bank 0 */
+#define RTC7301_10_MONTH	0xa	/* Bank 0 */
+#define RTC7301_1_YEAR		0xb	/* Bank 0 */
+#define RTC7301_10_YEAR		0xc	/* Bank 0 */
+#define RTC7301_100_YEAR	0xd	/* Bank 0 */
+#define RTC7301_1000_YEAR	0xe	/* Bank 0 */
+#define RTC7301_ALARM_CONTROL	0xe	/* Bank 1 */
+#define RTC7301_ALARM_CONTROL_AIE	BIT(0)
+#define RTC7301_ALARM_CONTROL_AF	BIT(1)
+#define RTC7301_TIMER_CONTROL	0xe	/* Bank 2 */
+#define RTC7301_TIMER_CONTROL_TIE	BIT(0)
+#define RTC7301_TIMER_CONTROL_TF	BIT(1)
+#define RTC7301_CONTROL		0xf	/* All banks */
+#define RTC7301_CONTROL_BUSY		BIT(0)
+#define RTC7301_CONTROL_STOP		BIT(1)
+#define RTC7301_CONTROL_BANK_SEL_0	BIT(2)
+#define 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, 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");