rtc: mediatek: Add MT6397 RTC driver

Add Mediatek MT6397 RTC driver

Signed-off-by: Tianping Fang <[e-mail]>
Signed-off-by: Eddie Huang <[e-mail]>
Signed-off-by: Alexandre Belloni <[e-mail]>

drivers/rtc/Kconfig

···
 	   This driver can also be built as a module. If so, the module
 	   will be called rtc-moxart
 
+config RTC_DRV_MT6397
+	tristate "Mediatek Real Time Clock driver"
+	depends on MFD_MT6397 || COMPILE_TEST
+	help
+	  This selects the Mediatek(R) RTC driver. RTC is part of Mediatek
+	  MT6397 PMIC. You should enable MT6397 PMIC MFD before select
+	  Mediatek(R) RTC driver.
+
+	  If you want to use Mediatek(R) RTC interface, select Y or M here.
+
 config RTC_DRV_XGENE
 	tristate "APM X-Gene RTC"
 	depends on HAS_IOMEM

drivers/rtc/Makefile

···
 obj-$(CONFIG_RTC_DRV_XGENE)	+= rtc-xgene.o
 obj-$(CONFIG_RTC_DRV_SIRFSOC)	+= rtc-sirfsoc.o
 obj-$(CONFIG_RTC_DRV_MOXART)	+= rtc-moxart.o
+obj-$(CONFIG_RTC_DRV_MT6397)	+= rtc-mt6397.o

drivers/rtc/rtc-mt6397.c

···
+/*
+* Copyright (c) 2014-2015 MediaTek Inc.
+* Author: Tianping.Fang <[e-mail]>
+*
+* 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.
+*
+* This program is distributed in the hope that it will be useful,
+* but WITHOUT ANY WARRANTY; without even the implied warranty of
+* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+* GNU General Public License for more details.
+*/
+
+#include <linux/delay.h>
+#include <linux/init.h>
+#include <linux/module.h>
+#include <linux/regmap.h>
+#include <linux/rtc.h>
+#include <linux/irqdomain.h>
+#include <linux/platform_device.h>
+#include <linux/of_address.h>
+#include <linux/of_irq.h>
+#include <linux/io.h>
+#include <linux/mfd/mt6397/core.h>
+
+#define RTC_BBPU		0x0000
+#define RTC_BBPU_CBUSY		BIT(6)
+
+#define RTC_WRTGR		0x003c
+
+#define RTC_IRQ_STA		0x0002
+#define RTC_IRQ_STA_AL		BIT(0)
+#define RTC_IRQ_STA_LP		BIT(3)
+
+#define RTC_IRQ_EN		0x0004
+#define RTC_IRQ_EN_AL		BIT(0)
+#define RTC_IRQ_EN_ONESHOT	BIT(2)
+#define RTC_IRQ_EN_LP		BIT(3)
+#define RTC_IRQ_EN_ONESHOT_AL	(RTC_IRQ_EN_ONESHOT | RTC_IRQ_EN_AL)
+
+#define RTC_AL_MASK		0x0008
+#define RTC_AL_MASK_DOW		BIT(4)
+
+#define RTC_TC_SEC		0x000a
+/* Min, Hour, Dom... register offset to RTC_TC_SEC */
+#define RTC_OFFSET_SEC		0
+#define RTC_OFFSET_MIN		1
+#define RTC_OFFSET_HOUR		2
+#define RTC_OFFSET_DOM		3
+#define RTC_OFFSET_DOW		4
+#define RTC_OFFSET_MTH		5
+#define RTC_OFFSET_YEAR		6
+#define RTC_OFFSET_COUNT	7
+
+#define RTC_AL_SEC		0x0018
+
+#define RTC_PDN2		0x002e
+#define RTC_PDN2_PWRON_ALARM	BIT(4)
+
+#define RTC_MIN_YEAR		1968
+#define RTC_BASE_YEAR		1900
+#define RTC_NUM_YEARS		128
+#define RTC_MIN_YEAR_OFFSET	(RTC_MIN_YEAR - RTC_BASE_YEAR)
+
+struct mt6397_rtc {
+	struct device		*dev;
+	struct rtc_device	*rtc_dev;
+	struct mutex		lock;
+	struct regmap		*regmap;
+	int			irq;
+	u32			addr_base;
+};
+
+static int mtk_rtc_write_trigger(struct mt6397_rtc *rtc)
+{
+	unsigned long timeout = jiffies + HZ;
+	int ret;
+	u32 data;
+
+	ret = regmap_write(rtc->regmap, rtc->addr_base + RTC_WRTGR, 1);
+	if (ret < 0)
+		return ret;
+
+	while (1) {
+		ret = regmap_read(rtc->regmap, rtc->addr_base + RTC_BBPU,
+				  &data);
+		if (ret < 0)
+			break;
+		if (!(data & RTC_BBPU_CBUSY))
+			break;
+		if (time_after(jiffies, timeout)) {
+			ret = -ETIMEDOUT;
+			break;
+		}
+		cpu_relax();
+	}
+
+	return ret;
+}
+
+static irqreturn_t mtk_rtc_irq_handler_thread(int irq, void *data)
+{
+	struct mt6397_rtc *rtc = data;
+	u32 irqsta, irqen;
+	int ret;
+
+	ret = regmap_read(rtc->regmap, rtc->addr_base + RTC_IRQ_STA, &irqsta);
+	if ((ret >= 0) && (irqsta & RTC_IRQ_STA_AL)) {
+		rtc_update_irq(rtc->rtc_dev, 1, RTC_IRQF | RTC_AF);
+		irqen = irqsta & ~RTC_IRQ_EN_AL;
+		mutex_lock(&rtc->lock);
+		if (regmap_write(rtc->regmap, rtc->addr_base + RTC_IRQ_EN,
+				 irqen) < 0)
+			mtk_rtc_write_trigger(rtc);
+		mutex_unlock(&rtc->lock);
+
+		return IRQ_HANDLED;
+	}
+
+	return IRQ_NONE;
+}
+
+static int __mtk_rtc_read_time(struct mt6397_rtc *rtc,
+			       struct rtc_time *tm, int *sec)
+{
+	int ret;
+	u16 data[RTC_OFFSET_COUNT];
+
+	mutex_lock(&rtc->lock);
+	ret = regmap_bulk_read(rtc->regmap, rtc->addr_base + RTC_TC_SEC,
+			       data, RTC_OFFSET_COUNT);
+	if (ret < 0)
+		goto exit;
+
+	tm->tm_sec = data[RTC_OFFSET_SEC];
+	tm->tm_min = data[RTC_OFFSET_MIN];
+	tm->tm_hour = data[RTC_OFFSET_HOUR];
+	tm->tm_mday = data[RTC_OFFSET_DOM];
+	tm->tm_mon = data[RTC_OFFSET_MTH];
+	tm->tm_year = data[RTC_OFFSET_YEAR];
+
+	ret = regmap_read(rtc->regmap, rtc->addr_base + RTC_TC_SEC, sec);
+exit:
+	mutex_unlock(&rtc->lock);
+	return ret;
+}
+
+static int mtk_rtc_read_time(struct device *dev, struct rtc_time *tm)
+{
+	time64_t time;
+	struct mt6397_rtc *rtc = dev_get_drvdata(dev);
+	int sec, ret;
+
+	do {
+		ret = __mtk_rtc_read_time(rtc, tm, &sec);
+		if (ret < 0)
+			goto exit;
+	} while (sec < tm->tm_sec);
+
+	/* HW register use 7 bits to store year data, minus
+	 * RTC_MIN_YEAR_OFFSET before write year data to register, and plus
+	 * RTC_MIN_YEAR_OFFSET back after read year from register
+	 */
+	tm->tm_year += RTC_MIN_YEAR_OFFSET;
+
+	/* HW register start mon from one, but tm_mon start from zero. */
+	tm->tm_mon--;
+	time = rtc_tm_to_time64(tm);
+
+	/* rtc_tm_to_time64 covert Gregorian date to seconds since
+	 * 01-01-1970 00:00:00, and this date is Thursday.
+	 */
+	tm->tm_wday = (time / 86400 + 4) % 7;
+
+exit:
+	return ret;
+}
+
+static int mtk_rtc_set_time(struct device *dev, struct rtc_time *tm)
+{
+	struct mt6397_rtc *rtc = dev_get_drvdata(dev);
+	int ret;
+	u16 data[RTC_OFFSET_COUNT];
+
+	tm->tm_year -= RTC_MIN_YEAR_OFFSET;
+	tm->tm_mon++;
+
+	data[RTC_OFFSET_SEC] = tm->tm_sec;
+	data[RTC_OFFSET_MIN] = tm->tm_min;
+	data[RTC_OFFSET_HOUR] = tm->tm_hour;
+	data[RTC_OFFSET_DOM] = tm->tm_mday;
+	data[RTC_OFFSET_MTH] = tm->tm_mon;
+	data[RTC_OFFSET_YEAR] = tm->tm_year;
+
+	mutex_lock(&rtc->lock);
+	ret = regmap_bulk_write(rtc->regmap, rtc->addr_base + RTC_TC_SEC,
+				data, RTC_OFFSET_COUNT);
+	if (ret < 0)
+		goto exit;
+
+	/* Time register write to hardware after call trigger function */
+	ret = mtk_rtc_write_trigger(rtc);
+
+exit:
+	mutex_unlock(&rtc->lock);
+	return ret;
+}
+
+static int mtk_rtc_read_alarm(struct device *dev, struct rtc_wkalrm *alm)
+{
+	struct rtc_time *tm = &alm->time;
+	struct mt6397_rtc *rtc = dev_get_drvdata(dev);
+	u32 irqen, pdn2;
+	int ret;
+	u16 data[RTC_OFFSET_COUNT];
+
+	mutex_lock(&rtc->lock);
+	ret = regmap_read(rtc->regmap, rtc->addr_base + RTC_IRQ_EN, &irqen);
+	if (ret < 0)
+		goto err_exit;
+	ret = regmap_read(rtc->regmap, rtc->addr_base + RTC_PDN2, &pdn2);
+	if (ret < 0)
+		goto err_exit;
+
+	ret = regmap_bulk_read(rtc->regmap, rtc->addr_base + RTC_AL_SEC,
+			       data, RTC_OFFSET_COUNT);
+	if (ret < 0)
+		goto err_exit;
+
+	alm->enabled = !!(irqen & RTC_IRQ_EN_AL);
+	alm->pending = !!(pdn2 & RTC_PDN2_PWRON_ALARM);
+	mutex_unlock(&rtc->lock);
+
+	tm->tm_sec = data[RTC_OFFSET_SEC];
+	tm->tm_min = data[RTC_OFFSET_MIN];
+	tm->tm_hour = data[RTC_OFFSET_HOUR];
+	tm->tm_mday = data[RTC_OFFSET_DOM];
+	tm->tm_mon = data[RTC_OFFSET_MTH];
+	tm->tm_year = data[RTC_OFFSET_YEAR];
+
+	tm->tm_year += RTC_MIN_YEAR_OFFSET;
+	tm->tm_mon--;
+
+	return 0;
+err_exit:
+	mutex_unlock(&rtc->lock);
+	return ret;
+}
+
+static int mtk_rtc_set_alarm(struct device *dev, struct rtc_wkalrm *alm)
+{
+	struct rtc_time *tm = &alm->time;
+	struct mt6397_rtc *rtc = dev_get_drvdata(dev);
+	int ret;
+	u16 data[RTC_OFFSET_COUNT];
+
+	tm->tm_year -= RTC_MIN_YEAR_OFFSET;
+	tm->tm_mon++;
+
+	data[RTC_OFFSET_SEC] = tm->tm_sec;
+	data[RTC_OFFSET_MIN] = tm->tm_min;
+	data[RTC_OFFSET_HOUR] = tm->tm_hour;
+	data[RTC_OFFSET_DOM] = tm->tm_mday;
+	data[RTC_OFFSET_MTH] = tm->tm_mon;
+	data[RTC_OFFSET_YEAR] = tm->tm_year;
+
+	mutex_lock(&rtc->lock);
+	if (alm->enabled) {
+		ret = regmap_bulk_write(rtc->regmap,
+					rtc->addr_base + RTC_AL_SEC,
+					data, RTC_OFFSET_COUNT);
+		if (ret < 0)
+			goto exit;
+		ret = regmap_write(rtc->regmap, rtc->addr_base + RTC_AL_MASK,
+				   RTC_AL_MASK_DOW);
+		if (ret < 0)
+			goto exit;
+		ret = regmap_update_bits(rtc->regmap,
+					 rtc->addr_base + RTC_IRQ_EN,
+					 RTC_IRQ_EN_ONESHOT_AL,
+					 RTC_IRQ_EN_ONESHOT_AL);
+		if (ret < 0)
+			goto exit;
+	} else {
+		ret = regmap_update_bits(rtc->regmap,
+					 rtc->addr_base + RTC_IRQ_EN,
+					 RTC_IRQ_EN_ONESHOT_AL, 0);
+		if (ret < 0)
+			goto exit;
+	}
+
+	/* All alarm time register write to hardware after calling
+	 * mtk_rtc_write_trigger. This can avoid race condition if alarm
+	 * occur happen during writing alarm time register.
+	 */
+	ret = mtk_rtc_write_trigger(rtc);
+exit:
+	mutex_unlock(&rtc->lock);
+	return ret;
+}
+
+static struct rtc_class_ops mtk_rtc_ops = {
+	.read_time  = mtk_rtc_read_time,
+	.set_time   = mtk_rtc_set_time,
+	.read_alarm = mtk_rtc_read_alarm,
+	.set_alarm  = mtk_rtc_set_alarm,
+};
+
+static int mtk_rtc_probe(struct platform_device *pdev)
+{
+	struct resource *res;
+	struct mt6397_chip *mt6397_chip = dev_get_drvdata(pdev->dev.parent);
+	struct mt6397_rtc *rtc;
+	int ret;
+
+	rtc = devm_kzalloc(&pdev->dev, sizeof(struct mt6397_rtc), GFP_KERNEL);
+	if (!rtc)
+		return -ENOMEM;
+
+	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+	rtc->addr_base = res->start;
+
+	res = platform_get_resource(pdev, IORESOURCE_IRQ, 0);
+	rtc->irq = irq_create_mapping(mt6397_chip->irq_domain, res->start);
+	if (rtc->irq <= 0)
+		return -EINVAL;
+
+	rtc->regmap = mt6397_chip->regmap;
+	rtc->dev = &pdev->dev;
+	mutex_init(&rtc->lock);
+
+	platform_set_drvdata(pdev, rtc);
+
+	ret = request_threaded_irq(rtc->irq, NULL,
+				   mtk_rtc_irq_handler_thread,
+				   IRQF_ONESHOT | IRQF_TRIGGER_HIGH,
+				   "mt6397-rtc", rtc);
+	if (ret) {
+		dev_err(&pdev->dev, "Failed to request alarm IRQ: %d: %d\n",
+			rtc->irq, ret);
+		goto out_dispose_irq;
+	}
+
+	rtc->rtc_dev = rtc_device_register("mt6397-rtc", &pdev->dev,
+					   &mtk_rtc_ops, THIS_MODULE);
+	if (IS_ERR(rtc->rtc_dev)) {
+		dev_err(&pdev->dev, "register rtc device failed\n");
+		ret = PTR_ERR(rtc->rtc_dev);
+		goto out_free_irq;
+	}
+
+	device_init_wakeup(&pdev->dev, 1);
+
+	return 0;
+
+out_free_irq:
+	free_irq(rtc->irq, rtc->rtc_dev);
+out_dispose_irq:
+	irq_dispose_mapping(rtc->irq);
+	return ret;
+}
+
+static int mtk_rtc_remove(struct platform_device *pdev)
+{
+	struct mt6397_rtc *rtc = platform_get_drvdata(pdev);
+
+	rtc_device_unregister(rtc->rtc_dev);
+	free_irq(rtc->irq, rtc->rtc_dev);
+	irq_dispose_mapping(rtc->irq);
+
+	return 0;
+}
+
+static const struct of_device_id mt6397_rtc_of_match[] = {
+	{ .compatible = "mediatek,mt6397-rtc", },
+	{ }
+};
+
+static struct platform_driver mtk_rtc_driver = {
+	.driver = {
+		.name = "mt6397-rtc",
+		.of_match_table = mt6397_rtc_of_match,
+	},
+	.probe	= mtk_rtc_probe,
+	.remove = mtk_rtc_remove,
+};
+
+module_platform_driver(mtk_rtc_driver);
+
+MODULE_LICENSE("GPL v2");
+MODULE_AUTHOR("Tianping Fang <[e-mail]>");
+MODULE_DESCRIPTION("RTC Driver for MediaTek MT6397 PMIC");
+MODULE_ALIAS("platform:mt6397-rtc");