rtc: add support for the MediaTek MT2712 RTC

This add support for the MediaTek MT2712 RTC. It was SoC based RTC, but
had different architecture compared with MT7622 RTC.

Signed-off-by: Ran Bi <ran.bi@mediatek.com>
Link: https://lore.kernel.org/r/20200226051303.22560-3-ran.bi@mediatek.com
Link: https://lore.kernel.org/r/20200316104701.209293-2-alexandre.belloni@bootlin.com
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>

3 files changed, 432 insertions, 0 deletions

diff --git a/drivers/rtc/Kconfig b/drivers/rtc/Kconfig
index 777047620ec7..7d6cb60ee010 100644
--- a/drivers/rtc/Kconfig
+++ b/drivers/rtc/Kconfig
@@ -1807,6 +1807,16 @@ config RTC_DRV_MOXART
 	   This driver can also be built as a module. If so, the module
 	   will be called rtc-moxart
 
+config RTC_DRV_MT2712
+	tristate "MediaTek MT2712 SoC based RTC"
+	depends on ARCH_MEDIATEK || COMPILE_TEST
+	help
+	  This enables support for the real time clock built in the MediaTek
+	  SoCs for MT2712.
+
+	  This drive can also be built as a module. If so, the module
+	  will be called rtc-mt2712.
+
 config RTC_DRV_MT6397
 	tristate "MediaTek PMIC based RTC"
 	depends on MFD_MT6397 || (COMPILE_TEST && IRQ_DOMAIN)
diff --git a/drivers/rtc/Makefile b/drivers/rtc/Makefile
index 4ac8f19fb631..6c3e93aa36dc 100644
--- a/drivers/rtc/Makefile
+++ b/drivers/rtc/Makefile
@@ -110,6 +110,7 @@ obj-$(CONFIG_RTC_DRV_MESON)	+= rtc-meson.o
 obj-$(CONFIG_RTC_DRV_MOXART)	+= rtc-moxart.o
 obj-$(CONFIG_RTC_DRV_MPC5121)	+= rtc-mpc5121.o
 obj-$(CONFIG_RTC_DRV_MSM6242)	+= rtc-msm6242.o
+obj-$(CONFIG_RTC_DRV_MT2712)	+= rtc-mt2712.o
 obj-$(CONFIG_RTC_DRV_MT6397)	+= rtc-mt6397.o
 obj-$(CONFIG_RTC_DRV_MT7622)	+= rtc-mt7622.o
 obj-$(CONFIG_RTC_DRV_MV)	+= rtc-mv.o
diff --git a/drivers/rtc/rtc-mt2712.c b/drivers/rtc/rtc-mt2712.c
new file mode 100644
index 000000000000..62c20241426d
--- /dev/null
+++ b/drivers/rtc/rtc-mt2712.c
@@ -0,0 +1,421 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (c) 2019 MediaTek Inc.
+ * Author: Ran Bi <ran.bi@mediatek.com>
+ */
+
+#include <linux/delay.h>
+#include <linux/init.h>
+#include <linux/io.h>
+#include <linux/irqdomain.h>
+#include <linux/module.h>
+#include <linux/of_address.h>
+#include <linux/of_irq.h>
+#include <linux/platform_device.h>
+#include <linux/rtc.h>
+
+#define MT2712_BBPU		0x0000
+#define MT2712_BBPU_CLRPKY	BIT(4)
+#define MT2712_BBPU_RELOAD	BIT(5)
+#define MT2712_BBPU_CBUSY	BIT(6)
+#define MT2712_BBPU_KEY		(0x43 << 8)
+
+#define MT2712_IRQ_STA		0x0004
+#define MT2712_IRQ_STA_AL	BIT(0)
+#define MT2712_IRQ_STA_TC	BIT(1)
+
+#define MT2712_IRQ_EN		0x0008
+#define MT2712_IRQ_EN_AL	BIT(0)
+#define MT2712_IRQ_EN_TC	BIT(1)
+#define MT2712_IRQ_EN_ONESHOT	BIT(2)
+
+#define MT2712_CII_EN		0x000c
+
+#define MT2712_AL_MASK		0x0010
+#define MT2712_AL_MASK_DOW	BIT(4)
+
+#define MT2712_TC_SEC		0x0014
+#define MT2712_TC_MIN		0x0018
+#define MT2712_TC_HOU		0x001c
+#define MT2712_TC_DOM		0x0020
+#define MT2712_TC_DOW		0x0024
+#define MT2712_TC_MTH		0x0028
+#define MT2712_TC_YEA		0x002c
+
+#define MT2712_AL_SEC		0x0030
+#define MT2712_AL_MIN		0x0034
+#define MT2712_AL_HOU		0x0038
+#define MT2712_AL_DOM		0x003c
+#define MT2712_AL_DOW		0x0040
+#define MT2712_AL_MTH		0x0044
+#define MT2712_AL_YEA		0x0048
+
+#define MT2712_SEC_MASK		0x003f
+#define MT2712_MIN_MASK		0x003f
+#define MT2712_HOU_MASK		0x001f
+#define MT2712_DOM_MASK		0x001f
+#define MT2712_DOW_MASK		0x0007
+#define MT2712_MTH_MASK		0x000f
+#define MT2712_YEA_MASK		0x007f
+
+#define MT2712_POWERKEY1	0x004c
+#define MT2712_POWERKEY2	0x0050
+#define MT2712_POWERKEY1_KEY	0xa357
+#define MT2712_POWERKEY2_KEY	0x67d2
+
+#define MT2712_CON0		0x005c
+#define MT2712_CON1		0x0060
+
+#define MT2712_PROT		0x0070
+#define MT2712_PROT_UNLOCK1	0x9136
+#define MT2712_PROT_UNLOCK2	0x586a
+
+#define MT2712_WRTGR		0x0078
+
+#define MT2712_RTC_TIMESTAMP_END_2127	4985971199LL
+
+struct mt2712_rtc {
+	struct rtc_device	*rtc;
+	void __iomem		*base;
+	int			irq;
+	u8			irq_wake_enabled;
+	u8			powerlost;
+};
+
+static inline u32 mt2712_readl(struct mt2712_rtc *mt2712_rtc, u32 reg)
+{
+	return readl(mt2712_rtc->base + reg);
+}
+
+static inline void mt2712_writel(struct mt2712_rtc *mt2712_rtc,
+				 u32 reg, u32 val)
+{
+	writel(val, mt2712_rtc->base + reg);
+}
+
+static void mt2712_rtc_write_trigger(struct mt2712_rtc *mt2712_rtc)
+{
+	unsigned long timeout = jiffies + HZ / 10;
+
+	mt2712_writel(mt2712_rtc, MT2712_WRTGR, 1);
+	while (1) {
+		if (!(mt2712_readl(mt2712_rtc, MT2712_BBPU)
+					& MT2712_BBPU_CBUSY))
+			break;
+
+		if (time_after(jiffies, timeout)) {
+			dev_err(&mt2712_rtc->rtc->dev,
+				"%s time out!\n", __func__);
+			break;
+		}
+		cpu_relax();
+	}
+}
+
+static void mt2712_rtc_writeif_unlock(struct mt2712_rtc *mt2712_rtc)
+{
+	mt2712_writel(mt2712_rtc, MT2712_PROT, MT2712_PROT_UNLOCK1);
+	mt2712_rtc_write_trigger(mt2712_rtc);
+	mt2712_writel(mt2712_rtc, MT2712_PROT, MT2712_PROT_UNLOCK2);
+	mt2712_rtc_write_trigger(mt2712_rtc);
+}
+
+static irqreturn_t rtc_irq_handler_thread(int irq, void *data)
+{
+	struct mt2712_rtc *mt2712_rtc = data;
+	u16 irqsta;
+
+	/* Clear interrupt */
+	irqsta = mt2712_readl(mt2712_rtc, MT2712_IRQ_STA);
+	if (irqsta & MT2712_IRQ_STA_AL) {
+		rtc_update_irq(mt2712_rtc->rtc, 1, RTC_IRQF | RTC_AF);
+		return IRQ_HANDLED;
+	}
+
+	return IRQ_NONE;
+}
+
+static void __mt2712_rtc_read_time(struct mt2712_rtc *mt2712_rtc,
+				   struct rtc_time *tm, int *sec)
+{
+	tm->tm_sec  = mt2712_readl(mt2712_rtc, MT2712_TC_SEC)
+			& MT2712_SEC_MASK;
+	tm->tm_min  = mt2712_readl(mt2712_rtc, MT2712_TC_MIN)
+			& MT2712_MIN_MASK;
+	tm->tm_hour = mt2712_readl(mt2712_rtc, MT2712_TC_HOU)
+			& MT2712_HOU_MASK;
+	tm->tm_mday = mt2712_readl(mt2712_rtc, MT2712_TC_DOM)
+			& MT2712_DOM_MASK;
+	tm->tm_mon  = (mt2712_readl(mt2712_rtc, MT2712_TC_MTH) - 1)
+			& MT2712_MTH_MASK;
+	tm->tm_year = (mt2712_readl(mt2712_rtc, MT2712_TC_YEA) + 100)
+			& MT2712_YEA_MASK;
+
+	*sec = mt2712_readl(mt2712_rtc, MT2712_TC_SEC) & MT2712_SEC_MASK;
+}
+
+static int mt2712_rtc_read_time(struct device *dev, struct rtc_time *tm)
+{
+	struct mt2712_rtc *mt2712_rtc = dev_get_drvdata(dev);
+	int sec;
+
+	if (mt2712_rtc->powerlost)
+		return -EINVAL;
+
+	do {
+		__mt2712_rtc_read_time(mt2712_rtc, tm, &sec);
+	} while (sec < tm->tm_sec);	/* SEC has carried */
+
+	return 0;
+}
+
+static int mt2712_rtc_set_time(struct device *dev, struct rtc_time *tm)
+{
+	struct mt2712_rtc *mt2712_rtc = dev_get_drvdata(dev);
+
+	mt2712_writel(mt2712_rtc, MT2712_TC_SEC, tm->tm_sec  & MT2712_SEC_MASK);
+	mt2712_writel(mt2712_rtc, MT2712_TC_MIN, tm->tm_min  & MT2712_MIN_MASK);
+	mt2712_writel(mt2712_rtc, MT2712_TC_HOU, tm->tm_hour & MT2712_HOU_MASK);
+	mt2712_writel(mt2712_rtc, MT2712_TC_DOM, tm->tm_mday & MT2712_DOM_MASK);
+	mt2712_writel(mt2712_rtc, MT2712_TC_MTH,
+		      (tm->tm_mon + 1) & MT2712_MTH_MASK);
+	mt2712_writel(mt2712_rtc, MT2712_TC_YEA,
+		      (tm->tm_year - 100) & MT2712_YEA_MASK);
+
+	mt2712_rtc_write_trigger(mt2712_rtc);
+
+	if (mt2712_rtc->powerlost)
+		mt2712_rtc->powerlost = false;
+
+	return 0;
+}
+
+static int mt2712_rtc_read_alarm(struct device *dev, struct rtc_wkalrm *alm)
+{
+	struct mt2712_rtc *mt2712_rtc = dev_get_drvdata(dev);
+	struct rtc_time *tm = &alm->time;
+	u16 irqen;
+
+	irqen = mt2712_readl(mt2712_rtc, MT2712_IRQ_EN);
+	alm->enabled = !!(irqen & MT2712_IRQ_EN_AL);
+
+	tm->tm_sec  = mt2712_readl(mt2712_rtc, MT2712_AL_SEC) & MT2712_SEC_MASK;
+	tm->tm_min  = mt2712_readl(mt2712_rtc, MT2712_AL_MIN) & MT2712_MIN_MASK;
+	tm->tm_hour = mt2712_readl(mt2712_rtc, MT2712_AL_HOU) & MT2712_HOU_MASK;
+	tm->tm_mday = mt2712_readl(mt2712_rtc, MT2712_AL_DOM) & MT2712_DOM_MASK;
+	tm->tm_mon  = (mt2712_readl(mt2712_rtc, MT2712_AL_MTH) - 1)
+		      & MT2712_MTH_MASK;
+	tm->tm_year = (mt2712_readl(mt2712_rtc, MT2712_AL_YEA) + 100)
+		      & MT2712_YEA_MASK;
+
+	return 0;
+}
+
+static int mt2712_rtc_alarm_irq_enable(struct device *dev,
+				       unsigned int enabled)
+{
+	struct mt2712_rtc *mt2712_rtc = dev_get_drvdata(dev);
+	u16 irqen;
+
+	irqen = mt2712_readl(mt2712_rtc, MT2712_IRQ_EN);
+	if (enabled)
+		irqen |= MT2712_IRQ_EN_AL;
+	else
+		irqen &= ~MT2712_IRQ_EN_AL;
+	mt2712_writel(mt2712_rtc, MT2712_IRQ_EN, irqen);
+	mt2712_rtc_write_trigger(mt2712_rtc);
+
+	return 0;
+}
+
+static int mt2712_rtc_set_alarm(struct device *dev, struct rtc_wkalrm *alm)
+{
+	struct mt2712_rtc *mt2712_rtc = dev_get_drvdata(dev);
+	struct rtc_time *tm = &alm->time;
+
+	dev_dbg(&mt2712_rtc->rtc->dev, "set al time: %ptR, alm en: %d\n",
+		tm, alm->enabled);
+
+	mt2712_writel(mt2712_rtc, MT2712_AL_SEC,
+		      (mt2712_readl(mt2712_rtc, MT2712_AL_SEC)
+		       & ~(MT2712_SEC_MASK)) | (tm->tm_sec  & MT2712_SEC_MASK));
+	mt2712_writel(mt2712_rtc, MT2712_AL_MIN,
+		      (mt2712_readl(mt2712_rtc, MT2712_AL_MIN)
+		       & ~(MT2712_MIN_MASK)) | (tm->tm_min  & MT2712_MIN_MASK));
+	mt2712_writel(mt2712_rtc, MT2712_AL_HOU,
+		      (mt2712_readl(mt2712_rtc, MT2712_AL_HOU)
+		       & ~(MT2712_HOU_MASK)) | (tm->tm_hour & MT2712_HOU_MASK));
+	mt2712_writel(mt2712_rtc, MT2712_AL_DOM,
+		      (mt2712_readl(mt2712_rtc, MT2712_AL_DOM)
+		       & ~(MT2712_DOM_MASK)) | (tm->tm_mday & MT2712_DOM_MASK));
+	mt2712_writel(mt2712_rtc, MT2712_AL_MTH,
+		      (mt2712_readl(mt2712_rtc, MT2712_AL_MTH)
+		       & ~(MT2712_MTH_MASK))
+		      | ((tm->tm_mon + 1) & MT2712_MTH_MASK));
+	mt2712_writel(mt2712_rtc, MT2712_AL_YEA,
+		      (mt2712_readl(mt2712_rtc, MT2712_AL_YEA)
+		       & ~(MT2712_YEA_MASK))
+		      | ((tm->tm_year - 100) & MT2712_YEA_MASK));
+
+	/* mask day of week */
+	mt2712_writel(mt2712_rtc, MT2712_AL_MASK, MT2712_AL_MASK_DOW);
+	mt2712_rtc_write_trigger(mt2712_rtc);
+
+	mt2712_rtc_alarm_irq_enable(dev, alm->enabled);
+
+	return 0;
+}
+
+/* Init RTC register */
+static void mt2712_rtc_hw_init(struct mt2712_rtc *mt2712_rtc)
+{
+	u32 p1, p2;
+
+	mt2712_writel(mt2712_rtc, MT2712_BBPU,
+		      MT2712_BBPU_KEY | MT2712_BBPU_RELOAD);
+
+	mt2712_writel(mt2712_rtc, MT2712_CII_EN, 0);
+	mt2712_writel(mt2712_rtc, MT2712_AL_MASK, 0);
+	/* necessary before set MT2712_POWERKEY */
+	mt2712_writel(mt2712_rtc, MT2712_CON0, 0x4848);
+	mt2712_writel(mt2712_rtc, MT2712_CON1, 0x0048);
+
+	mt2712_rtc_write_trigger(mt2712_rtc);
+
+	p1 = mt2712_readl(mt2712_rtc, MT2712_POWERKEY1);
+	p2 = mt2712_readl(mt2712_rtc, MT2712_POWERKEY2);
+	if (p1 != MT2712_POWERKEY1_KEY || p2 != MT2712_POWERKEY2_KEY) {
+		mt2712_rtc->powerlost = true;
+		dev_dbg(&mt2712_rtc->rtc->dev,
+			"powerkey not set (lost power)\n");
+	} else {
+		mt2712_rtc->powerlost = false;
+	}
+
+	/* RTC need POWERKEY1/2 match, then goto normal work mode */
+	mt2712_writel(mt2712_rtc, MT2712_POWERKEY1, MT2712_POWERKEY1_KEY);
+	mt2712_writel(mt2712_rtc, MT2712_POWERKEY2, MT2712_POWERKEY2_KEY);
+	mt2712_rtc_write_trigger(mt2712_rtc);
+
+	mt2712_rtc_writeif_unlock(mt2712_rtc);
+}
+
+static const struct rtc_class_ops mt2712_rtc_ops = {
+	.read_time	= mt2712_rtc_read_time,
+	.set_time	= mt2712_rtc_set_time,
+	.read_alarm	= mt2712_rtc_read_alarm,
+	.set_alarm	= mt2712_rtc_set_alarm,
+	.alarm_irq_enable = mt2712_rtc_alarm_irq_enable,
+};
+
+static int mt2712_rtc_probe(struct platform_device *pdev)
+{
+	struct resource *res;
+	struct mt2712_rtc *mt2712_rtc;
+	int ret;
+
+	mt2712_rtc = devm_kzalloc(&pdev->dev,
+				  sizeof(struct mt2712_rtc), GFP_KERNEL);
+	if (!mt2712_rtc)
+		return -ENOMEM;
+
+	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+	mt2712_rtc->base = devm_ioremap_resource(&pdev->dev, res);
+	if (IS_ERR(mt2712_rtc->base))
+		return PTR_ERR(mt2712_rtc->base);
+
+	/* rtc hw init */
+	mt2712_rtc_hw_init(mt2712_rtc);
+
+	mt2712_rtc->irq = platform_get_irq(pdev, 0);
+	if (mt2712_rtc->irq < 0) {
+		dev_err(&pdev->dev, "No IRQ resource\n");
+		return mt2712_rtc->irq;
+	}
+
+	platform_set_drvdata(pdev, mt2712_rtc);
+
+	mt2712_rtc->rtc = devm_rtc_allocate_device(&pdev->dev);
+	if (IS_ERR(mt2712_rtc->rtc))
+		return PTR_ERR(mt2712_rtc->rtc);
+
+	ret = devm_request_threaded_irq(&pdev->dev, mt2712_rtc->irq, NULL,
+					rtc_irq_handler_thread,
+					IRQF_ONESHOT | IRQF_TRIGGER_LOW,
+					dev_name(&mt2712_rtc->rtc->dev),
+					mt2712_rtc);
+	if (ret) {
+		dev_err(&pdev->dev, "Failed to request alarm IRQ: %d: %d\n",
+			mt2712_rtc->irq, ret);
+		return ret;
+	}
+
+	device_init_wakeup(&pdev->dev, true);
+
+	mt2712_rtc->rtc->ops = &mt2712_rtc_ops;
+	mt2712_rtc->rtc->range_min = RTC_TIMESTAMP_BEGIN_2000;
+	mt2712_rtc->rtc->range_max = MT2712_RTC_TIMESTAMP_END_2127;
+
+	ret = rtc_register_device(mt2712_rtc->rtc);
+	if (ret) {
+		dev_err(&pdev->dev, "register rtc device failed\n");
+		return ret;
+	}
+
+	return 0;
+}
+
+#ifdef CONFIG_PM_SLEEP
+static int mt2712_rtc_suspend(struct device *dev)
+{
+	int wake_status = 0;
+	struct mt2712_rtc *mt2712_rtc = dev_get_drvdata(dev);
+
+	if (device_may_wakeup(dev)) {
+		wake_status = enable_irq_wake(mt2712_rtc->irq);
+		if (!wake_status)
+			mt2712_rtc->irq_wake_enabled = true;
+	}
+
+	return 0;
+}
+
+static int mt2712_rtc_resume(struct device *dev)
+{
+	int wake_status = 0;
+	struct mt2712_rtc *mt2712_rtc = dev_get_drvdata(dev);
+
+	if (device_may_wakeup(dev) && mt2712_rtc->irq_wake_enabled) {
+		wake_status = disable_irq_wake(mt2712_rtc->irq);
+		if (!wake_status)
+			mt2712_rtc->irq_wake_enabled = false;
+	}
+
+	return 0;
+}
+
+static SIMPLE_DEV_PM_OPS(mt2712_pm_ops, mt2712_rtc_suspend,
+			 mt2712_rtc_resume);
+#endif
+
+static const struct of_device_id mt2712_rtc_of_match[] = {
+	{ .compatible = "mediatek,mt2712-rtc", },
+	{ },
+};
+
+MODULE_DEVICE_TABLE(of, mt2712_rtc_of_match);
+
+static struct platform_driver mt2712_rtc_driver = {
+	.driver = {
+		.name = "mt2712-rtc",
+		.of_match_table = mt2712_rtc_of_match,
+		.pm = &mt2712_pm_ops,
+	},
+	.probe  = mt2712_rtc_probe,
+};
+
+module_platform_driver(mt2712_rtc_driver);
+
+MODULE_DESCRIPTION("MediaTek MT2712 SoC based RTC Driver");
+MODULE_AUTHOR("Ran Bi <ran.bi@mediatek.com>");
+MODULE_LICENSE("GPL");