[PATCH v3 4/4] rtc: stm32: add stm32mp1 rtc support

[Amelie Delaunay <amelie.delaunay@st.com>]

This patch adds support for stm32mp1 RTC.
Some common registers with previous RTC version have a different offset.
It is the case for Control Register (CR) and ALaRMA Register (ALRMAR).
There are also new registers regarding event flags: now, Alarm event flag
is in Status Register (SR) and write 1 in Status Clear Register (SCR) is
required to clear the event.

Signed-off-by: Amelie Delaunay <amelie.delaunay@st.com>
---
 drivers/rtc/rtc-stm32.c | 103 +++++++++++++++++++++++++++++++++++++++++-------
 1 file changed, 89 insertions(+), 14 deletions(-)

diff --git a/drivers/rtc/rtc-stm32.c b/drivers/rtc/rtc-stm32.c
index 8254e38..c5908cf 100644
--- a/drivers/rtc/rtc-stm32.c
+++ b/drivers/rtc/rtc-stm32.c
@@ -11,6 +11,7 @@
 #include <linux/mfd/syscon.h>
 #include <linux/module.h>
 #include <linux/of_device.h>
+#include <linux/pm_wakeirq.h>
 #include <linux/regmap.h>
 #include <linux/rtc.h>
 
@@ -39,7 +40,7 @@
 #define STM32_RTC_CR_ALRAE		BIT(8)
 #define STM32_RTC_CR_ALRAIE		BIT(12)
 
-/* STM32_RTC_ISR bit fields */
+/* STM32_RTC_ISR/STM32_RTC_ICSR bit fields */
 #define STM32_RTC_ISR_ALRAWF		BIT(0)
 #define STM32_RTC_ISR_INITS		BIT(4)
 #define STM32_RTC_ISR_RSF		BIT(5)
@@ -71,21 +72,36 @@
 #define STM32_RTC_ALRMXR_WDAY		GENMASK(27, 24)
 #define STM32_RTC_ALRMXR_DATE_MASK	BIT(31)
 
+/* STM32_RTC_SR/_SCR bit fields */
+#define STM32_RTC_SR_ALRA		BIT(0)
+
+/* STM32_RTC_VERR bit fields */
+#define STM32_RTC_VERR_MINREV_SHIFT	0
+#define STM32_RTC_VERR_MINREV		GENMASK(3, 0)
+#define STM32_RTC_VERR_MAJREV_SHIFT	4
+#define STM32_RTC_VERR_MAJREV		GENMASK(7, 4)
+
 /* STM32_RTC_WPR key constants */
 #define RTC_WPR_1ST_KEY			0xCA
 #define RTC_WPR_2ND_KEY			0x53
 #define RTC_WPR_WRONG_KEY		0xFF
 
+/* Max STM32 RTC register offset is 0x3FC */
+#define UNDEF_REG			0xFFFF
+
 struct stm32_rtc;
 
 struct stm32_rtc_registers {
-	u8 tr;
-	u8 dr;
-	u8 cr;
-	u8 isr;
-	u8 prer;
-	u8 alrmar;
-	u8 wpr;
+	u16 tr;
+	u16 dr;
+	u16 cr;
+	u16 isr;
+	u16 prer;
+	u16 alrmar;
+	u16 wpr;
+	u16 sr;
+	u16 scr;
+	u16 verr;
 };
 
 struct stm32_rtc_events {
@@ -98,6 +114,7 @@ struct stm32_rtc_data {
 	void (*clear_events)(struct stm32_rtc *rtc, unsigned int flags);
 	bool has_pclk;
 	bool need_dbp;
+	bool has_wakeirq;
 };
 
 struct stm32_rtc {
@@ -110,6 +127,7 @@ struct stm32_rtc {
 	struct clk *rtc_ck;
 	const struct stm32_rtc_data *data;
 	int irq_alarm;
+	int wakeirq_alarm;
 };
 
 static void stm32_rtc_wpr_unlock(struct stm32_rtc *rtc)
@@ -193,7 +211,7 @@ static irqreturn_t stm32_rtc_alarm_irq(int irq, void *dev_id)
 
 	mutex_lock(&rtc->rtc_dev->ops_lock);
 
-	status = readl_relaxed(rtc->base + regs->isr);
+	status = readl_relaxed(rtc->base + regs->sr);
 	cr = readl_relaxed(rtc->base + regs->cr);
 
 	if ((status & evts->alra) &&
@@ -325,7 +343,7 @@ static int stm32_rtc_read_alarm(struct device *dev, struct rtc_wkalrm *alrm)
 
 	alrmar = readl_relaxed(rtc->base + regs->alrmar);
 	cr = readl_relaxed(rtc->base + regs->cr);
-	status = readl_relaxed(rtc->base + regs->isr);
+	status = readl_relaxed(rtc->base + regs->sr);
 
 	if (alrmar & STM32_RTC_ALRMXR_DATE_MASK) {
 		/*
@@ -533,6 +551,7 @@ static void stm32_rtc_clear_events(struct stm32_rtc *rtc,
 static const struct stm32_rtc_data stm32_rtc_data = {
 	.has_pclk = false,
 	.need_dbp = true,
+	.has_wakeirq = false,
 	.regs = {
 		.tr = 0x00,
 		.dr = 0x04,
@@ -541,6 +560,9 @@ static const struct stm32_rtc_data stm32_rtc_data = {
 		.prer = 0x10,
 		.alrmar = 0x1C,
 		.wpr = 0x24,
+		.sr = 0x0C, /* set to ISR offset to ease alarm management */
+		.scr = UNDEF_REG,
+		.verr = UNDEF_REG,
 	},
 	.events = {
 		.alra = STM32_RTC_ISR_ALRAF,
@@ -551,6 +573,7 @@ static const struct stm32_rtc_data stm32_rtc_data = {
 static const struct stm32_rtc_data stm32h7_rtc_data = {
 	.has_pclk = true,
 	.need_dbp = true,
+	.has_wakeirq = false,
 	.regs = {
 		.tr = 0x00,
 		.dr = 0x04,
@@ -559,6 +582,9 @@ static const struct stm32_rtc_data stm32h7_rtc_data = {
 		.prer = 0x10,
 		.alrmar = 0x1C,
 		.wpr = 0x24,
+		.sr = 0x0C, /* set to ISR offset to ease alarm management */
+		.scr = UNDEF_REG,
+		.verr = UNDEF_REG,
 	},
 	.events = {
 		.alra = STM32_RTC_ISR_ALRAF,
@@ -566,9 +592,41 @@ static const struct stm32_rtc_data stm32h7_rtc_data = {
 	.clear_events = stm32_rtc_clear_events,
 };
 
+static void stm32mp1_rtc_clear_events(struct stm32_rtc *rtc,
+				      unsigned int flags)
+{
+	struct stm32_rtc_registers regs = rtc->data->regs;
+
+	/* Flags are cleared by writing 1 in RTC_SCR */
+	writel_relaxed(flags, rtc->base + regs.scr);
+}
+
+static const struct stm32_rtc_data stm32mp1_data = {
+	.has_pclk = true,
+	.need_dbp = false,
+	.has_wakeirq = true,
+	.regs = {
+		.tr = 0x00,
+		.dr = 0x04,
+		.cr = 0x18,
+		.isr = 0x0C, /* named RTC_ICSR on stm32mp1 */
+		.prer = 0x10,
+		.alrmar = 0x40,
+		.wpr = 0x24,
+		.sr = 0x50,
+		.scr = 0x5C,
+		.verr = 0x3F4,
+	},
+	.events = {
+		.alra = STM32_RTC_SR_ALRA,
+	},
+	.clear_events = stm32mp1_rtc_clear_events,
+};
+
 static const struct of_device_id stm32_rtc_of_match[] = {
 	{ .compatible = "st,stm32-rtc", .data = &stm32_rtc_data },
 	{ .compatible = "st,stm32h7-rtc", .data = &stm32h7_rtc_data },
+	{ .compatible = "st,stm32mp1-rtc", .data = &stm32mp1_data },
 	{}
 };
 MODULE_DEVICE_TABLE(of, stm32_rtc_of_match);
@@ -727,12 +785,19 @@ static int stm32_rtc_probe(struct platform_device *pdev)
 		goto err;
 	}
 
-	platform_set_drvdata(pdev, rtc);
-
 	ret = device_init_wakeup(&pdev->dev, true);
+	if (rtc->data->has_wakeirq) {
+		rtc->wakeirq_alarm = platform_get_irq(pdev, 1);
+		if (rtc->wakeirq_alarm <= 0)
+			ret = rtc->wakeirq_alarm;
+		else
+			ret = dev_pm_set_dedicated_wake_irq(&pdev->dev,
+							    rtc->wakeirq_alarm);
+	}
 	if (ret)
-		dev_warn(&pdev->dev,
-			 "alarm won't be able to wake up the system");
+		dev_warn(&pdev->dev, "alarm can't wake up the system: %d", ret);
+
+	platform_set_drvdata(pdev, rtc);
 
 	rtc->rtc_dev = devm_rtc_device_register(&pdev->dev, pdev->name,
 						&stm32_rtc_ops, THIS_MODULE);
@@ -760,6 +825,14 @@ static int stm32_rtc_probe(struct platform_device *pdev)
 	if (!(readl_relaxed(rtc->base + regs->isr) & STM32_RTC_ISR_INITS))
 		dev_warn(&pdev->dev, "Date/Time must be initialized\n");
 
+	if (regs->verr != UNDEF_REG) {
+		u32 ver = readl_relaxed(rtc->base + regs->verr);
+
+		dev_info(&pdev->dev, "registered rev:%d.%d\n",
+			 (ver >> STM32_RTC_VERR_MAJREV_SHIFT) & 0xF,
+			 (ver >> STM32_RTC_VERR_MINREV_SHIFT) & 0xF);
+	}
+
 	return 0;
 err:
 	if (rtc->data->has_pclk)
@@ -769,6 +842,7 @@ static int stm32_rtc_probe(struct platform_device *pdev)
 	if (rtc->data->need_dbp)
 		regmap_update_bits(rtc->dbp, rtc->dbp_reg, rtc->dbp_mask, 0);
 
+	dev_pm_clear_wake_irq(&pdev->dev);
 	device_init_wakeup(&pdev->dev, false);
 
 	return ret;
@@ -795,6 +869,7 @@ static int stm32_rtc_remove(struct platform_device *pdev)
 	if (rtc->data->need_dbp)
 		regmap_update_bits(rtc->dbp, rtc->dbp_reg, rtc->dbp_mask, 0);
 
+	dev_pm_clear_wake_irq(&pdev->dev);
 	device_init_wakeup(&pdev->dev, false);
 
 	return 0;
-- 
2.7.4