rtc: Add rtc driver for stm32mp1

Add support of STM32MP1 rtc driver.
Enable it for basic and trusted configurations.

Signed-off-by: Benjamin Gaignard <benjamin.gaignard@st.com>

3 files changed, 330 insertions, 0 deletions

diff --git a/drivers/rtc/Kconfig b/drivers/rtc/Kconfig
index 532e94d337..0b58a18f5f 100644
--- a/drivers/rtc/Kconfig
+++ b/drivers/rtc/Kconfig
@@ -120,4 +120,10 @@ config RTC_M41T62
 	  Enable driver for ST's M41T62 compatible RTC devices (like RV-4162).
 	  It is a serial (I2C) real-time clock (RTC) with alarm.
 
+config RTC_STM32
+	bool "Enable STM32 RTC driver"
+	depends on DM_RTC
+	help
+	  Enable STM32 RTC driver. This driver supports the rtc that is present
+	  on some STM32 SoCs.
 endmenu
diff --git a/drivers/rtc/Makefile b/drivers/rtc/Makefile
index 915adb87fe..f97a669982 100644
--- a/drivers/rtc/Makefile
+++ b/drivers/rtc/Makefile
@@ -51,5 +51,6 @@ obj-$(CONFIG_RTC_RX8025) += rx8025.o
 obj-$(CONFIG_RTC_RX8010SJ) += rx8010sj.o
 obj-$(CONFIG_RTC_S3C24X0) += s3c24x0_rtc.o
 obj-$(CONFIG_RTC_S35392A) += s35392a.o
+obj-$(CONFIG_RTC_STM32) += stm32_rtc.o
 obj-$(CONFIG_SANDBOX) += sandbox_rtc.o
 obj-$(CONFIG_RTC_X1205) += x1205.o
diff --git a/drivers/rtc/stm32_rtc.c b/drivers/rtc/stm32_rtc.c
new file mode 100644
index 0000000000..abd339076a
--- /dev/null
+++ b/drivers/rtc/stm32_rtc.c
@@ -0,0 +1,323 @@
+// SPDX-License-Identifier: GPL-2.0+ OR BSD-3-Clause
+/*
+ * Copyright (C) 2019, STMicroelectronics - All Rights Reserved
+ */
+#include <common.h>
+#include <clk.h>
+#include <dm.h>
+#include <rtc.h>
+#include <asm/io.h>
+#include <linux/iopoll.h>
+
+#define STM32_RTC_TR		0x00
+#define STM32_RTC_DR		0x04
+#define STM32_RTC_ISR		0x0C
+#define STM32_RTC_PRER		0x10
+#define STM32_RTC_CR		0x18
+#define STM32_RTC_WPR		0x24
+
+/* STM32_RTC_TR bit fields  */
+#define STM32_RTC_SEC_SHIFT	0
+#define STM32_RTC_SEC		GENMASK(6, 0)
+#define STM32_RTC_MIN_SHIFT	8
+#define STM32_RTC_MIN		GENMASK(14, 8)
+#define STM32_RTC_HOUR_SHIFT	16
+#define STM32_RTC_HOUR		GENMASK(21, 16)
+
+/* STM32_RTC_DR bit fields */
+#define STM32_RTC_DATE_SHIFT	0
+#define STM32_RTC_DATE		GENMASK(5, 0)
+#define STM32_RTC_MONTH_SHIFT	8
+#define STM32_RTC_MONTH		GENMASK(12, 8)
+#define STM32_RTC_WDAY_SHIFT	13
+#define STM32_RTC_WDAY		GENMASK(15, 13)
+#define STM32_RTC_YEAR_SHIFT	16
+#define STM32_RTC_YEAR		GENMASK(23, 16)
+
+/* STM32_RTC_CR bit fields */
+#define STM32_RTC_CR_FMT	BIT(6)
+
+/* STM32_RTC_ISR/STM32_RTC_ICSR bit fields */
+#define STM32_RTC_ISR_INITS	BIT(4)
+#define STM32_RTC_ISR_RSF	BIT(5)
+#define STM32_RTC_ISR_INITF	BIT(6)
+#define STM32_RTC_ISR_INIT	BIT(7)
+
+/* STM32_RTC_PRER bit fields */
+#define STM32_RTC_PRER_PRED_S_SHIFT	0
+#define STM32_RTC_PRER_PRED_S		GENMASK(14, 0)
+#define STM32_RTC_PRER_PRED_A_SHIFT	16
+#define STM32_RTC_PRER_PRED_A		GENMASK(22, 16)
+
+/* STM32_RTC_WPR key constants */
+#define RTC_WPR_1ST_KEY		0xCA
+#define RTC_WPR_2ND_KEY		0x53
+#define RTC_WPR_WRONG_KEY	0xFF
+
+struct stm32_rtc_priv {
+	fdt_addr_t base;
+};
+
+static int stm32_rtc_get(struct udevice *dev, struct rtc_time *tm)
+{
+	struct stm32_rtc_priv *priv = dev_get_priv(dev);
+	u32 tr, dr;
+
+	tr = readl(priv->base + STM32_RTC_TR);
+	dr = readl(priv->base + STM32_RTC_DR);
+
+	tm->tm_sec = bcd2bin((tr & STM32_RTC_SEC) >> STM32_RTC_SEC_SHIFT);
+	tm->tm_min = bcd2bin((tr & STM32_RTC_MIN) >> STM32_RTC_MIN_SHIFT);
+	tm->tm_hour = bcd2bin((tr & STM32_RTC_HOUR) >> STM32_RTC_HOUR_SHIFT);
+
+	tm->tm_mday = bcd2bin((dr & STM32_RTC_DATE) >> STM32_RTC_DATE_SHIFT);
+	tm->tm_mon = bcd2bin((dr & STM32_RTC_MONTH) >> STM32_RTC_MONTH_SHIFT);
+	tm->tm_year = bcd2bin((dr & STM32_RTC_YEAR) >> STM32_RTC_YEAR_SHIFT);
+	tm->tm_wday = bcd2bin((dr & STM32_RTC_WDAY) >> STM32_RTC_WDAY_SHIFT);
+	tm->tm_yday = 0;
+	tm->tm_isdst = 0;
+
+	dev_dbg(dev, "Get DATE: %4d-%02d-%02d (wday=%d)  TIME: %2d:%02d:%02d\n",
+		tm->tm_year, tm->tm_mon, tm->tm_mday, tm->tm_wday,
+		tm->tm_hour, tm->tm_min, tm->tm_sec);
+
+	return 0;
+}
+
+static void stm32_rtc_unlock(struct udevice *dev)
+{
+	struct stm32_rtc_priv *priv = dev_get_priv(dev);
+
+	writel(RTC_WPR_1ST_KEY, priv->base + STM32_RTC_WPR);
+	writel(RTC_WPR_2ND_KEY, priv->base + STM32_RTC_WPR);
+}
+
+static void stm32_rtc_lock(struct udevice *dev)
+{
+	struct stm32_rtc_priv *priv = dev_get_priv(dev);
+
+	writel(RTC_WPR_WRONG_KEY, priv->base + STM32_RTC_WPR);
+}
+
+static int stm32_rtc_enter_init_mode(struct udevice *dev)
+{
+	struct stm32_rtc_priv *priv = dev_get_priv(dev);
+	u32 isr = readl(priv->base + STM32_RTC_ISR);
+
+	if (!(isr & STM32_RTC_ISR_INITF)) {
+		isr |= STM32_RTC_ISR_INIT;
+		writel(isr, priv->base + STM32_RTC_ISR);
+
+		return readl_poll_timeout(priv->base + STM32_RTC_ISR,
+					  isr,
+					  (isr & STM32_RTC_ISR_INITF),
+					  100000);
+	}
+
+	return 0;
+}
+
+static int stm32_rtc_wait_sync(struct udevice *dev)
+{
+	struct stm32_rtc_priv *priv = dev_get_priv(dev);
+	u32 isr = readl(priv->base + STM32_RTC_ISR);
+
+	isr &= ~STM32_RTC_ISR_RSF;
+	writel(isr, priv->base + STM32_RTC_ISR);
+
+	/*
+	 * Wait for RSF to be set to ensure the calendar registers are
+	 * synchronised, it takes around 2 rtc_ck clock cycles
+	 */
+	return readl_poll_timeout(priv->base + STM32_RTC_ISR,
+				  isr, (isr & STM32_RTC_ISR_RSF),
+				  100000);
+}
+
+static void stm32_rtc_exit_init_mode(struct udevice *dev)
+{
+	struct stm32_rtc_priv *priv = dev_get_priv(dev);
+	u32 isr = readl(priv->base + STM32_RTC_ISR);
+
+	isr &= ~STM32_RTC_ISR_INIT;
+	writel(isr, priv->base + STM32_RTC_ISR);
+}
+
+static int stm32_rtc_set_time(struct udevice *dev, u32 time, u32 date)
+{
+	struct stm32_rtc_priv *priv = dev_get_priv(dev);
+	int ret;
+
+	stm32_rtc_unlock(dev);
+
+	ret = stm32_rtc_enter_init_mode(dev);
+	if (ret)
+		goto lock;
+
+	writel(time, priv->base + STM32_RTC_TR);
+	writel(date, priv->base + STM32_RTC_DR);
+
+	stm32_rtc_exit_init_mode(dev);
+
+	ret = stm32_rtc_wait_sync(dev);
+
+lock:
+	stm32_rtc_lock(dev);
+	return ret;
+}
+
+static int stm32_rtc_set(struct udevice *dev, const struct rtc_time *tm)
+{
+	u32 t, d;
+
+	dev_dbg(dev, "Set DATE: %4d-%02d-%02d (wday=%d)  TIME: %2d:%02d:%02d\n",
+		tm->tm_year, tm->tm_mon, tm->tm_mday, tm->tm_wday,
+		tm->tm_hour, tm->tm_min, tm->tm_sec);
+
+	/* Time in BCD format */
+	t = (bin2bcd(tm->tm_sec) << STM32_RTC_SEC_SHIFT) & STM32_RTC_SEC;
+	t |= (bin2bcd(tm->tm_min) << STM32_RTC_MIN_SHIFT) & STM32_RTC_MIN;
+	t |= (bin2bcd(tm->tm_hour) << STM32_RTC_HOUR_SHIFT) & STM32_RTC_HOUR;
+
+	/* Date in BCD format */
+	d = (bin2bcd(tm->tm_mday) << STM32_RTC_DATE_SHIFT) & STM32_RTC_DATE;
+	d |= (bin2bcd(tm->tm_mon) << STM32_RTC_MONTH_SHIFT) & STM32_RTC_MONTH;
+	d |= (bin2bcd(tm->tm_year) << STM32_RTC_YEAR_SHIFT) & STM32_RTC_YEAR;
+	d |= (bin2bcd(tm->tm_wday) << STM32_RTC_WDAY_SHIFT) & STM32_RTC_WDAY;
+
+	return stm32_rtc_set_time(dev, t, d);
+}
+
+static int stm32_rtc_reset(struct udevice *dev)
+{
+	dev_dbg(dev, "Reset DATE\n");
+
+	return stm32_rtc_set_time(dev, 0, 0);
+}
+
+static int stm32_rtc_init(struct udevice *dev)
+{
+	struct stm32_rtc_priv *priv = dev_get_priv(dev);
+	unsigned int prer, pred_a, pred_s, pred_a_max, pred_s_max, cr;
+	unsigned int rate;
+	struct clk clk;
+	int ret;
+	u32 isr = readl(priv->base + STM32_RTC_ISR);
+
+	if (isr & STM32_RTC_ISR_INITS)
+		return  0;
+
+	ret = clk_get_by_index(dev, 1, &clk);
+	if (ret)
+		return ret;
+
+	ret = clk_enable(&clk);
+	if (ret) {
+		clk_free(&clk);
+		return ret;
+	}
+
+	rate = clk_get_rate(&clk);
+
+	/* Find prediv_a and prediv_s to obtain the 1Hz calendar clock */
+	pred_a_max = STM32_RTC_PRER_PRED_A >> STM32_RTC_PRER_PRED_A_SHIFT;
+	pred_s_max = STM32_RTC_PRER_PRED_S >> STM32_RTC_PRER_PRED_S_SHIFT;
+
+	for (pred_a = pred_a_max; pred_a + 1 > 0; pred_a--) {
+		pred_s = (rate / (pred_a + 1)) - 1;
+
+		if (((pred_s + 1) * (pred_a + 1)) == rate)
+			break;
+	}
+
+	/*
+	 * Can't find a 1Hz, so give priority to RTC power consumption
+	 * by choosing the higher possible value for prediv_a
+	 */
+	if (pred_s > pred_s_max || pred_a > pred_a_max) {
+		pred_a = pred_a_max;
+		pred_s = (rate / (pred_a + 1)) - 1;
+	}
+
+	stm32_rtc_unlock(dev);
+
+	ret = stm32_rtc_enter_init_mode(dev);
+	if (ret) {
+		dev_err(dev,
+			"Can't enter in init mode. Prescaler config failed.\n");
+		goto unlock;
+	}
+
+	prer = (pred_s << STM32_RTC_PRER_PRED_S_SHIFT) & STM32_RTC_PRER_PRED_S;
+	prer |= (pred_a << STM32_RTC_PRER_PRED_A_SHIFT) & STM32_RTC_PRER_PRED_A;
+	writel(prer, priv->base + STM32_RTC_PRER);
+
+	/* Force 24h time format */
+	cr = readl(priv->base + STM32_RTC_CR);
+	cr &= ~STM32_RTC_CR_FMT;
+	writel(cr, priv->base + STM32_RTC_CR);
+
+	stm32_rtc_exit_init_mode(dev);
+
+	ret = stm32_rtc_wait_sync(dev);
+
+unlock:
+	stm32_rtc_lock(dev);
+
+	if (ret) {
+		clk_disable(&clk);
+		clk_free(&clk);
+	}
+
+	return ret;
+}
+
+static int stm32_rtc_probe(struct udevice *dev)
+{
+	struct stm32_rtc_priv *priv = dev_get_priv(dev);
+	struct clk clk;
+	int ret;
+
+	priv->base = dev_read_addr(dev);
+	if (priv->base == FDT_ADDR_T_NONE)
+		return -EINVAL;
+
+	ret = clk_get_by_index(dev, 0, &clk);
+	if (ret)
+		return ret;
+
+	ret = clk_enable(&clk);
+	if (ret) {
+		clk_free(&clk);
+		return ret;
+	}
+
+	ret = stm32_rtc_init(dev);
+
+	if (ret) {
+		clk_disable(&clk);
+		clk_free(&clk);
+	}
+
+	return ret;
+}
+
+static const struct rtc_ops stm32_rtc_ops = {
+	.get = stm32_rtc_get,
+	.set = stm32_rtc_set,
+	.reset = stm32_rtc_reset,
+};
+
+static const struct udevice_id stm32_rtc_ids[] = {
+	{ .compatible = "st,stm32mp1-rtc" },
+	{ }
+};
+
+U_BOOT_DRIVER(rtc_stm32) = {
+	.name	= "rtc-stm32",
+	.id	= UCLASS_RTC,
+	.probe	= stm32_rtc_probe,
+	.of_match = stm32_rtc_ids,
+	.ops	= &stm32_rtc_ops,
+	.priv_auto_alloc_size = sizeof(struct stm32_rtc_priv),
+};