Message-ID: <20241126114940.421143-3-ciprianmarian.costea@oss.nxp.com>
Date: Tue, 26 Nov 2024 13:49:38 +0200
From: Ciprian Costea <ciprianmarian.costea@....nxp.com>
To: Alexandre Belloni <alexandre.belloni@...tlin.com>,
	Rob Herring <robh@...nel.org>,
	Krzysztof Kozlowski <krzk+dt@...nel.org>,
	Conor Dooley <conor+dt@...nel.org>,
	Catalin Marinas <catalin.marinas@....com>,
	Will Deacon <will@...nel.org>
Cc: linux-rtc@...r.kernel.org,
	devicetree@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	linux-arm-kernel@...ts.infradead.org,
	imx@...ts.linux.dev,
	NXP S32 Linux <s32@....com>,
	Christophe Lizzi <clizzi@...hat.com>,
	Alberto Ruiz <aruizrui@...hat.com>,
	Enric Balletbo <eballetb@...hat.com>,
	Ciprian Marian Costea <ciprianmarian.costea@....nxp.com>,
	Bogdan Hamciuc <bogdan.hamciuc@....com>,
	Ghennadi Procopciuc <Ghennadi.Procopciuc@....com>
Subject: [PATCH v5 2/4] rtc: s32g: add NXP S32G2/S32G3 SoC support

From: Ciprian Marian Costea <ciprianmarian.costea@....nxp.com>

Add a RTC driver for NXP S32G2/S32G3 SoCs.

RTC tracks clock time during system suspend. It can be a wakeup source
for the S32G2/S32G3 SoC based boards.

The RTC module from S32G2/S32G3 is not battery-powered and it is not kept
alive during system reset.

Co-developed-by: Bogdan Hamciuc <bogdan.hamciuc@....com>
Signed-off-by: Bogdan Hamciuc <bogdan.hamciuc@....com>
Co-developed-by: Ghennadi Procopciuc <Ghennadi.Procopciuc@....com>
Signed-off-by: Ghennadi Procopciuc <Ghennadi.Procopciuc@....com>
Signed-off-by: Ciprian Marian Costea <ciprianmarian.costea@....nxp.com>
---
 drivers/rtc/Kconfig    |  11 +
 drivers/rtc/Makefile   |   1 +
 drivers/rtc/rtc-s32g.c | 554 +++++++++++++++++++++++++++++++++++++++++
 3 files changed, 566 insertions(+)
 create mode 100644 drivers/rtc/rtc-s32g.c

diff --git a/drivers/rtc/Kconfig b/drivers/rtc/Kconfig
index e87c3d74565c..18fc3577f6cd 100644
--- a/drivers/rtc/Kconfig
+++ b/drivers/rtc/Kconfig
@@ -2054,4 +2054,15 @@ config RTC_DRV_SSD202D
 	  This driver can also be built as a module, if so, the module
 	  will be called "rtc-ssd20xd".
 
+config RTC_DRV_S32G
+	tristate "RTC driver for S32G2/S32G3 SoCs"
+	depends on ARCH_S32 || COMPILE_TEST
+	depends on COMMON_CLK
+	help
+	  Say yes to enable RTC driver for platforms based on the
+	  S32G2/S32G3 SoC family.
+
+	  This RTC module can be used as a wakeup source.
+	  Please note that it is not battery-powered.
+
 endif # RTC_CLASS
diff --git a/drivers/rtc/Makefile b/drivers/rtc/Makefile
index 8ee79cb18322..a63d010a753c 100644
--- a/drivers/rtc/Makefile
+++ b/drivers/rtc/Makefile
@@ -158,6 +158,7 @@ obj-$(CONFIG_RTC_DRV_RX8025)	+= rtc-rx8025.o
 obj-$(CONFIG_RTC_DRV_RX8111)	+= rtc-rx8111.o
 obj-$(CONFIG_RTC_DRV_RX8581)	+= rtc-rx8581.o
 obj-$(CONFIG_RTC_DRV_RZN1)	+= rtc-rzn1.o
+obj-$(CONFIG_RTC_DRV_S32G)	+= rtc-s32g.o
 obj-$(CONFIG_RTC_DRV_S35390A)	+= rtc-s35390a.o
 obj-$(CONFIG_RTC_DRV_S3C)	+= rtc-s3c.o
 obj-$(CONFIG_RTC_DRV_S5M)	+= rtc-s5m.o
diff --git a/drivers/rtc/rtc-s32g.c b/drivers/rtc/rtc-s32g.c
new file mode 100644
index 000000000000..ad78423783da
--- /dev/null
+++ b/drivers/rtc/rtc-s32g.c
@@ -0,0 +1,554 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * Copyright 2024 NXP
+ */
+
+#include <linux/clk.h>
+#include <linux/clk-provider.h>
+#include <linux/err.h>
+#include <linux/iopoll.h>
+#include <linux/math64.h>
+#include <linux/of_irq.h>
+#include <linux/platform_device.h>
+#include <linux/rtc.h>
+
+#define RTCC_OFFSET	0x4ul
+#define RTCS_OFFSET	0x8ul
+#define RTCCNT_OFFSET	0xCul
+#define APIVAL_OFFSET	0x10ul
+#define RTCVAL_OFFSET	0x14ul
+
+/* RTCC fields */
+#define RTCC_CNTEN				BIT(31)
+#define RTCC_RTCIE_SHIFT		30
+#define RTCC_RTCIE				BIT(RTCC_RTCIE_SHIFT)
+#define RTCC_APIEN				BIT(15)
+#define RTCC_APIIE				BIT(14)
+#define RTCC_CLKSEL_OFFSET		12
+#define RTCC_CLKSEL_MASK		GENMASK(13, 12)
+#define RTCC_CLKSEL(n)			(((n) << 12) & RTCC_CLKSEL_MASK)
+#define RTCC_DIV512EN			BIT(11)
+#define RTCC_DIV32EN			BIT(10)
+
+/* RTCS fields */
+#define RTCS_RTCF		BIT(29)
+#define RTCS_INV_RTC		BIT(18)
+#define RTCS_APIF		BIT(13)
+
+#define RTCCNT_MAX_VAL		GENMASK(31, 0)
+#define RTC_SYNCH_TIMEOUT	(100 * USEC_PER_MSEC)
+
+#define RTC_CLK_MUX_SIZE	4
+
+/*
+ * S32G2 and S32G3 SoCs have RTC clock source 1 reserved and
+ * should not be used.
+ */
+#define RTC_QUIRK_SRC1_RESERVED			BIT(2)
+
+enum {
+	RTC_CLK_SRC0,
+	RTC_CLK_SRC1,
+	RTC_CLK_SRC2,
+	RTC_CLK_SRC3
+};
+
+enum {
+	DIV1 = 1,
+	DIV32 = 32,
+	DIV512 = 512,
+	DIV512_32 = 16384
+};
+
+static const char *rtc_clk_src[RTC_CLK_MUX_SIZE] = {
+	"source0",
+	"source1",
+	"source2",
+	"source3"
+};
+
+struct rtc_time_base {
+	s64 sec;
+	u64 cycles;
+	struct rtc_time tm;
+};
+
+struct rtc_priv {
+	struct rtc_device *rdev;
+	void __iomem *rtc_base;
+	struct clk *ipg;
+	struct clk *clk_src;
+	const struct rtc_soc_data *rtc_data;
+	struct rtc_time_base base;
+	u64 rtc_hz;
+	int dt_irq_id;
+	int clk_src_idx;
+};
+
+struct rtc_soc_data {
+	u32 clk_div;
+	u32 quirks;
+};
+
+static const struct rtc_soc_data rtc_s32g2_data = {
+	.clk_div = DIV512,
+	.quirks = RTC_QUIRK_SRC1_RESERVED,
+};
+
+static int is_src1_reserved(struct rtc_priv *priv)
+{
+	return priv->rtc_data->quirks & RTC_QUIRK_SRC1_RESERVED;
+}
+
+static u64 cycles_to_sec(u64 hz, u64 cycles)
+{
+	return div_u64(cycles, hz);
+}
+
+/**
+ * Convert a number of seconds to a value suitable for RTCVAL in our clock's
+ * current configuration.
+ * @rtcval: The value to go into RTCVAL[RTCVAL]
+ * Returns: 0 for success, -EINVAL if @seconds push the counter past the
+ *          32bit register range
+ */
+static int sec_to_rtcval(const struct rtc_priv *priv,
+			 unsigned long seconds, u32 *rtcval)
+{
+	u32 delta_cnt;
+
+	if (!seconds || seconds > cycles_to_sec(priv->rtc_hz, RTCCNT_MAX_VAL))
+		return -EINVAL;
+
+	/*
+	 * RTCCNT is read-only; we must return a value relative to the
+	 * current value of the counter (and hope we don't linger around
+	 * too much before we get to enable the interrupt)
+	 */
+	delta_cnt = seconds * priv->rtc_hz;
+	*rtcval = delta_cnt + ioread32(priv->rtc_base + RTCCNT_OFFSET);
+
+	return 0;
+}
+
+static irqreturn_t s32g_rtc_handler(int irq, void *dev)
+{
+	struct rtc_priv *priv = platform_get_drvdata(dev);
+	u32 status;
+
+	status = ioread32(priv->rtc_base + RTCS_OFFSET);
+
+	if (status & RTCS_RTCF) {
+		iowrite32(0x0, priv->rtc_base + RTCVAL_OFFSET);
+		rtc_update_irq(priv->rdev, 1, RTC_AF);
+	}
+
+	if (status & RTCS_APIF)
+		rtc_update_irq(priv->rdev, 1, RTC_PF);
+
+	iowrite32(status, priv->rtc_base + RTCS_OFFSET);
+
+	return IRQ_HANDLED;
+}
+
+static s64 s32g_rtc_get_time_or_alrm(struct rtc_priv *priv,
+				     u32 offset)
+{
+	u32 counter;
+
+	counter = ioread32(priv->rtc_base + offset);
+
+	if (counter < priv->base.cycles)
+		return -EINVAL;
+
+	counter -= priv->base.cycles;
+
+	return priv->base.sec + cycles_to_sec(priv->rtc_hz, counter);
+}
+
+static int s32g_rtc_read_time(struct device *dev,
+			      struct rtc_time *tm)
+{
+	struct rtc_priv *priv = dev_get_drvdata(dev);
+	s64 sec;
+
+	sec = s32g_rtc_get_time_or_alrm(priv, RTCCNT_OFFSET);
+	if (sec < 0)
+		return -EINVAL;
+
+	rtc_time64_to_tm(sec, tm);
+
+	return 0;
+}
+
+static int s32g_rtc_read_alarm(struct device *dev, struct rtc_wkalrm *alrm)
+{
+	struct rtc_priv *priv = dev_get_drvdata(dev);
+	u32 rtcc, rtccnt, rtcval;
+	s64 sec;
+
+	sec = s32g_rtc_get_time_or_alrm(priv, RTCVAL_OFFSET);
+	if (sec < 0)
+		return -EINVAL;
+
+	rtc_time64_to_tm(sec, &alrm->time);
+
+	rtcc = ioread32(priv->rtc_base + RTCC_OFFSET);
+	alrm->enabled = sec && (rtcc & RTCC_RTCIE);
+
+	alrm->pending = 0;
+	if (alrm->enabled) {
+		rtccnt = ioread32(priv->rtc_base + RTCCNT_OFFSET);
+		rtcval = ioread32(priv->rtc_base + RTCVAL_OFFSET);
+
+		if (rtccnt < rtcval)
+			alrm->pending = 1;
+	}
+
+	return 0;
+}
+
+static int s32g_rtc_alarm_irq_enable(struct device *dev, unsigned int enabled)
+{
+	struct rtc_priv *priv = dev_get_drvdata(dev);
+	u32 rtcc;
+
+	if (!priv->dt_irq_id)
+		return -EIO;
+
+	rtcc = ioread32(priv->rtc_base + RTCC_OFFSET);
+	if (enabled)
+		rtcc |= RTCC_RTCIE;
+
+	iowrite32(rtcc, priv->rtc_base + RTCC_OFFSET);
+
+	return 0;
+}
+
+static int s32g_rtc_set_alarm(struct device *dev, struct rtc_wkalrm *alrm)
+{
+	struct rtc_priv *priv = dev_get_drvdata(dev);
+	struct rtc_time time_crt;
+	long long t_crt, t_alrm;
+	u32 rtcval, rtcs;
+	int ret = 0;
+
+	iowrite32(0x0, priv->rtc_base + RTCVAL_OFFSET);
+
+	t_alrm = rtc_tm_to_time64(&alrm->time);
+
+	/*
+	 * Assuming the alarm is being set relative to the same time
+	 * returned by our s32g_rtc_read_time callback
+	 */
+	ret = s32g_rtc_read_time(dev, &time_crt);
+	if (ret)
+		return ret;
+
+	t_crt = rtc_tm_to_time64(&time_crt);
+	ret = sec_to_rtcval(priv, t_alrm - t_crt, &rtcval);
+	if (ret) {
+		dev_warn(dev, "Alarm is set too far in the future\n");
+		return -ERANGE;
+	}
+
+	ret = read_poll_timeout(ioread32, rtcs, !(rtcs & RTCS_INV_RTC),
+				0, RTC_SYNCH_TIMEOUT, false, priv->rtc_base + RTCS_OFFSET);
+	if (ret)
+		return ret;
+
+	iowrite32(rtcval, priv->rtc_base + RTCVAL_OFFSET);
+
+	return 0;
+}
+
+static int s32g_rtc_set_time(struct device *dev,
+			     struct rtc_time *time)
+{
+	struct rtc_priv *priv = dev_get_drvdata(dev);
+
+	priv->base.cycles = ioread32(priv->rtc_base + RTCCNT_OFFSET);
+	priv->base.sec = rtc_tm_to_time64(time);
+
+	return 0;
+}
+
+/*
+ * Disable the 32-bit free running counter.
+ * This allows Clock Source and Divisors selection
+ * to be performed without causing synchronization issues.
+ */
+static void s32g_rtc_disable(struct rtc_priv *priv)
+{
+	u32 rtcc = ioread32(priv->rtc_base + RTCC_OFFSET);
+
+	rtcc &= ~RTCC_CNTEN;
+	iowrite32(rtcc, priv->rtc_base + RTCC_OFFSET);
+}
+
+static void s32g_rtc_enable(struct rtc_priv *priv)
+{
+	u32 rtcc = ioread32(priv->rtc_base + RTCC_OFFSET);
+
+	rtcc |= RTCC_CNTEN;
+	iowrite32(rtcc, priv->rtc_base + RTCC_OFFSET);
+}
+
+static int rtc_clk_src_setup(struct rtc_priv *priv)
+{
+	u32 rtcc = 0;
+
+	switch (priv->clk_src_idx) {
+	case RTC_CLK_SRC0:
+		rtcc |= RTCC_CLKSEL(RTC_CLK_SRC0);
+		break;
+	case RTC_CLK_SRC1:
+		if (is_src1_reserved(priv))
+			return -EOPNOTSUPP;
+		rtcc |= RTCC_CLKSEL(RTC_CLK_SRC1);
+		break;
+	case RTC_CLK_SRC2:
+		rtcc |= RTCC_CLKSEL(RTC_CLK_SRC2);
+		break;
+	case RTC_CLK_SRC3:
+		rtcc |= RTCC_CLKSEL(RTC_CLK_SRC3);
+		break;
+	default:
+		return -EINVAL;
+	}
+
+	switch (priv->rtc_data->clk_div) {
+	case DIV512_32:
+		rtcc |= RTCC_DIV512EN;
+		rtcc |= RTCC_DIV32EN;
+		break;
+	case DIV512:
+		rtcc |= RTCC_DIV512EN;
+		break;
+	case DIV32:
+		rtcc |= RTCC_DIV32EN;
+		break;
+	case DIV1:
+		break;
+	default:
+		return -EINVAL;
+	}
+
+	rtcc |= RTCC_RTCIE;
+	/*
+	 * Make sure the CNTEN is 0 before we configure
+	 * the clock source and dividers.
+	 */
+	s32g_rtc_disable(priv);
+	iowrite32(rtcc, priv->rtc_base + RTCC_OFFSET);
+	s32g_rtc_enable(priv);
+
+	return 0;
+}
+
+static const struct rtc_class_ops rtc_ops = {
+	.read_time = s32g_rtc_read_time,
+	.set_time = s32g_rtc_set_time,
+	.read_alarm = s32g_rtc_read_alarm,
+	.set_alarm = s32g_rtc_set_alarm,
+	.alarm_irq_enable = s32g_rtc_alarm_irq_enable,
+};
+
+static int rtc_clk_dts_setup(struct rtc_priv *priv,
+			     struct device *dev)
+{
+	int i;
+
+	priv->ipg = devm_clk_get_enabled(dev, "ipg");
+	if (IS_ERR(priv->ipg))
+		return dev_err_probe(dev, PTR_ERR(priv->ipg),
+				"Failed to get 'ipg' clock\n");
+
+	for (i = 0; i < RTC_CLK_MUX_SIZE; i++) {
+		priv->clk_src = devm_clk_get_enabled(dev, rtc_clk_src[i]);
+		if (!IS_ERR(priv->clk_src)) {
+			priv->clk_src_idx = i;
+			break;
+		}
+	}
+
+	if (IS_ERR(priv->clk_src))
+		return dev_err_probe(dev, PTR_ERR(priv->clk_src),
+				"Failed to get rtc module clock source\n");
+
+	return 0;
+}
+
+static int s32g_rtc_probe(struct platform_device *pdev)
+{
+	struct device *dev = &pdev->dev;
+	struct rtc_priv *priv;
+	int ret = 0;
+
+	priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL);
+	if (!priv)
+		return -ENOMEM;
+
+	priv->rtc_data = of_device_get_match_data(dev);
+	if (!priv->rtc_data)
+		return -ENODEV;
+
+	priv->rtc_base = devm_platform_ioremap_resource(pdev, 0);
+	if (IS_ERR(priv->rtc_base))
+		return PTR_ERR(priv->rtc_base);
+
+	device_init_wakeup(dev, true);
+
+	ret = rtc_clk_dts_setup(priv, dev);
+	if (ret)
+		return ret;
+
+	priv->rdev = devm_rtc_allocate_device(dev);
+	if (IS_ERR(priv->rdev))
+		return PTR_ERR(priv->rdev);
+
+	ret = rtc_clk_src_setup(priv);
+	if (ret)
+		return ret;
+
+	priv->rtc_hz = clk_get_rate(priv->clk_src);
+	if (!priv->rtc_hz)
+		return dev_err_probe(dev, -EINVAL, "Failed to get RTC frequency\n");
+
+	priv->rtc_hz /= priv->rtc_data->clk_div;
+
+	platform_set_drvdata(pdev, priv);
+	priv->rdev->ops = &rtc_ops;
+
+	priv->dt_irq_id = platform_get_irq(pdev, 0);
+	if (priv->dt_irq_id < 0)
+		return priv->dt_irq_id;
+
+	ret = devm_request_irq(dev, priv->dt_irq_id,
+			       s32g_rtc_handler, 0, dev_name(dev), pdev);
+	if (ret) {
+		dev_err(dev, "Request interrupt %d failed, error: %d\n",
+			priv->dt_irq_id, ret);
+		goto disable_rtc;
+	}
+
+	ret = devm_rtc_register_device(priv->rdev);
+	if (ret)
+		goto disable_rtc;
+
+	return 0;
+
+disable_rtc:
+	s32g_rtc_disable(priv);
+	return ret;
+}
+
+static void enable_api_irq(struct device *dev, unsigned int enabled)
+{
+	struct rtc_priv *priv = dev_get_drvdata(dev);
+	u32 api_irq = RTCC_APIEN | RTCC_APIIE;
+	u32 rtcc;
+
+	rtcc = ioread32(priv->rtc_base + RTCC_OFFSET);
+	if (enabled)
+		rtcc |= api_irq;
+	else
+		rtcc &= ~api_irq;
+	iowrite32(rtcc, priv->rtc_base + RTCC_OFFSET);
+}
+
+static int s32g_rtc_suspend(struct device *dev)
+{
+	struct rtc_priv *init_priv = dev_get_drvdata(dev);
+	struct rtc_priv priv;
+	long long base_sec;
+	u32 rtcval, rtccnt;
+	int ret = 0;
+	u32 sec;
+
+	if (!device_may_wakeup(dev))
+		return 0;
+
+	/* Save last known timestamp */
+	ret = s32g_rtc_read_time(dev, &init_priv->base.tm);
+	if (ret)
+		return ret;
+
+	/*
+	 * Use a local copy of the RTC control block to
+	 * avoid restoring it on resume path.
+	 */
+	memcpy(&priv, init_priv, sizeof(priv));
+
+	rtccnt = ioread32(init_priv->rtc_base + RTCCNT_OFFSET);
+	rtcval = ioread32(init_priv->rtc_base + RTCVAL_OFFSET);
+	sec = cycles_to_sec(init_priv->rtc_hz, rtcval - rtccnt);
+
+	/* Adjust for the number of seconds we'll be asleep */
+	base_sec = rtc_tm_to_time64(&init_priv->base.tm);
+	base_sec += sec;
+	rtc_time64_to_tm(base_sec, &init_priv->base.tm);
+
+	/* Reset RTC to prevent overflow.
+	 * RTCCNT (RTC Counter) cannot be individually reset
+	 * since it is RO (read-only).
+	 */
+	s32g_rtc_disable(&priv);
+	s32g_rtc_enable(&priv);
+
+	ret = sec_to_rtcval(&priv, sec, &rtcval);
+	if (ret) {
+		dev_warn(dev, "Alarm is too far in the future\n");
+		return -ERANGE;
+	}
+
+	enable_api_irq(dev, 1);
+	iowrite32(rtcval, priv.rtc_base + APIVAL_OFFSET);
+	iowrite32(0, priv.rtc_base + RTCVAL_OFFSET);
+
+	return ret;
+}
+
+static int s32g_rtc_resume(struct device *dev)
+{
+	struct rtc_priv *priv = dev_get_drvdata(dev);
+	int ret;
+
+	if (!device_may_wakeup(dev))
+		return 0;
+
+	/* Disable wake-up interrupts */
+	enable_api_irq(dev, 0);
+
+	ret = rtc_clk_src_setup(priv);
+	if (ret)
+		return ret;
+
+	/*
+	 * Now RTCCNT has just been reset, and is out of sync with priv->base;
+	 * reapply the saved time settings.
+	 */
+	return s32g_rtc_set_time(dev, &priv->base.tm);
+}
+
+static const struct of_device_id rtc_dt_ids[] = {
+	{ .compatible = "nxp,s32g2-rtc", .data = &rtc_s32g2_data},
+	{ /* sentinel */ },
+};
+
+static DEFINE_SIMPLE_DEV_PM_OPS(s32g_rtc_pm_ops,
+			 s32g_rtc_suspend, s32g_rtc_resume);
+
+static struct platform_driver s32g_rtc_driver = {
+	.driver		= {
+		.name			= "s32g-rtc",
+		.pm				= pm_sleep_ptr(&s32g_rtc_pm_ops),
+		.of_match_table = rtc_dt_ids,
+	},
+	.probe		= s32g_rtc_probe,
+};
+module_platform_driver(s32g_rtc_driver);
+
+MODULE_AUTHOR("NXP");
+MODULE_DESCRIPTION("NXP RTC driver for S32G2/S32G3");
+MODULE_LICENSE("GPL");
-- 
2.45.2

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