[v5,1/2] rtc/fsl: add FTM alarm driver as the wakeup source

diff --git a/drivers/rtc/Kconfig b/drivers/rtc/Kconfig
index 5b9b2eec1435..ac6728ba7895 100644
--- a/drivers/rtc/Kconfig
+++ b/drivers/rtc/Kconfig
@@ -1322,6 +1322,21 @@  config RTC_DRV_IMXDI
 	   This driver can also be built as a module, if so, the module
 	   will be called "rtc-imxdi".
 
+config RTC_DRV_FSL_FTM_ALARM
+	tristate "Freescale FlexTimer alarm timer"
+	depends on ARCH_LAYERSCAPE
+	select FSL_RCPM
+	default y
+	help
+	   For the FlexTimer in LS1012A, LS1021A, LS1028A, LS1043A, LS1046A,
+	   LS1088A, LS208xA, we can use FTM as the wakeup source.
+
+	   Say y here to enable FTM alarm support. The FTM alarm provides
+	   alarm functions for wakeup system from deep sleep.
+
+	   This driver can also be built as a module, if so, the module
+	   will be called "rtc-fsl-ftm-alarm".
+
 config RTC_DRV_MESON
 	tristate "Amlogic Meson RTC"
 	depends on (ARM && ARCH_MESON) || COMPILE_TEST
diff --git a/drivers/rtc/Makefile b/drivers/rtc/Makefile
index 84deeddc8f14..5b1fa1d3a7e8 100644
--- a/drivers/rtc/Makefile
+++ b/drivers/rtc/Makefile
@@ -71,6 +71,7 @@  obj-$(CONFIG_RTC_DRV_EFI)	+= rtc-efi.o
 obj-$(CONFIG_RTC_DRV_EM3027)	+= rtc-em3027.o
 obj-$(CONFIG_RTC_DRV_EP93XX)	+= rtc-ep93xx.o
 obj-$(CONFIG_RTC_DRV_FM3130)	+= rtc-fm3130.o
+obj-$(CONFIG_RTC_DRV_FSL_FTM_ALARM)	+= rtc-fsl-ftm-alarm.o
 obj-$(CONFIG_RTC_DRV_FTRTC010)	+= rtc-ftrtc010.o
 obj-$(CONFIG_RTC_DRV_GENERIC)	+= rtc-generic.o
 obj-$(CONFIG_RTC_DRV_GOLDFISH)	+= rtc-goldfish.o
diff --git a/drivers/rtc/rtc-fsl-ftm-alarm.c b/drivers/rtc/rtc-fsl-ftm-alarm.c
new file mode 100644
index 000000000000..4f7259c2d6a3
--- /dev/null
+++ b/drivers/rtc/rtc-fsl-ftm-alarm.c
@@ -0,0 +1,336 @@ 
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * Freescale FlexTimer Module (FTM) alarm device driver.
+ *
+ * Copyright 2014 Freescale Semiconductor, Inc.
+ * Copyright 2019 NXP
+ *
+ */
+
+#include <linux/device.h>
+#include <linux/err.h>
+#include <linux/interrupt.h>
+#include <linux/io.h>
+#include <linux/of_address.h>
+#include <linux/of_irq.h>
+#include <linux/platform_device.h>
+#include <linux/of.h>
+#include <linux/of_device.h>
+#include <linux/module.h>
+#include <linux/fsl/ftm.h>
+#include <linux/rtc.h>
+#include <linux/time.h>
+
+#define FTM_SC_CLK(c)		((c) << FTM_SC_CLK_MASK_SHIFT)
+
+/*
+ * Select Fixed frequency clock (32KHz) as clock source
+ * of FlexTimer Module
+ */
+#define FTM_SC_CLKS_FIXED_FREQ	0x02
+#define FIXED_FREQ_CLK		32000
+
+/* Select 128 (2^7) as divider factor */
+#define MAX_FREQ_DIV		(1 << FTM_SC_PS_MASK)
+
+/* Maximum counter value in FlexTimer's CNT registers */
+#define MAX_COUNT_VAL		0xffff
+
+struct ftm_rtc {
+	struct rtc_device *rtc_dev;
+	void __iomem *base;
+	bool big_endian;
+	u32 alarm_freq;
+};
+
+static inline u32 rtc_readl(struct ftm_rtc *dev, u32 reg)
+{
+	if (dev->big_endian)
+		return ioread32be(dev->base + reg);
+	else
+		return ioread32(dev->base + reg);
+}
+
+static inline void rtc_writel(struct ftm_rtc *dev, u32 reg, u32 val)
+{
+	if (dev->big_endian)
+		iowrite32be(val, dev->base + reg);
+	else
+		iowrite32(val, dev->base + reg);
+}
+
+static inline void ftm_counter_enable(struct ftm_rtc *rtc)
+{
+	u32 val;
+
+	/* select and enable counter clock source */
+	val = rtc_readl(rtc, FTM_SC);
+	val &= ~(FTM_SC_PS_MASK | FTM_SC_CLK_MASK);
+	val |= (FTM_SC_PS_MASK | FTM_SC_CLK(FTM_SC_CLKS_FIXED_FREQ));
+	rtc_writel(rtc, FTM_SC, val);
+}
+
+static inline void ftm_counter_disable(struct ftm_rtc *rtc)
+{
+	u32 val;
+
+	/* disable counter clock source */
+	val = rtc_readl(rtc, FTM_SC);
+	val &= ~(FTM_SC_PS_MASK | FTM_SC_CLK_MASK);
+	rtc_writel(rtc, FTM_SC, val);
+}
+
+static inline void ftm_irq_acknowledge(struct ftm_rtc *rtc)
+{
+	unsigned int timeout = 100;
+
+	/*
+	 *Fix errata A-007728 for flextimer
+	 *	If the FTM counter reaches the FTM_MOD value between
+	 *	the reading of the TOF bit and the writing of 0 to
+	 *	the TOF bit, the process of clearing the TOF bit
+	 *	does not work as expected when FTMx_CONF[NUMTOF] != 0
+	 *	and the current TOF count is less than FTMx_CONF[NUMTOF].
+	 *	If the above condition is met, the TOF bit remains set.
+	 *	If the TOF interrupt is enabled (FTMx_SC[TOIE] = 1),the
+	 *	TOF interrupt also remains asserted.
+	 *
+	 *	Above is the errata discription
+	 *
+	 *	In one word: software clearing TOF bit not works when
+	 *	FTMx_CONF[NUMTOF] was seted as nonzero and FTM counter
+	 *	reaches the FTM_MOD value.
+	 *
+	 *	The workaround is clearing TOF bit until it works
+	 *	(FTM counter doesn't always reache the FTM_MOD anyway),
+	 *	which may cost some cycles.
+	 */
+	while ((FTM_SC_TOF & rtc_readl(rtc, FTM_SC)) && timeout--)
+		rtc_writel(rtc, FTM_SC, rtc_readl(rtc, FTM_SC) & (~FTM_SC_TOF));
+}
+
+static inline void ftm_irq_enable(struct ftm_rtc *rtc)
+{
+	u32 val;
+
+	val = rtc_readl(rtc, FTM_SC);
+	val |= FTM_SC_TOIE;
+	rtc_writel(rtc, FTM_SC, val);
+}
+
+static inline void ftm_irq_disable(struct ftm_rtc *rtc)
+{
+	u32 val;
+
+	val = rtc_readl(rtc, FTM_SC);
+	val &= ~FTM_SC_TOIE;
+	rtc_writel(rtc, FTM_SC, val);
+}
+
+static inline void ftm_reset_counter(struct ftm_rtc *rtc)
+{
+	/*
+	 * The CNT register contains the FTM counter value.
+	 * Reset clears the CNT register. Writing any value to COUNT
+	 * updates the counter with its initial value, CNTIN.
+	 */
+	rtc_writel(rtc, FTM_CNT, 0x00);
+}
+
+static void ftm_clean_alarm(struct ftm_rtc *rtc)
+{
+	ftm_counter_disable(rtc);
+
+	rtc_writel(rtc, FTM_CNTIN, 0x00);
+	rtc_writel(rtc, FTM_MOD, ~0U);
+
+	ftm_reset_counter(rtc);
+}
+
+static irqreturn_t ftm_rtc_alarm_interrupt(int irq, void *dev)
+{
+	struct ftm_rtc *rtc = dev;
+
+	ftm_irq_acknowledge(rtc);
+	ftm_irq_disable(rtc);
+	ftm_clean_alarm(rtc);
+
+	return IRQ_HANDLED;
+}
+
+static int ftm_rtc_alarm_irq_enable(struct device *dev,
+		unsigned int enabled)
+{
+	struct ftm_rtc *rtc = dev_get_drvdata(dev);
+
+	if (enabled)
+		ftm_irq_enable(rtc);
+	else
+		ftm_irq_disable(rtc);
+
+	return 0;
+}
+
+/*
+ * Note:
+ *	The function is not really getting time from the RTC
+ *	since FlexTimer is not a RTC device, but we need to
+ *	get time to setup alarm, so we are using system time
+ *	for now.
+ */
+static int ftm_rtc_read_time(struct device *dev, struct rtc_time *tm)
+{
+	struct timespec64 ts64;
+
+	ktime_get_real_ts64(&ts64);
+	rtc_time_to_tm(ts64.tv_sec, tm);
+
+	return 0;
+}
+
+static int ftm_rtc_read_alarm(struct device *dev, struct rtc_wkalrm *alm)
+{
+	return 0;
+}
+
+/*
+ * 1. Select fixed frequency clock (32KHz) as clock source;
+ * 2. Select 128 (2^7) as divider factor;
+ * So clock is 250 Hz (32KHz/128).
+ *
+ * 3. FlexTimer's CNT register is a 32bit register,
+ * but the register's 16 bit as counter value,it's other 16 bit
+ * is reserved.So minimum counter value is 0x0,maximum counter
+ * value is 0xffff.
+ * So max alarm value is 262 (65536 / 250) seconds
+ */
+static int ftm_rtc_set_alarm(struct device *dev, struct rtc_wkalrm *alm)
+{
+	struct rtc_time tm;
+	unsigned long now, alm_time, cycle;
+	struct ftm_rtc *rtc = dev_get_drvdata(dev);
+
+	ftm_rtc_read_time(dev, &tm);
+	rtc_tm_to_time(&tm, &now);
+	rtc_tm_to_time(&alm->time, &alm_time);
+
+	ftm_clean_alarm(rtc);
+	cycle = (alm_time - now) * rtc->alarm_freq;
+	if (cycle > MAX_COUNT_VAL) {
+		pr_err("Out of alarm range {0~262} seconds.\n");
+		return -ERANGE;
+	}
+
+	ftm_irq_disable(rtc);
+
+	/*
+	 * The counter increments until the value of MOD is reached,
+	 * at which point the counter is reloaded with the value of CNTIN.
+	 * The TOF (the overflow flag) bit is set when the FTM counter
+	 * changes from MOD to CNTIN. So we should using the cycle - 1.
+	 */
+	rtc_writel(rtc, FTM_MOD, cycle - 1);
+
+	ftm_counter_enable(rtc);
+	ftm_irq_enable(rtc);
+
+	return 0;
+
+}
+
+static const struct rtc_class_ops ftm_rtc_ops = {
+	.read_time		= ftm_rtc_read_time,
+	.read_alarm		= ftm_rtc_read_alarm,
+	.set_alarm		= ftm_rtc_set_alarm,
+	.alarm_irq_enable	= ftm_rtc_alarm_irq_enable,
+};
+
+static int ftm_rtc_probe(struct platform_device *pdev)
+{
+	struct device_node *np = pdev->dev.of_node;
+	struct resource *r;
+	int irq;
+	int ret;
+	struct ftm_rtc *rtc;
+
+	rtc = devm_kzalloc(&pdev->dev, sizeof(*rtc), GFP_KERNEL);
+	if (unlikely(!rtc)) {
+		dev_err(&pdev->dev, "cannot alloc memery for rtc\n");
+		return -ENOMEM;
+	}
+
+	platform_set_drvdata(pdev, rtc);
+
+	rtc->rtc_dev = devm_rtc_allocate_device(&pdev->dev);
+	if (IS_ERR(rtc->rtc_dev))
+		return PTR_ERR(rtc->rtc_dev);
+
+	r = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+	if (!r) {
+		dev_err(&pdev->dev, "cannot get resource for rtc\n");
+		return -ENODEV;
+	}
+
+	rtc->base = devm_ioremap_resource(&pdev->dev, r);
+	if (IS_ERR(rtc->base)) {
+		dev_err(&pdev->dev, "cannot ioremap resource for rtc\n");
+		return PTR_ERR(rtc->base);
+	}
+
+	irq = irq_of_parse_and_map(np, 0);
+	if (irq <= 0) {
+		dev_err(&pdev->dev, "unable to get IRQ from DT, %d\n", irq);
+		return -EINVAL;
+	}
+
+	ret = devm_request_irq(&pdev->dev, irq, ftm_rtc_alarm_interrupt,
+			       IRQF_NO_SUSPEND, dev_name(&pdev->dev), rtc);
+	if (ret < 0) {
+		dev_err(&pdev->dev, "failed to request irq\n");
+		return ret;
+	}
+
+	rtc->big_endian = of_property_read_bool(np, "big-endian");
+	rtc->alarm_freq = (u32)FIXED_FREQ_CLK / (u32)MAX_FREQ_DIV;
+	rtc->rtc_dev->ops = &ftm_rtc_ops;
+
+	device_init_wakeup(&pdev->dev, true);
+
+	ret = rtc_register_device(rtc->rtc_dev);
+	if (ret) {
+		dev_err(&pdev->dev, "can't register rtc device\n");
+		return ret;
+	}
+
+	return 0;
+}
+
+static const struct of_device_id ftm_rtc_match[] = {
+	{ .compatible = "fsl,ls1012a-ftm-alarm", },
+	{ .compatible = "fsl,ls1021a-ftm-alarm", },
+	{ .compatible = "fsl,ls1043a-ftm-alarm", },
+	{ .compatible = "fsl,ls1046a-ftm-alarm", },
+	{ .compatible = "fsl,ls1088a-ftm-alarm", },
+	{ .compatible = "fsl,ls208xa-ftm-alarm", },
+	{ .compatible = "fsl,ls1028a-ftm-alarm", },
+	{ },
+};
+
+static struct platform_driver ftm_rtc_driver = {
+	.probe		= ftm_rtc_probe,
+	.driver		= {
+		.name	= "ftm-alarm",
+		.of_match_table = ftm_rtc_match,
+	},
+};
+
+static int __init ftm_alarm_init(void)
+{
+	return platform_driver_register(&ftm_rtc_driver);
+}
+
+device_initcall(ftm_alarm_init);
+
+MODULE_DESCRIPTION("NXP/Freescale FlexTimer alarm driver");
+MODULE_AUTHOR("Biwen Li <biwen.li@nxp.com>");
+MODULE_LICENSE("GPL");