From 7cb47848f8a10aed6e050c0ea483b4bb5eaa62a4 Mon Sep 17 00:00:00 2001
From: Xingyu Wu <xingyu.wu@starfivetech.com>
Date: Thu, 19 Oct 2023 13:35:00 +0800
Subject: [PATCH 003/116] clocksource: Add JH7110 timer driver

Add timer driver for the StarFive JH7110 SoC.

Signed-off-by: Xingyu Wu <xingyu.wu@starfivetech.com>
---
 drivers/clocksource/Kconfig        |  11 +
 drivers/clocksource/Makefile       |   1 +
 drivers/clocksource/timer-jh7110.c | 380 +++++++++++++++++++++++++++++
 3 files changed, 392 insertions(+)
 create mode 100644 drivers/clocksource/timer-jh7110.c

--- a/drivers/clocksource/Kconfig
+++ b/drivers/clocksource/Kconfig
@@ -642,6 +642,17 @@ config RISCV_TIMER
 	  is accessed via both the SBI and the rdcycle instruction.  This is
 	  required for all RISC-V systems.
 
+config STARFIVE_JH7110_TIMER
+	bool "Timer for the STARFIVE JH7110 SoC"
+	depends on ARCH_STARFIVE || COMPILE_TEST
+	select TIMER_OF
+	select CLKSRC_MMIO
+	default ARCH_STARFIVE
+	help
+	  This enables the timer for StarFive JH7110 SoC. On RISC-V platform,
+	  the system has started RISCV_TIMER, but you can also use this timer
+	  which can provide four channels to do a lot more things on JH7110 SoC.
+
 config CLINT_TIMER
 	bool "CLINT Timer for the RISC-V platform" if COMPILE_TEST
 	depends on GENERIC_SCHED_CLOCK && RISCV
--- a/drivers/clocksource/Makefile
+++ b/drivers/clocksource/Makefile
@@ -80,6 +80,7 @@ obj-$(CONFIG_INGENIC_TIMER)		+= ingenic-
 obj-$(CONFIG_CLKSRC_ST_LPC)		+= clksrc_st_lpc.o
 obj-$(CONFIG_X86_NUMACHIP)		+= numachip.o
 obj-$(CONFIG_RISCV_TIMER)		+= timer-riscv.o
+obj-$(CONFIG_STARFIVE_JH7110_TIMER)	+= timer-jh7110.o
 obj-$(CONFIG_CLINT_TIMER)		+= timer-clint.o
 obj-$(CONFIG_CSKY_MP_TIMER)		+= timer-mp-csky.o
 obj-$(CONFIG_GX6605S_TIMER)		+= timer-gx6605s.o
--- /dev/null
+++ b/drivers/clocksource/timer-jh7110.c
@@ -0,0 +1,380 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Starfive JH7110 Timer driver
+ *
+ * Copyright (C) 2022-2023 StarFive Technology Co., Ltd.
+ *
+ * Author:
+ * Xingyu Wu <xingyu.wu@starfivetech.com>
+ * Samin Guo <samin.guo@starfivetech.com>
+ */
+
+#include <linux/clk.h>
+#include <linux/clockchips.h>
+#include <linux/clocksource.h>
+#include <linux/err.h>
+#include <linux/interrupt.h>
+#include <linux/io.h>
+#include <linux/iopoll.h>
+#include <linux/irq.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/of_device.h>
+#include <linux/platform_device.h>
+#include <linux/reset.h>
+#include <linux/sched_clock.h>
+
+/* Bias: Ch0-0x0, Ch1-0x40, Ch2-0x80, and so on. */
+#define JH7110_TIMER_CH_LEN		0x40
+#define JH7110_TIMER_CH_BASE(x)		((x) * JH7110_TIMER_CH_LEN)
+#define JH7110_TIMER_CH_MAX		4
+
+#define JH7110_CLOCK_SOURCE_RATING	200
+#define JH7110_VALID_BITS		32
+#define JH7110_DELAY_US			0
+#define JH7110_TIMEOUT_US		10000
+#define JH7110_CLOCKEVENT_RATING	300
+#define JH7110_TIMER_MAX_TICKS		0xffffffff
+#define JH7110_TIMER_MIN_TICKS		0xf
+#define JH7110_TIMER_RELOAD_VALUE	0
+
+#define JH7110_TIMER_INT_STATUS		0x00 /* RO[0:4]: Interrupt Status for channel0~4 */
+#define JH7110_TIMER_CTL		0x04 /* RW[0]: 0-continuous run, 1-single run */
+#define JH7110_TIMER_LOAD		0x08 /* RW: load value to counter */
+#define JH7110_TIMER_ENABLE		0x10 /* RW[0]: timer enable register */
+#define JH7110_TIMER_RELOAD		0x14 /* RW: write 1 or 0 both reload counter */
+#define JH7110_TIMER_VALUE		0x18 /* RO: timer value register */
+#define JH7110_TIMER_INT_CLR		0x20 /* RW: timer interrupt clear register */
+#define JH7110_TIMER_INT_MASK		0x24 /* RW[0]: timer interrupt mask register */
+
+#define JH7110_TIMER_INT_CLR_ENA	BIT(0)
+#define JH7110_TIMER_INT_CLR_AVA_MASK	BIT(1)
+
+struct jh7110_clkevt {
+	struct clock_event_device evt;
+	struct clocksource cs;
+	bool cs_is_valid;
+	struct clk *clk;
+	struct reset_control *rst;
+	u32 rate;
+	u32 reload_val;
+	void __iomem *base;
+	char name[sizeof("jh7110-timer.chX")];
+};
+
+struct jh7110_timer_priv {
+	struct clk *pclk;
+	struct reset_control *prst;
+	struct jh7110_clkevt clkevt[JH7110_TIMER_CH_MAX];
+};
+
+/* 0:continuous-run mode, 1:single-run mode */
+enum jh7110_timer_mode {
+	JH7110_TIMER_MODE_CONTIN,
+	JH7110_TIMER_MODE_SINGLE,
+};
+
+/* Interrupt Mask, 0:Unmask, 1:Mask */
+enum jh7110_timer_int_mask {
+	JH7110_TIMER_INT_ENA,
+	JH7110_TIMER_INT_DIS,
+};
+
+enum jh7110_timer_enable {
+	JH7110_TIMER_DIS,
+	JH7110_TIMER_ENA,
+};
+
+static inline struct jh7110_clkevt *to_jh7110_clkevt(struct clock_event_device *evt)
+{
+	return container_of(evt, struct jh7110_clkevt, evt);
+}
+
+/*
+ * BIT(0): Read value represent channel int status.
+ * Write 1 to this bit to clear interrupt. Write 0 has no effects.
+ * BIT(1): "1" means that it is clearing interrupt. BIT(0) can not be written.
+ */
+static inline int jh7110_timer_int_clear(struct jh7110_clkevt *clkevt)
+{
+	u32 value;
+	int ret;
+
+	/* Waiting interrupt can be cleared */
+	ret = readl_poll_timeout_atomic(clkevt->base + JH7110_TIMER_INT_CLR, value,
+					!(value & JH7110_TIMER_INT_CLR_AVA_MASK),
+					JH7110_DELAY_US, JH7110_TIMEOUT_US);
+	if (!ret)
+		writel(JH7110_TIMER_INT_CLR_ENA, clkevt->base + JH7110_TIMER_INT_CLR);
+
+	return ret;
+}
+
+static int jh7110_timer_start(struct jh7110_clkevt *clkevt)
+{
+	int ret;
+
+	/* Disable and clear interrupt first */
+	writel(JH7110_TIMER_INT_DIS, clkevt->base + JH7110_TIMER_INT_MASK);
+	ret = jh7110_timer_int_clear(clkevt);
+	if (ret)
+		return ret;
+
+	writel(JH7110_TIMER_INT_ENA, clkevt->base + JH7110_TIMER_INT_MASK);
+	writel(JH7110_TIMER_ENA, clkevt->base + JH7110_TIMER_ENABLE);
+
+	return 0;
+}
+
+static int jh7110_timer_shutdown(struct clock_event_device *evt)
+{
+	struct jh7110_clkevt *clkevt = to_jh7110_clkevt(evt);
+
+	writel(JH7110_TIMER_DIS, clkevt->base + JH7110_TIMER_ENABLE);
+	return jh7110_timer_int_clear(clkevt);
+}
+
+static void jh7110_timer_suspend(struct clock_event_device *evt)
+{
+	struct jh7110_clkevt *clkevt = to_jh7110_clkevt(evt);
+
+	clkevt->reload_val = readl(clkevt->base + JH7110_TIMER_LOAD);
+	jh7110_timer_shutdown(evt);
+}
+
+static void jh7110_timer_resume(struct clock_event_device *evt)
+{
+	struct jh7110_clkevt *clkevt = to_jh7110_clkevt(evt);
+
+	writel(clkevt->reload_val, clkevt->base + JH7110_TIMER_LOAD);
+	writel(JH7110_TIMER_RELOAD_VALUE, clkevt->base + JH7110_TIMER_RELOAD);
+	jh7110_timer_start(clkevt);
+}
+
+static int jh7110_timer_tick_resume(struct clock_event_device *evt)
+{
+	jh7110_timer_resume(evt);
+
+	return 0;
+}
+
+/* IRQ handler for the timer */
+static irqreturn_t jh7110_timer_interrupt(int irq, void *priv)
+{
+	struct clock_event_device *evt = (struct clock_event_device *)priv;
+	struct jh7110_clkevt *clkevt = to_jh7110_clkevt(evt);
+
+	if (jh7110_timer_int_clear(clkevt))
+		return IRQ_NONE;
+
+	if (evt->event_handler)
+		evt->event_handler(evt);
+
+	return IRQ_HANDLED;
+}
+
+static int jh7110_timer_set_periodic(struct clock_event_device *evt)
+{
+	struct jh7110_clkevt *clkevt = to_jh7110_clkevt(evt);
+	u32 periodic = DIV_ROUND_CLOSEST(clkevt->rate, HZ);
+
+	writel(JH7110_TIMER_MODE_CONTIN, clkevt->base + JH7110_TIMER_CTL);
+	writel(periodic, clkevt->base + JH7110_TIMER_LOAD);
+
+	return jh7110_timer_start(clkevt);
+}
+
+static int jh7110_timer_set_oneshot(struct clock_event_device *evt)
+{
+	struct jh7110_clkevt *clkevt = to_jh7110_clkevt(evt);
+
+	writel(JH7110_TIMER_MODE_SINGLE, clkevt->base + JH7110_TIMER_CTL);
+	writel(JH7110_TIMER_MAX_TICKS, clkevt->base + JH7110_TIMER_LOAD);
+
+	return jh7110_timer_start(clkevt);
+}
+
+static int jh7110_timer_set_next_event(unsigned long next,
+				       struct clock_event_device *evt)
+{
+	struct jh7110_clkevt *clkevt = to_jh7110_clkevt(evt);
+
+	writel(JH7110_TIMER_MODE_SINGLE, clkevt->base + JH7110_TIMER_CTL);
+	writel(next, clkevt->base + JH7110_TIMER_LOAD);
+
+	return jh7110_timer_start(clkevt);
+}
+
+static void jh7110_set_clockevent(struct clock_event_device *evt)
+{
+	evt->features = CLOCK_EVT_FEAT_PERIODIC |
+			CLOCK_EVT_FEAT_ONESHOT |
+			CLOCK_EVT_FEAT_DYNIRQ;
+	evt->set_state_shutdown = jh7110_timer_shutdown;
+	evt->set_state_periodic = jh7110_timer_set_periodic;
+	evt->set_state_oneshot = jh7110_timer_set_oneshot;
+	evt->set_state_oneshot_stopped = jh7110_timer_shutdown;
+	evt->tick_resume = jh7110_timer_tick_resume;
+	evt->set_next_event = jh7110_timer_set_next_event;
+	evt->suspend = jh7110_timer_suspend;
+	evt->resume = jh7110_timer_resume;
+	evt->rating = JH7110_CLOCKEVENT_RATING;
+}
+
+static u64 jh7110_timer_clocksource_read(struct clocksource *cs)
+{
+	struct jh7110_clkevt *clkevt = container_of(cs, struct jh7110_clkevt, cs);
+
+	return (u64)readl(clkevt->base + JH7110_TIMER_VALUE);
+}
+
+static int jh7110_clocksource_init(struct jh7110_clkevt *clkevt)
+{
+	int ret;
+
+	clkevt->cs.name = clkevt->name;
+	clkevt->cs.rating = JH7110_CLOCK_SOURCE_RATING;
+	clkevt->cs.read = jh7110_timer_clocksource_read;
+	clkevt->cs.mask = CLOCKSOURCE_MASK(JH7110_VALID_BITS);
+	clkevt->cs.flags = CLOCK_SOURCE_IS_CONTINUOUS;
+
+	ret = clocksource_register_hz(&clkevt->cs, clkevt->rate);
+	if (ret)
+		return ret;
+
+	clkevt->cs_is_valid = true; /* clocksource register done */
+	writel(JH7110_TIMER_MODE_CONTIN, clkevt->base + JH7110_TIMER_CTL);
+	writel(JH7110_TIMER_MAX_TICKS, clkevt->base + JH7110_TIMER_LOAD);
+
+	return jh7110_timer_start(clkevt);
+}
+
+static void jh7110_clockevents_register(struct jh7110_clkevt *clkevt)
+{
+	clkevt->rate = clk_get_rate(clkevt->clk);
+
+	jh7110_set_clockevent(&clkevt->evt);
+	clkevt->evt.name = clkevt->name;
+	clkevt->evt.cpumask = cpu_possible_mask;
+
+	clockevents_config_and_register(&clkevt->evt, clkevt->rate,
+					JH7110_TIMER_MIN_TICKS, JH7110_TIMER_MAX_TICKS);
+}
+
+static void jh7110_timer_release(void *data)
+{
+	struct jh7110_timer_priv *priv = data;
+	int i;
+
+	for (i = 0; i < JH7110_TIMER_CH_MAX; i++) {
+		/* Disable each channel of timer */
+		if (priv->clkevt[i].base)
+			writel(JH7110_TIMER_DIS, priv->clkevt[i].base + JH7110_TIMER_ENABLE);
+
+		/* Avoid no initialization in the loop of the probe */
+		if (!IS_ERR_OR_NULL(priv->clkevt[i].rst))
+			reset_control_assert(priv->clkevt[i].rst);
+
+		if (priv->clkevt[i].cs_is_valid)
+			clocksource_unregister(&priv->clkevt[i].cs);
+	}
+
+	reset_control_assert(priv->prst);
+}
+
+static int jh7110_timer_probe(struct platform_device *pdev)
+{
+	struct jh7110_timer_priv *priv;
+	struct jh7110_clkevt *clkevt;
+	char name[sizeof("chX")];
+	int ch;
+	int ret;
+	void __iomem *base;
+
+	priv = devm_kzalloc(&pdev->dev, sizeof(*priv), GFP_KERNEL);
+	if (!priv)
+		return -ENOMEM;
+
+	base = devm_platform_ioremap_resource(pdev, 0);
+	if (IS_ERR(base))
+		return dev_err_probe(&pdev->dev, PTR_ERR(base),
+				     "failed to map registers\n");
+
+	priv->prst = devm_reset_control_get_exclusive(&pdev->dev, "apb");
+	if (IS_ERR(priv->prst))
+		return dev_err_probe(&pdev->dev, PTR_ERR(priv->prst),
+				     "failed to get apb reset\n");
+
+	priv->pclk = devm_clk_get_enabled(&pdev->dev, "apb");
+	if (IS_ERR(priv->pclk))
+		return dev_err_probe(&pdev->dev, PTR_ERR(priv->pclk),
+				     "failed to get & enable apb clock\n");
+
+	ret = reset_control_deassert(priv->prst);
+	if (ret)
+		return dev_err_probe(&pdev->dev, ret, "failed to deassert apb reset\n");
+
+	ret = devm_add_action_or_reset(&pdev->dev, jh7110_timer_release, priv);
+	if (ret)
+		return ret;
+
+	for (ch = 0; ch < JH7110_TIMER_CH_MAX; ch++) {
+		clkevt = &priv->clkevt[ch];
+		snprintf(name, sizeof(name), "ch%d", ch);
+
+		clkevt->base = base + JH7110_TIMER_CH_BASE(ch);
+		/* Ensure timer is disabled */
+		writel(JH7110_TIMER_DIS, clkevt->base + JH7110_TIMER_ENABLE);
+
+		clkevt->rst = devm_reset_control_get_exclusive(&pdev->dev, name);
+		if (IS_ERR(clkevt->rst))
+			return PTR_ERR(clkevt->rst);
+
+		clkevt->clk = devm_clk_get_enabled(&pdev->dev, name);
+		if (IS_ERR(clkevt->clk))
+			return PTR_ERR(clkevt->clk);
+
+		ret = reset_control_deassert(clkevt->rst);
+		if (ret)
+			return ret;
+
+		clkevt->evt.irq = platform_get_irq(pdev, ch);
+		if (clkevt->evt.irq < 0)
+			return clkevt->evt.irq;
+
+		snprintf(clkevt->name, sizeof(clkevt->name), "jh7110-timer.ch%d", ch);
+		jh7110_clockevents_register(clkevt);
+
+		ret = devm_request_irq(&pdev->dev, clkevt->evt.irq, jh7110_timer_interrupt,
+				       IRQF_TIMER | IRQF_IRQPOLL,
+				       clkevt->name, &clkevt->evt);
+		if (ret)
+			return ret;
+
+		ret = jh7110_clocksource_init(clkevt);
+		if (ret)
+			return ret;
+	}
+
+	return 0;
+}
+
+static const struct of_device_id jh7110_timer_match[] = {
+	{ .compatible = "starfive,jh7110-timer", },
+	{ /* sentinel */ }
+};
+MODULE_DEVICE_TABLE(of, jh7110_timer_match);
+
+static struct platform_driver jh7110_timer_driver = {
+	.probe = jh7110_timer_probe,
+	.driver = {
+		.name = "jh7110-timer",
+		.of_match_table = jh7110_timer_match,
+	},
+};
+module_platform_driver(jh7110_timer_driver);
+
+MODULE_AUTHOR("Xingyu Wu <xingyu.wu@starfivetech.com>");
+MODULE_DESCRIPTION("StarFive JH7110 timer driver");
+MODULE_LICENSE("GPL");
