[PATCH v2 2/3] clocksource: Add StarFive timer driver

[Xingyu Wu <xingyu.wu@starfivetech.com>]

Add timer driver for the StarFive JH7110 SoC.

Signed-off-by: Xingyu Wu <xingyu.wu@starfivetech.com>
---
 MAINTAINERS                          |   7 +
 drivers/clocksource/Kconfig          |  12 +
 drivers/clocksource/Makefile         |   1 +
 drivers/clocksource/timer-starfive.c | 390 +++++++++++++++++++++++++++
 drivers/clocksource/timer-starfive.h |  96 +++++++
 5 files changed, 506 insertions(+)
 create mode 100644 drivers/clocksource/timer-starfive.c
 create mode 100644 drivers/clocksource/timer-starfive.h

diff --git a/MAINTAINERS b/MAINTAINERS
index 958b7ec118b4..dac6298d8f6e 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -19958,6 +19958,13 @@ S:	Maintained
 T:	git https://git.kernel.org/pub/scm/linux/kernel/git/conor/linux.git/
 F:	drivers/soc/starfive/
 
+STARFIVE TIMER DRIVER
+M:	Samin Guo <samin.guo@starfivetech.com>
+M:	Xingyu Wu <xingyu.wu@starfivetech.com>
+S:	Supported
+F:	Documentation/devicetree/bindings/timer/starfive*
+F:	drivers/clocksource/timer-starfive*
+
 STARFIVE TRNG DRIVER
 M:	Jia Jie Ho <jiajie.ho@starfivetech.com>
 S:	Supported
diff --git a/drivers/clocksource/Kconfig b/drivers/clocksource/Kconfig
index 5fc8f0e7fb38..35daf07d4db7 100644
--- a/drivers/clocksource/Kconfig
+++ b/drivers/clocksource/Kconfig
@@ -630,6 +630,18 @@ config RISCV_TIMER
 	  is accessed via both the SBI and the rdcycle instruction.  This is
 	  required for all RISC-V systems.
 
+config STARFIVE_TIMER
+	bool "Timer for the STARFIVE SoCs"
+	depends on ARCH_STARFIVE || COMPILE_TEST
+	select TIMER_OF
+	select CLKSRC_MMIO
+	default ARCH_STARFIVE
+	help
+	  This enables the timer for StarFive SoCs. On RISC-V platform,
+	  the system has started RISCV_TIMER. But you can also use this timer
+	  to do a lot more on StarFive SoCs. This timer can provide high
+	  precision and four channels to use in JH7110 SoC.
+
 config CLINT_TIMER
 	bool "CLINT Timer for the RISC-V platform" if COMPILE_TEST
 	depends on GENERIC_SCHED_CLOCK && RISCV
diff --git a/drivers/clocksource/Makefile b/drivers/clocksource/Makefile
index 64ab547de97b..276695d95cdc 100644
--- a/drivers/clocksource/Makefile
+++ b/drivers/clocksource/Makefile
@@ -80,6 +80,7 @@ obj-$(CONFIG_INGENIC_TIMER)		+= ingenic-timer.o
 obj-$(CONFIG_CLKSRC_ST_LPC)		+= clksrc_st_lpc.o
 obj-$(CONFIG_X86_NUMACHIP)		+= numachip.o
 obj-$(CONFIG_RISCV_TIMER)		+= timer-riscv.o
+obj-$(CONFIG_STARFIVE_TIMER)		+= timer-starfive.o
 obj-$(CONFIG_CLINT_TIMER)		+= timer-clint.o
 obj-$(CONFIG_CSKY_MP_TIMER)		+= timer-mp-csky.o
 obj-$(CONFIG_GX6605S_TIMER)		+= timer-gx6605s.o
diff --git a/drivers/clocksource/timer-starfive.c b/drivers/clocksource/timer-starfive.c
new file mode 100644
index 000000000000..53163948ed86
--- /dev/null
+++ b/drivers/clocksource/timer-starfive.c
@@ -0,0 +1,390 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Starfive Timer driver
+ *
+ * Copyright (C) 2022 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>
+
+#include "timer-starfive.h"
+
+static const struct starfive_timer_chan_base starfive_timer_jh7110_base = {
+	.ctrl		= STARFIVE_TIMER_JH7110_CTL,
+	.load		= STARFIVE_TIMER_JH7110_LOAD,
+	.enable		= STARFIVE_TIMER_JH7110_ENABLE,
+	.reload		= STARFIVE_TIMER_JH7110_RELOAD,
+	.value		= STARFIVE_TIMER_JH7110_VALUE,
+	.intclr		= STARFIVE_TIMER_JH7110_INT_CLR,
+	.intmask	= STARFIVE_TIMER_JH7110_INT_MASK,
+	.channel_num	= STARFIVE_TIMER_CH_4,
+	.channel_base	= {STARFIVE_TIMER_CH_BASE(0), STARFIVE_TIMER_CH_BASE(1),
+			   STARFIVE_TIMER_CH_BASE(2), STARFIVE_TIMER_CH_BASE(3)},
+};
+
+static inline struct starfive_clkevt *to_starfive_clkevt(struct clock_event_device *evt)
+{
+	return container_of(evt, struct starfive_clkevt, evt);
+}
+
+/* 0:continuous-run mode, 1:single-run mode */
+static inline void starfive_timer_set_mod(struct starfive_clkevt *clkevt, int mod)
+{
+	writel(mod, clkevt->ctrl);
+}
+
+/* Interrupt Mask Register, 0:Unmask, 1:Mask */
+static inline void starfive_timer_int_enable(struct starfive_clkevt *clkevt)
+{
+	writel(STARFIVE_TIMER_INTMASK_DIS, clkevt->intmask);
+}
+
+static inline void starfive_timer_int_disable(struct starfive_clkevt *clkevt)
+{
+	writel(STARFIVE_TIMER_INTMASK_ENA, clkevt->intmask);
+}
+
+/*
+ * BIT(0): Read value represent channel intr 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 starfive_timer_int_clear(struct starfive_clkevt *clkevt)
+{
+	u32 value;
+	int ret;
+
+	/* waiting interrupt can be to clearing */
+	ret = readl_poll_timeout_atomic(clkevt->intclr, value,
+					!(value & STARFIVE_TIMER_JH7110_INT_CLR_AVA_MASK),
+					STARFIVE_DELAY_US, STARFIVE_TIMEOUT_US);
+	if (!ret)
+		writel(0x1, clkevt->intclr);
+
+	return ret;
+}
+
+/*
+ * The initial value to be loaded into the
+ * counter and is also used as the reload value.
+ * val = clock rate --> 1s
+ */
+static inline void starfive_timer_set_load(struct starfive_clkevt *clkevt, u32 val)
+{
+	writel(val, clkevt->load);
+}
+
+static inline u32 starfive_timer_get_val(struct starfive_clkevt *clkevt)
+{
+	return readl(clkevt->value);
+}
+
+/*
+ * Write RELOAD register to reload preset value to counter.
+ * (Write 0 and write 1 are both ok)
+ */
+static inline void starfive_timer_set_reload(struct starfive_clkevt *clkevt)
+{
+	writel(0, clkevt->reload);
+}
+
+static inline void starfive_timer_enable(struct starfive_clkevt *clkevt)
+{
+	writel(STARFIVE_TIMER_ENA, clkevt->enable);
+}
+
+static inline void starfive_timer_disable(struct starfive_clkevt *clkevt)
+{
+	writel(STARFIVE_TIMER_DIS, clkevt->enable);
+}
+
+static int starfive_timer_int_init_enable(struct starfive_clkevt *clkevt)
+{
+	int ret;
+
+	starfive_timer_int_disable(clkevt);
+	ret = starfive_timer_int_clear(clkevt);
+	if (ret)
+		return ret;
+
+	starfive_timer_int_enable(clkevt);
+	starfive_timer_enable(clkevt);
+
+	return 0;
+}
+
+static int starfive_timer_shutdown(struct clock_event_device *evt)
+{
+	struct starfive_clkevt *clkevt = to_starfive_clkevt(evt);
+
+	starfive_timer_disable(clkevt);
+	return starfive_timer_int_clear(clkevt);
+}
+
+static void starfive_timer_suspend(struct clock_event_device *evt)
+{
+	struct starfive_clkevt *clkevt = to_starfive_clkevt(evt);
+
+	clkevt->reload_val = starfive_timer_get_val(clkevt);
+	starfive_timer_shutdown(evt);
+}
+
+static void starfive_timer_resume(struct clock_event_device *evt)
+{
+	struct starfive_clkevt *clkevt = to_starfive_clkevt(evt);
+
+	starfive_timer_set_load(clkevt, clkevt->reload_val);
+	starfive_timer_set_reload(clkevt);
+	starfive_timer_int_enable(clkevt);
+	starfive_timer_enable(clkevt);
+}
+
+static int starfive_timer_tick_resume(struct clock_event_device *evt)
+{
+	starfive_timer_resume(evt);
+
+	return 0;
+}
+
+static int starfive_clocksource_init(struct starfive_clkevt *clkevt)
+{
+	int ret;
+
+	starfive_timer_set_mod(clkevt, STARFIVE_TIMER_MOD_CONTIN);
+	starfive_timer_set_load(clkevt, STARFIVE_TIMER_MAX_TICKS);
+	ret = starfive_timer_int_init_enable(clkevt);
+	if (ret)
+		return ret;
+
+	return clocksource_mmio_init(clkevt->value, clkevt->name, clkevt->rate,
+				     STARFIVE_CLOCK_SOURCE_RATING, STARFIVE_VALID_BITS,
+				     clocksource_mmio_readl_down);
+}
+
+/* IRQ handler for the timer */
+static irqreturn_t starfive_timer_interrupt(int irq, void *priv)
+{
+	struct clock_event_device *evt = (struct clock_event_device *)priv;
+	struct starfive_clkevt *clkevt = to_starfive_clkevt(evt);
+
+	if (starfive_timer_int_clear(clkevt))
+		return IRQ_NONE;
+
+	if (evt->event_handler)
+		evt->event_handler(evt);
+
+	return IRQ_HANDLED;
+}
+
+static int starfive_timer_set_periodic(struct clock_event_device *evt)
+{
+	struct starfive_clkevt *clkevt = to_starfive_clkevt(evt);
+
+	starfive_timer_disable(clkevt);
+	starfive_timer_set_mod(clkevt, STARFIVE_TIMER_MOD_CONTIN);
+	starfive_timer_set_load(clkevt, clkevt->periodic);
+
+	return starfive_timer_int_init_enable(clkevt);
+}
+
+static int starfive_timer_set_oneshot(struct clock_event_device *evt)
+{
+	struct starfive_clkevt *clkevt = to_starfive_clkevt(evt);
+
+	starfive_timer_disable(clkevt);
+	starfive_timer_set_mod(clkevt, STARFIVE_TIMER_MOD_SINGLE);
+	starfive_timer_set_load(clkevt, STARFIVE_TIMER_MAX_TICKS);
+
+	return starfive_timer_int_init_enable(clkevt);
+}
+
+static int starfive_timer_set_next_event(unsigned long next,
+					 struct clock_event_device *evt)
+{
+	struct starfive_clkevt *clkevt = to_starfive_clkevt(evt);
+
+	starfive_timer_disable(clkevt);
+	starfive_timer_set_mod(clkevt, STARFIVE_TIMER_MOD_SINGLE);
+	starfive_timer_set_load(clkevt, next);
+	starfive_timer_enable(clkevt);
+
+	return 0;
+}
+
+static void starfive_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 = starfive_timer_shutdown;
+	evt->set_state_periodic = starfive_timer_set_periodic;
+	evt->set_state_oneshot = starfive_timer_set_oneshot;
+	evt->set_state_oneshot_stopped = starfive_timer_shutdown;
+	evt->tick_resume = starfive_timer_tick_resume;
+	evt->set_next_event = starfive_timer_set_next_event;
+	evt->suspend = starfive_timer_suspend;
+	evt->resume = starfive_timer_resume;
+	evt->rating = STARFIVE_CLOCKEVENT_RATING;
+}
+
+static void starfive_clockevents_register(struct starfive_clkevt *clkevt)
+{
+	clkevt->rate = clk_get_rate(clkevt->clk);
+	clkevt->periodic = DIV_ROUND_CLOSEST(clkevt->rate, HZ);
+
+	starfive_set_clockevent(&clkevt->evt);
+	clkevt->evt.name = clkevt->name;
+	clkevt->evt.irq = clkevt->irq;
+	clkevt->evt.cpumask = cpu_possible_mask;
+
+	clockevents_config_and_register(&clkevt->evt, clkevt->rate,
+					STARFIVE_TIMER_MIN_TICKS, STARFIVE_TIMER_MAX_TICKS);
+}
+
+static void __init starfive_clkevt_base_init(const struct starfive_timer_chan_base *timer,
+					     struct starfive_clkevt *clkevt,
+					     void __iomem *base, int ch)
+{
+	void __iomem *channel_base;
+
+	channel_base = base + timer->channel_base[ch];
+	clkevt->base = channel_base;
+	clkevt->ctrl = channel_base + timer->ctrl;
+	clkevt->load = channel_base + timer->load;
+	clkevt->enable = channel_base + timer->enable;
+	clkevt->reload = channel_base + timer->reload;
+	clkevt->value = channel_base + timer->value;
+	clkevt->intclr = channel_base + timer->intclr;
+	clkevt->intmask = channel_base + timer->intmask;
+}
+
+static int __init starfive_timer_probe(struct platform_device *pdev)
+{
+	const struct starfive_timer_chan_base *timer_base = of_device_get_match_data(&pdev->dev);
+	char name[10];
+	struct starfive_timer_priv *priv;
+	struct starfive_clkevt *clkevt;
+	struct clk *pclk;
+	struct reset_control *rst;
+	int ch;
+	int ret;
+
+	priv = devm_kzalloc(&pdev->dev, struct_size(priv, clkevt, timer_base->channel_num),
+			    GFP_KERNEL);
+	if (!priv)
+		return -ENOMEM;
+
+	priv->base = devm_platform_ioremap_resource(pdev, 0);
+	if (IS_ERR(priv->base))
+		return dev_err_probe(&pdev->dev, PTR_ERR(priv->base),
+				     "failed to map registers\n");
+
+	rst = devm_reset_control_get_exclusive(&pdev->dev, "apb");
+	if (IS_ERR(rst))
+		return dev_err_probe(&pdev->dev, PTR_ERR(rst), "failed to get apb reset\n");
+
+	pclk = devm_clk_get_enabled(&pdev->dev, "apb");
+	if (IS_ERR(pclk))
+		return dev_err_probe(&pdev->dev, PTR_ERR(pclk),
+				     "failed to get & enable apb clock\n");
+
+	ret = reset_control_deassert(rst);
+	if (ret)
+		goto err;
+
+	priv->dev = &pdev->dev;
+	platform_set_drvdata(pdev, priv);
+
+	for (ch = 0; ch < timer_base->channel_num; ch++) {
+		clkevt = &priv->clkevt[ch];
+		snprintf(name, sizeof(name), "ch%d", ch);
+
+		starfive_clkevt_base_init(timer_base, clkevt, priv->base, ch);
+		/* Ensure timers are disabled */
+		starfive_timer_disable(clkevt);
+
+		rst = devm_reset_control_get_exclusive(&pdev->dev, name);
+		if (IS_ERR(rst)) {
+			ret = PTR_ERR(rst);
+			goto err;
+		}
+
+		clkevt->clk = devm_clk_get_enabled(&pdev->dev, name);
+		if (IS_ERR(clkevt->clk)) {
+			ret = PTR_ERR(clkevt->clk);
+			goto err;
+		}
+
+		ret = reset_control_deassert(rst);
+		if (ret)
+			goto ch_err;
+
+		clkevt->irq = platform_get_irq(pdev, ch);
+		if (clkevt->irq < 0) {
+			ret = clkevt->irq;
+			goto ch_err;
+		}
+
+		snprintf(clkevt->name, sizeof(clkevt->name), "%s.ch%d", pdev->name, ch);
+		starfive_clockevents_register(clkevt);
+
+		ret = devm_request_irq(&pdev->dev, clkevt->irq, starfive_timer_interrupt,
+				       IRQF_TIMER | IRQF_IRQPOLL,
+				       clkevt->name, &clkevt->evt);
+		if (ret)
+			goto ch_err;
+
+		ret = starfive_clocksource_init(clkevt);
+		if (ret)
+			goto ch_err;
+	}
+
+	return 0;
+
+ch_err:
+	/* Only unregister the failed channel and the rest timer channels continue to work. */
+	clk_disable_unprepare(clkevt->clk);
+err:
+	/* If no other channel successfully registers, pclk should be disabled. */
+	if (!ch)
+		clk_disable_unprepare(pclk);
+
+	return ret;
+}
+
+static const struct of_device_id starfive_timer_match[] = {
+	{ .compatible = "starfive,jh7110-timer", .data = &starfive_timer_jh7110_base },
+	{ /* sentinel */ }
+};
+MODULE_DEVICE_TABLE(of, starfive_timer_match);
+
+static struct platform_driver starfive_timer_driver = {
+	.probe = starfive_timer_probe,
+	.driver = {
+		.name = "starfive-timer",
+		.of_match_table = starfive_timer_match,
+	},
+};
+module_platform_driver(starfive_timer_driver);
+
+MODULE_AUTHOR("Xingyu Wu <xingyu.wu@starfivetech.com>");
+MODULE_DESCRIPTION("StarFive timer driver");
+MODULE_LICENSE("GPL");
diff --git a/drivers/clocksource/timer-starfive.h b/drivers/clocksource/timer-starfive.h
new file mode 100644
index 000000000000..62eb630cc98d
--- /dev/null
+++ b/drivers/clocksource/timer-starfive.h
@@ -0,0 +1,96 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * Copyright (C) 2022 StarFive Technology Co., Ltd.
+ */
+
+#ifndef __STARFIVE_TIMER_H__
+#define __STARFIVE_TIMER_H__
+
+/* Bias: Ch0-0x0, Ch1-0x40, Ch2-0x80, and so on. */
+#define STARFIVE_TIMER_CH_LEN			0x40
+#define STARFIVE_TIMER_CH_BASE(x)		((STARFIVE_TIMER_CH_##x) * STARFIVE_TIMER_CH_LEN)
+
+#define STARFIVE_CLOCK_SOURCE_RATING		200
+#define STARFIVE_VALID_BITS			32
+#define STARFIVE_DELAY_US			0
+#define STARFIVE_TIMEOUT_US			10000
+#define STARFIVE_CLOCKEVENT_RATING		300
+#define STARFIVE_TIMER_MAX_TICKS		0xffffffff
+#define STARFIVE_TIMER_MIN_TICKS		0xf
+
+#define STARFIVE_TIMER_JH7110_INT_STATUS	0x00 /* RO[0:4]: Interrupt Status for channel0~4 */
+#define STARFIVE_TIMER_JH7110_CTL		0x04 /* RW[0]: 0-continuous run, 1-single run */
+#define STARFIVE_TIMER_JH7110_LOAD		0x08 /* RW: load value to counter */
+#define STARFIVE_TIMER_JH7110_ENABLE		0x10 /* RW[0]: timer enable register */
+#define STARFIVE_TIMER_JH7110_RELOAD		0x14 /* RW: write 1 or 0 both reload counter */
+#define STARFIVE_TIMER_JH7110_VALUE		0x18 /* RO: timer value register */
+#define STARFIVE_TIMER_JH7110_INT_CLR		0x20 /* RW: timer interrupt clear register */
+#define STARFIVE_TIMER_JH7110_INT_MASK		0x24 /* RW[0]: timer interrupt mask register */
+#define STARFIVE_TIMER_JH7110_INT_CLR_AVA_MASK	BIT(1)
+
+enum STARFIVE_TIMER_CH {
+	STARFIVE_TIMER_CH_0 = 0,
+	STARFIVE_TIMER_CH_1,
+	STARFIVE_TIMER_CH_2,
+	STARFIVE_TIMER_CH_3,
+	STARFIVE_TIMER_CH_4,
+	STARFIVE_TIMER_CH_5,
+	STARFIVE_TIMER_CH_6,
+	STARFIVE_TIMER_CH_7,
+	STARFIVE_TIMER_CH_MAX
+};
+
+enum STARFIVE_TIMER_INTMASK {
+	STARFIVE_TIMER_INTMASK_DIS = 0,
+	STARFIVE_TIMER_INTMASK_ENA = 1
+};
+
+enum STARFIVE_TIMER_MOD {
+	STARFIVE_TIMER_MOD_CONTIN = 0,
+	STARFIVE_TIMER_MOD_SINGLE = 1
+};
+
+enum STARFIVE_TIMER_CTL_EN {
+	STARFIVE_TIMER_DIS = 0,
+	STARFIVE_TIMER_ENA = 1
+};
+
+struct starfive_timer_chan_base {
+	/* Resgister */
+	unsigned int ctrl;
+	unsigned int load;
+	unsigned int enable;
+	unsigned int reload;
+	unsigned int value;
+	unsigned int intclr;
+	unsigned int intmask;
+
+	unsigned int channel_num;	/* timer channel numbers */
+	unsigned int channel_base[];
+};
+
+struct starfive_clkevt {
+	struct clock_event_device evt;
+	struct clk *clk;
+	char name[20];
+	int irq;
+	u32 periodic;
+	u32 rate;
+	u32 reload_val;
+	void __iomem *base;
+	void __iomem *ctrl;
+	void __iomem *load;
+	void __iomem *enable;
+	void __iomem *reload;
+	void __iomem *value;
+	void __iomem *intclr;
+	void __iomem *intmask;
+};
+
+struct starfive_timer_priv {
+	struct device *dev;
+	void __iomem *base;
+	struct starfive_clkevt clkevt[];
+};
+
+#endif /* __STARFIVE_TIMER_H__ */
-- 
2.25.1