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Commit 0302637f authored by Vladimir Murzin's avatar Vladimir Murzin Committed by Daniel Lezcano
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clockevents/driversi/mps2: add MPS2 Timer driver 



MPS2 platform has simple 32 bits general purpose countdown timers.

The driver uses the first detected timer as a clocksource and the rest
of the timers as a clockevent

Acked-by: default avatarDaniel Lezcano <daniel.lezcano@linaro.org>
Signed-off-by: default avatarVladimir Murzin <vladimir.murzin@arm.com>
Signed-off-by: default avatarDaniel Lezcano <daniel.lezcano@linaro.org>
parent 96669fa4

drivers/clocksource/Kconfig

+6 −0
Original line number Diff line number Diff line
@@ -186,6 +186,12 @@ config CLKSRC_STM32 
	depends on OF && ARM && (ARCH_STM32 || COMPILE_TEST)

	select CLKSRC_MMIO



config CLKSRC_MPS2

	bool "Clocksource for MPS2 SoCs" if COMPILE_TEST

	depends on GENERIC_SCHED_CLOCK

	select CLKSRC_MMIO

	select CLKSRC_OF



config ARM_ARCH_TIMER

	bool

	select CLKSRC_OF if OF

drivers/clocksource/Makefile

+1 −0
Original line number Diff line number Diff line
@@ -39,6 +39,7 @@ obj-$(CONFIG_CLKSRC_EFM32) += time-efm32.o 
obj-$(CONFIG_CLKSRC_STM32)	+= timer-stm32.o

obj-$(CONFIG_CLKSRC_EXYNOS_MCT)	+= exynos_mct.o

obj-$(CONFIG_CLKSRC_LPC32XX)	+= time-lpc32xx.o

obj-$(CONFIG_CLKSRC_MPS2)	+= mps2-timer.o

obj-$(CONFIG_CLKSRC_SAMSUNG_PWM)	+= samsung_pwm_timer.o

obj-$(CONFIG_FSL_FTM_TIMER)	+= fsl_ftm_timer.o

obj-$(CONFIG_VF_PIT_TIMER)	+= vf_pit_timer.o

drivers/clocksource/mps2-timer.c

0 → 100644
+275 −0
Original line number Diff line number Diff line 
/*

 * Copyright (C) 2015 ARM Limited

 *

 * Author: Vladimir Murzin <vladimir.murzin@arm.com>

 *

 * This program is free software; you can redistribute it and/or modify

 * it under the terms of the GNU General Public License version 2 as

 * published by the Free Software Foundation.

 *

 */



#define pr_fmt(fmt)	KBUILD_MODNAME ": " fmt



#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/irq.h>

#include <linux/of_address.h>

#include <linux/of.h>

#include <linux/of_irq.h>

#include <linux/sched_clock.h>

#include <linux/slab.h>



#define TIMER_CTRL		0x0

#define TIMER_CTRL_ENABLE	BIT(0)

#define TIMER_CTRL_IE		BIT(3)



#define TIMER_VALUE		0x4

#define TIMER_RELOAD		0x8

#define TIMER_INT		0xc



struct clockevent_mps2 {

	void __iomem *reg;

	u32 clock_count_per_tick;

	struct clock_event_device clkevt;

};



static void __iomem *sched_clock_base;



static u64 notrace mps2_sched_read(void)

{

	return ~readl_relaxed(sched_clock_base + TIMER_VALUE);

}



static inline struct clockevent_mps2 *to_mps2_clkevt(struct clock_event_device *c)

{

	return container_of(c, struct clockevent_mps2, clkevt);

}



static void clockevent_mps2_writel(u32 val, struct clock_event_device *c, u32 offset)

{

	writel_relaxed(val, to_mps2_clkevt(c)->reg + offset);

}



static int mps2_timer_shutdown(struct clock_event_device *ce)

{

	clockevent_mps2_writel(0, ce, TIMER_RELOAD);

	clockevent_mps2_writel(0, ce, TIMER_CTRL);



	return 0;

}



static int mps2_timer_set_next_event(unsigned long next, struct clock_event_device *ce)

{

	clockevent_mps2_writel(next, ce, TIMER_VALUE);

	clockevent_mps2_writel(TIMER_CTRL_IE | TIMER_CTRL_ENABLE, ce, TIMER_CTRL);



	return 0;

}



static int mps2_timer_set_periodic(struct clock_event_device *ce)

{

	u32 clock_count_per_tick = to_mps2_clkevt(ce)->clock_count_per_tick;



	clockevent_mps2_writel(clock_count_per_tick, ce, TIMER_RELOAD);

	clockevent_mps2_writel(clock_count_per_tick, ce, TIMER_VALUE);

	clockevent_mps2_writel(TIMER_CTRL_IE | TIMER_CTRL_ENABLE, ce, TIMER_CTRL);



	return 0;

}



static irqreturn_t mps2_timer_interrupt(int irq, void *dev_id)

{

	struct clockevent_mps2 *ce = dev_id;

	u32 status = readl_relaxed(ce->reg + TIMER_INT);



	if (!status) {

		pr_warn("spurious interrupt\n");

		return IRQ_NONE;

	}



	writel_relaxed(1, ce->reg + TIMER_INT);



	ce->clkevt.event_handler(&ce->clkevt);



	return IRQ_HANDLED;

}



static int __init mps2_clockevent_init(struct device_node *np)

{

	void __iomem *base;

	struct clk *clk = NULL;

	struct clockevent_mps2 *ce;

	u32 rate;

	int irq, ret;

	const char *name = "mps2-clkevt";



	ret = of_property_read_u32(np, "clock-frequency", &rate);

	if (ret) {

		clk = of_clk_get(np, 0);

		if (IS_ERR(clk)) {

			ret = PTR_ERR(clk);

			pr_err("failed to get clock for clockevent: %d\n", ret);

			goto out;

		}



		ret = clk_prepare_enable(clk);

		if (ret) {

			pr_err("failed to enable clock for clockevent: %d\n", ret);

			goto out_clk_put;

		}



		rate = clk_get_rate(clk);

	}



	base = of_iomap(np, 0);

	if (!base) {

		ret = -EADDRNOTAVAIL;

		pr_err("failed to map register for clockevent: %d\n", ret);

		goto out_clk_disable;

	}



	irq = irq_of_parse_and_map(np, 0);

	if (!irq) {

		ret = -ENOENT;

		pr_err("failed to get irq for clockevent: %d\n", ret);

		goto out_iounmap;

	}



	ce = kzalloc(sizeof(*ce), GFP_KERNEL);

	if (!ce) {

		ret = -ENOMEM;

		goto out_iounmap;

	}



	ce->reg = base;

	ce->clock_count_per_tick = DIV_ROUND_CLOSEST(rate, HZ);

	ce->clkevt.irq = irq;

	ce->clkevt.name = name;

	ce->clkevt.rating = 200;

	ce->clkevt.features = CLOCK_EVT_FEAT_PERIODIC | CLOCK_EVT_FEAT_ONESHOT;

	ce->clkevt.cpumask = cpu_possible_mask;

	ce->clkevt.set_state_shutdown	= mps2_timer_shutdown,

	ce->clkevt.set_state_periodic	= mps2_timer_set_periodic,

	ce->clkevt.set_state_oneshot	= mps2_timer_shutdown,

	ce->clkevt.set_next_event	= mps2_timer_set_next_event;



	/* Ensure timer is disabled */

	writel_relaxed(0, base + TIMER_CTRL);



	ret = request_irq(irq, mps2_timer_interrupt, IRQF_TIMER, name, ce);

	if (ret) {

		pr_err("failed to request irq for clockevent: %d\n", ret);

		goto out_kfree;

	}



	clockevents_config_and_register(&ce->clkevt, rate, 0xf, 0xffffffff);



	return 0;



out_kfree:

	kfree(ce);

out_iounmap:

	iounmap(base);

out_clk_disable:

	/* clk_{disable, unprepare, put}() can handle NULL as a parameter */

	clk_disable_unprepare(clk);

out_clk_put:

	clk_put(clk);

out:

	return ret;

}



static int __init mps2_clocksource_init(struct device_node *np)

{

	void __iomem *base;

	struct clk *clk = NULL;

	u32 rate;

	int ret;

	const char *name = "mps2-clksrc";



	ret = of_property_read_u32(np, "clock-frequency", &rate);

	if (ret) {

		clk = of_clk_get(np, 0);

		if (IS_ERR(clk)) {

			ret = PTR_ERR(clk);

			pr_err("failed to get clock for clocksource: %d\n", ret);

			goto out;

		}



		ret = clk_prepare_enable(clk);

		if (ret) {

			pr_err("failed to enable clock for clocksource: %d\n", ret);

			goto out_clk_put;

		}



		rate = clk_get_rate(clk);

	}



	base = of_iomap(np, 0);

	if (!base) {

		ret = -EADDRNOTAVAIL;

		pr_err("failed to map register for clocksource: %d\n", ret);

		goto out_clk_disable;

	}



	/* Ensure timer is disabled */

	writel_relaxed(0, base + TIMER_CTRL);



	/* ... and set it up as free-running clocksource */

	writel_relaxed(0xffffffff, base + TIMER_VALUE);

	writel_relaxed(0xffffffff, base + TIMER_RELOAD);



	writel_relaxed(TIMER_CTRL_ENABLE, base + TIMER_CTRL);



	ret = clocksource_mmio_init(base + TIMER_VALUE, name,

				    rate, 200, 32,

				    clocksource_mmio_readl_down);

	if (ret) {

		pr_err("failed to init clocksource: %d\n", ret);

		goto out_iounmap;

	}



	sched_clock_base = base;

	sched_clock_register(mps2_sched_read, 32, rate);



	return 0;



out_iounmap:

	iounmap(base);

out_clk_disable:

	/* clk_{disable, unprepare, put}() can handle NULL as a parameter */

	clk_disable_unprepare(clk);

out_clk_put:

	clk_put(clk);

out:

	return ret;

}



static void __init mps2_timer_init(struct device_node *np)

{

	static int has_clocksource, has_clockevent;

	int ret;



	if (!has_clocksource) {

		ret = mps2_clocksource_init(np);

		if (!ret) {

			has_clocksource = 1;

			return;

		}

	}



	if (!has_clockevent) {

		ret = mps2_clockevent_init(np);

		if (!ret) {

			has_clockevent = 1;

			return;

		}

	}

}



CLOCKSOURCE_OF_DECLARE(mps2_timer, "arm,mps2-timer", mps2_timer_init);