drivers/clocksource/arm_arch_timer.c - kernel/msm-4.19 - Gitiles

 /*
  *  linux/drivers/clocksource/arm_arch_timer.c
  *
  *  Copyright (C) 2011 ARM Ltd.
  *  All Rights Reserved
  *
  * 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.
  */
 #include <linux/init.h>
 #include <linux/kernel.h>
 #include <linux/device.h>
 #include <linux/smp.h>
 #include <linux/cpu.h>
 #include <linux/clockchips.h>
 #include <linux/interrupt.h>
 #include <linux/of_irq.h>
 #include <linux/io.h>

 #include <asm/arch_timer.h>
 #include <asm/virt.h>

 #include <clocksource/arm_arch_timer.h>

 static u32 arch_timer_rate;

 enum ppi_nr {
 	PHYS_SECURE_PPI,
 	PHYS_NONSECURE_PPI,
 	VIRT_PPI,
 	HYP_PPI,
 	MAX_TIMER_PPI
 };

 static int arch_timer_ppi[MAX_TIMER_PPI];

 static struct clock_event_device __percpu *arch_timer_evt;

 static bool arch_timer_use_virtual = true;

 /*
  * Architected system timer support.
  */

 static inline irqreturn_t timer_handler(const int access,
 					struct clock_event_device *evt)
 {
 	unsigned long ctrl;
 	ctrl = arch_timer_reg_read(access, ARCH_TIMER_REG_CTRL);
 	if (ctrl & ARCH_TIMER_CTRL_IT_STAT) {
 		ctrl |= ARCH_TIMER_CTRL_IT_MASK;
 		arch_timer_reg_write(access, ARCH_TIMER_REG_CTRL, ctrl);
 		evt->event_handler(evt);
 		return IRQ_HANDLED;
 	}

 	return IRQ_NONE;
 }

 static irqreturn_t arch_timer_handler_virt(int irq, void *dev_id)
 {
 	struct clock_event_device *evt = dev_id;

 	return timer_handler(ARCH_TIMER_VIRT_ACCESS, evt);
 }

 static irqreturn_t arch_timer_handler_phys(int irq, void *dev_id)
 {
 	struct clock_event_device *evt = dev_id;

 	return timer_handler(ARCH_TIMER_PHYS_ACCESS, evt);
 }

 static inline void timer_set_mode(const int access, int mode)
 {
 	unsigned long ctrl;
 	switch (mode) {
 	case CLOCK_EVT_MODE_UNUSED:
 	case CLOCK_EVT_MODE_SHUTDOWN:
 		ctrl = arch_timer_reg_read(access, ARCH_TIMER_REG_CTRL);
 		ctrl &= ~ARCH_TIMER_CTRL_ENABLE;
 		arch_timer_reg_write(access, ARCH_TIMER_REG_CTRL, ctrl);
 		break;
 	default:
 		break;
 	}
 }

 static void arch_timer_set_mode_virt(enum clock_event_mode mode,
 				     struct clock_event_device *clk)
 {
 	timer_set_mode(ARCH_TIMER_VIRT_ACCESS, mode);
 }

 static void arch_timer_set_mode_phys(enum clock_event_mode mode,
 				     struct clock_event_device *clk)
 {
 	timer_set_mode(ARCH_TIMER_PHYS_ACCESS, mode);
 }

 static inline void set_next_event(const int access, unsigned long evt)
 {
 	unsigned long ctrl;
 	ctrl = arch_timer_reg_read(access, ARCH_TIMER_REG_CTRL);
 	ctrl |= ARCH_TIMER_CTRL_ENABLE;
 	ctrl &= ~ARCH_TIMER_CTRL_IT_MASK;
 	arch_timer_reg_write(access, ARCH_TIMER_REG_TVAL, evt);
 	arch_timer_reg_write(access, ARCH_TIMER_REG_CTRL, ctrl);
 }

 static int arch_timer_set_next_event_virt(unsigned long evt,
 					  struct clock_event_device *unused)
 {
 	set_next_event(ARCH_TIMER_VIRT_ACCESS, evt);
 	return 0;
 }

 static int arch_timer_set_next_event_phys(unsigned long evt,
 					  struct clock_event_device *unused)
 {
 	set_next_event(ARCH_TIMER_PHYS_ACCESS, evt);
 	return 0;
 }

 static int __cpuinit arch_timer_setup(struct clock_event_device *clk)
 {
 	clk->features = CLOCK_EVT_FEAT_ONESHOT | CLOCK_EVT_FEAT_C3STOP;
 	clk->name = "arch_sys_timer";
 	clk->rating = 450;
 	if (arch_timer_use_virtual) {
 		clk->irq = arch_timer_ppi[VIRT_PPI];
 		clk->set_mode = arch_timer_set_mode_virt;
 		clk->set_next_event = arch_timer_set_next_event_virt;
 	} else {
 		clk->irq = arch_timer_ppi[PHYS_SECURE_PPI];
 		clk->set_mode = arch_timer_set_mode_phys;
 		clk->set_next_event = arch_timer_set_next_event_phys;
 	}

 	clk->cpumask = cpumask_of(smp_processor_id());

 	clk->set_mode(CLOCK_EVT_MODE_SHUTDOWN, NULL);

 	clockevents_config_and_register(clk, arch_timer_rate,
 					0xf, 0x7fffffff);

 	if (arch_timer_use_virtual)
 		enable_percpu_irq(arch_timer_ppi[VIRT_PPI], 0);
 	else {
 		enable_percpu_irq(arch_timer_ppi[PHYS_SECURE_PPI], 0);
 		if (arch_timer_ppi[PHYS_NONSECURE_PPI])
 			enable_percpu_irq(arch_timer_ppi[PHYS_NONSECURE_PPI], 0);
 	}

 	arch_counter_set_user_access();

 	return 0;
 }

 static int arch_timer_available(void)
 {
 	u32 freq;

 	if (arch_timer_rate == 0) {
 		freq = arch_timer_get_cntfrq();

 		/* Check the timer frequency. */
 		if (freq == 0) {
 			pr_warn("Architected timer frequency not available\n");
 			return -EINVAL;
 		}

 		arch_timer_rate = freq;
 	}

 	pr_info_once("Architected local timer running at %lu.%02luMHz (%s).\n",
 		     (unsigned long)arch_timer_rate / 1000000,
 		     (unsigned long)(arch_timer_rate / 10000) % 100,
 		     arch_timer_use_virtual ? "virt" : "phys");
 	return 0;
 }

 u32 arch_timer_get_rate(void)
 {
 	return arch_timer_rate;
 }

 /*
  * Some external users of arch_timer_read_counter (e.g. sched_clock) may try to
  * call it before it has been initialised. Rather than incur a performance
  * penalty checking for initialisation, provide a default implementation that
  * won't lead to time appearing to jump backwards.
  */
 static u64 arch_timer_read_zero(void)
 {
 	return 0;
 }

 u64 (*arch_timer_read_counter)(void) = arch_timer_read_zero;

 static cycle_t arch_counter_read(struct clocksource *cs)
 {
 	return arch_timer_read_counter();
 }

 static cycle_t arch_counter_read_cc(const struct cyclecounter *cc)
 {
 	return arch_timer_read_counter();
 }

 static struct clocksource clocksource_counter = {
 	.name	= "arch_sys_counter",
 	.rating	= 400,
 	.read	= arch_counter_read,
 	.mask	= CLOCKSOURCE_MASK(56),
 	.flags	= CLOCK_SOURCE_IS_CONTINUOUS,
 };

 static struct cyclecounter cyclecounter = {
 	.read	= arch_counter_read_cc,
 	.mask	= CLOCKSOURCE_MASK(56),
 };

 static struct timecounter timecounter;

 struct timecounter *arch_timer_get_timecounter(void)
 {
 	return &timecounter;
 }

 static void __cpuinit arch_timer_stop(struct clock_event_device *clk)
 {
 	pr_debug("arch_timer_teardown disable IRQ%d cpu #%d\n",
 		 clk->irq, smp_processor_id());

 	if (arch_timer_use_virtual)
 		disable_percpu_irq(arch_timer_ppi[VIRT_PPI]);
 	else {
 		disable_percpu_irq(arch_timer_ppi[PHYS_SECURE_PPI]);
 		if (arch_timer_ppi[PHYS_NONSECURE_PPI])
 			disable_percpu_irq(arch_timer_ppi[PHYS_NONSECURE_PPI]);
 	}

 	clk->set_mode(CLOCK_EVT_MODE_UNUSED, clk);
 }

 static int __cpuinit arch_timer_cpu_notify(struct notifier_block *self,
 					   unsigned long action, void *hcpu)
 {
 	/*
 	 * Grab cpu pointer in each case to avoid spurious
 	 * preemptible warnings
 	 */
 	switch (action & ~CPU_TASKS_FROZEN) {
 	case CPU_STARTING:
 		arch_timer_setup(this_cpu_ptr(arch_timer_evt));
 		break;
 	case CPU_DYING:
 		arch_timer_stop(this_cpu_ptr(arch_timer_evt));
 		break;
 	}

 	return NOTIFY_OK;
 }

 static struct notifier_block arch_timer_cpu_nb __cpuinitdata = {
 	.notifier_call = arch_timer_cpu_notify,
 };

 static int __init arch_timer_register(void)
 {
 	int err;
 	int ppi;

 	err = arch_timer_available();
 	if (err)
 		goto out;

 	arch_timer_evt = alloc_percpu(struct clock_event_device);
 	if (!arch_timer_evt) {
 		err = -ENOMEM;
 		goto out;
 	}

 	clocksource_register_hz(&clocksource_counter, arch_timer_rate);
 	cyclecounter.mult = clocksource_counter.mult;
 	cyclecounter.shift = clocksource_counter.shift;
 	timecounter_init(&timecounter, &cyclecounter,
 			 arch_counter_get_cntpct());

 	if (arch_timer_use_virtual) {
 		ppi = arch_timer_ppi[VIRT_PPI];
 		err = request_percpu_irq(ppi, arch_timer_handler_virt,
 					 "arch_timer", arch_timer_evt);
 	} else {
 		ppi = arch_timer_ppi[PHYS_SECURE_PPI];
 		err = request_percpu_irq(ppi, arch_timer_handler_phys,
 					 "arch_timer", arch_timer_evt);
 		if (!err && arch_timer_ppi[PHYS_NONSECURE_PPI]) {
 			ppi = arch_timer_ppi[PHYS_NONSECURE_PPI];
 			err = request_percpu_irq(ppi, arch_timer_handler_phys,
 						 "arch_timer", arch_timer_evt);
 			if (err)
 				free_percpu_irq(arch_timer_ppi[PHYS_SECURE_PPI],
 						arch_timer_evt);
 		}
 	}

 	if (err) {
 		pr_err("arch_timer: can't register interrupt %d (%d)\n",
 		       ppi, err);
 		goto out_free;
 	}

 	err = register_cpu_notifier(&arch_timer_cpu_nb);
 	if (err)
 		goto out_free_irq;

 	/* Immediately configure the timer on the boot CPU */
 	arch_timer_setup(this_cpu_ptr(arch_timer_evt));

 	return 0;

 out_free_irq:
 	if (arch_timer_use_virtual)
 		free_percpu_irq(arch_timer_ppi[VIRT_PPI], arch_timer_evt);
 	else {
 		free_percpu_irq(arch_timer_ppi[PHYS_SECURE_PPI],
 				arch_timer_evt);
 		if (arch_timer_ppi[PHYS_NONSECURE_PPI])
 			free_percpu_irq(arch_timer_ppi[PHYS_NONSECURE_PPI],
 					arch_timer_evt);
 	}

 out_free:
 	free_percpu(arch_timer_evt);
 out:
 	return err;
 }

 static void __init arch_timer_init(struct device_node *np)
 {
 	u32 freq;
 	int i;

 	if (arch_timer_get_rate()) {
 		pr_warn("arch_timer: multiple nodes in dt, skipping\n");
 		return;
 	}

 	/* Try to determine the frequency from the device tree or CNTFRQ */
 	if (!of_property_read_u32(np, "clock-frequency", &freq))
 		arch_timer_rate = freq;

 	for (i = PHYS_SECURE_PPI; i < MAX_TIMER_PPI; i++)
 		arch_timer_ppi[i] = irq_of_parse_and_map(np, i);

 	of_node_put(np);

 	/*
 	 * If HYP mode is available, we know that the physical timer
 	 * has been configured to be accessible from PL1. Use it, so
 	 * that a guest can use the virtual timer instead.
 	 *
 	 * If no interrupt provided for virtual timer, we'll have to
 	 * stick to the physical timer. It'd better be accessible...
 	 */
 	if (is_hyp_mode_available() || !arch_timer_ppi[VIRT_PPI]) {
 		arch_timer_use_virtual = false;

 		if (!arch_timer_ppi[PHYS_SECURE_PPI] ||
 		    !arch_timer_ppi[PHYS_NONSECURE_PPI]) {
 			pr_warn("arch_timer: No interrupt available, giving up\n");
 			return;
 		}
 	}

 	if (arch_timer_use_virtual)
 		arch_timer_read_counter = arch_counter_get_cntvct;
 	else
 		arch_timer_read_counter = arch_counter_get_cntpct;

 	arch_timer_register();
 	arch_timer_arch_init();
 }
 CLOCKSOURCE_OF_DECLARE(armv7_arch_timer, "arm,armv7-timer", arch_timer_init);
 CLOCKSOURCE_OF_DECLARE(armv8_arch_timer, "arm,armv8-timer", arch_timer_init);
	/*
	* linux/drivers/clocksource/arm_arch_timer.c
	*
	* Copyright (C) 2011 ARM Ltd.
	* All Rights Reserved
	*
	* 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.
	*/
	#include <linux/init.h>
	#include <linux/kernel.h>
	#include <linux/device.h>
	#include <linux/smp.h>
	#include <linux/cpu.h>
	#include <linux/clockchips.h>
	#include <linux/interrupt.h>
	#include <linux/of_irq.h>
	#include <linux/io.h>

	#include <asm/arch_timer.h>
	#include <asm/virt.h>

	#include <clocksource/arm_arch_timer.h>

	static u32 arch_timer_rate;

	enum ppi_nr {
	PHYS_SECURE_PPI,
	PHYS_NONSECURE_PPI,
	VIRT_PPI,
	HYP_PPI,
	MAX_TIMER_PPI
	};

	static int arch_timer_ppi[MAX_TIMER_PPI];

	static struct clock_event_device __percpu *arch_timer_evt;

	static bool arch_timer_use_virtual = true;

	/*
	* Architected system timer support.
	*/

	static inline irqreturn_t timer_handler(const int access,
	struct clock_event_device *evt)
	{
	unsigned long ctrl;
	ctrl = arch_timer_reg_read(access, ARCH_TIMER_REG_CTRL);
	if (ctrl & ARCH_TIMER_CTRL_IT_STAT) {
	ctrl \|= ARCH_TIMER_CTRL_IT_MASK;
	arch_timer_reg_write(access, ARCH_TIMER_REG_CTRL, ctrl);
	evt->event_handler(evt);
	return IRQ_HANDLED;
	}

	return IRQ_NONE;
	}

	static irqreturn_t arch_timer_handler_virt(int irq, void *dev_id)
	{
	struct clock_event_device *evt = dev_id;

	return timer_handler(ARCH_TIMER_VIRT_ACCESS, evt);
	}

	static irqreturn_t arch_timer_handler_phys(int irq, void *dev_id)
	{
	struct clock_event_device *evt = dev_id;

	return timer_handler(ARCH_TIMER_PHYS_ACCESS, evt);
	}

	static inline void timer_set_mode(const int access, int mode)
	{
	unsigned long ctrl;
	switch (mode) {
	case CLOCK_EVT_MODE_UNUSED:
	case CLOCK_EVT_MODE_SHUTDOWN:
	ctrl = arch_timer_reg_read(access, ARCH_TIMER_REG_CTRL);
	ctrl &= ~ARCH_TIMER_CTRL_ENABLE;
	arch_timer_reg_write(access, ARCH_TIMER_REG_CTRL, ctrl);
	break;
	default:
	break;
	}
	}

	static void arch_timer_set_mode_virt(enum clock_event_mode mode,
	struct clock_event_device *clk)
	{
	timer_set_mode(ARCH_TIMER_VIRT_ACCESS, mode);
	}

	static void arch_timer_set_mode_phys(enum clock_event_mode mode,
	struct clock_event_device *clk)
	{
	timer_set_mode(ARCH_TIMER_PHYS_ACCESS, mode);
	}

	static inline void set_next_event(const int access, unsigned long evt)
	{
	unsigned long ctrl;
	ctrl = arch_timer_reg_read(access, ARCH_TIMER_REG_CTRL);
	ctrl \|= ARCH_TIMER_CTRL_ENABLE;
	ctrl &= ~ARCH_TIMER_CTRL_IT_MASK;
	arch_timer_reg_write(access, ARCH_TIMER_REG_TVAL, evt);
	arch_timer_reg_write(access, ARCH_TIMER_REG_CTRL, ctrl);
	}

	static int arch_timer_set_next_event_virt(unsigned long evt,
	struct clock_event_device *unused)
	{
	set_next_event(ARCH_TIMER_VIRT_ACCESS, evt);
	return 0;
	}

	static int arch_timer_set_next_event_phys(unsigned long evt,
	struct clock_event_device *unused)
	{
	set_next_event(ARCH_TIMER_PHYS_ACCESS, evt);
	return 0;
	}

	static int __cpuinit arch_timer_setup(struct clock_event_device *clk)
	{
	clk->features = CLOCK_EVT_FEAT_ONESHOT \| CLOCK_EVT_FEAT_C3STOP;
	clk->name = "arch_sys_timer";
	clk->rating = 450;
	if (arch_timer_use_virtual) {
	clk->irq = arch_timer_ppi[VIRT_PPI];
	clk->set_mode = arch_timer_set_mode_virt;
	clk->set_next_event = arch_timer_set_next_event_virt;
	} else {
	clk->irq = arch_timer_ppi[PHYS_SECURE_PPI];
	clk->set_mode = arch_timer_set_mode_phys;
	clk->set_next_event = arch_timer_set_next_event_phys;
	}

	clk->cpumask = cpumask_of(smp_processor_id());

	clk->set_mode(CLOCK_EVT_MODE_SHUTDOWN, NULL);

	clockevents_config_and_register(clk, arch_timer_rate,
	0xf, 0x7fffffff);

	if (arch_timer_use_virtual)
	enable_percpu_irq(arch_timer_ppi[VIRT_PPI], 0);
	else {
	enable_percpu_irq(arch_timer_ppi[PHYS_SECURE_PPI], 0);
	if (arch_timer_ppi[PHYS_NONSECURE_PPI])
	enable_percpu_irq(arch_timer_ppi[PHYS_NONSECURE_PPI], 0);
	}

	arch_counter_set_user_access();

	return 0;
	}

	static int arch_timer_available(void)
	{
	u32 freq;

	if (arch_timer_rate == 0) {
	freq = arch_timer_get_cntfrq();

	/* Check the timer frequency. */
	if (freq == 0) {
	pr_warn("Architected timer frequency not available\n");
	return -EINVAL;
	}

	arch_timer_rate = freq;
	}

	pr_info_once("Architected local timer running at %lu.%02luMHz (%s).\n",
	(unsigned long)arch_timer_rate / 1000000,
	(unsigned long)(arch_timer_rate / 10000) % 100,
	arch_timer_use_virtual ? "virt" : "phys");
	return 0;
	}

	u32 arch_timer_get_rate(void)
	{
	return arch_timer_rate;
	}

	/*
	* Some external users of arch_timer_read_counter (e.g. sched_clock) may try to
	* call it before it has been initialised. Rather than incur a performance
	* penalty checking for initialisation, provide a default implementation that
	* won't lead to time appearing to jump backwards.
	*/
	static u64 arch_timer_read_zero(void)
	{
	return 0;
	}

	u64 (*arch_timer_read_counter)(void) = arch_timer_read_zero;

	static cycle_t arch_counter_read(struct clocksource *cs)
	{
	return arch_timer_read_counter();
	}

	static cycle_t arch_counter_read_cc(const struct cyclecounter *cc)
	{
	return arch_timer_read_counter();
	}

	static struct clocksource clocksource_counter = {
	.name = "arch_sys_counter",
	.rating = 400,
	.read = arch_counter_read,
	.mask = CLOCKSOURCE_MASK(56),
	.flags = CLOCK_SOURCE_IS_CONTINUOUS,
	};

	static struct cyclecounter cyclecounter = {
	.read = arch_counter_read_cc,
	.mask = CLOCKSOURCE_MASK(56),
	};

	static struct timecounter timecounter;

	struct timecounter *arch_timer_get_timecounter(void)
	{
	return &timecounter;
	}

	static void __cpuinit arch_timer_stop(struct clock_event_device *clk)
	{
	pr_debug("arch_timer_teardown disable IRQ%d cpu #%d\n",
	clk->irq, smp_processor_id());

	if (arch_timer_use_virtual)
	disable_percpu_irq(arch_timer_ppi[VIRT_PPI]);
	else {
	disable_percpu_irq(arch_timer_ppi[PHYS_SECURE_PPI]);
	if (arch_timer_ppi[PHYS_NONSECURE_PPI])
	disable_percpu_irq(arch_timer_ppi[PHYS_NONSECURE_PPI]);
	}

	clk->set_mode(CLOCK_EVT_MODE_UNUSED, clk);
	}

	static int __cpuinit arch_timer_cpu_notify(struct notifier_block *self,
	unsigned long action, void *hcpu)
	{
	/*
	* Grab cpu pointer in each case to avoid spurious
	* preemptible warnings
	*/
	switch (action & ~CPU_TASKS_FROZEN) {
	case CPU_STARTING:
	arch_timer_setup(this_cpu_ptr(arch_timer_evt));
	break;
	case CPU_DYING:
	arch_timer_stop(this_cpu_ptr(arch_timer_evt));
	break;
	}

	return NOTIFY_OK;
	}

	static struct notifier_block arch_timer_cpu_nb __cpuinitdata = {
	.notifier_call = arch_timer_cpu_notify,
	};

	static int __init arch_timer_register(void)
	{
	int err;
	int ppi;

	err = arch_timer_available();
	if (err)
	goto out;

	arch_timer_evt = alloc_percpu(struct clock_event_device);
	if (!arch_timer_evt) {
	err = -ENOMEM;
	goto out;
	}

	clocksource_register_hz(&clocksource_counter, arch_timer_rate);
	cyclecounter.mult = clocksource_counter.mult;
	cyclecounter.shift = clocksource_counter.shift;
	timecounter_init(&timecounter, &cyclecounter,
	arch_counter_get_cntpct());

	if (arch_timer_use_virtual) {
	ppi = arch_timer_ppi[VIRT_PPI];
	err = request_percpu_irq(ppi, arch_timer_handler_virt,
	"arch_timer", arch_timer_evt);
	} else {
	ppi = arch_timer_ppi[PHYS_SECURE_PPI];
	err = request_percpu_irq(ppi, arch_timer_handler_phys,
	"arch_timer", arch_timer_evt);
	if (!err && arch_timer_ppi[PHYS_NONSECURE_PPI]) {
	ppi = arch_timer_ppi[PHYS_NONSECURE_PPI];
	err = request_percpu_irq(ppi, arch_timer_handler_phys,
	"arch_timer", arch_timer_evt);
	if (err)
	free_percpu_irq(arch_timer_ppi[PHYS_SECURE_PPI],
	arch_timer_evt);
	}
	}

	if (err) {
	pr_err("arch_timer: can't register interrupt %d (%d)\n",
	ppi, err);
	goto out_free;
	}

	err = register_cpu_notifier(&arch_timer_cpu_nb);
	if (err)
	goto out_free_irq;

	/* Immediately configure the timer on the boot CPU */
	arch_timer_setup(this_cpu_ptr(arch_timer_evt));

	return 0;

	out_free_irq:
	if (arch_timer_use_virtual)
	free_percpu_irq(arch_timer_ppi[VIRT_PPI], arch_timer_evt);
	else {
	free_percpu_irq(arch_timer_ppi[PHYS_SECURE_PPI],
	arch_timer_evt);
	if (arch_timer_ppi[PHYS_NONSECURE_PPI])
	free_percpu_irq(arch_timer_ppi[PHYS_NONSECURE_PPI],
	arch_timer_evt);
	}

	out_free:
	free_percpu(arch_timer_evt);
	out:
	return err;
	}

	static void __init arch_timer_init(struct device_node *np)
	{
	u32 freq;
	int i;

	if (arch_timer_get_rate()) {
	pr_warn("arch_timer: multiple nodes in dt, skipping\n");
	return;
	}

	/* Try to determine the frequency from the device tree or CNTFRQ */
	if (!of_property_read_u32(np, "clock-frequency", &freq))
	arch_timer_rate = freq;

	for (i = PHYS_SECURE_PPI; i < MAX_TIMER_PPI; i++)
	arch_timer_ppi[i] = irq_of_parse_and_map(np, i);

	of_node_put(np);

	/*
	* If HYP mode is available, we know that the physical timer
	* has been configured to be accessible from PL1. Use it, so
	* that a guest can use the virtual timer instead.
	*
	* If no interrupt provided for virtual timer, we'll have to
	* stick to the physical timer. It'd better be accessible...
	*/
	if (is_hyp_mode_available() \|\| !arch_timer_ppi[VIRT_PPI]) {
	arch_timer_use_virtual = false;

	if (!arch_timer_ppi[PHYS_SECURE_PPI] \|\|
	!arch_timer_ppi[PHYS_NONSECURE_PPI]) {
	pr_warn("arch_timer: No interrupt available, giving up\n");
	return;
	}
	}

	if (arch_timer_use_virtual)
	arch_timer_read_counter = arch_counter_get_cntvct;
	else
	arch_timer_read_counter = arch_counter_get_cntpct;

	arch_timer_register();
	arch_timer_arch_init();
	}
	CLOCKSOURCE_OF_DECLARE(armv7_arch_timer, "arm,armv7-timer", arch_timer_init);
	CLOCKSOURCE_OF_DECLARE(armv8_arch_timer, "arm,armv8-timer", arch_timer_init);