drivers/clocksource/timer-tegra.c - linux/torvalds/linux - Git at Google

 // SPDX-License-Identifier: GPL-2.0-only
 /*
  * Copyright (C) 2010 Google, Inc.
  *
  * Author:
  *	Colin Cross <ccross@google.com>
  */

 #define pr_fmt(fmt)	"tegra-timer: " fmt

 #include <linux/clk.h>
 #include <linux/clockchips.h>
 #include <linux/cpu.h>
 #include <linux/cpumask.h>
 #include <linux/delay.h>
 #include <linux/err.h>
 #include <linux/interrupt.h>
 #include <linux/of_address.h>
 #include <linux/of_irq.h>
 #include <linux/percpu.h>
 #include <linux/sched_clock.h>
 #include <linux/time.h>

 #include "timer-of.h"

 #define RTC_SECONDS		0x08
 #define RTC_SHADOW_SECONDS	0x0c
 #define RTC_MILLISECONDS	0x10

 #define TIMERUS_CNTR_1US	0x10
 #define TIMERUS_USEC_CFG	0x14
 #define TIMERUS_CNTR_FREEZE	0x4c

 #define TIMER_PTV		0x0
 #define TIMER_PTV_EN		BIT(31)
 #define TIMER_PTV_PER		BIT(30)
 #define TIMER_PCR		0x4
 #define TIMER_PCR_INTR_CLR	BIT(30)

 #define TIMER1_BASE		0x00
 #define TIMER2_BASE		0x08
 #define TIMER3_BASE		0x50
 #define TIMER4_BASE		0x58
 #define TIMER10_BASE		0x90

 #define TIMER1_IRQ_IDX		0
 #define TIMER10_IRQ_IDX		10

 #define TIMER_1MHz		1000000

 static u32 usec_config;
 static void __iomem *timer_reg_base;

 static int tegra_timer_set_next_event(unsigned long cycles,
 				      struct clock_event_device *evt)
 {
 	void __iomem *reg_base = timer_of_base(to_timer_of(evt));

 	/*
 	 * Tegra's timer uses n+1 scheme for the counter, i.e. timer will
 	 * fire after one tick if 0 is loaded.
 	 *
 	 * The minimum and maximum numbers of oneshot ticks are defined
 	 * by clockevents_config_and_register(1, 0x1fffffff + 1) invocation
 	 * below in the code. Hence the cycles (ticks) can't be outside of
 	 * a range supportable by hardware.
 	 */
 	writel_relaxed(TIMER_PTV_EN | (cycles - 1), reg_base + TIMER_PTV);

 	return 0;
 }

 static int tegra_timer_shutdown(struct clock_event_device *evt)
 {
 	void __iomem *reg_base = timer_of_base(to_timer_of(evt));

 	writel_relaxed(0, reg_base + TIMER_PTV);

 	return 0;
 }

 static int tegra_timer_set_periodic(struct clock_event_device *evt)
 {
 	void __iomem *reg_base = timer_of_base(to_timer_of(evt));
 	unsigned long period = timer_of_period(to_timer_of(evt));

 	writel_relaxed(TIMER_PTV_EN | TIMER_PTV_PER | (period - 1),
 		       reg_base + TIMER_PTV);

 	return 0;
 }

 static irqreturn_t tegra_timer_isr(int irq, void *dev_id)
 {
 	struct clock_event_device *evt = dev_id;
 	void __iomem *reg_base = timer_of_base(to_timer_of(evt));

 	writel_relaxed(TIMER_PCR_INTR_CLR, reg_base + TIMER_PCR);
 	evt->event_handler(evt);

 	return IRQ_HANDLED;
 }

 static void tegra_timer_suspend(struct clock_event_device *evt)
 {
 	void __iomem *reg_base = timer_of_base(to_timer_of(evt));

 	writel_relaxed(TIMER_PCR_INTR_CLR, reg_base + TIMER_PCR);
 }

 static void tegra_timer_resume(struct clock_event_device *evt)
 {
 	writel_relaxed(usec_config, timer_reg_base + TIMERUS_USEC_CFG);
 }

 static DEFINE_PER_CPU(struct timer_of, tegra_to) = {
 	.flags = TIMER_OF_CLOCK | TIMER_OF_BASE,

 	.clkevt = {
 		.name = "tegra_timer",
 		.features = CLOCK_EVT_FEAT_ONESHOT | CLOCK_EVT_FEAT_PERIODIC,
 		.set_next_event = tegra_timer_set_next_event,
 		.set_state_shutdown = tegra_timer_shutdown,
 		.set_state_periodic = tegra_timer_set_periodic,
 		.set_state_oneshot = tegra_timer_shutdown,
 		.tick_resume = tegra_timer_shutdown,
 		.suspend = tegra_timer_suspend,
 		.resume = tegra_timer_resume,
 	},
 };

 static int tegra_timer_setup(unsigned int cpu)
 {
 	struct timer_of *to = per_cpu_ptr(&tegra_to, cpu);

 	writel_relaxed(0, timer_of_base(to) + TIMER_PTV);
 	writel_relaxed(TIMER_PCR_INTR_CLR, timer_of_base(to) + TIMER_PCR);

 	irq_force_affinity(to->clkevt.irq, cpumask_of(cpu));
 	enable_irq(to->clkevt.irq);

 	/*
 	 * Tegra's timer uses n+1 scheme for the counter, i.e. timer will
 	 * fire after one tick if 0 is loaded and thus minimum number of
 	 * ticks is 1. In result both of the clocksource's tick limits are
 	 * higher than a minimum and maximum that hardware register can
 	 * take by 1, this is then taken into account by set_next_event
 	 * callback.
 	 */
 	clockevents_config_and_register(&to->clkevt, timer_of_rate(to),
 					1, /* min */
 					0x1fffffff + 1); /* max 29 bits + 1 */

 	return 0;
 }

 static int tegra_timer_stop(unsigned int cpu)
 {
 	struct timer_of *to = per_cpu_ptr(&tegra_to, cpu);

 	to->clkevt.set_state_shutdown(&to->clkevt);
 	disable_irq_nosync(to->clkevt.irq);

 	return 0;
 }

 static u64 notrace tegra_read_sched_clock(void)
 {
 	return readl_relaxed(timer_reg_base + TIMERUS_CNTR_1US);
 }

 #ifdef CONFIG_ARM
 static unsigned long tegra_delay_timer_read_counter_long(void)
 {
 	return readl_relaxed(timer_reg_base + TIMERUS_CNTR_1US);
 }

 static struct delay_timer tegra_delay_timer = {
 	.read_current_timer = tegra_delay_timer_read_counter_long,
 	.freq = TIMER_1MHz,
 };
 #endif

 static struct timer_of suspend_rtc_to = {
 	.flags = TIMER_OF_BASE | TIMER_OF_CLOCK,
 };

 /*
  * tegra_rtc_read - Reads the Tegra RTC registers
  * Care must be taken that this function is not called while the
  * tegra_rtc driver could be executing to avoid race conditions
  * on the RTC shadow register
  */
 static u64 tegra_rtc_read_ms(struct clocksource *cs)
 {
 	void __iomem *reg_base = timer_of_base(&suspend_rtc_to);

 	u32 ms = readl_relaxed(reg_base + RTC_MILLISECONDS);
 	u32 s = readl_relaxed(reg_base + RTC_SHADOW_SECONDS);

 	return (u64)s * MSEC_PER_SEC + ms;
 }

 static struct clocksource suspend_rtc_clocksource = {
 	.name	= "tegra_suspend_timer",
 	.rating	= 200,
 	.read	= tegra_rtc_read_ms,
 	.mask	= CLOCKSOURCE_MASK(32),
 	.flags	= CLOCK_SOURCE_IS_CONTINUOUS | CLOCK_SOURCE_SUSPEND_NONSTOP,
 };

 static inline unsigned int tegra_base_for_cpu(int cpu, bool tegra20)
 {
 	if (tegra20) {
 		switch (cpu) {
 		case 0:
 			return TIMER1_BASE;
 		case 1:
 			return TIMER2_BASE;
 		case 2:
 			return TIMER3_BASE;
 		default:
 			return TIMER4_BASE;
 		}
 	}

 	return TIMER10_BASE + cpu * 8;
 }

 static inline unsigned int tegra_irq_idx_for_cpu(int cpu, bool tegra20)
 {
 	if (tegra20)
 		return TIMER1_IRQ_IDX + cpu;

 	return TIMER10_IRQ_IDX + cpu;
 }

 static inline unsigned long tegra_rate_for_timer(struct timer_of *to,
 						 bool tegra20)
 {
 	/*
 	 * TIMER1-9 are fixed to 1MHz, TIMER10-13 are running off the
 	 * parent clock.
 	 */
 	if (tegra20)
 		return TIMER_1MHz;

 	return timer_of_rate(to);
 }

 static int __init tegra_init_timer(struct device_node *np, bool tegra20,
 				   int rating)
 {
 	struct timer_of *to;
 	int cpu, ret;

 	to = this_cpu_ptr(&tegra_to);
 	ret = timer_of_init(np, to);
 	if (ret)
 		goto out;

 	timer_reg_base = timer_of_base(to);

 	/*
 	 * Configure microsecond timers to have 1MHz clock
 	 * Config register is 0xqqww, where qq is "dividend", ww is "divisor"
 	 * Uses n+1 scheme
 	 */
 	switch (timer_of_rate(to)) {
 	case 12000000:
 		usec_config = 0x000b; /* (11+1)/(0+1) */
 		break;
 	case 12800000:
 		usec_config = 0x043f; /* (63+1)/(4+1) */
 		break;
 	case 13000000:
 		usec_config = 0x000c; /* (12+1)/(0+1) */
 		break;
 	case 16800000:
 		usec_config = 0x0453; /* (83+1)/(4+1) */
 		break;
 	case 19200000:
 		usec_config = 0x045f; /* (95+1)/(4+1) */
 		break;
 	case 26000000:
 		usec_config = 0x0019; /* (25+1)/(0+1) */
 		break;
 	case 38400000:
 		usec_config = 0x04bf; /* (191+1)/(4+1) */
 		break;
 	case 48000000:
 		usec_config = 0x002f; /* (47+1)/(0+1) */
 		break;
 	default:
 		ret = -EINVAL;
 		goto out;
 	}

 	writel_relaxed(usec_config, timer_reg_base + TIMERUS_USEC_CFG);

 	for_each_possible_cpu(cpu) {
 		struct timer_of *cpu_to = per_cpu_ptr(&tegra_to, cpu);
 		unsigned long flags = IRQF_TIMER | IRQF_NOBALANCING;
 		unsigned long rate = tegra_rate_for_timer(to, tegra20);
 		unsigned int base = tegra_base_for_cpu(cpu, tegra20);
 		unsigned int idx = tegra_irq_idx_for_cpu(cpu, tegra20);
 		unsigned int irq = irq_of_parse_and_map(np, idx);

 		if (!irq) {
 			pr_err("failed to map irq for cpu%d\n", cpu);
 			ret = -EINVAL;
 			goto out_irq;
 		}

 		cpu_to->clkevt.irq = irq;
 		cpu_to->clkevt.rating = rating;
 		cpu_to->clkevt.cpumask = cpumask_of(cpu);
 		cpu_to->of_base.base = timer_reg_base + base;
 		cpu_to->of_clk.period = rate / HZ;
 		cpu_to->of_clk.rate = rate;

 		irq_set_status_flags(cpu_to->clkevt.irq, IRQ_NOAUTOEN);

 		ret = request_irq(cpu_to->clkevt.irq, tegra_timer_isr, flags,
 				  cpu_to->clkevt.name, &cpu_to->clkevt);
 		if (ret) {
 			pr_err("failed to set up irq for cpu%d: %d\n",
 			       cpu, ret);
 			irq_dispose_mapping(cpu_to->clkevt.irq);
 			cpu_to->clkevt.irq = 0;
 			goto out_irq;
 		}
 	}

 	sched_clock_register(tegra_read_sched_clock, 32, TIMER_1MHz);

 	ret = clocksource_mmio_init(timer_reg_base + TIMERUS_CNTR_1US,
 				    "timer_us", TIMER_1MHz, 300, 32,
 				    clocksource_mmio_readl_up);
 	if (ret)
 		pr_err("failed to register clocksource: %d\n", ret);

 #ifdef CONFIG_ARM
 	register_current_timer_delay(&tegra_delay_timer);
 #endif

 	ret = cpuhp_setup_state(CPUHP_AP_TEGRA_TIMER_STARTING,
 				"AP_TEGRA_TIMER_STARTING", tegra_timer_setup,
 				tegra_timer_stop);
 	if (ret)
 		pr_err("failed to set up cpu hp state: %d\n", ret);

 	return ret;

 out_irq:
 	for_each_possible_cpu(cpu) {
 		struct timer_of *cpu_to;

 		cpu_to = per_cpu_ptr(&tegra_to, cpu);
 		if (cpu_to->clkevt.irq) {
 			free_irq(cpu_to->clkevt.irq, &cpu_to->clkevt);
 			irq_dispose_mapping(cpu_to->clkevt.irq);
 		}
 	}

 	to->of_base.base = timer_reg_base;
 out:
 	timer_of_cleanup(to);

 	return ret;
 }

 static int __init tegra210_init_timer(struct device_node *np)
 {
 	/*
 	 * Arch-timer can't survive across power cycle of CPU core and
 	 * after CPUPORESET signal due to a system design shortcoming,
 	 * hence tegra-timer is more preferable on Tegra210.
 	 */
 	return tegra_init_timer(np, false, 460);
 }
 TIMER_OF_DECLARE(tegra210_timer, "nvidia,tegra210-timer", tegra210_init_timer);

 static int __init tegra20_init_timer(struct device_node *np)
 {
 	int rating;

 	/*
 	 * Tegra20 and Tegra30 have Cortex A9 CPU that has a TWD timer,
 	 * that timer runs off the CPU clock and hence is subjected to
 	 * a jitter caused by DVFS clock rate changes. Tegra-timer is
 	 * more preferable for older Tegra's, while later SoC generations
 	 * have arch-timer as a main per-CPU timer and it is not affected
 	 * by DVFS changes.
 	 */
 	if (of_machine_is_compatible("nvidia,tegra20") ||
 	    of_machine_is_compatible("nvidia,tegra30"))
 		rating = 460;
 	else
 		rating = 330;

 	return tegra_init_timer(np, true, rating);
 }
 TIMER_OF_DECLARE(tegra20_timer, "nvidia,tegra20-timer", tegra20_init_timer);

 static int __init tegra20_init_rtc(struct device_node *np)
 {
 	int ret;

 	ret = timer_of_init(np, &suspend_rtc_to);
 	if (ret)
 		return ret;

 	return clocksource_register_hz(&suspend_rtc_clocksource, 1000);
 }
 TIMER_OF_DECLARE(tegra20_rtc, "nvidia,tegra20-rtc", tegra20_init_rtc);
	// SPDX-License-Identifier: GPL-2.0-only
	/*
	* Copyright (C) 2010 Google, Inc.
	*
	* Author:
	* Colin Cross <ccross@google.com>
	*/

	#define pr_fmt(fmt) "tegra-timer: " fmt

	#include <linux/clk.h>
	#include <linux/clockchips.h>
	#include <linux/cpu.h>
	#include <linux/cpumask.h>
	#include <linux/delay.h>
	#include <linux/err.h>
	#include <linux/interrupt.h>
	#include <linux/of_address.h>
	#include <linux/of_irq.h>
	#include <linux/percpu.h>
	#include <linux/sched_clock.h>
	#include <linux/time.h>

	#include "timer-of.h"

	#define RTC_SECONDS 0x08
	#define RTC_SHADOW_SECONDS 0x0c
	#define RTC_MILLISECONDS 0x10

	#define TIMERUS_CNTR_1US 0x10
	#define TIMERUS_USEC_CFG 0x14
	#define TIMERUS_CNTR_FREEZE 0x4c

	#define TIMER_PTV 0x0
	#define TIMER_PTV_EN BIT(31)
	#define TIMER_PTV_PER BIT(30)
	#define TIMER_PCR 0x4
	#define TIMER_PCR_INTR_CLR BIT(30)

	#define TIMER1_BASE 0x00
	#define TIMER2_BASE 0x08
	#define TIMER3_BASE 0x50
	#define TIMER4_BASE 0x58
	#define TIMER10_BASE 0x90

	#define TIMER1_IRQ_IDX 0
	#define TIMER10_IRQ_IDX 10

	#define TIMER_1MHz 1000000

	static u32 usec_config;
	static void __iomem *timer_reg_base;

	static int tegra_timer_set_next_event(unsigned long cycles,
	struct clock_event_device *evt)
	{
	void __iomem *reg_base = timer_of_base(to_timer_of(evt));

	/*
	* Tegra's timer uses n+1 scheme for the counter, i.e. timer will
	* fire after one tick if 0 is loaded.
	*
	* The minimum and maximum numbers of oneshot ticks are defined
	* by clockevents_config_and_register(1, 0x1fffffff + 1) invocation
	* below in the code. Hence the cycles (ticks) can't be outside of
	* a range supportable by hardware.
	*/
	writel_relaxed(TIMER_PTV_EN \| (cycles - 1), reg_base + TIMER_PTV);

	return 0;
	}

	static int tegra_timer_shutdown(struct clock_event_device *evt)
	{
	void __iomem *reg_base = timer_of_base(to_timer_of(evt));

	writel_relaxed(0, reg_base + TIMER_PTV);

	return 0;
	}

	static int tegra_timer_set_periodic(struct clock_event_device *evt)
	{
	void __iomem *reg_base = timer_of_base(to_timer_of(evt));
	unsigned long period = timer_of_period(to_timer_of(evt));

	writel_relaxed(TIMER_PTV_EN \| TIMER_PTV_PER \| (period - 1),
	reg_base + TIMER_PTV);

	return 0;
	}

	static irqreturn_t tegra_timer_isr(int irq, void *dev_id)
	{
	struct clock_event_device *evt = dev_id;
	void __iomem *reg_base = timer_of_base(to_timer_of(evt));

	writel_relaxed(TIMER_PCR_INTR_CLR, reg_base + TIMER_PCR);
	evt->event_handler(evt);

	return IRQ_HANDLED;
	}

	static void tegra_timer_suspend(struct clock_event_device *evt)
	{
	void __iomem *reg_base = timer_of_base(to_timer_of(evt));

	writel_relaxed(TIMER_PCR_INTR_CLR, reg_base + TIMER_PCR);
	}

	static void tegra_timer_resume(struct clock_event_device *evt)
	{
	writel_relaxed(usec_config, timer_reg_base + TIMERUS_USEC_CFG);
	}

	static DEFINE_PER_CPU(struct timer_of, tegra_to) = {
	.flags = TIMER_OF_CLOCK \| TIMER_OF_BASE,

	.clkevt = {
	.name = "tegra_timer",
	.features = CLOCK_EVT_FEAT_ONESHOT \| CLOCK_EVT_FEAT_PERIODIC,
	.set_next_event = tegra_timer_set_next_event,
	.set_state_shutdown = tegra_timer_shutdown,
	.set_state_periodic = tegra_timer_set_periodic,
	.set_state_oneshot = tegra_timer_shutdown,
	.tick_resume = tegra_timer_shutdown,
	.suspend = tegra_timer_suspend,
	.resume = tegra_timer_resume,
	},
	};

	static int tegra_timer_setup(unsigned int cpu)
	{
	struct timer_of *to = per_cpu_ptr(&tegra_to, cpu);

	writel_relaxed(0, timer_of_base(to) + TIMER_PTV);
	writel_relaxed(TIMER_PCR_INTR_CLR, timer_of_base(to) + TIMER_PCR);

	irq_force_affinity(to->clkevt.irq, cpumask_of(cpu));
	enable_irq(to->clkevt.irq);

	/*
	* Tegra's timer uses n+1 scheme for the counter, i.e. timer will
	* fire after one tick if 0 is loaded and thus minimum number of
	* ticks is 1. In result both of the clocksource's tick limits are
	* higher than a minimum and maximum that hardware register can
	* take by 1, this is then taken into account by set_next_event
	* callback.
	*/
	clockevents_config_and_register(&to->clkevt, timer_of_rate(to),
	1, /* min */
	0x1fffffff + 1); /* max 29 bits + 1 */

	return 0;
	}

	static int tegra_timer_stop(unsigned int cpu)
	{
	struct timer_of *to = per_cpu_ptr(&tegra_to, cpu);

	to->clkevt.set_state_shutdown(&to->clkevt);
	disable_irq_nosync(to->clkevt.irq);

	return 0;
	}

	static u64 notrace tegra_read_sched_clock(void)
	{
	return readl_relaxed(timer_reg_base + TIMERUS_CNTR_1US);
	}

	#ifdef CONFIG_ARM
	static unsigned long tegra_delay_timer_read_counter_long(void)
	{
	return readl_relaxed(timer_reg_base + TIMERUS_CNTR_1US);
	}

	static struct delay_timer tegra_delay_timer = {
	.read_current_timer = tegra_delay_timer_read_counter_long,
	.freq = TIMER_1MHz,
	};
	#endif

	static struct timer_of suspend_rtc_to = {
	.flags = TIMER_OF_BASE \| TIMER_OF_CLOCK,
	};

	/*
	* tegra_rtc_read - Reads the Tegra RTC registers
	* Care must be taken that this function is not called while the
	* tegra_rtc driver could be executing to avoid race conditions
	* on the RTC shadow register
	*/
	static u64 tegra_rtc_read_ms(struct clocksource *cs)
	{
	void __iomem *reg_base = timer_of_base(&suspend_rtc_to);

	u32 ms = readl_relaxed(reg_base + RTC_MILLISECONDS);
	u32 s = readl_relaxed(reg_base + RTC_SHADOW_SECONDS);

	return (u64)s * MSEC_PER_SEC + ms;
	}

	static struct clocksource suspend_rtc_clocksource = {
	.name = "tegra_suspend_timer",
	.rating = 200,
	.read = tegra_rtc_read_ms,
	.mask = CLOCKSOURCE_MASK(32),
	.flags = CLOCK_SOURCE_IS_CONTINUOUS \| CLOCK_SOURCE_SUSPEND_NONSTOP,
	};

	static inline unsigned int tegra_base_for_cpu(int cpu, bool tegra20)
	{
	if (tegra20) {
	switch (cpu) {
	case 0:
	return TIMER1_BASE;
	case 1:
	return TIMER2_BASE;
	case 2:
	return TIMER3_BASE;
	default:
	return TIMER4_BASE;
	}
	}

	return TIMER10_BASE + cpu * 8;
	}

	static inline unsigned int tegra_irq_idx_for_cpu(int cpu, bool tegra20)
	{
	if (tegra20)
	return TIMER1_IRQ_IDX + cpu;

	return TIMER10_IRQ_IDX + cpu;
	}

	static inline unsigned long tegra_rate_for_timer(struct timer_of *to,
	bool tegra20)
	{
	/*
	* TIMER1-9 are fixed to 1MHz, TIMER10-13 are running off the
	* parent clock.
	*/
	if (tegra20)
	return TIMER_1MHz;

	return timer_of_rate(to);
	}

	static int __init tegra_init_timer(struct device_node *np, bool tegra20,
	int rating)
	{
	struct timer_of *to;
	int cpu, ret;

	to = this_cpu_ptr(&tegra_to);
	ret = timer_of_init(np, to);
	if (ret)
	goto out;

	timer_reg_base = timer_of_base(to);

	/*
	* Configure microsecond timers to have 1MHz clock
	* Config register is 0xqqww, where qq is "dividend", ww is "divisor"
	* Uses n+1 scheme
	*/
	switch (timer_of_rate(to)) {
	case 12000000:
	usec_config = 0x000b; /* (11+1)/(0+1) */
	break;
	case 12800000:
	usec_config = 0x043f; /* (63+1)/(4+1) */
	break;
	case 13000000:
	usec_config = 0x000c; /* (12+1)/(0+1) */
	break;
	case 16800000:
	usec_config = 0x0453; /* (83+1)/(4+1) */
	break;
	case 19200000:
	usec_config = 0x045f; /* (95+1)/(4+1) */
	break;
	case 26000000:
	usec_config = 0x0019; /* (25+1)/(0+1) */
	break;
	case 38400000:
	usec_config = 0x04bf; /* (191+1)/(4+1) */
	break;
	case 48000000:
	usec_config = 0x002f; /* (47+1)/(0+1) */
	break;
	default:
	ret = -EINVAL;
	goto out;
	}

	writel_relaxed(usec_config, timer_reg_base + TIMERUS_USEC_CFG);

	for_each_possible_cpu(cpu) {
	struct timer_of *cpu_to = per_cpu_ptr(&tegra_to, cpu);
	unsigned long flags = IRQF_TIMER \| IRQF_NOBALANCING;
	unsigned long rate = tegra_rate_for_timer(to, tegra20);
	unsigned int base = tegra_base_for_cpu(cpu, tegra20);
	unsigned int idx = tegra_irq_idx_for_cpu(cpu, tegra20);
	unsigned int irq = irq_of_parse_and_map(np, idx);

	if (!irq) {
	pr_err("failed to map irq for cpu%d\n", cpu);
	ret = -EINVAL;
	goto out_irq;
	}

	cpu_to->clkevt.irq = irq;
	cpu_to->clkevt.rating = rating;
	cpu_to->clkevt.cpumask = cpumask_of(cpu);
	cpu_to->of_base.base = timer_reg_base + base;
	cpu_to->of_clk.period = rate / HZ;
	cpu_to->of_clk.rate = rate;

	irq_set_status_flags(cpu_to->clkevt.irq, IRQ_NOAUTOEN);

	ret = request_irq(cpu_to->clkevt.irq, tegra_timer_isr, flags,
	cpu_to->clkevt.name, &cpu_to->clkevt);
	if (ret) {
	pr_err("failed to set up irq for cpu%d: %d\n",
	cpu, ret);
	irq_dispose_mapping(cpu_to->clkevt.irq);
	cpu_to->clkevt.irq = 0;
	goto out_irq;
	}
	}

	sched_clock_register(tegra_read_sched_clock, 32, TIMER_1MHz);

	ret = clocksource_mmio_init(timer_reg_base + TIMERUS_CNTR_1US,
	"timer_us", TIMER_1MHz, 300, 32,
	clocksource_mmio_readl_up);
	if (ret)
	pr_err("failed to register clocksource: %d\n", ret);

	#ifdef CONFIG_ARM
	register_current_timer_delay(&tegra_delay_timer);
	#endif

	ret = cpuhp_setup_state(CPUHP_AP_TEGRA_TIMER_STARTING,
	"AP_TEGRA_TIMER_STARTING", tegra_timer_setup,
	tegra_timer_stop);
	if (ret)
	pr_err("failed to set up cpu hp state: %d\n", ret);

	return ret;

	out_irq:
	for_each_possible_cpu(cpu) {
	struct timer_of *cpu_to;

	cpu_to = per_cpu_ptr(&tegra_to, cpu);
	if (cpu_to->clkevt.irq) {
	free_irq(cpu_to->clkevt.irq, &cpu_to->clkevt);
	irq_dispose_mapping(cpu_to->clkevt.irq);
	}
	}

	to->of_base.base = timer_reg_base;
	out:
	timer_of_cleanup(to);

	return ret;
	}

	static int __init tegra210_init_timer(struct device_node *np)
	{
	/*
	* Arch-timer can't survive across power cycle of CPU core and
	* after CPUPORESET signal due to a system design shortcoming,
	* hence tegra-timer is more preferable on Tegra210.
	*/
	return tegra_init_timer(np, false, 460);
	}
	TIMER_OF_DECLARE(tegra210_timer, "nvidia,tegra210-timer", tegra210_init_timer);

	static int __init tegra20_init_timer(struct device_node *np)
	{
	int rating;

	/*
	* Tegra20 and Tegra30 have Cortex A9 CPU that has a TWD timer,
	* that timer runs off the CPU clock and hence is subjected to
	* a jitter caused by DVFS clock rate changes. Tegra-timer is
	* more preferable for older Tegra's, while later SoC generations
	* have arch-timer as a main per-CPU timer and it is not affected
	* by DVFS changes.
	*/
	if (of_machine_is_compatible("nvidia,tegra20") \|\|
	of_machine_is_compatible("nvidia,tegra30"))
	rating = 460;
	else
	rating = 330;

	return tegra_init_timer(np, true, rating);
	}
	TIMER_OF_DECLARE(tegra20_timer, "nvidia,tegra20-timer", tegra20_init_timer);

	static int __init tegra20_init_rtc(struct device_node *np)
	{
	int ret;

	ret = timer_of_init(np, &suspend_rtc_to);
	if (ret)
	return ret;

	return clocksource_register_hz(&suspend_rtc_clocksource, 1000);
	}
	TIMER_OF_DECLARE(tegra20_rtc, "nvidia,tegra20-rtc", tegra20_init_rtc);