localtimer.c 5.03 KB
Newer Older
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
/*
 *  linux/arch/arm/mach-realview/localtimer.c
 *
 *  Copyright (C) 2002 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/delay.h>
#include <linux/device.h>
#include <linux/smp.h>
16
#include <linux/jiffies.h>
17 18
#include <linux/percpu.h>
#include <linux/clockchips.h>
19
#include <linux/irq.h>
20
#include <linux/io.h>
21 22 23

#include <asm/hardware/arm_twd.h>
#include <asm/hardware/gic.h>
24
#include <mach/hardware.h>
25 26
#include <asm/irq.h>

27 28 29 30 31 32 33 34 35 36 37 38 39 40
static DEFINE_PER_CPU(struct clock_event_device, local_clockevent);

/*
 * Used on SMP for either the local timer or IPI_TIMER
 */
void local_timer_interrupt(void)
{
	struct clock_event_device *clk = &__get_cpu_var(local_clockevent);

	clk->event_handler(clk);
}

#ifdef CONFIG_LOCAL_TIMERS

41 42 43 44 45 46
#define TWD_BASE(cpu)	(twd_base_addr + (cpu) * twd_size)

/* set up by the platform code */
void __iomem *twd_base_addr;
unsigned int twd_size;

47 48
static unsigned long mpcore_timer_rate;

49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85
static void local_timer_set_mode(enum clock_event_mode mode,
				 struct clock_event_device *clk)
{
	void __iomem *base = TWD_BASE(smp_processor_id());
	unsigned long ctrl;

	switch(mode) {
	case CLOCK_EVT_MODE_PERIODIC:
		/* timer load already set up */
		ctrl = TWD_TIMER_CONTROL_ENABLE | TWD_TIMER_CONTROL_IT_ENABLE
			| TWD_TIMER_CONTROL_PERIODIC;
		break;
	case CLOCK_EVT_MODE_ONESHOT:
		/* period set, and timer enabled in 'next_event' hook */
		ctrl = TWD_TIMER_CONTROL_IT_ENABLE | TWD_TIMER_CONTROL_ONESHOT;
		break;
	case CLOCK_EVT_MODE_UNUSED:
	case CLOCK_EVT_MODE_SHUTDOWN:
	default:
		ctrl = 0;
	}

	__raw_writel(ctrl, base + TWD_TIMER_CONTROL);
}

static int local_timer_set_next_event(unsigned long evt,
				      struct clock_event_device *unused)
{
	void __iomem *base = TWD_BASE(smp_processor_id());
	unsigned long ctrl = __raw_readl(base + TWD_TIMER_CONTROL);

	__raw_writel(evt, base + TWD_TIMER_COUNTER);
	__raw_writel(ctrl | TWD_TIMER_CONTROL_ENABLE, base + TWD_TIMER_CONTROL);

	return 0;
}

86 87 88
/*
 * local_timer_ack: checks for a local timer interrupt.
 *
Simon Arlott's avatar
Simon Arlott committed
89
 * If a local timer interrupt has occurred, acknowledge and return 1.
90 91 92 93 94 95 96 97 98 99 100 101 102 103
 * Otherwise, return 0.
 */
int local_timer_ack(void)
{
	void __iomem *base = TWD_BASE(smp_processor_id());

	if (__raw_readl(base + TWD_TIMER_INTSTAT)) {
		__raw_writel(1, base + TWD_TIMER_INTSTAT);
		return 1;
	}

	return 0;
}

104
static void __cpuinit twd_calibrate_rate(unsigned int cpu)
105 106
{
	void __iomem *base = TWD_BASE(cpu);
107
	unsigned long load, count;
108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145
	u64 waitjiffies;

	/*
	 * If this is the first time round, we need to work out how fast
	 * the timer ticks
	 */
	if (mpcore_timer_rate == 0) {
		printk("Calibrating local timer... ");

		/* Wait for a tick to start */
		waitjiffies = get_jiffies_64() + 1;

		while (get_jiffies_64() < waitjiffies)
			udelay(10);

		/* OK, now the tick has started, let's get the timer going */
		waitjiffies += 5;

				 /* enable, no interrupt or reload */
		__raw_writel(0x1, base + TWD_TIMER_CONTROL);

				 /* maximum value */
		__raw_writel(0xFFFFFFFFU, base + TWD_TIMER_COUNTER);

		while (get_jiffies_64() < waitjiffies)
			udelay(10);

		count = __raw_readl(base + TWD_TIMER_COUNTER);

		mpcore_timer_rate = (0xFFFFFFFFU - count) * (HZ / 5);

		printk("%lu.%02luMHz.\n", mpcore_timer_rate / 1000000,
			(mpcore_timer_rate / 100000) % 100);
	}

	load = mpcore_timer_rate / HZ;

	__raw_writel(load, base + TWD_TIMER_LOAD);
146
}
147

148 149 150 151 152 153 154
/*
 * Setup the local clock events for a CPU.
 */
void __cpuinit local_timer_setup(unsigned int cpu)
{
	struct clock_event_device *clk = &per_cpu(local_clockevent, cpu);
	unsigned long flags;
155

156
	twd_calibrate_rate(cpu);
157

158 159 160 161 162 163 164 165 166 167 168
	clk->name		= "local_timer";
	clk->features		= CLOCK_EVT_FEAT_PERIODIC | CLOCK_EVT_FEAT_ONESHOT;
	clk->rating		= 350;
	clk->set_mode		= local_timer_set_mode;
	clk->set_next_event	= local_timer_set_next_event;
	clk->irq		= IRQ_LOCALTIMER;
	clk->cpumask		= cpumask_of_cpu(cpu);
	clk->shift		= 20;
	clk->mult		= div_sc(mpcore_timer_rate, NSEC_PER_SEC, clk->shift);
	clk->max_delta_ns	= clockevent_delta2ns(0xffffffff, clk);
	clk->min_delta_ns	= clockevent_delta2ns(0xf, clk);
169 170

	/* Make sure our local interrupt controller has this enabled */
171 172 173 174 175
	local_irq_save(flags);
	get_irq_chip(IRQ_LOCALTIMER)->unmask(IRQ_LOCALTIMER);
	local_irq_restore(flags);

	clockevents_register_device(clk);
176 177 178 179 180 181 182 183 184
}

/*
 * take a local timer down
 */
void __cpuexit local_timer_stop(unsigned int cpu)
{
	__raw_writel(0, TWD_BASE(cpu) + TWD_TIMER_CONTROL);
}
185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207

#else	/* CONFIG_LOCAL_TIMERS */

static void dummy_timer_set_mode(enum clock_event_mode mode,
				 struct clock_event_device *clk)
{
}

void __cpuinit local_timer_setup(unsigned int cpu)
{
	struct clock_event_device *clk = &per_cpu(local_clockevent, cpu);

	clk->name		= "dummy_timer";
	clk->features		= CLOCK_EVT_FEAT_DUMMY;
	clk->rating		= 200;
	clk->set_mode		= dummy_timer_set_mode;
	clk->broadcast		= smp_timer_broadcast;
	clk->cpumask		= cpumask_of_cpu(cpu);

	clockevents_register_device(clk);
}

#endif	/* !CONFIG_LOCAL_TIMERS */