aboutsummaryrefslogtreecommitdiff
path: root/arch/arm/mach-realview/localtimer.c
blob: 504961ef343c2ef0f0e6be6bc052b997d90405fd (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
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
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
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
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
/*
 *  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>
#include <linux/jiffies.h>
#include <linux/percpu.h>
#include <linux/clockchips.h>
#include <linux/irq.h>
#include <linux/io.h>

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

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

#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;

static unsigned long mpcore_timer_rate;

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;
}

/*
 * local_timer_ack: checks for a local timer interrupt.
 *
 * If a local timer interrupt has occurred, acknowledge and return 1.
 * 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;
}

static void __cpuinit twd_calibrate_rate(unsigned int cpu)
{
	void __iomem *base = TWD_BASE(cpu);
	unsigned long load, count;
	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);
}

/*
 * 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;

	twd_calibrate_rate(cpu);

	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);
	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);

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

	clockevents_register_device(clk);
}

/*
 * take a local timer down
 */
void __cpuexit local_timer_stop(unsigned int cpu)
{
	__raw_writel(0, TWD_BASE(cpu) + TWD_TIMER_CONTROL);
}

#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);

	clockevents_register_device(clk);
}

#endif	/* !CONFIG_LOCAL_TIMERS */