2 * linux/arch/arm/mach-realview/localtimer.c
4 * Copyright (C) 2002 ARM Ltd.
7 * This program is free software; you can redistribute it and/or modify
8 * it under the terms of the GNU General Public License version 2 as
9 * published by the Free Software Foundation.
11 #include <linux/init.h>
12 #include <linux/kernel.h>
13 #include <linux/delay.h>
14 #include <linux/device.h>
15 #include <linux/smp.h>
16 #include <linux/jiffies.h>
17 #include <linux/percpu.h>
18 #include <linux/clockchips.h>
19 #include <linux/irq.h>
22 #include <asm/hardware/arm_twd.h>
23 #include <asm/hardware/gic.h>
24 #include <mach/hardware.h>
27 static DEFINE_PER_CPU(struct clock_event_device, local_clockevent);
30 * Used on SMP for either the local timer or IPI_TIMER
32 void local_timer_interrupt(void)
34 struct clock_event_device *clk = &__get_cpu_var(local_clockevent);
36 clk->event_handler(clk);
39 #ifdef CONFIG_LOCAL_TIMERS
41 /* set up by the platform code */
42 void __iomem *twd_base;
44 static unsigned long mpcore_timer_rate;
46 static void local_timer_set_mode(enum clock_event_mode mode,
47 struct clock_event_device *clk)
52 case CLOCK_EVT_MODE_PERIODIC:
53 /* timer load already set up */
54 ctrl = TWD_TIMER_CONTROL_ENABLE | TWD_TIMER_CONTROL_IT_ENABLE
55 | TWD_TIMER_CONTROL_PERIODIC;
57 case CLOCK_EVT_MODE_ONESHOT:
58 /* period set, and timer enabled in 'next_event' hook */
59 ctrl = TWD_TIMER_CONTROL_IT_ENABLE | TWD_TIMER_CONTROL_ONESHOT;
61 case CLOCK_EVT_MODE_UNUSED:
62 case CLOCK_EVT_MODE_SHUTDOWN:
67 __raw_writel(ctrl, twd_base + TWD_TIMER_CONTROL);
70 static int local_timer_set_next_event(unsigned long evt,
71 struct clock_event_device *unused)
73 unsigned long ctrl = __raw_readl(twd_base + TWD_TIMER_CONTROL);
75 __raw_writel(evt, twd_base + TWD_TIMER_COUNTER);
76 __raw_writel(ctrl | TWD_TIMER_CONTROL_ENABLE, twd_base + TWD_TIMER_CONTROL);
82 * local_timer_ack: checks for a local timer interrupt.
84 * If a local timer interrupt has occurred, acknowledge and return 1.
85 * Otherwise, return 0.
87 int local_timer_ack(void)
89 if (__raw_readl(twd_base + TWD_TIMER_INTSTAT)) {
90 __raw_writel(1, twd_base + TWD_TIMER_INTSTAT);
97 static void __cpuinit twd_calibrate_rate(void)
99 unsigned long load, count;
103 * If this is the first time round, we need to work out how fast
106 if (mpcore_timer_rate == 0) {
107 printk("Calibrating local timer... ");
109 /* Wait for a tick to start */
110 waitjiffies = get_jiffies_64() + 1;
112 while (get_jiffies_64() < waitjiffies)
115 /* OK, now the tick has started, let's get the timer going */
118 /* enable, no interrupt or reload */
119 __raw_writel(0x1, twd_base + TWD_TIMER_CONTROL);
122 __raw_writel(0xFFFFFFFFU, twd_base + TWD_TIMER_COUNTER);
124 while (get_jiffies_64() < waitjiffies)
127 count = __raw_readl(twd_base + TWD_TIMER_COUNTER);
129 mpcore_timer_rate = (0xFFFFFFFFU - count) * (HZ / 5);
131 printk("%lu.%02luMHz.\n", mpcore_timer_rate / 1000000,
132 (mpcore_timer_rate / 100000) % 100);
135 load = mpcore_timer_rate / HZ;
137 __raw_writel(load, twd_base + TWD_TIMER_LOAD);
141 * Setup the local clock events for a CPU.
143 void __cpuinit local_timer_setup(void)
145 unsigned int cpu = smp_processor_id();
146 struct clock_event_device *clk = &per_cpu(local_clockevent, cpu);
149 twd_calibrate_rate();
151 clk->name = "local_timer";
152 clk->features = CLOCK_EVT_FEAT_PERIODIC | CLOCK_EVT_FEAT_ONESHOT;
154 clk->set_mode = local_timer_set_mode;
155 clk->set_next_event = local_timer_set_next_event;
156 clk->irq = IRQ_LOCALTIMER;
157 clk->cpumask = cpumask_of_cpu(cpu);
159 clk->mult = div_sc(mpcore_timer_rate, NSEC_PER_SEC, clk->shift);
160 clk->max_delta_ns = clockevent_delta2ns(0xffffffff, clk);
161 clk->min_delta_ns = clockevent_delta2ns(0xf, clk);
163 /* Make sure our local interrupt controller has this enabled */
164 local_irq_save(flags);
165 get_irq_chip(IRQ_LOCALTIMER)->unmask(IRQ_LOCALTIMER);
166 local_irq_restore(flags);
168 clockevents_register_device(clk);
172 * take a local timer down
174 void __cpuexit local_timer_stop(void)
176 __raw_writel(0, twd_base + TWD_TIMER_CONTROL);
179 #else /* CONFIG_LOCAL_TIMERS */
181 static void dummy_timer_set_mode(enum clock_event_mode mode,
182 struct clock_event_device *clk)
186 void __cpuinit local_timer_setup(void)
188 unsigned int cpu = smp_processor_id();
189 struct clock_event_device *clk = &per_cpu(local_clockevent, cpu);
191 clk->name = "dummy_timer";
192 clk->features = CLOCK_EVT_FEAT_DUMMY;
194 clk->set_mode = dummy_timer_set_mode;
195 clk->broadcast = smp_timer_broadcast;
196 clk->cpumask = cpumask_of_cpu(cpu);
198 clockevents_register_device(clk);
201 #endif /* !CONFIG_LOCAL_TIMERS */