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>
21 #include <asm/hardware/arm_twd.h>
22 #include <asm/hardware/gic.h>
23 #include <asm/hardware.h>
27 #define TWD_BASE(cpu) (__io_address(REALVIEW_TWD_BASE) + \
28 ((cpu) * REALVIEW_TWD_SIZE))
30 static DEFINE_PER_CPU(struct clock_event_device, local_clockevent);
33 * Used on SMP for either the local timer or IPI_TIMER
35 void local_timer_interrupt(void)
37 struct clock_event_device *clk = &__get_cpu_var(local_clockevent);
39 clk->event_handler(clk);
42 #ifdef CONFIG_LOCAL_TIMERS
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)
49 void __iomem *base = TWD_BASE(smp_processor_id());
53 case CLOCK_EVT_MODE_PERIODIC:
54 /* timer load already set up */
55 ctrl = TWD_TIMER_CONTROL_ENABLE | TWD_TIMER_CONTROL_IT_ENABLE
56 | TWD_TIMER_CONTROL_PERIODIC;
58 case CLOCK_EVT_MODE_ONESHOT:
59 /* period set, and timer enabled in 'next_event' hook */
60 ctrl = TWD_TIMER_CONTROL_IT_ENABLE | TWD_TIMER_CONTROL_ONESHOT;
62 case CLOCK_EVT_MODE_UNUSED:
63 case CLOCK_EVT_MODE_SHUTDOWN:
68 __raw_writel(ctrl, base + TWD_TIMER_CONTROL);
71 static int local_timer_set_next_event(unsigned long evt,
72 struct clock_event_device *unused)
74 void __iomem *base = TWD_BASE(smp_processor_id());
75 unsigned long ctrl = __raw_readl(base + TWD_TIMER_CONTROL);
77 __raw_writel(evt, base + TWD_TIMER_COUNTER);
78 __raw_writel(ctrl | TWD_TIMER_CONTROL_ENABLE, base + TWD_TIMER_CONTROL);
84 * local_timer_ack: checks for a local timer interrupt.
86 * If a local timer interrupt has occurred, acknowledge and return 1.
87 * Otherwise, return 0.
89 int local_timer_ack(void)
91 void __iomem *base = TWD_BASE(smp_processor_id());
93 if (__raw_readl(base + TWD_TIMER_INTSTAT)) {
94 __raw_writel(1, base + TWD_TIMER_INTSTAT);
101 static void __cpuinit twd_calibrate_rate(unsigned int cpu)
103 void __iomem *base = TWD_BASE(cpu);
104 unsigned long load, count;
108 * If this is the first time round, we need to work out how fast
111 if (mpcore_timer_rate == 0) {
112 printk("Calibrating local timer... ");
114 /* Wait for a tick to start */
115 waitjiffies = get_jiffies_64() + 1;
117 while (get_jiffies_64() < waitjiffies)
120 /* OK, now the tick has started, let's get the timer going */
123 /* enable, no interrupt or reload */
124 __raw_writel(0x1, base + TWD_TIMER_CONTROL);
127 __raw_writel(0xFFFFFFFFU, base + TWD_TIMER_COUNTER);
129 while (get_jiffies_64() < waitjiffies)
132 count = __raw_readl(base + TWD_TIMER_COUNTER);
134 mpcore_timer_rate = (0xFFFFFFFFU - count) * (HZ / 5);
136 printk("%lu.%02luMHz.\n", mpcore_timer_rate / 1000000,
137 (mpcore_timer_rate / 100000) % 100);
140 load = mpcore_timer_rate / HZ;
142 __raw_writel(load, base + TWD_TIMER_LOAD);
146 * Setup the local clock events for a CPU.
148 void __cpuinit local_timer_setup(unsigned int cpu)
150 struct clock_event_device *clk = &per_cpu(local_clockevent, cpu);
153 twd_calibrate_rate(cpu);
155 clk->name = "local_timer";
156 clk->features = CLOCK_EVT_FEAT_PERIODIC | CLOCK_EVT_FEAT_ONESHOT;
158 clk->set_mode = local_timer_set_mode;
159 clk->set_next_event = local_timer_set_next_event;
160 clk->irq = IRQ_LOCALTIMER;
161 clk->cpumask = cpumask_of_cpu(cpu);
163 clk->mult = div_sc(mpcore_timer_rate, NSEC_PER_SEC, clk->shift);
164 clk->max_delta_ns = clockevent_delta2ns(0xffffffff, clk);
165 clk->min_delta_ns = clockevent_delta2ns(0xf, clk);
167 /* Make sure our local interrupt controller has this enabled */
168 local_irq_save(flags);
169 get_irq_chip(IRQ_LOCALTIMER)->unmask(IRQ_LOCALTIMER);
170 local_irq_restore(flags);
172 clockevents_register_device(clk);
176 * take a local timer down
178 void __cpuexit local_timer_stop(unsigned int cpu)
180 __raw_writel(0, TWD_BASE(cpu) + TWD_TIMER_CONTROL);
183 #else /* CONFIG_LOCAL_TIMERS */
185 static void dummy_timer_set_mode(enum clock_event_mode mode,
186 struct clock_event_device *clk)
190 void __cpuinit local_timer_setup(unsigned int cpu)
192 struct clock_event_device *clk = &per_cpu(local_clockevent, cpu);
194 clk->name = "dummy_timer";
195 clk->features = CLOCK_EVT_FEAT_DUMMY;
197 clk->set_mode = dummy_timer_set_mode;
198 clk->broadcast = smp_timer_broadcast;
199 clk->cpumask = cpumask_of_cpu(cpu);
201 clockevents_register_device(clk);
204 #endif /* !CONFIG_LOCAL_TIMERS */