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
);
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_ONESHOT
|
193 CLOCK_EVT_FEAT_PERIODIC
|
194 CLOCK_EVT_FEAT_DUMMY
;
197 clk
->set_mode
= dummy_timer_set_mode
;
198 clk
->broadcast
= smp_timer_broadcast
;
199 clk
->cpumask
= cpumask_of(cpu
);
201 clockevents_register_device(clk
);
204 #endif /* !CONFIG_LOCAL_TIMERS */