Merge branch 'for-2.6.22' of git://git.kernel.dk/data/git/linux-2.6-block
[linux-2.6] / arch / arm / mach-imx / time.c
1 /*
2  *  linux/arch/arm/mach-imx/time.c
3  *
4  *  Copyright (C) 2000-2001 Deep Blue Solutions
5  *  Copyright (C) 2002 Shane Nay (shane@minirl.com)
6  *
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.
10  */
11 #include <linux/kernel.h>
12 #include <linux/sched.h>
13 #include <linux/init.h>
14 #include <linux/interrupt.h>
15 #include <linux/irq.h>
16 #include <linux/time.h>
17 #include <linux/clocksource.h>
18
19 #include <asm/hardware.h>
20 #include <asm/io.h>
21 #include <asm/leds.h>
22 #include <asm/irq.h>
23 #include <asm/mach/time.h>
24
25 /* Use timer 1 as system timer */
26 #define TIMER_BASE IMX_TIM1_BASE
27
28 static unsigned long evt_diff;
29
30 /*
31  * IRQ handler for the timer
32  */
33 static irqreturn_t
34 imx_timer_interrupt(int irq, void *dev_id)
35 {
36         uint32_t tstat;
37
38         /* clear the interrupt */
39         tstat = IMX_TSTAT(TIMER_BASE);
40         IMX_TSTAT(TIMER_BASE) = 0;
41
42         if (tstat & TSTAT_COMP) {
43                 do {
44
45                         write_seqlock(&xtime_lock);
46                         timer_tick();
47                         write_sequnlock(&xtime_lock);
48                         IMX_TCMP(TIMER_BASE) += evt_diff;
49
50                 } while (unlikely((int32_t)(IMX_TCMP(TIMER_BASE)
51                                         - IMX_TCN(TIMER_BASE)) < 0));
52         }
53
54         return IRQ_HANDLED;
55 }
56
57 static struct irqaction imx_timer_irq = {
58         .name           = "i.MX Timer Tick",
59         .flags          = IRQF_DISABLED | IRQF_TIMER | IRQF_IRQPOLL,
60         .handler        = imx_timer_interrupt,
61 };
62
63 /*
64  * Set up timer hardware into expected mode and state.
65  */
66 static void __init imx_timer_hardware_init(void)
67 {
68         /*
69          * Initialise to a known state (all timers off, and timing reset)
70          */
71         IMX_TCTL(TIMER_BASE) = 0;
72         IMX_TPRER(TIMER_BASE) = 0;
73         IMX_TCMP(TIMER_BASE) = LATCH - 1;
74
75         IMX_TCTL(TIMER_BASE) = TCTL_FRR | TCTL_CLK_PCLK1 | TCTL_IRQEN | TCTL_TEN;
76         evt_diff = LATCH;
77 }
78
79 cycle_t imx_get_cycles(void)
80 {
81         return IMX_TCN(TIMER_BASE);
82 }
83
84 static struct clocksource clocksource_imx = {
85         .name           = "imx_timer1",
86         .rating         = 200,
87         .read           = imx_get_cycles,
88         .mask           = 0xFFFFFFFF,
89         .shift          = 20,
90         .flags          = CLOCK_SOURCE_IS_CONTINUOUS,
91 };
92
93 static int __init imx_clocksource_init(void)
94 {
95         clocksource_imx.mult =
96                 clocksource_hz2mult(imx_get_perclk1(), clocksource_imx.shift);
97         clocksource_register(&clocksource_imx);
98
99         return 0;
100 }
101
102 static void __init imx_timer_init(void)
103 {
104         imx_timer_hardware_init();
105         imx_clocksource_init();
106
107         /*
108          * Make irqs happen for the system timer
109          */
110         setup_irq(TIM1_INT, &imx_timer_irq);
111 }
112
113 struct sys_timer imx_timer = {
114         .init           = imx_timer_init,
115 };