blob: 56211414fc9595bc1aeb7a854e1133b6e5238036 (
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
|
/* defines for inline arch setup functions */
#include <asm/apic.h>
#include <asm/i8259.h>
/**
* do_timer_interrupt_hook - hook into timer tick
* @regs: standard registers from interrupt
*
* Description:
* This hook is called immediately after the timer interrupt is ack'd.
* It's primary purpose is to allow architectures that don't possess
* individual per CPU clocks (like the CPU APICs supply) to broadcast the
* timer interrupt as a means of triggering reschedules etc.
**/
static inline void do_timer_interrupt_hook(struct pt_regs *regs)
{
do_timer(regs);
#ifndef CONFIG_SMP
update_process_times(user_mode(regs));
#endif
/*
* In the SMP case we use the local APIC timer interrupt to do the
* profiling, except when we simulate SMP mode on a uniprocessor
* system, in that case we have to call the local interrupt handler.
*/
#ifndef CONFIG_X86_LOCAL_APIC
profile_tick(CPU_PROFILING, regs);
#else
if (!using_apic_timer)
smp_local_timer_interrupt(regs);
#endif
}
/* you can safely undefine this if you don't have the Neptune chipset */
#define BUGGY_NEPTUN_TIMER
/**
* do_timer_overflow - process a detected timer overflow condition
* @count: hardware timer interrupt count on overflow
*
* Description:
* This call is invoked when the jiffies count has not incremented but
* the hardware timer interrupt has. It means that a timer tick interrupt
* came along while the previous one was pending, thus a tick was missed
**/
static inline int do_timer_overflow(int count)
{
int i;
spin_lock(&i8259A_lock);
/*
* This is tricky when I/O APICs are used;
* see do_timer_interrupt().
*/
i = inb(0x20);
spin_unlock(&i8259A_lock);
/* assumption about timer being IRQ0 */
if (i & 0x01) {
/*
* We cannot detect lost timer interrupts ...
* well, that's why we call them lost, don't we? :)
* [hmm, on the Pentium and Alpha we can ... sort of]
*/
count -= LATCH;
} else {
#ifdef BUGGY_NEPTUN_TIMER
/*
* for the Neptun bug we know that the 'latch'
* command doesn't latch the high and low value
* of the counter atomically. Thus we have to
* substract 256 from the counter
* ... funny, isnt it? :)
*/
count -= 256;
#else
printk("do_slow_gettimeoffset(): hardware timer problem?\n");
#endif
}
return count;
}
|
