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1da177e4 LT |
1 | /* defines for inline arch setup functions */ |
2 | ||
3 | #include <asm/apic.h> | |
4 | ||
5 | /** | |
6 | * do_timer_interrupt_hook - hook into timer tick | |
7 | * @regs: standard registers from interrupt | |
8 | * | |
9 | * Description: | |
10 | * This hook is called immediately after the timer interrupt is ack'd. | |
11 | * It's primary purpose is to allow architectures that don't possess | |
12 | * individual per CPU clocks (like the CPU APICs supply) to broadcast the | |
13 | * timer interrupt as a means of triggering reschedules etc. | |
14 | **/ | |
15 | ||
16 | static inline void do_timer_interrupt_hook(struct pt_regs *regs) | |
17 | { | |
18 | do_timer(regs); | |
19 | #ifndef CONFIG_SMP | |
20 | update_process_times(user_mode(regs)); | |
21 | #endif | |
22 | /* | |
23 | * In the SMP case we use the local APIC timer interrupt to do the | |
24 | * profiling, except when we simulate SMP mode on a uniprocessor | |
25 | * system, in that case we have to call the local interrupt handler. | |
26 | */ | |
27 | #ifndef CONFIG_X86_LOCAL_APIC | |
28 | profile_tick(CPU_PROFILING, regs); | |
29 | #else | |
30 | if (!using_apic_timer) | |
31 | smp_local_timer_interrupt(regs); | |
32 | #endif | |
33 | } | |
34 | ||
35 | ||
36 | /* you can safely undefine this if you don't have the Neptune chipset */ | |
37 | ||
38 | #define BUGGY_NEPTUN_TIMER | |
39 | ||
40 | /** | |
41 | * do_timer_overflow - process a detected timer overflow condition | |
42 | * @count: hardware timer interrupt count on overflow | |
43 | * | |
44 | * Description: | |
45 | * This call is invoked when the jiffies count has not incremented but | |
46 | * the hardware timer interrupt has. It means that a timer tick interrupt | |
47 | * came along while the previous one was pending, thus a tick was missed | |
48 | **/ | |
49 | static inline int do_timer_overflow(int count) | |
50 | { | |
51 | int i; | |
52 | ||
53 | spin_lock(&i8259A_lock); | |
54 | /* | |
55 | * This is tricky when I/O APICs are used; | |
56 | * see do_timer_interrupt(). | |
57 | */ | |
58 | i = inb(0x20); | |
59 | spin_unlock(&i8259A_lock); | |
60 | ||
61 | /* assumption about timer being IRQ0 */ | |
62 | if (i & 0x01) { | |
63 | /* | |
64 | * We cannot detect lost timer interrupts ... | |
65 | * well, that's why we call them lost, don't we? :) | |
66 | * [hmm, on the Pentium and Alpha we can ... sort of] | |
67 | */ | |
68 | count -= LATCH; | |
69 | } else { | |
70 | #ifdef BUGGY_NEPTUN_TIMER | |
71 | /* | |
72 | * for the Neptun bug we know that the 'latch' | |
73 | * command doesn't latch the high and low value | |
74 | * of the counter atomically. Thus we have to | |
75 | * substract 256 from the counter | |
76 | * ... funny, isnt it? :) | |
77 | */ | |
78 | ||
79 | count -= 256; | |
80 | #else | |
81 | printk("do_slow_gettimeoffset(): hardware timer problem?\n"); | |
82 | #endif | |
83 | } | |
84 | return count; | |
85 | } |