| Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame^] | 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 | } |