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