diff options
Diffstat (limited to 'arch/i386/kernel/timers/timer_pit.c')
| -rw-r--r-- | arch/i386/kernel/timers/timer_pit.c | 177 |
1 files changed, 0 insertions, 177 deletions
diff --git a/arch/i386/kernel/timers/timer_pit.c b/arch/i386/kernel/timers/timer_pit.c deleted file mode 100644 index b9b6bd56b9b..00000000000 --- a/arch/i386/kernel/timers/timer_pit.c +++ /dev/null @@ -1,177 +0,0 @@ -/* - * This code largely moved from arch/i386/kernel/time.c. - * See comments there for proper credits. - */ - -#include <linux/spinlock.h> -#include <linux/module.h> -#include <linux/device.h> -#include <linux/sysdev.h> -#include <linux/timex.h> -#include <asm/delay.h> -#include <asm/mpspec.h> -#include <asm/timer.h> -#include <asm/smp.h> -#include <asm/io.h> -#include <asm/arch_hooks.h> -#include <asm/i8253.h> - -#include "do_timer.h" -#include "io_ports.h" - -static int count_p; /* counter in get_offset_pit() */ - -static int __init init_pit(char* override) -{ - /* check clock override */ - if (override[0] && strncmp(override,"pit",3)) - printk(KERN_ERR "Warning: clock= override failed. Defaulting " - "to PIT\n"); - init_cpu_khz(); - count_p = LATCH; - return 0; -} - -static void mark_offset_pit(void) -{ - /* nothing needed */ -} - -static unsigned long long monotonic_clock_pit(void) -{ - return 0; -} - -static void delay_pit(unsigned long loops) -{ - int d0; - __asm__ __volatile__( - "\tjmp 1f\n" - ".align 16\n" - "1:\tjmp 2f\n" - ".align 16\n" - "2:\tdecl %0\n\tjns 2b" - :"=&a" (d0) - :"0" (loops)); -} - - -/* This function must be called with xtime_lock held. - * It was inspired by Steve McCanne's microtime-i386 for BSD. -- jrs - * - * However, the pc-audio speaker driver changes the divisor so that - * it gets interrupted rather more often - it loads 64 into the - * counter rather than 11932! This has an adverse impact on - * do_gettimeoffset() -- it stops working! What is also not - * good is that the interval that our timer function gets called - * is no longer 10.0002 ms, but 9.9767 ms. To get around this - * would require using a different timing source. Maybe someone - * could use the RTC - I know that this can interrupt at frequencies - * ranging from 8192Hz to 2Hz. If I had the energy, I'd somehow fix - * it so that at startup, the timer code in sched.c would select - * using either the RTC or the 8253 timer. The decision would be - * based on whether there was any other device around that needed - * to trample on the 8253. I'd set up the RTC to interrupt at 1024 Hz, - * and then do some jiggery to have a version of do_timer that - * advanced the clock by 1/1024 s. Every time that reached over 1/100 - * of a second, then do all the old code. If the time was kept correct - * then do_gettimeoffset could just return 0 - there is no low order - * divider that can be accessed. - * - * Ideally, you would be able to use the RTC for the speaker driver, - * but it appears that the speaker driver really needs interrupt more - * often than every 120 us or so. - * - * Anyway, this needs more thought.... pjsg (1993-08-28) - * - * If you are really that interested, you should be reading - * comp.protocols.time.ntp! - */ - -static unsigned long get_offset_pit(void) -{ - int count; - unsigned long flags; - static unsigned long jiffies_p = 0; - - /* - * cache volatile jiffies temporarily; we have xtime_lock. - */ - unsigned long jiffies_t; - - spin_lock_irqsave(&i8253_lock, flags); - /* timer count may underflow right here */ - outb_p(0x00, PIT_MODE); /* latch the count ASAP */ - - count = inb_p(PIT_CH0); /* read the latched count */ - - /* - * We do this guaranteed double memory access instead of a _p - * postfix in the previous port access. Wheee, hackady hack - */ - jiffies_t = jiffies; - - count |= inb_p(PIT_CH0) << 8; - - /* VIA686a test code... reset the latch if count > max + 1 */ - if (count > LATCH) { - outb_p(0x34, PIT_MODE); - outb_p(LATCH & 0xff, PIT_CH0); - outb(LATCH >> 8, PIT_CH0); - count = LATCH - 1; - } - - /* - * avoiding timer inconsistencies (they are rare, but they happen)... - * there are two kinds of problems that must be avoided here: - * 1. the timer counter underflows - * 2. hardware problem with the timer, not giving us continuous time, - * the counter does small "jumps" upwards on some Pentium systems, - * (see c't 95/10 page 335 for Neptun bug.) - */ - - if( jiffies_t == jiffies_p ) { - if( count > count_p ) { - /* the nutcase */ - count = do_timer_overflow(count); - } - } else - jiffies_p = jiffies_t; - - count_p = count; - - spin_unlock_irqrestore(&i8253_lock, flags); - - count = ((LATCH-1) - count) * TICK_SIZE; - count = (count + LATCH/2) / LATCH; - - return count; -} - - -/* tsc timer_opts struct */ -struct timer_opts timer_pit = { - .name = "pit", - .mark_offset = mark_offset_pit, - .get_offset = get_offset_pit, - .monotonic_clock = monotonic_clock_pit, - .delay = delay_pit, -}; - -struct init_timer_opts __initdata timer_pit_init = { - .init = init_pit, - .opts = &timer_pit, -}; - -void setup_pit_timer(void) -{ - unsigned long flags; - - spin_lock_irqsave(&i8253_lock, flags); - outb_p(0x34,PIT_MODE); /* binary, mode 2, LSB/MSB, ch 0 */ - udelay(10); - outb_p(LATCH & 0xff , PIT_CH0); /* LSB */ - udelay(10); - outb(LATCH >> 8 , PIT_CH0); /* MSB */ - spin_unlock_irqrestore(&i8253_lock, flags); -} |