From 798778b8653f64b7b2162ac70eca10367cff6ce8 Mon Sep 17 00:00:00 2001 From: Russell King Date: Sun, 8 May 2011 19:03:03 +0100 Subject: [PATCH] clocksource: convert mips to generic i8253 clocksource Convert MIPS i8253 clocksource code to use generic i8253 clocksource. Acked-by: John Stultz Acked-by: Thomas Gleixner Cc: Ralf Baechle Signed-off-by: Russell King --- arch/mips/Kconfig | 1 + arch/mips/include/asm/i8253.h | 5 +++ arch/mips/kernel/i8253.c | 78 +---------------------------------- 3 files changed, 7 insertions(+), 77 deletions(-) diff --git a/arch/mips/Kconfig b/arch/mips/Kconfig index 8e256cc5dcd9..f7f6419e4c84 100644 --- a/arch/mips/Kconfig +++ b/arch/mips/Kconfig @@ -2339,6 +2339,7 @@ config MMU config I8253 bool + select CLKSRC_I8253 select MIPS_EXTERNAL_TIMER config ZONE_DMA32 diff --git a/arch/mips/include/asm/i8253.h b/arch/mips/include/asm/i8253.h index 48bb82372994..9ad011366f73 100644 --- a/arch/mips/include/asm/i8253.h +++ b/arch/mips/include/asm/i8253.h @@ -12,8 +12,13 @@ #define PIT_CH0 0x40 #define PIT_CH2 0x42 +#define PIT_LATCH LATCH + extern raw_spinlock_t i8253_lock; extern void setup_pit_timer(void); +#define inb_pit inb_p +#define outb_pit outb_p + #endif /* __ASM_I8253_H */ diff --git a/arch/mips/kernel/i8253.c b/arch/mips/kernel/i8253.c index 2392a7a296d4..391221b6a6aa 100644 --- a/arch/mips/kernel/i8253.c +++ b/arch/mips/kernel/i8253.c @@ -125,87 +125,11 @@ void __init setup_pit_timer(void) setup_irq(0, &irq0); } -/* - * Since the PIT overflows every tick, its not very useful - * to just read by itself. So use jiffies to emulate a free - * running counter: - */ -static cycle_t pit_read(struct clocksource *cs) -{ - unsigned long flags; - int count; - u32 jifs; - static int old_count; - static u32 old_jifs; - - raw_spin_lock_irqsave(&i8253_lock, flags); - /* - * Although our caller may have the read side of xtime_lock, - * this is now a seqlock, and we are cheating in this routine - * by having side effects on state that we cannot undo if - * there is a collision on the seqlock and our caller has to - * retry. (Namely, old_jifs and old_count.) So we must treat - * jiffies as volatile despite the lock. We read jiffies - * before latching the timer count to guarantee that although - * the jiffies value might be older than the count (that is, - * the counter may underflow between the last point where - * jiffies was incremented and the point where we latch the - * count), it cannot be newer. - */ - jifs = jiffies; - outb_p(0x00, PIT_MODE); /* latch the count ASAP */ - count = inb_p(PIT_CH0); /* read the latched count */ - 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; - } - - /* - * It's possible for count to appear to go the wrong way for a - * couple of reasons: - * - * 1. The timer counter underflows, but we haven't handled the - * resulting interrupt and incremented jiffies yet. - * 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.) - * - * Previous attempts to handle these cases intelligently were - * buggy, so we just do the simple thing now. - */ - if (count > old_count && jifs == old_jifs) { - count = old_count; - } - old_count = count; - old_jifs = jifs; - - raw_spin_unlock_irqrestore(&i8253_lock, flags); - - count = (LATCH - 1) - count; - - return (cycle_t)(jifs * LATCH) + count; -} - -static struct clocksource clocksource_pit = { - .name = "pit", - .rating = 110, - .read = pit_read, - .mask = CLOCKSOURCE_MASK(32), - .mult = 0, - .shift = 20, -}; - static int __init init_pit_clocksource(void) { if (num_possible_cpus() > 1) /* PIT does not scale! */ return 0; - clocksource_pit.mult = clocksource_hz2mult(CLOCK_TICK_RATE, 20); - return clocksource_register(&clocksource_pit); + return clocksource_i8253_init(); } arch_initcall(init_pit_clocksource); -- 2.30.2