diff options
Diffstat (limited to 'arch/i386/kernel/hpet.c')
| -rw-r--r-- | arch/i386/kernel/hpet.c | 80 |
1 files changed, 37 insertions, 43 deletions
diff --git a/arch/i386/kernel/hpet.c b/arch/i386/kernel/hpet.c index e1006b7acc9e..f3ab61ee7498 100644 --- a/arch/i386/kernel/hpet.c +++ b/arch/i386/kernel/hpet.c @@ -201,12 +201,30 @@ static int hpet_next_event(unsigned long delta, } /* + * Clock source related code + */ +static cycle_t read_hpet(void) +{ + return (cycle_t)hpet_readl(HPET_COUNTER); +} + +static struct clocksource clocksource_hpet = { + .name = "hpet", + .rating = 250, + .read = read_hpet, + .mask = HPET_MASK, + .shift = HPET_SHIFT, + .flags = CLOCK_SOURCE_IS_CONTINUOUS, +}; + +/* * Try to setup the HPET timer */ int __init hpet_enable(void) { unsigned long id; uint64_t hpet_freq; + u64 tmp; if (!is_hpet_capable()) return 0; @@ -253,6 +271,25 @@ int __init hpet_enable(void) /* Start the counter */ hpet_start_counter(); + /* Initialize and register HPET clocksource + * + * hpet period is in femto seconds per cycle + * so we need to convert this to ns/cyc units + * aproximated by mult/2^shift + * + * fsec/cyc * 1nsec/1000000fsec = nsec/cyc = mult/2^shift + * fsec/cyc * 1ns/1000000fsec * 2^shift = mult + * fsec/cyc * 2^shift * 1nsec/1000000fsec = mult + * (fsec/cyc << shift)/1000000 = mult + * (hpet_period << shift)/FSEC_PER_NSEC = mult + */ + tmp = (u64)hpet_period << HPET_SHIFT; + do_div(tmp, FSEC_PER_NSEC); + clocksource_hpet.mult = (u32)tmp; + + clocksource_register(&clocksource_hpet); + + if (id & HPET_ID_LEGSUP) { hpet_enable_int(); hpet_reserve_platform_timers(id); @@ -273,49 +310,6 @@ out_nohpet: return 0; } -/* - * Clock source related code - */ -static cycle_t read_hpet(void) -{ - return (cycle_t)hpet_readl(HPET_COUNTER); -} - -static struct clocksource clocksource_hpet = { - .name = "hpet", - .rating = 250, - .read = read_hpet, - .mask = HPET_MASK, - .shift = HPET_SHIFT, - .flags = CLOCK_SOURCE_IS_CONTINUOUS, -}; - -static int __init init_hpet_clocksource(void) -{ - u64 tmp; - - if (!hpet_virt_address) - return -ENODEV; - - /* - * hpet period is in femto seconds per cycle - * so we need to convert this to ns/cyc units - * aproximated by mult/2^shift - * - * fsec/cyc * 1nsec/1000000fsec = nsec/cyc = mult/2^shift - * fsec/cyc * 1ns/1000000fsec * 2^shift = mult - * fsec/cyc * 2^shift * 1nsec/1000000fsec = mult - * (fsec/cyc << shift)/1000000 = mult - * (hpet_period << shift)/FSEC_PER_NSEC = mult - */ - tmp = (u64)hpet_period << HPET_SHIFT; - do_div(tmp, FSEC_PER_NSEC); - clocksource_hpet.mult = (u32)tmp; - - return clocksource_register(&clocksource_hpet); -} - -module_init(init_hpet_clocksource); #ifdef CONFIG_HPET_EMULATE_RTC |