diff options
Diffstat (limited to 'arch/x86_64/kernel/hpet.c')
| -rw-r--r-- | arch/x86_64/kernel/hpet.c | 109 |
1 files changed, 44 insertions, 65 deletions
diff --git a/arch/x86_64/kernel/hpet.c b/arch/x86_64/kernel/hpet.c index 65a0edd71a1..8cf0b8a1377 100644 --- a/arch/x86_64/kernel/hpet.c +++ b/arch/x86_64/kernel/hpet.c @@ -12,6 +12,12 @@ #include <asm/timex.h> #include <asm/hpet.h> +#define HPET_MASK 0xFFFFFFFF +#define HPET_SHIFT 22 + +/* FSEC = 10^-15 NSEC = 10^-9 */ +#define FSEC_PER_NSEC 1000000 + int nohpet __initdata; unsigned long hpet_address; @@ -106,9 +112,31 @@ int hpet_timer_stop_set_go(unsigned long tick) return 0; } +static cycle_t read_hpet(void) +{ + return (cycle_t)hpet_readl(HPET_COUNTER); +} + +static cycle_t __vsyscall_fn vread_hpet(void) +{ + return readl((void __iomem *)fix_to_virt(VSYSCALL_HPET) + 0xf0); +} + +struct clocksource clocksource_hpet = { + .name = "hpet", + .rating = 250, + .read = read_hpet, + .mask = (cycle_t)HPET_MASK, + .mult = 0, /* set below */ + .shift = HPET_SHIFT, + .flags = CLOCK_SOURCE_IS_CONTINUOUS, + .vread = vread_hpet, +}; + int hpet_arch_init(void) { unsigned int id; + u64 tmp; if (!hpet_address) return -1; @@ -132,6 +160,22 @@ int hpet_arch_init(void) hpet_use_timer = (id & HPET_ID_LEGSUP); + /* + * 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); + return hpet_timer_stop_set_go(hpet_tick); } @@ -444,68 +488,3 @@ static int __init nohpet_setup(char *s) } __setup("nohpet", nohpet_setup); - -#define HPET_MASK 0xFFFFFFFF -#define HPET_SHIFT 22 - -/* FSEC = 10^-15 NSEC = 10^-9 */ -#define FSEC_PER_NSEC 1000000 - -static void *hpet_ptr; - -static cycle_t read_hpet(void) -{ - return (cycle_t)readl(hpet_ptr); -} - -static cycle_t __vsyscall_fn vread_hpet(void) -{ - return readl((void __iomem *)fix_to_virt(VSYSCALL_HPET) + 0xf0); -} - -struct clocksource clocksource_hpet = { - .name = "hpet", - .rating = 250, - .read = read_hpet, - .mask = (cycle_t)HPET_MASK, - .mult = 0, /* set below */ - .shift = HPET_SHIFT, - .flags = CLOCK_SOURCE_IS_CONTINUOUS, - .vread = vread_hpet, -}; - -static int __init init_hpet_clocksource(void) -{ - unsigned long hpet_period; - void __iomem *hpet_base; - u64 tmp; - - if (!hpet_address) - return -ENODEV; - - /* calculate the hpet address: */ - hpet_base = ioremap_nocache(hpet_address, HPET_MMAP_SIZE); - hpet_ptr = hpet_base + HPET_COUNTER; - - /* calculate the frequency: */ - hpet_period = readl(hpet_base + HPET_PERIOD); - - /* - * 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); |