-
-#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);