diff options
Diffstat (limited to 'arch/i386/kernel/timers/timer_hpet.c')
-rw-r--r-- | arch/i386/kernel/timers/timer_hpet.c | 217 |
1 files changed, 0 insertions, 217 deletions
diff --git a/arch/i386/kernel/timers/timer_hpet.c b/arch/i386/kernel/timers/timer_hpet.c deleted file mode 100644 index 17a6fe7..0000000 --- a/arch/i386/kernel/timers/timer_hpet.c +++ /dev/null @@ -1,217 +0,0 @@ -/* - * This code largely moved from arch/i386/kernel/time.c. - * See comments there for proper credits. - */ - -#include <linux/spinlock.h> -#include <linux/init.h> -#include <linux/timex.h> -#include <linux/errno.h> -#include <linux/string.h> -#include <linux/jiffies.h> - -#include <asm/timer.h> -#include <asm/io.h> -#include <asm/processor.h> - -#include "io_ports.h" -#include "mach_timer.h" -#include <asm/hpet.h> - -static unsigned long hpet_usec_quotient __read_mostly; /* convert hpet clks to usec */ -static unsigned long tsc_hpet_quotient __read_mostly; /* convert tsc to hpet clks */ -static unsigned long hpet_last; /* hpet counter value at last tick*/ -static unsigned long last_tsc_low; /* lsb 32 bits of Time Stamp Counter */ -static unsigned long last_tsc_high; /* msb 32 bits of Time Stamp Counter */ -static unsigned long long monotonic_base; -static seqlock_t monotonic_lock = SEQLOCK_UNLOCKED; - -/* convert from cycles(64bits) => nanoseconds (64bits) - * basic equation: - * ns = cycles / (freq / ns_per_sec) - * ns = cycles * (ns_per_sec / freq) - * ns = cycles * (10^9 / (cpu_khz * 10^3)) - * ns = cycles * (10^6 / cpu_khz) - * - * Then we use scaling math (suggested by george@mvista.com) to get: - * ns = cycles * (10^6 * SC / cpu_khz) / SC - * ns = cycles * cyc2ns_scale / SC - * - * And since SC is a constant power of two, we can convert the div - * into a shift. - * - * We can use khz divisor instead of mhz to keep a better percision, since - * cyc2ns_scale is limited to 10^6 * 2^10, which fits in 32 bits. - * (mathieu.desnoyers@polymtl.ca) - * - * -johnstul@us.ibm.com "math is hard, lets go shopping!" - */ -static unsigned long cyc2ns_scale __read_mostly; -#define CYC2NS_SCALE_FACTOR 10 /* 2^10, carefully chosen */ - -static inline void set_cyc2ns_scale(unsigned long cpu_khz) -{ - cyc2ns_scale = (1000000 << CYC2NS_SCALE_FACTOR)/cpu_khz; -} - -static inline unsigned long long cycles_2_ns(unsigned long long cyc) -{ - return (cyc * cyc2ns_scale) >> CYC2NS_SCALE_FACTOR; -} - -static unsigned long long monotonic_clock_hpet(void) -{ - unsigned long long last_offset, this_offset, base; - unsigned seq; - - /* atomically read monotonic base & last_offset */ - do { - seq = read_seqbegin(&monotonic_lock); - last_offset = ((unsigned long long)last_tsc_high<<32)|last_tsc_low; - base = monotonic_base; - } while (read_seqretry(&monotonic_lock, seq)); - - /* Read the Time Stamp Counter */ - rdtscll(this_offset); - - /* return the value in ns */ - return base + cycles_2_ns(this_offset - last_offset); -} - -static unsigned long get_offset_hpet(void) -{ - register unsigned long eax, edx; - - eax = hpet_readl(HPET_COUNTER); - eax -= hpet_last; /* hpet delta */ - eax = min(hpet_tick, eax); - /* - * Time offset = (hpet delta) * ( usecs per HPET clock ) - * = (hpet delta) * ( usecs per tick / HPET clocks per tick) - * = (hpet delta) * ( hpet_usec_quotient ) / (2^32) - * - * Where, - * hpet_usec_quotient = (2^32 * usecs per tick)/HPET clocks per tick - * - * Using a mull instead of a divl saves some cycles in critical path. - */ - ASM_MUL64_REG(eax, edx, hpet_usec_quotient, eax); - - /* our adjusted time offset in microseconds */ - return edx; -} - -static void mark_offset_hpet(void) -{ - unsigned long long this_offset, last_offset; - unsigned long offset; - - write_seqlock(&monotonic_lock); - last_offset = ((unsigned long long)last_tsc_high<<32)|last_tsc_low; - rdtsc(last_tsc_low, last_tsc_high); - - if (hpet_use_timer) - offset = hpet_readl(HPET_T0_CMP) - hpet_tick; - else - offset = hpet_readl(HPET_COUNTER); - if (unlikely(((offset - hpet_last) >= (2*hpet_tick)) && (hpet_last != 0))) { - int lost_ticks = ((offset - hpet_last) / hpet_tick) - 1; - jiffies_64 += lost_ticks; - } - hpet_last = offset; - - /* update the monotonic base value */ - this_offset = ((unsigned long long)last_tsc_high<<32)|last_tsc_low; - monotonic_base += cycles_2_ns(this_offset - last_offset); - write_sequnlock(&monotonic_lock); -} - -static void delay_hpet(unsigned long loops) -{ - unsigned long hpet_start, hpet_end; - unsigned long eax; - - /* loops is the number of cpu cycles. Convert it to hpet clocks */ - ASM_MUL64_REG(eax, loops, tsc_hpet_quotient, loops); - - hpet_start = hpet_readl(HPET_COUNTER); - do { - rep_nop(); - hpet_end = hpet_readl(HPET_COUNTER); - } while ((hpet_end - hpet_start) < (loops)); -} - -static struct timer_opts timer_hpet; - -static int __init init_hpet(char* override) -{ - unsigned long result, remain; - - /* check clock override */ - if (override[0] && strncmp(override,"hpet",4)) - return -ENODEV; - - if (!is_hpet_enabled()) - return -ENODEV; - - printk("Using HPET for gettimeofday\n"); - if (cpu_has_tsc) { - unsigned long tsc_quotient = calibrate_tsc_hpet(&tsc_hpet_quotient); - if (tsc_quotient) { - /* report CPU clock rate in Hz. - * The formula is (10^6 * 2^32) / (2^32 * 1 / (clocks/us)) = - * clock/second. Our precision is about 100 ppm. - */ - { unsigned long eax=0, edx=1000; - ASM_DIV64_REG(cpu_khz, edx, tsc_quotient, - eax, edx); - printk("Detected %u.%03u MHz processor.\n", - cpu_khz / 1000, cpu_khz % 1000); - } - set_cyc2ns_scale(cpu_khz); - } - /* set this only when cpu_has_tsc */ - timer_hpet.read_timer = read_timer_tsc; - } - - /* - * Math to calculate hpet to usec multiplier - * Look for the comments at get_offset_hpet() - */ - ASM_DIV64_REG(result, remain, hpet_tick, 0, KERNEL_TICK_USEC); - if (remain > (hpet_tick >> 1)) - result++; /* rounding the result */ - hpet_usec_quotient = result; - - return 0; -} - -static int hpet_resume(void) -{ - write_seqlock(&monotonic_lock); - /* Assume this is the last mark offset time */ - rdtsc(last_tsc_low, last_tsc_high); - - if (hpet_use_timer) - hpet_last = hpet_readl(HPET_T0_CMP) - hpet_tick; - else - hpet_last = hpet_readl(HPET_COUNTER); - write_sequnlock(&monotonic_lock); - return 0; -} -/************************************************************/ - -/* tsc timer_opts struct */ -static struct timer_opts timer_hpet __read_mostly = { - .name = "hpet", - .mark_offset = mark_offset_hpet, - .get_offset = get_offset_hpet, - .monotonic_clock = monotonic_clock_hpet, - .delay = delay_hpet, - .resume = hpet_resume, -}; - -struct init_timer_opts __initdata timer_hpet_init = { - .init = init_hpet, - .opts = &timer_hpet, -}; |