#include "mach_timer.h"
#include <asm/hpet.h>
-static unsigned long hpet_usec_quotient; /* convert hpet clks to usec */
-static unsigned long tsc_hpet_quotient; /* convert tsc to hpet clks */
+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 */
* basic equation:
* ns = cycles / (freq / ns_per_sec)
* ns = cycles * (ns_per_sec / freq)
- * ns = cycles * (10^9 / (cpu_mhz * 10^6))
- * ns = cycles * (10^3 / cpu_mhz)
+ * 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 * (10^3 * SC / cpu_mhz) / SC
+ * 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;
#define CYC2NS_SCALE_FACTOR 10 /* 2^10, carefully chosen */
-static inline void set_cyc2ns_scale(unsigned long cpu_mhz)
+static inline void set_cyc2ns_scale(unsigned long cpu_khz)
{
- cyc2ns_scale = (1000 << CYC2NS_SCALE_FACTOR)/cpu_mhz;
+ cyc2ns_scale = (1000000 << CYC2NS_SCALE_FACTOR)/cpu_khz;
}
static inline unsigned long long cycles_2_ns(unsigned long long cyc)
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)
last_offset = ((unsigned long long)last_tsc_high<<32)|last_tsc_low;
rdtsc(last_tsc_low, last_tsc_high);
- offset = hpet_readl(HPET_T0_CMP) - hpet_tick;
- if (unlikely(((offset - hpet_last) > hpet_tick) && (hpet_last != 0))) {
- int lost_ticks = (offset - hpet_last) / hpet_tick;
+ 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;
write_sequnlock(&monotonic_lock);
}
-void delay_hpet(unsigned long loops)
+static void delay_hpet(unsigned long loops)
{
unsigned long hpet_start, hpet_end;
unsigned long eax;
} while ((hpet_end - hpet_start) < (loops));
}
+static struct timer_opts timer_hpet;
+
static int __init init_hpet(char* override)
{
unsigned long result, remain;
{ unsigned long eax=0, edx=1000;
ASM_DIV64_REG(cpu_khz, edx, tsc_quotient,
eax, edx);
- printk("Detected %lu.%03lu MHz processor.\n",
+ printk("Detected %u.%03u MHz processor.\n",
cpu_khz / 1000, cpu_khz % 1000);
}
- set_cyc2ns_scale(cpu_khz/1000);
+ set_cyc2ns_scale(cpu_khz);
}
+ /* set this only when cpu_has_tsc */
+ timer_hpet.read_timer = read_timer_tsc;
}
/*
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 = {
+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 = {