2b793e4945
Make the frclock functions similar to the tsc utility functions. This way, we can call frclock functions from the framebuffer driver which will use frclock on ARM and tsc on X86. Also, frclock_64_to_micros computed seconds, not microseconds Change-Id: I6718ae0fb7db050794f6f032205923e1a32dc1ac
92 lines
2.3 KiB
C
92 lines
2.3 KiB
C
/* Some utility functions around the free running clock on ARM. The clock is
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* 32-bits wide, but we provide 64-bit wrapper functions to make it look
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* similar to the read_tsc functions. On hardware we could actually make use
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* of the timer overflow counter, but emulator doesn't emulate it. */
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#include "omap_timer_registers.h"
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#include <minix/minlib.h>
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#include <minix/sysutil.h>
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#include <minix/type.h>
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#include <sys/errno.h>
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#include <sys/types.h>
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#include <assert.h>
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static u64_t calib_hz = 1625000, Hz;
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#define MICROHZ 1000000ULL /* number of micros per second */
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#define MICROSPERTICK(h) (MICROHZ/(h)) /* number of micros per HZ tick */
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int
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micro_delay(u32_t micros)
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{
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u64_t start, delta, delta_end;
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Hz = sys_hz();
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/* Start of delay. */
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read_frclock_64(&start);
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delta_end = (calib_hz * micros) / MICROHZ;
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/* If we have to wait for at least one HZ tick, use the regular
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* tickdelay first. Round downwards on purpose, so the average
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* half-tick we wait short (depending on where in the current tick
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* we call tickdelay). We can correct for both overhead of tickdelay
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* itself and the short wait in the busywait later.
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*/
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if (micros >= MICROSPERTICK(Hz))
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tickdelay(micros*Hz/MICROHZ);
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/* Wait (the rest) of the delay time using busywait. */
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do {
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read_frclock_64(&delta);
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} while (delta_frclock_64(start, delta) < delta_end);
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return 0;
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}
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u32_t frclock_64_to_micros(u64_t tsc)
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{
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return (u32_t) tsc / (calib_hz / MICROHZ);
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}
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void
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read_frclock(u32_t *frclk)
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{
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extern struct minix_kerninfo *_minix_kerninfo;
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volatile u32_t *frclock;
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assert(frclk);
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frclock = (u32_t *)((u8_t *) _minix_kerninfo->minix_frclock+OMAP3_TCRR);
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*frclk = *frclock;
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}
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u32_t
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delta_frclock(u32_t base, u32_t cur)
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{
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u32_t delta;
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if (cur < base) {
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/* We have wrapped around, so delta is base to wrapping point
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* plus starting point (0) to cur. This supports wrapping once
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* only. */
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delta = (UINT_MAX - base) + cur;
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} else {
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delta = cur - base;
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}
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return delta;
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}
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void
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read_frclock_64(u64_t *frclk)
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{
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read_frclock((u32_t *) frclk);
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}
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u64_t
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delta_frclock_64(u64_t base, u64_t cur)
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{
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return (u64_t) delta_frclock((u32_t) base, (u32_t) cur);
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}
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