diff options
Diffstat (limited to 'src/cpu/x86')
| -rw-r--r-- | src/cpu/x86/tsc/delay_tsc.c | 78 |
1 files changed, 1 insertions, 77 deletions
diff --git a/src/cpu/x86/tsc/delay_tsc.c b/src/cpu/x86/tsc/delay_tsc.c index 0784822b30..afcd1d1f7d 100644 --- a/src/cpu/x86/tsc/delay_tsc.c +++ b/src/cpu/x86/tsc/delay_tsc.c @@ -12,90 +12,14 @@ */ #include <arch/early_variables.h> -#include <console/console.h> -#include <arch/io.h> #include <cpu/x86/tsc.h> +#include <pc80/i8254.h> #include <smp/spinlock.h> #include <delay.h> #include <thread.h> static unsigned long clocks_per_usec CAR_GLOBAL; -#define CLOCK_TICK_RATE 1193180U /* Underlying HZ */ - -/* ------ Calibrate the TSC ------- - * Too much 64-bit arithmetic here to do this cleanly in C, and for - * accuracy's sake we want to keep the overhead on the CTC speaker (channel 2) - * output busy loop as low as possible. We avoid reading the CTC registers - * directly because of the awkward 8-bit access mechanism of the 82C54 - * device. - */ - -#define CALIBRATE_INTERVAL ((2*CLOCK_TICK_RATE)/1000) /* 2ms */ -#define CALIBRATE_DIVISOR (2*1000) /* 2ms / 2000 == 1usec */ - -static unsigned long calibrate_tsc_with_pit(void) -{ - /* Set the Gate high, disable speaker */ - outb((inb(0x61) & ~0x02) | 0x01, 0x61); - - /* - * Now let's take care of CTC channel 2 - * - * Set the Gate high, program CTC channel 2 for mode 0, - * (interrupt on terminal count mode), binary count, - * load 5 * LATCH count, (LSB and MSB) to begin countdown. - */ - outb(0xb0, 0x43); /* binary, mode 0, LSB/MSB, Ch 2 */ - - outb(CALIBRATE_INTERVAL & 0xff, 0x42); /* LSB of count */ - outb(CALIBRATE_INTERVAL >> 8, 0x42); /* MSB of count */ - - { - tsc_t start; - tsc_t end; - unsigned long count; - - start = rdtsc(); - count = 0; - do { - count++; - } while ((inb(0x61) & 0x20) == 0); - end = rdtsc(); - - /* Error: ECTCNEVERSET */ - if (count <= 1) - goto bad_ctc; - - /* 64-bit subtract - gcc just messes up with long longs */ - __asm__("subl %2,%0\n\t" - "sbbl %3,%1" - : "=a" (end.lo), "=d" (end.hi) - : "g" (start.lo), "g" (start.hi), - "0" (end.lo), "1" (end.hi)); - - /* Error: ECPUTOOFAST */ - if (end.hi) - goto bad_ctc; - - - /* Error: ECPUTOOSLOW */ - if (end.lo <= CALIBRATE_DIVISOR) - goto bad_ctc; - - return DIV_ROUND_UP(end.lo, CALIBRATE_DIVISOR); - } - - /* - * The CTC wasn't reliable: we got a hit on the very first read, - * or the CPU was so fast/slow that the quotient wouldn't fit in - * 32 bits.. - */ -bad_ctc: - printk(BIOS_ERR, "bad_ctc\n"); - return 0; -} - static unsigned long calibrate_tsc(void) { if (CONFIG(TSC_CONSTANT_RATE)) |