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- /* A couple of routines to implement a low-overhead timer for drivers */
-
- /*
- * This program is free software; you can redistribute it and/or
- * modify it under the terms of the GNU General Public License as
- * published by the Free Software Foundation; either version 2, or (at
- * your option) any later version.
- */
-
- #include "timer.h"
- #include "latch.h"
- #include <io.h>
- #include <gpxe/init.h>
-
- void __load_timer2(unsigned int ticks)
- {
- /*
- * Now let's take care of PPC channel 2
- *
- * Set the Gate high, program PPC channel 2 for mode 0,
- * (interrupt on terminal count mode), binary count,
- * load 5 * LATCH count, (LSB and MSB) to begin countdown.
- *
- * Note some implementations have a bug where the high bits byte
- * of channel 2 is ignored.
- */
- /* Set up the timer gate, turn off the speaker */
- /* Set the Gate high, disable speaker */
- outb((inb(PPC_PORTB) & ~PPCB_SPKR) | PPCB_T2GATE, PPC_PORTB);
- /* binary, mode 0, LSB/MSB, Ch 2 */
- outb(TIMER2_SEL|WORD_ACCESS|MODE0|BINARY_COUNT, TIMER_MODE_PORT);
- /* LSB of ticks */
- outb(ticks & 0xFF, TIMER2_PORT);
- /* MSB of ticks */
- outb(ticks >> 8, TIMER2_PORT);
- }
-
- static int __timer2_running(void)
- {
- return ((inb(PPC_PORTB) & PPCB_T2OUT) == 0);
- }
-
- #if !defined(CONFIG_TSC_CURRTICKS)
- static void setup_timers(void)
- {
- return;
- }
-
- void load_timer2(unsigned int ticks)
- {
- return __load_timer2(ticks);
- }
-
- int timer2_running(void)
- {
- return __timer2_running();
- }
-
- void ndelay(unsigned int nsecs)
- {
- waiton_timer2((nsecs * CLOCK_TICK_RATE)/1000000000);
- }
- void udelay(unsigned int usecs)
- {
- waiton_timer2((usecs * TICKS_PER_MS)/1000);
- }
- #endif /* !defined(CONFIG_TSC_CURRTICKS) */
-
- #if defined(CONFIG_TSC_CURRTICKS)
-
- #define rdtsc(low,high) \
- __asm__ __volatile__("rdtsc" : "=a" (low), "=d" (high))
-
- #define rdtscll(val) \
- __asm__ __volatile__ ("rdtsc" : "=A" (val))
-
-
- /* Number of clock ticks to time with the rtc */
- #define LATCH 0xFF
-
- #define LATCHES_PER_SEC ((CLOCK_TICK_RATE + (LATCH/2))/LATCH)
- #define TICKS_PER_LATCH ((LATCHES_PER_SEC + (TICKS_PER_SEC/2))/TICKS_PER_SEC)
-
- static void sleep_latch(void)
- {
- __load_timer2(LATCH);
- while(__timer2_running());
- }
-
- /* ------ Calibrate the TSC -------
- * Time how long it takes to excute a loop that runs in known time.
- * And find the convertion needed to get to CLOCK_TICK_RATE
- */
-
-
- static unsigned long long calibrate_tsc(void)
- {
- unsigned long startlow, starthigh;
- unsigned long endlow, endhigh;
-
- rdtsc(startlow,starthigh);
- sleep_latch();
- rdtsc(endlow,endhigh);
-
- /* 64-bit subtract - gcc just messes up with long longs */
- __asm__("subl %2,%0\n\t"
- "sbbl %3,%1"
- :"=a" (endlow), "=d" (endhigh)
- :"g" (startlow), "g" (starthigh),
- "0" (endlow), "1" (endhigh));
-
- /* Error: ECPUTOOFAST */
- if (endhigh)
- goto bad_ctc;
-
- endlow *= TICKS_PER_LATCH;
- return endlow;
-
- /*
- * 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:
- printf("bad_ctc\n");
- return 0;
- }
-
- static unsigned long clocks_per_tick;
- static void setup_timers(void)
- {
- if (!clocks_per_tick) {
- clocks_per_tick = calibrate_tsc();
- /* Display the CPU Mhz to easily test if the calibration was bad */
- printf("CPU %ld Mhz\n", (clocks_per_tick/1000 * TICKS_PER_SEC)/1000);
- }
- }
-
- unsigned long currticks(void)
- {
- unsigned long clocks_high, clocks_low;
- unsigned long currticks;
- /* Read the Time Stamp Counter */
- rdtsc(clocks_low, clocks_high);
-
- /* currticks = clocks / clocks_per_tick; */
- __asm__("divl %1"
- :"=a" (currticks)
- :"r" (clocks_per_tick), "0" (clocks_low), "d" (clocks_high));
-
-
- return currticks;
- }
-
- static unsigned long long timer_timeout;
- static int __timer_running(void)
- {
- unsigned long long now;
- rdtscll(now);
- return now < timer_timeout;
- }
-
- void udelay(unsigned int usecs)
- {
- unsigned long long now;
- rdtscll(now);
- timer_timeout = now + usecs * ((clocks_per_tick * TICKS_PER_SEC)/(1000*1000));
- while(__timer_running());
- }
- void ndelay(unsigned int nsecs)
- {
- unsigned long long now;
- rdtscll(now);
- timer_timeout = now + nsecs * ((clocks_per_tick * TICKS_PER_SEC)/(1000*1000*1000));
- while(__timer_running());
- }
-
- void load_timer2(unsigned int timer2_ticks)
- {
- unsigned long long now;
- unsigned long clocks;
- rdtscll(now);
- clocks = timer2_ticks * ((clocks_per_tick * TICKS_PER_SEC)/CLOCK_TICK_RATE);
- timer_timeout = now + clocks;
- }
-
- int timer2_running(void)
- {
- return __timer_running();
- }
-
- #endif /* RTC_CURRTICKS */
-
- struct init_fn timer_init_fn __init_fn ( INIT_NORMAL ) = {
- .initialise = setup_timers,
- };
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