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RIOT/cpu/x86/x86_hwtimer.c
René Kijewski 427a5fbaef core: let valid PIDs start with 1
2014-08-17 19:51:03 +02:00

546 lines
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/*
* Copyright (C) 2014 René Kijewski <rene.kijewski@fu-berlin.de>
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2.1 of the License, or (at your option) any later version.
*
* This library is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this library; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
*/
/**
* @ingroup x86-irq
* @{
*
* @file
* @brief Longterm and shortterm timeout handler using callbacks.
*
* @author René Kijewski <rene.kijewski@fu-berlin.de>
*
* @}
*/
#include "hwtimer_cpu.h"
#include "x86_hwtimer.h"
#include "x86_rtc.h"
#include "x86_threading.h"
#include "arch/hwtimer_arch.h"
#include "irq.h"
#include "thread.h"
#include <stdint.h>
#include <stdio.h>
#define ENABLE_DEBUG (0)
#include "debug.h"
#define US_PER_SECOND (1000l * 1000l)
#define START_MAX_US_PREMATURELY (US_PER_SECOND / 2048)
#define NNN_TS_ITERATIONS (1024)
#define NNN_TICK_ITERATIONS (16)
#define TICK_HZ_VAL (256)
#define TICK_HZ_REG_A (RTC_REG_A_HZ_256)
#define ASM_FUN_ATTRIBUTES \
__attribute__((noinline)) \
__attribute__((no_instrument_function)) \
__attribute__((optimize("Os", "omit-frame-pointer")))
static bool set_next_alarm(bool may_call);
static uint64_t ts_base;
static x86_rtc_data_t rtc_base;
static uint64_t ts_per_nop_nop_nop;
static uint64_t nop_nop_nops_per_tick;
static uint64_t nop_nop_nops_per_second;
static uint64_t instructions_per_second;
static void ASM_FUN_ATTRIBUTES nop_nop_nop(void)
{
# include "nop_nop_nop.inc"
}
static uint64_t ASM_FUN_ATTRIBUTES rdtsc(void)
{
uint64_t result;
asm volatile ("cpuid" :: "a"(0) : "ebx", "ecx", "edx");
asm volatile ("rdtsc" : "=A"(result));
return result;
}
static volatile bool periodic_interrupt_called;
static void flip_periodic_interrupt_called(uint8_t reg_c)
{
(void) reg_c;
periodic_interrupt_called = !periodic_interrupt_called;
}
static void measure_nop_nop_nops_per_tick(void)
{
x86_rtc_set_periodic_callback(flip_periodic_interrupt_called);
x86_rtc_set_periodic(TICK_HZ_REG_A, 0, KERNEL_PID_FIRST, true);
for (unsigned i = 0; i < NNN_TICK_ITERATIONS; ++i) {
periodic_interrupt_called = false;
eINT();
while (!periodic_interrupt_called) {
nop_nop_nop();
}
while (periodic_interrupt_called) {
nop_nop_nop();
}
uint64_t counting_start = rdtsc();
while (!periodic_interrupt_called) {
++nop_nop_nops_per_tick;
nop_nop_nop();
}
dINT();
uint64_t counting_end = rdtsc();
ts_per_nop_nop_nop += counting_end - counting_start;
}
x86_rtc_set_periodic_callback(NULL);
x86_rtc_set_periodic(RTC_REG_A_HZ_OFF, 0, KERNEL_PID_UNDEF, false);
/* instructions_per_second = nop_nop_nops_per_second * ts_per_nop_nop_nop: */
instructions_per_second = nop_nop_nops_per_tick * TICK_HZ_VAL * ts_per_nop_nop_nop / nop_nop_nops_per_tick / NNN_TICK_ITERATIONS;
/* nop_nop_nops_per_second = nop_nop_nops_per_tick / TICK_HZ_VAL: */
nop_nop_nops_per_second = (nop_nop_nops_per_tick * TICK_HZ_VAL) / NNN_TICK_ITERATIONS;
ts_per_nop_nop_nop /= nop_nop_nops_per_tick;
nop_nop_nops_per_tick /= NNN_TICK_ITERATIONS;
}
static void update_cb(uint8_t reg_c)
{
periodic_interrupt_called = reg_c & RTC_REG_C_IRQ_UPDATE;
DEBUG("DEBUG update_cb(0x%02hhx): periodic_interrupt_called = %u\n", reg_c, periodic_interrupt_called);
}
static void init_bases(void)
{
x86_rtc_set_periodic_callback(update_cb);
x86_rtc_set_periodic(RTC_REG_A_HZ_2, 0, KERNEL_PID_FIRST, true);
eINT();
periodic_interrupt_called = false;
while (!periodic_interrupt_called) {
asm volatile ("hlt");
}
dINT();
x86_rtc_read(&rtc_base);
ts_base = rdtsc();
printf(" %02hhu:%02hhu:%02hhu, %04u-%02hhu-%02hhu is %llu\n",
rtc_base.hour, rtc_base.minute, rtc_base.second,
rtc_base.century * 100 + rtc_base.year, rtc_base.month, rtc_base.day,
ts_base);
x86_rtc_set_periodic_callback(NULL);
x86_rtc_set_periodic(RTC_REG_A_HZ_OFF, 0, KERNEL_PID_UNDEF, false);
}
void x86_init_hwtimer(void)
{
puts("Measuring CPU speed:");
measure_nop_nop_nops_per_tick();
printf(" CPU speed = %.3f MHz\n", instructions_per_second / (1024.f * 1024));
init_bases();
}
static void (*hwtimer_callback)(int timer);
static char hwtimer_stack[KERNEL_CONF_STACKSIZE_DEFAULT];
static kernel_pid_t hwtimer_pid = KERNEL_PID_UNDEF;
struct alarm_time {
uint64_t ts_absolute_alarm;
bool enabled;
struct alarm_time *next, *prev;
};
static struct alarm_time timers[HWTIMER_MAXTIMERS];
static struct alarm_time *timers_start;
static bool hwtimer_ie;
static unsigned rtc_alarm_ie, rtc_update_ie, rtc_periodic_ie;
static bool timer_unlink(unsigned i)
{
bool do_yield = false;
bool was_start = timers_start == &timers[i];
DEBUG("DEBUG timer_unlink(%u): was_start=%u\n", i, was_start);
if (timers[i].next) {
timers[i].next->prev = timers[i].prev;
}
if (timers[i].prev) {
timers[i].prev->next = timers[i].next;
}
if (was_start) {
timers_start = timers[i].next;
}
timers[i].next = timers[i].prev = NULL;
if (was_start && timers[i].enabled) {
do_yield = set_next_alarm(false);
}
timers[i].enabled = false;
return do_yield;
}
static void *hwtimer_tick_handler(void *arg)
{
(void) arg;
msg_t msg_array[2];
msg_init_queue(msg_array, sizeof (msg_array) / sizeof (*msg_array));
while (1) {
msg_t m;
msg_receive(&m);
dINT();
set_next_alarm(true);
eINT();
}
return NULL;
}
static void stop_alarms(void)
{
DEBUG("DEBUG stop_alarms(): AIE=%u, UIE=%u, PIE=%u\n",
rtc_alarm_ie, rtc_update_ie, rtc_periodic_ie);
if (rtc_alarm_ie) {
rtc_alarm_ie = 0;
x86_rtc_set_alarm(NULL, 0, KERNEL_PID_UNDEF, false);
}
if (rtc_update_ie) {
rtc_update_ie = 0;
x86_rtc_set_update(0, KERNEL_PID_UNDEF, false);
}
if (rtc_periodic_ie) {
rtc_periodic_ie = 0;
x86_rtc_set_periodic(RTC_REG_A_HZ_OFF, 0, KERNEL_PID_UNDEF, false);
}
}
static bool set_next_alarm(bool may_call)
{
if (!hwtimer_ie) {
return false;
}
while (timers_start) {
uint64_t ts_now = rdtsc();
int64_t ts_future = (int64_t) timers_start->ts_absolute_alarm - (int64_t) ts_now;
/* prevent overflows */
int64_t us_future = ts_future;
us_future *= (int64_t) (US_PER_SECOND / 0x1000);
us_future /= (int64_t) (instructions_per_second / 0x1000);
unsigned timer_i = timers_start - timers;
DEBUG("DEBUG set_next_alarm(): timers_start=%u, us_future=%lli, ts_future=%lli\n",
timer_i, us_future, ts_future);
if (us_future <= START_MAX_US_PREMATURELY) {
DEBUG(" callback(%u) (%lli µs prematurely), may_call=%u\n",
timer_i, us_future, may_call);
if (!may_call) {
msg_t m;
msg_send_int(&m, hwtimer_pid);
return true;
}
else {
bool do_yield = timer_unlink(timer_i);
eINT();
hwtimer_callback(timer_i);
if (do_yield) {
thread_yield();
}
dINT();
continue;
}
}
us_future -= START_MAX_US_PREMATURELY / 2;
if (us_future > 5 * US_PER_SECOND) {
us_future -= US_PER_SECOND;
int8_t seconds = (us_future / US_PER_SECOND) % 60;
int8_t minutes = (us_future / US_PER_SECOND) / 60 % 60;
int8_t hours = (us_future / US_PER_SECOND) / 60 / 60 % 24;
DEBUG(" setting AIE %02hhu:%02hhu:%02hhu\n", hours, minutes, seconds);
x86_rtc_data_t rtc_now;
x86_rtc_read(&rtc_now);
rtc_now.second += seconds;
if (rtc_now.second >= 60) {
rtc_now.second -= 60;
++minutes;
}
rtc_now.minute += minutes;
if (rtc_now.minute >= 60) {
rtc_now.minute -= 60;
++hours;
}
rtc_now.hour += hours;
if (rtc_now.hour > 24) {
rtc_now.hour -= 24;
}
rtc_alarm_ie = false;
stop_alarms();
x86_rtc_set_alarm(&rtc_now, 0, hwtimer_pid, true);
rtc_alarm_ie = true;
}
else if (us_future > 1 * US_PER_SECOND) {
DEBUG(" setting UIE\n");
rtc_update_ie = false;
stop_alarms();
x86_rtc_set_update(0, hwtimer_pid, true);
rtc_update_ie = true;
}
else {
/* TODO: this has to work without an epic if-else construct */
unsigned hz;
if ((unsigned long) us_future >= 1 * US_PER_SECOND / 2) {
hz = RTC_REG_A_HZ_2;
}
else if ((unsigned long) us_future >= 1 * US_PER_SECOND / 4) {
hz = RTC_REG_A_HZ_4;
}
else if ((unsigned long) us_future >= 1 * US_PER_SECOND / 8) {
hz = RTC_REG_A_HZ_8;
}
else if ((unsigned long) us_future >= 1 * US_PER_SECOND / 16) {
hz = RTC_REG_A_HZ_16;
}
else if ((unsigned long) us_future >= 1 * US_PER_SECOND / 32) {
hz = RTC_REG_A_HZ_32;
}
else if ((unsigned long) us_future >= 1 * US_PER_SECOND / 64) {
hz = RTC_REG_A_HZ_64;
}
else if ((unsigned long) us_future >= 1 * US_PER_SECOND / 128) {
hz = RTC_REG_A_HZ_128;
}
else if ((unsigned long) us_future >= 1 * US_PER_SECOND / 256) {
hz = RTC_REG_A_HZ_256;
}
else if ((unsigned long) us_future >= 1 * US_PER_SECOND / 512) {
hz = RTC_REG_A_HZ_512;
}
else if ((unsigned long) us_future >= 1 * US_PER_SECOND / 1024) {
hz = RTC_REG_A_HZ_1024;
}
else if ((unsigned long) us_future >= 1 * US_PER_SECOND / 2048) {
hz = RTC_REG_A_HZ_2048;
}
else if ((unsigned long) us_future < 1 * US_PER_SECOND / 4096) {
hz = RTC_REG_A_HZ_8192;
}
else {
hz = RTC_REG_A_HZ_4096;
}
if (hz != rtc_periodic_ie) {
DEBUG(" setting PIE reg_c |= 0x%02x\n", hz);
rtc_periodic_ie = false;
stop_alarms();
x86_rtc_set_periodic(hz, 0, hwtimer_pid, true);
rtc_periodic_ie = hz;
}
}
return false;
}
stop_alarms();
return false;
}
void hwtimer_arch_init(void (*handler)(int), uint32_t fcpu)
{
(void) fcpu;
hwtimer_callback = handler;
hwtimer_pid = thread_create(hwtimer_stack,
sizeof (hwtimer_stack),
1,
CREATE_STACKTEST,
hwtimer_tick_handler,
NULL,
"x86-hwtimer");
hwtimer_ie = true;
}
/* µs since x86_init_hwtimer() */
unsigned long hwtimer_arch_now(void)
{
unsigned old_state = disableIRQ();
uint64_t result = rdtsc();
restoreIRQ(old_state);
return (result - ts_base) * US_PER_SECOND / instructions_per_second;
}
void hwtimer_arch_set(unsigned long offset_us, short timer)
{
unsigned old_state = disableIRQ();
hwtimer_arch_set_absolute(offset_us + hwtimer_arch_now(), timer);
restoreIRQ(old_state);
}
void hwtimer_arch_enable_interrupt(void)
{
bool do_yield = false;
unsigned old_state = disableIRQ();
if (!hwtimer_ie) {
hwtimer_ie = true;
do_yield = set_next_alarm(false);
}
restoreIRQ(old_state);
if (do_yield) {
thread_yield();
}
}
void hwtimer_arch_disable_interrupt(void)
{
unsigned old_state = disableIRQ();
if (hwtimer_ie) {
stop_alarms();
hwtimer_ie = false;
}
restoreIRQ(old_state);
}
void hwtimer_arch_set_absolute(unsigned long value_us_, short timer)
{
unsigned old_state = disableIRQ();
DEBUG("DEBUG hwtimer_arch_set_absolute(%lu, %hu)\n", value_us_, timer);
bool new_top = false;
if (timers[timer].enabled) {
DEBUG(" overwriting timers[%u]\n", timer);
timers[timer].enabled = false;
timer_unlink(timer);
if (timers_start == &timers[timer]) {
new_top = true;
}
}
uint64_t now_ts = rdtsc();
uint64_t now_us = ((now_ts - ts_base) * US_PER_SECOND) / instructions_per_second;
uint64_t future_us = value_us_;
if (value_us_ < now_us) {
future_us += 0x10000ull * 0x10000ull;
}
future_us -= now_us;
uint64_t future_ts = (future_us * instructions_per_second) / US_PER_SECOND;
DEBUG(" future_us=%llu, future_ts=%llu, now_ts=%llu\n", future_us, future_ts, now_ts);
timers[timer].ts_absolute_alarm = future_ts + now_ts;
timers[timer].enabled = true;
if (timers_start) {
struct alarm_time *prev = timers_start;
while (1) {
if (prev->ts_absolute_alarm < timers[timer].ts_absolute_alarm) {
if (prev->next) {
prev = prev->next;
}
else {
prev->next = &timers[timer];
timers[timer].prev = prev;
break;
}
}
else {
timers[timer].next = prev;
timers[timer].prev = prev->prev;
if (timers[timer].prev) {
timers[timer].prev->next = &timers[timer];
}
else {
timers_start = &timers[timer];
new_top = true;
}
prev->prev = &timers[timer];
break;
}
}
}
else {
timers_start = &timers[timer];
new_top = true;
}
bool do_yield = false;
if (new_top) {
do_yield = set_next_alarm(false);
}
restoreIRQ(old_state);
if (do_yield) {
thread_yield();
}
}
void hwtimer_arch_unset(short timer)
{
bool do_yield = false;
unsigned old_state = disableIRQ();
if (timers[timer].enabled) {
bool new_top = timers[timer].prev == NULL;
timers[timer].enabled = false;
timer_unlink(timer);
if (new_top) {
do_yield = set_next_alarm(false);
}
}
restoreIRQ(old_state);
if (do_yield) {
thread_yield();
}
}
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