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/*
* QEMU OpenRISC timer support
*
* Copyright (c) 2011-2012 Jia Liu <proljc@gmail.com>
* Zhizhou Zhang <etouzh@gmail.com>
*
* 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 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, see <http://www.gnu.org/licenses/>.
*/
#include "qemu/osdep.h"
#include "cpu.h"
#include "hw/hw.h"
#include "qemu/timer.h"
#define TIMER_PERIOD 50 /* 50 ns period for 20 MHz timer */
/* The time when TTCR changes */
static uint64_t last_clk;
static int is_counting;
void cpu_openrisc_count_update(OpenRISCCPU *cpu)
{
uint64_t now;
if (!is_counting) {
return;
}
now = qemu_clock_get_ns(QEMU_CLOCK_VIRTUAL);
cpu->env.ttcr += (uint32_t)((now - last_clk) / TIMER_PERIOD);
last_clk = now;
}
void cpu_openrisc_timer_update(OpenRISCCPU *cpu)
{
uint32_t wait;
uint64_t now, next;
if (!is_counting) {
return;
}
cpu_openrisc_count_update(cpu);
now = last_clk;
if ((cpu->env.ttmr & TTMR_TP) <= (cpu->env.ttcr & TTMR_TP)) {
wait = TTMR_TP - (cpu->env.ttcr & TTMR_TP) + 1;
wait += cpu->env.ttmr & TTMR_TP;
} else {
wait = (cpu->env.ttmr & TTMR_TP) - (cpu->env.ttcr & TTMR_TP);
}
next = now + (uint64_t)wait * TIMER_PERIOD;
timer_mod(cpu->env.timer, next);
}
void cpu_openrisc_count_start(OpenRISCCPU *cpu)
{
is_counting = 1;
cpu_openrisc_count_update(cpu);
}
void cpu_openrisc_count_stop(OpenRISCCPU *cpu)
{
timer_del(cpu->env.timer);
cpu_openrisc_count_update(cpu);
is_counting = 0;
}
static void openrisc_timer_cb(void *opaque)
{
OpenRISCCPU *cpu = opaque;
if ((cpu->env.ttmr & TTMR_IE) &&
timer_expired(cpu->env.timer, qemu_clock_get_ns(QEMU_CLOCK_VIRTUAL))) {
CPUState *cs = CPU(cpu);
cpu->env.ttmr |= TTMR_IP;
cs->interrupt_request |= CPU_INTERRUPT_TIMER;
}
switch (cpu->env.ttmr & TTMR_M) {
case TIMER_NONE:
break;
case TIMER_INTR:
cpu->env.ttcr = 0;
break;
case TIMER_SHOT:
cpu_openrisc_count_stop(cpu);
break;
case TIMER_CONT:
break;
}
cpu_openrisc_timer_update(cpu);
}
void cpu_openrisc_clock_init(OpenRISCCPU *cpu)
{
cpu->env.timer = timer_new_ns(QEMU_CLOCK_VIRTUAL, &openrisc_timer_cb, cpu);
cpu->env.ttmr = 0x00000000;
cpu->env.ttcr = 0x00000000;
}
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