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/****************************************************************************
* arch/x86/src/qemu/qemu_timerisr.c
*
* Copyright (C) 2011 Gregory Nutt. All rights reserved.
* Author: Gregory Nutt <spudmonkey@racsa.co.cr>
*
* Based on Bran's kernel development tutorials. Rewritten for JamesM's
* kernel development tutorials.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
*
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in
* the documentation and/or other materials provided with the
* distribution.
* 3. Neither the name NuttX nor the names of its contributors may be
* used to endorse or promote products derived from this software
* without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
* FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
* COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
* BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
* OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
* AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
* ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
* POSSIBILITY OF SUCH DAMAGE.
*
****************************************************************************/
/****************************************************************************
* Included Files
****************************************************************************/
#include <nuttx/config.h>
#include <stdint.h>
#include <time.h>
#include <debug.h>
#include <nuttx/arch.h>
#include <arch/io.h>
#include <arch/board/board.h>
#include "clock_internal.h"
#include "up_internal.h"
#include "up_arch.h"
#include "chip.h"
#include "qemu_internal.h"
/****************************************************************************
* Pre-processor Definitions
****************************************************************************/
/* Programmable interval timer (PIT)
*
* Fpit = Fin / divisor
* divisor = Fin / divisor
*
* Where:
*
* Fpit = The desired interrupt frequency.
* Fin = PIT input frequency (PIT_CLOCK provided in board.h)
*
* The desired timer interrupt frequency is provided by the definition CLK_TCK
* (see include/time.h). CLK_TCK defines the desired number of system clock
* ticks per second. That value is a user configurable setting that defaults
* to 100 (100 ticks per second = 10 MS interval).
*/
#define PIT_DIVISOR ((uint32_t)PIT_CLOCK/(uint32_t)CLK_TCK)
#define PIT_MODE 0x43
#define PIT_CH0 0x40
/****************************************************************************
* Private Types
****************************************************************************/
/****************************************************************************
* Private Function Prototypes
****************************************************************************/
static void pit_outb(uint8_t val, uint16_t addr) __attribute__((noinline));
static int up_timerisr(int irq, uint32_t *regs);
/****************************************************************************
* Private Functions
****************************************************************************/
/****************************************************************************
* Name pit_outb
*
* Description:
* A slightly slower version of outb
*
****************************************************************************/
static void pit_outb(uint8_t val, uint16_t addr)
{
outb(val, addr);
}
/****************************************************************************
* Function: up_timerisr
*
* Description:
* The timer ISR will perform a variety of services for various portions
* of the systems.
*
****************************************************************************/
static int up_timerisr(int irq, uint32_t *regs)
{
/* Process timer interrupt */
sched_process_timer();
return 0;
}
/****************************************************************************
* Global Functions
****************************************************************************/
/****************************************************************************
* Function: up_timerinit
*
* Description:
* This function is called during start-up to initialize
* the timer interrupt.
*
****************************************************************************/
void up_timerinit(void)
{
/* uint32_t to avoid compile time overflow errors */
uint32_t divisor = PIT_DIVISOR;
DEBUGASSERT(divisor <= 0xffff);
/* Attach to the timer interrupt handler */
(void)irq_attach(IRQ0, (xcpt_t)up_timerisr);
/* Send the command byte */
pit_outb(0x36, PIT_MODE);
/* Set the PIT input frequency divisor */
pit_outb((uint8_t)(divisor & 0xff), PIT_CH0);
pit_outb((uint8_t)((divisor >> 8) & 0xff), PIT_CH0);
}
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