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/*

 * Copyright (c) 2001-2004 Jakub Jermar

 * All rights reserved.

 *

 * Redistribution and use in source and binary forms, with or without

 * modification, are permitted provided that the following conditions

 * are met:

 *

 * - Redistributions of source code must retain the above copyright

 *   notice, this list of conditions and the following disclaimer.

 * - 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.

 * - The name of the author may not be used to endorse or promote products

 *   derived from this software without specific prior written permission.

 *

 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``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 AUTHOR 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.

 */

/** @addtogroup ia32	

 * @{

 */

/**

 * @file

 * @brief	i8254 chip driver.

 *

 * Low level time functions.

 */

#include <arch/types.h>

#include <time/clock.h>

#include <time/delay.h>

#include <arch/cycle.h>

#include <arch/interrupt.h>

#include <arch/drivers/i8259.h>

#include <arch/drivers/i8254.h>

#include <cpu.h>

#include <config.h>

#include <arch/pm.h>

#include <arch/asm.h>

#include <arch/cpuid.h>

#include <arch.h>

#include <time/delay.h>

#include <ddi/irq.h>

#include <ddi/device.h>

#define CLK_PORT1	0x40

#define CLK_PORT4	0x43

#define CLK_CONST	1193180

#define MAGIC_NUMBER	1194

static irq_t i8254_irq;

static irq_ownership_t i8254_claim(void)

{

	return IRQ_ACCEPT;

}

static void i8254_irq_handler(irq_t *irq, void *arg __attribute__((unused)), ...)

{

	/*

	 * This IRQ is responsible for kernel preemption.

	 * Nevertheless, we are now holding a spinlock which prevents

	 * preemption. For this particular IRQ, we don't need the

	 * lock. We just release it, call clock() and then reacquire it again.

	 */

	spinlock_unlock(&irq->lock);

	clock();

	spinlock_lock(&irq->lock);

}

void i8254_init(void)

{

	irq_initialize(&i8254_irq);

	i8254_irq.preack = true;

	i8254_irq.devno = device_assign_devno();

	i8254_irq.inr = IRQ_CLK;

	i8254_irq.claim = i8254_claim;

	i8254_irq.handler = i8254_irq_handler;

	irq_register(&i8254_irq);

	i8254_normal_operation();

}

void i8254_normal_operation(void)

{

	pio_write_8(CLK_PORT4, 0x36);

	pic_disable_irqs(1 << IRQ_CLK);

	pio_write_8(CLK_PORT1, (CLK_CONST / HZ) & 0xf);

	pio_write_8(CLK_PORT1, (CLK_CONST / HZ) >> 8);

	pic_enable_irqs(1 << IRQ_CLK);

}

#define LOOPS 150000

#define SHIFT 11

void i8254_calibrate_delay_loop(void)

{

	uint64_t clk1, clk2;

	uint32_t t1, t2, o1, o2;

	uint8_t not_ok;

	/*

	 * One-shot timer. Count-down from 0xffff at 1193180Hz

	 * MAGIC_NUMBER is the magic value for 1ms.

	 */

	pio_write_8(CLK_PORT4, 0x30);

	pio_write_8(CLK_PORT1, 0xff);

	pio_write_8(CLK_PORT1, 0xff);

	do {

		/* will read both status and count */

		pio_write_8(CLK_PORT4, 0xc2);

		not_ok = (uint8_t) ((pio_read_8(CLK_PORT1) >> 6) & 1);

		t1 = pio_read_8(CLK_PORT1);

		t1 |= pio_read_8(CLK_PORT1) << 8;

	} while (not_ok);

	asm_delay_loop(LOOPS);

	pio_write_8(CLK_PORT4, 0xd2);

	t2 = pio_read_8(CLK_PORT1);

	t2 |= pio_read_8(CLK_PORT1) << 8;

	/*

	 * We want to determine the overhead of the calibrating mechanism.

	 */

	pio_write_8(CLK_PORT4, 0xd2);

	o1 = pio_read_8(CLK_PORT1);

	o1 |= pio_read_8(CLK_PORT1) << 8;

	asm_fake_loop(LOOPS);

	pio_write_8(CLK_PORT4, 0xd2);

	o2 = pio_read_8(CLK_PORT1);

	o2 |= pio_read_8(CLK_PORT1) << 8;

	CPU->delay_loop_const =

	    ((MAGIC_NUMBER * LOOPS) / 1000) / ((t1 - t2) - (o1 - o2)) +

	    (((MAGIC_NUMBER * LOOPS) / 1000) % ((t1 - t2) - (o1 - o2)) ? 1 : 0);

	clk1 = get_cycle();

	delay(1 << SHIFT);

	clk2 = get_cycle();

	CPU->frequency_mhz = (clk2 - clk1) >> SHIFT;

	return;

}

/** @}

 */