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/*
* (C) Copyright 2009
* Graeme Russ, <graeme.russ@gmail.com>
*
* (C) Copyright 2002
* Daniel Engström, Omicron Ceti AB, <daniel@omicron.se>
*
* SPDX-License-Identifier: GPL-2.0+
*/
/*
* This file provides the interrupt handling functionality for systems
* based on the standard PC/AT architecture using two cascaded i8259
* Programmable Interrupt Controllers.
*/
#include <common.h>
#include <asm/io.h>
#include <asm/i8259.h>
#include <asm/ibmpc.h>
#include <asm/interrupt.h>
#if CONFIG_SYS_NUM_IRQS != 16
#error "CONFIG_SYS_NUM_IRQS must equal 16 if CONFIG_SYS_NUM_IRQS is defined"
#endif
int i8259_init(void)
{
u8 i;
/* Mask all interrupts */
outb(0xff, MASTER_PIC + IMR);
outb(0xff, SLAVE_PIC + IMR);
/* Master PIC */
/* Place master PIC interrupts at INT20 */
/* ICW3, One slave PIC is present */
outb(ICW1_SEL|ICW1_EICW4, MASTER_PIC + ICW1);
outb(0x20, MASTER_PIC + ICW2);
outb(IR2, MASTER_PIC + ICW3);
outb(ICW4_PM, MASTER_PIC + ICW4);
for (i = 0; i < 8; i++)
outb(OCW2_SEOI | i, MASTER_PIC + OCW2);
/* Slave PIC */
/* Place slave PIC interrupts at INT28 */
/* Slave ID */
outb(ICW1_SEL|ICW1_EICW4, SLAVE_PIC + ICW1);
outb(0x28, SLAVE_PIC + ICW2);
outb(0x02, SLAVE_PIC + ICW3);
outb(ICW4_PM, SLAVE_PIC + ICW4);
for (i = 0; i < 8; i++)
outb(OCW2_SEOI | i, SLAVE_PIC + OCW2);
/*
* Enable cascaded interrupts by unmasking the cascade IRQ pin of
* the master PIC
*/
unmask_irq(2);
/* Interrupt 9 should be level triggered (SCI). The OS might do this */
configure_irq_trigger(9, true);
return 0;
}
void mask_irq(int irq)
{
int imr_port;
if (irq >= CONFIG_SYS_NUM_IRQS)
return;
if (irq > 7)
imr_port = SLAVE_PIC + IMR;
else
imr_port = MASTER_PIC + IMR;
outb(inb(imr_port) | (1 << (irq & 7)), imr_port);
}
void unmask_irq(int irq)
{
int imr_port;
if (irq >= CONFIG_SYS_NUM_IRQS)
return;
if (irq > 7)
imr_port = SLAVE_PIC + IMR;
else
imr_port = MASTER_PIC + IMR;
outb(inb(imr_port) & ~(1 << (irq & 7)), imr_port);
}
void specific_eoi(int irq)
{
if (irq >= CONFIG_SYS_NUM_IRQS)
return;
if (irq > 7) {
/*
* IRQ is on the slave - Issue a corresponding EOI to the
* slave PIC and an EOI for IRQ2 (the cascade interrupt)
* on the master PIC
*/
outb(OCW2_SEOI | (irq & 7), SLAVE_PIC + OCW2);
irq = SEOI_IR2;
}
outb(OCW2_SEOI | irq, MASTER_PIC + OCW2);
}
#define ELCR1 0x4d0
#define ELCR2 0x4d1
void configure_irq_trigger(int int_num, bool is_level_triggered)
{
u16 int_bits = inb(ELCR1) | (((u16)inb(ELCR2)) << 8);
debug("%s: current interrupts are 0x%x\n", __func__, int_bits);
if (is_level_triggered)
int_bits |= (1 << int_num);
else
int_bits &= ~(1 << int_num);
/* Write new values */
debug("%s: try to set interrupts 0x%x\n", __func__, int_bits);
outb((u8)(int_bits & 0xff), ELCR1);
outb((u8)(int_bits >> 8), ELCR2);
#ifdef PARANOID_IRQ_TRIGGERS
/*
* Try reading back the new values. This seems like an error but is
* not
*/
if (inb(ELCR1) != (int_bits & 0xff)) {
printf("%s: lower order bits are wrong: want 0x%x, got 0x%x\n",
__func__, (int_bits & 0xff), inb(ELCR1));
}
if (inb(ELCR2) != (int_bits >> 8)) {
printf("%s: higher order bits are wrong: want 0x%x, got 0x%x\n",
__func__, (int_bits>>8), inb(ELCR2));
}
#endif
}
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