/*
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* (C) Copyright 2009
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* Graeme Russ, <graeme.russ@gmail.com>
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*
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* (C) Copyright 2002
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* Daniel Engström, Omicron Ceti AB, <daniel@omicron.se>
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*
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* SPDX-License-Identifier: GPL-2.0+
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*/
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/*
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* This file provides the interrupt handling functionality for systems
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* based on the standard PC/AT architecture using two cascaded i8259
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* Programmable Interrupt Controllers.
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*/
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#include <common.h>
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#include <asm/io.h>
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#include <asm/i8259.h>
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#include <asm/ibmpc.h>
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#include <asm/interrupt.h>
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int i8259_init(void)
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{
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u8 i;
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/* Mask all interrupts */
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outb(0xff, MASTER_PIC + IMR);
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outb(0xff, SLAVE_PIC + IMR);
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/*
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* Master PIC
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* Place master PIC interrupts at INT20
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*/
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outb(ICW1_SEL | ICW1_EICW4, MASTER_PIC + ICW1);
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outb(0x20, MASTER_PIC + ICW2);
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outb(IR2, MASTER_PIC + ICW3);
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outb(ICW4_PM, MASTER_PIC + ICW4);
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for (i = 0; i < 8; i++)
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outb(OCW2_SEOI | i, MASTER_PIC + OCW2);
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/*
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* Slave PIC
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* Place slave PIC interrupts at INT28
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*/
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outb(ICW1_SEL | ICW1_EICW4, SLAVE_PIC + ICW1);
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outb(0x28, SLAVE_PIC + ICW2);
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outb(0x02, SLAVE_PIC + ICW3);
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outb(ICW4_PM, SLAVE_PIC + ICW4);
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for (i = 0; i < 8; i++)
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outb(OCW2_SEOI | i, SLAVE_PIC + OCW2);
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/*
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* Enable cascaded interrupts by unmasking the cascade IRQ pin of
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* the master PIC
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*/
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unmask_irq(2);
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/* Interrupt 9 should be level triggered (SCI). The OS might do this */
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configure_irq_trigger(9, true);
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return 0;
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}
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void mask_irq(int irq)
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{
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int imr_port;
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if (irq >= SYS_NUM_IRQS)
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return;
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if (irq > 7)
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imr_port = SLAVE_PIC + IMR;
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else
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imr_port = MASTER_PIC + IMR;
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outb(inb(imr_port) | (1 << (irq & 7)), imr_port);
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}
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void unmask_irq(int irq)
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{
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int imr_port;
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if (irq >= SYS_NUM_IRQS)
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return;
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if (irq > 7)
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imr_port = SLAVE_PIC + IMR;
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else
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imr_port = MASTER_PIC + IMR;
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outb(inb(imr_port) & ~(1 << (irq & 7)), imr_port);
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}
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void specific_eoi(int irq)
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{
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if (irq >= SYS_NUM_IRQS)
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return;
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if (irq > 7) {
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/*
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* IRQ is on the slave - Issue a corresponding EOI to the
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* slave PIC and an EOI for IRQ2 (the cascade interrupt)
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* on the master PIC
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*/
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outb(OCW2_SEOI | (irq & 7), SLAVE_PIC + OCW2);
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irq = SEOI_IR2;
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}
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outb(OCW2_SEOI | irq, MASTER_PIC + OCW2);
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}
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void configure_irq_trigger(int int_num, bool is_level_triggered)
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{
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u16 int_bits = inb(ELCR1) | (((u16)inb(ELCR2)) << 8);
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debug("%s: current interrupts are 0x%x\n", __func__, int_bits);
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if (is_level_triggered)
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int_bits |= (1 << int_num);
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else
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int_bits &= ~(1 << int_num);
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/* Write new values */
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debug("%s: try to set interrupts 0x%x\n", __func__, int_bits);
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outb((u8)(int_bits & 0xff), ELCR1);
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outb((u8)(int_bits >> 8), ELCR2);
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}
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