3 * Graeme Russ, <graeme.russ@gmail.com>
6 * Daniel Engström, Omicron Ceti AB, <daniel@omicron.se>
8 * SPDX-License-Identifier: GPL-2.0+
12 * This file provides the interrupt handling functionality for systems
13 * based on the standard PC/AT architecture using two cascaded i8259
14 * Programmable Interrupt Controllers.
19 #include <asm/i8259.h>
20 #include <asm/ibmpc.h>
21 #include <asm/interrupt.h>
27 /* Mask all interrupts */
28 outb(0xff, MASTER_PIC + IMR);
29 outb(0xff, SLAVE_PIC + IMR);
33 * Place master PIC interrupts at INT20
35 outb(ICW1_SEL | ICW1_EICW4, MASTER_PIC + ICW1);
36 outb(0x20, MASTER_PIC + ICW2);
37 outb(IR2, MASTER_PIC + ICW3);
38 outb(ICW4_PM, MASTER_PIC + ICW4);
40 for (i = 0; i < 8; i++)
41 outb(OCW2_SEOI | i, MASTER_PIC + OCW2);
45 * Place slave PIC interrupts at INT28
47 outb(ICW1_SEL | ICW1_EICW4, SLAVE_PIC + ICW1);
48 outb(0x28, SLAVE_PIC + ICW2);
49 outb(0x02, SLAVE_PIC + ICW3);
50 outb(ICW4_PM, SLAVE_PIC + ICW4);
52 for (i = 0; i < 8; i++)
53 outb(OCW2_SEOI | i, SLAVE_PIC + OCW2);
56 * Enable cascaded interrupts by unmasking the cascade IRQ pin of
61 /* Interrupt 9 should be level triggered (SCI). The OS might do this */
62 configure_irq_trigger(9, true);
67 void mask_irq(int irq)
71 if (irq >= SYS_NUM_IRQS)
75 imr_port = SLAVE_PIC + IMR;
77 imr_port = MASTER_PIC + IMR;
79 outb(inb(imr_port) | (1 << (irq & 7)), imr_port);
82 void unmask_irq(int irq)
86 if (irq >= SYS_NUM_IRQS)
90 imr_port = SLAVE_PIC + IMR;
92 imr_port = MASTER_PIC + IMR;
94 outb(inb(imr_port) & ~(1 << (irq & 7)), imr_port);
97 void specific_eoi(int irq)
99 if (irq >= SYS_NUM_IRQS)
104 * IRQ is on the slave - Issue a corresponding EOI to the
105 * slave PIC and an EOI for IRQ2 (the cascade interrupt)
108 outb(OCW2_SEOI | (irq & 7), SLAVE_PIC + OCW2);
112 outb(OCW2_SEOI | irq, MASTER_PIC + OCW2);
115 void configure_irq_trigger(int int_num, bool is_level_triggered)
117 u16 int_bits = inb(ELCR1) | (((u16)inb(ELCR2)) << 8);
119 debug("%s: current interrupts are 0x%x\n", __func__, int_bits);
120 if (is_level_triggered)
121 int_bits |= (1 << int_num);
123 int_bits &= ~(1 << int_num);
125 /* Write new values */
126 debug("%s: try to set interrupts 0x%x\n", __func__, int_bits);
127 outb((u8)(int_bits & 0xff), ELCR1);
128 outb((u8)(int_bits >> 8), ELCR2);