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/*-*- mode:c;indent-tabs-mode:nil;c-basic-offset:2;tab-width:8;coding:utf-8 -*-│
│vi: set net ft=c ts=2 sts=2 sw=2 fenc=utf-8 :vi│
╞══════════════════════════════════════════════════════════════════════════════╡
│ Copyright 2020 Justine Alexandra Roberts Tunney │
│ │
│ This program is free software; you can redistribute it and/or modify │
│ it under the terms of the GNU General Public License as published by │
│ the Free Software Foundation; version 2 of the License. │
│ │
│ This program is distributed in the hope that it will be useful, but │
│ WITHOUT ANY WARRANTY; without even the implied warranty of │
│ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU │
│ General Public License for more details. │
│ │
│ You should have received a copy of the GNU General Public License │
│ along with this program; if not, write to the Free Software │
│ Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA │
│ 02110-1301 USA │
╚─────────────────────────────────────────────────────────────────────────────*/
#include "ape/lib/pc.h"
#define ICW1_ICW4 0x01 /* ICW4 (not) needed */
#define ICW1_SINGLE 0x02 /* Single (cascade) mode */
#define ICW1_INTERVAL4 0x04 /* Call address interval 4 (8) */
#define ICW1_LEVEL 0x08 /* Level triggered (edge) mode */
#define ICW1_INIT 0x10 /* Initialization - required! */
#define ICW4_8086 0x01 /* 8086/88 (MCS-80/85) mode */
#define ICW4_AUTO 0x02 /* Auto (normal) EOI */
#define ICW4_BUF_SLAVE 0x08 /* Buffered mode/slave */
#define ICW4_BUF_MASTER 0x0C /* Buffered mode/master */
#define ICW4_SFNM 0x10 /* Special fully nested (not) */
static inline void io_wait(void) {
/* Magic technique from Linux, according to:
* wiki.osdev.org/index.php?title=Inline_Assembly/Examples&oldid=23541
*/
outb(0x80, 0);
}
void PIC_sendEOI(unsigned char irq) {
if (irq >= 8) outb(PIC2_CMD, PIC_EOI);
outb(PIC1_CMD, PIC_EOI);
}
bool AreInterruptsEnabled() {
return (eflags() & kInterruptFlag) == kInterruptFlag;
}
nodiscard forceinline unsigned long irqdisable(void) {
unsigned long eflags;
asm("pushf\n\t"
"cli\n\t"
"pop\t%0"
: "=r"(eflags)
: /* no inputs */
: "cc");
return eflags;
}
forceinline void irqrestore(unsigned long eflags) {
asm volatile(
"push\t%0\n\t"
"popf"
: /* no outputs */
: "rm"(eflags)
: "cc");
}
/**
* @param offset1 is vector offset for master PIC
* vectors on the master become offset1..offset1+7
* @param offset2 is same for slave PIC: offset2..offset2+7
**/
void PIC_remap(int offset1, int offset2) {
unsigned char a1, a2;
a1 = inb(PIC1_DATA); // save masks
a2 = inb(PIC2_DATA);
outb(PIC1_CMD,
ICW1_INIT |
ICW1_ICW4); // starts the initialization sequence (in cascade mode)
io_wait();
outb(PIC2_CMD, ICW1_INIT | ICW1_ICW4);
io_wait();
outb(PIC1_DATA, offset1); // ICW2: Master PIC vector offset
io_wait();
outb(PIC2_DATA, offset2); // ICW2: Slave PIC vector offset
io_wait();
outb(PIC1_DATA, 4); // ICW3: tell Master PIC that there is a slave PIC at
// IRQ2 (0000 0100)
io_wait();
outb(PIC2_DATA, 2); // ICW3: tell Slave PIC its cascade identity (0000 0010)
io_wait();
outb(PIC1_DATA, ICW4_8086);
io_wait();
outb(PIC2_DATA, ICW4_8086);
io_wait();
outb(PIC1_DATA, a1); // restore saved masks.
outb(PIC2_DATA, a2);
}
void IRQ_set_mask(unsigned char IRQline) {
uint16_t port;
uint8_t value;
if (IRQline < 8) {
port = PIC1_DATA;
} else {
port = PIC2_DATA;
IRQline -= 8;
}
value = inb(port) | (1 << IRQline);
outb(port, value);
}
void IRQ_clear_mask(unsigned char IRQline) {
uint16_t port;
uint8_t value;
if (IRQline < 8) {
port = PIC1_DATA;
} else {
port = PIC2_DATA;
IRQline -= 8;
}
value = inb(port) & ~(1 << IRQline);
outb(port, value);
}
static uint16_t __pic_get_irq_reg(int ocw3) {
/* OCW3 to PIC CMD to get the register values. PIC2 is chained, and
* represents IRQs 8-15. PIC1 is IRQs 0-7, with 2 being the chain */
outb(PIC1_CMD, ocw3);
outb(PIC2_CMD, ocw3);
return (inb(PIC2_CMD) << 8) | inb(PIC1_CMD);
}
/* Returns the combined value of the cascaded PICs irq request register */
uint16_t pic_get_irr(void) { return __pic_get_irq_reg(PIC_READ_IRR); }
/* Returns the combined value of the cascaded PICs in-service register */
uint16_t pic_get_isr(void) { return __pic_get_irq_reg(PIC_READ_ISR); }