nuclear@11: #include <stdio.h>
nuclear@11: #include "intr.h"
nuclear@11: #include "desc.h"
nuclear@11: #include "segm.h"
nuclear@11: #include "asmops.h"
nuclear@11: #include "panic.h"
nuclear@55: #include "syscall.h"
nuclear@11: 
nuclear@11: /* IDT gate descriptor bits */
nuclear@11: #define GATE_TASK		(5 << 8)
nuclear@11: #define GATE_INTR		(6 << 8)
nuclear@11: #define GATE_TRAP		(7 << 8)
nuclear@11: #define GATE_DEFAULT	(1 << 11)
nuclear@11: #define GATE_PRESENT	(1 << 15)
nuclear@11: 
nuclear@11: /* PIC command and data ports */
nuclear@11: #define PIC1_CMD	0x20
nuclear@11: #define PIC1_DATA	0x21
nuclear@11: #define PIC2_CMD	0xa0
nuclear@11: #define PIC2_DATA	0xa1
nuclear@11: 
nuclear@11: /* PIC initialization command word 1 bits */
nuclear@11: #define ICW1_ICW4_NEEDED	(1 << 0)
nuclear@11: #define ICW1_SINGLE			(1 << 1)
nuclear@11: #define ICW1_INTERVAL4		(1 << 2)
nuclear@11: #define ICW1_LEVEL			(1 << 3)
nuclear@11: #define ICW1_INIT			(1 << 4)
nuclear@11: /* PIC initialization command word 4 bits */
nuclear@11: #define ICW4_8086			(1 << 0)
nuclear@11: #define ICW4_AUTO_EOI		(1 << 1)
nuclear@11: #define ICW4_BUF_SLAVE		(1 << 3) /* 1000 */
nuclear@11: #define ICW4_BUF_MASTER		(3 << 2) /* 1100 */
nuclear@11: #define ICW4_SPECIAL		(1 << 4)
nuclear@11: 
nuclear@11: /* PIC operation command word 2 bits */
nuclear@11: #define OCW2_EOI	(1 << 5)
nuclear@11: 
nuclear@11: 
nuclear@11: static void init_pic(int offset);
nuclear@11: static void gate_desc(desc_t *desc, uint16_t sel, uint32_t addr, int dpl, int type);
nuclear@11: static void set_intr_entry(int num, void (*handler)(void));
nuclear@11: 
nuclear@11: /* defined in intr-asm.S */
nuclear@11: void set_idt(uint32_t addr, uint16_t limit);
nuclear@11: void intr_entry_default(void);
nuclear@11: 
nuclear@11: /* the IDT (interrupt descriptor table) */
nuclear@11: static desc_t idt[256];
nuclear@11: /* table of handler functions for all interrupts */
nuclear@11: static intr_func_t intr_func[256];
nuclear@11: 
nuclear@52: static struct intr_frame *cur_intr_frame;
nuclear@55: static int eoi_pending;
nuclear@52: 
nuclear@11: 
nuclear@11: void init_intr(void)
nuclear@11: {
nuclear@11: 	int i;
nuclear@11: 
nuclear@11: 	set_idt((uint32_t)idt, sizeof idt - 1);
nuclear@11: 
nuclear@11: 	/* initialize all entry points and interrupt handlers */
nuclear@11: 	for(i=0; i<256; i++) {
nuclear@11: 		set_intr_entry(i, intr_entry_default);
nuclear@11: 		interrupt(i, 0);
nuclear@11: 	}
nuclear@11: 
nuclear@11: 	/* by including interrupts.h here (without ASM being defined)
nuclear@11: 	 * the series of INTR_ENTRY_* macros will be expanded to a series
nuclear@11: 	 * of function prototypes for all interrupt entry points and the
nuclear@11: 	 * corresponding calls to set_intr_entry to set up the IDT slots
nuclear@11: 	 */
nuclear@11: #include "interrupts.h"
nuclear@11: 
nuclear@11: 	/* initialize the programmable interrupt controller
nuclear@11: 	 * setting up the maping of IRQs [0, 15] to interrupts [32, 47]
nuclear@11: 	 */
nuclear@11: 	init_pic(IRQ_OFFSET);
nuclear@55: 	eoi_pending = 0;
nuclear@11: }
nuclear@11: 
nuclear@52: /* retrieve the current interrupt frame.
nuclear@52:  * returns 0 when called during kernel init.
nuclear@52:  */
nuclear@52: struct intr_frame *get_intr_frame(void)
nuclear@52: {
nuclear@52: 	return cur_intr_frame;
nuclear@52: }
nuclear@52: 
nuclear@11: /* set an interrupt handler function for a particular interrupt */
nuclear@11: void interrupt(int intr_num, intr_func_t func)
nuclear@11: {
nuclear@11: 	intr_func[intr_num] = func;
nuclear@11: }
nuclear@11: 
nuclear@11: /* this function is called from all interrupt entry points
nuclear@11:  * it calls the appropriate interrupt handlers if available and handles
nuclear@11:  * sending an end-of-interrupt command to the PICs when finished.
nuclear@11:  */
nuclear@11: void dispatch_intr(struct intr_frame frm)
nuclear@11: {
nuclear@52: 	cur_intr_frame = &frm;
nuclear@52: 
nuclear@55: 	if(IS_IRQ(frm.inum)) {
nuclear@55: 		eoi_pending = frm.inum;
nuclear@55: 	}
nuclear@55: 
nuclear@11: 	if(intr_func[frm.inum]) {
nuclear@52: 		intr_func[frm.inum](frm.inum);
nuclear@11: 	} else {
nuclear@11: 		if(frm.inum < 32) {
nuclear@11: 			panic("unhandled exception %d, error code: %d\n", frm.inum, frm.err);
nuclear@11: 		}
nuclear@11: 		printf("unhandled interrupt %d\n", frm.inum);
nuclear@11: 	}
nuclear@11: 
nuclear@55: 	disable_intr();
nuclear@55: 	if(eoi_pending) {
nuclear@55: 		end_of_irq(INTR_TO_IRQ(eoi_pending));
nuclear@11: 	}
nuclear@11: }
nuclear@11: 
nuclear@11: static void init_pic(int offset)
nuclear@11: {
nuclear@11: 	/* send ICW1 saying we'll follow with ICW4 later on */
nuclear@11: 	outb(ICW1_INIT | ICW1_ICW4_NEEDED, PIC1_CMD);
nuclear@11: 	outb(ICW1_INIT | ICW1_ICW4_NEEDED, PIC2_CMD);
nuclear@11: 	/* send ICW2 with IRQ remapping */
nuclear@11: 	outb(offset, PIC1_DATA);
nuclear@11: 	outb(offset + 8, PIC2_DATA);
nuclear@11: 	/* send ICW3 to setup the master/slave relationship */
nuclear@11: 	/* ... set bit3 = 3rd interrupt input has a slave */
nuclear@11: 	outb(4, PIC1_DATA);
nuclear@11: 	/* ... set slave ID to 2 */
nuclear@11: 	outb(2, PIC2_DATA);
nuclear@11: 	/* send ICW4 to set 8086 mode (no calls generated) */
nuclear@11: 	outb(ICW4_8086, PIC1_DATA);
nuclear@11: 	outb(ICW4_8086, PIC2_DATA);
nuclear@11: 	/* done, just reset the data port to 0 */
nuclear@11: 	outb(0, PIC1_DATA);
nuclear@11: 	outb(0, PIC2_DATA);
nuclear@11: }
nuclear@11: 
nuclear@11: static void gate_desc(desc_t *desc, uint16_t sel, uint32_t addr, int dpl, int type)
nuclear@11: {
nuclear@11: 	/* first 16bit part is the low 16bits of the entry address */
nuclear@11: 	desc->d[0] = addr & 0xffff;
nuclear@11: 	/* second 16bit part is the segment selector for the entry code */
nuclear@11: 	desc->d[1] = sel;
nuclear@11: 	/* third 16bit part has the privilege level, type, and present bit */
nuclear@11: 	desc->d[2] = ((dpl & 3) << 13) | type | GATE_DEFAULT | GATE_PRESENT;
nuclear@11: 	/* last 16bit part is the high 16bits of the entry address */
nuclear@11: 	desc->d[3] = (addr & 0xffff0000) >> 16;
nuclear@11: }
nuclear@11: 
nuclear@29: #define IS_TRAP(n)	((n) >= 32 && !IS_IRQ(n))
nuclear@11: static void set_intr_entry(int num, void (*handler)(void))
nuclear@11: {
nuclear@11: 	int type = IS_TRAP(num) ? GATE_TRAP : GATE_INTR;
nuclear@55: 
nuclear@55: 	/* the syscall interrupt has to have a dpl of 3 otherwise calling it from
nuclear@55: 	 * user space will raise a general protection exception. All the rest should
nuclear@55: 	 * have a dpl of 0 to disallow user programs to execute critical interrupt
nuclear@55: 	 * handlers and possibly crashing the system.
nuclear@55: 	 */
nuclear@55: 	int dpl = (num == SYSCALL_INT) ? 3 : 0;
nuclear@55: 
nuclear@55: 	gate_desc(idt + num, selector(SEGM_KCODE, 0), (uint32_t)handler, dpl, type);
nuclear@11: }
nuclear@11: 
nuclear@51: void end_of_irq(int irq)
nuclear@11: {
nuclear@55: 	int intr_state = get_intr_state();
nuclear@55: 	disable_intr();
nuclear@55: 
nuclear@55: 	if(!eoi_pending) {
nuclear@55: 		return;
nuclear@55: 	}
nuclear@55: 	eoi_pending = 0;
nuclear@55: 
nuclear@11: 	if(irq > 7) {
nuclear@11: 		outb(OCW2_EOI, PIC2_CMD);
nuclear@11: 	}
nuclear@11: 	outb(OCW2_EOI, PIC1_CMD);
nuclear@55: 
nuclear@55: 	set_intr_state(intr_state);
nuclear@11: }