kern
view src/intr.c @ 27:7795225808b3
moved enable_intr out of init_intr and after the kernel initialization is completed
| author | John Tsiombikas <nuclear@member.fsf.org> |
|---|---|
| date | Sat, 09 Apr 2011 07:22:27 +0300 |
| parents | eaec918de072 |
| children | a2c6110bd24b 06172322fb76 |
line source
1 #include <stdio.h>
2 #include "intr.h"
3 #include "desc.h"
4 #include "segm.h"
5 #include "asmops.h"
6 #include "panic.h"
8 /* IDT gate descriptor bits */
9 #define GATE_TASK (5 << 8)
10 #define GATE_INTR (6 << 8)
11 #define GATE_TRAP (7 << 8)
12 #define GATE_DEFAULT (1 << 11)
13 #define GATE_PRESENT (1 << 15)
15 /* offset used to remap IRQ numbers (+32) */
16 #define IRQ_OFFSET 32
17 /* conversion macros between IRQ and interrupt numbers */
18 #define IRQ_TO_INTR(x) ((x) + IRQ_OFFSET)
19 #define INTR_TO_IRQ(x) ((x) - IRQ_OFFSET)
20 /* checks whether a particular interrupt is an remapped IRQ */
21 #define IS_IRQ(n) ((n) >= IRQ_OFFSET && (n) < IRQ_OFFSET + 16)
23 /* PIC command and data ports */
24 #define PIC1_CMD 0x20
25 #define PIC1_DATA 0x21
26 #define PIC2_CMD 0xa0
27 #define PIC2_DATA 0xa1
29 /* PIC initialization command word 1 bits */
30 #define ICW1_ICW4_NEEDED (1 << 0)
31 #define ICW1_SINGLE (1 << 1)
32 #define ICW1_INTERVAL4 (1 << 2)
33 #define ICW1_LEVEL (1 << 3)
34 #define ICW1_INIT (1 << 4)
35 /* PIC initialization command word 4 bits */
36 #define ICW4_8086 (1 << 0)
37 #define ICW4_AUTO_EOI (1 << 1)
38 #define ICW4_BUF_SLAVE (1 << 3) /* 1000 */
39 #define ICW4_BUF_MASTER (3 << 2) /* 1100 */
40 #define ICW4_SPECIAL (1 << 4)
42 /* PIC operation command word 2 bits */
43 #define OCW2_EOI (1 << 5)
46 /* structure used to pass the interrupt stack frame from the
47 * entry points to the C dispatch function.
48 */
49 struct intr_frame {
50 /* registers pushed by pusha in intr_entry_* */
51 uint32_t edi, esi, ebp, esp;
52 uint32_t ebx, edx, ecx, eax;
53 /* interrupt number and error code pushed in intr_entry_* */
54 uint32_t inum, err;
55 /* pushed by CPU during interrupt entry */
56 uint32_t eip, cs, eflags;
57 };
60 static void init_pic(int offset);
61 static void gate_desc(desc_t *desc, uint16_t sel, uint32_t addr, int dpl, int type);
62 static void set_intr_entry(int num, void (*handler)(void));
63 static void end_of_irq(int irq);
65 /* defined in intr-asm.S */
66 void set_idt(uint32_t addr, uint16_t limit);
67 void intr_entry_default(void);
69 /* the IDT (interrupt descriptor table) */
70 static desc_t idt[256];
71 /* table of handler functions for all interrupts */
72 static intr_func_t intr_func[256];
75 void init_intr(void)
76 {
77 int i;
79 set_idt((uint32_t)idt, sizeof idt - 1);
81 /* initialize all entry points and interrupt handlers */
82 for(i=0; i<256; i++) {
83 set_intr_entry(i, intr_entry_default);
84 interrupt(i, 0);
85 }
87 /* by including interrupts.h here (without ASM being defined)
88 * the series of INTR_ENTRY_* macros will be expanded to a series
89 * of function prototypes for all interrupt entry points and the
90 * corresponding calls to set_intr_entry to set up the IDT slots
91 */
92 #include "interrupts.h"
94 /* initialize the programmable interrupt controller
95 * setting up the maping of IRQs [0, 15] to interrupts [32, 47]
96 */
97 init_pic(IRQ_OFFSET);
98 }
100 /* set an interrupt handler function for a particular interrupt */
101 void interrupt(int intr_num, intr_func_t func)
102 {
103 intr_func[intr_num] = func;
104 }
106 /* this function is called from all interrupt entry points
107 * it calls the appropriate interrupt handlers if available and handles
108 * sending an end-of-interrupt command to the PICs when finished.
109 */
110 void dispatch_intr(struct intr_frame frm)
111 {
112 if(intr_func[frm.inum]) {
113 intr_func[frm.inum](frm.inum, frm.err);
114 } else {
115 if(frm.inum < 32) {
116 panic("unhandled exception %d, error code: %d\n", frm.inum, frm.err);
117 }
118 printf("unhandled interrupt %d\n", frm.inum);
119 }
121 if(IS_IRQ(frm.inum)) {
122 end_of_irq(INTR_TO_IRQ(frm.inum));
123 }
124 }
126 static void init_pic(int offset)
127 {
128 /* send ICW1 saying we'll follow with ICW4 later on */
129 outb(ICW1_INIT | ICW1_ICW4_NEEDED, PIC1_CMD);
130 outb(ICW1_INIT | ICW1_ICW4_NEEDED, PIC2_CMD);
131 /* send ICW2 with IRQ remapping */
132 outb(offset, PIC1_DATA);
133 outb(offset + 8, PIC2_DATA);
134 /* send ICW3 to setup the master/slave relationship */
135 /* ... set bit3 = 3rd interrupt input has a slave */
136 outb(4, PIC1_DATA);
137 /* ... set slave ID to 2 */
138 outb(2, PIC2_DATA);
139 /* send ICW4 to set 8086 mode (no calls generated) */
140 outb(ICW4_8086, PIC1_DATA);
141 outb(ICW4_8086, PIC2_DATA);
142 /* done, just reset the data port to 0 */
143 outb(0, PIC1_DATA);
144 outb(0, PIC2_DATA);
145 }
147 static void gate_desc(desc_t *desc, uint16_t sel, uint32_t addr, int dpl, int type)
148 {
149 /* first 16bit part is the low 16bits of the entry address */
150 desc->d[0] = addr & 0xffff;
151 /* second 16bit part is the segment selector for the entry code */
152 desc->d[1] = sel;
153 /* third 16bit part has the privilege level, type, and present bit */
154 desc->d[2] = ((dpl & 3) << 13) | type | GATE_DEFAULT | GATE_PRESENT;
155 /* last 16bit part is the high 16bits of the entry address */
156 desc->d[3] = (addr & 0xffff0000) >> 16;
157 }
159 #define IS_TRAP(n) ((n) < 32)
160 static void set_intr_entry(int num, void (*handler)(void))
161 {
162 int type = IS_TRAP(num) ? GATE_TRAP : GATE_INTR;
163 gate_desc(idt + num, selector(SEGM_KCODE, 0), (uint32_t)handler, 0, type);
164 }
166 static void end_of_irq(int irq)
167 {
168 if(irq > 7) {
169 outb(OCW2_EOI, PIC2_CMD);
170 }
171 outb(OCW2_EOI, PIC1_CMD);
172 }