From 0ad50c878838640ce53c202ab028d7b2c5810fe6 Mon Sep 17 00:00:00 2001
From: Danny Holman <dholman@gymli.xyz>
Date: Tue, 28 Sep 2021 09:04:01 -0500
Subject: arch: i386: add support for 8259 PIC

Add support for the 8259 programmable interrupt controller.

Signed-off-by: Danny Holman <dholman@gymli.xyz>
---
 arch/i386/boot/boot.s |  3 ++-
 arch/i386/boot/pic.c  | 53 +++++++++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 55 insertions(+), 1 deletion(-)
 create mode 100644 arch/i386/boot/pic.c

(limited to 'arch/i386/boot')

diff --git a/arch/i386/boot/boot.s b/arch/i386/boot/boot.s
index e0005bb..c62abbf 100644
--- a/arch/i386/boot/boot.s
+++ b/arch/i386/boot/boot.s
@@ -45,7 +45,7 @@ _start:
         loop 1b
 
 3:      movl $(0x000B8000 | 0x003), boot_page_table0 - 0xC0000000 + 1023 * 4
-        
+
         movl $(boot_page_table0 - 0xC0000000 + 0x003), boot_page_directory - 0xC0000000
         movl $(boot_page_table0 - 0xC0000000 + 0x003), boot_page_directory - 0xC0000000 + 768 * 4
 
@@ -70,6 +70,7 @@ _start:
 
         call gdt_install
         call idt_install
+        call pic_remap
 
         call kernel_main
 
diff --git a/arch/i386/boot/pic.c b/arch/i386/boot/pic.c
new file mode 100644
index 0000000..f103b92
--- /dev/null
+++ b/arch/i386/boot/pic.c
@@ -0,0 +1,53 @@
+#include <kernel/pic.h>
+
+void pic_eoi(unsigned char irq) {
+        if (irq >= 8)
+                outb(PIC2_COMMAND, 0x20);
+        outb(PIC1_COMMAND, 0x20);
+}
+
+void pic_remap(void) {
+        unsigned char a1 = inb(PIC1_DATA);
+        unsigned char a2 = inb(PIC2_DATA);
+
+        outb(PIC1_COMMAND, ICW1_INIT | ICW1_ICW4);
+        outb(PIC2_COMMAND, ICW1_INIT | ICW1_ICW4);
+        outb(PIC1_DATA, PIC1);
+        outb(PIC2_DATA, PIC2);
+        outb(PIC1_DATA, 4);
+        outb(PIC2_DATA, 2);
+        outb(PIC1_DATA, ICW4_8086);
+        outb(PIC2_DATA, ICW4_8086);
+        outb(PIC1_DATA, a1);
+        outb(PIC2_DATA, a2);
+}
+
+void irq_set_mask(uint8_t irq) {
+        uint16_t port;
+        uint8_t data;
+
+        if (irq < 8) {
+                port = PIC1_DATA;
+        } else {
+                port = PIC2_DATA;
+                irq -= 8;
+        }
+
+        data = inb(port) | (1 << irq);
+        outb(port, data);
+}
+
+void irq_clear_mask(unsigned char irq) {
+        uint16_t port;
+        uint8_t data;
+
+        if (irq < 8) {
+                port = PIC1_DATA;
+        } else {
+                port = PIC2_DATA;
+                irq -= 8;
+        }
+
+        data = inb(port) & ~(1 << irq);
+        outb(port, data);
+}
-- 
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