diff options
Diffstat (limited to 'picirq.c')
| -rw-r--r-- | picirq.c | 70 |
1 files changed, 1 insertions, 69 deletions
@@ -1,5 +1,3 @@ -// Intel 8259A programmable interrupt controllers. - #include "types.h" #include "x86.h" #include "traps.h" @@ -8,79 +6,13 @@ #define IO_PIC1 0x20 // Master (IRQs 0-7) #define IO_PIC2 0xA0 // Slave (IRQs 8-15) -#define IRQ_SLAVE 2 // IRQ at which slave connects to master - -// Current IRQ mask. -// Initial IRQ mask has interrupt 2 enabled (for slave 8259A). -static ushort irqmask = 0xFFFF & ~(1<<IRQ_SLAVE); - -static void -picsetmask(ushort mask) -{ - irqmask = mask; - outb(IO_PIC1+1, mask); - outb(IO_PIC2+1, mask >> 8); -} - -void -picenable(int irq) -{ - picsetmask(irqmask & ~(1<<irq)); -} - -// Initialize the 8259A interrupt controllers. +// Don't use the 8259A interrupt controllers. Xv6 assumes SMP hardware. void picinit(void) { // mask all interrupts outb(IO_PIC1+1, 0xFF); outb(IO_PIC2+1, 0xFF); - - // Set up master (8259A-1) - - // ICW1: 0001g0hi - // g: 0 = edge triggering, 1 = level triggering - // h: 0 = cascaded PICs, 1 = master only - // i: 0 = no ICW4, 1 = ICW4 required - outb(IO_PIC1, 0x11); - - // ICW2: Vector offset - outb(IO_PIC1+1, T_IRQ0); - - // ICW3: (master PIC) bit mask of IR lines connected to slaves - // (slave PIC) 3-bit # of slave's connection to master - outb(IO_PIC1+1, 1<<IRQ_SLAVE); - - // ICW4: 000nbmap - // n: 1 = special fully nested mode - // b: 1 = buffered mode - // m: 0 = slave PIC, 1 = master PIC - // (ignored when b is 0, as the master/slave role - // can be hardwired). - // a: 1 = Automatic EOI mode - // p: 0 = MCS-80/85 mode, 1 = intel x86 mode - outb(IO_PIC1+1, 0x3); - - // Set up slave (8259A-2) - outb(IO_PIC2, 0x11); // ICW1 - outb(IO_PIC2+1, T_IRQ0 + 8); // ICW2 - outb(IO_PIC2+1, IRQ_SLAVE); // ICW3 - // NB Automatic EOI mode doesn't tend to work on the slave. - // Linux source code says it's "to be investigated". - outb(IO_PIC2+1, 0x3); // ICW4 - - // OCW3: 0ef01prs - // ef: 0x = NOP, 10 = clear specific mask, 11 = set specific mask - // p: 0 = no polling, 1 = polling mode - // rs: 0x = NOP, 10 = read IRR, 11 = read ISR - outb(IO_PIC1, 0x68); // clear specific mask - outb(IO_PIC1, 0x0a); // read IRR by default - - outb(IO_PIC2, 0x68); // OCW3 - outb(IO_PIC2, 0x0a); // OCW3 - - if(irqmask != 0xFFFF) - picsetmask(irqmask); } //PAGEBREAK! |