/*
* i8259 interrupt controller driver.
*
* 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; either version
* 2 of the License, or (at your option) any later version.
*/
#include <linux/init.h>
#include <linux/ioport.h>
#include <linux/interrupt.h>
#include <asm/io.h>
#include <asm/i8259.h>
static volatile void __iomem *pci_intack; /* RO, gives us the irq vector */
static unsigned char cached_8259[2] = { 0xff, 0xff };
#define cached_A1 (cached_8259[0])
#define cached_21 (cached_8259[1])
static DEFINE_SPINLOCK(i8259_lock);
static int i8259_pic_irq_offset;
/*
* Acknowledge the IRQ using either the PCI host bridge's interrupt
* acknowledge feature or poll. How i8259_init() is called determines
* which is called. It should be noted that polling is broken on some
* IBM and Motorola PReP boxes so we must use the int-ack feature on them.
*/
int i8259_irq(struct pt_regs *regs)
{
int irq;
spin_lock(&i8259_lock);
/* Either int-ack or poll for the IRQ */
if (pci_intack)
irq = readb(pci_intack);
else {
/* Perform an interrupt acknowledge cycle on controller 1. */
outb(0x0C, 0x20); /* prepare for poll */
irq = inb(0x20) & 7;
if (irq == 2 ) {
/*
* Interrupt is cascaded so perform interrupt
* acknowledge on controller 2.
*/
outb(0x0C, 0xA0); /* prepare for poll */
irq = (inb(0xA0) & 7) + 8;
}
}
if (irq == 7) {
/*
* This may be a spurious interrupt.
*
* Read the interrupt status register (ISR). If the most
* significant bit is not set then there is no valid
* interrupt.
*/
if (!pci_intack)
outb(0x0B, 0x20); /* ISR register */
if(~inb(0x20) & 0x80)
irq = -1;
}
spin_unlock(&i8259_lock);
return irq + i8259_pic_irq_offset;
}
int i8259_irq_cascade(struct pt_regs *regs, void *unused)
{
return i8259_irq(regs);
}
static void i8259_mask_and_ack_irq(unsigned int irq_nr)
{
unsigned long flags;
spin_lock_irqsave(&i8259_lock, flags);
irq_nr -= i8259_pic_irq_offset;
if (irq_nr > 7) {
cached_A1 |= 1 << (irq_nr-8);
inb(0xA1); /* DUMMY */
outb(cached_A1, 0xA1);
outb(0x20, 0xA0); /* Non-specific EOI */
outb(0x20, 0x20); /* Non-specific EOI to cascade */
} else {
cached_21 |= 1 << irq_nr;
inb(0x21); /* DUMMY */
outb(cached_21, 0x21);
outb(0x20, 0x20); /* Non-specific EOI */
}
spin_unlock_irqrestore(&i8259_lock, flags);
}
static void i8259_set_irq_mask(int irq_nr)
{
outb(cached_A1,0xA1);
outb(cached_21,0x21);
}
static void i8259_mask_irq(unsigned int irq_nr)
{
unsigned long flags;
spin_lock_irqsave(&i8259_lock, flags);
irq_nr -= i8259_pic_irq_offset;
if (irq_nr < 8)
cached_21 |= 1 << irq_nr;
else
cached_A1 |= 1 << (irq_nr-8);
i8259_set_irq_mask(irq_nr);
spin_unlock_irqrestore(&i8259_lock, flags);
}
static void i8259_unmask_irq(unsigned int irq_nr)
{
unsigned long flags;
spin_lock_irqsave(&i8259_lock, flags);
irq_nr -= i8259_pic_irq_offset;
if (irq_nr < 8)
cached_21 &= ~(1 << irq_nr);
else
cached_A1 &= ~(1 << (irq_nr-8));
i8259_set_irq_mask(irq_nr);
spin_unlock_irqrestore(&i8259_lock, flags);
}
static void i8259_end_irq(unsigned int irq)
{
if (!(irq_desc[irq].status & (IRQ_DISABLED|IRQ_INPROGRESS))
&& irq_desc[irq].action)
i8259_unmask_irq(irq);
}
struct hw_interrupt_type i8259_pic = {
.typename = " i8259 ",
.enable = i8259_unmask_irq,
.disable = i8259_mask_irq,
.ack = i8259_mask_and_ack_irq,
.end = i8259_end_irq,
};
static struct resource pic1_iores = {
.name = "8259 (master)",
.start = 0x20,
.end = 0x21,
.flags = IORESOURCE_BUSY,
};
static struct resource pic2_iores = {
.name = "8259 (slave)",
.start = 0xa0,
.end = 0xa1,
.flags = IORESOURCE_BUSY,
};
static struct resource pic_edgectrl_iores = {
.name = "8259 edge control",
.start = 0x4d0,
.end = 0x4d1,
.flags = IORESOURCE_BUSY,
};
static struct irqaction i8259_irqaction = {
.handler = no_action,
.flags = SA_INTERRUPT,
.mask = CPU_MASK_NONE,
.name = "82c59 secondary cascade",
};
/*
* i8259_init()
* intack_addr - PCI interrupt acknowledge (real) address which will return
* the active irq from the 8259
*/
void __init i8259_init(unsigned long intack_addr, int offset)
{
unsigned long flags;
int i;
spin_lock_irqsave(&i8259_lock, flags);
i8259_pic_irq_offset = offset;
/* init master interrupt controller */
outb(0x11, 0x20); /* Start init sequence */
outb(0x00, 0x21); /* Vector base */
outb(0x04, 0x21); /* edge tiggered, Cascade (slave) on IRQ2 */
outb(0x01, 0x21); /* Select 8086 mode */
/* init slave interrupt controller */
outb(0x11, 0xA0); /* Start init sequence */
outb(0x08, 0xA1); /* Vector base */
outb(0x02, 0xA1); /* edge triggered, Cascade (slave) on IRQ2 */
outb(0x01, 0xA1); /* Select 8086 mode */
/* always read ISR */
outb(0x0B, 0x20);
outb(0x0B, 0xA0);
/* Mask all interrupts */
outb(cached_A1, 0xA1);
outb(cached_21, 0x21);
spin_unlock_irqrestore(&i8259_lock, flags);
/* reserve our resources */
setup_irq(offset + 2, &i8259_irqaction);
request_resource(&ioport_resource, &pic1_iores);
request_resource(&ioport_resource, &pic2_iores);
request_resource(&ioport_resource, &pic_edgectrl_iores);
if (intack_addr != 0)
pci_intack = ioremap(intack_addr, 1);
for (i = 0; i < NUM_ISA_INTERRUPTS; ++i)
irq_desc[offset + i].handler = &i8259_pic;
}
