/*
* linux/arch/alpha/kernel/irq_i8259.c
*
* This is the 'legacy' 8259A Programmable Interrupt Controller,
* present in the majority of PC/AT boxes.
*
* Started hacking from linux-2.3.30pre6/arch/i386/kernel/i8259.c.
*/
#include <linux/config.h>
#include <linux/init.h>
#include <linux/cache.h>
#include <linux/sched.h>
#include <linux/irq.h>
#include <linux/interrupt.h>
#include <asm/io.h>
#include "proto.h"
#include "irq_impl.h"
/* Note mask bit is true for DISABLED irqs. */
static unsigned int cached_irq_mask = 0xffff;
static DEFINE_SPINLOCK(i8259_irq_lock);
static inline void
i8259_update_irq_hw(unsigned int irq, unsigned long mask)
{
int port = 0x21;
if (irq & 8) mask >>= 8;
if (irq & 8) port = 0xA1;
outb(mask, port);
}
inline void
i8259a_enable_irq(unsigned int irq)
{
spin_lock(&i8259_irq_lock);
i8259_update_irq_hw(irq, cached_irq_mask &= ~(1 << irq));
spin_unlock(&i8259_irq_lock);
}
static inline void
__i8259a_disable_irq(unsigned int irq)
{
i8259_update_irq_hw(irq, cached_irq_mask |= 1 << irq);
}
void
i8259a_disable_irq(unsigned int irq)
{
spin_lock(&i8259_irq_lock);
__i8259a_disable_irq(irq);
spin_unlock(&i8259_irq_lock);
}
void
i8259a_mask_and_ack_irq(unsigned int irq)
{
spin_lock(&i8259_irq_lock);
__i8259a_disable_irq(irq);
/* Ack the interrupt making it the lowest priority. */
if (irq >= 8) {
outb(0xE0 | (irq - 8), 0xa0); /* ack the slave */
irq = 2;
}
outb(0xE0 | irq, 0x20); /* ack the master */
spin_unlock(&i8259_irq_lock);
}
unsigned int
i8259a_startup_irq(unsigned int irq)
{
i8259a_enable_irq(irq);
return 0; /* never anything pending */
}
void
i8259a_end_irq(unsigned int irq)
{
if (!(irq_desc[irq].status & (IRQ_DISABLED|IRQ_INPROGRESS)))
i8259a_enable_irq(irq);
}
struct hw_interrupt_type i8259a_irq_type = {
.typename = "XT-PIC",
.startup = i8259a_startup_irq,
.shutdown = i8259a_disable_irq,
.enable = i8259a_enable_irq,
.disable = i8259a_disable_irq,
.ack = i8259a_mask_and_ack_irq,
.end = i8259a_end_irq,
};
void __init
init_i8259a_irqs(void)
{
static struct irqaction cascade = {
.handler = no_action,
.name = "cascade",
};
long i;
outb(0xff, 0x21); /* mask all of 8259A-1 */
outb(0xff, 0xA1); /* mask all of 8259A-2 */
for (i = 0; i < 16; i++) {
irq_desc[i].status = IRQ_DISABLED;
irq_desc[i].handler = &i8259a_irq_type;
}
setup_irq(2, &cascade);
}
#if defined(CONFIG_ALPHA_GENERIC)
# define IACK_SC alpha_mv.iack_sc
#elif defined(CONFIG_ALPHA_APECS)
# define IACK_SC APECS_IACK_SC
#elif defined(CONFIG_ALPHA_LCA)
# define IACK_SC LCA_IACK_SC
#elif defined(CONFIG_ALPHA_CIA)
# define IACK_SC CIA_IACK_SC
#elif defined(CONFIG_ALPHA_PYXIS)
# define IACK_SC PYXIS_IACK_SC
#elif defined(CONFIG_ALPHA_TITAN)
# define IACK_SC TITAN_IACK_SC
#elif defined(CONFIG_ALPHA_TSUNAMI)
# define IACK_SC TSUNAMI_IACK_SC
#elif defined(CONFIG_ALPHA_IRONGATE)
# define IACK_SC IRONGATE_IACK_SC
#endif
/* Note that CONFIG_ALPHA_POLARIS is intentionally left out here, since
sys_rx164 wants to use isa_no_iack_sc_device_interrupt for some reason. */
#if defined(IACK_SC)
void
isa_device_interrupt(unsigned long vector, struct pt_regs *regs)
{
/*
* Generate a PCI interrupt acknowledge cycle. The PIC will
* respond with the interrupt vector of the highest priority
* interrupt that is pending. The PALcode sets up the
* interrupts vectors such that irq level L generates vector L.
*/
int j = *(vuip) IACK_SC;
j &= 0xff;
handle_irq(j, regs);
}
#endif
#if defined(CONFIG_ALPHA_GENERIC) || !defined(IACK_SC)
void
isa_no_iack_sc_device_interrupt(unsigned long vector, struct pt_regs *regs)
{
unsigned long pic;
/*
* It seems to me that the probability of two or more *device*
* interrupts occurring at almost exactly the same time is
* pretty low. So why pay the price of checking for
* additional interrupts here if the common case can be
* handled so much easier?
*/
/*
* The first read of gives you *all* interrupting lines.
* Therefore, read the mask register and and out those lines
* not enabled. Note that some documentation has 21 and a1
* write only. This is not true.
*/
pic = inb(0x20) | (inb(0xA0) << 8); /* read isr */
pic &= 0xFFFB; /* mask out cascade & hibits */
while (pic) {
int j = ffz(~pic);
pic &= pic - 1;
handle_irq(j, regs);
}
}
#endif
