New i2859 interrupt handling, code is not yet live.

1 files changed, 298 insertions, 0 deletions

diff --git a/arch/mips/kernel/i8259.c b/arch/mips/kernel/i8259.c
new file mode 100644
index 000000000..3e6c630be
--- /dev/null
+++ b/arch/mips/kernel/i8259.c
@@ -0,0 +1,298 @@
+/*
+ * This file is subject to the terms and conditions of the GNU General Public
+ * License.  See the file "COPYING" in the main directory of this archive
+ * for more details.
+ *
+ * Code to handle x86 style IRQs plus some generic interrupt stuff.
+ *
+ * Copyright (C) 1992 Linus Torvalds
+ * Copyright (C) 1994 - 2000 Ralf Baechle
+ */
+#include <linux/delay.h>
+#include <linux/init.h>
+#include <linux/ioport.h>
+#include <linux/irq.h>
+#include <linux/interrupt.h>
+#include <linux/kernel.h>
+#include <linux/spinlock.h>
+
+#include <asm/io.h>
+
+/*
+ * This is the 'legacy' 8259A Programmable Interrupt Controller,
+ * present in the majority of PC/AT boxes.
+ * plus some generic x86 specific things if generic specifics makes
+ * any sense at all.
+ * this file should become arch/i386/kernel/irq.c when the old irq.c
+ * moves to arch independent land
+ */
+
+spinlock_t i8259A_lock = SPIN_LOCK_UNLOCKED;
+
+static void end_8259A_irq (unsigned int irq)
+{
+	if (!(irq_desc[irq].status & (IRQ_DISABLED|IRQ_INPROGRESS)))
+		enable_8259A_irq(irq);
+}
+
+#define shutdown_8259A_irq	disable_8259A_irq
+
+void mask_and_ack_8259A(unsigned int);
+
+static unsigned int startup_8259A_irq(unsigned int irq)
+{ 
+	enable_8259A_irq(irq);
+	return 0; /* never anything pending */
+}
+
+static struct hw_interrupt_type i8259A_irq_type = {
+	"XT-PIC",
+	startup_8259A_irq,
+	shutdown_8259A_irq,
+	enable_8259A_irq,
+	disable_8259A_irq,
+	mask_and_ack_8259A,
+	end_8259A_irq,
+	NULL
+};
+
+/*
+ * 8259A PIC functions to handle ISA devices:
+ */
+
+/*
+ * This contains the irq mask for both 8259A irq controllers,
+ */
+static unsigned int cached_irq_mask = 0xffff;
+
+#define __byte(x,y) 	(((unsigned char *)&(y))[x])
+#define cached_21	(__byte(0,cached_irq_mask))
+#define cached_A1	(__byte(1,cached_irq_mask))
+
+void disable_8259A_irq(unsigned int irq)
+{
+	unsigned int mask = 1 << irq;
+	unsigned long flags;
+
+	spin_lock_irqsave(&i8259A_lock, flags);
+	cached_irq_mask |= mask;
+	if (irq & 8)
+		outb(cached_A1,0xA1);
+	else
+		outb(cached_21,0x21);
+	spin_unlock_irqrestore(&i8259A_lock, flags);
+}
+
+void enable_8259A_irq(unsigned int irq)
+{
+	unsigned int mask = ~(1 << irq);
+	unsigned long flags;
+
+	spin_lock_irqsave(&i8259A_lock, flags);
+	cached_irq_mask &= mask;
+	if (irq & 8)
+		outb(cached_A1,0xA1);
+	else
+		outb(cached_21,0x21);
+	spin_unlock_irqrestore(&i8259A_lock, flags);
+}
+
+int i8259A_irq_pending(unsigned int irq)
+{
+	unsigned int mask = 1<<irq;
+	unsigned long flags;
+	int ret;
+
+	spin_lock_irqsave(&i8259A_lock, flags);
+	if (irq < 8)
+		ret = inb(0x20) & mask;
+	else
+		ret = inb(0xA0) & (mask >> 8);
+	spin_unlock_irqrestore(&i8259A_lock, flags);
+
+	return ret;
+}
+
+void make_8259A_irq(unsigned int irq)
+{
+	disable_irq_nosync(irq);
+	irq_desc[irq].handler = &i8259A_irq_type;
+	enable_irq(irq);
+}
+
+/*
+ * This function assumes to be called rarely. Switching between
+ * 8259A registers is slow.
+ * This has to be protected by the irq controller spinlock
+ * before being called.
+ */
+static inline int i8259A_irq_real(unsigned int irq)
+{
+	int value;
+	int irqmask = 1<<irq;
+
+	if (irq < 8) {
+		outb(0x0B,0x20);		/* ISR register */
+		value = inb(0x20) & irqmask;
+		outb(0x0A,0x20);		/* back to the IRR register */
+		return value;
+	}
+	outb(0x0B,0xA0);		/* ISR register */
+	value = inb(0xA0) & (irqmask >> 8);
+	outb(0x0A,0xA0);		/* back to the IRR register */
+	return value;
+}
+
+/*
+ * Careful! The 8259A is a fragile beast, it pretty
+ * much _has_ to be done exactly like this (mask it
+ * first, _then_ send the EOI, and the order of EOI
+ * to the two 8259s is important!
+ */
+void mask_and_ack_8259A(unsigned int irq)
+{
+	unsigned int irqmask = 1 << irq;
+	unsigned long flags;
+
+	spin_lock_irqsave(&i8259A_lock, flags);
+	/*
+	 * Lightweight spurious IRQ detection. We do not want
+	 * to overdo spurious IRQ handling - it's usually a sign
+	 * of hardware problems, so we only do the checks we can
+	 * do without slowing down good hardware unnecesserily.
+	 *
+	 * Note that IRQ7 and IRQ15 (the two spurious IRQs
+	 * usually resulting from the 8259A-1|2 PICs) occur
+	 * even if the IRQ is masked in the 8259A. Thus we
+	 * can check spurious 8259A IRQs without doing the
+	 * quite slow i8259A_irq_real() call for every IRQ.
+	 * This does not cover 100% of spurious interrupts,
+	 * but should be enough to warn the user that there
+	 * is something bad going on ...
+	 */
+	if (cached_irq_mask & irqmask)
+		goto spurious_8259A_irq;
+	cached_irq_mask |= irqmask;
+
+handle_real_irq:
+	if (irq & 8) {
+		inb(0xA1);		/* DUMMY - (do we need this?) */
+		outb(cached_A1,0xA1);
+		outb(0x60+(irq&7),0xA0);/* 'Specific EOI' to slave */
+		outb(0x62,0x20);	/* 'Specific EOI' to master-IRQ2 */
+	} else {
+		inb(0x21);		/* DUMMY - (do we need this?) */
+		outb(cached_21,0x21);
+		outb(0x60+irq,0x20);	/* 'Specific EOI' to master */
+	}
+	spin_unlock_irqrestore(&i8259A_lock, flags);
+	return;
+
+spurious_8259A_irq:
+	/*
+	 * this is the slow path - should happen rarely.
+	 */
+	if (i8259A_irq_real(irq))
+		/*
+		 * oops, the IRQ _is_ in service according to the
+		 * 8259A - not spurious, go handle it.
+		 */
+		goto handle_real_irq;
+
+	{
+		static int spurious_irq_mask = 0;
+		/*
+		 * At this point we can be sure the IRQ is spurious,
+		 * lets ACK and report it. [once per IRQ]
+		 */
+		if (!(spurious_irq_mask & irqmask)) {
+			printk("spurious 8259A interrupt: IRQ%d.\n", irq);
+			spurious_irq_mask |= irqmask;
+		}
+		irq_err_count++;
+		/*
+		 * Theoretically we do not have to handle this IRQ,
+		 * but in Linux this does not cause problems and is
+		 * simpler for us.
+		 */
+		goto handle_real_irq;
+	}
+}
+
+void __init init_8259A(int auto_eoi)
+{
+	unsigned long flags;
+
+	spin_lock_irqsave(&i8259A_lock, flags);
+
+	outb(0xff, 0x21);	/* mask all of 8259A-1 */
+	outb(0xff, 0xA1);	/* mask all of 8259A-2 */
+
+	/*
+	 * outb_p - this has to work on a wide range of PC hardware.
+	 */
+	outb_p(0x11, 0x20);	/* ICW1: select 8259A-1 init */
+	outb_p(0x20 + 0, 0x21);	/* ICW2: 8259A-1 IR0-7 mapped to 0x20-0x27 */
+	outb_p(0x04, 0x21);	/* 8259A-1 (the master) has a slave on IR2 */
+	if (auto_eoi)
+		outb_p(0x03, 0x21);	/* master does Auto EOI */
+	else
+		outb_p(0x01, 0x21);	/* master expects normal EOI */
+
+	outb_p(0x11, 0xA0);	/* ICW1: select 8259A-2 init */
+	outb_p(0x20 + 8, 0xA1);	/* ICW2: 8259A-2 IR0-7 mapped to 0x28-0x2f */
+	outb_p(0x02, 0xA1);	/* 8259A-2 is a slave on master's IR2 */
+	outb_p(0x01, 0xA1);	/* (slave's support for AEOI in flat mode
+				    is to be investigated) */
+
+	if (auto_eoi)
+		/*
+		 * in AEOI mode we just have to mask the interrupt
+		 * when acking.
+		 */
+		i8259A_irq_type.ack = disable_8259A_irq;
+	else
+		i8259A_irq_type.ack = mask_and_ack_8259A;
+
+	udelay(100);		/* wait for 8259A to initialize */
+
+	outb(cached_21, 0x21);	/* restore master IRQ mask */
+	outb(cached_A1, 0xA1);	/* restore slave IRQ mask */
+
+	spin_unlock_irqrestore(&i8259A_lock, flags);
+}
+
+/*
+ * IRQ2 is cascade interrupt to second interrupt controller
+ */
+static struct irqaction irq2 = { no_action, 0, 0, "cascade", NULL, NULL};
+
+/*
+ * On systems with i8259-style interrupt controllers we assume for
+ * driver compatibility reasons interrupts 0 - 15 to be the i8295
+ * interrupts even if the hardware uses a different interrupt numbering.
+ */
+void __init init_i8259_irqs (void)
+{
+	int i;
+
+	request_region(0x20,0x20, "pic1");
+	request_region(0xa0,0x20, "pic2");
+	setup_irq(2, &irq2);
+
+	init_8259A(0);
+
+	for (i = 0; i < 16; i++) {
+		irq_desc[i].status = IRQ_DISABLED;
+		irq_desc[i].action = 0;
+		irq_desc[i].depth = 1;
+		irq_desc[i].handler = &i8259A_irq_type;
+	}
+
+	/*
+	 * IRQ0 seems to be the irq for PC style stuff.
+	 * I don't know how to handle the debug button interrupt, so
+	 * don't use this button yet or bad things happen ...
+	 */
+	set_cp0_status(ST0_IM, IE_IRQ1 | IE_IRQ3 | IE_IRQ4);
+}