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authorLinus Torvalds <torvalds@ppc970.osdl.org>2005-04-16 15:20:36 -0700
committerLinus Torvalds <torvalds@ppc970.osdl.org>2005-04-16 15:20:36 -0700
commit1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 (patch)
tree0bba044c4ce775e45a88a51686b5d9f90697ea9d /arch/mips/kernel/i8259.c
downloadlinux-sh-1da177e4c3f41524e886b7f1b8a0c1fc7321cac2.tar.gz
Linux-2.6.12-rc2v2.6.12-rc2
Initial git repository build. I'm not bothering with the full history, even though we have it. We can create a separate "historical" git archive of that later if we want to, and in the meantime it's about 3.2GB when imported into git - space that would just make the early git days unnecessarily complicated, when we don't have a lot of good infrastructure for it. Let it rip!
Diffstat (limited to 'arch/mips/kernel/i8259.c')
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diff --git a/arch/mips/kernel/i8259.c b/arch/mips/kernel/i8259.c
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+/*
+ * 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/interrupt.h>
+#include <linux/kernel.h>
+#include <linux/spinlock.h>
+#include <linux/sysdev.h>
+
+#include <asm/i8259.h>
+#include <asm/io.h>
+
+void enable_8259A_irq(unsigned int irq);
+void disable_8259A_irq(unsigned int irq);
+
+/*
+ * 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)) &&
+ irq_desc[irq].action)
+ 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 cached_21 (cached_irq_mask)
+#define cached_A1 (cached_irq_mask >> 8)
+
+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
+ * nnecesserily.
+ *
+ * Note that IRQ7 and IRQ15 (the two spurious IRQs usually resulting
+ * rom 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(KERN_DEBUG "spurious 8259A interrupt: IRQ%d.\n", irq);
+ spurious_irq_mask |= irqmask;
+ }
+ atomic_inc(&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;
+ }
+}
+
+static int i8259A_resume(struct sys_device *dev)
+{
+ init_8259A(0);
+ return 0;
+}
+
+static struct sysdev_class i8259_sysdev_class = {
+ set_kset_name("i8259"),
+ .resume = i8259A_resume,
+};
+
+static struct sys_device device_i8259A = {
+ .id = 0,
+ .cls = &i8259_sysdev_class,
+};
+
+static int __init i8259A_init_sysfs(void)
+{
+ int error = sysdev_class_register(&i8259_sysdev_class);
+ if (!error)
+ error = sysdev_register(&device_i8259A);
+ return error;
+}
+
+device_initcall(i8259A_init_sysfs);
+
+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(0x00, 0x21); /* ICW2: 8259A-1 IR0-7 mapped to 0x00-0x07 */
+ 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(0x08, 0xA1); /* ICW2: 8259A-2 IR0-7 mapped to 0x08-0x0f */
+ 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, CPU_MASK_NONE, "cascade", NULL, NULL
+};
+
+static struct resource pic1_io_resource = {
+ "pic1", 0x20, 0x3f, IORESOURCE_BUSY
+};
+
+static struct resource pic2_io_resource = {
+ "pic2", 0xa0, 0xbf, IORESOURCE_BUSY
+};
+
+/*
+ * 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_resource(&ioport_resource, &pic1_io_resource);
+ request_resource(&ioport_resource, &pic2_io_resource);
+
+ 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;
+ }
+
+ setup_irq(2, &irq2);
+}