summaryrefslogtreecommitdiff
path: root/arch/x86/kernel/i8259.c
diff options
context:
space:
mode:
Diffstat (limited to 'arch/x86/kernel/i8259.c')
-rw-r--r--arch/x86/kernel/i8259.c337
1 files changed, 337 insertions, 0 deletions
diff --git a/arch/x86/kernel/i8259.c b/arch/x86/kernel/i8259.c
new file mode 100644
index 000000000000..dc92b49d9204
--- /dev/null
+++ b/arch/x86/kernel/i8259.c
@@ -0,0 +1,337 @@
+#include <linux/linkage.h>
+#include <linux/errno.h>
+#include <linux/signal.h>
+#include <linux/sched.h>
+#include <linux/ioport.h>
+#include <linux/interrupt.h>
+#include <linux/timex.h>
+#include <linux/slab.h>
+#include <linux/random.h>
+#include <linux/init.h>
+#include <linux/kernel_stat.h>
+#include <linux/sysdev.h>
+#include <linux/bitops.h>
+
+#include <asm/acpi.h>
+#include <asm/atomic.h>
+#include <asm/system.h>
+#include <asm/io.h>
+#include <asm/timer.h>
+#include <asm/hw_irq.h>
+#include <asm/pgtable.h>
+#include <asm/delay.h>
+#include <asm/desc.h>
+#include <asm/apic.h>
+#include <asm/arch_hooks.h>
+#include <asm/i8259.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.
+ */
+
+static int i8259A_auto_eoi;
+DEFINE_SPINLOCK(i8259A_lock);
+static void mask_and_ack_8259A(unsigned int);
+
+struct irq_chip i8259A_chip = {
+ .name = "XT-PIC",
+ .mask = disable_8259A_irq,
+ .disable = disable_8259A_irq,
+ .unmask = enable_8259A_irq,
+ .mask_ack = mask_and_ack_8259A,
+};
+
+/*
+ * 8259A PIC functions to handle ISA devices:
+ */
+
+/*
+ * This contains the irq mask for both 8259A irq controllers,
+ */
+unsigned int cached_irq_mask = 0xffff;
+
+/*
+ * Not all IRQs can be routed through the IO-APIC, eg. on certain (older)
+ * boards the timer interrupt is not really connected to any IO-APIC pin,
+ * it's fed to the master 8259A's IR0 line only.
+ *
+ * Any '1' bit in this mask means the IRQ is routed through the IO-APIC.
+ * this 'mixed mode' IRQ handling costs nothing because it's only used
+ * at IRQ setup time.
+ */
+unsigned long io_apic_irqs;
+
+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_slave_mask, PIC_SLAVE_IMR);
+ else
+ outb(cached_master_mask, PIC_MASTER_IMR);
+ 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_slave_mask, PIC_SLAVE_IMR);
+ else
+ outb(cached_master_mask, PIC_MASTER_IMR);
+ 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(PIC_MASTER_CMD) & mask;
+ else
+ ret = inb(PIC_SLAVE_CMD) & (mask >> 8);
+ spin_unlock_irqrestore(&i8259A_lock, flags);
+
+ return ret;
+}
+
+void make_8259A_irq(unsigned int irq)
+{
+ disable_irq_nosync(irq);
+ io_apic_irqs &= ~(1<<irq);
+ set_irq_chip_and_handler_name(irq, &i8259A_chip, handle_level_irq,
+ "XT");
+ 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, PIC_MASTER_CMD); /* ISR register */
+ value = inb(PIC_MASTER_CMD) & irqmask;
+ outb(0x0A, PIC_MASTER_CMD); /* back to the IRR register */
+ return value;
+ }
+ outb(0x0B, PIC_SLAVE_CMD); /* ISR register */
+ value = inb(PIC_SLAVE_CMD) & (irqmask >> 8);
+ outb(0x0A, PIC_SLAVE_CMD); /* 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!
+ */
+static 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 unnecessarily.
+ *
+ * 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(PIC_SLAVE_IMR); /* DUMMY - (do we need this?) */
+ outb(cached_slave_mask, PIC_SLAVE_IMR);
+ /* 'Specific EOI' to slave */
+ outb(0x60+(irq&7), PIC_SLAVE_CMD);
+ /* 'Specific EOI' to master-IRQ2 */
+ outb(0x60+PIC_CASCADE_IR, PIC_MASTER_CMD);
+ } else {
+ inb(PIC_MASTER_IMR); /* DUMMY - (do we need this?) */
+ outb(cached_master_mask, PIC_MASTER_IMR);
+ outb(0x60+irq, PIC_MASTER_CMD); /* '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;
+ /*
+ * 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 char irq_trigger[2];
+/**
+ * ELCR registers (0x4d0, 0x4d1) control edge/level of IRQ
+ */
+static void restore_ELCR(char *trigger)
+{
+ outb(trigger[0], 0x4d0);
+ outb(trigger[1], 0x4d1);
+}
+
+static void save_ELCR(char *trigger)
+{
+ /* IRQ 0,1,2,8,13 are marked as reserved */
+ trigger[0] = inb(0x4d0) & 0xF8;
+ trigger[1] = inb(0x4d1) & 0xDE;
+}
+
+static int i8259A_resume(struct sys_device *dev)
+{
+ init_8259A(i8259A_auto_eoi);
+ restore_ELCR(irq_trigger);
+ return 0;
+}
+
+static int i8259A_suspend(struct sys_device *dev, pm_message_t state)
+{
+ save_ELCR(irq_trigger);
+ return 0;
+}
+
+static int i8259A_shutdown(struct sys_device *dev)
+{
+ /* Put the i8259A into a quiescent state that
+ * the kernel initialization code can get it
+ * out of.
+ */
+ outb(0xff, PIC_MASTER_IMR); /* mask all of 8259A-1 */
+ outb(0xff, PIC_SLAVE_IMR); /* mask all of 8259A-1 */
+ return 0;
+}
+
+static struct sysdev_class i8259_sysdev_class = {
+ .name = "i8259",
+ .suspend = i8259A_suspend,
+ .resume = i8259A_resume,
+ .shutdown = i8259A_shutdown,
+};
+
+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_8259A(int auto_eoi)
+{
+ unsigned long flags;
+
+ i8259A_auto_eoi = auto_eoi;
+
+ spin_lock_irqsave(&i8259A_lock, flags);
+
+ outb(0xff, PIC_MASTER_IMR); /* mask all of 8259A-1 */
+ outb(0xff, PIC_SLAVE_IMR); /* mask all of 8259A-2 */
+
+ /*
+ * outb_pic - this has to work on a wide range of PC hardware.
+ */
+ outb_pic(0x11, PIC_MASTER_CMD); /* ICW1: select 8259A-1 init */
+
+ /* ICW2: 8259A-1 IR0-7 mapped to 0x30-0x37 on x86-64,
+ to 0x20-0x27 on i386 */
+ outb_pic(IRQ0_VECTOR, PIC_MASTER_IMR);
+
+ /* 8259A-1 (the master) has a slave on IR2 */
+ outb_pic(1U << PIC_CASCADE_IR, PIC_MASTER_IMR);
+
+ if (auto_eoi) /* master does Auto EOI */
+ outb_pic(MASTER_ICW4_DEFAULT | PIC_ICW4_AEOI, PIC_MASTER_IMR);
+ else /* master expects normal EOI */
+ outb_pic(MASTER_ICW4_DEFAULT, PIC_MASTER_IMR);
+
+ outb_pic(0x11, PIC_SLAVE_CMD); /* ICW1: select 8259A-2 init */
+
+ /* ICW2: 8259A-2 IR0-7 mapped to IRQ8_VECTOR */
+ outb_pic(IRQ8_VECTOR, PIC_SLAVE_IMR);
+ /* 8259A-2 is a slave on master's IR2 */
+ outb_pic(PIC_CASCADE_IR, PIC_SLAVE_IMR);
+ /* (slave's support for AEOI in flat mode is to be investigated) */
+ outb_pic(SLAVE_ICW4_DEFAULT, PIC_SLAVE_IMR);
+
+ if (auto_eoi)
+ /*
+ * In AEOI mode we just have to mask the interrupt
+ * when acking.
+ */
+ i8259A_chip.mask_ack = disable_8259A_irq;
+ else
+ i8259A_chip.mask_ack = mask_and_ack_8259A;
+
+ udelay(100); /* wait for 8259A to initialize */
+
+ outb(cached_master_mask, PIC_MASTER_IMR); /* restore master IRQ mask */
+ outb(cached_slave_mask, PIC_SLAVE_IMR); /* restore slave IRQ mask */
+
+ spin_unlock_irqrestore(&i8259A_lock, flags);
+}