1 files changed, 455 insertions, 0 deletions
diff --git a/arch/x86/kernel/i8259.c b/arch/x86/kernel/i8259.c
new file mode 100644
index 0000000000..c20d1832c4
--- /dev/null
+++ b/arch/x86/kernel/i8259.c
@@ -0,0 +1,455 @@
+// SPDX-License-Identifier: GPL-2.0
+#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/irq.h>
+#include <linux/timex.h>
+#include <linux/random.h>
+#include <linux/init.h>
+#include <linux/kernel_stat.h>
+#include <linux/syscore_ops.h>
+#include <linux/bitops.h>
+#include <linux/acpi.h>
+#include <linux/io.h>
+#include <linux/delay.h>
+#include <linux/pgtable.h>
+
+#include <linux/atomic.h>
+#include <asm/timer.h>
+#include <asm/hw_irq.h>
+#include <asm/desc.h>
+#include <asm/apic.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 void init_8259A(int auto_eoi);
+
+static bool pcat_compat __ro_after_init;
+static int i8259A_auto_eoi;
+DEFINE_RAW_SPINLOCK(i8259A_lock);
+
+/*
+ * 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;
+
+static void mask_8259A_irq(unsigned int irq)
+{
+	unsigned int mask = 1 << irq;
+	unsigned long flags;
+
+	raw_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);
+	raw_spin_unlock_irqrestore(&i8259A_lock, flags);
+}
+
+static void disable_8259A_irq(struct irq_data *data)
+{
+	mask_8259A_irq(data->irq);
+}
+
+static void unmask_8259A_irq(unsigned int irq)
+{
+	unsigned int mask = ~(1 << irq);
+	unsigned long flags;
+
+	raw_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);
+	raw_spin_unlock_irqrestore(&i8259A_lock, flags);
+}
+
+static void enable_8259A_irq(struct irq_data *data)
+{
+	unmask_8259A_irq(data->irq);
+}
+
+static int i8259A_irq_pending(unsigned int irq)
+{
+	unsigned int mask = 1<<irq;
+	unsigned long flags;
+	int ret;
+
+	raw_spin_lock_irqsave(&i8259A_lock, flags);
+	if (irq < 8)
+		ret = inb(PIC_MASTER_CMD) & mask;
+	else
+		ret = inb(PIC_SLAVE_CMD) & (mask >> 8);
+	raw_spin_unlock_irqrestore(&i8259A_lock, flags);
+
+	return ret;
+}
+
+static void make_8259A_irq(unsigned int irq)
+{
+	disable_irq_nosync(irq);
+	io_apic_irqs &= ~(1<<irq);
+	irq_set_chip_and_handler(irq, &i8259A_chip, handle_level_irq);
+	irq_set_status_flags(irq, IRQ_LEVEL);
+	enable_irq(irq);
+	lapic_assign_legacy_vector(irq, true);
+}
+
+/*
+ * 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(struct irq_data *data)
+{
+	unsigned int irq = data->irq;
+	unsigned int irqmask = 1 << irq;
+	unsigned long flags;
+
+	raw_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 */
+	}
+	raw_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_deferred(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;
+	}
+}
+
+struct irq_chip i8259A_chip = {
+	.name		= "XT-PIC",
+	.irq_mask	= disable_8259A_irq,
+	.irq_disable	= disable_8259A_irq,
+	.irq_unmask	= enable_8259A_irq,
+	.irq_mask_ack	= mask_and_ack_8259A,
+};
+
+static char irq_trigger[2];
+/* ELCR registers (0x4d0, 0x4d1) control edge/level of IRQ */
+static void restore_ELCR(char *trigger)
+{
+	outb(trigger[0], PIC_ELCR1);
+	outb(trigger[1], PIC_ELCR2);
+}
+
+static void save_ELCR(char *trigger)
+{
+	/* IRQ 0,1,2,8,13 are marked as reserved */
+	trigger[0] = inb(PIC_ELCR1) & 0xF8;
+	trigger[1] = inb(PIC_ELCR2) & 0xDE;
+}
+
+static void i8259A_resume(void)
+{
+	init_8259A(i8259A_auto_eoi);
+	restore_ELCR(irq_trigger);
+}
+
+static int i8259A_suspend(void)
+{
+	save_ELCR(irq_trigger);
+	return 0;
+}
+
+static void i8259A_shutdown(void)
+{
+	/* 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-2 */
+}
+
+static struct syscore_ops i8259_syscore_ops = {
+	.suspend = i8259A_suspend,
+	.resume = i8259A_resume,
+	.shutdown = i8259A_shutdown,
+};
+
+static void mask_8259A(void)
+{
+	unsigned long flags;
+
+	raw_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 */
+
+	raw_spin_unlock_irqrestore(&i8259A_lock, flags);
+}
+
+static void unmask_8259A(void)
+{
+	unsigned long flags;
+
+	raw_spin_lock_irqsave(&i8259A_lock, flags);
+
+	outb(cached_master_mask, PIC_MASTER_IMR); /* restore master IRQ mask */
+	outb(cached_slave_mask, PIC_SLAVE_IMR);	  /* restore slave IRQ mask */
+
+	raw_spin_unlock_irqrestore(&i8259A_lock, flags);
+}
+
+static int probe_8259A(void)
+{
+	unsigned char new_val, probe_val = ~(1 << PIC_CASCADE_IR);
+	unsigned long flags;
+
+	/*
+	 * If MADT has the PCAT_COMPAT flag set, then do not bother probing
+	 * for the PIC. Some BIOSes leave the PIC uninitialized and probing
+	 * fails.
+	 *
+	 * Right now this causes problems as quite some code depends on
+	 * nr_legacy_irqs() > 0 or has_legacy_pic() == true. This is silly
+	 * when the system has an IO/APIC because then PIC is not required
+	 * at all, except for really old machines where the timer interrupt
+	 * must be routed through the PIC. So just pretend that the PIC is
+	 * there and let legacy_pic->init() initialize it for nothing.
+	 *
+	 * Alternatively this could just try to initialize the PIC and
+	 * repeat the probe, but for cases where there is no PIC that's
+	 * just pointless.
+	 */
+	if (pcat_compat)
+		return nr_legacy_irqs();
+
+	/*
+	 * Check to see if we have a PIC.  Mask all except the cascade and
+	 * read back the value we just wrote. If we don't have a PIC, we
+	 * will read 0xff as opposed to the value we wrote.
+	 */
+	raw_spin_lock_irqsave(&i8259A_lock, flags);
+
+	outb(0xff, PIC_SLAVE_IMR);	/* mask all of 8259A-2 */
+	outb(probe_val, PIC_MASTER_IMR);
+	new_val = inb(PIC_MASTER_IMR);
+	if (new_val != probe_val) {
+		printk(KERN_INFO "Using NULL legacy PIC\n");
+		legacy_pic = &null_legacy_pic;
+	}
+
+	raw_spin_unlock_irqrestore(&i8259A_lock, flags);
+	return nr_legacy_irqs();
+}
+
+static void init_8259A(int auto_eoi)
+{
+	unsigned long flags;
+
+	i8259A_auto_eoi = auto_eoi;
+
+	raw_spin_lock_irqsave(&i8259A_lock, flags);
+
+	outb(0xff, PIC_MASTER_IMR);	/* mask all of 8259A-1 */
+
+	/*
+	 * 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 ISA_IRQ_VECTOR(0) */
+	outb_pic(ISA_IRQ_VECTOR(0), 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 ISA_IRQ_VECTOR(8) */
+	outb_pic(ISA_IRQ_VECTOR(8), 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.irq_mask_ack = disable_8259A_irq;
+	else
+		i8259A_chip.irq_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 */
+
+	raw_spin_unlock_irqrestore(&i8259A_lock, flags);
+}
+
+/*
+ * make i8259 a driver so that we can select pic functions at run time. the goal
+ * is to make x86 binary compatible among pc compatible and non-pc compatible
+ * platforms, such as x86 MID.
+ */
+
+static void legacy_pic_noop(void) { };
+static void legacy_pic_uint_noop(unsigned int unused) { };
+static void legacy_pic_int_noop(int unused) { };
+static int legacy_pic_irq_pending_noop(unsigned int irq)
+{
+	return 0;
+}
+static int legacy_pic_probe(void)
+{
+	return 0;
+}
+
+struct legacy_pic null_legacy_pic = {
+	.nr_legacy_irqs = 0,
+	.chip = &dummy_irq_chip,
+	.mask = legacy_pic_uint_noop,
+	.unmask = legacy_pic_uint_noop,
+	.mask_all = legacy_pic_noop,
+	.restore_mask = legacy_pic_noop,
+	.init = legacy_pic_int_noop,
+	.probe = legacy_pic_probe,
+	.irq_pending = legacy_pic_irq_pending_noop,
+	.make_irq = legacy_pic_uint_noop,
+};
+
+static struct legacy_pic default_legacy_pic = {
+	.nr_legacy_irqs = NR_IRQS_LEGACY,
+	.chip  = &i8259A_chip,
+	.mask = mask_8259A_irq,
+	.unmask = unmask_8259A_irq,
+	.mask_all = mask_8259A,
+	.restore_mask = unmask_8259A,
+	.init = init_8259A,
+	.probe = probe_8259A,
+	.irq_pending = i8259A_irq_pending,
+	.make_irq = make_8259A_irq,
+};
+
+struct legacy_pic *legacy_pic = &default_legacy_pic;
+EXPORT_SYMBOL(legacy_pic);
+
+static int __init i8259A_init_ops(void)
+{
+	if (legacy_pic == &default_legacy_pic)
+		register_syscore_ops(&i8259_syscore_ops);
+
+	return 0;
+}
+device_initcall(i8259A_init_ops);
+
+void __init legacy_pic_pcat_compat(void)
+{
+	pcat_compat = true;
+}