Rewrite i386 interrupt handling

Rewrite interrupt handling functionality for the i386 port. Separated
functionality into separate CPU and Architecture components.

It appears as if the i386 interrupt handler functionality was intended
to allow multiple handlers to be installed for a given interrupt.
Unfortunately, this functionality was not fully implemented and also
had the problem that irq_free_handler() does not allow the passing
of the handler function pointer and therefore could never be used to
free specific handlers that had been installed for a given IRQ.

There were also various issues with array bounds not being fully
tested.

I had two objectives in mind for the new implementation:

1) Keep the implementation as similar as possible to existing
   implementations. To that end, I have used the leon2/3
   implementations as the reference

2) Seperate CPU and Architecture specific elements. All specific i386
   interrupt functionality is now in cpu/i386/ with the high level
   API and architecture specific code in lib_i386. Functionality
   specific to the PC/AT architecture (i.e. cascaded i8259 PICs) has
   been further split out into an individual file to allow for the
   implementation of the PIC architecture of the SC520 CPU (supports
   more IRQs)

Signed-off-by: Graeme Russ <graeme.russ at gmail.com>

3 files changed, 326 insertions, 0 deletions

diff --git a/lib_i386/Makefile b/lib_i386/Makefile
index 4fbcd08..fb4184b 100644
--- a/lib_i386/Makefile
+++ b/lib_i386/Makefile
@@ -38,6 +38,8 @@ COBJS-y	+= realmode.o
 COBJS-y	+= video_bios.o
 COBJS-y	+= video.o
 COBJS-y	+= zimage.o
+COBJS-y	+= interrupts.o
+COBJS-$(CONFIG_SYS_PCAT_INTERRUPTS) += pcat_interrupts.o
 
 SRCS	:= $(SOBJS-y:.o=.S) $(COBJS-y:.o=.c)
 OBJS	:= $(addprefix $(obj),$(SOBJS-y) $(COBJS-y))
diff --git a/lib_i386/interrupts.c b/lib_i386/interrupts.c
new file mode 100644
index 0000000..b0f84de
--- /dev/null
+++ b/lib_i386/interrupts.c
@@ -0,0 +1,159 @@
+/*
+ * (C) Copyright 2009
+ * Graeme Russ, graeme.russ@gmail.com
+ *
+ * (C) Copyright 2007
+ * Daniel Hellstrom, Gaisler Research, daniel@gaisler.com
+ *
+ * (C) Copyright 2006
+ * Detlev Zundel, DENX Software Engineering, dzu@denx.de
+ *
+ * (C) Copyright -2003
+ * Wolfgang Denk, DENX Software Engineering, wd@denx.de.
+ *
+ * (C) Copyright 2002
+ * Daniel Engström, Omicron Ceti AB, daniel@omicron.se
+ *
+ * (C) Copyright 2001
+ * Josh Huber <huber@mclx.com>, Mission Critical Linux, Inc.
+ *
+ * See file CREDITS for list of people who contributed to this
+ * project.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License as
+ * published by the Free Software Foundation; either version 2 of
+ * the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place, Suite 330, Boston,
+ * MA 02111-1307 USA
+ */
+
+/*
+ * This file contains the high-level API for the interrupt sub-system
+ * of the i386 port of U-Boot. Most of the functionality has been
+ * shamelessly stolen from the leon2 / leon3 ports of U-Boot.
+ * Daniel Hellstrom, Detlev Zundel, Wolfgang Denk and Josh Huber are
+ * credited for the corresponding work on those ports. The original
+ * interrupt handling routines for the i386 port were written by
+ * Daniel Engström
+ */
+
+#include <common.h>
+#include <asm/interrupt.h>
+
+struct irq_action {
+	interrupt_handler_t *handler;
+	void *arg;
+	unsigned int count;
+};
+
+static struct irq_action irq_handlers[CONFIG_SYS_NUM_IRQS] = { {0} };
+static int spurious_irq_cnt = 0;
+static int spurious_irq = 0;
+
+void irq_install_handler(int irq, interrupt_handler_t *handler, void *arg)
+{
+	int status;
+
+	if (irq < 0 || irq >= CONFIG_SYS_NUM_IRQS) {
+		printf("irq_install_handler: bad irq number %d\n", irq);
+		return;
+	}
+
+	if (irq_handlers[irq].handler != NULL)
+		printf("irq_install_handler: 0x%08lx replacing 0x%08lx\n",
+		       (ulong) handler,
+		       (ulong) irq_handlers[irq].handler);
+
+	status = disable_interrupts ();
+
+	irq_handlers[irq].handler = handler;
+	irq_handlers[irq].arg = arg;
+	irq_handlers[irq].count = 0;
+
+	unmask_irq(irq);
+
+	if (status)
+		enable_interrupts();
+
+	return;
+}
+
+void irq_free_handler(int irq)
+{
+	int status;
+
+	if (irq < 0 || irq >= CONFIG_SYS_NUM_IRQS) {
+		printf("irq_free_handler: bad irq number %d\n", irq);
+		return;
+	}
+
+	status = disable_interrupts ();
+
+	mask_irq(irq);
+
+	irq_handlers[irq].handler = NULL;
+	irq_handlers[irq].arg = NULL;
+
+	if (status)
+		enable_interrupts();
+
+	return;
+}
+
+__isr__ do_irq(int irq)
+{
+	if (irq < 0 || irq >= CONFIG_SYS_NUM_IRQS) {
+		printf("do_irq: bad irq number %d\n", irq);
+		return;
+	}
+
+	if (irq_handlers[irq].handler) {
+		mask_irq(irq);
+
+		irq_handlers[irq].handler(irq_handlers[irq].arg);
+		irq_handlers[irq].count++;
+
+		unmask_irq(irq);
+		specific_eoi(irq);
+
+	} else {
+		if ((irq & 7) != 7) {
+			spurious_irq_cnt++;
+			spurious_irq = irq;
+		}
+	}
+}
+
+#if defined(CONFIG_CMD_IRQ)
+int do_irqinfo(cmd_tbl_t *cmdtp, int flag, int argc, char *argv[])
+{
+	int irq;
+
+	printf("Spurious IRQ: %u, last unknown IRQ: %d\n",
+	       spurious_irq_cnt, spurious_irq);
+
+	printf ("Interrupt-Information:\n");
+	printf ("Nr  Routine   Arg       Count\n");
+
+	for (irq = 0; irq <= CONFIG_SYS_NUM_IRQS; irq++) {
+		if (irq_handlers[irq].handler != NULL) {
+			printf ("%02d  %08lx  %08lx  %d\n",
+					irq,
+					(ulong)irq_handlers[irq].handler,
+					(ulong)irq_handlers[irq].arg,
+					irq_handlers[irq].count);
+		}
+	}
+
+	return 0;
+}
+#endif
diff --git a/lib_i386/pcat_interrupts.c b/lib_i386/pcat_interrupts.c
new file mode 100644
index 0000000..f01298e
--- /dev/null
+++ b/lib_i386/pcat_interrupts.c
@@ -0,0 +1,165 @@
+/*
+ * (C) Copyright 2009
+ * Graeme Russ, graeme.russ@gmail.com
+ *
+ * (C) Copyright 2002
+ * Daniel Engström, Omicron Ceti AB, daniel@omicron.se.
+ *
+ * See file CREDITS for list of people who contributed to this
+ * project.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License as
+ * published by the Free Software Foundation; either version 2 of
+ * the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place, Suite 330, Boston,
+ * MA 02111-1307 USA
+ */
+
+/*
+ * This file provides the interrupt handling functionality for systems
+ * based on the standard PC/AT architecture using two cascaded i8259
+ * Programmable Interrupt Controllers.
+ */
+
+#include <common.h>
+#include <asm/io.h>
+#include <asm/i8259.h>
+#include <asm/ibmpc.h>
+#include <asm/interrupt.h>
+
+#if CONFIG_SYS_NUM_IRQS != 16
+#error "CONFIG_SYS_NUM_IRQS must equal 16 if CONFIG_SYS_NUM_IRQS is defined"
+#endif
+
+DECLARE_INTERRUPT(0);
+DECLARE_INTERRUPT(1);
+DECLARE_INTERRUPT(3);
+DECLARE_INTERRUPT(4);
+DECLARE_INTERRUPT(5);
+DECLARE_INTERRUPT(6);
+DECLARE_INTERRUPT(7);
+DECLARE_INTERRUPT(8);
+DECLARE_INTERRUPT(9);
+DECLARE_INTERRUPT(10);
+DECLARE_INTERRUPT(11);
+DECLARE_INTERRUPT(12);
+DECLARE_INTERRUPT(13);
+DECLARE_INTERRUPT(14);
+DECLARE_INTERRUPT(15);
+
+int interrupt_init(void)
+{
+	u8 i;
+
+	disable_interrupts();
+
+	/* Setup interrupts */
+	set_vector(0x20, irq_0);
+	set_vector(0x21, irq_1);
+	set_vector(0x23, irq_3);
+	set_vector(0x24, irq_4);
+	set_vector(0x25, irq_5);
+	set_vector(0x26, irq_6);
+	set_vector(0x27, irq_7);
+	set_vector(0x28, irq_8);
+	set_vector(0x29, irq_9);
+	set_vector(0x2a, irq_10);
+	set_vector(0x2b, irq_11);
+	set_vector(0x2c, irq_12);
+	set_vector(0x2d, irq_13);
+	set_vector(0x2e, irq_14);
+	set_vector(0x2f, irq_15);
+
+	/* Mask all interrupts */
+	outb(0xff, MASTER_PIC + IMR);
+	outb(0xff, SLAVE_PIC + IMR);
+
+	/* Master PIC */
+	/* Place master PIC interrupts at INT20 */
+	/* ICW3, One slave PIC is present */
+	outb(ICW1_SEL|ICW1_EICW4, MASTER_PIC + ICW1);
+	outb(0x20, MASTER_PIC + ICW2);
+	outb(IR2, MASTER_PIC + ICW3);
+	outb(ICW4_PM, MASTER_PIC + ICW4);
+
+	for (i = 0; i < 8; i++)
+		outb(OCW2_SEOI | i, MASTER_PIC + OCW2);
+
+	/* Slave PIC */
+	/* Place slave PIC interrupts at INT28 */
+	/* Slave ID */
+	outb(ICW1_SEL|ICW1_EICW4, SLAVE_PIC + ICW1);
+	outb(0x28, SLAVE_PIC + ICW2);
+	outb(0x02, SLAVE_PIC + ICW3);
+	outb(ICW4_PM, SLAVE_PIC + ICW4);
+
+	for (i = 0; i < 8; i++)
+		outb(OCW2_SEOI | i, SLAVE_PIC + OCW2);
+
+	/*
+	 * Enable cascaded interrupts by unmasking the cascade IRQ pin of
+	 * the master PIC
+	 */
+	unmask_irq (2);
+
+	enable_interrupts();
+
+	return 0;
+}
+
+void mask_irq(int irq)
+{
+	int imr_port;
+
+	if (irq >= CONFIG_SYS_NUM_IRQS)
+		return;
+
+	if (irq > 7)
+		imr_port = SLAVE_PIC + IMR;
+	else
+		imr_port = MASTER_PIC + IMR;
+
+	outb(inb(imr_port) | (1 << (irq & 7)), imr_port);
+}
+
+void unmask_irq(int irq)
+{
+	int imr_port;
+
+	if (irq >= CONFIG_SYS_NUM_IRQS)
+		return;
+
+	if (irq > 7)
+		imr_port = SLAVE_PIC + IMR;
+	else
+		imr_port = MASTER_PIC + IMR;
+
+	outb(inb(imr_port) & ~(1 << (irq & 7)), imr_port);
+}
+
+void specific_eoi(int irq)
+{
+	if (irq >= CONFIG_SYS_NUM_IRQS)
+		return;
+
+	if (irq > 7) {
+		/*
+		 *  IRQ is on the slave - Issue a corresponding EOI to the
+		 *  slave PIC and an EOI for IRQ2 (the cascade interrupt)
+		 *  on the master PIC
+		 */
+		outb(OCW2_SEOI | (irq & 7), SLAVE_PIC + OCW2);
+		irq = SEOI_IR2;
+	}
+
+	outb(OCW2_SEOI | irq, MASTER_PIC + OCW2);
+}