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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 /include/asm-mips/i8259.h
downloadop-kernel-dev-1da177e4c3f41524e886b7f1b8a0c1fc7321cac2.zip
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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!
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diff --git a/include/asm-mips/i8259.h b/include/asm-mips/i8259.h
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+/*
+ * include/asm-mips/i8259.h
+ *
+ * i8259A interrupt definitions.
+ *
+ * Copyright (C) 2003 Maciej W. Rozycki
+ * Copyright (C) 2003 Ralf Baechle <ralf@linux-mips.org>
+ *
+ * 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.
+ */
+#ifndef _ASM_I8259_H
+#define _ASM_I8259_H
+
+#include <linux/compiler.h>
+#include <linux/spinlock.h>
+
+#include <asm/io.h>
+
+extern spinlock_t i8259A_lock;
+
+extern void init_i8259_irqs(void);
+
+/*
+ * Do the traditional i8259 interrupt polling thing. This is for the few
+ * cases where no better interrupt acknowledge method is available and we
+ * absolutely must touch the i8259.
+ */
+static inline int i8259_irq(void)
+{
+ int irq;
+
+ spin_lock(&i8259A_lock);
+
+ /* Perform an interrupt acknowledge cycle on controller 1. */
+ outb(0x0C, 0x20); /* prepare for poll */
+ irq = inb(0x20) & 7;
+ if (irq == 2) {
+ /*
+ * Interrupt is cascaded so perform interrupt
+ * acknowledge on controller 2.
+ */
+ outb(0x0C, 0xA0); /* prepare for poll */
+ irq = (inb(0xA0) & 7) + 8;
+ }
+
+ if (unlikely(irq == 7)) {
+ /*
+ * This may be a spurious interrupt.
+ *
+ * Read the interrupt status register (ISR). If the most
+ * significant bit is not set then there is no valid
+ * interrupt.
+ */
+ outb(0x0B, 0x20); /* ISR register */
+ if(~inb(0x20) & 0x80)
+ irq = -1;
+ }
+
+ spin_unlock(&i8259A_lock);
+
+ return irq;
+}
+
+#endif /* _ASM_I8259_H */
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