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Diffstat (limited to 'include/asm-mips/i8259.h')
| -rw-r--r-- | include/asm-mips/i8259.h | 67 |
1 files changed, 67 insertions, 0 deletions
diff --git a/include/asm-mips/i8259.h b/include/asm-mips/i8259.h new file mode 100644 index 000000000000..0214abe3f0af --- /dev/null +++ b/include/asm-mips/i8259.h @@ -0,0 +1,67 @@ +/* + * 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 */ |