/* * 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 */