projects / linux.git / blame
| Commit | Line | Data |
|---|---|---|
| 1da177e4 LT |
1 | /* |
| 2 | * include/asm-mips/i8259.h | |
| 3 | * | |
| 4 | * i8259A interrupt definitions. | |
| 5 | * | |
| 6 | * Copyright (C) 2003 Maciej W. Rozycki | |
| 7 | * Copyright (C) 2003 Ralf Baechle <[email protected]> | |
| 8 | * | |
| 9 | * This program is free software; you can redistribute it and/or | |
| 10 | * modify it under the terms of the GNU General Public License | |
| 11 | * as published by the Free Software Foundation; either version | |
| 12 | * 2 of the License, or (at your option) any later version. | |
| 13 | */ | |
| 14 | #ifndef _ASM_I8259_H | |
| 15 | #define _ASM_I8259_H | |
| 16 | ||
| 17 | #include <linux/compiler.h> | |
| 18 | #include <linux/spinlock.h> | |
| 19 | ||
| 20 | #include <asm/io.h> | |
| 21 | ||
| 22 | extern spinlock_t i8259A_lock; | |
| 23 | ||
| 24 | extern void init_i8259_irqs(void); | |
| 25 | ||
| 26 | /* | |
| 27 | * Do the traditional i8259 interrupt polling thing. This is for the few | |
| 28 | * cases where no better interrupt acknowledge method is available and we | |
| 29 | * absolutely must touch the i8259. | |
| 30 | */ | |
| 31 | static inline int i8259_irq(void) | |
| 32 | { | |
| 33 | int irq; | |
| 34 | ||
| 35 | spin_lock(&i8259A_lock); | |
| 36 | ||
| 37 | /* Perform an interrupt acknowledge cycle on controller 1. */ | |
| 38 | outb(0x0C, 0x20); /* prepare for poll */ | |
| 39 | irq = inb(0x20) & 7; | |
| 40 | if (irq == 2) { | |
| 41 | /* | |
| 42 | * Interrupt is cascaded so perform interrupt | |
| 43 | * acknowledge on controller 2. | |
| 44 | */ | |
| 45 | outb(0x0C, 0xA0); /* prepare for poll */ | |
| 46 | irq = (inb(0xA0) & 7) + 8; | |
| 47 | } | |
| 48 | ||
| 49 | if (unlikely(irq == 7)) { | |
| 50 | /* | |
| 51 | * This may be a spurious interrupt. | |
| 52 | * | |
| 53 | * Read the interrupt status register (ISR). If the most | |
| 54 | * significant bit is not set then there is no valid | |
| 55 | * interrupt. | |
| 56 | */ | |
| 57 | outb(0x0B, 0x20); /* ISR register */ | |
| 58 | if(~inb(0x20) & 0x80) | |
| 59 | irq = -1; | |
| 60 | } | |
| 61 | ||
| 62 | spin_unlock(&i8259A_lock); | |
| 63 | ||
| 64 | return irq; | |
| 65 | } | |
| 66 | ||
| 67 | #endif /* _ASM_I8259_H */ |