| Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 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 <ralf@linux-mips.org> |
| 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 */ |