| 1 | // SPDX-License-Identifier: GPL-2.0-only |
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| 2 | /* |
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| 3 | * Dummy IRQ handler driver. |
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| 4 | * |
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| 5 | * This module only registers itself as a handler that is specified to it |
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| 6 | * by the 'irq' parameter. |
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| 7 | * |
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| 8 | * The sole purpose of this module is to help with debugging of systems on |
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| 9 | * which spurious IRQs would happen on disabled IRQ vector. |
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| 10 | * |
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| 11 | * Copyright (C) 2013 Jiri Kosina |
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| 12 | */ |
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| 13 | |
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| 14 | #include <linux/module.h> |
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| 15 | #include <linux/irq.h> |
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| 16 | #include <linux/interrupt.h> |
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| 17 | |
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| 18 | static int irq = -1; |
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| 19 | |
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| 20 | static irqreturn_t dummy_interrupt(int irq, void *dev_id) |
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| 21 | { |
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| 22 | static int count = 0; |
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| 23 | |
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| 24 | if (count == 0) { |
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| 25 | printk(KERN_INFO "dummy-irq: interrupt occurred on IRQ %d\n" , |
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| 26 | irq); |
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| 27 | count++; |
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| 28 | } |
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| 29 | |
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| 30 | return IRQ_NONE; |
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| 31 | } |
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| 32 | |
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| 33 | static int __init dummy_irq_init(void) |
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| 34 | { |
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| 35 | if (irq < 0) { |
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| 36 | printk(KERN_ERR "dummy-irq: no IRQ given. Use irq=N\n" ); |
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| 37 | return -EIO; |
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| 38 | } |
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| 39 | if (request_irq(irq, handler: &dummy_interrupt, IRQF_SHARED, name: "dummy_irq" , dev: &irq)) { |
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| 40 | printk(KERN_ERR "dummy-irq: cannot register IRQ %d\n" , irq); |
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| 41 | return -EIO; |
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| 42 | } |
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| 43 | printk(KERN_INFO "dummy-irq: registered for IRQ %d\n" , irq); |
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| 44 | return 0; |
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| 45 | } |
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| 46 | |
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| 47 | static void __exit dummy_irq_exit(void) |
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| 48 | { |
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| 49 | printk(KERN_INFO "dummy-irq unloaded\n" ); |
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| 50 | free_irq(irq, &irq); |
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| 51 | } |
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| 52 | |
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| 53 | module_init(dummy_irq_init); |
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| 54 | module_exit(dummy_irq_exit); |
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| 55 | |
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| 56 | MODULE_LICENSE("GPL" ); |
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| 57 | MODULE_AUTHOR("Jiri Kosina" ); |
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| 58 | module_param_hw(irq, uint, irq, 0444); |
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| 59 | MODULE_PARM_DESC(irq, "The IRQ to register for" ); |
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| 60 | MODULE_DESCRIPTION("Dummy IRQ handler driver" ); |
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| 61 | |
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