/* * intrpt.c – An interrupt handler. * * Copyright (C) 2001 by Peter Jay Salzman */ /* * The necessary header files */ /* * Standard in kernel modules */ #include <linux/kernel.h> /* We’re doing kernel work */ #include <linux/module.h> /* Specifically, a module */ #include <linux/sched.h> #include <linux/workqueue.h> #include <linux/interrupt.h> /* We want an interrupt */ #include <asm/io.h> #define MY_WORK_QUEUE_NAME "WQsched.c" static struct workqueue_struct *my_workqueue; /* * This will get called by the kernel as soon as it’s safe * to do everything normally allowed by kernel modules. */ static void got_char(void *scancode) { printk("Scan Code %x %s./n", (int)*((char *)scancode) & 0x7F, *((char *)scancode) & 0x80 ? "Released" : "Pressed"); } /* * This function services keyboard interrupts. It reads the relevant * information from the keyboard and then puts the non time critical * part into the work queue. This will be run when the kernel considers it safe. */ irqreturn_t irq_handler(int irq, void *dev_id, struct pt_regs *regs) { /* * This variables are static because they need to be * accessible (through pointers) to the bottom half routine. */ static int initialised = 0; static unsigned char scancode; static struct work_struct task; unsigned char status; /* * Read keyboard status */ status = inb(0x64); scancode = inb(0x60); if (initialised == 0) { INIT_WORK(&task, got_char, &scancode); initialised = 1; } else { PREPARE_WORK(&task, got_char, &scancode); } queue_work(my_workqueue, &task); return IRQ_HANDLED; } /* * Initialize the module – register the IRQ handler */ int init_module() { my_workqueue = create_workqueue(MY_WORK_QUEUE_NAME); /* * Since the keyboard handler won’t co-exist with another handler, * such as us, we have to disable it (free its IRQ) before we do * anything. Since we don’t know where it is, there’s no way to * reinstate it later – so the computer will have to be rebooted * when we’re done. */ free_irq(1, NULL); /* * Request IRQ 1, the keyboard IRQ, to go to our irq_handler. * SA_SHIRQ means we’re willing to have othe handlers on this IRQ. * SA_INTERRUPT can be used to make the handler into a fast interrupt. */ return request_irq(1, /* The number of the keyboard IRQ on PCs */ irq_handler, /* our handler */ SA_SHIRQ, "test_keyboard_irq_handler", (void *)(irq_handler)); } /* * Cleanup */ void cleanup_module() { /* * This is only here for completeness. It’s totally irrelevant, since * we don’t have a way to restore the normal keyboard interrupt so the * computer is completely useless and has to be rebooted. */ free_irq(1, NULL); } /* * some work_queue related functions are just available to GPL licensed Modules */ MODULE_LICENSE("GPL");
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