mirror of
https://github.com/sysprog21/lkmpg.git
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152 lines
3.7 KiB
C
152 lines
3.7 KiB
C
/*
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* bh_thread.c - Top and bottom half interrupt handling
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*
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* Based upon the RPi example by Stefan Wendler (devnull@kaltpost.de)
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* from:
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* https://github.com/wendlers/rpi-kmod-samples
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*
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* Press one button to turn on a LED and another to turn it off
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*/
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#include <linux/module.h>
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#include <linux/kernel.h>
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#include <linux/gpio.h>
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#include <linux/delay.h>
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#include <linux/interrupt.h>
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static int button_irqs[] = { -1, -1 };
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/* Define GPIOs for LEDs.
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* FIXME: Change the numbers for the GPIO on your board.
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*/
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static struct gpio leds[] = { { 4, GPIOF_OUT_INIT_LOW, "LED 1" } };
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/* Define GPIOs for BUTTONS
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* FIXME: Change the numbers for the GPIO on your board.
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*/
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static struct gpio buttons[] = {
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{ 17, GPIOF_IN, "LED 1 ON BUTTON" },
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{ 18, GPIOF_IN, "LED 1 OFF BUTTON" },
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};
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/* This happens immediately, when the IRQ is triggered */
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static irqreturn_t button_top_half(int irq, void *ident)
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{
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return IRQ_WAKE_THREAD;
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}
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/* This can happen at leisure, freeing up IRQs for other high priority task */
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static irqreturn_t button_bottom_half(int irq, void *ident)
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{
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pr_info("Bottom half task starts\n");
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mdelay(500); /* do something which takes a while */
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pr_info("Bottom half task ends\n");
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return IRQ_HANDLED;
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}
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static int __init bottomhalf_init(void)
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{
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int ret = 0;
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pr_info("%s\n", __func__);
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/* register LED gpios */
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ret = gpio_request_array(leds, ARRAY_SIZE(leds));
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if (ret) {
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pr_err("Unable to request GPIOs for LEDs: %d\n", ret);
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return ret;
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}
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/* register BUTTON gpios */
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ret = gpio_request_array(buttons, ARRAY_SIZE(buttons));
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if (ret) {
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pr_err("Unable to request GPIOs for BUTTONs: %d\n", ret);
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goto fail1;
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}
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pr_info("Current button1 value: %d\n", gpio_get_value(buttons[0].gpio));
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ret = gpio_to_irq(buttons[0].gpio);
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if (ret < 0) {
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pr_err("Unable to request IRQ: %d\n", ret);
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goto fail2;
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}
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button_irqs[0] = ret;
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pr_info("Successfully requested BUTTON1 IRQ # %d\n", button_irqs[0]);
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ret = request_threaded_irq(button_irqs[0], button_top_half,
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button_bottom_half,
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IRQF_TRIGGER_RISING | IRQF_TRIGGER_FALLING,
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"gpiomod#button1", &buttons[0]);
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if (ret) {
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pr_err("Unable to request IRQ: %d\n", ret);
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goto fail2;
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}
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ret = gpio_to_irq(buttons[1].gpio);
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if (ret < 0) {
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pr_err("Unable to request IRQ: %d\n", ret);
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goto fail2;
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}
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button_irqs[1] = ret;
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pr_info("Successfully requested BUTTON2 IRQ # %d\n", button_irqs[1]);
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ret = request_threaded_irq(button_irqs[1], button_top_half,
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button_bottom_half,
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IRQF_TRIGGER_RISING | IRQF_TRIGGER_FALLING,
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"gpiomod#button2", &buttons[1]);
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if (ret) {
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pr_err("Unable to request IRQ: %d\n", ret);
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goto fail3;
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}
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return 0;
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/* cleanup what has been setup so far */
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fail3:
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free_irq(button_irqs[0], NULL);
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fail2:
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gpio_free_array(buttons, ARRAY_SIZE(leds));
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fail1:
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gpio_free_array(leds, ARRAY_SIZE(leds));
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return ret;
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}
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static void __exit bottomhalf_exit(void)
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{
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int i;
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pr_info("%s\n", __func__);
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/* free irqs */
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free_irq(button_irqs[0], NULL);
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free_irq(button_irqs[1], NULL);
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/* turn all LEDs off */
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for (i = 0; i < ARRAY_SIZE(leds); i++)
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gpio_set_value(leds[i].gpio, 0);
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/* unregister */
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gpio_free_array(leds, ARRAY_SIZE(leds));
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gpio_free_array(buttons, ARRAY_SIZE(buttons));
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}
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module_init(bottomhalf_init);
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module_exit(bottomhalf_exit);
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MODULE_LICENSE("GPL");
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MODULE_DESCRIPTION("Interrupt with top and bottom half");
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