168 lines
4.1 KiB
C
168 lines
4.1 KiB
C
/*
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* bottomhalf.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 an LED and another to turn it off
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*/
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#include <linux/delay.h>
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#include <linux/gpio.h>
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#include <linux/interrupt.h>
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#include <linux/kernel.h>
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#include <linux/module.h>
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/* Macro DECLARE_TASKLET_OLD exists for compatibiity.
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* See https://lwn.net/Articles/830964/
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*/
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#ifndef DECLARE_TASKLET_OLD
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#define DECLARE_TASKLET_OLD(arg1, arg2) DECLARE_TASKLET(arg1, arg2, 0L)
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#endif
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static int button_irqs[] = { -1, -1 };
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/* Define GPIOs for LEDs.
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* TODO: 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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* TODO: 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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/* Tasklet containing some non-trivial amount of processing */
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static void bottomhalf_tasklet_fn(unsigned long data)
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{
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pr_info("Bottom half tasklet starts\n");
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/* do something which takes a while */
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mdelay(500);
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pr_info("Bottom half tasklet ends\n");
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}
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static DECLARE_TASKLET_OLD(buttontask, bottomhalf_tasklet_fn);
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/* interrupt function triggered when a button is pressed */
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static irqreturn_t button_isr(int irq, void *data)
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{
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/* Do something quickly right now */
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if (irq == button_irqs[0] && !gpio_get_value(leds[0].gpio))
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gpio_set_value(leds[0].gpio, 1);
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else if (irq == button_irqs[1] && gpio_get_value(leds[0].gpio))
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gpio_set_value(leds[0].gpio, 0);
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/* Do the rest at leisure via the scheduler */
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tasklet_schedule(&buttontask);
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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_irq(button_irqs[0], button_isr,
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IRQF_TRIGGER_RISING | IRQF_TRIGGER_FALLING,
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"gpiomod#button1", NULL);
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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_irq(button_irqs[1], button_isr,
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IRQF_TRIGGER_RISING | IRQF_TRIGGER_FALLING,
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"gpiomod#button2", NULL);
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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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