c - 如何在一个内核模块中包含三个 IRQ 处理程序？

Question

我目前正在学习 Derek Molloy 在他的书“Exploring Raspberry Pi - Interfacing to The Real World with Embedded Linux”一书中的示例。我使用了 list 16-3 中的示例，不幸的是我无法在网上找到它。

该示例包含用于单个中断的内核模块代码。它从 GPIO 17 的按钮读取信号，然后发送中断以打开 GPIO 27 的 LED。本书使用默认的 GPIO 引脚编号，所以我也这样做。

我想做的是修改代码以包含另外 2 个按钮-LED 对。我想这样做:

• GPIO 17 打开/关闭 GPIO 23
• GPIO 27 打开/关闭 GPIO 24
• GPIO 22 打开/关闭 GPIO 25

这是我使用的修改后的代码。

static unsigned int gpioDevice1 = 17;
static unsigned int gpioDevice2 = 27;
static unsigned int gpioDevice3 = 22;
static unsigned int gpioButton1 = 24; 
static unsigned int gpioButton2 = 23;
static unsigned int gpioButton3 = 25;
static unsigned int irqNumber1On; 
static unsigned int irqNumber2On; 
static unsigned int irqNumber3On;
static unsigned int buttonCounter1 = 0; 
static unsigned int buttonCounter2 = 0; 
static unsigned int buttonCounter3 = 0; 
static unsigned int totalCounter = 0; 
static bool devOn1 = 0; // Initial state of devices
static bool devOn2 = 0;
static bool devOn3 = 0;

// prototype for the custom IRQ handler function, function below. Should I use IRQF_SHARED here?

static irq_handler_t rpi3_gpio_irq_handler_1(unsigned int irq, void *dev_id, struct pt_regs *regs); 
static irq_handler_t rpi3_gpio_irq_handler_2(unsigned int irq, void *dev_id, struct pt_regs *regs); 
static irq_handler_t rpi3_gpio_irq_handler_3(unsigned int irq, void *dev_id, struct pt_regs *regs);

/** LKM initialization function */

static int __init rpi3_gpio_init(void) {
    int result1On = 0;
    int result2On = 0;
    int result3On = 0;
    printk(KERN_INFO "GPIO_TEST: Initializing the GPIO_TEST LKM\n");

    /* GPIO validation on the three devices */
    if (!gpio_is_valid(gpioDevice1) || !gpio_is_valid(gpioDevice2) || !gpio_is_valid(gpioDevice3)) {
        printk(KERN_INFO "GPIO_TEST: invalid GPIO for Devices\n");
        return -ENODEV; //wouldn't using ENXIO is more appropriate than ENODEV?
    }

    /* Configuring GPIO pins for the pairs */
    gpio_request(gpioDevice1, "sysfs"); // request LED GPIO
    gpio_direction_output(gpioDevice1, devOn1); // set in output mode
    gpio_export(gpioDevice1, false); // appears in /sys/class/gpio
    // false prevents in/out change

    gpio_request(gpioDevice2, "sysfs");
    gpio_direction_output(gpioDevice2, devOn2);
    gpio_export(gpioDevice2, false); 

    gpio_request(gpioDevice3, "sysfs"); 
    gpio_direction_output(gpioDevice3, devOn3); 
    gpio_export(gpioDevice3, false); 

    gpio_request(gpioButton1, "sysfs"); // set up gpioButton1
    gpio_direction_input(gpioButton1); // set up as input
    gpio_set_debounce(gpioButton1, 200); // debounce delay of 200ms to avoid erratic and uncontrolled interrupt
    gpio_export(gpioButton1, false); // appears in /sys/class/gpio

    gpio_request(gpioButton2, "sysfs");
    gpio_direction_input(gpioButton2);
    gpio_set_debounce(gpioButton2, 200);
    gpio_export(gpioButton2, false);

    gpio_request(gpioButton3, "sysfs");
    gpio_direction_input(gpioButton3);
    gpio_set_debounce(gpioButton3, 200);
    gpio_export(gpioButton3, false);

    printk(KERN_INFO "GPIO_TEST: button1 value is currently: %d\n", gpio_get_value(gpioButton1));
    irqNumber1On = gpio_to_irq(gpioButton1); // map GPIO to IRQ number 189?
    printk(KERN_INFO "GPIO_TEST: button1 mapped to IRQ: %d\n", irqNumber1On);

    printk(KERN_INFO "GPIO_TEST: button2 value is currently: %d\n", gpio_get_value(gpioButton2));
    irqNumber2On = gpio_to_irq(gpioButton2); // map GPIO to IRQ number 190?
    printk(KERN_INFO "GPIO_TEST: button2 mapped to IRQ: %d\n", irqNumber2On);

    printk(KERN_INFO "GPIO_TEST: button3 value is currently: %d\n", gpio_get_value(gpioButton3));
    irqNumber3On = gpio_to_irq(gpioButton3); // map GPIO to IRQ number 191?
    printk(KERN_INFO "GPIO_TEST: button3 mapped to IRQ: %d\n", irqNumber3On);

    /* Interrupt lines when tactile button is pressed */
    result1On = request_irq(irqNumber1On, // interrupt number requested
            (irq_handler_t) rpi3_gpio_irq_handler_1, // handler function
            // TO DO: Insert IRQF_SHARED here?
            IRQF_TRIGGER_RISING, // on rising edge (press, not release)
            "rpi3_gpio_handler", // used in /proc/interrupts
            NULL); // *dev_id for shared interrupt lines shouldn't be NULL
    printk(KERN_INFO "GPIO_TEST: IRQ request result for device 1 is: %d\n", result1On);
    return result1On;

    result2On = request_irq(irqNumber2On,
            (irq_handler_t) rpi3_gpio_irq_handler_2,
            IRQF_TRIGGER_RISING,
            "rpi3_gpio_handler",
            NULL); 
    printk(KERN_INFO "GPIO_TEST: IRQ request result for device 2 is: %d\n", result2On);
    return result2On;

    result3On = request_irq(irqNumber3On,
            (irq_handler_t) rpi3_gpio_irq_handler_3,
            IRQF_TRIGGER_RISING,
            "rpi3_gpio_handler",
            NULL); 
    printk(KERN_INFO "GPIO_TEST: IRQ request result for device 3 is: %d\n", result3On);
    return result3On;
}

static void __exit rpi3_gpio_exit(void) {

    printk(KERN_INFO "GPIO_TEST: button 1 value is currently: %d\n", gpio_get_value(gpioButton1));
    printk(KERN_INFO "GPIO_TEST: button 1 was pressed %d times\n", buttonCounter1);
    printk(KERN_INFO "GPIO_TEST: button 2 value is currently: %d\n", gpio_get_value(gpioButton2));
    printk(KERN_INFO "GPIO_TEST: button 2 was pressed %d times\n", buttonCounter2);
    printk(KERN_INFO "GPIO_TEST: button 3 value is currently: %d\n", gpio_get_value(gpioButton3));
    printk(KERN_INFO "GPIO_TEST: button 3 was pressed %d times\n", buttonCounter3);
    printk(KERN_INFO "GPIO_TEST: in total the buttons was pressed %d times\n", totalCounter);

    gpio_set_value(gpioDevice1, 0); // turn the LED off
    gpio_unexport(gpioDevice1); // unexport the LED GPIO
    free_irq(irqNumber1On, NULL); // free the IRQ number, no *dev_id?
    gpio_unexport(gpioButton1); // unexport the Button GPIO
    gpio_free(gpioDevice1); // free the LED GPIO
    gpio_free(gpioButton1); // free the Button GPIO

    gpio_set_value(gpioDevice2, 0);
    gpio_unexport(gpioDevice2);
    free_irq(irqNumber2On, NULL);
    gpio_unexport(gpioButton2);
    gpio_free(gpioDevice2);
    gpio_free(gpioButton2);

    gpio_set_value(gpioDevice3, 0);
    gpio_unexport(gpioDevice3);
    free_irq(irqNumber3On, NULL);
    gpio_unexport(gpioButton3);
    gpio_free(gpioDevice3);
    gpio_free(gpioButton3);

    printk(KERN_INFO "GPIO_TEST: Goodbye from the LKM!\n");
}

/** GPIO IRQ Handler functions */

static irq_handler_t rpi3_gpio_irq_handler_1(unsigned int irq, void *dev_id, struct pt_regs *regs) {
    devOn1 = !devOn1; // invert the LED state
    gpio_set_value(gpioDevice1, devOn1); // set LED accordingly
    printk(KERN_INFO "GPIO_TEST: Interrupt! (button 1 is %d)\n",
    gpio_get_value(gpioButton1));
    buttonCounter1++;
    totalCounter++; // global counter
    return (irq_handler_t) IRQ_HANDLED; // announce IRQ handled
}

static irq_handler_t rpi3_gpio_irq_handler_2(unsigned int irq, void *dev_id, struct pt_regs *regs) {
    devOn2 = !devOn2;
    gpio_set_value(gpioDevice2, devOn2);
    printk(KERN_INFO "GPIO_TEST: Interrupt! (button 2 is %d)\n",
    gpio_get_value(gpioButton2));
    buttonCounter2++;
    totalCounter++; 
    return (irq_handler_t) IRQ_HANDLED;
}

static irq_handler_t rpi3_gpio_irq_handler_3(unsigned int irq, void *dev_id, struct pt_regs *regs) {
    devOn3 = !devOn3;
    gpio_set_value(gpioDevice3, devOn3);
    printk(KERN_INFO "GPIO_TEST: Interrupt! (button 3 is %d)\n",
    gpio_get_value(gpioButton3));
    buttonCounter3++;
    totalCounter++; 
    return (irq_handler_t) IRQ_HANDLED;
}

module_init(rpi3_gpio_init);
module_exit(rpi3_gpio_exit);

为了获取 IRQ 编号，我使用 gpio_to_irq() 就像在示例中一样，因为我不知道哪些值是有效数字。

第一对效果很好，但无论我按多少次按钮，其他对都不起作用。当我使用 cat/proc/interrupts 检查 IRQ 编号时

似乎只有第一个获得IRQ号，即189。假设，另外两个应该可能得到 190 和 191，但他们不在那里。

printk() 函数也只显示 irqnumber1On 行，而 irqnumber2On 和 irqnumber3On 行> 没有出现。

我给中断设置了 NULL dev_id，因为我不知道如何为按钮提供/读取 ID。我尝试了随机数组合，例如 500、505 和 550 但终端显示 warning: passing argument 5 of 'request_irq' makes来自没有转换的整数的指针。

那么，我在这里做错了什么？我坚持了很长一段时间。我应该尝试使用 IRQF_SHARED 吗？但每个中断(或本例中的按钮)都需要特定的 dev_id。我的新手认为这样做是不可能的。

PS:我知道代码看起来乱糟糟的，但请多多包涵。

PPS:如果认为有必要，我可以删除部分代码。

Answer 1

此语句之后的任何代码:

return result1On; 

永远不会被执行。

这意味着其他两个按钮中断永远不会被处理