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Handling Interrupts in a Device Driver

I wrote a simple character driver and requested an IRQ on the gpio pin and asked for a handler for it.

err = request_irq (irq, irq_handler, IRQF_SHARED | IRQF_TRIGGER_RISING, INTERRUPT_DEVICE_NAME, raspi_gpio_devp);

static irqreturn_t irq_handler (int irq, void * arg);

Now, from theory, I know that after an interrupt, the Interrupt Controller inform the processor about the call to do_IRQ (), which will check the IDT and call my interrupt handler for this line.

how does the kernel know that the interrupt handler was for this particular device file

I also know that interrupt handlers do not start in any process context. But let me say that I refer to any variable declared outside the processing area of ​​the handler, static global flag = 0. In the handler, I make flag = 1, indicating that an interrupt has occurred. This variable is in the context of the process. Therefore, I am confused by the way this handler does not in any context of the process change the variable in the context of the process.

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The kernel does not know that this particular interrupt is for a specific device.

, , , irq_handler raspi_gpio_devp . (: irq_handler(irq, raspi_gpio_devp)).

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int irq_handler(int irq, void* dev_id) {
    struct raspi_gpio_dev *raspi_gpio_devp = (struct raspi_gpio_dev *) dev_id;
    if (!my_gpio_irq_occured(raspi_gpio_devp))
        return IRQ_NONE;
    /* do stuff here */
    return IRQ_HANDLED;
}

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