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Xilinx Zynq平台上的Linux 4.5 GPIO通过Devicetree中断

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我使用的是定制开发板和Zynq XC72010,用于运行Linux 4.5内核.我正在为我们正在测试的芯片开发设备驱动程序,我在尝试将GPIO线绑定到软件IRQ时遇到很多问题.到目前为止,我已经尝试了一些方法,并且耗尽了我能想到的任何谷歌搜索.我的设备配置的相关部分：

/ {
    compatible = "xlnx,zynq-7000";

    amba {
        compatible = "simple-bus";
        #address-cells = <1>;
        #size-cells = <1>;
        interrupt-parent = <&intc>;
        ranges;

        intc: interrupt-controller@f8f01000 {
            compatible = "arm,cortex-a9-gic";
            #interrupt-cells = <3>;
            interrupt-controller;
            reg = <0xF8F01000 0x1000>,
                  <0xF8F00100 0x100>;
        };

        i2c0: i2c@e0004000 {
            compatible = "cdns,i2c-r1p10";
            status = "disabled";
            clocks = <&clkc 38>;
            interrupt-parent = <&intc>;
            interrupts = <0 25 4>;
            reg = <0xe0004000 0x1000>;
            #address-cells = <1>;
            #size-cells = <0>;

            // I WANT INTERRUPT TO TRIGGER
            // ON THIS DEVICE (axi_gpio_0, pin 2)
            device: device@48 {
                compatible = "device,name";
                reg = <0x48>;
                reset-gpios = <&axi_gpio_0 1 0>;
                interrupt-parent = <&axi_gpio_0>;
                interrupt-gpios = <&axi_gpio_0 2 0>;
            };
        };
    };

    amba_pl {
        #address-cells = <1>;
        #size-cells = <1>;
        compatible = "simple-bus";
        ranges ;
        axi_gpio_0: gpio@41200000 {
            #gpio-cells = <2>;
            compatible = "xlnx,xps-gpio-1.00.a";
            gpio-controller;
            interrupt-parent = <&intc>;
            interrupts = <0 31 4>;
            reg = <0x41200000 0x10000>;
            xlnx,all-inputs = <0x0>;
            xlnx,all-inputs-2 = <0x0>;
            xlnx,all-outputs = <0x0>;
            xlnx,all-outputs-2 = <0x0>;
            xlnx,dout-default = <0x00000000>;
            xlnx,dout-default-2 = <0x00000000>;
            xlnx,gpio-width = <0x10>;
            xlnx,gpio2-width = <0x20>;
            xlnx,interrupt-present = <0x1>;
            xlnx,is-dual = <0x0>;
            xlnx,tri-default = <0xFFFFFFFF>;
            xlnx,tri-default-2 = <0xFFFFFFFF>;
    };
};

我试图在’device’内的’axi_gpio_0’的引脚2上分配一个中断.

浏览谷歌产生了3种在驱动程序代码中绑定中断的常用方法：

/* Method 1 */
device->interrupt_gpio = devm_gpiod_get_optional(&i2c_client->dev,
                                        "interrupt", GPIOD_IN);

if(IS_ERR(device->interrupt_gpio))
    return PTR_ERR(device->interrupt_gpio);

printk("device: Interrupt GPIO = %d\n",desc_to_gpio(device->interrupt_gpio));

irq = gpiod_to_irq(device->interrupt_gpio);
printk("device: IRQ = %d\n",irq);

ret = devm_request_threaded_irq(&i2c_client->dev, irq,
    NULL, device_irq_thread, IRQF_ONESHOT | IRQF_TRIGGER_HIGH,
    "device", device);
if (ret != 0)
    dev_err(&i2c_client->dev, "Failed to request IRQ: %d\n", ret);



/* Method 2 */
device->interrupt_gpio = devm_gpiod_get_optional(&i2c_client->dev,
    "interrupt", GPIOD_ASIS);

if (IS_ERR(device->interrupt_gpio))
    return PTR_ERR(device->interrupt_gpio);


if (device->interrupt_gpio) {
    dev_info(&i2c_client->dev, "Found interrupt GPIO: %d\n",desc_to_gpio(device->interrupt_gpio));
    dev_info(&i2c_client->dev, "IRQ Number: %d\n",gpiod_to_irq(device->interrupt_gpio));

    gpio_request(desc_to_gpio(device->interrupt_gpio), "DEVICE_INT");    // Request a GPIO pin from the driver
    gpio_direction_input(desc_to_gpio(device->interrupt_gpio));           // Set GPIO as input
    gpio_set_debounce(desc_to_gpio(device->interrupt_gpio), 50);          // Set a 50ms debounce, adjust to your needs
    gpio_export(desc_to_gpio(device->interrupt_gpio), false);                    // The GPIO will appear in /sys/class/gpio

    ret = request_irq(gpiod_to_irq(device->interrupt_gpio),             // requested interrupt
                   (irq_handler_t) irqHandler,  // pointer to handler function
                   IRQF_TRIGGER_RISING,         // interrupt mode flag
                   "DEVICE_IRQ_HANDLER",        // used in /proc/interrupts
                   NULL);                       // the *dev_id shared interrupt lines, NULL is okay
    if (ret != 0) {
        dev_err(&i2c_client->dev,
            "Failed to request IRQ: %d\n", ret);
    }
}
else {
    dev_err(&i2c_client->dev, "Failed to get interrupt GPIO pin\n");
}



/* Method 3 */
dev_info(&i2c_client->dev, "IRQ requested: %d\n", i2c_client->irq);

ret = devm_request_threaded_irq(&i2c_client->dev, i2c_client->irq,
NULL, device_irq_thread, IRQF_ONESHOT | IRQF_TRIGGER_LOW,
"device", device);
if (ret != 0)
    dev_err(&i2c_client->dev, "Failed to request IRQ: %d\n", ret);

我尝试了所有这些方法和各种devicetree配置的组合,但它们都没有实现我需要的功能.

方法1导致此输出：

device: Interrupt GPIO = 892
device: IRQ = -6
device 0-0048: Failed to request IRQ: -22

方法2导致此输出：

device 0-0048: Found interrupt GPIO: 892
device 0-0048: IRQ Number: -6
device 0-0048: Failed to request IRQ: -22

因此,尝试使用描述符GPIO和旧的GPIO api都不能成功绑定中断.

为了尝试方法3,我调整了devicetree：

device: device@48 {
    compatible = "device,name";
    reg = <0x48>;
    interrupt-parent = <&axi_gpio_0>; // or <&intc>?
    interrupts = <0 2 0x02>; // trying to grab pin 2
};

方法3导致此输出：

genirq: Setting trigger mode 2 for irq 168 failed (gic_set_type+0x0/0x48)
device 0-0048: IRQ requested: 168
genirq: Setting trigger mode 8 for irq 168 failed (gic_set_type+0x0/0x48)
device 0-0048: Failed to request IRQ: -22

似乎问题是将软件中断分配给Linux中的特定GPIO.我不知道我在这里缺少什么.任何建议表示赞赏.

编辑1：

我发现Linux不管出于什么原因都不喜欢低级别的中断.将方法3改为：

device: device@48 {
    compatible = "device,name";
    reg = <0x48>;
    interrupt-parent = <&axi_gpio_0>;
    interrupts = <0 2 0x04>;
};

和驱动程序代码：

dev_info(&i2c_client->dev, "IRQ requested: %d\n", i2c_client->irq);

ret = devm_request_threaded_irq(&i2c_client->dev, i2c_client->irq,
NULL, device_irq_thread, IRQF_ONESHOT | IRQF_TRIGGER_HIGH,
"device", device);
if (ret != 0)
    dev_err(&i2c_client->dev, "Failed to request IRQ: %d\n", ret);

允许我成功申请IRQ.但是,我的信号是低电平的,所以这对我没什么帮助.另外,我不确定这种方法是否将axi_gpio_0引脚2作为中断信号引用.我可以使用intc和axi_gpio_0作为interrupt-parent,它映射到相同的IRQ号(我从cat / proc / interrupts看到这个).因此,忽略信号的极性,如何根据axi_gpio_0引脚2的切换确保触发注册的中断？

编辑2：

我跟踪了向中断控制器请求驱动器的低电??平有效中断的问题：kernel / drivers / irqchip / irq-gic.c.这部分代码是导致问题的原因：

static int gic_set_type(struct irq_data *d, unsigned int type)
{
    void __iomem *base = gic_dist_base(d);
    unsigned int gicirq = gic_irq(d);

    /* Interrupt configuration for SGIs can't be changed */
    if (gicirq < 16)
        return -EINVAL;

    /* SPIs have restrictions on the supported types */
    if (gicirq >= 32 && type != IRQ_TYPE_LEVEL_HIGH &&
                type != IRQ_TYPE_EDGE_RISING)
        return -EINVAL;

    return gic_configure_irq(gicirq, type, base, NULL);
}

黑客入侵内核根本不是我想做的事情,而是评论出来：

/* SPIs have restrictions on the supported types */
/*if (gicirq >= 32 && type != IRQ_TYPE_LEVEL_HIGH &&
            type != IRQ_TYPE_EDGE_RISING)
return -EINVAL;*/

允许我请求低电平有效的中断.出于测试目的,这应该暂时起作用.

更新：

我已经在GPIO引脚上成功创建了一个IRQ.我的问题出在我使用的GPIO控制器上.控制器是Zynq可编程逻辑模块内部的Xilinx IP模块,该控制器无法触发GPIO引脚上的中断(原因我不知道).我把电路板上的中断引脚焊接到一个不同的,更通用的控制器上的GPIO引脚上,现在Linux正在和我很好地配合.

总而言之,匹配compatible =“xlnx,xps-gpio-1.00.a”的GPIO控制器;无法绑定到Linux中的软件中断.如果您遇到此问题,请使用不同的GPIO控制器.

谢谢大家的帮助.

解决方法:

使用方法3的设备树节点,您应该能够使用irq_of_parse_and_map(i2c_client-> dev.of_node,0)检索IRQ.

然后可以使用devm_request_threaded_irq()完成检索到的IRQ.

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