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0049_DTS_GPIO_Kernel_Driver_Interrupt.md

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0049_DTS_GPIO_Kernel_Driver_Interrupt.md

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DTS GPIO Interrupt

GPIO口中断分析

Check GPIO

  • /sys/kernel/debug/gpio 
    gpiochip0: GPIOs 0-53, parent: platform/fe200000.gpio, pinctrl-bcm2835:
 gpio-23  (                    |keys-int            ) in  lo IRQ
 gpio-42  (                    |led0                ) out lo

gpiochip2: GPIOs 100-101, brcmvirt-gpio, can sleep:

gpiochip1: GPIOs 504-511, parent: platform/soc:firmware:gpio, raspberrypi-exp-gpio, can sleep:
 gpio-504 (BT_ON               )
 gpio-505 (WL_ON               )
 gpio-506 (PWR_LED_OFF         |led1                ) out lo
 gpio-507 (GLOBAL_RESET        )
 gpio-508 (VDD_SD_IO_SEL       |vdd-sd-io           ) out hi
 gpio-509 (CAM_GPIO            )
 gpio-510 (                    )
 gpio-511 (                    )
  • echo 21 > /sys/class/gpio/export
  • /sys/kernel/debug/gpio 
    gpiochip0: GPIOs 0-53, parent: platform/fe200000.gpio, pinctrl-bcm2835:
 gpio-21  (                    |sysfs               ) in  lo
 gpio-23  (                    |keys-int            ) in  lo IRQ
 gpio-42  (                    |led0                ) out lo

gpiochip2: GPIOs 100-101, brcmvirt-gpio, can sleep:

gpiochip1: GPIOs 504-511, parent: platform/soc:firmware:gpio, raspberrypi-exp-gpio, can sleep:
 gpio-504 (BT_ON               )
 gpio-505 (WL_ON               )
 gpio-506 (PWR_LED_OFF         |led1                ) out lo
 gpio-507 (GLOBAL_RESET        )
 gpio-508 (VDD_SD_IO_SEL       |vdd-sd-io           ) out hi
 gpio-509 (CAM_GPIO            )
 gpio-510 (                    )
 gpio-511 (                    )

Sense HAT GPIO Interrupt

  • 如上可知gpio-23被配置为中断信号，是因为树莓派上挂在了Sense_HAT的原因：arch/arm/boot/dts/overlays/rpi-sense-overlay.dts 
    // rpi-sense HAT
/dts-v1/;
/plugin/;

/ {
        compatible = "brcm,bcm2835";

        fragment@0 {
                target = <&i2c1>;
                __overlay__ {
                        #address-cells = <1>;
                        #size-cells = <0>;
                        status = "okay";

                        rpi-sense@46 {
                                compatible = "rpi,rpi-sense";
                                reg = <0x46>;
                                keys-int-gpios = <&gpio 23 1>;
                                status = "okay";
                        };

                        [...省略]
                };
        };
};

Sense HAT GPIO Driver

  • drivers/mfd/rpisense-core.c 
    static int rpisense_probe(struct i2c_client *i2c,
                               const struct i2c_device_id *id)
{
        [...省略]

        rpisense_js = &rpisense->joystick;
        rpisense_js->keys_desc = devm_gpiod_get(&i2c->dev,
                                                "keys-int", GPIOD_IN);
        if (IS_ERR(rpisense_js->keys_desc)) {
                dev_warn(&i2c->dev, "Failed to get keys-int descriptor.\n");
                rpisense_js->keys_desc = gpio_to_desc(23);
                if (rpisense_js->keys_desc == NULL) {
                        dev_err(&i2c->dev, "GPIO23 fallback failed.\n");
                        return PTR_ERR(rpisense_js->keys_desc);
                }
        }
        rpisense_client_dev_register(rpisense, "rpi-sense-js",
                                     &(rpisense->joystick.pdev));
        rpisense_client_dev_register(rpisense, "rpi-sense-fb",
                                     &(rpisense->framebuffer.pdev));

        return 0;
}
    images/DTS_GPIO_Function_Call_Dump.png 
    * static int rpisense_probe(struct i2c_client *i2c, const struct i2c_device_id *id)
  * rpisense_js->keys_desc = devm_gpiod_get(&i2c->dev, "keys-int", GPIOD_IN);
    * return devm_gpiod_get_index(dev, con_id, 0, flags);
      * desc = gpiod_get_index(dev, con_id, idx, flags);
        * desc = of_find_gpio(dev, con_id, idx, &lookupflags);
          * snprintf(prop_name, sizeof(prop_name), "%s-%s", con_id,           // "keys-int-gpios"
          * desc = of_get_named_gpiod_flags(dev->of_node, prop_name, idx, &of_flags);
        * status = gpiod_request(desc, con_id ? con_id : devname);
        * status = gpiod_configure_flags(desc, con_id, lookupflags, flags);
  * rpisense_client_dev_register(rpisense, "rpi-sense-js", &(rpisense->joystick.pdev));
  • drivers/input/joystick/rpisense-js.c 
    static int rpisense_js_probe(struct platform_device *pdev)
{
        int ret;
        int i;
        struct rpisense_js *rpisense_js;

        rpisense = rpisense_get_dev();
        rpisense_js = &rpisense->joystick;

        INIT_WORK(&rpisense_js->keys_work_s, keys_work_fn);

        rpisense_js->keys_dev = input_allocate_device();
        if (!rpisense_js->keys_dev) {
                dev_err(&pdev->dev, "Could not allocate input device.\n");
                return -ENOMEM;
        }

        rpisense_js->keys_dev->evbit[0] = BIT_MASK(EV_KEY);
        for (i = 0; i < ARRAY_SIZE(keymap); i++) {
                set_bit(keymap[i],
                        rpisense_js->keys_dev->keybit);
        }

        rpisense_js->keys_dev->name = "Raspberry Pi Sense HAT Joystick";
        rpisense_js->keys_dev->phys = "rpi-sense-joy/input0";
        rpisense_js->keys_dev->id.bustype = BUS_I2C;
        rpisense_js->keys_dev->evbit[0] = BIT_MASK(EV_KEY) | BIT_MASK(EV_REP);
        rpisense_js->keys_dev->keycode = keymap;
        rpisense_js->keys_dev->keycodesize = sizeof(unsigned char);
        rpisense_js->keys_dev->keycodemax = ARRAY_SIZE(keymap);

        ret = input_register_device(rpisense_js->keys_dev);
        if (ret) {
                dev_err(&pdev->dev, "Could not register input device.\n");
                goto err_keys_alloc;
        }

        ret = gpiod_direction_input(rpisense_js->keys_desc);
        if (ret) {
                dev_err(&pdev->dev, "Could not set keys-int direction.\n");
                goto err_keys_reg;
        }

        rpisense_js->keys_irq = gpiod_to_irq(rpisense_js->keys_desc);
        if (rpisense_js->keys_irq < 0) {
                dev_err(&pdev->dev, "Could not determine keys-int IRQ.\n");
                ret = rpisense_js->keys_irq;
                goto err_keys_reg;
        }

        ret = devm_request_irq(&pdev->dev, rpisense_js->keys_irq,
                               keys_irq_handler, IRQF_TRIGGER_RISING,
                               "keys", &pdev->dev);
        if (ret) {
                dev_err(&pdev->dev, "IRQ request failed.\n");
                goto err_keys_reg;
        }
        return 0;
err_keys_reg:
        input_unregister_device(rpisense_js->keys_dev);
err_keys_alloc:
        input_free_device(rpisense_js->keys_dev);
        return ret;
}