aosp gpio driver 和 dts 以及键值上报
配置和定义
gpio_power_detect {
compatible = "quectel,gpio_power_detect";
pinctrl-names = "default";
pinctrl-0 = <&gpio_power_detect_active>;
gpio_power_gpio = <&tlmm 95 0x00>;
//otg-power-gpios = <&tlmm 18 0>;
usb-sel-gpios = <&tlmm 66 0>;
debounce = <15>;
linux,code = <172>;
}; struct gpio_power_detect {
struct device *dev;
struct input_dev *p_inputdev;
unsigned int gpio_power_gpio;
unsigned int gpio_power_irq_num;
// struct work_struct power_detect;
struct workqueue_struct *gpio_power_detect_wq;
struct work_struct work;
unsigned int gpio_usb_sel_gpio;
atomic_t state;
unsigned int code;
};driver 和 dts 块之间的绑定
driver 中的 struct of_device_id 中的 compatible 会和 dts 中的 compatible 进行匹配，吻合的情况下， driver 就能从这个 dts 块中读取相应的数据了。 本文的 dts 是 qm215-qrd.dtsi
static struct of_device_id of_device_sc20_gpio_match_table[] =
{
{.compatible = "quectel,gpio_power_detect"},
{},
}; gpio_power_detect {
compatible = "quectel,gpio_power_detect";
...
};driver 配置输入引脚
输入引脚一般需要配置： 引脚方向，中断，上下拉。
- 获取 gpio, driver 中通过 dts 中的相同名称，获取到 gpio，然后申请相应的结构体
dev_struct->gpio_power_gpio = of_get_named_gpio(dev_struct->dev->of_node, "gpio_power_gpio", 0);
gpio_request(dev_struct->gpio_power_gpio, "gpio_power_gpio"); gpio_power_detect {
...
gpio_power_gpio = <&tlmm 95 0x00>;
...
};-
获取中断
dev_struct->gpio_power_irq_num = gpio_to_irq(dev_struct->gpio_power_gpio); -
设置方向
gpio_direction_input(dev_struct->gpio_power_gpio); - 设置上下拉，是通过 dts 来配置的，本文实在
msm8917-pinctrl.dtsi中配置的，然后在qm215-qrd.dtsi中进行引用。tlmm_gpio_power_detect { gpio_power_detect_active: gpio_power_detect_active { mux { pins = "gpio95"; drive-strength = <2>; bias-pull-up; }; }; };
gpio_power_detect {
...
pinctrl-names = "default";
pinctrl-0 = <&gpio_power_detect_active>;
...
};
···
# 配置输出引脚
输出引脚配置比较简单，只要获取 gpio 后，配置方向和初始值即可。
1. 获取 gpio
dev_struct->gpio_usb_sel_gpio = of_get_named_gpio(dev_struct->dev->of_node, "usb-sel-gpios", 0);
if (dev_struct->gpio_usb_sel_gpio < 0){
pr_err("%s: get usb_sel_gpio failed\n", __func__);
return -EINVAL;
}
ret = gpio_request(dev_struct->gpio_usb_sel_gpio, "usb-sel-gpios");
if (ret) {
pr_err("%s: Unable to request usb_sel_spio [%d]\n", __func__, dev_struct->gpio_usb_sel_gpio);
return ret;
} gpio_power_detect {
...
usb-sel-gpios = <&tlmm 66 0>;
...
};
2. 配置位输出
ret = gpio_direction_output(dev_struct->gpio_usb_sel_gpio, 1);
if (ret) {
pr_err("%s: Unable to set direction for usb-sel-gpios [%d]\n", __func__, dev_struct->gpio_usb_sel_gpio);
gpio_free(dev_struct->gpio_usb_sel_gpio);
}
# 配置按键值上报
1. 获取按键值 if(of_property_read_u32(dev_struct->dev->of_node, "linux,code", &dev_struct->code)) {
dev_err(dev_struct->dev, "fail to get linux code\n");
return (-EINVAL);
}
printk("gpio_power_detect probe get key code %d\n", dev_struct->code);
state = gpio_get_value(dev_struct->gpio_power_gpio);
if(state < 0) {
dev_err(dev_struct->dev, "fail to init base_detect state %d\n", state);
return (-EINVAL);
}
atomic_set(&dev_struct->state, state); gpio_power_detect {
...
linux,code = <172>;
};
2. 工作时上报键值 old_state = atomic_read(&dev_struct->state);
new_state = gpio_get_value(dev_struct->gpio_power_gpio);
if (new_state < 0) {
dev_err(dev_struct->dev,
"failed to get bd-gpio state: %d\n", new_state);
return;
}
if(new_state != old_state){
dev_err(dev_struct->dev, "base_detect update state %d", new_state);
atomic_set(&dev_struct->state, new_state);
gpio_set_value(dev_struct->gpio_usb_sel_gpio, new_state);
input_report_key(dev_struct->p_inputdev, dev_struct->code, new_state);
input_sync(dev_struct->p_inputdev);
}
# 注意
本文中使用的 `gpio_request` 属于老的 api，新的 api 一般是 `gpiod` 开头，比如：`gpiod_direction_output`.
如果是按键，为了消抖，dts 中需要考虑 `debounce`，driver 中需要考虑 延迟工作 `struct delayed_work` 。
`DEVICE_ATTR` 可以在 `sys fs` 中添加文件，相关可以参考: https://blog.csdn.net/njuitjf/article/details/16849333
# 参考:
设备树详解
https://blog.csdn.net/qq_28992301/article/details/53321610
在Linux驱动中使用gpio子系统
https://www.jianshu.com/p/f160209bd64b
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https://blog.csdn.net/vincent1995x/article/details/51581711
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http://developer.rokid.com/docs/7-bspguide/pinmuxji_gpio_she_zhi/gpioshe_zhi.html
LinuxGPIO中文文档
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一、初识linux输入子系统
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pm_stay_awake()和pm_relax()的意义
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linux gpio_to_irq()源码分析
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of_property_read_u32
https://biscuitos.github.io/blog/DTS-of_property_read_u32/
如何在一份驱动中上报键值之理解input子系统设备
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INPUT子系统学习 evdev
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