2.1 LS2K0300驱动舵机（修订1）

原创已于 2025-03-02 09:39:08 修改 · 948 阅读

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#linux #物联网 #嵌入式硬件 #单片机

于 2025-02-27 22:55:23 首次发布

龙芯（ls2k300）专栏收录该内容

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1、配置设备树

修改此文件loongson_2k0300_pai_99_wifi.dts

（1）为什么上述pwms是3个参数，而网上有的是4个参数

因为在dtsi文件里pwm3也就是第4个PWM的属性有这一句#pwm-cells = <2>; 表示PWM3，通道0，有2个参数，此时PWM默认的属性是0--对应的就是极性正常。

（2）为什么要极性反转

因为PWM，应该是高电平持续的时间，所以此时需要设置极性为1--对应的就是极性反转

因而需要设置 pwm_set_polarity(servo.pwm, PWM_POLARITY_INVERSED); // 极性反转

2、驱动模块

#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/init.h>
#include <linux/fs.h>
#include <linux/uaccess.h>
#include <linux/io.h>
#include <linux/cdev.h>
#include <linux/device.h>
#include <linux/of.h>
#include <linux/platform_device.h>
#include <linux/miscdevice.h>

#include <linux/pwm.h>

#define SERVO_MISCMINOR 255
#define SERVO_MISCNAME "servo"

struct Servo_dev{
struct device *dev;
struct pwm_device *pwm;
};

struct Servo_dev servo;

static int pwm_init(struct Servo_dev *servo)
{
servo->pwm = pwm_get(servo->dev, NULL);
if(IS_ERR(servo->pwm)) {
printk("get pwm error\r\n");
goto fail_pwm;
}
return 0;

fail_pwm:
return -ENAVAIL;
}

static const struct file_operations servo_fops = {
.owner = THIS_MODULE,
};

static struct miscdevice servo_miscdev = {
.minor = SERVO_MISCMINOR,
.name = SERVO_MISCNAME,
.fops = &servo_fops,
};

static int servo_probe(struct platform_device *pdev)
{
int ret;
printk("find servo\r\n");

ret = misc_register(&servo_miscdev);
if(ret) {
ret = -EINVAL;
printk("misc register error\r\n");
goto fail_misc;
}

servo.dev = &pdev->dev;

   ret = pwm_init(&servo);
if(ret < 0) {
printk("pwm init error\t\n");
}

//pwm_config(servo.pwm, 500000, 20000000);//--0.5ms
pwm_config(servo.pwm, 1500000, 20000000);//--1.5ms

pwm_set_polarity(servo.pwm, PWM_POLARITY_INVERSED); // 反转极性
pwm_enable(servo.pwm);

return 0;

fail_misc:
return ret;
}

static int servo_remove(struct platform_device *pdev)
{
printk("remove servo\r\n");

misc_deregister(&servo_miscdev);
   pwm_disable(servo.pwm);
pwm_put(servo.pwm);
printk("pwm put finish\r\n");

return 0;
}

static const struct of_device_id servo_of_match[] ={
{.compatible = "loongson,ls2k0300_servo"},
{},
};

static struct platform_driver servo_driver = {
.probe = servo_probe,
.remove = servo_remove,
.driver = {
.name = "servo_pwm",
.of_match_table = servo_of_match,
},
};

module_platform_driver(servo_driver);
MODULE_LICENSE("GPL");
MODULE_AUTHOR("WwuSama");