触觉智能RK3576开发板实战（下）PWM驱动开发与温控风扇Demo实战演示

#include #include struct my_pwm_dev {    struct pwm_device *pwm;    struct device *dev;};/* 申请 PWM */static int my_pwm_probe(struct platform_device *pdev){    struct my_pwm_dev *priv;    struct pwm_state state;    int ret;    priv = devm_kzalloc(&pdev->dev, sizeof(*priv), GFP_KERNEL);    if (!priv)        return -ENOMEM;    priv->dev = &pdev->dev;    /* 从设备树获取 PWM */    priv->pwm = devm_pwm_get(&pdev->dev, NULL);    if (IS_ERR(priv->pwm)) {        ret = PTR_ERR(priv->pwm);        if (ret != -EPROBE_DEFER)            dev_err(&pdev->dev, "Failed to get PWM: %d\n", ret);        return ret;    }    /* 配置 PWM 参数 */    pwm_init_state(priv->pwm, &state);    /* 设置周期：25000ns = 40KHz */    state.period = 25000;    /* 设置占空比：50% */    state.duty_cycle = 12500;    /* 使能 PWM */    state.enabled = true;    ret = pwm_apply_state(priv->pwm, &state);    if (ret) {        dev_err(&pdev->dev, "Failed to apply PWM state: %d\n", ret);        return ret;    }    dev_info(&pdev->dev, "PWM initialized: period=%u, duty=%u\n",             state.period, state.duty_cycle);    platform_set_drvdata(pdev, priv);    return 0;}/* 设置占空比 */static int my_pwm_set_duty(struct my_pwm_dev *priv, unsigned int duty_percent){    struct pwm_state state;    u64 duty_cycle;    int ret;    if (duty_percent > 100)        return -EINVAL;    pwm_get_state(priv->pwm, &state);    /* 计算新的占空比 */    duty_cycle = (u64)state.period * duty_percent;    do_div(duty_cycle, 100);    state.duty_cycle = duty_cycle;    state.enabled = (duty_percent > 0);    ret = pwm_apply_state(priv->pwm, &state);    if (ret)        dev_err(priv->dev, "Failed to set PWM duty: %d\n", ret);    return ret;}/* LED 调光函数 */static int my_pwm_set_brightness(struct my_pwm_dev *priv, int brightness){    /* brightness: 0-255 */    int duty = (brightness * 100) / 255;    return my_pwm_set_duty(priv, duty);}static int my_pwm_remove(struct platform_device *pdev){    struct my_pwm_dev *priv = platform_get_drvdata(pdev);    /* 禁用 PWM */    pwm_disable(priv->pwm);    return 0;}static const struct of_device_id my_pwm_of_match[] = {    { .compatible = "mycompany,my-pwm-device", },    { }};static struct platform_driver my_pwm_driver = {    .probe = my_pwm_probe,    .remove = my_pwm_remove,    .driver = {        .name = "my-pwm",        .of_match_table = my_pwm_of_match,    },};module_platform_driver(my_pwm_driver);MODULE_LICENSE("GPL");

# 导出 PWM（如果内核支持 sysfs 接口）echo 0 > /sys/class/pwm/pwmchip0/export# 设置周期（ns）echo 25000 > /sys/class/pwm/pwmchip0/pwm0/period# 设置占空比（ns）echo 12500 > /sys/class/pwm/pwmchip0/pwm0/duty_cycle# 使能 PWMecho 1 > /sys/class/pwm/pwmchip0/pwm0/enable# 修改占空比echo 5000 > /sys/class/pwm/pwmchip0/pwm0/duty_cycle   # 20%echo 20000 > /sys/class/pwm/pwmchip0/pwm0/duty_cycle  # 80%# 禁用 PWMecho 0 > /sys/class/pwm/pwmchip0/pwm0/enable

#include #include #include #include #include #define PWM_PATH "/sys/class/pwm/pwmchip0/pwm0"int pwm_write(const char *file, const char *val){    char path[256];    int fd;    snprintf(path, sizeof(path), "%s/%s", PWM_PATH, file);    fd = open(path, O_WRONLY);    if (fd < 0) {        perror("open");        return -1;    }    if (write(fd, val, strlen(val)) < 0) {        perror("write");        close(fd);        return -1;    }    close(fd);    return 0;}int main(int argc, char *argv[]){    int duty;    char buf[32];    if (argc < 2) {        printf("Usage: %s \n", argv[0]);        return -1;    }    duty = atoi(argv[1]);    if (duty < 0 || duty > 100) {        printf("Duty must be 0-100\n");        return -1;    }    /* 设置周期 25us (40KHz) */    pwm_write("period", "25000");    /* 设置占空比 */    snprintf(buf, sizeof(buf), "%d", duty * 250);    pwm_write("duty_cycle", buf);    /* 使能 PWM */    pwm_write("enable", "1");    printf("PWM set to %d%% duty cycle\n", duty);    return 0;}

/ {    /* 温度传感器 */    thermal-zones {        cpu_thermal: cpu-thermal {            polling-delay-passive = <250>;  /* 被动轮询间隔 */            polling-delay = <1000>;        /* 主动轮询间隔 */            /* 热传感器 */            thermal-sensors = <&tsadc 0>;            trips {                cpu_cool: cpu-cool {                    temperature = <55000>;   /* 55°C */                    hysteresis = <5000>;                    type = "active";                };                cpu_hot: cpu-hot {                    temperature = <70000>;   /* 70°C */                    hysteresis = <5000>;                    type = "active";                };                cpu_crit: cpu-crit {                    temperature = <95000>;   /* 95°C */                    hysteresis = <2000>;                    type = "critical";                };            };            cooling-maps {                map0 {                    trip = <&cpu_cool>;                    cooling-device = <&fan THERMAL_NO_LIMIT 1>;                };                map1 {                    trip = <&cpu_hot>;                    cooling-device = <&fan 2 THERMAL_NO_LIMIT>;                };            };        };    };};

/ {    /* 温度传感器 */    thermal-zones {        cpu_thermal: cpu-thermal {            polling-delay-passive = <250>;  /* 被动轮询间隔 */            polling-delay = <1000>;        /* 主动轮询间隔 */            /* 热传感器 */            thermal-sensors = <&tsadc 0>;            trips {                cpu_cool: cpu-cool {                    temperature = <55000>;   /* 55°C */                    hysteresis = <5000>;                    type = "active";                };                cpu_hot: cpu-hot {                    temperature = <70000>;   /* 70°C */                    hysteresis = <5000>;                    type = "active";                };                cpu_crit: cpu-crit {                    temperature = <95000>;   /* 95°C */                    hysteresis = <2000>;                    type = "critical";                };            };            cooling-maps {                map0 {                    trip = <&cpu_cool>;                    cooling-device = <&fan THERMAL_NO_LIMIT 1>;                };                map1 {                    trip = <&cpu_hot>;                    cooling-device = <&fan 2 THERMAL_NO_LIMIT>;                };            };        };    };};

# 查看 PWM 设备ls /sys/class/pwm/# 查看 PWM 状态cat /sys/kernel/debug/pwm# 查看背光状态cat /sys/class/backlight/backlight/brightnesscat /sys/class/backlight/backlight/max_brightness

# PWM 参数计算# 频率 = 1 / 周期(s)# 占空比 = 高电平时间 / 周期 × 100%# 25KHz 风扇 PWM周期 = 40us = 40000ns# 50% 占空比高电平时间 = 20us

# 配置 PWMpwm-tool -d /sys/class/pwm/pwmchip0/pwm0 \         -p 25000 -c 12500 -e# 调整占空比pwm-tool -d /sys/class/pwm/pwmchip0/pwm0 -c 20000

# 查看红外设备状态ir-keytable# 实时监控按键事件ir-keytable -t# 发送 NEC 红外码ir-ctl -d /dev/lirc0 --send=nec:0x12ff01# 查看 rc-core 调试信息cat /sys/kernel/debug/ir_raw_event# 验证红外接收/发射回路# 终端 1: ir-keytable -t# 终端 2: ir-ctl -d /dev/lirc0 --send=nec:0x12ff01# 观察终端 1 是否收到事件