RK3576开发板PWM驱动教程（上）触觉智能开发板演示基础原理/设备树/红外收发捕获解析

&pwm1_6ch_5 {    status = "okay";};

/ {    /* 背光设备 */    backlight: backlight {        compatible = "pwm-backlight";        pwms = <&pwm1_6ch_5 0 25000 0>;  /* PWM, channel, period(ns), polarity */        /* 亮度等级表 */        brightness-levels = <              0  20  20  21  21  22  22  23             23  24  24  25  25  26  26  27             /* ... 更多等级 ... */            248 249 250 251 252 253 254 255        >;        default-brightness-level = <200>;        /* 电源控制 */        enable-gpios = <&gpio4 RK_PA1 GPIO_ACTIVE_HIGH>;    };    /* 风扇 PWM 控制 */    fan: pwm-fan {        compatible = "pwm-fan";        pwms = <&pwm2 0 40000 0>;  /* 25KHz PWM 频率 */        /* 温度与转速曲线 */        cooling-levels = <0 100 150 200 255>;        #cooling-cells = <2>;    };};

&pinctrl {    pwm1 {        pwm1m0_pins: pwm1m0-pins {            rockchip,pins =                <1 RK_PB6 2 &pcfg_pull_none>;        };    };    pwm2 {        pwm2m0_pins: pwm2m0-pins {            rockchip,pins =                <1 RK_PB7 2 &pcfg_pull_none>;        };    };};

#include struct pwm_capture {    unsigned int period;      /* 捕获到的周期 (ns) */    unsigned int duty_cycle;  /* 捕获到的占空比 (ns) */};/* 捕获外部 PWM 信号 */int pwm_capture(struct pwm_device *pwm, struct pwm_capture *result, unsigned long timeout);

#include #include #include struct my_pwm_capture_dev {    struct pwm_device *pwm;    struct device *dev;};static int my_capture_probe(struct platform_device *pdev){    struct my_pwm_capture_dev *priv;    int ret;    priv = devm_kzalloc(&pdev->dev, sizeof(*priv), GFP_KERNEL);    if (!priv)        return -ENOMEM;    priv->dev = &pdev->dev;    /* 获取 PWM 设备（与 PWM 输出共用节点） */    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;    }    platform_set_drvdata(pdev, priv);    dev_info(&pdev->dev, "PWM capture device initialized\n");    return 0;}/* 读取捕获结果 */static int my_capture_read(struct my_pwm_capture_dev *priv,                           unsigned int *period_ns,                           unsigned int *duty_ns){    struct pwm_capture result;    int ret;    /* 捕获外部信号，超时 100ms */    ret = pwm_capture(priv->pwm, &result, 100);    if (ret) {        dev_err(priv->dev, "Failed to capture PWM: %d\n", ret);        return ret;    }    *period_ns = result.period;    *duty_ns = result.duty_cycle;    dev_info(priv->dev, "Captured: period=%uns, duty=%uns\n",             result.period, result.duty_cycle);    return 0;}/* 计算频率和占空比百分比 */static void my_capture_calc_freq_duty(unsigned int period_ns, unsigned int duty_ns,                                      unsigned int *freq_hz, unsigned int *duty_pct){    if (period_ns == 0)        return;    *freq_hz = 1000000000 / period_ns;    *duty_pct = (duty_ns * 100) / period_ns;}static int my_capture_remove(struct platform_device *pdev){    return 0;}static const struct of_device_id my_capture_of_match[] = {    { .compatible = "mycompany,my-pwm-capture", },    { }};static struct platform_driver my_capture_driver = {    .probe = my_capture_probe,    .remove = my_capture_remove,    .driver = {        .name = "my-pwm-capture",        .of_match_table = my_capture_of_match,    },};module_platform_driver(my_capture_driver);MODULE_LICENSE("GPL");

/ {    /* GPIO 红外接收头 */    ir_receiver: ir-receiver {        compatible = "gpio-ir-receiver";        gpios = <&gpio0 RK_PA5 GPIO_ACTIVE_LOW>;        linux,rc-map-name = "rc-rc6-mce";  /* 使用预定义的按键映射 */        linux,autosuspend-period = <125>;  /* 自动挂起延迟 (ms) */    };};

CONFIG_RC_CORE=yCONFIG_GPIO_IR_RECEIVER=m          # 或 yCONFIG_RC_DECODERS=y               # 包含 NEC、RC5、RC6 等解码器CONFIG_RC_MAP=y

# 按键映射表格式：scancode keycode# scancode: 遥控器发送的原始 NEC 码# keycode: 映射到的 Linux 按键0x12ff01 KEY_POWER0x12ff02 KEY_VOLUMEUP0x12ff03 KEY_VOLUMEDOWN0x12ff04 KEY_UP0x12ff05 KEY_DOWN0x12ff06 KEY_LEFT0x12ff07 KEY_RIGHT0x12ff08 KEY_ENTER

ir-keytable -c                    # 清除现有映射ir-keytable -p NEC -p RC-6        # 启用解码协议ir-keytable -w /etc/rc_keymaps/my_remote.map  # 加载映射

# 查看红外设备ir-keytable# 输出示例：# Found /sys/class/rc/rc0/ with:#   Name: gpio_ir_recv#   Driver: gpio-ir-recv#   Default keymap: rc-rc6-mce#   Input device: /dev/input/event2#   Enabled protocols: nec# 实时监控按键事件ir-keytable -t# 输出示例：# 1234.567890: event type EV_MSC, evscancode = 0x12ff01# 1234.567891: event type EV_KEY, KEY_POWER(116) pressed# 1234.567891: event type EV_KEY, KEY_POWER(116) released# 查看原始事件cat /dev/input/event2 | hexdump# 使用 evtest 测试evtest /dev/input/event2

&pwm2 {    status = "okay";    pinctrl-0 = <&pwm2m0_pins>;    rockchip,pwm-ir-transmit;   /* 使能 IR 发射功能 */};

CONFIG_RC_CORE=y               # 必须启用（IR 发射依赖 rc-core）CONFIG_PWM_ROCKCHIP=y          # 或 m

txbuf[0]: NEC 引导码低电平时间 (μs)，通常 9000txbuf[1]: NEC 引导码高电平时间 (μs)，通常 4500txbuf[2]: 重复码高电平时间 (μs)，通常 2250txbuf[3]: 逻辑 "0" 和 "1" 低电平时间 (μs)，通常 560txbuf[4]: 逻辑 "0" 高电平时间 (μs)，通常 560txbuf[5]: 逻辑 "1" 高电平时间 (μs)，通常 1690txbuf[6]: 32位 NEC 数据

bit[31:24]  bit[23:16]    bit[15:8]       bit[7:0]命令反码    命令码        地址反码        地址码

#include #include #include struct my_pwm_ir_dev {    struct rc_dev *rcdev;    struct platform_device *pdev;};/* NEC 协议红外发射 */static int my_pwm_ir_tx(struct rc_dev *dev, unsigned int *txbuf, unsigned int count){    struct my_pwm_ir_dev *priv = dev->priv;    struct pwm_device *pwm;    int ret;    if (count < 2)        return -EINVAL;    pwm = dev->priv;    if (!pwm)        return -ENODEV;    /* 通过 PWM IR 硬件发射 */    /* 注意：实际发射由 pwm-rockchip 驱动的     * rockchip_pwm_ir_transmit 处理 */    ret = pwm_ir_transmit(pwm, txbuf, count);    if (ret < 0)        dev_err(&dev->dev, "IR transmit failed: %d\n", ret);    return ret;}static int my_pwm_ir_probe(struct platform_device *pdev){    struct my_pwm_ir_dev *priv;    struct rc_dev *rcdev;    int ret;    priv = devm_kzalloc(&pdev->dev, sizeof(*priv), GFP_KERNEL);    if (!priv)        return -ENOMEM;    /* 注册 rc_dev */    rcdev = devm_rc_allocate_device(&pdev->dev, RC_DRIVER_IR_RAW_TX);    if (!rcdev)        return -ENOMEM;    rcdev->driver_name = "my-pwm-ir";    rcdev->device_name = "PWM IR Transmitter";    rcdev->tx_ir = my_pwm_ir_tx;    rcdev->priv = priv;    rcdev->allowed_protocols = RC_BIT_NEC | RC_BIT_NECX | RC_BIT_NEC32;    ret = devm_rc_register_device(&pdev->dev, rcdev);    if (ret) {        dev_err(&pdev->dev, "Failed to register rc device: %d\n", ret);        return ret;    }    priv->rcdev = rcdev;    priv->pdev = pdev;    dev_info(&pdev->dev, "PWM IR transmitter registered\n");    return 0;}static const struct of_device_id my_pwm_ir_of_match[] = {    { .compatible = "mycompany,my-pwm-ir", },    { }};static struct platform_driver my_pwm_ir_driver = {    .probe = my_pwm_ir_probe,    .driver = {        .name = "my-pwm-ir",        .of_match_table = my_pwm_ir_of_match,    },};module_platform_driver(my_pwm_ir_driver);MODULE_LICENSE("GPL");

# 使用 ir-ctl 发送 NEC 码# 格式：ir-ctl --transmit= --send="protocol:scancode"# 发送 NEC POWER 键（地址 0x01，命令 0x10）ir-ctl -d /dev/lirc0 --send=nec:0x12ff01# 查看 IR 设备ir-ctl -i# 输出示例：# lirc0: PWM IR Transmitter#   driver: my-pwm-ir#   Features: send#   Allowed protocols: NEC NECX NEC32# 发送重复码（长按效果）ir-ctl -d /dev/lirc0 --send=nec:0x12ff01 --send=nec:0x12ff01 --send=nec:0x12ff01# 使用 evtest 验证（发射 + 接收回路测试）ir-ctl -d /dev/lirc0 --send=nec:0x12ff01ir-keytable -t  # 在另一终端中观察