瑞芯微RK3576 ADC驱动调试详解｜从基础概念到设备数配置/驱动/调试一站通关

ido-evb7609-v1a-mipi.dts  └── ido-evb7609-v1a.dtsi        ├── rk3576.dtsi        ├── rk3576-linux.dtsi        ├── ido-som7608.dtsi        │     └── ido-evb7609-v1a-mipi.dtsi  ← SARADC 使能处        └── 其他 dtsi...

&saradc {    status = "okay";    vref-supply = <&vcca_1v8_s0>;};

/ {    adc_keys: adc-keys {        compatible = "adc-keys";        io-channels = <&saradc 1>;          /* 使用通道 1 */        io-channel-names = "buttons";        keyup-threshold-microvolt = <1800000>;  /* 按键释放阈值 1.8V */        poll-interval = <100>;              /* 轮询间隔 100ms */        vol-up-key {            label = "volume up";            linux,code = ;            press-threshold-microvolt = <17000>;    /* ~17mV */        };        vol-down-key {            label = "volume down";            linux,code = ;            press-threshold-microvolt = <417000>;   /* ~417mV */        };        menu-key {            label = "menu";            linux,code = ;            press-threshold-microvolt = <890000>;   /* ~890mV */        };        back-key {            label = "back";            linux,code = ;            press-threshold-microvolt = <1235000>;  /* ~1.235V */        };    };};

/ {    battery: battery {        compatible = "simple-battery";        voltage-monitored-battery {            compatible = "voltage-monitored-battery";            io-channels = <&saradc 2>;          /* 使用通道 2 */            io-channel-names = "voltage";            /* OCV 容量曲线 */            ocv-capacity-celsius = <20>;            ocv-capacity-table-0 = <4200 100>, <4000 80>,                                    <3800 50>, <3600 20>,                                    <3400 5>, <3200 0>;        };    };};

#include #include struct my_adc_dev {    struct iio_channel *chan;    struct device *dev;};/* 读取 ADC 电压值（单位：mV） */static int read_adc_value(struct my_adc_dev *priv, int *val){    int ret;    int raw_val, scale_val;    /* 读取原始 ADC 值 */    ret = iio_read_channel_raw(priv->chan, &raw_val);    if (ret < 0) {        dev_err(priv->dev, "Failed to read ADC: %d\n", ret);        return ret;    }    /* 读取比例因子（单位：mV） */    ret = iio_read_channel_scale(priv->chan, &scale_val);    if (ret < 0) {        dev_err(priv->dev, "Failed to read scale: %d\n", ret);        return ret;    }    /* 计算实际电压：raw * scale */    *val = raw_val * scale_val;    return 0;}static int my_adc_probe(struct platform_device *pdev){    struct my_adc_dev *priv;    int val, ret;    priv = devm_kzalloc(&pdev->dev, sizeof(*priv), GFP_KERNEL);    if (!priv)        return -ENOMEM;    priv->dev = &pdev->dev;    /* 获取 IIO 通道（名称需与设备树 io-channel-names 匹配） */    priv->chan = devm_iio_channel_get(&pdev->dev, "voltage");    if (IS_ERR(priv->chan)) {        ret = PTR_ERR(priv->chan);        if (ret != -EPROBE_DEFER)            dev_err(&pdev->dev, "Failed to get IIO channel: %d\n", ret);        return ret;    }    /* 测试读取 */    ret = read_adc_value(priv, &val);    if (ret == 0)        dev_info(&pdev->dev, "ADC value: %d mV\n", val);    platform_set_drvdata(pdev, priv);    return 0;}static const struct of_device_id my_adc_of_match[] = {    { .compatible = "mycompany,my-adc-device" },    { }};static struct platform_driver my_adc_driver = {    .probe = my_adc_probe,    .driver = {        .name = "my-adc",        .of_match_table = my_adc_of_match,    },};module_platform_driver(my_adc_driver);MODULE_LICENSE("GPL");

#include #define SARADC_CTRL     0x00#define SARADC_DATA     0x04#define SARADC_STAS     0x08#define SARADC_EN       BIT(0)#define SARADC_START    BIT(4)struct saradc_regs {    void __iomem *base;    struct clk *clk;};static int saradc_read_channel(struct saradc_regs *regs, int channel){    u32 ctrl;    int timeout = 1000;    /* 使能 ADC */    writel(SARADC_EN, regs->base + SARADC_CTRL);    /* 配置通道并启动转换 */    ctrl = SARADC_EN | SARADC_START | (channel << 6);    writel(ctrl, regs->base + SARADC_CTRL);    /* 等待转换完成 */    while (!(readl(regs->base + SARADC_STAS) & BIT(0))) {        if (--timeout == 0)            return -ETIMEDOUT;        udelay(1);    }    /* 读取结果（10-bit） */    return readl(regs->base + SARADC_DATA) & 0x3ff;}

# 查看 ADC 设备ls /sys/bus/iio/devices/# 读取原始值（10-bit）cat /sys/bus/iio/devices/iio:device0/in_voltage0_raw# 读取比例因子cat /sys/bus/iio/devices/iio:device0/in_voltage0_scale# 计算实际电压# V = raw * scale / 1000000

#include #include #include #include #include #define ADC_PATH "/sys/bus/iio/devices/iio:device0"int read_adc_raw(int channel){    char path[256];    char buf[32];    int fd, val;    snprintf(path, sizeof(path), "%s/in_voltage%d_raw",             ADC_PATH, channel);    fd = open(path, O_RDONLY);    if (fd < 0) {        perror("Failed to open ADC");        return -1;    }    if (read(fd, buf, sizeof(buf)) < 0) {        perror("Failed to read ADC");        close(fd);        return -1;    }    close(fd);    return atoi(buf);}int read_adc_scale(void){    char path[256];    char buf[32];    int fd;    snprintf(path, sizeof(path), "%s/in_voltage_scale", ADC_PATH);    fd = open(path, O_RDONLY);    if (fd < 0)        return -1;    if (read(fd, buf, sizeof(buf)) < 0) {        close(fd);        return -1;    }    close(fd);    return (int)(atof(buf) * 1000000);  /* 转换为微伏 */}int main(void){    int raw, scale, channel = 0;    float voltage;    printf("Reading ADC channel %d...\n", channel);    raw = read_adc_raw(channel);    if (raw < 0) {        printf("Failed to read ADC\n");        return -1;    }    scale = read_adc_scale();    if (scale < 0) {        printf("Failed to read scale\n");        return -1;    }    voltage = (float)raw * scale / 1000000.0;    printf("Raw value: %d\n", raw);    printf("Scale: %d uV/LSB\n", scale);    printf("Voltage: %.3f V\n", voltage);    return 0;}

# 查看 IIO 设备ls /sys/bus/iio/devices/cat /sys/bus/iio/devices/iio:device0/name# 查看所有通道ls /sys/bus/iio/devices/iio:device0/ | grep in_voltage# 读取所有通道值for i in 0 1 2 3; do    echo "Channel $i: $(cat /sys/bus/iio/devices/iio:device0/in_voltage${i}_raw)"done

# 查看按键事件evtest /dev/input/event0# 查看按键映射cat /proc/bus/input/devices# 单独读取 ADC 按键通道值cat /sys/bus/iio/devices/iio:device0/in_voltage1_raw