list = of_get_property(np, “rockchip,pins“, &size); 解析代码

这段代码用于从设备树(Device Tree)中获取指定节点的属性数据。具体解析如下:

  1. 函数原型
    
    

    c

    const void *of_get_property(const struct device_node *np, const char *name, int *lenp);
    • 功能:从设备树节点 np 中读取名为 name 的属性值。
    • 返回值
      • 成功时返回属性数据的指针(const void*)。
      • 失败时(属性不存在)返回 NULL
    • 参数
      • np: 指向目标设备树节点的指针(struct device_node*)。
      • name: 要查询的属性名(如 "rockchip,pins")。
      • lenp: 输出参数,返回属性值的字节长度。
  2. 代码解析
    list = of_get_property(np, "rockchip,pins", &size);
    • 操作:从节点 np 中读取 rockchip,pins 属性。
    • 结果
      • list 指向属性数据的内存地址(如引脚配置的二进制数据)。
      • size 被赋值为属性数据的实际长度(字节)。
  3. 典型使用场景
    • 在Linux驱动中解析硬件配置(如GPIO、时钟、引脚复用)。
    • 示例(Rockchip平台引脚配置):
      
      

      pins {
          rockchip,pins = [
          /* 每个条目表示一个引脚的配置(复用、电平等) */
          0x00 0x01 0x02 0x03,
          ...
          ];
      };

  4. 注意事项
    • 错误处理:需检查 list 是否为 NULL,避免空指针解引用。
    • 数据类型:属性值通常是二进制数据,需按平台规范解析(如Rockchip的pin_config结构)。
    • 内存管理:属性数据由内核管理,无需手动释放。

总结:此代码从设备树节点 np 中提取 rockchip,pins 属性的二进制数据到 list,并通过 size 返回数据长度,用于后续硬件配置解析。

static int rk_multicodecs_probe(struct platform_device *pdev) { struct snd_soc_card *card; struct device_node *np = pdev->dev.of_node; struct snd_soc_dai_link *link; struct snd_soc_dai_link_component *cpus; struct snd_soc_dai_link_component *platforms; struct snd_soc_dai_link_component *codecs; struct multicodecs_data *mc_data; struct of_phandle_args args; struct device_node *node; struct input_dev *input; u32 val; int count, value; int ret = 0, i = 0, idx = 0; const char *prefix = "rockchip,"; ret = wait_locked_card(np, &pdev->dev); if (ret < 0) { dev_err(&pdev->dev, "check_lock_card failed: %d\n", ret); return ret; } mc_data = devm_kzalloc(&pdev->dev, sizeof(*mc_data), GFP_KERNEL); if (!mc_data) return -ENOMEM; cpus = devm_kzalloc(&pdev->dev, sizeof(*cpus), GFP_KERNEL); if (!cpus) return -ENOMEM; platforms = devm_kzalloc(&pdev->dev, sizeof(*platforms), GFP_KERNEL); if (!platforms) return -ENOMEM; card = &mc_data->snd_card; card->dev = &pdev->dev; /* Parse the card name from DT */ ret = snd_soc_of_parse_card_name(card, "rockchip,card-name"); if (ret < 0) return ret; link = &mc_data->dai_link; link->name = "dailink-multicodecs"; link->stream_name = link->name; link->init = rk_dailink_init; link->ops = &rk_ops; link->cpus = cpus; link->platforms = platforms; link->num_cpus = 1; link->num_platforms = 1; link->ignore_pmdown_time = 1; card->dai_link = link; card->num_links = 1; card->dapm_widgets = mc_dapm_widgets; card->num_dapm_widgets = ARRAY_SIZE(mc_dapm_widgets); card->controls = mc_controls; card->num_controls = ARRAY_SIZE(mc_controls); card->num_aux_devs = 0; count = of_count_phandle_with_args(np, "rockchip,codec", NULL); if (count < 0) return -EINVAL; /* refine codecs, remove unavailable node */ for (i = 0; i < count; i++) { node = of_parse_phandle(np, "rockchip,codec", i); if (!node) return -ENODEV; if (of_device_is_available(node)) idx++; } if (!idx) return -ENODEV; codecs = devm_kcalloc(&pdev->dev, idx, sizeof(*codecs), GFP_KERNEL); link->codecs = codecs; link->num_codecs = idx; idx = 0; for (i = 0; i < count; i++) { node = of_parse_phandle(np, "rockchip,codec", i); if (!node) return -ENODEV; if (!of_device_is_available(node)) continue; ret = of_parse_phandle_with_fixed_args(np, "rockchip,codec", 0, i, &args); if (ret) return ret; codecs[idx].of_node = node; ret = snd_soc_get_dai_name(&args, &codecs[idx].dai_name); if (ret) return ret; idx++; } /* Only reference the codecs[0].of_node which maybe as master. */ rk_multicodecs_parse_daifmt(np, codecs[0].of_node, mc_data, prefix); link->cpus->of_node = of_parse_phandle(np, "rockchip,cpu", 0); if (!link->cpus->of_node) return -ENODEV; link->platforms->of_node = link->cpus->of_node; mc_data->mclk_fs = DEFAULT_MCLK_FS; if (!of_property_read_u32(np, "rockchip,mclk-fs", &val)) mc_data->mclk_fs = val; mc_data->mclk_adapt = 0; if (!of_property_read_u32(np, "rockchip,mclk-adapt", &val)) mc_data->mclk_adapt = val; dev_err(&pdev->dev, "%s mclk_adapt=%d\n", __func__, mc_data->mclk_adapt); mc_data->codec_hp_det = of_property_read_bool(np, "rockchip,codec-hp-det"); mc_data->adc = devm_iio_channel_get(&pdev->dev, "adc-detect"); if (IS_ERR(mc_data->adc)) { if (PTR_ERR(mc_data->adc) != -EPROBE_DEFER) { mc_data->adc = NULL; dev_warn(&pdev->dev, "Failed to get ADC channel"); } } else { if (mc_data->adc->channel->type != IIO_VOLTAGE) return -EINVAL; if (device_property_read_u32(&pdev->dev, "keyup-threshold-microvolt", &mc_data->keyup_voltage)) { dev_warn(&pdev->dev, "Invalid or missing keyup voltage\n"); return -EINVAL; } mc_data->keyup_voltage /= 1000; ret = mc_keys_load_keymap(&pdev->dev, mc_data); if (ret) return ret; input = devm_input_allocate_device(&pdev->dev); if (IS_ERR(input)) { dev_err(&pdev->dev, "failed to allocate input device\n"); return PTR_ERR(input); } input_set_drvdata(input, mc_data); input->name = "headset-keys"; input->phys = "headset-keys/input0"; input->id.bustype = BUS_HOST; input->id.vendor = 0x0001; input->id.product = 0x0001; input->id.version = 0x0100; __set_bit(EV_KEY, input->evbit); for (i = 0; i < mc_data->num_keys; i++) __set_bit(mc_data->map[i].keycode, input->keybit); if (device_property_read_bool(&pdev->dev, "autorepeat")) __set_bit(EV_REP, input->evbit); mc_data->input = input; ret = mc_keys_setup_polling(mc_data, mc_keys_poll); if (ret) { dev_err(&pdev->dev, "Unable to set up polling: %d\n", ret); return ret; } if (!device_property_read_u32(&pdev->dev, "poll-interval", &value)) mc_set_poll_interval(mc_data->poller, value); ret = input_register_device(mc_data->input); if (ret) { dev_err(&pdev->dev, "Unable to register input device: %d\n", ret); return ret; } } INIT_DEFERRABLE_WORK(&mc_data->handler, adc_jack_handler); mc_data->spk_ctl_gpio = devm_gpiod_get_optional(&pdev->dev, "spk-con", GPIOD_OUT_LOW); if (IS_ERR(mc_data->spk_ctl_gpio)) return PTR_ERR(mc_data->spk_ctl_gpio); mc_data->hp_ctl_gpio = devm_gpiod_get_optional(&pdev->dev, "hp-con", GPIOD_OUT_LOW); if (IS_ERR(mc_data->hp_ctl_gpio)) return PTR_ERR(mc_data->hp_ctl_gpio); mc_data->hp_det_gpio = devm_gpiod_get_optional(&pdev->dev, "hp-det", GPIOD_IN); if (IS_ERR(mc_data->hp_det_gpio)) return PTR_ERR(mc_data->hp_det_gpio); mc_data->extcon = devm_extcon_dev_allocate(&pdev->dev, headset_extcon_cable); if (IS_ERR(mc_data->extcon)) { dev_err(&pdev->dev, "allocate extcon failed\n"); return PTR_ERR(mc_data->extcon); } ret = devm_extcon_dev_register(&pdev->dev, mc_data->extcon); if (ret) { dev_err(&pdev->dev, "failed to register extcon: %d\n", ret); return ret; } ret = snd_soc_of_parse_audio_routing(card, "rockchip,audio-routing"); if (ret < 0) dev_warn(&pdev->dev, "Audio routing invalid/unspecified\n"); snd_soc_card_set_drvdata(card, mc_data); ret = devm_snd_soc_register_card(&pdev->dev, card); if (ret == -EPROBE_DEFER) return -EPROBE_DEFER; if (ret) { dev_err(&pdev->dev, "card register failed %d\n", ret); return ret; } platform_set_drvdata(pdev, card); return ret; }
08-06
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