解析linux或android添加文件系统的属性接口的方法

  #include <linux/of_gpio.h>  #include <linux/gpio.h>  #include <linux/delay.h>    #include <linux/module.h>  #include <linux/types.h>  #include <linux/kobject.h>  

  unsigned int Gpio134_OtgID = 134; //定义全局变量  static unsigned int otgid_status = 1;  …

  //add zhaojr gpio134 control OTG ID for host or device mode   static ssize_t setotgid_store(struct device *dev, struct device_attribute *attr,const char *buf, size_t count)         {   unsigned int ret=0;   pr_err("%s: n", __func__);    //ret = kstrtoint(buf, 10, &otgid_status);   ret = kstrtouint(buf, 10, &otgid_status);   //sscanf(buf, "%lu", &otgid_status);   if (ret < 0){    pr_err("%s::kstrtouint() failed n", __func__);   }   //sscanf(buf, "%d", &otgid_status);   pr_err("%s: otgid_status=%d n", __func__,otgid_status);    if(otgid_status > 0){    gpio_set_value(Gpio134_OtgID, 1);    }else{    gpio_set_value(Gpio134_OtgID, 0);    }   return count;  }  static ssize_t setotgid_show(struct device *dev,struct device_attribute *attr, char *buf)    {   pr_err("%s: n", __func__);    return sprintf(buf, "%dn",otgid_status);  }  //static DEVICE_ATTR_RW(setotgid);  /*struct device_attribute dev_attr_setotgid = {         .attr = {.name ="setotgid",           .mode = 0664},       .show = setotgid_show,           .store = setotgid_store,      };*/   //setotgid的一致性，第一个参数setotgid和setotgid_show、setotgid_store前钻必须保持一致  static DEVICE_ATTR(setotgid, 0664, setotgid_show, setotgid_store);   //end zhaojr add  static struct device_attribute *android_usb_attributes[] = {   &dev_attr_state,   &dev_attr_setotgid, //setotgid跟DEVICE_ATTR定义的name必须保持一致   NULL  };    

  static int mdss_mdp_probe(struct platform_device *pdev)  {  ....................................................................................  //zhaojr add for gpio134 to usb host or device mode   ret_status=gpio_request(Gpio134_OtgID, "Gpio134-OtgID");   if(ret_status<0){    pr_err("usb gadget configfs %s::Gpio134_OtgID gpio_request failedn",__func__);     }   pr_err("android_device_create()::Gpio134_OtgID gpio_request OKn");    gpio_direction_output(Gpio134_OtgID,1);   if(otgid_status > 0){ //有自定义初始化状态就添加上这个判断，没有就不需要添加if else操作    pr_err("%s-Gpio134_OtgID pin set 1n", __func__);    gpio_set_value(Gpio134_OtgID, 1);     //msleep(5);   }else{    pr_err("%s-Gpio134_OtgID pin set 0n", __func__);    gpio_set_value(Gpio134_OtgID, 0);     //msleep(5);   }   //end zhaojr add  ................................................................  }    

  static int mdss_mdp_remove(struct platform_device *pdev)  {   struct mdss_data_type *mdata = platform_get_drvdata(pdev);   if (!mdata)    return -ENODEV;    pr_err("%sn", __func__);   gpio_free(Gpio134_OtgID); //zhaojr add free gpio otgid pin   ........................................................  }

  #include <linux/of_gpio.h>  #include <linux/gpio.h>  #include <linux/delay.h>    #include <linux/module.h>  #include <linux/types.h>  #include <linux/kobject.h>

  // add zhaojr gpio63 for close or speaker pa enable  struct kobject *spk_pa_kobj = NULL;  unsigned int gpio63_spk_pa_gpio; //for speaker pa ic enable  //extern unsigned int gpio63_spk_pa_gpio;  static unsigned int SpkPa_Gpio_Enable = 0;  static ssize_t spkpaon_store(struct device *dev, struct device_attribute *attr,const char *buf, size_t count)    {   unsigned int ret=0;   //ret = kstrtoint(buf, 10, &backlight_enable);   ret = kstrtouint(buf, 10, &SpkPa_Gpio_Enable);   if (ret < 0){   pr_err("%s::kstrtouint() failed n", __func__);   }   pr_err("%s: SpkPa_Gpio_Enable=%d n", __func__,SpkPa_Gpio_Enable);    if(SpkPa_Gpio_Enable > 0){   //gpio_set_value(gpio63_spk_pa_gpio, 1);    pr_err("%s: gpio_set_value gpio63 speaker pa enable n", __func__);   //功放打开的时序   gpio_set_value(gpio63_spk_pa_gpio,0);   udelay(8);   gpio_set_value(gpio63_spk_pa_gpio,1);   udelay(8);   gpio_set_value(gpio63_spk_pa_gpio,0);   udelay(8);   gpio_set_value(gpio63_spk_pa_gpio,1);   //sdm660_cdc->ext_spk_pa_set = true;   }else{   pr_err("%s: gpio_set_value gpio63 speaker pa disable n", __func__);   //功放关闭的时序   gpio_set_value(gpio63_spk_pa_gpio,0);   udelay(600);   //sdm660_cdc->ext_spk_pa_set = false;    }   return count;  }  static ssize_t spkpaon_show(struct device *dev,struct device_attribute *attr, char *buf)   {    return sprintf(buf, "%dn",SpkPa_Gpio_Enable);  }   static DEVICE_ATTR(spkpaon, 0664, spkpaon_show, spkpaon_store);  static struct attribute *spkpa_attributes[] = {   &dev_attr_spkpaon.attr,   NULL  };  static const struct attribute_group apkpa_attr_group = {   .attrs = spkpa_attributes,   NULL  };  //end zhaojr add

  static int msm_anlg_cdc_probe(struct platform_device *pdev)  {   int ret = 0;   struct sdm660_cdc_priv *sdm660_cdc = NULL;   struct sdm660_cdc_pdata *pdata;   int adsp_state;   ..................................   dev_set_drvdata(&pdev->dev, sdm660_cdc);   //kangting add   sdm660_cdc->spk_pa_gpio = of_get_named_gpio(pdev->dev.of_node, "qcom,speaker-pa", 0);   if (!gpio_is_valid(sdm660_cdc->spk_pa_gpio))   pr_err("%s, sdm660_cdc->spk_pa_gpio not specifiedn",__func__);   else{   pr_err("%s, sdm660_cdc->spk_pa_gpio is %dn",__func__,sdm660_cdc->spk_pa_gpio);   ret = gpio_request(sdm660_cdc->spk_pa_gpio, "spk_pa");   if (ret) {   pr_err("request spk_pa_gpio failed, ret=%dn",ret);   gpio_free(sdm660_cdc->spk_pa_gpio);   }   }   //kangting end   ret = snd_soc_register_codec(&pdev->dev,     &soc_codec_dev_sdm660_cdc,     msm_anlg_cdc_i2s_dai,     ARRAY_SIZE(msm_anlg_cdc_i2s_dai));   if (ret) {   dev_err(&pdev->dev,   "%s:snd_soc_register_codec failed with error %dn",   __func__, ret);   goto err_supplies;   }   BLOCKING_INIT_NOTIFIER_HEAD(&sdm660_cdc->notifier);   BLOCKING_INIT_NOTIFIER_HEAD(&sdm660_cdc->notifier_mbhc);   //add by zhaojr   gpio63_spk_pa_gpio = sdm660_cdc->spk_pa_gpio; //将设备树种定义的IO口号获取进来   spk_pa_kobj = kobject_create_and_add("spk_pa", NULL); //创建/sys/spk_pa/目录   ret = sysfs_create_group(spk_pa_kobj, &apkpa_attr_group); //创建/sys/class/spk_pa/spkpaon节点   if (ret)   dev_err(&pdev->dev,"%s:sysfs_create_group failed with errorn",__func__);   //end zhaojr add    ....................................

  static int msm_anlg_cdc_remove(struct platform_device *pdev)  {   struct sdm660_cdc_priv *sdm660_cdc = dev_get_drvdata(&pdev->dev);   struct sdm660_cdc_pdata *pdata = sdm660_cdc->dev->platform_data;   int count;   //add by zhaojr //释放资源   gpio_free(sdm660_cdc->spk_pa_gpio);   kobject_put(spk_pa_kobj); //关键函数   sysfs_remove_group(spk_pa_kobj, &apkpa_attr_group); //关键函数   //end zhaojr add   for (count = 0; count < sdm660_cdc->child_count &&   count < ANLG_CDC_CHILD_DEVICES_MAX; count++)   platform_device_unregister(   sdm660_cdc->pdev_child_devices[count]);   snd_soc_unregister_codec(&pdev->dev);   msm_anlg_cdc_disable_supplies(sdm660_cdc, pdata);   wcd9xxx_spmi_irq_exit();   devm_kfree(&pdev->dev, sdm660_cdc);   return 0;  }