解析linux或android添加文件系统的属性接口的方法

第一种：

1、添加关键头文件：

#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>

2、在已经存在驱动文件中搜索"DEVICE_ATTR"关键字，如果存在，直接参考已经存在的方法添加一个即可，如下：

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

3、定义文件系统的读写函数：

//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, "%d\n",otgid_status);
}
//static DEVICE_ATTR_RW(setotgid);
 
//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
};

4、在probe()函数中定义针对具体GPIO管脚的请求和初始化

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 failed\n",__func__); 
  }
 pr_err("android_device_create()::Gpio134_OtgID gpio_request OK\n"); 
 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 1\n", __func__);
  gpio_set_value(Gpio134_OtgID, 1); 
  //msleep(5);
 }else{
  pr_err("%s-Gpio134_OtgID pin set 0\n", __func__);
  gpio_set_value(Gpio134_OtgID, 0); 
  //msleep(5);
 }
 //end zhaojr add
................................................................
}

5、在remove()函数中添加资源的释放

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

第二种方法：

在要添加驱动文件中没有搜索"DEVICE_ATTR"关键字的情况，如添加音频功放打开和关闭的控制接口：
1、添加关键头文件：

#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>

2、定义全局变量和定义打开和关闭的接口并组织属性数组：

// 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, "%d\n",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

3、在probe()函数中添加文件系统属性接口的注册：
在注册的时候并不需要对功放进行初始化，所以probe()函数中并没有对sdm660_cdc->spk_pa_gpio(GPIO63)，只操作了请求。具体的请求操作请参考：msm8953 audio部分的EAR和Speaker输出的声音配置中的音频部分的

vendor/qcom/opensource/audio-kernel/asoc/codecs/sdm660_cdc/msm-analog-cdc.c文件操作

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 specified\n",__func__);
 else{
 pr_err("%s, sdm660_cdc->spk_pa_gpio is %d\n",__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=%d\n",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 %d\n",
 __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 error\n",__func__);
 //end zhaojr add 
 ....................................

4、在remove函数中释放资源

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;
}

总结

到此这篇关于解析linux或android添加文件系统的属性接口的方法的文章就介绍到这了,更多相关linux 文件系统的属性接口内容请搜索编程网以前的文章或继续浏览下面的相关文章希望大家以后多多支持编程网！