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#include #include #include #include #include
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：
unsignedintGpio134_OtgID=134;//定义全局变量 staticunsignedintotgid_status=1; …
3、定义文件系统的读写函数：
//addzhaojrgpio134controlOTGIDforhostordevicemode
staticssize_tsetotgid_store(structdevice*dev,structdevice_attribute*attr,constchar*buf,size_tcount)
{
unsignedintret=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);
}
returncount;
}
staticssize_tsetotgid_show(structdevice*dev,structdevice_attribute*attr,char*buf)
{
pr_err("%s:\n",__func__);
returnsprintf(buf,"%d\n",otgid_status);
}
//staticDEVICE_ATTR_RW(setotgid);
/*structdevice_attributedev_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
staticDEVICE_ATTR(setotgid,0664,setotgid_show,setotgid_store);
//endzhaojradd
staticstructdevice_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
staticintmdss_mdp_probe(structplatform_device*pdev)
{
....................................................................................
//zhaojraddforgpio134tousbhostordevicemode
ret_status=gpio_request(Gpio134_OtgID,"Gpio134-OtgID");
if(ret_status<0){
pr_err("usbgadgetconfigfs%s::Gpio134_OtgIDgpio_requestfailed\n",__func__);
}
pr_err("android_device_create()::Gpio134_OtgIDgpio_requestOK\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ifelse操作
pr_err("%s-Gpio134_OtgIDpinset1\n",__func__);
gpio_set_value(Gpio134_OtgID,1);
//msleep(5);
}else{
pr_err("%s-Gpio134_OtgIDpinset0\n",__func__);
gpio_set_value(Gpio134_OtgID,0);
//msleep(5);
}
//endzhaojradd
................................................................
}
5、在remove()函数中添加资源的释放
staticintmdss_mdp_remove(structplatform_device*pdev)
{
structmdss_data_type*mdata=platform_get_drvdata(pdev);
if(!mdata)
return-ENODEV;
pr_err("%s\n",__func__);
gpio_free(Gpio134_OtgID);//zhaojraddfreegpiootgidpin
........................................................
}
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#include #include #include #include #include
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：
//addzhaojrgpio63forcloseorspeakerpaenable
structkobject*spk_pa_kobj=NULL;
unsignedintgpio63_spk_pa_gpio;//forspeakerpaicenable
//externunsignedintgpio63_spk_pa_gpio;
staticunsignedintSpkPa_Gpio_Enable=0;
staticssize_tspkpaon_store(structdevice*dev,structdevice_attribute*attr,constchar*buf,size_tcount)
{
unsignedintret=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_valuegpio63speakerpaenable\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_valuegpio63speakerpadisable\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;
}
returncount;
}
staticssize_tspkpaon_show(structdevice*dev,structdevice_attribute*attr,char*buf)
{
returnsprintf(buf,"%d\n",SpkPa_Gpio_Enable);
}
staticDEVICE_ATTR(spkpaon,0664,spkpaon_show,spkpaon_store);
staticstructattribute*spkpa_attributes[]={
&dev_attr_spkpaon.attr,
NULL
};
staticconststructattribute_groupapkpa_attr_group={
.attrs=spkpa_attributes,
NULL
};
//endzhaojradd
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：msm8953audio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
staticintmsm_anlg_cdc_probe(structplatform_device*pdev)
{
intret=0;
structsdm660_cdc_priv*sdm660_cdc=NULL;
structsdm660_cdc_pdata*pdata;
intadsp_state;
..................................
dev_set_drvdata(&pdev->dev,sdm660_cdc);
//kangtingadd
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_gpionotspecified\n",__func__);
else{
pr_err("%s,sdm660_cdc->spk_pa_gpiois%d\n",__func__,sdm660_cdc->spk_pa_gpio);
ret=gpio_request(sdm660_cdc->spk_pa_gpio,"spk_pa");
if(ret){
pr_err("requestspk_pa_gpiofailed,ret=%d\n",ret);
gpio_free(sdm660_cdc->spk_pa_gpio);
}
}
//kangtingend
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_codecfailedwitherror%d\n",
__func__,ret);
gotoerr_supplies;
}
BLOCKING_INIT_NOTIFIER_HEAD(&sdm660_cdc->notifier);
BLOCKING_INIT_NOTIFIER_HEAD(&sdm660_cdc->notifier_mbhc);
//addbyzhaojr
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_groupfailedwitherror\n",__func__);
//endzhaojradd
....................................
4、在remove函数中释放资源
staticintmsm_anlg_cdc_remove(structplatform_device*pdev)
{
structsdm660_cdc_priv*sdm660_cdc=dev_get_drvdata(&pdev->dev);
structsdm660_cdc_pdata*pdata=sdm660_cdc->dev->platform_data;
intcount;
//addbyzhaojr//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
//endzhaojradd
for(count=0;countchild_count&&
countpdev_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);
return0;
}
总结
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