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第一種：
1、添加關鍵頭文件：
#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、在已經存在驅動文件中搜索"DEVICE_ATTR"關鍵字，如果存在，直接參考已經存在的方法添加一個即可，如下：
unsigned int Gpio134_OtgID = 134; //定義全局變量 static unsigned int otgid_status = 1; …
3、定義文件系統的讀寫函數：
//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);
/*struct device_attribute dev_attr_setotgid = {
.attr = {.name ="setotgid",
.mode = 0664},
.show = setotgid_show,
.store = setotgid_store,
};*/
//setotgid的一致性，第一個參數setotgid和setotgid_show、setotgid_store前鉆必須保持一致
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定義的name必須保持一致
NULL
};
4、在probe()函數中定義針對具體GPIO管腳的請求和初始化
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){ //有自定義初始化狀態就添加上這個判斷，沒有就不需要添加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()函數中添加資源的釋放
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
........................................................
}
第二種方法：
在要添加驅動文件中沒有搜索"DEVICE_ATTR"關鍵字的情況，如添加音頻功放打開和關閉的控制接口：
1、添加關鍵頭文件：
#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、定義全局變量和定義打開和關閉的接口并組織屬性數組：
// 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__);
//功放打開的時序
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__);
//功放關閉的時序
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()函數中添加文件系統屬性接口的注冊：
在注冊的時候并不需要對功放進行初始化，所以probe()函數中并沒有對sdm660_cdc->spk_pa_gpio(GPIO63)，只操作了請求。具體的請求操作請參考：msm8953 audio部分的EAR和Speaker輸出的聲音配置中的音頻部分的
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; //將設備樹種定義的IO口號獲取進來
spk_pa_kobj = kobject_create_and_add("spk_pa", NULL); //創建/sys/spk_pa/目錄
ret = sysfs_create_group(spk_pa_kobj, &apkpa_attr_group); //創建/sys/class/spk_pa/spkpaon節點
if (ret)
dev_err(&pdev->dev,"%s:sysfs_create_group failed with error\n",__func__);
//end zhaojr add
....................................
4、在remove函數中釋放資源
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 //釋放資源
gpio_free(sdm660_cdc->spk_pa_gpio);
kobject_put(spk_pa_kobj); //關鍵函數
sysfs_remove_group(spk_pa_kobj, &apkpa_attr_group); //關鍵函數
//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;
}
總結
到此這篇關于解析linux或android添加文件系統的屬性接口的方法的文章就介紹到這了,更多相關linux 文件系統的屬性接口內容請搜索億速云以前的文章或繼續瀏覽下面的相關文章希望大家以后多多支持億速云！
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