Method of parsing linux or android to add attribute interface of file system
- 2021-07-26 09:10:20
- OfStack
Type 1:
1. Add key header files:
#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. Search for the keyword "DEVICE_ATTR" in the existing driver file. If it exists, add one directly with reference to the existing method, as follows:
unsigned int Gpio134_OtgID = 134; // Define global variables
static unsigned int otgid_status = 1;
…
3. Define the read and write functions of the file system:
//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 Adj. 1 Cause sex, first 1 Parameters setotgid And setotgid_show , setotgid_store Forward drilling must be maintained 1 To
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 Follow DEVICE_ATTR Defined name Must be maintained 1 To
NULL
};
4. Define requests and initializations for specific GPIO pins in the probe () function
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){ // Add this judgment if there is a custom initialization status, and do not need to add it if there is no one if else Operation
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. Add resource release in remove () function
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
........................................................
}
Method 2:
If there is no search for the keyword "DEVICE_ATTR" in the driver file to be added, such as adding the control interface for opening and closing the audio power amplifier:
1. Add key header files:
#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. Define global variables and open and closed interfaces and organize attribute arrays:
// 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__);
// Timing of power amplifier opening
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__);
// Timing of power amplifier closing
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. Add the registration of file system attribute interface in probe () function:
There is no need to initialize the power amplifier at the time of registration, so the sdm660_cdc () function does not have an sdm660_cdc-
>
spk_pa_gpio (GPIO63), only the request was manipulated. For specific request operation, please refer to: EAR of audio section of
8953 and audio section of Speaker output sound configuration
vendor/qcom/opensource/audio-kernel/asoc/codecs/sdm660_cdc/msm-analog-cdc. c file operation
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; // That defines the equipment tree species IO The slogan is obtained
spk_pa_kobj = kobject_create_and_add("spk_pa", NULL); // Create /sys/spk_pa/ Directory
ret = sysfs_create_group(spk_pa_kobj, &apkpa_attr_group); // Create /sys/class/spk_pa/spkpaon Node
if (ret)
dev_err(&pdev->dev,"%s:sysfs_create_group failed with error\n",__func__);
//end zhaojr add
....................................
4. Release resources in remove function
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 // Release resources
gpio_free(sdm660_cdc->spk_pa_gpio);
kobject_put(spk_pa_kobj); // Key function
sysfs_remove_group(spk_pa_kobj, &apkpa_attr_group); // Key function
//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;
}
Summarize