sysfs接口说明

来源：互联网发布：windows刷mac os 编辑：程序博客网时间：2024/05/23 10:26

以gpiolib.c文件里边的sysfs接口为例。

device attr定义方式有好几种，

1. 下面是通过DEVICE_ATTR宏定义的方式

static const DEVICE_ATTR(active_low, 0644,
gpio_active_low_show, gpio_active_low_store);

static const struct attribute *gpio_attrs[] = {
&dev_attr_value.attr,
&dev_attr_active_low.attr,
NULL,
};

static const struct attribute_group gpio_attr_group = {
.attrs = (struct attribute **) gpio_attrs,
};

sysfs_create_group(&dev->kobj, &gpio_attr_group);
//在kobject对应的目录下生成一组文件

2. 下面是通过power_attr()定义的方式

#define power_attr(_name) \
static struct kobj_attribute _name##_attr = {\
.attr= { \
.name = __stringify(_name),\
.mode = 0644,\
},\
.show= _name##_show, \
.store= _name##_store, \
}

static ssize_t pm_async_show(struct kobject *kobj, struct kobj_attribute *attr,
   char *buf)
{
return sprintf(buf, "%d\n", pm_async_enabled);
}

static ssize_t pm_async_store(struct kobject *kobj, struct kobj_attribute *attr,
   const char *buf, size_t n)
{
unsigned long val;
if (strict_strtoul(buf, 10, &val))
return -EINVAL;
if (val > 1)
return -EINVAL;
pm_async_enabled = val;
return n;
}

power_attr(pm_async);
static struct attribute *g[] = {
    .............
&pm_async_attr.attr,
    .............
};

static struct attribute_group attr_group = {
      .attrs = g,
};

sysfs_create_group(power_kobj, &attr_group);

0 0