驱动报告uevent示例

#include <linux/module.h>
#include <linux/init.h>
#include <linux/gpio.h>
#include <linux/slab.h>
#include <linux/kobject.h>
#include <linux/sysfs.h>
#include <linux/kernel.h>
#include <linux/interrupt.h>
#include <linux/platform_device.h>
#include <asm/irq.h>
#include <mach/fp8102_det.h>

int irqnum = 0;
struct uevent_platform_data* uinfo = NULL;
static struct kset *uevent_kset = NULL;
static struct work_struct uevent_wq;

static char charged_str[] = "fully-charged";
static char charging_str[] = "charging";

struct uevent_obj {
struct kobject kobj;
int val;
};
struct uevent_obj *uobj;

struct uevent_attribute {
struct attribute attr;
ssize_t (*show)(struct uenent_obj *uobj, struct attribute *attr, char *buf);
ssize_t (*store)(struct uevent_obj *uobj, struct attribute *attr,
const char *buf, size_t count);
};

static ssize_t uevent_attr_show(struct kobject *kobj,
struct attribute *attr,
char *buf)
{
ssize_t count;
if (gpio_get_value(uinfo->detect_pin) ^ uinfo->charge_active_low)
count = sprintf(buf, "%s\n", charging_str);
else
count = sprintf(buf, "%s\n", charged_str);
return  count;
}

static ssize_t uevent_attr_store(struct kobject *kobj,
struct attribute *attr,
const char *buf, size_t len)
{
return 0;
}

static const struct sysfs_ops uevent_sysfs_ops = {
.show = uevent_attr_show,
.store = uevent_attr_store,
};

static void uevent_release(struct kobject *kobj)
{
kfree(uobj);
}

static ssize_t uevent_show(struct uevent_obj *uevent_obj, struct attribute *attr,
char *buf)
{
/*do nothing*/
return  0;
}

static ssize_t uevent_store(struct uvent_obj *uevent_obj, struct attribute *attr,
const char *buf, size_t count)
{
/*do nothing*/
return  0;
}

static struct uevent_attribute fp8102_uevent_attr =
__ATTR(uevent, 0666, uevent_show, uevent_store);

static struct attribute *uevent_default_attrs[] = {
&fp8102_uevent_attr.attr,
NULL,
};

static struct kobj_type uevent_ktype = {
.sysfs_ops = &uevent_sysfs_ops,
.release = uevent_release,
.default_attrs = uevent_default_attrs,
};

static void destroy_uevent_obj(struct uevent_obj *ub)
{
kobject_put(&ub->kobj);
kfree(&ub->kobj);
}

void uevent_do_work(struct work_struct *work)
{
char *msg[] = {NULL, NULL};
if (gpio_get_value(uinfo->detect_pin) ^ uinfo->charge_active_low)
msg[0] = charging_str;
else
msg[0] = charged_str;

kobject_uevent_env(&uobj->kobj, KOBJ_CHANGE, msg);
}

static irqreturn_t interrupt_isr(int irq, void *data)
{
schedule_work(&uevent_wq);
return IRQ_HANDLED;
}

static int fp8102_det_probe( struct platform_device *pdev)
{
int ret = 0;
uinfo = pdev->dev.platform_data;
if(!uinfo){
printk("get uevent pdata failed \n");
return -EINVAL;
}

uevent_kset = kset_create_and_add("uevent_report", NULL, kernel_kobj);
if (!uevent_kset){
return -ENOMEM;
}
uobj = kzalloc(sizeof(*uobj), GFP_KERNEL);
if (!uobj){
goto kset_error;
}

INIT_WORK(&uevent_wq, uevent_do_work);

uobj->kobj.kset = uevent_kset;
ret = kobject_init_and_add(&uobj->kobj, &uevent_ktype, NULL, "%s", "uevent_report");
if (ret){
goto uevent_error;
}

ret = gpio_request(uinfo->detect_pin, "uevent_report");
if (ret){
printk("gpio reuest for uevent report failed\n");
goto uevent_error;
}

irqnum = gpio_to_irq(uinfo->detect_pin);
if (request_irq(irqnum, interrupt_isr, IRQF_TRIGGER_RISING | IRQF_TRIGGER_FALLING, "uevent_report", NULL)) {
printk(KERN_ERR "uevent.c: Can't allocate irq %d\n", irqnum);
goto gpio_error;
}

return 0;

gpio_error:
gpio_free(uinfo->detect_pin);
uevent_error:
destroy_uevent_obj(uobj);
kset_error:
kset_unregister(uevent_kset);
return -EINVAL;
}

static int fp8102_det_remove(struct platform_device *dev)
{
destroy_uevent_obj(uobj);
kset_unregister(uevent_kset);
free_irq(irqnum, NULL);
gpio_free(uinfo->detect_pin);
return 0;
}

static struct platform_driver fp8102_det_driver = {
.driver = {
.name = "fp8102_det",
.owner = THIS_MODULE,
},
.probe = fp8102_det_probe,
.remove = fp8102_det_remove,
};

static int __init fp8102_det_init(void)
{
return platform_driver_register(&fp8102_det_driver);
}

static void __exit fp8102_det_exit(void)
{
platform_driver_unregister(&fp8102_det_driver);
}

module_init(fp8102_det_init);
module_exit(fp8102_det_exit);

MODULE_DESCRIPTION("fp8102 charge status report");
MODULE_LICENSE("GPL v2");
MODULE_AUTHOR("Bing");

代码功能:

实现底层向上层报告uevent的功能,比如说底层有个按键按下或者电池充电状态发生改变,而应用程序需要获取这一事件,我们就可以在按键按下的时候发出uevent事件.

细节问题:

uevent必须依附一个kobj;

底半部最好用工作队列,而不是软中断.