platfrom的probe的详解
平台设备的注册
platform_add_devices(ldd6410_devices, ARRAY_SIZE(ldd6410_devices)); //这是bsp中添加所有的设备
-->
platform_device_register(devs[i]);//注册平台设备
--->
platform_device_add(pdev);将平台设备加入到platform_bus中
--->
device_add(&pdev->dev);
平台驱动的注册
platform_driver_register(&gpio_led_driver)
---->
driver_register(&drv->driver);
---->
bus_add_driver(drv); //添加驱动到总线
--->
driver_attach(drv);//为驱动寻找相应的设备
---->
__driver_attach()
---->
driver_probe_device(drv, dev);
--->
really_probe(dev, drv);
static int __init XXX_init(void)
{
return platform_driver_register(&XXX_driver); //注册平台驱动
}
int driver_attach(struct device_driver *drv)
{
return bus_for_each_dev(drv->bus, NULL, drv, __driver_attach); //遍历设备总线寻找驱动
}
static int __driver_attach(struct device *dev, void *data)
{
struct device_driver *drv = data;
/*
* Lock device and try to bind to it. We drop the error
* here and always return 0, because we need to keep trying
* to bind to devices and some drivers will return an error
* simply if it didn't support the device.
*
* driver_probe_device() will spit a warning if there
* is an error.
*/
if (drv->bus->match && !drv->bus->match(dev, drv)) //通过match判断驱动和设备是否匹配，这里通过比较dev和drv中的设备名来判断，所以设备名需要唯一
return 0;
if (dev->parent) /* Needed for USB */
down(&dev->parent->sem);
down(&dev->sem);
if (!dev->driver)
driver_probe_device(drv, dev); // 驱动和设备绑定
up(&dev->sem);
if (dev->parent)
up(&dev->parent->sem);
return 0;
}
static int really_probe(struct device *dev, struct device_driver *drv)
{
int ret = 0;
atomic_inc(&probe_count);
pr_debug("bus: '%s': %s: probing driver %s with device %s\n",
drv->bus->name, __func__, drv->name, dev->bus_id);
WARN_ON(!list_empty(&dev->devres_head));
dev->driver = drv;
if (driver_sysfs_add(dev)) {
printk(KERN_ERR "%s: driver_sysfs_add(%s) failed\n",
__func__, dev->bus_id);
goto probe_failed;
}
if (dev->bus->probe) {
ret = dev->bus->probe(dev);
if (ret)
goto probe_failed;
} else if (drv->probe) {
ret = drv->probe(dev); //这里才真正调用了驱动的probe
if (ret)
goto probe_failed;
}
driver_bound(dev);
ret = 1;
pr_debug("bus: '%s': %s: bound device %s to driver %s\n",
drv->bus->name, __func__, dev->bus_id, drv->name);
goto done;
probe_failed:
devres_release_all(dev);
driver_sysfs_remove(dev);
dev->driver = NULL;
if (ret != -ENODEV && ret != -ENXIO) {
/* driver matched but the probe failed */
printk(KERN_WARNING
"%s: probe of %s failed with error %d\n",
drv->name, dev->bus_id, ret);
}
/*
* Ignore errors returned by ->probe so that the next driver can try
* its luck.
*/
ret = 0;
done:
atomic_dec(&probe_count);
wake_up(&probe_waitqueue);
return ret;
}