旧版本的platform_device和platform_driver和新版本中的操作解释
旧版本中
一个linux设备的驱动和设备一般是挂载到一种总线上，系统中对于一些不能依附于总线的设备，linux设计出虚拟总线，platform设备总线。旧版本中，通过platform_device和platform_driver进行设备和驱动的注册，这个过程中，设备和驱动的名称必须一致，才能保证在程序启动的过程中，驱动才能匹配到总线上的设备。
新的版本中
只需要进行设备驱动的注册，而设备的注册通过DTS进行，在DTS中通过.compatible属性设置设备名称。当linux启动时通过dts就会将设备加载到platform设备总线上。当通过platform_driver_register函数进行注册时，内部就会调用一个总线注册的结构体，在结构体中有设备和驱动名称匹配函数，即将设备和驱动进行绑定。
#defineplatform_driver_register(drv) \
__platform_driver_register(drv, THIS_MODULE)
int __platform_driver_register(struct platform_driver *drv,
struct module *owner)
{
drv->driver.owner = owner;
drv->driver.bus = &platform_bus_type;
if (drv->probe)
drv->driver.probe = platform_drv_probe;
if (drv->remove)
drv->driver.remove = platform_drv_remove;
if (drv->shutdown)
drv->driver.shutdown = platform_drv_shutdown;
return driver_register(&drv->driver);
}
struct bus_type platform_bus_type = {
.name = "platform",
.dev_groups = platform_dev_groups,
.match = platform_match,
.uevent = platform_uevent,
.pm = &platform_dev_pm_ops,
};
static int platform_match(struct device *dev, struct device_driver *drv)
{
struct platform_device *pdev = to_platform_device(dev);
struct platform_driver *pdrv = to_platform_driver(drv);
/* Attempt an OF style match first */
if (of_driver_match_device(dev, drv))
return 1;
/* Then try ACPI style match */
if (acpi_driver_match_device(dev, drv))
return 1;
/* Then try to match against the id table */
if (pdrv->id_table)
return platform_match_id(pdrv->id_table, pdev) != NULL;
/* fall-back to driver name match */
return (strcmp(pdev->name, drv->name) == 0);
}
static const struct platform_device_id *platform_match_id(
const struct platform_device_id *id,
struct platform_device *pdev)
{
while (id->name[0]) {
if (strcmp(pdev->name, id->name) == 0) {
pdev->id_entry = id;
return id;
}
id++;
}
return NULL;
}
static inline int of_driver_match_device(struct device *dev,
const struct device_driver *drv)
{
return of_match_device(drv->of_match_table, dev) != NULL;
}
const struct of_device_id *of_match_device(const struct of_device_id *matches,
const struct device *dev)
{
if ((!matches) || (!dev->of_node))
return NULL;
return of_match_node(matches, dev->of_node);
}
const struct of_device_id *of_match_node(const struct of_device_id *matches,
const struct device_node *node)
{
const struct of_device_id *match;
unsigned long flags;
raw_spin_lock_irqsave(&devtree_lock, flags);
match = __of_match_node(matches, node);
raw_spin_unlock_irqrestore(&devtree_lock, flags);
return match;
}
const struct of_device_id *__of_match_node(const struct of_device_id *matches,
const struct device_node *node)
{
if (!matches)
return NULL;
while (matches->name[0] || matches->type[0] || matches->compatible[0]) {
int match = 1;
if (matches->name[0])
match &= node->name
&& !strcmp(matches->name, node->name);
if (matches->type[0])
match &= node->type
&& !strcmp(matches->type, node->type);
if (matches->compatible[0])
match &= __of_device_is_compatible(node,
matches->compatible);
if (match)
return matches;
matches++;
}
return NULL;
}
在platform_当匹配函数完成后再调用platform_driver中自己定义的probe函数