platform_driver_register，什么时候调用PROBE函数 注册后如何找到驱动匹配的设备

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kernel_init中do_basic_setup()->driver_init()->platform_bus_init()->…初始化platform bus(虚拟总线)

设备向内核注册的时候platform_device_register()->platform_device_add()->…内核把设备挂在虚拟的platform bus下

驱动注册的时候platform_driver_register()->driver_register()->bus_add_driver()->driver_attach()->bus_for_each_dev()

对每个挂在虚拟的platform bus的设备作__driver_attach()->driver_probe_device()->drv->bus->match()==platform_match()->比较strncmp(pdev->name, drv->name, BUS_ID_SIZE)，

如果相符就调用platform_drv_probe()->driver->probe()，如果probe成功则绑定该设备到该驱动.

kernel/init/main.c 

static int __init kernel_init(void * unused)

{

/*

 * Wait until kthreadd is all set-up.

 */

wait_for_completion(&kthreadd_done);

/*

 * init can allocate pages on any node

 */

set_mems_allowed(node_states[N_HIGH_MEMORY]);

/*

 * init can run on any cpu.

 */

set_cpus_allowed_ptr(current, cpu_all_mask);

cad_pid = task_pid(current);

smp_prepare_cpus(setup_max_cpus);

do_pre_smp_initcalls();

lockup_detector_init();

smp_init();

sched_init_smp();

do_basic_setup();

/* Open the /dev/console on the rootfs, this should never fail */

if (sys_open((const char __user *) “/dev/console”, O_RDWR, 0) < 0)

printk(KERN_WARNING “Warning: unable to open an initial console.\n”);

(void) sys_dup(0);

(void) sys_dup(0);

/*

 * check if there is an early userspace init.  If yes, let it do all

 * the work

 */

if (!ramdisk_execute_command)

ramdisk_execute_command = “/init”;

if (sys_access((const char __user *) ramdisk_execute_command, 0) != 0) {

ramdisk_execute_command = NULL;

prepare_namespace();

}

/*

 * Ok, we have completed the initial bootup, and

 * we’re essentially up and running. Get rid of the

 * initmem segments and start the user-mode stuff..

 */

init_post();

return 0;

}

static void __init do_basic_setup(void)

{

cpuset_init_smp();

usermodehelper_init();

init_tmpfs();

driver_init();

init_irq_proc();

do_ctors();

do_initcalls();

}

kernel/drivers/base/init.c

void __init driver_init(void)

{

/* These are the core pieces */

devtmpfs_init();

devices_init();

buses_init();

classes_init();

firmware_init();

hypervisor_init();

/* These are also core pieces, but must come after the

 * core core pieces.

 */

platform_bus_init();

system_bus_init();

cpu_dev_init();

memory_dev_init();

}

kernel/drivers/base/platform.c

注册虚拟总线

int __init platform_bus_init(void)

{

int error;

early_platform_cleanup();

error = device_register(&platform_bus);

if (error)

return error;

error =  bus_register(&platform_bus_type);

if (error)

device_unregister(&platform_bus);

return error;

}

kernel/drivers/base/platform.c

int platform_device_register(struct platform_device *pdev)

{

device_initialize(&pdev->dev);

return platform_device_add(pdev);

}

kernel/drivers/base/platform.c

int platform_driver_register(struct platform_driver *drv)

{

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);

}

kernel/drivers/base/driver.c

int driver_register(struct device_driver *drv)

{

int ret;

struct device_driver *other;

BUG_ON(!drv->bus->p);

if ((drv->bus->probe && drv->probe) ||

    (drv->bus->remove && drv->remove) ||

    (drv->bus->shutdown && drv->shutdown))

printk(KERN_WARNING “Driver ‘%s’ needs updating – please use “

“bus_type methods\n”, drv->name);

other = driver_find(drv->name, drv->bus);

if (other) {

put_driver(other);

printk(KERN_ERR “Error: Driver ‘%s’ is already registered, “

“aborting…\n”, drv->name);

return -EBUSY;

}

ret = bus_add_driver(drv);

if (ret)

return ret;

ret = driver_add_groups(drv, drv->groups);

if (ret)

bus_remove_driver(drv);

return ret;

}

kernel/drivers/base/bus.c

int bus_add_driver(struct device_driver *drv)

{

struct bus_type *bus;

struct driver_private *priv;

int error = 0;

bus = bus_get(drv->bus);

if (!bus)

return -EINVAL;

pr_debug(“bus: ‘%s’: add driver %s\n”, bus->name, drv->name);

priv = kzalloc(sizeof(*priv), GFP_KERNEL);

if (!priv) {

error = -ENOMEM;

goto out_put_bus;

}

klist_init(&priv->klist_devices, NULL, NULL);

priv->driver = drv;

drv->p = priv;

priv->kobj.kset = bus->p->drivers_kset;

error = kobject_init_and_add(&priv->kobj, &driver_ktype, NULL,

     “%s”, drv->name);

if (error)

goto out_unregister;

if (drv->bus->p->drivers_autoprobe) {

error = driver_attach(drv);

if (error)

goto out_unregister;

}

klist_add_tail(&priv->knode_bus, &bus->p->klist_drivers);

module_add_driver(drv->owner, drv);

error = driver_create_file(drv, &driver_attr_uevent);

if (error) {

printk(KERN_ERR “%s: uevent attr (%s) failed\n”,

__func__, drv->name);

}

error = driver_add_attrs(bus, drv);

if (error) {

/* How the hell do we get out of this pickle? Give up */

printk(KERN_ERR “%s: driver_add_attrs(%s) failed\n”,

__func__, drv->name);

}

if (!drv->suppress_bind_attrs) {

error = add_bind_files(drv);

if (error) {

/* Ditto */

printk(KERN_ERR “%s: add_bind_files(%s) failed\n”,

__func__, drv->name);

}

}

kobject_uevent(&priv->kobj, KOBJ_ADD);

return 0;

out_unregister:

kobject_put(&priv->kobj);

kfree(drv->p);

drv->p = NULL;

out_put_bus:

bus_put(bus);

return error;

}

kernel/drivers/base/Dd.c

int driver_attach(struct device_driver *drv)

{

return bus_for_each_dev(drv->bus, NULL, drv, __driver_attach);

}

EXPORT_SYMBOL_GPL(driver_attach);

kernel/drivers/base/bus.c

int bus_for_each_dev(struct bus_type *bus, struct device *start,

     void *data, int (*fn)(struct device *, void *))

{

struct klist_iter i;

struct device *dev;

int error = 0;

if (!bus)

return -EINVAL;

klist_iter_init_node(&bus->p->klist_devices, &i,

     (start ? &start->p->knode_bus : NULL));

while ((dev = next_device(&i)) && !error)

error = fn(dev, data);

klist_iter_exit(&i);

return error;

}

EXPORT_SYMBOL_GPL(bus_for_each_dev);