Linux驱动 probe函数调用

参考：

http://blog.chinaunix.net/space.php?uid=15887868&do=blog&id=2758294

http://www.cnblogs.com/hoys/archive/2011/04/01/2002299.html
1，driver_register把驱动注册到总线 

/** * driver_register - register driver with bus * @drv: driver to register * We pass off most of the work to the bus_add_driver() call, * since most of the things we have to do deal with the bus * structures. */int driver_register(struct device_driver *drv){……………………if ((drv->bus->probe && drv->probe) ||    (drv->bus->remove && drv->remove) ||    (drv->bus->shutdown && drv->shutdown))ret = bus_add_driver(drv);//把drv驱动，注册到总线……………………}

2，驱动注册到总线的实现函数

/** * bus_add_driver - Add a driver to the bus.        -----在总线上加入一个驱动 * @drv: driver. */int bus_add_driver(struct device_driver *drv){………………if (drv->bus->p->drivers_autoprobe) {error = driver_attach(drv);      //驱动的匹配函数………………}

3，driver_attach()

/** * driver_attach - try to bind driver to devices. * @drv: driver. * * Walk the list of devices that the bus has on it and try to * match the driver with each one.  If driver_probe_device() * returns 0 and the @dev->driver is set, we've found a * compatible pair. */int driver_attach(struct device_driver *drv){return bus_for_each_dev(drv->bus, NULL, drv, __driver_attach);//注意这里的__driver_attach}EXPORT_SYMBOL_GPL(driver_attach);

上面真正起作用的是__driver_attach：

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 (!driver_match_device(drv, dev))return 0;if (dev->parent)/* Needed for USB */device_lock(dev->parent);device_lock(dev);if (!dev->driver)driver_probe_device(drv, dev);//看下这个函数的实现过程device_unlock(dev);if (dev->parent)device_unlock(dev->parent);return 0;}int driver_probe_device(structdevice_driver *drv, struct device *dev){...//1.先是判断bus是否match：if (drv->bus->match && !drv->bus->match(dev, drv))   goto done;//2.再具体执行probe：ret = really_probe(dev, drv);...}

4,really_probe是我们真正要找的函数

static int really_probe(struct device *dev, struct device_driver *drv){……………………//1.先是调用的驱动所属总线的probe函数：if (dev->bus->probe) {ret = dev->bus->probe(dev);if (ret)goto probe_failed;} //2.再调用的驱动中的probe函数：else if (drv->probe) {ret = drv->probe(dev);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_name(dev), drv->name);//这个信息可以看到我们注册的总 驱动、设备和总线  信息goto done;………………}

5.drv->bus->match(dev, drv)

driver_probe_device(struct device_driver *drv, struct device *dev)会通过drv->bus->match()来匹配PCIE设备与相应的设备驱动。对于内核为2.6.27的bus驱动“pci_express”来说，是通过调用pcie_port_bus_match()实现驱动match的。

 

static int pcie_port_bus_match(struct device *dev, struct device_driver *drv){struct pcie_device *pciedev;struct pcie_port_service_driver *driver;if (drv->bus != &pcie_port_bus_type || dev->bus != &pcie_port_bus_type)return 0;pciedev = to_pcie_device(dev);driver = to_service_driver(drv);if (   (driver->id_table->vendor != PCI_ANY_ID && driver->id_table->vendor != pciedev->id.vendor) ||       (driver->id_table->device != PCI_ANY_ID &&driver->id_table->device != pciedev->id.device) ||       (driver->id_table->port_type != PCIE_ANY_PORT &&driver->id_table->port_type != pciedev->id.port_type) ||driver->id_table->service_type != pciedev->id.service_type )return 0;          // driver与pciedev的id_table匹配成功，才match成功；return 1;}

// id_table的结构定义如下，match时只关注vendor,device,port_type,service_typestruct pcie_port_service_id {__u32 vendor, device;/* Vendor and device ID or PCI_ANY_ID*/__u32 subvendor, subdevice;/* Subsystem ID's or PCI_ANY_ID */__u32 class, class_mask;/* (class,subclass,prog-if) triplet */__u32 port_type, service_type;/* Port Entity */kernel_ulong_t driver_data;};

 

打印出的驱动设备信息如：

………………

[    0.588087] bus: 'platform': really_probe: bound device power.0to driverpower  //总线：platform  设备：power.0  驱动：power
[    0.661226] bus: 'platform': really_probe: bound device s3c24xx-pwm.0 to driver s3c24xx-pwm
[    0.678552] bus: 'platform': really_probe: bound device s3c24xx-pwm.1 to driver s3c24xx-pwm
[    0.695971] bus: 'platform': really_probe: bound device s3c24xx-pwm.2 to driver s3c24xx-pwm
[    0.713389 bus: 'platform': really_probe: bound device s3c24xx-pwm.3 to driver
……………………