接前一篇文章Linux网络驱动之Fixed-Link17本文内容参考linux phy fixed-link-CSDN博客linux phy处理流程一:探测phy设备_phy link过程-CSDN博客linux phy处理流程三:fixed-link处理-CSDN博客ARM与交换芯片mac_to_mac固定模式总结_mac to mac-CSDN博客rk3399 mac to mac 连接switch - tccxy - 博客园特此致谢三、深入了解前边用了几个回目的篇幅讲解了of_mdiobus_register和mdiobus_register函数的区别。本回要回归到当初引出这段讲解的地方参见Linux网络驱动之Fixed-Link13-CSDN博客之前先围绕着第3个函数调用ret mdiobus_register(fmb-mii_bus);进行了深入解析。现在要拉回来讲解第1个函数调用pdev platform_device_register_simple(Fixed MDIO bus, 0, NULL, 0); if (IS_ERR(pdev)) return PTR_ERR(pdev);platform_device_register_simple函数是一个内联函数在kernel/linux-5.10-origin/include/linux/platform_device.h中代码如下/** * platform_device_register_simple - add a platform-level device and its resources * name: base name of the device were adding * id: instance id * res: set of resources that needs to be allocated for the device * num: number of resources * * This function creates a simple platform device that requires minimal * resource and memory management. Canned release function freeing memory * allocated for the device allows drivers using such devices to be * unloaded without waiting for the last reference to the device to be * dropped. * * This interface is primarily intended for use with legacy drivers which * probe hardware directly. Because such drivers create sysfs device nodes * themselves, rather than letting system infrastructure handle such device * enumeration tasks, they dont fully conform to the Linux driver model. * In particular, when such drivers are built as modules, they cant be * hotplugged. * * Returns struct platform_device pointer on success, or ERR_PTR() on error. */ static inline struct platform_device *platform_device_register_simple( const char *name, int id, const struct resource *res, unsigned int num) { return platform_device_register_resndata(NULL, name, id, res, num, NULL, 0); }platform_device_register_simple函数说明如下函数原型static inline struct platform_device *platform_device_register_simple(const char *name, int id,const struct resource *res, unsigned int num);函数功能添加平台级设备及其资源。此函数创建了一个需要最少资源和内存管理的简单平台设备。释放为设备所分配内存的封装函数允许使用此类设备的驱动程序被卸载而无需等待删除对设备的最后一次引用。此接口主要用于直接探测硬件的传统驱动程序。因为这样的驱动程序自己创建sysfs设备结点而不是让系统基础设施处理这样的设备枚举任务因此它们并不完全符合Linux驱动程序模型。特别地当这些驱动程序被构建编译为模块时它们不能被“热插拔”。参数说明name要添加的设备的基本名称id实例idres需要为设备分配的资源集num资源的数量返回值成功返回指向struct platform_device的指针失败返回ERR_PTR。对照着上边实际调用进行理解pdev platform_device_register_simple(Fixed MDIO bus, 0, NULL, 0); if (IS_ERR(pdev)) return PTR_ERR(pdev);要添加的平台级设备名称为Fixed MDIO bus实例id为0不需要分配资源集资源的数量为0。真正完成工作的是platform_device_register_resndata函数。它也在include/linux/platform_device.h中就在上边代码如下/** * platform_device_register_resndata - add a platform-level device with * resources and platform-specific data * * parent: parent device for the device were adding * name: base name of the device were adding * id: instance id * res: set of resources that needs to be allocated for the device * num: number of resources * data: platform specific data for this platform device * size: size of platform specific data * * Returns struct platform_device pointer on success, or ERR_PTR() on error. */ static inline struct platform_device *platform_device_register_resndata( struct device *parent, const char *name, int id, const struct resource *res, unsigned int num, const void *data, size_t size) { struct platform_device_info pdevinfo { .parent parent, .name name, .id id, .res res, .num_res num, .data data, .size_data size, .dma_mask 0, }; return platform_device_register_full(pdevinfo); }对于该函数的解析请看下回。
