I have writen a driver that implements a simple platform device. It basically reads I/O Mapped registers using request_mem_region()/ioremap()/release_mem_region() and export its contents to user space using sysfs. This driver is used for debugging purposes. The problem takes place when I try to read these registers when the corresponding driver, that uses these I/O mapped registers, is loaded. In other words, I cannot request the memory region, it return a "device busy" error. If I disable the the request_/release_mem_region() it works. One questions arises from it: Is there a way to read these I/O mapped registers without bypassing the request_/release_mem_region() functions ? Linux Kernel version: 3.10.54 on ARMv7 Best regards, Rafael. -- "It is not that I am so smart, it is just that I stay with problems longer." --Albert Einstein