Linux macro definition request_mem_region ()

Linux macro definition request_mem_region () -- Linux general technology-Linux programming and kernel information. The following is a detailed description. Based on the I/O Region operation function _ XXX_region (), Linux defines three macros for operating I/O memory resources in the header file include/linux/ioport. h:

① Request_mem_region () Macro, requesting allocation of specified I/O memory resources.

② Check _ mem_region () macro to check whether the specified I/O memory resources are occupied.

③ Release _ mem_region () macro to release the specified I/O memory resources.

The three macros are defined as follows:

# Define request_mem_region (start, n, name)
_ Request_region (& iomem_resource, (start), (n), (name ))
# Define check_mem_region (start, n)
_ Check_region (& iomem_resource, (start), (n ))
# Define release_mem_region (start, n)
_ Release_region (& iomem_resource, (start), (n ))

Here, the start parameter is the starting physical address of the I/O memory resource (the physical address in the CPU's RAM physical address space), and the parameter n specifies the size of the I/O memory resource.