Why is there `gpio_request` instead of` request_region` in the raspberry pi driver?

Question

In the LDD3 book, if one driver wants to control the CPU pins, it must call a function request_region()to declare port usage.

When I want to implement a simple driver module on my Raspberry Pi, however, what I found in this example , the port request is implemented using a function gpio_request(),

Why and when do we need to use gpio_request()instead request_region()? And what are the distinctive goals for these two functions.

BTW: I searched the LDD3 page for page, but I cannot find any clues about GPIO... why there are no introductions for GPIO? Is this due to kernel version 2.6?

Answer 1

In the LDD3 book, if one driver wants to control the contacts of the CPU, it must call the request_region () function to declare the use of ports.

Firstly, the word "port" is ambiguous and requires context. The port can refer to a physical connector (for example, a USB port) or a logical connection (for example, a TCP port).

Your understanding of request_region () is incorrect. This procedure is for managing the I / O address space. Your question is tagged with a tag raspberry-p1that uses an ARM processor and does not have an I / O address space for management. ARM processors use device registers with memory. You would use request_mem_region () in the device driver for the memory addresses of this block of peripheral registers.

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