27 lines
1.2 KiB
ReStructuredText
27 lines
1.2 KiB
ReStructuredText
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==============
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DEVMEM Drivers
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==============
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The `devmem` driver provides an interface for accessing memory-mapped
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I/O in an embedded system. This driver allows for reading, writing, and
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memory mapping of specific memory regions or device registers.
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``read()``: This function reads data from the memory-mapped I/O address
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space into the buffer provided by the caller. The first byte read
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corresponds to the address specified by the device's "current memory
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address". The addresses for subsequent bytes depend on the auto-increment
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behavior of the specific device.
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``write()``: This function transfers data from the provided data buffer by
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the caller to the memory-mapped I/O address space. The first byte written
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corresponds to the address specified by the device's "current memory address".
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``mmap()``: The `mmap()` function provides a mechanism to map a device's
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memory region into the user space, allowing direct access to device
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registers or memory regions. The mapped region can be accessed using
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normal memory operations.
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The function requires a base address and size for the memory region
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to be mapped. If successful, it returns a pointer to the mapped region.
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If mapping fails, it returns `EINVAL` and `errno` is set appropriately.
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