read() via USB bus

Oliver Neukum oneukum at
Mon Aug 9 04:15:29 EDT 2021

On 09.08.21 09:58, Muni Sekhar wrote:
> Hi all,
> PCIe memory mapped registers can be read via readb(), readw(), readl()
> kernel API's. Similarly what are the kernel API to read the device
> registers via USB bus


I am afraid this is based on a fundamental misunderstanding on how
USB works. It is based on passing messages, not reading and writing

USB devices are primarily based on endpoints, not registers. A literal
answer to your question would point you to the clear/set/get_feature
standard requests of chapter 9 of the specification, but that really
will not help you, as you are making assumption that fundamentally
do not apply.

I hope this list stays friendly to newcomers and we will answer
specific questions, but at this point I must advise you to first
read an introductory book.


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