On Sat, Nov 3, 2012 at 8:26 AM, Wolfgang Denk wd@denx.de wrote:
Dear Simon Glass,
In message 1351902453-27956-16-git-send-email-sjg@chromium.org you wrote:
From: Vadim Bendebury vbendeb@chromium.org
Provide u-boot console functions to access IO space registers. A no thrills implementation, accessing one register at a time.
For example: boot > iod 80 0080: 00000094 boot > iod.w 80 0080: 0094 boot > iod.b 80 0080: 94 boot > iow.b 0x80 12 boot > iod 0x80 0080: 00000012
What are the exact use cases where this is necessary, i. e. where plain md / mw does not work?
Wolfgang,
the x86 architecture defines this different kind of address space, device IO, in addition to memory address space. This is a remnant of the days when address lines were sparse.
On typical x86 systems devices are accessed through this device IO space, and this patch adds a command which allows the operator to read and write device registers on such systems.
Cheers, /vb
Best regards,
Wolfgang Denk
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