hi, Olivier:
Thanks for the quick response!
Your explaination is clear enought for me!
best wishes,
发件人: Olivier Martin [mailto:olivier.mar...@arm.com]
发送时间:2012年8月3日 16:54
收件人: edk2-devel@lists.sourceforge.net
主题: Re: [edk2] ARM EMBEDDED_DEVICE_PROTOCOL and_EMBEDDED_EXTERNAL_DEVICE
Hi Nicolas,
Looking at which modules use those protocols, they look as two different
protocols.
EMBEDDED_EXTERNAL_DEVICE: the only module today that implements this protocol
is the OMAP3 PMIC.
A reason to use this driver could be for instance you write a driver that
depends on a standardized external device but not defined by the UEFI spec (I
do not have one in mind) but you do not know where this external device is
(case the device is memory mapped), this protocol allow to access this external
device from your device driver in a platform independent way.
But maybe this driver would need an additional parameter to identify the type
of external device (the EFI Device Path will not help you to solve this
limitation if the external device has not any EFI Device Path Node
representation in the UEFI spec – probably all the External Device will have be
VenHw(...) device path)..
EMBEDDED_DEVICE_PROTOCOL: one ‘limitation’ of most embedded system in
comparison to PC system is most of their controllers are located at a different
location in the memory map and they are no attached to enumerable bus (such as
PCI). So it is quite difficult to know which device are present on a specific
platform.
This protocol is a tentative to get a solution to this limitation.
Note: These two protocols are not ARM specific. You should consider everything
under EmbeddedPkg as architecture independent.
Let me know if the explanation is clear enough. If it is I will copy it to the
EmbeddedPkg Tianocore wikipage.
Kind Regards,
Olivier
From: nicolas [mailto:nicolas1...@163.com]
Sent: 03 August 2012 09:28
To: edk2-devel@lists.sourceforge.net
Subject: [edk2] ARM EMBEDDED_DEVICE_PROTOCOL and _EMBEDDED_EXTERNAL_DEVICE
hi, experts:
i found 2 protocols definitions in EmbeddedPkg\Include\Protocol directory:
_EMBEDDED_EXTERNAL_DEVICE and EMBEDDED_DEVICE_PROTOCOL.
so, my question is:
Which component on an ARM board could produce _EMBEDDED_EXTERNAL_DEVICE
protocol?
Which component on an ARM board could produce EMBEDDED_DEVICE_PROTOCOL?
Is there some standards?
best wishes
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