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From: "Philippe Mathieu-Daudé" <philmd@redhat.com>
To: Stefan Berger <stefanb@linux.ibm.com>,
	qemu-devel <qemu-devel@nongnu.org>,
	Eric Auger <eric.auger@redhat.com>
Cc: "Marc-André Lureau" <marcandre.lureau@redhat.com>,
	"David Safford" <safford@us.ibm.com>
Subject: What is TYPE_TPM_TIS_ISA? (Not an ISA Device)
Date: Tue, 21 Jul 2020 18:02:56 +0200	[thread overview]
Message-ID: <8f5a171a-59db-f5d1-477c-1ddf7af45da7@redhat.com> (raw)

Hi Stefan,

I'm trying to understand what is modelling the
TYPE_TPM_TIS_ISA device.

It inherits from TYPE_ISA_DEVICE, so I expected
to see an ISA device, but then I noticed:

1/ it doesn't use the ISA I/O space, it directly
maps the device in the system memory at a fixed
address that is not addressable by the ISA bus:

#define TPM_TIS_ADDR_BASE           0xFED40000

2/ it is not plugged to an ISA BUS (ISABus*)

3/ no machine plug it using isa_register_ioport()
   (it is not registered to the ISA memory space)

4/ the only thing slightly related to ISA is it
checks the IRQ number is < ISA_NUM_IRQS


So it seems this is a plain SysBusDevice. But then
there is TYPE_TPM_TIS_SYSBUS... What is the difference?

Thanks,

Phil.



             reply	other threads:[~2020-07-21 16:07 UTC|newest]

Thread overview: 6+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-07-21 16:02 Philippe Mathieu-Daudé [this message]
2020-07-21 16:38 ` What is TYPE_TPM_TIS_ISA? (Not an ISA Device) Stefan Berger
2020-07-21 16:40 ` Peter Maydell
2020-07-22  5:55   ` Markus Armbruster
2020-07-22 22:07     ` Stefan Berger
2020-07-23  9:10       ` Markus Armbruster

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