From owner-freebsd-hackers@FreeBSD.ORG Sun Dec 28 10:54:04 2008 Return-Path: Delivered-To: freebsd-hackers@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34]) by hub.freebsd.org (Postfix) with ESMTP id 7A7A81065670 for ; Sun, 28 Dec 2008 10:54:04 +0000 (UTC) (envelope-from Andre.Albsmeier@siemens.com) Received: from goliath.siemens.de (goliath.siemens.de [192.35.17.28]) by mx1.freebsd.org (Postfix) with ESMTP id 0ED128FC13 for ; Sun, 28 Dec 2008 10:54:03 +0000 (UTC) (envelope-from Andre.Albsmeier@siemens.com) Received: from mail3.siemens.de (localhost [127.0.0.1]) by goliath.siemens.de (8.12.11.20060308/8.12.11) with ESMTP id mBSAs1fU027357; Sun, 28 Dec 2008 11:54:02 +0100 Received: from curry.mchp.siemens.de (curry.mchp.siemens.de [139.25.40.130]) by mail3.siemens.de (8.12.11.20060308/8.12.11) with ESMTP id mBSAs16L027577; Sun, 28 Dec 2008 11:54:01 +0100 Received: (from localhost) by curry.mchp.siemens.de (8.14.3/8.14.3) id mBSAs1Vr082193; Date: Sun, 28 Dec 2008 11:54:01 +0100 From: Andre Albsmeier To: Rui Paulo Message-ID: <20081228105401.GA28657@curry.mchp.siemens.de> References: <20081225095333.GA12699@curry.mchp.siemens.de> <490EB16A-F626-4A40-9716-A02A32F04ED4@freebsd.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <490EB16A-F626-4A40-9716-A02A32F04ED4@freebsd.org> X-Echelon: X-Advice: Drop that crappy M$-Outlook, I'm tired of your viruses! User-Agent: Mutt/1.5.18 (2008-05-17) Cc: freebsd-hackers@freebsd.org, Andre Albsmeier Subject: Re: Writing device drivers: How to access a specific memory area? X-BeenThere: freebsd-hackers@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: Technical Discussions relating to FreeBSD List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Sun, 28 Dec 2008 10:54:04 -0000 On Thu, 25-Dec-2008 at 13:57:00 +0000, Rui Paulo wrote: > > On 25 Dec 2008, at 09:53, Andre Albsmeier wrote: > > > Hello all, > > > > I am writing a driver which needs to access memory at a > > specific location. The location depends on what the BIOS > > has configured into the host bridge. For example, my > > current machine uses an Intel 975X chipset and the memory > > location I am interested in has been set to 0xFED14000 and > > is 16KB in size (this is MCHBAR of the 975X memory hub). > > You probably just need to do something like: > > rid = PCI_BAR(number); > res = bus_alloc_resource_any(dev, SYS_RES_MEMORY, &rid, RF_ACTIVE); The problem was, that this memory belongs to acpi0 so I couldn't read it from my driver which has no resources assigned to it. But, I found a way, see below... > > And then, > bus_read_4(res, offset from specified PCI BAR); > > > > > > > I have no idea how to access this space from my driver. > > I have played around with bus_alloc_resource() but this > > only gives me back NULL. > > > > However, a devinfo -r gives me: > > > > nexus0 > > npx0 > > acpi0 > > Interrupt request lines: > > 9 > > I/O ports: > > 0x10-0x1f > > ... > > 0x800-0x87f > > I/O memory addresses: > > 0x0-0x9ffff > > 0xc0000-0xdffff > > 0xe0000-0xfffff > > 0x100000-0x7fffffff > > 0xf0000000-0xf3ffffff > > 0xfec00000-0xfec00fff > > 0xfed13000-0xfed19fff <--- > > 0xfed1c000-0xfed1ffff > > 0xfed20000-0xfed3ffff > > 0xfed50000-0xfed8ffff > > 0xfee00000-0xfee00fff > > 0xffb00000-0xffbfffff > > 0xfff00000-0xffffffff > > cpu0 > > ... > > > > The line marked with <--- shows the range which includes > > the location I am interested in. It is probably assigned > > to the acpi0 device. > > > > How do I proceed from this? Do I have to hack around in > > the ACPI-Code? I don't hope so ;-) > > You'll probably need to create a fake ACPI child driver to access it. > > > Create your identify routine with something like: > > static void mydriver_identify(driver_t *driver, device_t parent) > { > if (device_find_child(parent, "mydriver", -1) == NULL && > mydriver_match(parent)) > device_add_child(parent, "mydriver", -1); > } > > mydriver_match() should check if you were given the acpi0 device. Found something easier: I just do a bus_set_resource() followed by bus_alloc_resource_any(), access my host bridge registers, and free things with bus_release_resource() followed by bus_delete_resource(). > > > > > > > > I only need access to this memory location during the > > probe of my driver to read some configuration data. > > Is this pci configuration space ? If so, pci_read_config (man 9 pci) Unfortunately not. As I wrote, it is a 16k memory window where the 975x maps a part of its config registers. The address of this window can be read by pci_read_config( dev, 0x44, 4 ). Then you can access the bridge's cXdrcY registers through this memory window which I needed to determine the machines RAM layout. Thanks anyway for your help, -Andre