Date: Thu, 23 Jul 2009 08:35:50 -0400 From: John Baldwin <jhb@freebsd.org> To: freebsd-hackers@freebsd.org Cc: Andre Albsmeier <Andre.Albsmeier@siemens.com> Subject: Re: Reading acpi memory from a driver attached to hostb Message-ID: <200907230835.50814.jhb@freebsd.org> In-Reply-To: <20090723060835.GB62628@curry.mchp.siemens.de> References: <20090718133938.GA7802@curry.mchp.siemens.de> <200907221648.n6MGmu58035040@ambrisko.com> <20090723060835.GB62628@curry.mchp.siemens.de>
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On Thursday 23 July 2009 2:08:35 am Andre Albsmeier wrote: > On Wed, 22-Jul-2009 at 09:48:56 -0700, Doug Ambrisko wrote: > > Andre Albsmeier writes: > > | On Sat, 18-Jul-2009 at 10:25:06 +0100, Rui Paulo wrote: > > | > On 18 Jul 2009, at 09:10, Andre Albsmeier wrote: > > | > > > | > > On Fri, 17-Jul-2009 at 12:53:53 -0700, Julian Elischer wrote: > > | > >> Andre Albsmeier wrote: > > | > >>> [CC'ing this to Rui Paulo since he tried to help me a while ago] > > | > >>> > > | > >>> Since my driver is a child of hostb0, I have no idea of how to > > | > >>> access > > | > >>> acpi0's memory area. Here is a devinfo -r to make things clear: > > | > >>> > > | > >> ... > > | > >>> > > | > >>> Earlier, I was given the hint to attach as a child of acpi (see the > > | > >>> old mail attached below) but in this case I didn't have access to > > | > >>> the > > | > >>> hostb registers which I need as well. > > | > >>> > > | > >>> The only thing I see is: Attach two drivers -- one as child of acpi > > | > >>> and another as child of hostb and let them communicate somehow (no > > | > >>> idea how to do this). > > | > >>> > > | > >>> I have also done crazy things like searching for acpi0 and trying > > | > >>> to bus_alloc_resource() the memory I am interested in but this also > > | > >>> failed. > > | > >>> > > | > >>> Or is it possible to free(!) somehow the address space from acpi0 > > | > >>> and pass it to hostb0 so I can bus_alloc_resource() it? > > | > >>> > > | > >> > > | > >> You can probably make two drivers in one which cooperate to > > | > >> allow access to both sets of resources. > > | > > > > | > > Hmm, that's what I meant by: Attach two drivers -- one as child of > > | > > acpi > > | > > and another as child of hostb... > > | > > > > | > > And that's similar to Rui Paulo's suggestion a while ago: > > | > > > > | > >> 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. > > | > > > > | > > But in order to attach to acpi0, I need to say > > | > > > > | > > DRIVER_MODULE( eccmon, acpi, eccmon_driver, eccmon_devclass, NULL, > > | > > NULL ); > > | > > > > | > > instead of > > | > > > > | > > DRIVER_MODULE( eccmon, hostb, eccmon_driver, eccmon_devclass, NULL, > > | > > NULL ); > > | > > > > | > > This way I could attach to acpi but not to hostb anymore.... > > | > > > > | > > I have searched the net for solutions, I have read newbus-draft.txt > > | > > and newbus-intro.txt and Warner Losh's newbus-led.c (thanks to all > > | > > of these my driver is working on other mainboards where it doesn't > > | > > have to access foreign memory) but didn't find anything. > > | > > > | > I'm out of ideas. > > | > John, do you know if this is a newbus limitation or if it can be > > | > worked around ? > > | > > | I assume it is possible somehow, I am just too stupid (it is the first > > | driver I wrote). John, for easy reference, here is my initial message: > > | > > | http://lists.freebsd.org/pipermail/freebsd-hackers/2009-July/029127.html > > | > > | Please remember all, that I need the access to the acpi0 memory location > > | only for a few reads during probing/attaching, not later. > > | > > | I have also read somewhere that, when resources are allocated, the > > | system "walks up" the device tree until it finds the resource. Since > > | my driver is below hostb0 and hostb0 is below acpi0 I thought it > > | should work but it doesn't.. > > > > FWIW, you might look at ipmi(4) especially in some early states since > > it can probe and attach in many ways (isa, acpi, pci etc.) and had to > > figure out the best way to attach. Also it had various front ends. > > If I recall correctly, I did a find for a driver (ie. acpi) then > > select the first instance. Once you get that handle then you can > > request device resources from it, get the info you need then release > > that stuff. However, you won't get the module auto-loading part > > that you would get if you created a module that depended on both. > > That might get you enough of a hint. Also there are some generic > > stuff to read various memory bits like SMBIOS areas etc. This is > > used in ipmi(4) as well since the attachment can be defined in SMBIOS. > > If you have a specific question, about why the driver did something > > I should recall that. The ipmi(4) driver is in fairly clean. There > > is some improvements I still need to do on probe/attachment that > > causes a bogus ipmi1 at times. > > Thanks a lot for this interesting information. I see, things are more > complicated than I thought. There is no easy way having a quick glance > at "foreign" memory during probing. Now I have to figure out how to get > the order of probing/attaching done. One thing I could do is: > > 1. attach mydriver_ACPI to acpi0 > > 2. probe mydriver under hostb0, check if we need access to > sysresources from acpi0 (depends on the chipset found). > If no, goto 5. > > 3. ask mydriver_ACPI about stuff I want to know (HOW?) > > 4. tell mydriver to detach from acpi0 (HOW?) > > 5. attach mydriver to hostb0 and do my work > > What I would like more is something like: > > 1. probe mydriver under hostb0, check if we need access to > sysresources from acpi0 (depends on the chipset found). > If no, goto 3. > > 2. ask mydriver_ACPI to attach to acpi0, give me the info > I want, detach mydriver_ACPI (HOW?) > > 3. attach mydriver to hostb0 and do my work Did you try doing 'bus_alloc_resource(device_get_parent(device_get_parent(dev))' in your driver that is a child of hostb0? -- John Baldwin
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