Date: Thu, 19 Mar 2015 18:35:40 -0300 From: =?UTF-8?Q?Mat=C3=ADas_Perret_Cantoni?= <perretcantonim@gmail.com> To: Thomas Skibo <thomasskibo@sbcglobal.net> Cc: freebsd-arm@freebsd.org Subject: Re: Zynq-7020 SoC on-chip-memory Message-ID: <CADLKG00%2BpruTnEA-MPdXZkbOcn7xzPna-z5itcv9sH1A3EnaeA@mail.gmail.com> In-Reply-To: <D2F57338-AC51-4A2D-982B-F024A5E422E4@sbcglobal.net> References: <CADLKG01oSQ=caZFOnZQM14=pAVPvLz45EznMes9mVfG2kD6TEQ@mail.gmail.com> <D2F57338-AC51-4A2D-982B-F024A5E422E4@sbcglobal.net>
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2015-03-19 16:19 GMT-03:00 Thomas Skibo <thomasskibo@sbcglobal.net>:
>
>
> > On Mar 19, 2015, at 9:58 AM, Mat=C3=ADas Perret Cantoni <perretcantonim=
@gmail.com> wrote:
> >
> > Hi everyone.
> >
> > The board I'm using (Zedboard) has a Zynq-7020 SoC which has 256KB of
> > on-chip-memory (OCM) with execute-in-place capabilities.
> > I'd like to add this memory as part of the system memory, but either I
> > can't add it, or I don't know how to "see it".
> >
> > Please let me know if this is not the right place to make this kind of
> > questions, I'll try to clarify myself:
> >
> > First of all I've checked all the registers that defines the memory map=
ping
> > and the address filtering behavior of the Snoop Control Unit, and it lo=
oks
> > like both CPUs sees this memory map:
> >
> > 0x0010_0000 0x1FF0_0000 0xFFFC_0000 0xFFFF_FFFF
> > / / /
> > /
> > +++++++++++++++++++++++++++++++
> > | |****************| =
|
> > | 511MB |****************| 256KB |
> > | (off chip RAM) |****************| (on chip RAM) |
> > | |****************| =
|
> > +++++++++++++++++++++++++++++++
> >
> > (I believe Thomas Skibo can easily correct me here)
>
> Yes, 0x0010_0000=E2=80=A60x1FFF_FFFF is off chip RAM. The first megabyte=
, 0x0000_0000..0x000F_FFFF, has a lot of caveats WRT devices accessing it s=
o I ignore it (See Table 4.1 in the Zynq Ref manual).
>
> I looked at the Snoop Control Unit registers on my Zedboard and the end a=
ddress is set to 0xffe00000. I don=E2=80=99t know much about the SCU but I=
assume that means the OCM region wouldn=E2=80=99t be cache-coherent betwee=
n the CPUs. And, I=E2=80=99m not sure where that register gets set.
I don't know either where this registers get set, but they have the
values that table 29-6 of the Zynq Reference Manual describes:
slcr.OCM_CFG[RAM_HI]=3D1111
mpcore.SCU_CONTROL_REGISTER[Address_Filtering_Enable]=3D1
mpcore.Filtering_Star_Address_Register=3D 0x0000_0000
mpcore.Filtering_End_Address_Register=3D 0xFFE0_0000
This means, I guess, that we have the memory mapping I've described before.
About coherency, I've read many times the chapters of the manual that
I've found relevant and I still can't tell whether access are coherent
or not.
>
> >
> > So far I modified the memory node of the dts file: The ePAPR specificat=
ion
> > says that If a system has multiple memory ranges one can create multipl=
e
> > memory nodes or just specify the ranges in the reg property of a single
> > memory node.
> >
> > The memory node of the dts file in HEAD is:
> >
> > memory {
> > // First megabyte isn't accessible by all interconnect masters.
> > device_type =3D "memory";
> > reg =3D <0x100000 0x1ff00000>; /* 511MB RAM at 0x100000 */
> > };
> >
> > My first attempt was to modify the reg property of the memory node:
> >
> > memory {
> > device_type =3D "memory";
> > reg =3D <0x100000 0x1ff00000>, /* 511MB RAM at 0x100000 */
> > <0xFFFC0000 0x3FFFF>; /* 256KB on-chip-memory at 0xfffc0000 */
> > };
>
> Shouldn=E2=80=99t it be <0xFFFC0000 0x40000>? I think it=E2=80=99ll stil=
l cause trouble, though.
Hum, I don't know. I'll try it tomorrow when I get to use the Zed.
>
>
> >
> > But the system hangs during boot. Then I tried to add a second memory n=
ode
> > for the on-chip-mem:
> >
> >
> > memory@100000 { // DDR3 RAM off-chip
> > device_type =3D "memory";
> > reg =3D <0x100000 0x1ff00000>; /* 511MB RAM at 0x100000 */
> > };
> >
> >
> > memory@FFFC0000 { // On-Chip-Memory
> > device_type =3D "memory";
> > reg =3D <0xFFFC0000 0x3FFFF>; /* 256KB at 0xFFFC0000 */
> > };
>
> I don=E2=80=99t think that (separate nodes) is supported. ??
>
>
> > In this case the system boots ok but I still see 511MB of system memory=
:
> >
> > root@zedboard:~ # dmesg | grep memory
> > real memory =3D 535822336 (511 MB)
> > avail memory =3D 515801088 (491 MB)
> >
> > db> show physmem
> > Physical memory chunk(s):
> > 0x00100000 - 0x1fffffff, 511 MB ( 130816 pages)
> > Excluded memory regions:
> > 0x00100000 - 0x007effff, 6 MB ( 1776 pages) NoAlloc
> >
> >
> > (Maybe I'm not checking properly :/ )
> >
> > ------
> > As an attempt to check If I can access this memory I added a device nod=
e in
> > the dts that represents the on-chip-memory. This isn't really useful bu=
t at
> > least I was able to read/write the memory with a simple newbus characte=
r
> > driver. The dts node I added is:
> >
> > ocm_area@FFFC0000 {
> > device_type =3D "soc";
> > compatible =3D "simple-bus";
> > #address-cells =3D <1>;
> > #size-cells =3D <1>;
> > ranges =3D <0x0 0xFFFC0000 0x3FFFF>; // OCM: 256KB
> >
> > ocm: ocm@0 {
> > compatible =3D "lac,ocm";
> > reg =3D <0x0 0xFF>; // First 128Bytes of OCM
> > };
> >
> > So the driver gets the resources:
> >
> > root@zedboard:/boot/msdos # devinfo -r | head
> > nexus0
> > ofwbus0
> > simplebus0
> > ocm_driver0
> > Device Memory:
> > 0xfffc0000-0xfffc00fe
> >
> > But here I would expected that the device's memory range
> > (0xfffc0000-0xfffcffff) was included in the devmap's ranges, but it's n=
ot:
> >
> > db> show devmap
> > Static device mappings:
> > 0xe0000000 - 0xe02fffff mapped at VA 0xffc00000
> > 0xf8000000 - 0xf8ffffff mapped at VA 0xfec00000
>
> These are only the static mappings set up in platform_devmap_init() in zy=
7_machdep.c. You can either add a static mapping in platform_devmap_init()=
so it shows up in =E2=80=9Cshow devmap=E2=80=9D or you can put a printf in=
your driver that prints the virtual address of the device memory at boot-u=
p.
Great, I didn't know this.
Thank you Thomas!
Regards.
>
> >
> >
> > So I can't inspect the on-chip-memory range from the debugger either.
> >
> > Any advice on how to add this memory to my system?
>
> I think it might be more trouble than it=E2=80=99s worth.
>
> Cheers,
> =E2=80=94Thomas
>
>
> =E2=80=94=E2=80=94=E2=80=94
> Thomas Skibo
> thomasskibo@sbcglobal.net
>
>
>
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