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3b79d32caf
expect to hear about this change. Note that Stefan and I have discussed
this change and feel it is at least worth trying.
Also, please be aware that this change is backed by a
lot of experience with LinuxBIOS users and usage of the last 7 years.
First I detail changes, then I detail why.
Major changes for the new config system.
Selection of object files, and variable setting, is now controlled by
Kconfig.
There is only one dts now. It is in the mainboard file. It may later
move to the target file -- we will see.
The dts is in two parts, seperated by %%. The first part is a
fairly standard dts, and the dtc will automatically generate a device
tree from it. The device tree is composed of generic structures. These
structures are identical to those of the old V2 device tree. All the
hierarchy and parent/child/sibling relationships appear to be correctly
generated. This means that all the v2 code will work without change.
For each node in the tree, if the node has a property named 'config',
then the dtc will generate a reference to a structure and an include
directive for a path -- much as in the old Config tool.
Example: here is a fragment of a dts
==========
north {
config = "northbridge,intel,i440bx";
};
%%
struct northbridge_intel_i440bx_config north = {
.whatever = 1;
};
===========
The dtc will create:
#include <northbridge/intel/i440gx/config.h>
struct northbridge_intel_i440bx_config north = {
.whatever = 1;
};
struct device dev_north {
.chip_ops = &northbridge_intel_i440bx_ops;
.chip_info = &north;
.
.
.
};
So the programmer specifies the tree structure in dts form, indicates
which devices have a config entry, and sets up the C code for the
config. I have worked with this and am finding it very easy to use. I
think this is the way to go. Plus, we are getting rid of most of the
include hell of the old Config system.
Note that the config node is OPTTONAL! If you do not set it then no
structure usage/include will occur.
WHY?
Here is my setup for v3. I think this is good. I like it and am
finding it easy to work with.
Basically, the old config system combined makefile generation, tree
generation, and chip struct initialization in one file -- config.lb.
What we need are four things:
1. selection of .c files to build the bios with
2. the device tree -- this is built with generic structures defined in
include/device/device.h
3. The per-chip structures, usually defined in, e.g.,
northbridge/intel/i440bx/chip.h
4. setting of variables such as baud rate, etc.
Again, this was all done in Config.lb, spread all over the place, like this:
config chip.h
object superio.o
This was hard for people. So we moved the makefile stuff out into the
Kconfig system. This change eliminates (1) and (4) above.
OK, what's left? Well, with our plans from last October, we had device
object model tree stuff, AND still had chip struct initialization in
one file. (2) and (3) above. This is tough, because I was fighting the
mapping of DTS stuff to the C code. It was getting just as ugly as the
old Config.lb. I have been struggling with this for months and it just
wasn't going anywhere.
But it's way too hard to set up the device tree by hand -- I've tried
it. OTOH, it's really easy to set up the per-chip stuff by hand --
I've tried that too. I did a search via:
find ~/src/LinuxBIOSv2/src/ -name chip.h -print
and looked at them all. These files are really simple. There's no
reason to get too tricky, as there is nothing worth getting tricky
about. The problem is the device tree, not these simple chip info
structs.
So, here's the solution.
The ONLY dts is in the mainboard directory. There is no equivalent of
Config.lb in the south, north, cpu, all that stuff any more. The
Kconfig and Makefile in those directories replaced the build-related
functions of Config.lb.-- (1) and (4) above. The only thing left was
chip.h anyway (3) above.
But how can we express the settings in chip.h via the DTS? IT's been
very hard to get this going.
So, here is the trick. The dts in the mainboard directory divides into
two parts. The first part is the standard dts. The second part is the
C code. They are seperated, as in lex and yacc, with a %%.
Here is the dts for qemu (note that the cpus keyword is still not
right, and maybe this structure needs to change; i'm not that worried
about that too much, just the big picture I'm discussing here). Also,
note I'm working with some new properties, e.g. pcipath and pcidomain
-- if these properties exist ina node, then I create initialized
structure members for them. Also see enabled and on_mainboard --
properties, but I catch them and use them.
/{
cpus {
config="mainboard,emulation,qemu-i386";
emulation,qemu-i386@0{
enabled;
on_mainboard;
device_type = "cpu";
name = "emulation,qemu-i386";
pcidomain = "0";
/* the I/O stuff */
northbridge,intel,440bx{
pcipath = "0,0";
southbridge,intel,piix4{
};
};
};
};
};
%%
/* the user sets up these structs */
struct mainboard_emulation_qemu_i386_config cpus = {
.nothing = 1,
};
You can see the device tree stuff at top. If a given node has a
property named 'config', then that means what the old 'chip' thing
meant in Config.lb. The dtc will generate an #include to pull in a
file with the path name specified in the config property. The dtc will
not set up the per-chip struct, but it will set up a pointer to a
struct when it sets up the device tree. Note that at bottom, it's up
to you to set up the initialized struct. But this was always the easy
part anyway. Instead of wacky pseudo-C like we had in config.lb, we
just do real C. It's easy. Here is what the dtc generates.
#include <device/device.h>
#include <device/pci.h>
#include <mainboard/emulation/qemu-i386/config.h>
struct device dev_southbridge_intel_piix4;
struct device dev_northbridge_intel_440bx;
struct device dev_emulation_qemu_i386_0;
struct device dev_cpus;
struct device dev_root;
extern struct chip_operations mainboard_emulation_qemu_i386_ops;
struct mainboard_emulation_qemu_i386_config cpus = {
.nothing = 1,
};
struct device dev_root = {
.path = { .type = DEVICE_PATH_ROOT },
.links = 1,
.link = {
[0] = {
.dev = &dev_root,
.link = 0,
.children = &dev_cpus
},
},
.bus = &dev_root.link[0],
};
struct device dev_cpus = {
.chip_ops = &mainboard_emulation_qemu_i386_ops,
.chip_info = &cpus,
.links = 1,
.link = {
[0] = {
.dev = &dev_cpus,
.link = 0,
.children = &dev_emulation_qemu_i386_0
},
},
.bus = &dev_root.link[0],
.next = &dev_root,
};
struct device dev_emulation_qemu_i386_0 = {
.enabled = 1,
.on_mainboard = 1,
.path = {.type=DEVICE_PATH_PCI_DOMAIN,.u={.pci_domain={ .domain = 0 }}}
,
.links = 1,
.link = {
[0] = {
.dev = &dev_emulation_qemu_i386_0,
.link = 0,
.children = &dev_northbridge_intel_440bx
},
},
.bus = &dev_cpus.link[0],
.next = &dev_cpus,
};
struct device dev_northbridge_intel_440bx = {
.path = {.type=DEVICE_PATH_PCI,.u={.pci={ .devfn = PCI_DEVFN(0,0)}}},
.links = 1,
.link = {
[0] = {
.dev = &dev_northbridge_intel_440bx,
.link = 0,
.children = &dev_southbridge_intel_piix4
},
},
.bus = &dev_emulation_qemu_i386_0.link[0],
.next = &dev_emulation_qemu_i386_0,
};
struct device dev_southbridge_intel_piix4 = {
.bus = &dev_northbridge_intel_440bx.link[0],
.next = &dev_northbridge_intel_440bx,
};
This compiles just fine.
I think this is the right way to go, comments to me.
But, note, IT COMPILES. And it's simple. And, it will work with our
current device tree code!
Signed-off-by: Ronald G. Minnich <rminnich@gmail.com>
Acked-by: Stefan Reinauer <stepan@coresystems.de>
git-svn-id: svn://coreboot.org/repository/LinuxBIOSv3@59 f3766cd6-281f-0410-b1cd-43a5c92072e9
|
||
|---|---|---|
| .. | ||
| Documentation | ||
| tests | ||
| comment-test.dts | ||
| COPYING | ||
| data.c | ||
| dtc-lexer.l | ||
| dtc-parser.y | ||
| dtc.c | ||
| dtc.h | ||
| dtsqemu | ||
| flat_dt.h | ||
| flattree.c | ||
| fstree.c | ||
| ftdump.c | ||
| libdt.c | ||
| livetree.c | ||
| Makefile | ||
| newstatic.c | ||
| test.dts | ||
| TODO | ||
| treesource.c | ||