[U-Boot-Users] [PATCH 1/2] add ft_cpu_setup(..) on mpc8260
add ft_cpu_setup(..)-function to adapt it for use with libfdt based on code from mpc5xxx
Sigend-off-by: Sergej Stepanov Sergej.Stepanov@ids.de ---
diff --git a/cpu/mpc8260/cpu.c b/cpu/mpc8260/cpu.c index 94651dc..8e78d89 100644 --- a/cpu/mpc8260/cpu.c +++ b/cpu/mpc8260/cpu.c @@ -38,6 +38,9 @@ * * added HiP7 (824x/827x/8280) processors support by * Yuli Barcohen yuli@arabellasw.com + * + * add ft_cpu_setup(..) for use with CONFIG_OF_LIBFDT + * Sergej Stepanov Sergej.Stepanov@ids.de */
#include <common.h> @@ -47,6 +50,11 @@ #include <asm/processor.h> #include <asm/cpm_8260.h>
+#if defined(CONFIG_OF_LIBFDT) +#include <libfdt.h> +#include <libfdt_env.h> +#endif + DECLARE_GLOBAL_DATA_PTR;
#if defined(CONFIG_GET_CPU_STR_F) @@ -294,3 +302,36 @@ void watchdog_reset (void) #endif /* CONFIG_WATCHDOG */
/* ------------------------------------------------------------------------- */ +#if defined(CONFIG_OF_LIBFDT) +static void do_fixup(void *fdt, const char *node, const char *prop, + const void *val, int len, int create) +{ +#if defined(DEBUG) + int i; + debug("Updating property '%s/%s' = ", node, prop); + for (i = 0; i < len; i++) + debug(" %.2x", *(u8*)(val+i)); + debug("\n"); +#endif + int rc = fdt_find_and_setprop(fdt, node, prop, val, len, create); + if (rc) + printf("Unable to update property %s:%s, err=%s\n", + node, prop, fdt_strerror(rc)); +} + +static void do_fixup_u32(void *fdt, const char *node, const char *prop, + u32 val, int create) +{ + val = cpu_to_fdt32(val); + do_fixup(fdt, node, prop, &val, sizeof(val), create); +} + +void ft_cpu_setup (void *blob, bd_t *bd) +{ + char * cpu_path = "/cpus/" OF_CPU; + + do_fixup_u32(blob, cpu_path, "bus-frequency", bd->bi_busfreq, 1); + do_fixup_u32(blob, cpu_path, "timebase-frequency", OF_TBCLK, 1); + do_fixup_u32(blob, cpu_path, "clock-frequency", bd->bi_intfreq, 1); +} +#endif /* CONFIG_OF_LIBFDT */
In message 1192605168.3174.17.camel@p60635-ste.ids.de you wrote:
add ft_cpu_setup(..)-function to adapt it for use with libfdt based on code from mpc5xxx
Sigend-off-by: Sergej Stepanov Sergej.Stepanov@ids.de
diff --git a/cpu/mpc8260/cpu.c b/cpu/mpc8260/cpu.c index 94651dc..8e78d89 100644 --- a/cpu/mpc8260/cpu.c +++ b/cpu/mpc8260/cpu.c @@ -38,6 +38,9 @@
- added HiP7 (824x/827x/8280) processors support by
- Yuli Barcohen yuli@arabellasw.com
- add ft_cpu_setup(..) for use with CONFIG_OF_LIBFDT
*/
- Sergej Stepanov Sergej.Stepanov@ids.de
Please omit such change log comments. We have the git history for that.
[Please fix and resubmit.]
Best regards,
Wolfgang Denk
I have some confusion about FDT and what the intentions are for its support and usage in u-boot.
From what I understand so far, u-boot only supports modifying a FDT
already loaded into memory. Isn't this kind of an odd usage of a device tree? I thought a unique tree should be created for each hardware implementation (a.k.a. system board) and therefore you shouldn't be modifying it. If changes are made a new device tree should be created.
What is the intent for future support? Creation of a device tree from scratch? That seems to be what the original (open firmware) intention of FDTs were. (Allowing a bootloader to pass a implementation specific hardware list up to an operating system.) And the current Linux implementation is a little backwards from that (let kernel compiler give you a device tree which you then have to give to the bootloader to pass back up to the kernel during boot). It would seem to make more sense (in my limited understanding of FDT) to allow the bootloader to be able to generate this itself without dependence on a prior kernel compilation for that particular hardware...
If the plans aren't for u-boot to have the ability to generate a device tree would it be reasonable to create one and embed it in the u-boot binary somehow? (so that another unique binary wouldn't have to be loaded into another separate flash partition)
Thanks, Zach
Zach Sadecki wrote:
I have some confusion about FDT and what the intentions are for its support and usage in u-boot.
From what I understand so far, u-boot only supports modifying a FDT already loaded into memory. Isn't this kind of an odd usage of a device tree? I thought a unique tree should be created for each hardware implementation (a.k.a. system board) and therefore you shouldn't be modifying it. If changes are made a new device tree should be created.
You can only _modify_ a blob when it is in RAM. You can store a blob in ROM (flash) and copy it to RAM for modification.
If you don't need to modify the blob in order to boot linux, there is no need (that I'm aware of) for loading/copying it to RAM. *However* it is unlikely that you (u-boot/linux) will be able to use an unmodified blob. For instance, the "chosen" node is (or should be?) generated by the boot loader (u-boot) to let the kernel know about certain choices that were made by the boot loader and/or the user.
The intent is to set properties (values) that can change from boot to boot or from board to board. The classic example are clocks. Boards, when they boot, can typically figure out and often can set clock rates. Having a thousand FDTs with all the combinations of possible clocks is a maintenance nightmare. Having u-boot set the clocks or probe for the clock rates is great.
What is the intent for future support? Creation of a device tree from scratch? That seems to be what the original (open firmware) intention of FDTs were. (Allowing a bootloader to pass a implementation specific hardware list up to an operating system.) And the current Linux implementation is a little backwards from that (let kernel compiler give you a device tree which you then have to give to the bootloader to pass back up to the kernel during boot). It would seem to make more sense (in my limited understanding of FDT) to allow the bootloader to be able to generate this itself without dependence on a prior kernel compilation for that particular hardware...
There is no intention to create blobs from scratch in the boot loader (u-boot). If you look at some of the SOC (8[3456]xx) blobs, you would see that that would be a nightmare, your fingers would be bloody stubs by the time you typed it all in, and then you would find you had a syntax error and have to start all over. http://pez.multiply.com/journal/item/75/Computer_Frustration (I think that is the link, the filters at work don't let me browse it.)
On the other hand, 98% of the typical FDT blob (to make up a statistic) is static. The intent of u-boot FDT support is to externally (via the dtc) generate a blob with the 98% already filled in and have u-boot configure the 2% that is board-specific or user selected.
The blob can be baked into u-boot, stored in flash separately from u-boot, or loaded as part of the kernel (baked into the kernel image in ROM, tftped separately from the kernel, tftped as part of the kernel image).
We are in the tool business, how to use the tool is up to the user. ;-)
If the plans aren't for u-boot to have the ability to generate a device tree would it be reasonable to create one and embed it in the u-boot binary somehow? (so that another unique binary wouldn't have to be loaded into another separate flash partition)
Thanks, Zach
That option is already there as a multi-image boot image, one part of the image being a FDT blob.
Best regards, gvb
On Wed, 2007-10-17 at 11:02 -0400, Jerry Van Baren wrote:
Zach Sadecki wrote:
I have some confusion about FDT and what the intentions are for its support and usage in u-boot.
From what I understand so far, u-boot only supports modifying a FDT already loaded into memory. Isn't this kind of an odd usage of a device tree? I thought a unique tree should be created for each hardware implementation (a.k.a. system board) and therefore you shouldn't be modifying it. If changes are made a new device tree should be created.
You can only _modify_ a blob when it is in RAM. You can store a blob in ROM (flash) and copy it to RAM for modification.
If you don't need to modify the blob in order to boot linux, there is no need (that I'm aware of) for loading/copying it to RAM. *However* it is unlikely that you (u-boot/linux) will be able to use an unmodified blob. For instance, the "chosen" node is (or should be?) generated by the boot loader (u-boot) to let the kernel know about certain choices that were made by the boot loader and/or the user.
OT, but I have always wondered how the chosen node is supposed to be used. Would it be possible to specify which devices in the device tree that should be used by the OS? Supposed I got two boards that are identical, except one of them does not have ethernet i/f. Would it be possible use the same device tree for both boards, but tell OS that the ethernet i/f isn't present on one of the boards?
I getting a bunch of boards thats are very similiar from the OS point of view and I would like to just have one mega devtree and remove some devices at runtime or change som properties.
Jocke
Joakim Tjernlund wrote:
On Wed, 2007-10-17 at 11:02 -0400, Jerry Van Baren wrote:
Zach Sadecki wrote:
I have some confusion about FDT and what the intentions are for its support and usage in u-boot.
From what I understand so far, u-boot only supports modifying a FDT already loaded into memory. Isn't this kind of an odd usage of a device tree? I thought a unique tree should be created for each hardware implementation (a.k.a. system board) and therefore you shouldn't be modifying it. If changes are made a new device tree should be created.
You can only _modify_ a blob when it is in RAM. You can store a blob in ROM (flash) and copy it to RAM for modification.
If you don't need to modify the blob in order to boot linux, there is no need (that I'm aware of) for loading/copying it to RAM. *However* it is unlikely that you (u-boot/linux) will be able to use an unmodified blob. For instance, the "chosen" node is (or should be?) generated by the boot loader (u-boot) to let the kernel know about certain choices that were made by the boot loader and/or the user.
OT, but I have always wondered how the chosen node is supposed to be used.
I'm not an expert, I only play on on mail lists. My understanding is that the chosen node indicates to the OS what choices the user (or boot loader) made between possible configurations...
Would it be possible to specify which devices in the device tree that should be used by the OS?
...so the answer should be "yes" but that is making the assumption that the OS knows enough to look in the chosen node to figure out which devices it should use. *That* part is probably a bad assumption (at the moment).
Supposed I got two boards that are identical, except one of them does not have ethernet i/f. Would it be possible use the same device tree for both boards, but tell OS that the ethernet i/f isn't present on one of the boards?
I believe the theoretical answer is "yes" but the practical answer is "no" for doing this via the "chosen" node.
It is simpler and safer to use libfdt to simply delete the unpopulated node from the tree.
I getting a bunch of boards thats are very similiar from the OS point of view and I would like to just have one mega devtree and remove some devices at runtime or change som properties.
Jocke
Hopefully your boards have some method of self-determining what is populated or not. Alternatively, you can use the ability to load board-specific FDT blobs to accomplish this.
Wolfgang Grandegger and Delev Zundel actually created a "universal" u-boot that was configured *itself* via a FDT blob (OK, it wasn't universal, but it sounds so good). If your board isn't self-aware of its configuration, that would be an interesting path to go down.
gvb
Jerry Van Baren wrote:
Zach Sadecki wrote:
I have some confusion about FDT and what the intentions are for its support and usage in u-boot.
From what I understand so far, u-boot only supports modifying a FDT already loaded into memory. Isn't this kind of an odd usage of a device tree? I thought a unique tree should be created for each hardware implementation (a.k.a. system board) and therefore you shouldn't be modifying it. If changes are made a new device tree should be created.
You can only _modify_ a blob when it is in RAM. You can store a blob in ROM (flash) and copy it to RAM for modification.
If you don't need to modify the blob in order to boot linux, there is no need (that I'm aware of) for loading/copying it to RAM. *However* it is unlikely that you (u-boot/linux) will be able to use an unmodified blob. For instance, the "chosen" node is (or should be?) generated by the boot loader (u-boot) to let the kernel know about certain choices that were made by the boot loader and/or the user.
The intent is to set properties (values) that can change from boot to boot or from board to board. The classic example are clocks. Boards, when they boot, can typically figure out and often can set clock rates. Having a thousand FDTs with all the combinations of possible clocks is a maintenance nightmare. Having u-boot set the clocks or probe for the clock rates is great.
OK, I see your point here. That makes sense...
What is the intent for future support? Creation of a device tree from scratch? That seems to be what the original (open firmware) intention of FDTs were. (Allowing a bootloader to pass a implementation specific hardware list up to an operating system.) And the current Linux implementation is a little backwards from that (let kernel compiler give you a device tree which you then have to give to the bootloader to pass back up to the kernel during boot). It would seem to make more sense (in my limited understanding of FDT) to allow the bootloader to be able to generate this itself without dependence on a prior kernel compilation for that particular hardware...
There is no intention to create blobs from scratch in the boot loader (u-boot). If you look at some of the SOC (8[3456]xx) blobs, you would see that that would be a nightmare, your fingers would be bloody stubs by the time you typed it all in, and then you would find you had a syntax error and have to start all over. http://pez.multiply.com/journal/item/75/Computer_Frustration (I think that is the link, the filters at work don't let me browse it.)
What I meant was not typing it in by hand, but setting it up in your board.h file so that it can be generated during compile or during boot. But if you can embed it into the u-boot image itself, maybe this is unnecessary. It seems as I look deeper into the code it does support this to some extent (ft_build.c), but I think that it might not be as thorough as it would need to be to work.
On the other hand, 98% of the typical FDT blob (to make up a statistic) is static. The intent of u-boot FDT support is to externally (via the dtc) generate a blob with the 98% already filled in and have u-boot configure the 2% that is board-specific or user selected.
The blob can be baked into u-boot, stored in flash separately from u-boot, or loaded as part of the kernel (baked into the kernel image in ROM, tftped separately from the kernel, tftped as part of the kernel image).
We are in the tool business, how to use the tool is up to the user. ;-)
If the plans aren't for u-boot to have the ability to generate a device tree would it be reasonable to create one and embed it in the u-boot binary somehow? (so that another unique binary wouldn't have to be loaded into another separate flash partition)
Thanks, Zach
That option is already there as a multi-image boot image, one part of the image being a FDT blob.
I've seen a little info on using mkimage to add an initrd, but nothing specifically with fdt (or dtb). I've seen no info on 'baking it into u-boot' that you mentioned above... Is there any documentation on how to do either of these?
Thanks, Zach
Zach Sadecki wrote:
Jerry Van Baren wrote:
Zach Sadecki wrote:
I have some confusion about FDT and what the intentions are for its support and usage in u-boot.
[snip]
What is the intent for future support? Creation of a device tree from scratch? That seems to be what the original (open firmware) intention of FDTs were. (Allowing a bootloader to pass a implementation specific hardware list up to an operating system.) And the current Linux implementation is a little backwards from that (let kernel compiler give you a device tree which you then have to give to the bootloader to pass back up to the kernel during boot). It would seem to make more sense (in my limited understanding of FDT) to allow the bootloader to be able to generate this itself without dependence on a prior kernel compilation for that particular hardware...
There is no intention to create blobs from scratch in the boot loader (u-boot). If you look at some of the SOC (8[3456]xx) blobs, you would see that that would be a nightmare, your fingers would be bloody stubs by the time you typed it all in, and then you would find you had a syntax error and have to start all over. http://pez.multiply.com/journal/item/75/Computer_Frustration (I think that is the link, the filters at work don't let me browse it.)
What I meant was not typing it in by hand, but setting it up in your board.h file so that it can be generated during compile or during boot. But if you can embed it into the u-boot image itself, maybe this is unnecessary. It seems as I look deeper into the code it does support this to some extent (ft_build.c), but I think that it might not be as thorough as it would need to be to work.
Hmmm /me thinks you are confusing libfdt and The Other Way of supporting FDT blobs with the reference to ft_build.c. While it is theoretically true that you could generate the blob from nothing, modifying and augmenting a static initial blob makes more sense.
I would not advocate embedding the FDT blob in u-boot but, if I were to do so, I would use the dtc to generate an assembly language output (actually, a lot of define byte statements) and then compile that in the u-boot build.
A better approach IMHO (subject to change) is to burn the FDT blob into a separate flash area so it can be updated later without rebuilding u-boot or downloading it via TFTP. Obviously, this would be an engineering tradeoff and /your/ best choice for your situation is quite likely different from someone else's choice for their (different) situation.
On the other hand, 98% of the typical FDT blob (to make up a statistic) is static. The intent of u-boot FDT support is to externally (via the dtc) generate a blob with the 98% already filled in and have u-boot configure the 2% that is board-specific or user selected.
The blob can be baked into u-boot, stored in flash separately from u-boot, or loaded as part of the kernel (baked into the kernel image in ROM, tftped separately from the kernel, tftped as part of the kernel image).
We are in the tool business, how to use the tool is up to the user. ;-)
If the plans aren't for u-boot to have the ability to generate a device tree would it be reasonable to create one and embed it in the u-boot binary somehow? (so that another unique binary wouldn't have to be loaded into another separate flash partition)
Thanks, Zach
That option is already there as a multi-image boot image, one part of the image being a FDT blob.
I've seen a little info on using mkimage to add an initrd, but nothing specifically with fdt (or dtb). I've seen no info on 'baking it into u-boot' that you mentioned above... Is there any documentation on how to do either of these?
Thanks, Zach
I haven't tried to make a multi-image linux/FDT blob/RAM disk an may have misspoke about it being an option. What I was recalling is something Timur did which was using mkimage to wrap a standalone blob. http://thread.gmane.org/gmane.comp.boot-loaders.u-boot/28207/focus=28242
Baking in - explained above, use dtc to generate assembly and link it in with u-boot. It may make sense in places, but I would think hard about if it made sense before doing it.
gvb
On Thu, 18 Oct 2007 15:29:28 -0400 Jerry Van Baren gerald.vanbaren@ge.com wrote:
I would not advocate embedding the FDT blob in u-boot but, if I were to do so, I would use the dtc to generate an assembly language output (actually, a lot of define byte statements) and then compile that in the u-boot build.
Why not just generate a binary file (possibly compressed) and suck it into an assembly file using .incbin?
A better approach IMHO (subject to change) is to burn the FDT blob into a separate flash area so it can be updated later without rebuilding u-boot or downloading it via TFTP. Obviously, this would be an engineering tradeoff and /your/ best choice for your situation is quite likely different from someone else's choice for their (different) situation.
Yes, having a mutable device tree probably makes more sense for a development board. But embedding it in the u-boot binary could save some space in the "production" image. Is it possible to support both?
I don't know all that much about FDT, so I could be way off. I would like to try it out with avr32 at some point though, after all the basics are in place.
Håvard
Haavard Skinnemoen wrote:
On Thu, 18 Oct 2007 15:29:28 -0400 Jerry Van Baren gerald.vanbaren@ge.com wrote:
I would not advocate embedding the FDT blob in u-boot but, if I were to do so, I would use the dtc to generate an assembly language output (actually, a lot of define byte statements) and then compile that in the u-boot build.
Why not just generate a binary file (possibly compressed) and suck it into an assembly file using .incbin?
Yet Another Way to do the same thing. Dtc produces a binary blob or human readable assembly, might as well output assembly and skip the .incbin, but to each their own.
Compressing probably isn't profitable, a blob is a few K uncompressed. On the other hand, u-boot knows how to uncompress, so anything is possible...
A better approach IMHO (subject to change) is to burn the FDT blob into a separate flash area so it can be updated later without rebuilding u-boot or downloading it via TFTP. Obviously, this would be an engineering tradeoff and /your/ best choice for your situation is quite likely different from someone else's choice for their (different) situation.
Yes, having a mutable device tree probably makes more sense for a development board. But embedding it in the u-boot binary could save some space in the "production" image. Is it possible to support both?
Yes. Ultimately u-boot (mboot/linux) takes the address of the blob. You can store it anywhere you want, as long as it has an address. If it doesn't have an address (e.g. i2c eeprom, NAND flash), you simply need to copy it somewhere addressable (RAM) first. U-boot knows how to cp too. :-)
I don't know all that much about FDT, so I could be way off. I would like to try it out with avr32 at some point though, after all the basics are in place.
Håvard
You have the concepts OK. FDT is pretty cool stuff, much better than shared "bd" structures.
gvb
On Wed, Oct 17, 2007 at 09:12:48AM +0200, Sergej Stepanov wrote:
+void ft_cpu_setup (void *blob, bd_t *bd) +{
- char * cpu_path = "/cpus/" OF_CPU;
- do_fixup_u32(blob, cpu_path, "bus-frequency", bd->bi_busfreq, 1);
- do_fixup_u32(blob, cpu_path, "timebase-frequency", OF_TBCLK, 1);
- do_fixup_u32(blob, cpu_path, "clock-frequency", bd->bi_intfreq, 1);
+}
You should also fix up /soc/cpm/brg/clock-frequency.
-Scott
Am Dienstag, den 23.10.2007, 14:34 -0500 schrieb Scott Wood:
On Wed, Oct 17, 2007 at 09:12:48AM +0200, Sergej Stepanov wrote:
+void ft_cpu_setup (void *blob, bd_t *bd) +{
- char * cpu_path = "/cpus/" OF_CPU;
- do_fixup_u32(blob, cpu_path, "bus-frequency", bd->bi_busfreq, 1);
- do_fixup_u32(blob, cpu_path, "timebase-frequency", OF_TBCLK, 1);
- do_fixup_u32(blob, cpu_path, "clock-frequency", bd->bi_intfreq, 1);
+}
You should also fix up /soc/cpm/brg/clock-frequency.
I will do it. But before i have the question: could somebody tell me, are there more other things to fix up?
Thanks. Sergej.
participants (9)
-
Haavard Skinnemoen -
Jerry Van Baren -
Jerry Van Baren -
Joakim Tjernlund -
Scott Wood -
Sergej Stepanov -
Wolfgang Denk -
Zach Sadecki -
Zach Sadecki