| Message ID | 150b7c8a91ea9843d34fd8e8ceeca3fa2d0d121b.1479913469.git.mario.six@gdsys.cc |
|---|---|
| State | Superseded |
| Delegated to: | Stefan Roese |
| Headers | show |
(Adding Simon and Maxim to Cc) On 23.11.2016 16:12, Mario Six wrote: > Certain boards come in different variations by way of utilizing daughter > boards, for example. These boards might contain additional chips, which > are added to the main board's busses, e.g. I2C. > > The device tree support for such boards would either, quite naturally, > employ the overlay mechanism to add such chips to the tree, or would use > one large default device tree, and delete the devices that are actually > not present. > > Regardless of approach, even on the U-Boot level, a modification of the > device tree is a prerequisite to have such modular families of boards > supported properly. > > Therefore, we add an option to make the U-Boot device tree (the actual > copy later used by the driver model) writeable, and add a callback > method that allows boards to modify the device tree at an early stage, > at which, hopefully, also the application of device tree overlays will > be possible. > > Signed-off-by: Mario Six <mario.six@gdsys.cc> I didn't follow DT overlay lately closely especially not in U-Boot. Simon, Maxim could you please take a look at this patch and comment on its necessity? > --- > common/board_f.c | 3 +++ > dts/Kconfig | 10 ++++++++++ > include/asm-generic/global_data.h | 4 ++++ > include/common.h | 1 + > 4 files changed, 18 insertions(+) > > diff --git a/common/board_f.c b/common/board_f.c > index 4b74835..cda5aae 100644 > --- a/common/board_f.c > +++ b/common/board_f.c > @@ -1034,6 +1034,9 @@ static init_fnc_t init_sequence_f[] = { > #ifdef CONFIG_SYS_EXTBDINFO > setup_board_extra, > #endif > +#ifdef CONFIG_OF_BOARD_FIXUP > + board_fix_fdt, > +#endif > INIT_FUNC_WATCHDOG_RESET > reloc_fdt, > setup_reloc, > diff --git a/dts/Kconfig b/dts/Kconfig > index 4b7d8b1..3f64eda 100644 > --- a/dts/Kconfig > +++ b/dts/Kconfig > @@ -14,6 +14,16 @@ config OF_CONTROL > This feature provides for run-time configuration of U-Boot > via a flattened device tree. > > +config OF_BOARD_FIXUP > + bool "Board-specific manipulation of Device Tree" > + help > + In certain circumstances it is necessary to be able to modify > + U-Boot's device tree (e.g. to delete device from it). This option > + make the Device Tree writeable and provides a board-specific > + "board_fix_fdt" callback (called during pre-relocation time), which > + enables the board initialization to modifiy the Device Tree. The > + modified copy is subsequently used by U-Boot after relocation. > + > config SPL_OF_CONTROL > bool "Enable run-time configuration via Device Tree in SPL" > depends on SPL && OF_CONTROL > diff --git a/include/asm-generic/global_data.h b/include/asm-generic/global_data.h > index e02863d..f566186 100644 > --- a/include/asm-generic/global_data.h > +++ b/include/asm-generic/global_data.h > @@ -69,7 +69,11 @@ typedef struct global_data { > struct udevice *timer; /* Timer instance for Driver Model */ > #endif > > +#ifdef CONFIG_OF_BOARD_FIXUP > + void *fdt_blob; /* Our device tree, NULL if none */ > +#else > const void *fdt_blob; /* Our device tree, NULL if none */ > +#endif > void *new_fdt; /* Relocated FDT */ > unsigned long fdt_size; /* Space reserved for relocated FDT */ > struct jt_funcs *jt; /* jump table */ > diff --git a/include/common.h b/include/common.h > index a8d833b..293ce23 100644 > --- a/include/common.h > +++ b/include/common.h > @@ -502,6 +502,7 @@ extern ssize_t spi_write (uchar *, int, uchar *, int); > > /* $(BOARD)/$(BOARD).c */ > int board_early_init_f (void); > +int board_fix_fdt (void); > int board_late_init (void); > int board_postclk_init (void); /* after clocks/timebase, before env/serial */ > int board_early_init_r (void); > Thanks, Stefan
Hi, On 1 December 2016 at 01:39, Stefan Roese <sr@denx.de> wrote: > (Adding Simon and Maxim to Cc) > > On 23.11.2016 16:12, Mario Six wrote: >> >> Certain boards come in different variations by way of utilizing daughter >> boards, for example. These boards might contain additional chips, which >> are added to the main board's busses, e.g. I2C. >> >> The device tree support for such boards would either, quite naturally, >> employ the overlay mechanism to add such chips to the tree, or would use >> one large default device tree, and delete the devices that are actually >> not present. >> >> Regardless of approach, even on the U-Boot level, a modification of the >> device tree is a prerequisite to have such modular families of boards >> supported properly. >> >> Therefore, we add an option to make the U-Boot device tree (the actual >> copy later used by the driver model) writeable, and add a callback >> method that allows boards to modify the device tree at an early stage, >> at which, hopefully, also the application of device tree overlays will >> be possible. >> >> Signed-off-by: Mario Six <mario.six@gdsys.cc> > > > I didn't follow DT overlay lately closely especially not in U-Boot. > Simon, Maxim could you please take a look at this patch and comment > on its necessity? > > >> --- >> common/board_f.c | 3 +++ >> dts/Kconfig | 10 ++++++++++ >> include/asm-generic/global_data.h | 4 ++++ >> include/common.h | 1 + >> 4 files changed, 18 insertions(+) >> >> diff --git a/common/board_f.c b/common/board_f.c >> index 4b74835..cda5aae 100644 >> --- a/common/board_f.c >> +++ b/common/board_f.c >> @@ -1034,6 +1034,9 @@ static init_fnc_t init_sequence_f[] = { >> #ifdef CONFIG_SYS_EXTBDINFO >> setup_board_extra, >> #endif >> +#ifdef CONFIG_OF_BOARD_FIXUP >> + board_fix_fdt, >> +#endif Can you add documentation for this somewhere? E.g. in the driver model readme? >> INIT_FUNC_WATCHDOG_RESET >> reloc_fdt, >> setup_reloc, >> diff --git a/dts/Kconfig b/dts/Kconfig >> index 4b7d8b1..3f64eda 100644 >> --- a/dts/Kconfig >> +++ b/dts/Kconfig >> @@ -14,6 +14,16 @@ config OF_CONTROL >> This feature provides for run-time configuration of U-Boot >> via a flattened device tree. >> >> +config OF_BOARD_FIXUP >> + bool "Board-specific manipulation of Device Tree" >> + help >> + In certain circumstances it is necessary to be able to modify >> + U-Boot's device tree (e.g. to delete device from it). This >> option >> + make the Device Tree writeable and provides a board-specific >> + "board_fix_fdt" callback (called during pre-relocation time), >> which >> + enables the board initialization to modifiy the Device Tree. The >> + modified copy is subsequently used by U-Boot after relocation. >> + >> config SPL_OF_CONTROL >> bool "Enable run-time configuration via Device Tree in SPL" >> depends on SPL && OF_CONTROL >> diff --git a/include/asm-generic/global_data.h >> b/include/asm-generic/global_data.h >> index e02863d..f566186 100644 >> --- a/include/asm-generic/global_data.h >> +++ b/include/asm-generic/global_data.h >> @@ -69,7 +69,11 @@ typedef struct global_data { >> struct udevice *timer; /* Timer instance for Driver Model >> */ >> #endif >> >> +#ifdef CONFIG_OF_BOARD_FIXUP >> + void *fdt_blob; /* Our device tree, NULL if none >> */ >> +#else >> const void *fdt_blob; /* Our device tree, NULL if none >> */ >> +#endif Can we keep it as const and just use a cast when it needs to change? You could add a function which returns a writable pointer. >> void *new_fdt; /* Relocated FDT */ >> unsigned long fdt_size; /* Space reserved for relocated >> FDT */ >> struct jt_funcs *jt; /* jump table */ >> diff --git a/include/common.h b/include/common.h >> index a8d833b..293ce23 100644 >> --- a/include/common.h >> +++ b/include/common.h >> @@ -502,6 +502,7 @@ extern ssize_t spi_write (uchar *, int, uchar *, int); >> >> /* $(BOARD)/$(BOARD).c */ >> int board_early_init_f (void); >> +int board_fix_fdt (void); Comment please. Perhaps it should pass a writable fdt pointer? >> int board_late_init (void); >> int board_postclk_init (void); /* after clocks/timebase, before >> env/serial */ >> int board_early_init_r (void); There have been discussions about moving to a live tree (hierarchical format) in U-Boot post-relocation. What do you think? It might make these changes easier or more efficient. Regards, Simon
On Thu, Dec 01, 2016 at 09:39:14AM +0100, Stefan Roese wrote: > (Adding Simon and Maxim to Cc) > > On 23.11.2016 16:12, Mario Six wrote: > > Certain boards come in different variations by way of utilizing daughter > > boards, for example. These boards might contain additional chips, which > > are added to the main board's busses, e.g. I2C. > > > > The device tree support for such boards would either, quite naturally, > > employ the overlay mechanism to add such chips to the tree, or would use > > one large default device tree, and delete the devices that are actually > > not present. > > > > Regardless of approach, even on the U-Boot level, a modification of the > > device tree is a prerequisite to have such modular families of boards > > supported properly. > > > > Therefore, we add an option to make the U-Boot device tree (the actual > > copy later used by the driver model) writeable, and add a callback > > method that allows boards to modify the device tree at an early stage, > > at which, hopefully, also the application of device tree overlays will > > be possible. > > > > Signed-off-by: Mario Six <mario.six@gdsys.cc> > > I didn't follow DT overlay lately closely especially not in U-Boot. > Simon, Maxim could you please take a look at this patch and comment > on its necessity? > > > --- > > common/board_f.c | 3 +++ > > dts/Kconfig | 10 ++++++++++ > > include/asm-generic/global_data.h | 4 ++++ > > include/common.h | 1 + > > 4 files changed, 18 insertions(+) > > > > diff --git a/common/board_f.c b/common/board_f.c > > index 4b74835..cda5aae 100644 > > --- a/common/board_f.c > > +++ b/common/board_f.c > > @@ -1034,6 +1034,9 @@ static init_fnc_t init_sequence_f[] = { > > #ifdef CONFIG_SYS_EXTBDINFO > > setup_board_extra, > > #endif > > +#ifdef CONFIG_OF_BOARD_FIXUP > > + board_fix_fdt, > > +#endif > > INIT_FUNC_WATCHDOG_RESET > > reloc_fdt, > > setup_reloc, > > diff --git a/dts/Kconfig b/dts/Kconfig > > index 4b7d8b1..3f64eda 100644 > > --- a/dts/Kconfig > > +++ b/dts/Kconfig > > @@ -14,6 +14,16 @@ config OF_CONTROL > > This feature provides for run-time configuration of U-Boot > > via a flattened device tree. > > > > +config OF_BOARD_FIXUP > > + bool "Board-specific manipulation of Device Tree" > > + help > > + In certain circumstances it is necessary to be able to modify > > + U-Boot's device tree (e.g. to delete device from it). This option > > + make the Device Tree writeable and provides a board-specific > > + "board_fix_fdt" callback (called during pre-relocation time), which > > + enables the board initialization to modifiy the Device Tree. The > > + modified copy is subsequently used by U-Boot after relocation. > > + Judging from the help, I guess this is going to be applied even before the device model initialization. Since our plan is to eventually switch to the device model, and you'll probably need someway to detect which adjustments you need to make (using a GPIO, some bus, etc.) which is probably going to be backed by a device model driver. Wouldn't that introduce a chicken and egg issue? Maxime
Hi Simon, On Mon, Dec 5, 2016 at 7:24 AM, Simon Glass <sjg@chromium.org> wrote: > Hi, > > On 1 December 2016 at 01:39, Stefan Roese <sr@denx.de> wrote: >> (Adding Simon and Maxim to Cc) >> >> On 23.11.2016 16:12, Mario Six wrote: >>> >>> Certain boards come in different variations by way of utilizing daughter >>> boards, for example. These boards might contain additional chips, which >>> are added to the main board's busses, e.g. I2C. >>> >>> The device tree support for such boards would either, quite naturally, >>> employ the overlay mechanism to add such chips to the tree, or would use >>> one large default device tree, and delete the devices that are actually >>> not present. >>> >>> Regardless of approach, even on the U-Boot level, a modification of the >>> device tree is a prerequisite to have such modular families of boards >>> supported properly. >>> >>> Therefore, we add an option to make the U-Boot device tree (the actual >>> copy later used by the driver model) writeable, and add a callback >>> method that allows boards to modify the device tree at an early stage, >>> at which, hopefully, also the application of device tree overlays will >>> be possible. >>> >>> Signed-off-by: Mario Six <mario.six@gdsys.cc> >> >> >> I didn't follow DT overlay lately closely especially not in U-Boot. >> Simon, Maxim could you please take a look at this patch and comment >> on its necessity? >> >> >>> --- >>> common/board_f.c | 3 +++ >>> dts/Kconfig | 10 ++++++++++ >>> include/asm-generic/global_data.h | 4 ++++ >>> include/common.h | 1 + >>> 4 files changed, 18 insertions(+) >>> >>> diff --git a/common/board_f.c b/common/board_f.c >>> index 4b74835..cda5aae 100644 >>> --- a/common/board_f.c >>> +++ b/common/board_f.c >>> @@ -1034,6 +1034,9 @@ static init_fnc_t init_sequence_f[] = { >>> #ifdef CONFIG_SYS_EXTBDINFO >>> setup_board_extra, >>> #endif >>> +#ifdef CONFIG_OF_BOARD_FIXUP >>> + board_fix_fdt, >>> +#endif > > Can you add documentation for this somewhere? E.g. in the driver model readme? > OK, I'll document the feature in v2. >>> INIT_FUNC_WATCHDOG_RESET >>> reloc_fdt, >>> setup_reloc, >>> diff --git a/dts/Kconfig b/dts/Kconfig >>> index 4b7d8b1..3f64eda 100644 >>> --- a/dts/Kconfig >>> +++ b/dts/Kconfig >>> @@ -14,6 +14,16 @@ config OF_CONTROL >>> This feature provides for run-time configuration of U-Boot >>> via a flattened device tree. >>> >>> +config OF_BOARD_FIXUP >>> + bool "Board-specific manipulation of Device Tree" >>> + help >>> + In certain circumstances it is necessary to be able to modify >>> + U-Boot's device tree (e.g. to delete device from it). This >>> option >>> + make the Device Tree writeable and provides a board-specific >>> + "board_fix_fdt" callback (called during pre-relocation time), >>> which >>> + enables the board initialization to modifiy the Device Tree. The >>> + modified copy is subsequently used by U-Boot after relocation. >>> + >>> config SPL_OF_CONTROL >>> bool "Enable run-time configuration via Device Tree in SPL" >>> depends on SPL && OF_CONTROL >>> diff --git a/include/asm-generic/global_data.h >>> b/include/asm-generic/global_data.h >>> index e02863d..f566186 100644 >>> --- a/include/asm-generic/global_data.h >>> +++ b/include/asm-generic/global_data.h >>> @@ -69,7 +69,11 @@ typedef struct global_data { >>> struct udevice *timer; /* Timer instance for Driver Model >>> */ >>> #endif >>> >>> +#ifdef CONFIG_OF_BOARD_FIXUP >>> + void *fdt_blob; /* Our device tree, NULL if none >>> */ >>> +#else >>> const void *fdt_blob; /* Our device tree, NULL if none >>> */ >>> +#endif > > Can we keep it as const and just use a cast when it needs to change? > You could add a function which returns a writable pointer. > Having the pointer globally writable has the advantage that you can get a writable pointer wherever you need it and don't have to pass it around, but separating the parts where the pointer is writable from the ones where it is not is probably a good idea. Will fix in v2. > >>> void *new_fdt; /* Relocated FDT */ >>> unsigned long fdt_size; /* Space reserved for relocated >>> FDT */ >>> struct jt_funcs *jt; /* jump table */ >>> diff --git a/include/common.h b/include/common.h >>> index a8d833b..293ce23 100644 >>> --- a/include/common.h >>> +++ b/include/common.h >>> @@ -502,6 +502,7 @@ extern ssize_t spi_write (uchar *, int, uchar *, int); >>> >>> /* $(BOARD)/$(BOARD).c */ >>> int board_early_init_f (void); >>> +int board_fix_fdt (void); > > Comment please. Perhaps it should pass a writable fdt pointer? > I'll add a comment in v2. >>> int board_late_init (void); >>> int board_postclk_init (void); /* after clocks/timebase, before >>> env/serial */ >>> int board_early_init_r (void); > > There have been discussions about moving to a live tree (hierarchical > format) in U-Boot post-relocation. What do you think? It might make > these changes easier or more efficient. > Yes, that would definitely make things easier. The approach of modifying the tree before the main U-Boot "sees it" that I'm taking here seems a bit hacky. The other approach I've been experimenting with consisted of starting the board with a base device tree, which only has the devices in it that are guaranteed to exists, gather all needed data to decide which overlays to apply, then tear down the DM (using dm_uninit), make the modifications to the tree, and restart the DM (with dm_init_and_scan). While this worked more or less fine, it seems very wasteful, and a genuinely modifiable tree would be a much nicer solution. Also, we need a solution to this problem one way or another; the way our hardware is constructed, we need to check which devices actually exist and which do not by querying the hardware itself. And the most natural thing to do here would be to have a modifiable device tree. > Regards, > Simon >
Hi Mario, On 5 December 2016 at 10:32, Mario Six <mariosix1986@gmail.com> wrote: > Hi Simon, > > On Mon, Dec 5, 2016 at 7:24 AM, Simon Glass <sjg@chromium.org> wrote: >> Hi, >> >> On 1 December 2016 at 01:39, Stefan Roese <sr@denx.de> wrote: >>> (Adding Simon and Maxim to Cc) >>> >>> On 23.11.2016 16:12, Mario Six wrote: >>>> >>>> Certain boards come in different variations by way of utilizing daughter >>>> boards, for example. These boards might contain additional chips, which >>>> are added to the main board's busses, e.g. I2C. >>>> >>>> The device tree support for such boards would either, quite naturally, >>>> employ the overlay mechanism to add such chips to the tree, or would use >>>> one large default device tree, and delete the devices that are actually >>>> not present. >>>> >>>> Regardless of approach, even on the U-Boot level, a modification of the >>>> device tree is a prerequisite to have such modular families of boards >>>> supported properly. >>>> >>>> Therefore, we add an option to make the U-Boot device tree (the actual >>>> copy later used by the driver model) writeable, and add a callback >>>> method that allows boards to modify the device tree at an early stage, >>>> at which, hopefully, also the application of device tree overlays will >>>> be possible. >>>> >>>> Signed-off-by: Mario Six <mario.six@gdsys.cc> >>> >>> >>> I didn't follow DT overlay lately closely especially not in U-Boot. >>> Simon, Maxim could you please take a look at this patch and comment >>> on its necessity? >>> >>> >>>> --- >>>> common/board_f.c | 3 +++ >>>> dts/Kconfig | 10 ++++++++++ >>>> include/asm-generic/global_data.h | 4 ++++ >>>> include/common.h | 1 + >>>> 4 files changed, 18 insertions(+) >>>> >>>> diff --git a/common/board_f.c b/common/board_f.c >>>> index 4b74835..cda5aae 100644 >>>> --- a/common/board_f.c >>>> +++ b/common/board_f.c >>>> @@ -1034,6 +1034,9 @@ static init_fnc_t init_sequence_f[] = { >>>> #ifdef CONFIG_SYS_EXTBDINFO >>>> setup_board_extra, >>>> #endif >>>> +#ifdef CONFIG_OF_BOARD_FIXUP >>>> + board_fix_fdt, >>>> +#endif >> >> Can you add documentation for this somewhere? E.g. in the driver model readme? >> > > OK, I'll document the feature in v2. > >>>> INIT_FUNC_WATCHDOG_RESET >>>> reloc_fdt, >>>> setup_reloc, >>>> diff --git a/dts/Kconfig b/dts/Kconfig >>>> index 4b7d8b1..3f64eda 100644 >>>> --- a/dts/Kconfig >>>> +++ b/dts/Kconfig >>>> @@ -14,6 +14,16 @@ config OF_CONTROL >>>> This feature provides for run-time configuration of U-Boot >>>> via a flattened device tree. >>>> >>>> +config OF_BOARD_FIXUP >>>> + bool "Board-specific manipulation of Device Tree" >>>> + help >>>> + In certain circumstances it is necessary to be able to modify >>>> + U-Boot's device tree (e.g. to delete device from it). This >>>> option >>>> + make the Device Tree writeable and provides a board-specific >>>> + "board_fix_fdt" callback (called during pre-relocation time), >>>> which >>>> + enables the board initialization to modifiy the Device Tree. The >>>> + modified copy is subsequently used by U-Boot after relocation. >>>> + >>>> config SPL_OF_CONTROL >>>> bool "Enable run-time configuration via Device Tree in SPL" >>>> depends on SPL && OF_CONTROL >>>> diff --git a/include/asm-generic/global_data.h >>>> b/include/asm-generic/global_data.h >>>> index e02863d..f566186 100644 >>>> --- a/include/asm-generic/global_data.h >>>> +++ b/include/asm-generic/global_data.h >>>> @@ -69,7 +69,11 @@ typedef struct global_data { >>>> struct udevice *timer; /* Timer instance for Driver Model >>>> */ >>>> #endif >>>> >>>> +#ifdef CONFIG_OF_BOARD_FIXUP >>>> + void *fdt_blob; /* Our device tree, NULL if none >>>> */ >>>> +#else >>>> const void *fdt_blob; /* Our device tree, NULL if none >>>> */ >>>> +#endif >> >> Can we keep it as const and just use a cast when it needs to change? >> You could add a function which returns a writable pointer. >> > > Having the pointer globally writable has the advantage that you can get a > writable pointer wherever you need it and don't have to pass it around, but > separating the parts where the pointer is writable from the ones where it is > not is probably a good idea. Will fix in v2. > >> >>>> void *new_fdt; /* Relocated FDT */ >>>> unsigned long fdt_size; /* Space reserved for relocated >>>> FDT */ >>>> struct jt_funcs *jt; /* jump table */ >>>> diff --git a/include/common.h b/include/common.h >>>> index a8d833b..293ce23 100644 >>>> --- a/include/common.h >>>> +++ b/include/common.h >>>> @@ -502,6 +502,7 @@ extern ssize_t spi_write (uchar *, int, uchar *, int); >>>> >>>> /* $(BOARD)/$(BOARD).c */ >>>> int board_early_init_f (void); >>>> +int board_fix_fdt (void); >> >> Comment please. Perhaps it should pass a writable fdt pointer? >> > > I'll add a comment in v2. > >>>> int board_late_init (void); >>>> int board_postclk_init (void); /* after clocks/timebase, before >>>> env/serial */ >>>> int board_early_init_r (void); >> >> There have been discussions about moving to a live tree (hierarchical >> format) in U-Boot post-relocation. What do you think? It might make >> these changes easier or more efficient. >> > > Yes, that would definitely make things easier. The approach of modifying the > tree before the main U-Boot "sees it" that I'm taking here seems a bit hacky. > The other approach I've been experimenting with consisted of starting the board > with a base device tree, which only has the devices in it that are guaranteed > to exists, gather all needed data to decide which overlays to apply, then tear > down the DM (using dm_uninit), make the modifications to the tree, and restart > the DM (with dm_init_and_scan). While this worked more or less fine, it seems > very wasteful, and a genuinely modifiable tree would be a much nicer solution. > > Also, we need a solution to this problem one way or another; the way our > hardware is constructed, we need to check which devices actually exist and > which do not by querying the hardware itself. And the most natural thing to do > here would be to have a modifiable device tree. Creating a live tree is pretty easy - perhaps 500 lines of code. Trickier is to adjust the existing fdtdec API so that you can pass a node pointer instead of a blob and offset. I suppose we need to support the existing API for a while. I think ideally we should have a flat tree before relocation (to save time and space) and a live tree afterwards. So your approach of making the flip just before relocation seems right to me. Regards, Simon
diff --git a/common/board_f.c b/common/board_f.c index 4b74835..cda5aae 100644 --- a/common/board_f.c +++ b/common/board_f.c @@ -1034,6 +1034,9 @@ static init_fnc_t init_sequence_f[] = { #ifdef CONFIG_SYS_EXTBDINFO setup_board_extra, #endif +#ifdef CONFIG_OF_BOARD_FIXUP + board_fix_fdt, +#endif INIT_FUNC_WATCHDOG_RESET reloc_fdt, setup_reloc, diff --git a/dts/Kconfig b/dts/Kconfig index 4b7d8b1..3f64eda 100644 --- a/dts/Kconfig +++ b/dts/Kconfig @@ -14,6 +14,16 @@ config OF_CONTROL This feature provides for run-time configuration of U-Boot via a flattened device tree. +config OF_BOARD_FIXUP + bool "Board-specific manipulation of Device Tree" + help + In certain circumstances it is necessary to be able to modify + U-Boot's device tree (e.g. to delete device from it). This option + make the Device Tree writeable and provides a board-specific + "board_fix_fdt" callback (called during pre-relocation time), which + enables the board initialization to modifiy the Device Tree. The + modified copy is subsequently used by U-Boot after relocation. + config SPL_OF_CONTROL bool "Enable run-time configuration via Device Tree in SPL" depends on SPL && OF_CONTROL diff --git a/include/asm-generic/global_data.h b/include/asm-generic/global_data.h index e02863d..f566186 100644 --- a/include/asm-generic/global_data.h +++ b/include/asm-generic/global_data.h @@ -69,7 +69,11 @@ typedef struct global_data { struct udevice *timer; /* Timer instance for Driver Model */ #endif +#ifdef CONFIG_OF_BOARD_FIXUP + void *fdt_blob; /* Our device tree, NULL if none */ +#else const void *fdt_blob; /* Our device tree, NULL if none */ +#endif void *new_fdt; /* Relocated FDT */ unsigned long fdt_size; /* Space reserved for relocated FDT */ struct jt_funcs *jt; /* jump table */ diff --git a/include/common.h b/include/common.h index a8d833b..293ce23 100644 --- a/include/common.h +++ b/include/common.h @@ -502,6 +502,7 @@ extern ssize_t spi_write (uchar *, int, uchar *, int); /* $(BOARD)/$(BOARD).c */ int board_early_init_f (void); +int board_fix_fdt (void); int board_late_init (void); int board_postclk_init (void); /* after clocks/timebase, before env/serial */ int board_early_init_r (void);
Certain boards come in different variations by way of utilizing daughter boards, for example. These boards might contain additional chips, which are added to the main board's busses, e.g. I2C. The device tree support for such boards would either, quite naturally, employ the overlay mechanism to add such chips to the tree, or would use one large default device tree, and delete the devices that are actually not present. Regardless of approach, even on the U-Boot level, a modification of the device tree is a prerequisite to have such modular families of boards supported properly. Therefore, we add an option to make the U-Boot device tree (the actual copy later used by the driver model) writeable, and add a callback method that allows boards to modify the device tree at an early stage, at which, hopefully, also the application of device tree overlays will be possible. Signed-off-by: Mario Six <mario.six@gdsys.cc> --- common/board_f.c | 3 +++ dts/Kconfig | 10 ++++++++++ include/asm-generic/global_data.h | 4 ++++ include/common.h | 1 + 4 files changed, 18 insertions(+)