linux-kernel - Re: [RFC PATCH v2 02/12] of: Allow scripts/dtc/libfdt to be used from kernel code

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Message-ID: <AANLkTimHkOuO=wyyBNiPeMCq=JYMmT0_fsZ00yyDNNJn@mail.gmail.com>
Date:	Fri, 4 Mar 2011 17:59:27 -0700
From:	Grant Likely <grant.likely@...retlab.ca>
To:	David Daney <ddaney@...iumnetworks.com>
Cc:	linux-mips@...ux-mips.org, ralf@...ux-mips.org,
	devicetree-discuss@...ts.ozlabs.org, linux-kernel@...r.kernel.org,
	David Gibson <dwg@....ibm.com>
Subject: Re: [RFC PATCH v2 02/12] of: Allow scripts/dtc/libfdt to be used from
 kernel code

[actually cc'ing David Gibson this time]

On Fri, Mar 4, 2011 at 5:57 PM, Grant Likely <grant.likely@...retlab.ca> wrote:
> [cc'ing David Gibson]
> On Fri, Mar 04, 2011 at 11:42:14AM -0800, David Daney wrote:
>> Signed-off-by: David Daney <ddaney@...iumnetworks.com>
>> ---
>>  include/linux/libfdt.h      |    3 +++
>>  lib/Kconfig                 |    6 ++++++
>>  lib/Makefile                |    2 ++
>>  lib/libfdt/Makefile         |    7 +++++++
>>  lib/libfdt/libfdt_env.h     |   21 +++++++++++++++++++++
>>  scripts/dtc/libfdt/libfdt.h |    4 ++--
>>  6 files changed, 41 insertions(+), 2 deletions(-)
>>  create mode 100644 include/linux/libfdt.h
>>  create mode 100644 lib/libfdt/Makefile
>>  create mode 100644 lib/libfdt/libfdt_env.h
>>
>> diff --git a/include/linux/libfdt.h b/include/linux/libfdt.h
>> new file mode 100644
>> index 0000000..10bce91
>> --- /dev/null
>> +++ b/include/linux/libfdt.h
>> @@ -0,0 +1,3 @@
>> +#include "../../lib/libfdt/libfdt_env.h"
>
> libfdt_env.h should be in include/linux
>
>> +#include "../../scripts/dtc/libfdt/fdt.h"
>> +#include "../../scripts/dtc/libfdt/libfdt.h"
>
> Hmmm... I wonder if there is a better way to do this.  I don't much
> care for the relative path references.
>
> Also, need to have #ifdef _INCLUDE_LIBFDT_H_ protection
>
>> diff --git a/lib/Kconfig b/lib/Kconfig
>> index 0ee67e0..e8a2638 100644
>> --- a/lib/Kconfig
>> +++ b/lib/Kconfig
>> @@ -219,4 +219,10 @@ config LRU_CACHE
>>  config AVERAGE
>>       bool
>>
>> +#
>> +# The Flattened Device Tree manipulation library
>> +#
>> +config LIBFDT
>> +     bool
>> +
>
> This should be in drivers/of/Kconfig
>
>>  endmenu
>> diff --git a/lib/Makefile b/lib/Makefile
>> index cbb774f..5840115 100644
>> --- a/lib/Makefile
>> +++ b/lib/Makefile
>> @@ -110,6 +110,8 @@ obj-$(CONFIG_ATOMIC64_SELFTEST) += atomic64_test.o
>>
>>  obj-$(CONFIG_AVERAGE) += average.o
>>
>> +obj-$(CONFIG_LIBFDT) += libfdt/
>> +
>
> Ditto here; drivers/of/libfdt
>
>>  hostprogs-y  := gen_crc32table
>>  clean-files  := crc32table.h
>>
>> diff --git a/lib/libfdt/Makefile b/lib/libfdt/Makefile
>> new file mode 100644
>> index 0000000..6c1a496
>> --- /dev/null
>> +++ b/lib/libfdt/Makefile
>> @@ -0,0 +1,7 @@
>> +obj-y = fdt.o fdt_wip.o fdt_ro.o
>> +
>> +EXTRA_CFLAGS += -include $(src)/libfdt_env.h -I$(src)/../../scripts/dtc/libfdt
>> +
>> +$(obj)/%.o: $(src)/../../scripts/dtc/libfdt/%.c FORCE
>> +     $(call cmd,force_checksrc)
>> +     $(call if_changed_rule,cc_o_c)
>> diff --git a/lib/libfdt/libfdt_env.h b/lib/libfdt/libfdt_env.h
>> new file mode 100644
>> index 0000000..d977b8b
>> --- /dev/null
>> +++ b/lib/libfdt/libfdt_env.h
>> @@ -0,0 +1,21 @@
>> +#ifndef _LIBFDT_ENV_H
>> +#define _LIBFDT_ENV_H
>> +
>> +#include <linux/string.h>
>> +
>> +#define _B(n)        ((unsigned long long)((uint8_t *)&x)[n])
>> +static inline uint32_t fdt32_to_cpu(uint32_t x)
>> +{
>> +     return (_B(0) << 24) | (_B(1) << 16) | (_B(2) << 8) | _B(3);
>> +}
>> +#define cpu_to_fdt32(x) fdt32_to_cpu(x)
>> +
>> +static inline uint64_t fdt64_to_cpu(uint64_t x)
>> +{
>> +     return (_B(0) << 56) | (_B(1) << 48) | (_B(2) << 40) | (_B(3) << 32)
>> +             | (_B(4) << 24) | (_B(5) << 16) | (_B(6) << 8) | _B(7);
>> +}
>> +#define cpu_to_fdt64(x) fdt64_to_cpu(x)
>> +#undef _B
>> +
>
> This isn't necessary, the kernel already has efficient architecture
> macros for converting endianess.
>
> #define fdt32_to_cpu(x) be32_to_cpu(x)
> #define cpu_to_fdt32(x) cpu_to_be32(x)
> #define fdt64_to_cpu(x) be64_to_cpu(x)
> #define cpu_to_fdt64(x) cpu_to_be64(x)
>
>> +#endif /* _LIBFDT_ENV_H */
>> diff --git a/scripts/dtc/libfdt/libfdt.h b/scripts/dtc/libfdt/libfdt.h
>> index ce80e4f..33a0c4d 100644
>> --- a/scripts/dtc/libfdt/libfdt.h
>> +++ b/scripts/dtc/libfdt/libfdt.h
>> @@ -51,8 +51,8 @@
>>   *     EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
>>   */
>>
>> -#include <libfdt_env.h>
>> -#include <fdt.h>
>> +#include "libfdt_env.h"
>> +#include "fdt.h"
>
> This causes problems.  libfdt is an external library that is
> periodically copied into the kernel tree.  It would be better to add
> "-Iscripts/dtc/libfdt" to CFLAGS for .c files that want to call libfdt
> routines.
>
>>
>>  #define FDT_FIRST_SUPPORTED_VERSION  0x10
>>  #define FDT_LAST_SUPPORTED_VERSION   0x11
>> --
>> 1.7.2.3
>>
>



-- 
Grant Likely, B.Sc., P.Eng.
Secret Lab Technologies Ltd.
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