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Date: Tue, 9 Oct 2018 11:02:29 -0700
From: Frank Rowand <frowand.list@...il.com>
To: "AKASHI, Takahiro" <takahiro.akashi@...aro.org>,
Rob Herring <robh+dt@...nel.org>,
David Gibson <david@...son.dropbear.id.au>,
Catalin Marinas <catalin.marinas@....com>,
Will Deacon <will.deacon@....com>,
David Howells <dhowells@...hat.com>,
Vivek Goyal <vgoyal@...hat.com>,
Herbert Xu <herbert@...dor.apana.org.au>,
David Miller <davem@...emloft.net>, dyoung@...hat.com,
Baoquan He <bhe@...hat.com>, Arnd Bergmann <arnd@...db.de>,
Martin Schwidefsky <schwidefsky@...ibm.com>,
Heiko Carstens <heiko.carstens@...ibm.com>,
prudo@...ux.ibm.com, Ard Biesheuvel <ard.biesheuvel@...aro.org>,
James Morse <james.morse@....com>, bhsharma@...hat.com,
kexec@...ts.infradead.org,
"moderated list:ARM/FREESCALE IMX / MXC ARM ARCHITECTURE"
<linux-arm-kernel@...ts.infradead.org>,
"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
devicetree@...r.kernel.org
Subject: Re: [PATCH v15 06/16] of/fdt: add helper functions for handling
properties
On 10/04/18 22:06, AKASHI, Takahiro wrote:
> Frank,
>
> # I haven't reply to your comments.
>
> On Fri, Sep 28, 2018 at 02:13:58PM -0700, Frank Rowand wrote:
>> On 09/28/18 06:44, Rob Herring wrote:
>>> +David Gibson
>>>
>>> On Fri, Sep 28, 2018 at 1:48 AM AKASHI Takahiro
>>> <takahiro.akashi@...aro.org> wrote:
>>>>
>>>> These functions will be used later to handle kexec-specific properties
>>>> in arm64's kexec_file implementation.
>>
>> As I requested in version 14:
>>
>> The intent of the helper functions is related to properties whose values are
>> tuples of the same format as the "reg" property of the "/memory" nodes. For
>> example, the "linux,usable-memory-range" and "linux,elfcoredhr" properties of
>> the "/chosen" node.
>>
>> The patch header and the function names should be updated to reflect this intent.
>
> I agree regarding the patch header.
>
>>
>>>>
>>>> Signed-off-by: AKASHI Takahiro <takahiro.akashi@...aro.org>
>>>> Cc: Rob Herring <robh+dt@...nel.org>
>>>> Cc: Frank Rowand <frowand.list@...il.com>
>>>> Cc: devicetree@...r.kernel.org
>>>> ---
>>
>> Missing list of changes since version 14.
>
> Sorry for the inconvenience, but a whole change list goes into
> the cover letter, not individual patches.
That works for me, but please add us to the distro list for the cover letter.
>>>> drivers/of/fdt.c | 56 ++++++++++++++++++++++++++++++++++++++++++
>>>> include/linux/of_fdt.h | 4 +++
>>>> 2 files changed, 60 insertions(+)
>>>>
>>>> diff --git a/drivers/of/fdt.c b/drivers/of/fdt.c
>>>> index 800ad252cf9c..c65c31562ccb 100644
>>>> --- a/drivers/of/fdt.c
>>>> +++ b/drivers/of/fdt.c
>>>> @@ -25,6 +25,7 @@
>>>> #include <linux/debugfs.h>
>>>> #include <linux/serial_core.h>
>>>> #include <linux/sysfs.h>
>>>> +#include <linux/types.h>
>>>>
>>>> #include <asm/setup.h> /* for COMMAND_LINE_SIZE */
>>>> #include <asm/page.h>
>>>> @@ -1323,3 +1324,58 @@ late_initcall(of_fdt_raw_init);
>>>> #endif
>>>>
>>>> #endif /* CONFIG_OF_EARLY_FLATTREE */
>>
>> In v14 I requested:
>>
>> Please add comment:
>>
>> /* helper functions for arm64 kexec */
>
> Okay.
>
>>
>>>> +
>>>> +#define FDT_ALIGN(x, a) (((x) + (a) - 1) & ~((a) - 1))
>>>> +#define FDT_TAGALIGN(x) (FDT_ALIGN((x), FDT_TAGSIZE))
>>>> +
>>>> +int fdt_prop_len(const char *prop_name, int len)
>>
>> In v14, I requested:
>>
>> Please rename as fdt_len_added_prop()
>
> Anyhow, I will drop this function, preferring to new
> fdt_[address|size]_cells().
>
>> I'm not really happy with my suggested name, but do not have a
>> better one yet. As Rob notes, maybe David G will have a helpful
>> comment.
>>
>>>> +{
>>>> + return (strlen(prop_name) + 1) +
>>>> + sizeof(struct fdt_property) +
>>>> + FDT_TAGALIGN(len);
>>>
>>> Looks like you are using this to calculate how much space you need to
>>> allocate in addition to the current DTB for a couple of new or
>>> replaced properties. I'm not sure that this calculation is completely
>>> accurate. And it is strange there doesn't seem to be any libfdt
>>> function for this already. It would be simpler to just add some fixed
>>> additional amount.
>>>
>>> Maybe David G has comments on this?
>
> I'm not quit sure why it's not that accurate, but as I said in a reply to
> David's comment, I will take your suggestion.
>
>>>> +}
>>>> +
>>>
>>> The rest of this should go in drivers/of/fdt_address.c. Ultimately, it
>>> should go into libfdt, but I'm fine with having it in the kernel for
>>> now.
>>>
>>>> +static void fill_property(void *buf, u64 val64, int cells)
>>
>> In v14 I requested:
>>
>> Please rename as cpu64_to_fdt_cells()
>
> I don't mind, but this function may be dropped if Rob sticks to
> u-boot's fdt_pack_reg() over my fdt_setprop_reg().
I have another comment a couple of minutes ago in the longer thread
about this function.
>>
>>>> +{
>>>> + __be32 val32;
>>>> +
>>>> + while (cells) {
>>>> + val32 = cpu_to_fdt32((val64 >> (32 * (--cells))) & U32_MAX);
>>>> + memcpy(buf, &val32, sizeof(val32));
>>>> + buf += sizeof(val32);
>>>
>>> This is kind of hard to read. I would copy u-boot's fdt_pack_reg function.
>>>
>>> BTW, for purposes of moving to libfdt, we'll need the authors'
>>> (Masahiro Yamada and Hans de Goede) permission to dual license.
>>>
>>>> + }
>>>> +}
>>>> +
>>>> +int fdt_setprop_reg(void *fdt, int nodeoffset, const char *name,
>>>> + u64 addr, u64 size)
>>>> +{
>>>> + int addr_cells, size_cells;
>>
>> unsigned
>
> fdt_[address|size]_cell() returns an int.
I stand corrected. They take advantage of the fact that valid values
are in the range 0..4 and return a negative value for error.
>>>> + char buf[sizeof(__be32) * 2 * 2];
>>>> + /* assume dt_root_[addr|size]_cells <= 2 */
>>>> + void *prop;
>>>> + size_t buf_size;
>>>> +
>>>> + addr_cells = fdt_address_cells(fdt, 0);
>>>> + if (addr_cells < 0)
>>>> + return addr_cells;
>>>> + size_cells = fdt_size_cells(fdt, 0);
>>>> + if (size_cells < 0)
>>>> + return size_cells;
>>>> +
>>>> + /* if *_cells >= 2, cells can hold 64-bit values anyway */
>>>> + if ((addr_cells == 1) && (addr > U32_MAX))
>>>> + return -FDT_ERR_BADVALUE;
>>>> +
>>>> + if ((size_cells == 1) && (size > U32_MAX))
>>>> + return -FDT_ERR_BADVALUE;
>>
>> In v14 I requested:
>>
>> Should also check that base + size does not wrap around.
>
> Okay, I will start discussion, as you have suggested, in devicetree-spec ML.
>
> Thanks,
> -Takahiro Akashi
>
>>
>>>> +
>>>> + buf_size = (addr_cells + size_cells) * sizeof(u32);
>>>> + prop = buf;
>>>> +
>>>> + fill_property(prop, addr, addr_cells);
>>>> + prop += addr_cells * sizeof(u32);
>>>> +
>>>> + fill_property(prop, size, size_cells);
>>>> +
>>>> + return fdt_setprop(fdt, nodeoffset, name, buf, buf_size);
>>>> +}
>>>> diff --git a/include/linux/of_fdt.h b/include/linux/of_fdt.h
>>>> index b9cd9ebdf9b9..842af6ea92ea 100644
>>>> --- a/include/linux/of_fdt.h
>>>> +++ b/include/linux/of_fdt.h
>>>> @@ -108,5 +108,9 @@ static inline void unflatten_device_tree(void) {}
>>>> static inline void unflatten_and_copy_device_tree(void) {}
>>>> #endif /* CONFIG_OF_EARLY_FLATTREE */
>>>>
>>>> +int fdt_prop_len(const char *prop_name, int len);
>>>> +int fdt_setprop_reg(void *fdt, int nodeoffset, const char *name,
>>>> + u64 addr, u64 size);
>>>> +
>>>> #endif /* __ASSEMBLY__ */
>>>> #endif /* _LINUX_OF_FDT_H */
>>>> --
>>>> 2.19.0
>>>>
>>>
>>
>
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