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Date: Fri, 28 Sep 2018 14:13:58 -0700
From: Frank Rowand <frowand.list@...il.com>
To: Rob Herring <robh+dt@...nel.org>,
"AKASHI, Takahiro" <takahiro.akashi@...aro.org>,
David Gibson <david@...son.dropbear.id.au>
Cc: 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 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.
>>
>> 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.
>> 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 */
>> +
>> +#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()
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?
>
>> +}
>> +
>
> 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()
>> +{
>> + __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
>> + 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.
>> +
>> + 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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