amlogic mmc_partitions support

amlogic mmc_partitions support

[Andreas Fenkart]

Hi,

What is a feasible way to port the vendor supplied
drivers/amlogic/mmc/emmc_partitions.c into something that could be
mainlined? My thought is to create a custom block/partition/amlogic.c
driver. Would that have a chance to be included in mainline?

Anybody else that tries to support the existing amlogic partition
format, not the implementation, as is. I want to upgrade the kernel
via fw upgrade on existing installations, but not touch the u-boot nor
the formatting.

/Andi

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Re: amlogic mmc_partitions support

[Neil Armstrong]

Hi Andreas,

On 14/01/2019 10:54, Andreas Fenkart wrote:
> Hi,
> 
> What is a feasible way to port the vendor supplied
> drivers/amlogic/mmc/emmc_partitions.c into something that could be
> mainlined? My thought is to create a custom block/partition/amlogic.c
> driver. Would that have a chance to be included in mainline?

Basically, Amlogic uses the eMMC main partition as a MTD devices and uses a
custom DT partition scheme to export named MTD partitions to user-space.

They don't use any "standard" partitions schemes on the eMMC main HW partition.

Mainline will never support DT-defined MMC partitions, and will never support
a MTD indirection to a MMC HW partition either.

You can try to implement something similar using FUSE, but it won't be simple.

> 
> Anybody else that tries to support the existing amlogic partition
> format, not the implementation, as is. I want to upgrade the kernel
> via fw upgrade on existing installations, but not touch the u-boot nor
> the formatting.

Some people forward ported it, and is available on some git repos around the
Khadas VIM support.

Neil

> 
> /Andi
> 
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> 


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Re: amlogic mmc_partitions support

[Peter Korsgaard]

>>>>> "Neil" == Neil Armstrong <narmstrong@baylibre.com> writes:

 > Hi Andreas,
 > On 14/01/2019 10:54, Andreas Fenkart wrote:
 >> Hi,
 >> 
 >> What is a feasible way to port the vendor supplied
 >> drivers/amlogic/mmc/emmc_partitions.c into something that could be
 >> mainlined? My thought is to create a custom block/partition/amlogic.c
 >> driver. Would that have a chance to be included in mainline?

 > Basically, Amlogic uses the eMMC main partition as a MTD devices and uses a
 > custom DT partition scheme to export named MTD partitions to user-space.

 > They don't use any "standard" partitions schemes on the eMMC main HW partition.

 > Mainline will never support DT-defined MMC partitions, and will never support
 > a MTD indirection to a MMC HW partition either.

 > You can try to implement something similar using FUSE, but it won't be simple.

Not knowing anything about the vendor driver, if this is just about
splitting up a single eMMC partition in sub blocks and not about MTD,
then this can be easily done with the dm-linear target of device mapper,
E.G. something like:

dmsetup create FOO --table "0 <size> linear /dev/mmcblk0 <offset>"

-- 
Bye, Peter Korsgaard

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Re: amlogic mmc_partitions support

[Andreas Fenkart]

Hi Neil,

Am Mo., 14. Jan. 2019 um 11:00 Uhr schrieb Neil Armstrong
<narmstrong@baylibre.com>:
>
>
> Basically, Amlogic uses the eMMC main partition as a MTD devices and uses a
> custom DT partition scheme to export named MTD partitions to user-space.

I've seen the dt section about partitions, but the partition table is
also stored on the emmc.
It's at an offset (36 MB) and uses a custom c struct.

#define     MAX_MMC_PART_NUM                32

struct partitions {
    /* identifier string */
    char name[MAX_PART_NAME_LEN];
    /* partition size, byte unit */
    uint64_t size;
    /* offset within the master space, byte unit */
    uint64_t offset;
    /* master flags to mask out for this partition */
    unsigned mask_flags;
};

struct mmc_partitions_fmt {
    char magic[4];
    unsigned char version[12];
    int part_num;
    int checksum;
    struct partitions partitions[MAX_MMC_PART_NUM];
};

I'm trying to create a prototype. Is this something that could be
mainlined then?

> > Anybody else that tries to support the existing amlogic partition
> > format, not the implementation, as is. I want to upgrade the kernel
> > via fw upgrade on existing installations, but not touch the u-boot nor
> > the formatting.
>
> Some people forward ported it, and is available on some git repos around the
> Khadas VIM support.

thanks,

/Andi

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Re: amlogic mmc_partitions support

[Neil Armstrong]

Hi Peter,

On 14/01/2019 15:35, Peter Korsgaard wrote:
>>>>>> "Neil" == Neil Armstrong <narmstrong@baylibre.com> writes:
> 
>  > Hi Andreas,
>  > On 14/01/2019 10:54, Andreas Fenkart wrote:
>  >> Hi,
>  >> 
>  >> What is a feasible way to port the vendor supplied
>  >> drivers/amlogic/mmc/emmc_partitions.c into something that could be
>  >> mainlined? My thought is to create a custom block/partition/amlogic.c
>  >> driver. Would that have a chance to be included in mainline?
> 
>  > Basically, Amlogic uses the eMMC main partition as a MTD devices and uses a
>  > custom DT partition scheme to export named MTD partitions to user-space.
> 
>  > They don't use any "standard" partitions schemes on the eMMC main HW partition.
> 
>  > Mainline will never support DT-defined MMC partitions, and will never support
>  > a MTD indirection to a MMC HW partition either.
> 
>  > You can try to implement something similar using FUSE, but it won't be simple.
> 
> Not knowing anything about the vendor driver, if this is just about
> splitting up a single eMMC partition in sub blocks and not about MTD,
> then this can be easily done with the dm-linear target of device mapper,
> E.G. something like:
> 
> dmsetup create FOO --table "0 <size> linear /dev/mmcblk0 <offset>"
> 

Indeed, it would help, thanks for the pointer.

Andreas, this should be done from user-space in an initramfs code right before
switching root to the legacy userspace, for example, nothing in the kernel will
be accepted to do that.

Neil

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