[RFC 07/22] dm: blk: add UCLASS_PARTITION

[Heinrich Schuchardt]

On 10/11/21 16:54, Simon Glass wrote:
> Hi Takahiro,
>
> On Sun, 10 Oct 2021 at 20:29, AKASHI Takahiro
> <takahiro.akashi at linaro.org> wrote:
>>
>> Heinrich,
>>
>> On Fri, Oct 08, 2021 at 10:23:52AM +0200, Heinrich Schuchardt wrote:
>>>
>>>
>>> On 10/8/21 02:51, AKASHI Takahiro wrote:
>>>> On Mon, Oct 04, 2021 at 12:27:59PM +0900, AKASHI Takahiro wrote:
>>>>> On Fri, Oct 01, 2021 at 11:30:37AM +0200, Heinrich Schuchardt wrote:
>>>>>>
>>>>>>
>>>>>> On 10/1/21 07:01, AKASHI Takahiro wrote:
>>>>>>> UCLASS_PARTITION device will be created as a child node of
>>>>>>> UCLASS_BLK device.
>>>>>>>
>>>>>>> Signed-off-by: AKASHI Takahiro <takahiro.akashi at linaro.org>
>>>>>>> ---
>>>>>>>     drivers/block/blk-uclass.c | 111 +++++++++++++++++++++++++++++++++++++
>>>>>>>     include/blk.h              |   9 +++
>>>>>>>     include/dm/uclass-id.h     |   1 +
>>>>>>>     3 files changed, 121 insertions(+)
>>>>>>>
>>>>>>> diff --git a/drivers/block/blk-uclass.c b/drivers/block/blk-uclass.c
>>>>>>> index 83682dcc181a..dd7f3c0fe31e 100644
>>>>>>> --- a/drivers/block/blk-uclass.c
>>>>>>> +++ b/drivers/block/blk-uclass.c
>>>>>>> @@ -12,6 +12,7 @@
>>>>>>>     #include <log.h>
>>>>>>>     #include <malloc.h>
>>>>>>>     #include <part.h>
>>>>>>> +#include <string.h>
>>>>>>>     #include <dm/device-internal.h>
>>>>>>>     #include <dm/lists.h>
>>>>>>>     #include <dm/uclass-internal.h>
>>>>>>> @@ -695,6 +696,44 @@ int blk_unbind_all(int if_type)
>>>>>>>        return 0;
>>>>>>>     }
>>>>>>>
>>>>>>> +int blk_create_partitions(struct udevice *parent)
>>>>>>> +{
>>>>>>> +     int part, count;
>>>>>>> +     struct blk_desc *desc = dev_get_uclass_plat(parent);
>>>>>>> +     struct disk_partition info;
>>>>>>> +     struct disk_part *part_data;
>>>>>>> +     char devname[32];
>>>>>>> +     struct udevice *dev;
>>>>>>> +     int ret;
>>>>>>> +
>>>>>>> +     if (!CONFIG_IS_ENABLED(PARTITIONS) ||
>>>>>>> +         !CONFIG_IS_ENABLED(HAVE_BLOCK_DEVICE))
>>>>>>> +             return 0;
>>>>>>> +
>>>>>>> +     /* Add devices for each partition */
>>>>>>> +     for (count = 0, part = 1; part <= MAX_SEARCH_PARTITIONS; part++) {
>>>>>>> +             if (part_get_info(desc, part, &info))
>>>>>>> +                     continue;
>>>>>>> +             snprintf(devname, sizeof(devname), "%s:%d", parent->name,
>>>>>>> +                      part);
>>>>>>> +
>>>>>>> +             ret = device_bind_driver(parent, "blk_partition",
>>>>>>> +                                      strdup(devname), &dev);
>>>>>>> +             if (ret)
>>>>>>> +                     return ret;
>>>>>>> +
>>>>>>> +             part_data = dev_get_uclass_plat(dev);
>>>>>>> +             part_data->partnum = part;
>>>>>>> +             part_data->gpt_part_info = info;
>>>>>>> +             count++;
>>>>>>> +
>>>>>>> +             device_probe(dev);
>>>>>>> +     }
>>>>>>> +     debug("%s: %d partitions found in %s\n", __func__, count, parent->name);
>>>>>>> +
>>>>>>> +     return 0;
>>>>>>> +}
>>>>>>> +
>>>>>>>     static int blk_post_probe(struct udevice *dev)
>>>>>>>     {
>>>>>>>        if (IS_ENABLED(CONFIG_PARTITIONS) &&
>>>>>>> @@ -713,3 +752,75 @@ UCLASS_DRIVER(blk) = {
>>>>>>>        .post_probe     = blk_post_probe,
>>>>>>>        .per_device_plat_auto   = sizeof(struct blk_desc),
>>>>>>>     };
>>>>>>> +
>>>>>>> +static ulong blk_part_read(struct udevice *dev, lbaint_t start,
>>>>>>> +                        lbaint_t blkcnt, void *buffer)
>>>>>>> +{
>>>>>>> +     struct udevice *parent;
>>>>>>> +     struct disk_part *part;
>>>>>>> +     const struct blk_ops *ops;
>>>>>>> +
>>>>>>> +     parent = dev_get_parent(dev);
>>>>>>
>>>>>> What device type will the parent have if it is a eMMC hardware partition?
>>>>>>
>>>>>>> +     ops = blk_get_ops(parent);
>>>>>>> +     if (!ops->read)
>>>>>>> +             return -ENOSYS;
>>>>>>> +
>>>>>>> +     part = dev_get_uclass_plat(dev);
>>>>>>
>>>>>> You should check that we do not access the block device past the
>>>>>> partition end:
>>>>>
>>>>> Yes, I will fix all of checks.
>>>>>
>>>>>> struct blk_desc *desc = dev_get_uclass_plat(parent);
>>>>>> if ((start + blkcnt) * desc->blksz < part->gpt_part_info.blksz)
>>>>>>          return -EFAULT.
>>>>>>
>>>>>>> +     start += part->gpt_part_info.start;
>>>>
>>>> A better solution is:
>>>>           if (start >= part->gpt_part_info.size)
>>>>                   return 0;
>>>>
>>>>           if ((start + blkcnt) > part->gpt_part_info.size)
>>>>                   blkcnt = part->gpt_part_info.size - start;
>>>>           start += part->gpt_part_info.start;
>>>> instead of returning -EFAULT.
>>>> (note that start and blkcnt are in "block".)
>>>
>>> What is your motivation to support an illegal access?
>>>
>>> We will implement the EFI_BLOCK_IO_PROTOCOL based on this function. The
>>> ReadBlocks() and WriteBlocks() services must return
>>> EFI_INVALID_PARAMETER if the read request contains LBAs that are not
>>> valid.
>>
>> I interpreted that 'LBA' was the third parameter to ReadBlocks API,
>> and that if the starting block is out of partition region, we should
>> return an error (and if not, we still want to trim IO request to fit
>> into partition size as other OS's API like linux does).
>> Do you think it's incorrect?
>
> [..]
>
> Related to this patch I think that the partition type should be really
> be a child of the media device:
>
> - MMC
>      |- BLK
>      |- PARTITION
>         |- BLK
>      |- PARTITION
>         |- BLK
>      |- PARTITION
>         |- BLK
>
> It seems more natural to me that putting the partitions under the
> top-level BLK device, so that BLK remains a 'terminal' device.
>
> The partition uclass is different from BLK, of course. It could
> contain information about the partition such as its partition number
> and UUID.

Do you mean hardware partition here? Otherwise I would not know what BLK
should model.

Best regards

Heinrich