[U-Boot] [PATCH 1/3] dm: blk: Add a way to obtain a block device from its parent

[Jaehoon Chung]

Hi Simon,

On 05/28/2017 02:37 AM, Simon Glass wrote:
> Many devices support a child block device (e.g. MMC, USB). Add a
> convenient way to get this device given the parent device.
> 
> Signed-off-by: Simon Glass <sjg at chromium.org>
> ---
> 
>  drivers/block/blk-uclass.c | 26 ++++++++++++++++++++++++++
>  include/blk.h              |  7 +++++++
>  test/dm/blk.c              | 18 ++++++++++++++++++
>  3 files changed, 51 insertions(+)
> 
> diff --git a/drivers/block/blk-uclass.c b/drivers/block/blk-uclass.c
> index 6145675271..23f131b7ad 100644
> --- a/drivers/block/blk-uclass.c
> +++ b/drivers/block/blk-uclass.c
> @@ -453,6 +453,32 @@ int blk_prepare_device(struct udevice *dev)
>  	return 0;
>  }
>  
> +int blk_get_from_parent(struct udevice *parent, struct udevice **devp)
> +{
> +	struct udevice *dev;
> +	enum uclass_id id;
> +	int ret;
> +
> +	device_find_first_child(parent, &dev);
> +	if (!dev) {
> +		debug("%s: No block device found for parent '%s'\n", __func__,
> +		      parent->name);
> +		return -ENODEV;
> +	}
> +	id = device_get_uclass_id(dev);
> +	if (id != UCLASS_BLK) {
> +		debug("%s: Incorrect uclass %s for block device '%s'\n",
> +		      __func__, uclass_get_name(id), dev->name);
> +		return -ENOTBLK;
> +	}
> +	ret = device_probe(dev);
> +	if (ret)
> +		return ret;
> +	*devp = dev;
> +
> +	return 0;
> +}
> +
>  int blk_find_max_devnum(enum if_type if_type)
>  {
>  	struct udevice *dev;
> diff --git a/include/blk.h b/include/blk.h
> index a128ee4841..4d60987f61 100644
> --- a/include/blk.h
> +++ b/include/blk.h
> @@ -616,4 +616,11 @@ ulong blk_write_devnum(enum if_type if_type, int devnum, lbaint_t start,
>   */
>  int blk_select_hwpart_devnum(enum if_type if_type, int devnum, int hwpart);
>  
> +/**
> + * blk_get_from_parent() - obtain a block device by looking up its parent
> + *
> + * All devices with
> + */
> +int blk_get_from_parent(struct udevice *parent, struct udevice **devp);

Don't need to consider whether CONFIG_BLK is defined or not?
blk_get_from_parent() is declared in blk-uclass.c

Best Regards,
Jaehoon Chung

> +
>  #endif
> diff --git a/test/dm/blk.c b/test/dm/blk.c
> index 5c5eb829a0..923e8d95f0 100644
> --- a/test/dm/blk.c
> +++ b/test/dm/blk.c
> @@ -150,3 +150,21 @@ static int dm_test_blk_devnum(struct unit_test_state *uts)
>  	return 0;
>  }
>  DM_TEST(dm_test_blk_devnum, DM_TESTF_SCAN_PDATA | DM_TESTF_SCAN_FDT);
> +
> +/* Test that we can get a block from its parent */
> +static int dm_test_blk_get_from_parent(struct unit_test_state *uts)
> +{
> +	struct udevice *dev, *blk;
> +
> +	ut_assertok(uclass_get_device(UCLASS_MMC, 0, &dev));
> +	ut_assertok(blk_get_from_parent(dev, &blk));
> +
> +	ut_assertok(uclass_get_device(UCLASS_I2C, 0, &dev));
> +	ut_asserteq(-ENOTBLK, blk_get_from_parent(dev, &blk));
> +
> +	ut_assertok(uclass_get_device(UCLASS_GPIO, 0, &dev));
> +	ut_asserteq(-ENODEV, blk_get_from_parent(dev, &blk));
> +
> +	return 0;
> +}
> +DM_TEST(dm_test_blk_get_from_parent, DM_TESTF_SCAN_PDATA | DM_TESTF_SCAN_FDT);
>