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dm: blk: Add a way to obtain a block device from its parent

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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@chromium.org>
Reviewed-by: Tom Rini <trini@konsulko.com>
This commit is contained in:
Simon Glass
2017-05-27 11:37:17 -06:00
committed by Jaehoon Chung
parent fc69d47262
commit 9f103b9cb5
3 changed files with 51 additions and 0 deletions
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26
drivers/block/blk-uclass.c
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@@ -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;