Some devices (particularly bus devices) must track their children, knowing
when a new child is added so that it can be set up for communication on the
bus.
Add a child_pre_probe() method to provide this feature, and a corresponding
child_post_remove() method.
Signed-off-by: Simon Glass <sjg@chromium.org>
Some device types can have child devices and want to store information
about them. For example a USB flash stick attached to a USB host
controller would likely use this space. The controller can hold
information about the USB state of each of its children.
The data is stored attached to the child device in the 'parent_priv'
member. It can be auto-allocated by dm when the child is probed. To
do this, add a per_child_auto_alloc_size value to the parent driver.
Signed-off-by: Simon Glass <sjg@chromium.org>
Devices can have childen that can be addressed by a simple index, the
sequence number or a device tree offset. Add functions to access a child
in each of these ways.
The index is typically used as a fallback when the sequence number is not
available. For example we may use a serial UART with sequence number 0 as
the console, but if no UART has sequence number 0, then we can fall back
to just using the first UART (index 0).
The device tree offset function is useful for buses, where they want to
locate one of their children. The device tree can be scanned to find the
offset of each child, and that offset can then find the device.
Signed-off-by: Simon Glass <sjg@chromium.org>
At present only root nodes in the device tree are scanned for devices.
But some devices can have children. For example a SPI bus may have
several children for each of its chip selects.
Add a function which scans subnodes and binds devices for each one. This
can be used for the root node scan also, so change it.
A device can call this function in its bind() or probe() methods to bind
its children.
Signed-off-by: Simon Glass <sjg@chromium.org>
Simon Glass