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authorSimon Glass <sjg@chromium.org>2014-07-23 06:55:20 -0600
committerSimon Glass <sjg@chromium.org>2014-07-23 14:08:37 +0100
commite59f458de6999b8a786da857e653db6777f675ca (patch)
tree0e57f9b83b6a484fce0543562c7c313e66b89c75 /doc/driver-model/README.txt
parent997c87bb0b1981fd33e34cefc26d9138f27326ce (diff)
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dm: Introduce per-child data for devices
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>
Diffstat (limited to 'doc/driver-model/README.txt')
-rw-r--r--doc/driver-model/README.txt25
1 files changed, 17 insertions, 8 deletions
diff --git a/doc/driver-model/README.txt b/doc/driver-model/README.txt
index 59ef05c..11af35d 100644
--- a/doc/driver-model/README.txt
+++ b/doc/driver-model/README.txt
@@ -95,7 +95,7 @@ are provided in test/dm. To run them, try:
You should see something like this:
<...U-Boot banner...>
- Running 19 driver model tests
+ Running 20 driver model tests
Test: dm_test_autobind
Test: dm_test_autoprobe
Test: dm_test_bus_children
@@ -103,6 +103,7 @@ You should see something like this:
Device 'c-test@0': seq 0 is in use by 'a-test'
Device 'c-test@1': seq 1 is in use by 'd-test'
Test: dm_test_bus_children_funcs
+ Test: dm_test_bus_parent_data
Test: dm_test_children
Test: dm_test_fdt
Device 'd-test': seq 3 is in use by 'b-test'
@@ -489,16 +490,23 @@ steps (see device_probe()):
stored in the device, but it is uclass data. owned by the uclass driver.
It is possible for the device to access it.
- d. All parent devices are probed. It is not possible to activate a device
+ d. If the device's immediate parent specifies a per_child_auto_alloc_size
+ then this space is allocated. This is intended for use by the parent
+ device to keep track of things related to the child. 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.
+
+ e. All parent devices are probed. It is not possible to activate a device
unless its predecessors (all the way up to the root device) are activated.
This means (for example) that an I2C driver will require that its bus
be activated.
- e. The device's sequence number is assigned, either the requested one
+ f. The device's sequence number is assigned, either the requested one
(assuming no conflicts) or the next available one if there is a conflict
or nothing particular is requested.
- f. If the driver provides an ofdata_to_platdata() method, then this is
+ g. If the driver provides an ofdata_to_platdata() method, then this is
called to convert the device tree data into platform data. This should
do various calls like fdtdec_get_int(gd->fdt_blob, dev->of_offset, ...)
to access the node and store the resulting information into dev->platdata.
@@ -514,7 +522,7 @@ steps (see device_probe()):
data, one day it is possible that U-Boot will cache platformat data for
devices which are regularly de/activated).
- g. The device's probe() method is called. This should do anything that
+ h. The device's probe() method is called. This should do anything that
is required by the device to get it going. This could include checking
that the hardware is actually present, setting up clocks for the
hardware and setting up hardware registers to initial values. The code
@@ -529,9 +537,9 @@ steps (see device_probe()):
allocate the priv space here yourself. The same applies also to
platdata_auto_alloc_size. Remember to free them in the remove() method.
- h. The device is marked 'activated'
+ i. The device is marked 'activated'
- i. The uclass's post_probe() method is called, if one exists. This may
+ j. The uclass's post_probe() method is called, if one exists. This may
cause the uclass to do some housekeeping to record the device as
activated and 'known' by the uclass.
@@ -562,7 +570,8 @@ remove it. This performs the probe steps in reverse:
to be sure that no hardware is running, it should be enough to remove
all devices.
- d. The device memory is freed (platform data, private data, uclass data).
+ d. The device memory is freed (platform data, private data, uclass data,
+ parent data).
Note: Because the platform data for a U_BOOT_DEVICE() is defined with a
static pointer, it is not de-allocated during the remove() method. For