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This new command can dump all device resources associated to
each device. The fields in every line shows:
- The address of the resource
- The size of the resource
- The name of the release function
- The stage in which the resource has been acquired (BIND/PROBE)
Currently, there is no driver using devres, but if such drivers are
implemented, the output of this command should look like this:
=> dm devres
- root_driver
- soc
- extbus
- serial@54006800
bfb541e8 (8 byte) devm_kmalloc_release BIND
bfb54440 (4 byte) devm_kmalloc_release PROBE
bfb54460 (4 byte) devm_kmalloc_release PROBE
- serial@54006900
bfb54270 (8 byte) devm_kmalloc_release BIND
- gpio@55000000
- i2c@58780000
bfb5bce8 (12 byte) devm_kmalloc_release PROBE
bfb5bd10 (4 byte) devm_kmalloc_release PROBE
- eeprom
bfb54418 (12 byte) devm_kmalloc_release BIND
Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
Acked-by: Simon Glass <sjg@chromium.org>
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In U-Boot's driver model, memory is basically allocated and freed
in the core framework. So, low level drivers generally only have
to specify the size of needed memory with .priv_auto_alloc_size,
.platdata_auto_alloc_size, etc. Nevertheless, some drivers still
need to allocate/free memory on their own in case they cannot
statically know the necessary memory size. So, I believe it is
reasonable enough to port Devres into U-boot.
Devres, which originates in Linux, manages device resources for each
device and automatically releases them on driver detach. With devres,
device resources are guaranteed to be freed whether initialization
fails half-way or the device gets detached.
The basic idea is totally the same to that of Linux, but I tweaked
it a bit so that it fits in U-Boot's driver model.
In U-Boot, drivers are activated in two steps: binding and probing.
Binding puts a driver and a device together. It is just data
manipulation on the system memory, so nothing has happened on the
hardware device at this moment. When the device is really used, it
is probed. Probing initializes the real hardware device to make it
really ready for use.
So, the resources acquired during the probing process must be freed
when the device is removed. Likewise, what has been allocated in
binding should be released when the device is unbound. The struct
devres has a member "probe" to remember when the resource was
allocated.
CONFIG_DEBUG_DEVRES is also supported for easier debugging.
If enabled, debug messages are printed each time a resource is
allocated/freed.
Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
Acked-by: Simon Glass <sjg@chromium.org>
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