On 25 July 2015 at 06:52, Masahiro Yamada yamada.masahiro@socionext.com wrote:
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
Changes in v4:
- Comment struct devres
Changes in v3:
- Update git-description. Do not mention about the DM core part.
Changes in v2:
- Add more APIs: _free, _find, _get, _remove, _destroy, _release
- Move devres_release_probe() and devres_release_all() decrlarations to dm/device-internal.h
- Move comments to headers
drivers/core/Kconfig | 10 +++ drivers/core/Makefile | 2 +- drivers/core/device-remove.c | 5 ++ drivers/core/device.c | 3 + drivers/core/devres.c | 196 +++++++++++++++++++++++++++++++++++++++++++ include/dm/device-internal.h | 19 +++++ include/dm/device.h | 140 +++++++++++++++++++++++++++++++ 7 files changed, 374 insertions(+), 1 deletion(-)
Acked-by: Simon Glass sjg@chromium.org