+U-Boot

Hi Tim,

On 10 April 2015 at 10:46, Tim Harvey tharvey@gateworks.com wrote:

On Fri, Apr 10, 2015 at 9:39 AM, Simon Glass sjg@chromium.org wrote:

...

I've wanted this feature for some years, and also the ability to define the environment offset/address/size (and other parameters) dynamically.

This feels like a job for driver model. We could have an environment uclass with operations like load and save. Then mmc and nand could implement drivers for this uclass.

Probably better that than a linker_list.

Simon,

If its not too much of a time-sink I would love to take a stab at it.

I've been too swamped to even follow all your work regarding DM. Could you point me to any existing docs/presentation/simple-example/similar-patches that will give me an idea of what needs to be done? Even spit-balling some psuedo-code would get me started.

Sure. There's a doc/driver-model/README.

Here are my ideas:

1. Add a new value to the enum in uclass-id.h

2. Create a env-uclass.c file (see demo-uclass.c and dm-demo.h for an example). Add the operations you want to support. Enable it if CONFIG_DM_ENV is defined (you can add this new option to Kconfig).

3. Add a sandbox environment driver which implements your operations - add a U_BOOT_DRIVER() for your driver, setting .ops to contain functions that implement the uclass operations for sandbox. Then and some tests (test/dm/env.c). Then it should be possible to use saveenv(), etc. from sandbox. The implementation could store it in a file, perhaps (e.g. using os_open(), etc.). This should speed up development too since you don't need to test on real hardware.

4. Implement env_relocate() etc. in the uclass file, so that if CONFIG_DM_ENV is defined you can't define the other ones - CONFIG_ENV_IS_IN_... or you will get duplicate functions.

5. In your env_relocate(), you can do something like uclass_get_device(UCLASS_ENV, 0, &dev) to get the default environment device. Then call the correct operation.

6. Add more driver support - e.g. in env_mmc.c, add a U_BOOT_DRIVER() for your mmc driver, setting .ops to contain functions that implement the uclass operations for mmc.

That should be most of it. I don't think it's too tricky. It would be a big win. I'm happy to help with review and advice. Plus I'll sign up to do SPI once you are done.

Regards, Simon