Sandbox i2c works using emulation drivers which are currently children of the i2c device:
rtc_0: rtc@43 { reg = <0x43>; compatible = "sandbox-rtc"; emul { compatible = "sandbox,i2c-rtc"; }; };
In this case the emulation device is attached to i2c bus on address 0x43 and provides the Real-Time-Clock (RTC) functionality.
However this is not ideal, since every device on an I2C bus has a child device. This is only really the case for sandbox, but we want to avoid special-case code for sandbox.
A better approach seems to be to add a separate node on the bus, an 'emulation parent'. This can be given a bogus address (such as 0xff) and hides all the emulators away. Then we can use a phandle to point from the device to the correct emualtor, and only on sandbox. The code to find an emulator does not interfere with normal i2c operation.
Add a new UCLASS_I2C_EMUL_PARENT uclass which allows finding an emulator given a bus, and finding a bus given an emulator. This will be used in a follow-on patch.
Signed-off-by: Simon Glass sjg@chromium.org ---
Changes in v2: None
drivers/i2c/i2c-emul-uclass.c | 77 +++++++++++++++++++++++++++++++++++ include/dm/uclass-id.h | 1 + include/i2c.h | 21 ++++++++++ 3 files changed, 99 insertions(+)
Applied to u-boot-dm/master, thanks!