U-Boot with I2C_DM enabled is not capable to list i2c busses connected to i2c mux. For getting this work there is a need to find out highest alias ID and use this uniq number for new buses connected to I2C mux. This series is making this happen.
There is only one missing piece which is that also i2c controllers which are not listed in DT are not using this feature. For getting this work it would be necessary to setup dev->req_seq in pre_bind function.
int i2c_pre_bind(struct udevice *dev) { if (dev->req_seq == -1) { dev->req_seq = ++i2c_highest_id; } return 0; }
It can be done also in post_bind but it looks quite weird that controller has highest ID then i2c-mux sub-buses connected to it. For example: ZynqMP> i2c bus Bus 3: i2c@ff020000 20: gpio@20, offset len 1, flags 0 21: gpio@21, offset len 1, flags 0 75: i2c-mux@75, offset len 1, flags 0 Bus 0: i2c@ff020000->i2c-mux@75->i2c@0 Bus 1: i2c@ff020000->i2c-mux@75->i2c@1 Bus 2: i2c@ff020000->i2c-mux@75->i2c@2 Bus 17: i2c@ff030000 74: i2c-mux@74, offset len 1, flags 0 75: i2c-mux@75, offset len 1, flags 0 Bus 4: i2c@ff030000->i2c-mux@74->i2c@0 Bus 5: i2c@ff030000->i2c-mux@74->i2c@1 Bus 6: i2c@ff030000->i2c-mux@74->i2c@2 Bus 7: i2c@ff030000->i2c-mux@74->i2c@3 ...
That's why I think it would be better to introduce pre_bind hooks and call it in device_bind_common() before binding childs.
Thanks, Michal
Michal Simek (4): dm: core: Add of_alias_get_highest_id() fdt: Introduce fdtdec_get_alias_highest_id() i2c: dm: Record maximum id of devices before probing devices i2c: mux: Add support for not listed sub-buses
drivers/core/of_access.c | 18 ++++++++++++++++++ drivers/i2c/i2c-uclass.c | 19 +++++++++++++++++++ drivers/i2c/muxes/i2c-mux-uclass.c | 35 +++++++++++++++++++++++++++++++++-- include/dm/of_access.h | 9 +++++++++ include/fdtdec.h | 13 +++++++++++++ include/i2c.h | 3 +++ lib/fdtdec.c | 33 +++++++++++++++++++++++++++++++++ 7 files changed, 128 insertions(+), 2 deletions(-)