Hello all See previous series for some background context [1] Some x86 laptops with ACPI tables designed for Windows have a TPS68470 PMIC providing regulators and clocks to camera modules. The DSDT tables for those cameras lack any power control methods, declaring only a dependency on the ACPI device representing the TPS68470. This leaves the regulator framework with no means of determining appropriate voltages for the regulators provided by the PMIC, or of determining which regulators relate to which of the sensor's requested supplies. This series is a prototype of an emulation of the device tree regulator initialisation and lookup functions, using software nodes. Software nodes relating to each regulator are registered as children of the TPS68470's ACPI firmware node. Those regulators have properties describing their constraints (for example "regulator-min-microvolt"). Similarly, software nodes are registered and assigned as secondary to the Camera's firmware node - these software nodes have reference properties named after the supply in the same way as device tree's phandles, for example "avdd-supply", and linking to the software node assigned to the appropriate regulator. We can then use those constraints to specify the appropriate voltages and the references to allow the camera drivers to look up the correct regulator device. Although not included in this series, I would plan to use a similar method for linking the clocks provided by the TPS68470 to the sensor so that it can be discovered too. I'm posting this to see if people agree it's a good approach for tackling the problem; I may be overthinking this and there's a much easier way that I should be looking at instead. It will have knock-ons in the cio2-bridge code [2], as that is adding software nodes to the same sensors to connect them to the media graph. Similarly, is the board file an acceptable solution, or should we just define the configuration for these devices (there's three orf our laptop models in scope) in int3472-tps68470 instead? Thanks Dan [1] https://lore.kernel.org/lkml/20210603224007.120560-1-djrscally@xxxxxxxxx/ [2] https://elixir.bootlin.com/linux/latest/source/drivers/media/pci/intel/ipu3/cio2-bridge.c#L166 Daniel Scally (2): regulator: Add support for software node connections platform/surface: Add Surface Go 2 board file MAINTAINERS | 6 + drivers/platform/surface/Kconfig | 10 ++ drivers/platform/surface/Makefile | 1 + drivers/platform/surface/surface_go_2.c | 135 +++++++++++++++++++++ drivers/regulator/Kconfig | 6 + drivers/regulator/Makefile | 1 + drivers/regulator/core.c | 23 ++++ drivers/regulator/swnode_regulator.c | 111 +++++++++++++++++ include/linux/regulator/swnode_regulator.h | 33 +++++ 9 files changed, 326 insertions(+) create mode 100644 drivers/platform/surface/surface_go_2.c create mode 100644 drivers/regulator/swnode_regulator.c create mode 100644 include/linux/regulator/swnode_regulator.h -- 2.25.1
