Hello, This patch series is a new approach at implementing some functionality I previously attempted as a separate driver in drivers/misc [0], but I think (as suggested by Greg in that thread) ultimately makes more sense being built into the regulator subsystem. The hardware arrangement essentially amounts to a regulator whose output doesn't supply any devices within the system, but instead simply feeds a "dumb" external output -- picture a typical power distribution unit (PDU), but with DC outputs instead of AC. (The specific system I'm targeting at the moment is the Delta AHE-50DC Open19 power shelf [1], for which I'm working on a port of OpenBMC.) Supporting this doesn't require much in the way of new functionality, just some plumbing so that userspace (typically a human operator manually switching outlets on and off) can access the necessary bits of the regulator subsystem, and some DT bindings to describe this sort of setup. The DT bindings changes (patches 1 and 2) consist of a boolean regulator property to mark it as supplying an external output, and a reg-external-output binding to act as a downstream device representing that output. The redundancy between the two maybe isn't entirely ideal, but it was the cleanest approach I've been able to come up with so far in terms of working with the regulator subsystem; I'm certainly open to suggestions for better ways of going about this. Within the regulator core, patch 3 exposes the REGULATOR_ERROR_* flags (for regulators that define a get_error_flags() operation) to userspace as a set of read-only sysfs attributes, so that operators can diagnose the cause of faults that may occur, such as current or thermal limits being exceeded. Patch 4 adds support for the regulator-external-output property with a couple of small functional tweaks, making the 'state' sysfs attribute writable and skipping the auto-disabling in regulator_late_cleanup(). Patch 5 adds a special-purpose regulator_get_type (EXTERNAL_GET), and patch 6 adds a tiny driver acting as a placeholder for an external output, using EXTERNAL_GET. Review/feedback appreciated! Thanks, Zev [0] https://lore.kernel.org/openbmc/20220308011811.10353-1-zev@xxxxxxxxxxxxxxxxx/ [1] https://www.open19.org/marketplace/delta-16kw-power-shelf/ Zev Weiss (6): dt-bindings: regulator: Add regulator-external-output property dt-bindings: regulator: Add reg-external-output regulator: core: Add error flags to sysfs attributes regulator: core: Add external-output support regulator: core: Add external get type regulator: core: Add external-consumer driver .../ABI/testing/sysfs-class-regulator | 85 ++++++++++++ .../regulator/reg-external-output.yaml | 37 +++++ .../bindings/regulator/regulator.yaml | 6 + drivers/regulator/Kconfig | 9 ++ drivers/regulator/core.c | 130 ++++++++++++++++-- drivers/regulator/devres.c | 7 + drivers/regulator/internal.h | 3 + drivers/regulator/of_regulator.c | 2 + include/linux/regulator/machine.h | 1 + 9 files changed, 272 insertions(+), 8 deletions(-) create mode 100644 Documentation/devicetree/bindings/regulator/reg-external-output.yaml -- 2.36.0
