Hello, This is a second revision of the v1 patch series posted previously [2]. Changes since v1: - dropped pmbus/lm25066 patches, submitted separately via hwmon tree [Guenter] - fixed indentation in power-efuse.yaml [Rob's bot] - added more detailed description in power-efuse.yaml [Rob] - added sysfs ABI documentation [Greg] - replaced manual struct attribute_group and sysfs_create_group() with ATTRIBUTE_GROUPS() and driver.dev_groups [Greg] A lightly edited version of the previous cover letter follows. This patch series is another incarnation of some previous efforts [0] at enabling userspace access to the OPERATION state (and now status flags) of PMBus devices, specifically with respect to efuses protecting general-purpose power outputs. This functionality is an important component enabling a port of OpenBMC to the Delta AHE-50DC Open19 power shelf [1]. The first patch adds dt-bindings, and the second adds the implementation of the power-efuse driver. The driver is fairly simple; it merely provides a sysfs interface to enable, disable, and retrieve error flags from an underlying regulator (which in the expected usage will most likely be a PMBus device). There is one aspect of its usage of the regulator API I'm a bit uncertain about, however: this driver seems like a case where an exclusive 'get' of the regulator (i.e. devm_regulator_get_exclusive() instead of devm_regulator_get() in efuse_probe()) would be appropriate, since in the intended usage no other device should be using an efuse's regulator. With an exclusive get though, the regulator's use_count and the consumer's enable_count don't balance out properly to allow the enable/disable operations to work properly (the former ending up one more than the latter, leading to enable_count underflows on attempts to disable the regulator). So at least for now it's using a non-exclusive get -- I'd be happy to hear any pointers on a way to allow an exclusive get to work here, though. Thanks, Zev [0] https://lore.kernel.org/openbmc/YGLepYLvtlO6Ikzs@xxxxxxxxxxxxxxxxxxxxxxxx/ [1] https://www.open19.org/marketplace/delta-16kw-power-shelf/ [2] https://lore.kernel.org/openbmc/20220217104444.7695-1-zev@xxxxxxxxxxxxxxxxx/ Zev Weiss (2): dt-bindings: Add power-efuse binding misc: Add power-efuse driver .../ABI/testing/sysfs-driver-power-efuse | 32 +++ .../devicetree/bindings/misc/power-efuse.yaml | 49 ++++ MAINTAINERS | 5 + drivers/misc/Kconfig | 15 ++ drivers/misc/Makefile | 1 + drivers/misc/power-efuse.c | 212 ++++++++++++++++++ 6 files changed, 314 insertions(+) create mode 100644 Documentation/ABI/testing/sysfs-driver-power-efuse create mode 100644 Documentation/devicetree/bindings/misc/power-efuse.yaml create mode 100644 drivers/misc/power-efuse.c -- 2.35.1
