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SubjectRe: [PATCH 0/5] hwmon: (nct6775) Add i2c support

On sobota 26. února 2022 14:30:42 CET Zev Weiss wrote:
> Hello,
> This patch series augments the existing nct6775 driver with support
> for the hardware's i2c interface.

Is it something I can test on my ASUS Pro WS X570-ACE board as an ordinary user, and if so, how?


> Thus far the nct6775 driver has only supported the LPC interface,
> which is the main interface by which the Super-I/O chip is typically
> connected to the host (x86) processor.
> However, these chips also provide an i2c interface, which can provide
> a way for a BMC to also monitor sensor readings from them. On some
> systems (such as the ASRock Rack ROMED8HM3 and X570-D4U) this may be
> the only way for the BMC to monitor host CPU temperatures (e.g. to
> indirectly access a TSI interface); this functionality is thus an
> important component of enabling OpenBMC to support such systems.
> In such an arrangement the Super-I/O chip is simultaneously controlled
> by two independent processors (the host and the BMC) which typically
> do not coordinate their accesses with each other. In order to avoid
> conflicts between the two, the i2c driver avoids all writes to the
> device, since the BMC's needs with the hardware are merely that it be
> able to retrieve sensor readings. This allows the host processor to
> remain ultimately in control of the chip and unaware of the BMC's use
> of it at all.
> The sole exception to the "no writes" rule for the i2c driver is for
> the bank-select register -- while I haven't been able to find any
> explicit statement in the Nuvoton datasheets guaranteeing this, all
> experiments I've done have indicated that, as one might hope, the i2c
> interface has its own bank-select register independent of the one used
> by the LPC interface.
> In terms of code structure, the approach taken in this series is to
> split the LPC-specific parts of the driver out into a separate module
> (called nct6775-platform), leaving the interface-independent parts in
> a generic driver (called nct6775-core). The nct6775-i2c driver is
> then added as an additional consumer of the nct6775-core module's
> functionality.
> The first two patches make some relatively small infrastructural
> changes to the nct6775 driver; the bulk of the core/platform driver
> split is in the third patch. The final two patches add DT bindings
> and the i2c driver itself.
> I've tested the nct6775-platform and nct6775-i2c drivers with the
> NCT6779D in an ASRock ROMED8HM3 system (the latter driver on its
> AST2500 BMC); both seem to work as expected. Broader testing would of
> course be welcome though, as is review feedback.
> Thanks,
> Zev
> Zev Weiss (5):
> hwmon: (nct6775) Rearrange attr-group initialization
> hwmon: (nct6775) Add read-only mode
> hwmon: (nct6775) Split core and platform driver
> dt-bindings: hwmon: Add nuvoton,nct6775
> hwmon: (nct6775) Add i2c driver
> .../bindings/hwmon/nuvoton,nct6775.yaml | 48 +
> drivers/hwmon/Kconfig | 32 +-
> drivers/hwmon/Makefile | 4 +-
> drivers/hwmon/{nct6775.c => nct6775-core.c} | 1464 +----------------
> drivers/hwmon/nct6775-i2c.c | 191 +++
> drivers/hwmon/nct6775-platform.c | 1185 +++++++++++++
> drivers/hwmon/nct6775.h | 233 +++
> 8 files changed, 1763 insertions(+), 1406 deletions(-)
> create mode 100644 Documentation/devicetree/bindings/hwmon/nuvoton,nct6775.yaml
> rename drivers/hwmon/{nct6775.c => nct6775-core.c} (75%)
> create mode 100644 drivers/hwmon/nct6775-i2c.c
> create mode 100644 drivers/hwmon/nct6775-platform.c
> create mode 100644 drivers/hwmon/nct6775.h

Oleksandr Natalenko (post-factum)

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