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hwmon: add driver for ltc4284 - #3450

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actorreno wants to merge 62 commits into
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staging/ltc4284
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hwmon: add driver for ltc4284#3450
actorreno wants to merge 62 commits into
mirror_ci/groeck/linux-staging/hwmon-nextfrom
staging/ltc4284

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@actorreno

@actorreno actorreno commented Jul 21, 2026 •
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PR Description

The LTC4284 is a high-power hot swap controller designed for -48V distributed power systems supporting up to 2500W applications. It features dual-gate MOSFET drivers with multiple operation modes, comprehensive monitoring capabilities, and advanced protection.

Datasheet: LTC4284

This PR is for upstreaming
This is for dev branch in case some tests/features are requested: #3351
This supersedes the old draft PR #3126

Key features:

  • Dual current sensing with independent sense resistors
  • Voltage, current, power, and energy monitoring
  • Four operation modes: single, parallel, staged start (high/low stress)
  • Programmable current limiting (15mV-30mV sense voltage range)
  • Min/max history tracking with reset capability
  • Comprehensive fault detection and logging
  • I2C interface with regmap support

PR Type

  • Bug fix (a change that fixes an issue)
  • New feature (a change that adds new functionality)
  • Breaking change (a change that affects other repos or cause CIs to fail)

PR Checklist

  • I have conducted a self-review of my own code changes
  • I have compiled my changes, including the documentation
  • I have tested the changes on the relevant hardware
  • I have updated the documentation outside this repo accordingly
  • I have provided links for the relevant upstream lore

@gastmaier
gastmaier force-pushed the mirror_ci/groeck/linux-staging/hwmon-next branch from 8411d1b to a17a53a Compare July 22, 2026 00:00
@actorreno
actorreno marked this pull request as ready for review July 22, 2026 03:41
@actorreno
actorreno requested a review from nunojsa July 22, 2026 03:42
@nunojsa

nunojsa commented Jul 28, 2026

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The ltc4283 driver is already upstream! Any reason this device cannot be supported in that driver?

@actorreno

actorreno commented Jul 29, 2026

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I was pulled late into the project (around May), so I simply continued work until I ended up being the submitter.
(LTC4283 got upstreamed around June it seems)

I wasn't aware of ltc4283 being in the works, and I think we can't easily add on ltc4282.

Digging some history there's this #3126 that seemed to have decided why we have a separate driver code.

but now that I see LTC4283 I am inclined to just add support on it, the code overlap seems considerable compared to probable extra code lines.

@actorreno
actorreno force-pushed the staging/ltc4284 branch 9 times, most recently from b275459 to 5e45c36 Compare July 29, 2026 22:49
@actorreno

actorreno commented Jul 29, 2026

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v2:

  • now adding support on top of ltc4283.c rather than its separate driver

For the gpio support, I was thinking since it's exactly the same feature, just mentioning it in kconfig was enough

@gastmaier
gastmaier force-pushed the mirror_ci/groeck/linux-staging/hwmon-next branch 8 times, most recently from ec684c3 to 16e3a40 Compare August 29, 2026 00:00
@gastmaier
gastmaier force-pushed the mirror_ci/groeck/linux-staging/hwmon-next branch 5 times, most recently from c70491f to 666afcf Compare September 3, 2026 00:00
Sanman Pradhan and others added 4 commits September 16, 2026 17:06
Sanman Pradhan @groeck
dt-bindings: trivial-devices: Add TI TPS536C7
7bc4029 
TPS536C7 is a PMBus-compliant dual-channel D-CAP+ multiphase step-down
controller. Add its compatible string.

Signed-off-by: Sanman Pradhan <psanman@juniper.net>
Acked-by: Conor Dooley <conor.dooley@microchip.com>
Link: https://patch.msgid.link/20260915164823.160977-3-sanman.pradhan@hpe.com
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Sanman Pradhan @groeck
hwmon: (pmbus/tps53679) Add support for TPS536C7
b438459 
TPS536C7 is a dual-channel D-CAP+ step-down controller whose channels are
distributed across a configurable number of phases (N+M, up to 12 total).
Whether channel B (PMBus page 1) exists depends on the phase configuration
register, so the page count is derived at probe time.

Factor the TPS53676 phase-map parsing into a shared helper and reuse it
for TPS536C7. Only aggregate per-channel telemetry is exposed: leave
info->phases[] unset so the PMBus core never programs the PHASE selector
on every read (and because TPS536C7 can place up to 12 phases on channel
A, exceeding PMBUS_PHASES). Report VOUT in linear format like TPS53676.

Since the core never programs PHASE, set it to 0xff on each populated
page so READ_IOUT reports the aggregate channel current, and verify it
(PHASE can be write-protected). Fail identification if aggregate
selection cannot be established, since otherwise a single phase current
could be reported as the channel total.

A configuration with no channel-A phase is rejected with -EOPNOTSUPP:
the PMBus core models pages as the contiguous range 0..pages-1 and
cannot represent a channel-A-absent topology.

On the tested TPS536C7 (device ID 54 49 53 6c 70 00, CAPABILITY 0xd0),
block reads of IC_DEVICE_ID and USER_DATA_03 return -EBADMSG with PEC
enabled, while retrying those two reads without PEC returns the expected
6- and 24-byte payloads. Standard byte/word telemetry keeps using PEC,
so only those two identification reads fall back to no-PEC.

Co-developed-by: Senthil Muniyappan <smuniyappan@juniper.net>
Co-developed-by: Vaibhav Agarwal <avaibhav@juniper.net>
Signed-off-by: Sanman Pradhan <psanman@juniper.net>
Link: https://patch.msgid.link/20260915164823.160977-4-sanman.pradhan@hpe.com
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
@pzalewski-thegoodpenguin @groeck
hwmon: use named initializers for acpi_device_id
db2e88c 
Use a designated initializer for the acpi_device_id fields which makes the
code more readable and consistent with how lists are initialized in the
rest of the kernel code base. Also drop explicitly setting fields to 0
where it is redundant.

Unify the list terminator to have a single space between the brackets and
no trailing comma.

Signed-off-by: Pawel Zalewski <pzalewski@thegoodpenguin.co.uk>
Link: https://patch.msgid.link/20260915-acpi-hwmon-v2-1-39d17c748eb6@thegoodpenguin.co.uk
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Sanman Pradhan @groeck
hwmon: (pmbus/tps53679) Select page 0 for single-page TPS536C7
29e2ca9 
tps536c7_identify() sets info->pages to 1 for a single-channel part and
then accesses page 0 (writing PMBUS_PHASE) without ensuring PAGE is
actually 0. pmbus_set_page() does not update the PAGE register when
info->pages is 1, so if boot firmware left PAGE set to another value the
PHASE writes and subsequent telemetry may target the wrong page.

Select page 0 explicitly before configuring PHASE.

Signed-off-by: Sanman Pradhan <psanman@juniper.net>
Link: https://patch.msgid.link/20260916235406.681131-3-sanman.pradhan@hpe.com
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
@cseci
deploy: 7081695
8ea9c84 
patch ci

Signed-off-by: CSE CI <cse-ci-notifications@analog.com>
@gastmaier
gastmaier force-pushed the mirror_ci/groeck/linux-staging/hwmon-next branch from 98ace74 to 8ea9c84 Compare September 18, 2026 00:01
@actorreno
actorreno changed the base branch from mirror_ci/groeck/linux-staging/hwmon-next to main September 18, 2026 00:51
@actorreno
actorreno changed the base branch from main to mirror_ci/groeck/linux-staging/hwmon-next September 18, 2026 00:51
@actorreno
dt-bindings: hwmon: ltc4283: add ltc4284
025541a 
The LTC4283 is a negative voltage hot swap controller that drives an
external N-channel MOSFET to allow a board to be safely inserted and
removed from a live backplane.

Note that this device has a MODE pin that is determined by differing
voltage levels (VEE, VIN, INTVCC, or left open) and cannot be
controlled via software or GPIO.

Signed-off-by: Alexis Czezar Torreno <alexisczezar.torreno@analog.com>
@actorreno
hwmon: ltc4283: Add support for the LTC4284 swap controller
7793a5d 
Support the LTC4284 Hot Swap Controller. It is very Similar to LTC4283 but for
higher power. The device features programmable current limit with foldback and
independently adjustable inrush current to optimize the MOSFET safe operating
area (SOA). The SOA timer limits MOSFET temperature rise for reliable
protection against overstresses.

An I2C interface and onboard ADC allow monitoring of board current,
voltage, power, energy, and fault status.

Signed-off-by: Alexis Czezar Torreno <alexisczezar.torreno@analog.com>
@actorreno
gpio: gpio-ltc4283: Add support for the LTC4284 Swap Controller
6deff73 
Similar to LTC4283, LTC4284 has up to 8 pins that can be configured
as GPIOs and behaves the same.

Signed-off-by: Alexis Czezar Torreno <alexisczezar.torreno@analog.com>
@actorreno

actorreno commented Sep 18, 2026

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PR got stale, just following up on review @nunojsa
Also cleaned the commits.
Thanks!

@gastmaier
gastmaier force-pushed the mirror_ci/groeck/linux-staging/hwmon-next branch 4 times, most recently from 6afd18e to 5b34f0f Compare September 22, 2026 00:02
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