Vincent JardinandPeng Fan
cfb4272552
Add U-Boot's PMBus 1.x layer: the decoder/transport library, the
pmbus CLI command and a generic DT binding.
The subsequent commits provide the UCLASS_REGULATOR adapter and per-chip
drivers.
U-Boot's PMBus support is not a hwmon clone of Linux's
drivers/hwmon/pmbus/. Linux owns the runtime side (polling, sysfs,
alert IRQs, fan loops). U-Boot owns the boot-time side in order to,
- identify the PMBus regulators a board carries: MFR_ID/
MFR_MODEL/MFR_REVISION + sanity checks.
- print telemetry (VIN/VOUT/IIN/IOUT/POUT/TEMP) so an
operator can confirm rail voltages and faults before the kernel
- decode any chip alerts (STATUS_VOUT/STATUS_IOUT/STATUS_INPUT/
STATUS_TEMPERATURE/STATUS_CML) so a boot log shows why the
previous boot failed or the board had been power cycled because
of an outage (typically over temperature or under current).
Out of scope by design: no periodic polling, no sysfs, no fan-speed
control loop, no PMBUS_VIRT_* sensor virtualisation, no caching.
If a use case needs any of those, the answer should be "wait until
Linux comes up". It shall remain a thin layer.
The constants and structural shape (command codes, status bit names,
sensor-class enum, format enum, struct pmbus_driver_info) are
mirrored from Linux drivers/hwmon/pmbus/pmbus.h verbatim. The
decoders/encoders are reimplemented from the PMBus 1.3
specification because the surrounding hwmon context (struct
pmbus_data, sysfs caching, hwmon publication) does not apply.
The main benefits:
- One framework + CLI for any board carrying PMBus regulators:
no per-board PMBus implementation required anymore.
- Boards call pmbus_print_telemetry() / pmbus_print_status_word()
directly from boot init for a snapshot, sharing all decode +
format-dispatch with the CLI.
- Linux-compatible constants and DT binding so porting an existing
drivers/hwmon/pmbus/ chip is mechanical.
- Boot-time AVS/VID rail trim reuses the same decoders and
encoders as the CLI and the regulator path: no duplicate math.
Signed-off-by: Vincent Jardin <vjardin@free.fr>
Signed-off-by: Peng Fan <peng.fan@nxp.com>
116 lines
1.2 KiB
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116 lines
1.2 KiB
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.. SPDX-License-Identifier: GPL-2.0+
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Develop U-Boot
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==============
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General
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-------
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.. toctree::
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:maxdepth: 1
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bitbangmii
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board_best_practices
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codingstyle
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designprinciples
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docstyle
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kconfig
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memory
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process
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release_cycle
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security
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sending_patches
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system_configuration
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ide_integration
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Implementation
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--------------
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.. toctree::
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:maxdepth: 1
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directories
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bloblist
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bootstd/index
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ci_testing
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commands
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config_binding
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cyclic
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devicetree/index
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distro
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driver-model/index
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environment
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init
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expo
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cedit
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event
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global_data
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lmb
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logging
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makefiles
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menus
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pmbus
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printf
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smbios
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spl
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falcon
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uefi/index
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vbe
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version
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Debugging
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---------
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.. toctree::
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:maxdepth: 1
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crash_dumps
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gdb
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trace
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Packaging
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---------
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.. toctree::
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:maxdepth: 1
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package/index
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Testing
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-------
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.. toctree::
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:maxdepth: 1
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testing
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pytest/index
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tests_writing
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tests_sandbox
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binman_tests
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Refactoring
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-----------
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.. toctree::
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:maxdepth: 1
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checkpatch
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coccinelle
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qconfig
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Code quality
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------------
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.. toctree::
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:maxdepth: 1
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python_cq
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Historical documentation
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------------------------
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.. toctree::
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:maxdepth: 2
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historical/index
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