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78a3e36eec
Extend the raspberrypi-hwmon driver to expose firmware-provided voltage measurements through the hwmon subsystem. The driver now exports the following voltage inputs: - in0_input (core) - in1_input (sdram_c) - in2_input (sdram_i) - in3_input (sdram_p) Voltage values returned by firmware are converted from microvolts to millivolts as expected by the hwmon subsystem. Update the documentation related to it. The existing undervoltage sticky alarm handling is preserved and associated with the first voltage channel. Tested in - - Raspberry Pi 3b+ (Linux raspberrypi 6.12.75+rpt-rpi-v8 #1 SMP PREEMPT Debian 1:6.12.75-1+rpt1 (2026-03-11) aarch64 GNU/Linux) Signed-off-by: Shubham Chakraborty <chakrabortyshubham66@gmail.com> Reviewed-by: Florian Fainelli <florian.fainelli@broadcom.com> Link: https://lore.kernel.org/r/20260517080445.103962-3-chakrabortyshubham66@gmail.com [groeck: Added missing empty line after declaration] Signed-off-by: Guenter Roeck <linux@roeck-us.net>
37 lines
1.0 KiB
ReStructuredText
37 lines
1.0 KiB
ReStructuredText
Kernel driver raspberrypi-hwmon
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===============================
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Supported boards:
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* Raspberry Pi A+ (via GPIO on SoC)
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* Raspberry Pi B+ (via GPIO on SoC)
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* Raspberry Pi 2 B (via GPIO on SoC)
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* Raspberry Pi 3 B (via GPIO on port expander)
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* Raspberry Pi 3 B+ (via PMIC)
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Author: Stefan Wahren <stefan.wahren@i2se.com>
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Description
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-----------
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This driver periodically polls a mailbox property of the VC4 firmware to detect
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undervoltage conditions.
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Sysfs entries
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-------------
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======================= ======================================================
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in0_input Core voltage in millivolts
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in1_input SDRAM controller voltage in millivolts
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in2_input SDRAM I/O voltage in millivolts
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in3_input SDRAM PHY voltage in millivolts
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in0_label "core"
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in1_label "sdram_c"
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in2_label "sdram_i"
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in3_label "sdram_p"
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in0_lcrit_alarm Undervoltage alarm
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======================= ======================================================
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The voltage inputs and labels are only exposed if the firmware reports support
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for the corresponding voltage ID.
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