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Document the sysfs and debugfs interfaces of the Kandou KB9002 hwmon driver. Signed-off-by: Andy Chung <Andy.Chung@amd.com> Link: https://lore.kernel.org/r/20260724-kb9002-upstream-v5-4-9523c3ffe83a@amd.com Signed-off-by: Guenter Roeck <linux@roeck-us.net>
65 lines
2.1 KiB
ReStructuredText
65 lines
2.1 KiB
ReStructuredText
.. SPDX-License-Identifier: GPL-2.0-or-later
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Kernel driver kb9002
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====================
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Supported chips:
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* Kandou KB9002
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Prefix: 'kb9002'
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Addresses scanned: -
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Datasheet: KA-015171-PD (available from Kandou under NDA)
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Author: Andy Chung <andy.chung@amd.com>
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Description
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-----------
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The Kandou KB9002 is an 8-lane PCIe 5.0 retimer with an integrated
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microcontroller. It exposes an SMBus 3.0 target (with mandatory PEC)
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on its sideband interface. The internal firmware aggregates per-lane
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die temperatures and publishes the maximum value through a 16-bit
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addressed register window.
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This driver reports that aggregated maximum as the only hwmon
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temperature channel. The running firmware version and the firmware
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boot status are exposed under debugfs.
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sysfs interface
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---------------
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================== ===============================================
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temp1_input Aggregated maximum die temperature across all
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active lanes (millidegrees Celsius).
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================== ===============================================
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debugfs interface
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-----------------
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Files live in the per-client debugfs directory created by the I2C
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core: ``/sys/kernel/debug/i2c/i2c-<bus>/<bus>-<addr>/``.
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================== ===============================================
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fw_ver Running firmware version in
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"major.minor.patch.suffix" format. Read-only.
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fw_load_status Firmware boot status: "normal" once firmware has
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finished initialising, "abnormal" otherwise.
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Read-only.
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================== ===============================================
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Notes
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-----
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The driver requires ``I2C_FUNC_SMBUS_BLOCK_DATA``,
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``I2C_FUNC_SMBUS_PEC`` and ``I2C_FUNC_I2C`` from the host adapter. The
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last is needed only during probe for the host-interface mode switch;
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runtime accesses use SMBus block transactions exclusively.
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The retimer's SMBus address is configurable on three strap pins and
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ranges from 0x20 to 0x27. The address is selected through device tree
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(or i2c board info) the same way as any other I2C device; the driver
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does not auto-detect.
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