1.. SPDX-License-Identifier: GPL-2.0-or-later 2 3Kernel driver kb9002 4==================== 5 6Supported chips: 7 8 * Kandou KB9002 9 10 Prefix: 'kb9002' 11 12 Addresses scanned: - 13 14 Datasheet: KA-015171-PD (available from Kandou under NDA) 15 16Author: Andy Chung <andy.chung@amd.com> 17 18Description 19----------- 20 21The Kandou KB9002 is an 8-lane PCIe 5.0 retimer with an integrated 22microcontroller. It exposes an SMBus 3.0 target (with mandatory PEC) 23on its sideband interface. The internal firmware aggregates per-lane 24die temperatures and publishes the maximum value through a 16-bit 25addressed register window. 26 27This driver reports that aggregated maximum as the only hwmon 28temperature channel. The running firmware version and the firmware 29boot status are exposed under debugfs. 30 31sysfs interface 32--------------- 33 34================== =============================================== 35temp1_input Aggregated maximum die temperature across all 36 active lanes (millidegrees Celsius). 37================== =============================================== 38 39debugfs interface 40----------------- 41 42Files live in the per-client debugfs directory created by the I2C 43core: ``/sys/kernel/debug/i2c/i2c-<bus>/<bus>-<addr>/``. 44 45================== =============================================== 46fw_ver Running firmware version in 47 "major.minor.patch.suffix" format. Read-only. 48fw_load_status Firmware boot status: "normal" once firmware has 49 finished initialising, "abnormal" otherwise. 50 Read-only. 51================== =============================================== 52 53Notes 54----- 55 56The driver requires ``I2C_FUNC_SMBUS_BLOCK_DATA``, 57``I2C_FUNC_SMBUS_PEC`` and ``I2C_FUNC_I2C`` from the host adapter. The 58last is needed only during probe for the host-interface mode switch; 59runtime accesses use SMBus block transactions exclusively. 60 61The retimer's SMBus address is configurable on three strap pins and 62ranges from 0x20 to 0x27. The address is selected through device tree 63(or i2c board info) the same way as any other I2C device; the driver 64does not auto-detect. 65