cachepc-linux

Fork of AMDESE/linux with modifications for CachePC side-channel attack
git clone https://git.sinitax.com/sinitax/cachepc-linux
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delta-ahe50dc-fan.c (3891B)

      1// SPDX-License-Identifier: GPL-2.0
      2/*
      3 * Delta AHE-50DC power shelf fan control module driver
      4 *
      5 * Copyright 2021 Zev Weiss <zev@bewilderbeest.net>
      6 */
      7
      8#include <linux/i2c.h>
      9#include <linux/kernel.h>
     10#include <linux/module.h>
     11#include <linux/pmbus.h>
     12
     13#include "pmbus.h"
     14
     15#define AHE50DC_PMBUS_READ_TEMP4 0xd0
     16
     17static int ahe50dc_fan_write_byte(struct i2c_client *client, int page, u8 value)
     18{
     19	/*
     20	 * The CLEAR_FAULTS operation seems to sometimes (unpredictably, perhaps
     21	 * 5% of the time or so) trigger a problematic phenomenon in which the
     22	 * fan speeds surge momentarily and at least some (perhaps all?) of the
     23	 * system's power outputs experience a glitch.
     24	 *
     25	 * However, according to Delta it should be OK to simply not send any
     26	 * CLEAR_FAULTS commands (the device doesn't seem to be capable of
     27	 * reporting any faults anyway), so just blackhole them unconditionally.
     28	 */
     29	return value == PMBUS_CLEAR_FAULTS ? -EOPNOTSUPP : -ENODATA;
     30}
     31
     32static int ahe50dc_fan_read_word_data(struct i2c_client *client, int page, int phase, int reg)
     33{
     34	/* temp1 in (virtual) page 1 is remapped to mfr-specific temp4 */
     35	if (page == 1) {
     36		if (reg == PMBUS_READ_TEMPERATURE_1)
     37			return i2c_smbus_read_word_data(client, AHE50DC_PMBUS_READ_TEMP4);
     38		return -EOPNOTSUPP;
     39	}
     40
     41	/*
     42	 * There's a fairly limited set of commands this device actually
     43	 * supports, so here we block attempts to read anything else (which
     44	 * return 0xffff and would cause confusion elsewhere).
     45	 */
     46	switch (reg) {
     47	case PMBUS_STATUS_WORD:
     48	case PMBUS_FAN_COMMAND_1:
     49	case PMBUS_FAN_COMMAND_2:
     50	case PMBUS_FAN_COMMAND_3:
     51	case PMBUS_FAN_COMMAND_4:
     52	case PMBUS_STATUS_FAN_12:
     53	case PMBUS_STATUS_FAN_34:
     54	case PMBUS_READ_VIN:
     55	case PMBUS_READ_TEMPERATURE_1:
     56	case PMBUS_READ_TEMPERATURE_2:
     57	case PMBUS_READ_TEMPERATURE_3:
     58	case PMBUS_READ_FAN_SPEED_1:
     59	case PMBUS_READ_FAN_SPEED_2:
     60	case PMBUS_READ_FAN_SPEED_3:
     61	case PMBUS_READ_FAN_SPEED_4:
     62		return -ENODATA;
     63	default:
     64		return -EOPNOTSUPP;
     65	}
     66}
     67
     68static struct pmbus_driver_info ahe50dc_fan_info = {
     69	.pages = 2,
     70	.format[PSC_FAN] = direct,
     71	.format[PSC_TEMPERATURE] = direct,
     72	.format[PSC_VOLTAGE_IN] = direct,
     73	.m[PSC_FAN] = 1,
     74	.b[PSC_FAN] = 0,
     75	.R[PSC_FAN] = 0,
     76	.m[PSC_TEMPERATURE] = 1,
     77	.b[PSC_TEMPERATURE] = 0,
     78	.R[PSC_TEMPERATURE] = 1,
     79	.m[PSC_VOLTAGE_IN] = 1,
     80	.b[PSC_VOLTAGE_IN] = 0,
     81	.R[PSC_VOLTAGE_IN] = 3,
     82	.func[0] = PMBUS_HAVE_TEMP | PMBUS_HAVE_TEMP2 | PMBUS_HAVE_TEMP3 |
     83		PMBUS_HAVE_VIN | PMBUS_HAVE_FAN12 | PMBUS_HAVE_FAN34 |
     84		PMBUS_HAVE_STATUS_FAN12 | PMBUS_HAVE_STATUS_FAN34 | PMBUS_PAGE_VIRTUAL,
     85	.func[1] = PMBUS_HAVE_TEMP | PMBUS_PAGE_VIRTUAL,
     86	.write_byte = ahe50dc_fan_write_byte,
     87	.read_word_data = ahe50dc_fan_read_word_data,
     88};
     89
     90/*
     91 * CAPABILITY returns 0xff, which appears to be this device's way indicating
     92 * it doesn't support something (and if we enable I2C_CLIENT_PEC on seeing bit
     93 * 7 being set it generates bad PECs, so let's not go there).
     94 */
     95static struct pmbus_platform_data ahe50dc_fan_data = {
     96	.flags = PMBUS_NO_CAPABILITY,
     97};
     98
     99static int ahe50dc_fan_probe(struct i2c_client *client)
    100{
    101	client->dev.platform_data = &ahe50dc_fan_data;
    102	return pmbus_do_probe(client, &ahe50dc_fan_info);
    103}
    104
    105static const struct i2c_device_id ahe50dc_fan_id[] = {
    106	{ "ahe50dc_fan" },
    107	{ }
    108};
    109MODULE_DEVICE_TABLE(i2c, ahe50dc_fan_id);
    110
    111static const struct of_device_id __maybe_unused ahe50dc_fan_of_match[] = {
    112	{ .compatible = "delta,ahe50dc-fan" },
    113	{ }
    114};
    115MODULE_DEVICE_TABLE(of, ahe50dc_fan_of_match);
    116
    117static struct i2c_driver ahe50dc_fan_driver = {
    118	.driver = {
    119		   .name = "ahe50dc_fan",
    120		   .of_match_table = of_match_ptr(ahe50dc_fan_of_match),
    121	},
    122	.probe_new = ahe50dc_fan_probe,
    123	.id_table = ahe50dc_fan_id,
    124};
    125module_i2c_driver(ahe50dc_fan_driver);
    126
    127MODULE_AUTHOR("Zev Weiss <zev@bewilderbeest.net>");
    128MODULE_DESCRIPTION("Driver for Delta AHE-50DC power shelf fan control module");
    129MODULE_LICENSE("GPL");
    130MODULE_IMPORT_NS(PMBUS);