drivers/hwmon/pmbus/delta-ahe50dc-fan.c

   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
  17 static 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
  32 static 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
  68 static 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  */
  95 static struct pmbus_platform_data ahe50dc_fan_data = {
  96         .flags = PMBUS_NO_CAPABILITY,
  97 };
  98
  99 static 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
 105 static const struct i2c_device_id ahe50dc_fan_id[] = {
 106         { "ahe50dc_fan" },
 107         { }
 108 };
 109 MODULE_DEVICE_TABLE(i2c, ahe50dc_fan_id);
 110
 111 static const struct of_device_id __maybe_unused ahe50dc_fan_of_match[] = {
 112         { .compatible = "delta,ahe50dc-fan" },
 113         { }
 114 };
 115 MODULE_DEVICE_TABLE(of, ahe50dc_fan_of_match);
 116
 117 static 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 = ahe50dc_fan_probe,
 123         .id_table = ahe50dc_fan_id,
 124 };
 125 module_i2c_driver(ahe50dc_fan_driver);
 126
 127 MODULE_AUTHOR("Zev Weiss <zev@bewilderbeest.net>");
 128 MODULE_DESCRIPTION("Driver for Delta AHE-50DC power shelf fan control module");
 129 MODULE_LICENSE("GPL");
 130 MODULE_IMPORT_NS("PMBUS");