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); 131