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
ahe50dc_fan_write_byte(struct i2c_client * client,int page,u8 value)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
ahe50dc_fan_read_word_data(struct i2c_client * client,int page,int phase,int reg)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
ahe50dc_fan_probe(struct i2c_client * client)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_new = 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