1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
|
// SPDX-License-Identifier: GPL-2.0
/*
* nct6775-i2c - I2C driver for the hardware monitoring functionality of
* Nuvoton NCT677x Super-I/O chips
*
* Copyright (C) 2022 Zev Weiss <zev@bewilderbeest.net>
*
* This driver interacts with the chip via it's "back door" i2c interface, as
* is often exposed to a BMC. Because the host may still be operating the
* chip via the ("front door") LPC interface, this driver cannot assume that
* it actually has full control of the chip, and in particular must avoid
* making any changes that could confuse the host's LPC usage of it. It thus
* operates in a strictly read-only fashion, with the only exception being the
* bank-select register (which seems, thankfully, to be replicated for the i2c
* interface so it doesn't affect the LPC interface).
*/
#include <linux/module.h>
#include <linux/init.h>
#include <linux/i2c.h>
#include <linux/hwmon.h>
#include <linux/hwmon-sysfs.h>
#include <linux/err.h>
#include <linux/of_device.h>
#include <linux/regmap.h>
#include "nct6775.h"
static int nct6775_i2c_read(void *ctx, unsigned int reg, unsigned int *val)
{
int ret;
u32 tmp;
u8 bank = reg >> 8;
struct nct6775_data *data = ctx;
struct i2c_client *client = data->driver_data;
if (bank != data->bank) {
ret = i2c_smbus_write_byte_data(client, NCT6775_REG_BANK, bank);
if (ret)
return ret;
data->bank = bank;
}
ret = i2c_smbus_read_byte_data(client, reg & 0xff);
if (ret < 0)
return ret;
tmp = ret;
if (nct6775_reg_is_word_sized(data, reg)) {
ret = i2c_smbus_read_byte_data(client, (reg & 0xff) + 1);
if (ret < 0)
return ret;
tmp = (tmp << 8) | ret;
}
*val = tmp;
return 0;
}
/*
* The write operation is a dummy so as not to disturb anything being done
* with the chip via LPC.
*/
static int nct6775_i2c_write(void *ctx, unsigned int reg, unsigned int value)
{
struct nct6775_data *data = ctx;
struct i2c_client *client = data->driver_data;
dev_dbg(&client->dev, "skipping attempted write: %02x -> %03x\n", value, reg);
/*
* This is a lie, but writing anything but the bank-select register is
* something this driver shouldn't be doing.
*/
return 0;
}
static const struct of_device_id __maybe_unused nct6775_i2c_of_match[] = {
{ .compatible = "nuvoton,nct6106", .data = (void *)nct6106, },
{ .compatible = "nuvoton,nct6116", .data = (void *)nct6116, },
{ .compatible = "nuvoton,nct6775", .data = (void *)nct6775, },
{ .compatible = "nuvoton,nct6776", .data = (void *)nct6776, },
{ .compatible = "nuvoton,nct6779", .data = (void *)nct6779, },
{ .compatible = "nuvoton,nct6791", .data = (void *)nct6791, },
{ .compatible = "nuvoton,nct6792", .data = (void *)nct6792, },
{ .compatible = "nuvoton,nct6793", .data = (void *)nct6793, },
{ .compatible = "nuvoton,nct6795", .data = (void *)nct6795, },
{ .compatible = "nuvoton,nct6796", .data = (void *)nct6796, },
{ .compatible = "nuvoton,nct6797", .data = (void *)nct6797, },
{ .compatible = "nuvoton,nct6798", .data = (void *)nct6798, },
{ },
};
MODULE_DEVICE_TABLE(of, nct6775_i2c_of_match);
static const struct i2c_device_id nct6775_i2c_id[] = {
{ "nct6106", nct6106 },
{ "nct6116", nct6116 },
{ "nct6775", nct6775 },
{ "nct6776", nct6776 },
{ "nct6779", nct6779 },
{ "nct6791", nct6791 },
{ "nct6792", nct6792 },
{ "nct6793", nct6793 },
{ "nct6795", nct6795 },
{ "nct6796", nct6796 },
{ "nct6797", nct6797 },
{ "nct6798", nct6798 },
{ }
};
MODULE_DEVICE_TABLE(i2c, nct6775_i2c_id);
static int nct6775_i2c_probe_init(struct nct6775_data *data)
{
u32 tsi_channel_mask;
struct i2c_client *client = data->driver_data;
/*
* The i2c interface doesn't provide access to the control registers
* needed to determine the presence of other fans, but fans 1 and 2
* are (in principle) always there.
*
* In practice this is perhaps a little silly, because the system
* using this driver is mostly likely a BMC, and hence probably has
* totally separate fan tachs & pwms of its own that are actually
* controlling/monitoring the fans -- these are thus unlikely to be
* doing anything actually useful.
*/
data->has_fan = 0x03;
data->has_fan_min = 0x03;
data->has_pwm = 0x03;
/*
* Because on a BMC this driver may be bound very shortly after power
* is first applied to the device, the automatic TSI channel detection
* in nct6775_probe() (which has already been run at this point) may
* not find anything if a channel hasn't yet produced a temperature
* reading. Augment whatever was found via autodetection (if
* anything) with the channels DT says should be active.
*/
if (!of_property_read_u32(client->dev.of_node, "nuvoton,tsi-channel-mask",
&tsi_channel_mask))
data->have_tsi_temp |= tsi_channel_mask & GENMASK(NUM_TSI_TEMP - 1, 0);
return 0;
}
static const struct regmap_config nct6775_i2c_regmap_config = {
.reg_bits = 16,
.val_bits = 16,
.reg_read = nct6775_i2c_read,
.reg_write = nct6775_i2c_write,
};
static int nct6775_i2c_probe(struct i2c_client *client)
{
struct nct6775_data *data;
const struct of_device_id *of_id;
const struct i2c_device_id *i2c_id;
struct device *dev = &client->dev;
of_id = of_match_device(nct6775_i2c_of_match, dev);
i2c_id = i2c_match_id(nct6775_i2c_id, client);
if (of_id && (unsigned long)of_id->data != i2c_id->driver_data)
dev_notice(dev, "Device mismatch: %s in device tree, %s detected\n",
of_id->name, i2c_id->name);
data = devm_kzalloc(&client->dev, sizeof(*data), GFP_KERNEL);
if (!data)
return -ENOMEM;
data->kind = i2c_id->driver_data;
data->read_only = true;
data->driver_data = client;
data->driver_init = nct6775_i2c_probe_init;
return nct6775_probe(dev, data, &nct6775_i2c_regmap_config);
}
static struct i2c_driver nct6775_i2c_driver = {
.class = I2C_CLASS_HWMON,
.driver = {
.name = "nct6775-i2c",
.of_match_table = of_match_ptr(nct6775_i2c_of_match),
},
.probe_new = nct6775_i2c_probe,
.id_table = nct6775_i2c_id,
};
module_i2c_driver(nct6775_i2c_driver);
MODULE_AUTHOR("Zev Weiss <zev@bewilderbeest.net>");
MODULE_DESCRIPTION("I2C driver for NCT6775F and compatible chips");
MODULE_LICENSE("GPL");
MODULE_IMPORT_NS(HWMON_NCT6775);
|
