1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * drivers/hwmon/nsa320-hwmon.c
4 *
5 * ZyXEL NSA320 Media Servers
6 * hardware monitoring
7 *
8 * Copyright (C) 2016 Adam Baker <linux@baker-net.org.uk>
9 * based on a board file driver
10 * Copyright (C) 2012 Peter Schildmann <linux@schildmann.info>
11 */
12
13#include <linux/bitops.h>
14#include <linux/delay.h>
15#include <linux/err.h>
16#include <linux/gpio/consumer.h>
17#include <linux/hwmon.h>
18#include <linux/hwmon-sysfs.h>
19#include <linux/jiffies.h>
20#include <linux/module.h>
21#include <linux/mutex.h>
22#include <linux/of.h>
23#include <linux/platform_device.h>
24
25/* Tests for error return values rely upon this value being < 0x80 */
26#define MAGIC_NUMBER 0x55
27
28/*
29 * The Zyxel hwmon MCU is a Holtek HT46R065 that is factory programmed
30 * to perform temperature and fan speed monitoring. It is read by taking
31 * the active pin low. The 32 bit output word is then clocked onto the
32 * data line. The MSB of the data word is a magic nuber to indicate it
33 * has been read correctly, the next byte is the fan speed (in hundreds
34 * of RPM) and the last two bytes are the temperature (in tenths of a
35 * degree)
36 */
37
38struct nsa320_hwmon {
39 struct mutex update_lock; /* lock GPIO operations */
40 unsigned long last_updated; /* jiffies */
41 unsigned long mcu_data;
42 struct gpio_desc *act;
43 struct gpio_desc *clk;
44 struct gpio_desc *data;
45};
46
47enum nsa320_inputs {
48 NSA320_TEMP = 0,
49 NSA320_FAN = 1,
50};
51
52static const char * const nsa320_input_names[] = {
53 [NSA320_TEMP] = "System Temperature",
54 [NSA320_FAN] = "Chassis Fan",
55};
56
57/*
58 * Although this protocol looks similar to SPI the long delay
59 * between the active (aka chip select) signal and the shorter
60 * delay between clock pulses are needed for reliable operation.
61 * The delays provided are taken from the manufacturer kernel,
62 * testing suggest they probably incorporate a reasonable safety
63 * margin. (The single device tested became unreliable if the
64 * delay was reduced to 1/10th of this value.)
65 */
66static s32 nsa320_hwmon_update(struct device *dev)
67{
68 u32 mcu_data;
69 u32 mask;
70 struct nsa320_hwmon *hwmon = dev_get_drvdata(dev);
71
72 mutex_lock(&hwmon->update_lock);
73
74 mcu_data = hwmon->mcu_data;
75
76 if (time_after(jiffies, hwmon->last_updated + HZ) || mcu_data == 0) {
77 gpiod_set_value(desc: hwmon->act, value: 1);
78 msleep(msecs: 100);
79
80 mcu_data = 0;
81 for (mask = BIT(31); mask; mask >>= 1) {
82 gpiod_set_value(desc: hwmon->clk, value: 0);
83 usleep_range(min: 100, max: 200);
84 gpiod_set_value(desc: hwmon->clk, value: 1);
85 usleep_range(min: 100, max: 200);
86 if (gpiod_get_value(desc: hwmon->data))
87 mcu_data |= mask;
88 }
89
90 gpiod_set_value(desc: hwmon->act, value: 0);
91 dev_dbg(dev, "Read raw MCU data %08x\n", mcu_data);
92
93 if ((mcu_data >> 24) != MAGIC_NUMBER) {
94 dev_dbg(dev, "Read invalid MCU data %08x\n", mcu_data);
95 mcu_data = -EIO;
96 } else {
97 hwmon->mcu_data = mcu_data;
98 hwmon->last_updated = jiffies;
99 }
100 }
101
102 mutex_unlock(lock: &hwmon->update_lock);
103
104 return mcu_data;
105}
106
107static ssize_t label_show(struct device *dev, struct device_attribute *attr,
108 char *buf)
109{
110 int channel = to_sensor_dev_attr(attr)->index;
111
112 return sprintf(buf, fmt: "%s\n", nsa320_input_names[channel]);
113}
114
115static ssize_t temp1_input_show(struct device *dev,
116 struct device_attribute *attr, char *buf)
117{
118 s32 mcu_data = nsa320_hwmon_update(dev);
119
120 if (mcu_data < 0)
121 return mcu_data;
122
123 return sprintf(buf, fmt: "%d\n", (mcu_data & 0xffff) * 100);
124}
125
126static ssize_t fan1_input_show(struct device *dev,
127 struct device_attribute *attr, char *buf)
128{
129 s32 mcu_data = nsa320_hwmon_update(dev);
130
131 if (mcu_data < 0)
132 return mcu_data;
133
134 return sprintf(buf, fmt: "%d\n", ((mcu_data & 0xff0000) >> 16) * 100);
135}
136
137static SENSOR_DEVICE_ATTR_RO(temp1_label, label, NSA320_TEMP);
138static DEVICE_ATTR_RO(temp1_input);
139static SENSOR_DEVICE_ATTR_RO(fan1_label, label, NSA320_FAN);
140static DEVICE_ATTR_RO(fan1_input);
141
142static struct attribute *nsa320_attrs[] = {
143 &sensor_dev_attr_temp1_label.dev_attr.attr,
144 &dev_attr_temp1_input.attr,
145 &sensor_dev_attr_fan1_label.dev_attr.attr,
146 &dev_attr_fan1_input.attr,
147 NULL
148};
149
150ATTRIBUTE_GROUPS(nsa320);
151
152static const struct of_device_id of_nsa320_hwmon_match[] = {
153 { .compatible = "zyxel,nsa320-mcu", },
154 { },
155};
156
157static int nsa320_hwmon_probe(struct platform_device *pdev)
158{
159 struct nsa320_hwmon *hwmon;
160 struct device *classdev;
161
162 hwmon = devm_kzalloc(dev: &pdev->dev, size: sizeof(*hwmon), GFP_KERNEL);
163 if (!hwmon)
164 return -ENOMEM;
165
166 /* Look up the GPIO pins to use */
167 hwmon->act = devm_gpiod_get(dev: &pdev->dev, con_id: "act", flags: GPIOD_OUT_LOW);
168 if (IS_ERR(ptr: hwmon->act))
169 return PTR_ERR(ptr: hwmon->act);
170
171 hwmon->clk = devm_gpiod_get(dev: &pdev->dev, con_id: "clk", flags: GPIOD_OUT_HIGH);
172 if (IS_ERR(ptr: hwmon->clk))
173 return PTR_ERR(ptr: hwmon->clk);
174
175 hwmon->data = devm_gpiod_get(dev: &pdev->dev, con_id: "data", flags: GPIOD_IN);
176 if (IS_ERR(ptr: hwmon->data))
177 return PTR_ERR(ptr: hwmon->data);
178
179 mutex_init(&hwmon->update_lock);
180
181 classdev = devm_hwmon_device_register_with_groups(dev: &pdev->dev,
182 name: "nsa320", drvdata: hwmon, groups: nsa320_groups);
183
184 return PTR_ERR_OR_ZERO(ptr: classdev);
185
186}
187
188/* All allocations use devres so remove() is not needed. */
189
190static struct platform_driver nsa320_hwmon_driver = {
191 .probe = nsa320_hwmon_probe,
192 .driver = {
193 .name = "nsa320-hwmon",
194 .of_match_table = of_nsa320_hwmon_match,
195 },
196};
197
198module_platform_driver(nsa320_hwmon_driver);
199
200MODULE_DEVICE_TABLE(of, of_nsa320_hwmon_match);
201MODULE_AUTHOR("Peter Schildmann <linux@schildmann.info>");
202MODULE_AUTHOR("Adam Baker <linux@baker-net.org.uk>");
203MODULE_DESCRIPTION("NSA320 Hardware Monitoring");
204MODULE_LICENSE("GPL v2");
205MODULE_ALIAS("platform:nsa320-hwmon");
206

source code of linux/drivers/hwmon/nsa320-hwmon.c