aboutsummaryrefslogtreecommitdiff
path: root/drivers/hwmon/nsa320-hwmon.c
blob: 0517a265741f16c2ef8fdaf7091519ea57979558 (plain)
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
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
/*
 * drivers/hwmon/nsa320-hwmon.c
 *
 * ZyXEL NSA320 Media Servers
 * hardware monitoring
 *
 * Copyright (C) 2016 Adam Baker <linux@baker-net.org.uk>
 * based on a board file driver
 * Copyright (C) 2012 Peter Schildmann <linux@schildmann.info>
 *
 * This program is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License v2 as published by the
 * Free Software Foundation.
 *
 * This program is distributed in the hope that it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
 * more details.
 */

#include <linux/bitops.h>
#include <linux/delay.h>
#include <linux/err.h>
#include <linux/gpio/consumer.h>
#include <linux/hwmon.h>
#include <linux/hwmon-sysfs.h>
#include <linux/jiffies.h>
#include <linux/module.h>
#include <linux/mutex.h>
#include <linux/of.h>
#include <linux/of_device.h>
#include <linux/of_platform.h>
#include <linux/platform_device.h>

/* Tests for error return values rely upon this value being < 0x80 */
#define MAGIC_NUMBER 0x55

/*
 * The Zyxel hwmon MCU is a Holtek HT46R065 that is factory programmed
 * to perform temperature and fan speed monitoring. It is read by taking
 * the active pin low. The 32 bit output word is then clocked onto the
 * data line. The MSB of the data word is a magic nuber to indicate it
 * has been read correctly, the next byte is the fan speed (in hundreds
 * of RPM) and the last two bytes are the temperature (in tenths of a
 * degree)
 */

struct nsa320_hwmon {
	struct mutex		update_lock;	/* lock GPIO operations */
	unsigned long		last_updated;	/* jiffies */
	unsigned long		mcu_data;
	struct gpio_desc	*act;
	struct gpio_desc	*clk;
	struct gpio_desc	*data;
};

enum nsa320_inputs {
	NSA320_TEMP = 0,
	NSA320_FAN = 1,
};

static const char * const nsa320_input_names[] = {
	[NSA320_TEMP] = "System Temperature",
	[NSA320_FAN] = "Chassis Fan",
};

/*
 * Although this protocol looks similar to SPI the long delay
 * between the active (aka chip select) signal and the shorter
 * delay between clock pulses are needed for reliable operation.
 * The delays provided are taken from the manufacturer kernel,
 * testing suggest they probably incorporate a reasonable safety
 * margin. (The single device tested became unreliable if the
 * delay was reduced to 1/10th of this value.)
 */
static s32 nsa320_hwmon_update(struct device *dev)
{
	u32 mcu_data;
	u32 mask;
	struct nsa320_hwmon *hwmon = dev_get_drvdata(dev);

	mutex_lock(&hwmon->update_lock);

	mcu_data = hwmon->mcu_data;

	if (time_after(jiffies, hwmon->last_updated + HZ) || mcu_data == 0) {
		gpiod_set_value(hwmon->act, 1);
		msleep(100);

		mcu_data = 0;
		for (mask = BIT(31); mask; mask >>= 1) {
			gpiod_set_value(hwmon->clk, 0);
			usleep_range(100, 200);
			gpiod_set_value(hwmon->clk, 1);
			usleep_range(100, 200);
			if (gpiod_get_value(hwmon->data))
				mcu_data |= mask;
		}

		gpiod_set_value(hwmon->act, 0);
		dev_dbg(dev, "Read raw MCU data %08x\n", mcu_data);

		if ((mcu_data >> 24) != MAGIC_NUMBER) {
			dev_dbg(dev, "Read invalid MCU data %08x\n", mcu_data);
			mcu_data = -EIO;
		} else {
			hwmon->mcu_data = mcu_data;
			hwmon->last_updated = jiffies;
		}
	}

	mutex_unlock(&hwmon->update_lock);

	return mcu_data;
}

static ssize_t show_label(struct device *dev,
			  struct device_attribute *attr, char *buf)
{
	int channel = to_sensor_dev_attr(attr)->index;

	return sprintf(buf, "%s\n", nsa320_input_names[channel]);
}

static ssize_t show_temp(struct device *dev, struct device_attribute *attr,
			 char *buf)
{
	s32 mcu_data = nsa320_hwmon_update(dev);

	if (mcu_data < 0)
		return mcu_data;

	return sprintf(buf, "%d\n", (mcu_data & 0xffff) * 100);
}

static ssize_t show_fan(struct device *dev, struct device_attribute *attr,
			char *buf)
{
	s32 mcu_data = nsa320_hwmon_update(dev);

	if (mcu_data < 0)
		return mcu_data;

	return sprintf(buf, "%d\n", ((mcu_data & 0xff0000) >> 16) * 100);
}

static SENSOR_DEVICE_ATTR(temp1_label, S_IRUGO, show_label, NULL, NSA320_TEMP);
static DEVICE_ATTR(temp1_input, S_IRUGO, show_temp, NULL);
static SENSOR_DEVICE_ATTR(fan1_label, S_IRUGO, show_label, NULL, NSA320_FAN);
static DEVICE_ATTR(fan1_input, S_IRUGO, show_fan, NULL);

static struct attribute *nsa320_attrs[] = {
	&sensor_dev_attr_temp1_label.dev_attr.attr,
	&dev_attr_temp1_input.attr,
	&sensor_dev_attr_fan1_label.dev_attr.attr,
	&dev_attr_fan1_input.attr,
	NULL
};

ATTRIBUTE_GROUPS(nsa320);

static const struct of_device_id of_nsa320_hwmon_match[] = {
	{ .compatible = "zyxel,nsa320-mcu", },
	{ },
};

static int nsa320_hwmon_probe(struct platform_device *pdev)
{
	struct nsa320_hwmon	*hwmon;
	struct device		*classdev;

	hwmon = devm_kzalloc(&pdev->dev, sizeof(*hwmon), GFP_KERNEL);
	if (!hwmon)
		return -ENOMEM;

	/* Look up the GPIO pins to use */
	hwmon->act = devm_gpiod_get(&pdev->dev, "act", GPIOD_OUT_LOW);
	if (IS_ERR(hwmon->act))
		return PTR_ERR(hwmon->act);

	hwmon->clk = devm_gpiod_get(&pdev->dev, "clk", GPIOD_OUT_HIGH);
	if (IS_ERR(hwmon->clk))
		return PTR_ERR(hwmon->clk);

	hwmon->data = devm_gpiod_get(&pdev->dev, "data", GPIOD_IN);
	if (IS_ERR(hwmon->data))
		return PTR_ERR(hwmon->data);

	mutex_init(&hwmon->update_lock);

	classdev = devm_hwmon_device_register_with_groups(&pdev->dev,
					"nsa320", hwmon, nsa320_groups);

	return PTR_ERR_OR_ZERO(classdev);

}

/* All allocations use devres so remove() is not needed. */

static struct platform_driver nsa320_hwmon_driver = {
	.probe = nsa320_hwmon_probe,
	.driver = {
		.name = "nsa320-hwmon",
		.of_match_table = of_match_ptr(of_nsa320_hwmon_match),
	},
};

module_platform_driver(nsa320_hwmon_driver);

MODULE_DEVICE_TABLE(of, of_nsa320_hwmon_match);
MODULE_AUTHOR("Peter Schildmann <linux@schildmann.info>");
MODULE_AUTHOR("Adam Baker <linux@baker-net.org.uk>");
MODULE_DESCRIPTION("NSA320 Hardware Monitoring");
MODULE_LICENSE("GPL v2");
MODULE_ALIAS("platform:nsa320-hwmon");