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/of_device.h>
24 #include <linux/of_platform.h>
25 #include <linux/platform_device.h>
26 
27 /* Tests for error return values rely upon this value being < 0x80 */
28 #define MAGIC_NUMBER 0x55
29 
30 /*
31  * The Zyxel hwmon MCU is a Holtek HT46R065 that is factory programmed
32  * to perform temperature and fan speed monitoring. It is read by taking
33  * the active pin low. The 32 bit output word is then clocked onto the
34  * data line. The MSB of the data word is a magic nuber to indicate it
35  * has been read correctly, the next byte is the fan speed (in hundreds
36  * of RPM) and the last two bytes are the temperature (in tenths of a
37  * degree)
38  */
39 
40 struct nsa320_hwmon {
41 	struct mutex		update_lock;	/* lock GPIO operations */
42 	unsigned long		last_updated;	/* jiffies */
43 	unsigned long		mcu_data;
44 	struct gpio_desc	*act;
45 	struct gpio_desc	*clk;
46 	struct gpio_desc	*data;
47 };
48 
49 enum nsa320_inputs {
50 	NSA320_TEMP = 0,
51 	NSA320_FAN = 1,
52 };
53 
54 static const char * const nsa320_input_names[] = {
55 	[NSA320_TEMP] = "System Temperature",
56 	[NSA320_FAN] = "Chassis Fan",
57 };
58 
59 /*
60  * Although this protocol looks similar to SPI the long delay
61  * between the active (aka chip select) signal and the shorter
62  * delay between clock pulses are needed for reliable operation.
63  * The delays provided are taken from the manufacturer kernel,
64  * testing suggest they probably incorporate a reasonable safety
65  * margin. (The single device tested became unreliable if the
66  * delay was reduced to 1/10th of this value.)
67  */
nsa320_hwmon_update(struct device * dev)68 static s32 nsa320_hwmon_update(struct device *dev)
69 {
70 	u32 mcu_data;
71 	u32 mask;
72 	struct nsa320_hwmon *hwmon = dev_get_drvdata(dev);
73 
74 	mutex_lock(&hwmon->update_lock);
75 
76 	mcu_data = hwmon->mcu_data;
77 
78 	if (time_after(jiffies, hwmon->last_updated + HZ) || mcu_data == 0) {
79 		gpiod_set_value(hwmon->act, 1);
80 		msleep(100);
81 
82 		mcu_data = 0;
83 		for (mask = BIT(31); mask; mask >>= 1) {
84 			gpiod_set_value(hwmon->clk, 0);
85 			usleep_range(100, 200);
86 			gpiod_set_value(hwmon->clk, 1);
87 			usleep_range(100, 200);
88 			if (gpiod_get_value(hwmon->data))
89 				mcu_data |= mask;
90 		}
91 
92 		gpiod_set_value(hwmon->act, 0);
93 		dev_dbg(dev, "Read raw MCU data %08x\n", mcu_data);
94 
95 		if ((mcu_data >> 24) != MAGIC_NUMBER) {
96 			dev_dbg(dev, "Read invalid MCU data %08x\n", mcu_data);
97 			mcu_data = -EIO;
98 		} else {
99 			hwmon->mcu_data = mcu_data;
100 			hwmon->last_updated = jiffies;
101 		}
102 	}
103 
104 	mutex_unlock(&hwmon->update_lock);
105 
106 	return mcu_data;
107 }
108 
label_show(struct device * dev,struct device_attribute * attr,char * buf)109 static ssize_t label_show(struct device *dev, struct device_attribute *attr,
110 			  char *buf)
111 {
112 	int channel = to_sensor_dev_attr(attr)->index;
113 
114 	return sprintf(buf, "%s\n", nsa320_input_names[channel]);
115 }
116 
temp1_input_show(struct device * dev,struct device_attribute * attr,char * buf)117 static ssize_t temp1_input_show(struct device *dev,
118 				struct device_attribute *attr, char *buf)
119 {
120 	s32 mcu_data = nsa320_hwmon_update(dev);
121 
122 	if (mcu_data < 0)
123 		return mcu_data;
124 
125 	return sprintf(buf, "%d\n", (mcu_data & 0xffff) * 100);
126 }
127 
fan1_input_show(struct device * dev,struct device_attribute * attr,char * buf)128 static ssize_t fan1_input_show(struct device *dev,
129 			       struct device_attribute *attr, char *buf)
130 {
131 	s32 mcu_data = nsa320_hwmon_update(dev);
132 
133 	if (mcu_data < 0)
134 		return mcu_data;
135 
136 	return sprintf(buf, "%d\n", ((mcu_data & 0xff0000) >> 16) * 100);
137 }
138 
139 static SENSOR_DEVICE_ATTR_RO(temp1_label, label, NSA320_TEMP);
140 static DEVICE_ATTR_RO(temp1_input);
141 static SENSOR_DEVICE_ATTR_RO(fan1_label, label, NSA320_FAN);
142 static DEVICE_ATTR_RO(fan1_input);
143 
144 static struct attribute *nsa320_attrs[] = {
145 	&sensor_dev_attr_temp1_label.dev_attr.attr,
146 	&dev_attr_temp1_input.attr,
147 	&sensor_dev_attr_fan1_label.dev_attr.attr,
148 	&dev_attr_fan1_input.attr,
149 	NULL
150 };
151 
152 ATTRIBUTE_GROUPS(nsa320);
153 
154 static const struct of_device_id of_nsa320_hwmon_match[] = {
155 	{ .compatible = "zyxel,nsa320-mcu", },
156 	{ },
157 };
158 
nsa320_hwmon_probe(struct platform_device * pdev)159 static int nsa320_hwmon_probe(struct platform_device *pdev)
160 {
161 	struct nsa320_hwmon	*hwmon;
162 	struct device		*classdev;
163 
164 	hwmon = devm_kzalloc(&pdev->dev, sizeof(*hwmon), GFP_KERNEL);
165 	if (!hwmon)
166 		return -ENOMEM;
167 
168 	/* Look up the GPIO pins to use */
169 	hwmon->act = devm_gpiod_get(&pdev->dev, "act", GPIOD_OUT_LOW);
170 	if (IS_ERR(hwmon->act))
171 		return PTR_ERR(hwmon->act);
172 
173 	hwmon->clk = devm_gpiod_get(&pdev->dev, "clk", GPIOD_OUT_HIGH);
174 	if (IS_ERR(hwmon->clk))
175 		return PTR_ERR(hwmon->clk);
176 
177 	hwmon->data = devm_gpiod_get(&pdev->dev, "data", GPIOD_IN);
178 	if (IS_ERR(hwmon->data))
179 		return PTR_ERR(hwmon->data);
180 
181 	mutex_init(&hwmon->update_lock);
182 
183 	classdev = devm_hwmon_device_register_with_groups(&pdev->dev,
184 					"nsa320", hwmon, nsa320_groups);
185 
186 	return PTR_ERR_OR_ZERO(classdev);
187 
188 }
189 
190 /* All allocations use devres so remove() is not needed. */
191 
192 static struct platform_driver nsa320_hwmon_driver = {
193 	.probe = nsa320_hwmon_probe,
194 	.driver = {
195 		.name = "nsa320-hwmon",
196 		.of_match_table = of_match_ptr(of_nsa320_hwmon_match),
197 	},
198 };
199 
200 module_platform_driver(nsa320_hwmon_driver);
201 
202 MODULE_DEVICE_TABLE(of, of_nsa320_hwmon_match);
203 MODULE_AUTHOR("Peter Schildmann <linux@schildmann.info>");
204 MODULE_AUTHOR("Adam Baker <linux@baker-net.org.uk>");
205 MODULE_DESCRIPTION("NSA320 Hardware Monitoring");
206 MODULE_LICENSE("GPL v2");
207 MODULE_ALIAS("platform:nsa320-hwmon");
208