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 | |
38 | struct 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 | |
47 | enum nsa320_inputs { |
48 | NSA320_TEMP = 0, |
49 | NSA320_FAN = 1, |
50 | }; |
51 | |
52 | static 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 | */ |
66 | static 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 | |
107 | static 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 | |
115 | static 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 | |
126 | static 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 | |
137 | static SENSOR_DEVICE_ATTR_RO(temp1_label, label, NSA320_TEMP); |
138 | static DEVICE_ATTR_RO(temp1_input); |
139 | static SENSOR_DEVICE_ATTR_RO(fan1_label, label, NSA320_FAN); |
140 | static DEVICE_ATTR_RO(fan1_input); |
141 | |
142 | static 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 | |
150 | ATTRIBUTE_GROUPS(nsa320); |
151 | |
152 | static const struct of_device_id of_nsa320_hwmon_match[] = { |
153 | { .compatible = "zyxel,nsa320-mcu" , }, |
154 | { }, |
155 | }; |
156 | |
157 | static 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 | |
190 | static 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 | |
198 | module_platform_driver(nsa320_hwmon_driver); |
199 | |
200 | MODULE_DEVICE_TABLE(of, of_nsa320_hwmon_match); |
201 | MODULE_AUTHOR("Peter Schildmann <linux@schildmann.info>" ); |
202 | MODULE_AUTHOR("Adam Baker <linux@baker-net.org.uk>" ); |
203 | MODULE_DESCRIPTION("NSA320 Hardware Monitoring" ); |
204 | MODULE_LICENSE("GPL v2" ); |
205 | MODULE_ALIAS("platform:nsa320-hwmon" ); |
206 | |