xref: /openbmc/linux/drivers/hwmon/max197.c (revision d2912cb1)
1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3  * Maxim MAX197 A/D Converter driver
4  *
5  * Copyright (c) 2012 Savoir-faire Linux Inc.
6  *          Vivien Didelot <vivien.didelot@savoirfairelinux.com>
7  *
8  * For further information, see the Documentation/hwmon/max197.rst file.
9  */
10 
11 #include <linux/kernel.h>
12 #include <linux/module.h>
13 #include <linux/mod_devicetable.h>
14 #include <linux/init.h>
15 #include <linux/err.h>
16 #include <linux/slab.h>
17 #include <linux/mutex.h>
18 #include <linux/device.h>
19 #include <linux/sysfs.h>
20 #include <linux/hwmon.h>
21 #include <linux/hwmon-sysfs.h>
22 #include <linux/platform_device.h>
23 #include <linux/platform_data/max197.h>
24 
25 #define MAX199_LIMIT	4000		/* 4V */
26 #define MAX197_LIMIT	10000		/* 10V */
27 
28 #define MAX197_NUM_CH	8		/* 8 Analog Input Channels */
29 
30 /* Control byte format */
31 #define MAX197_BIP	(1 << 3)	/* Bipolarity */
32 #define MAX197_RNG	(1 << 4)	/* Full range */
33 
34 #define MAX197_SCALE	12207		/* Scale coefficient for raw data */
35 
36 /* List of supported chips */
37 enum max197_chips { max197, max199 };
38 
39 /**
40  * struct max197_data - device instance specific data
41  * @pdata:		Platform data.
42  * @hwmon_dev:		The hwmon device.
43  * @lock:		Read/Write mutex.
44  * @limit:		Max range value (10V for MAX197, 4V for MAX199).
45  * @scale:		Need to scale.
46  * @ctrl_bytes:		Channels control byte.
47  */
48 struct max197_data {
49 	struct max197_platform_data *pdata;
50 	struct device *hwmon_dev;
51 	struct mutex lock;
52 	int limit;
53 	bool scale;
54 	u8 ctrl_bytes[MAX197_NUM_CH];
55 };
56 
max197_set_unipolarity(struct max197_data * data,int channel)57 static inline void max197_set_unipolarity(struct max197_data *data, int channel)
58 {
59 	data->ctrl_bytes[channel] &= ~MAX197_BIP;
60 }
61 
max197_set_bipolarity(struct max197_data * data,int channel)62 static inline void max197_set_bipolarity(struct max197_data *data, int channel)
63 {
64 	data->ctrl_bytes[channel] |= MAX197_BIP;
65 }
66 
max197_set_half_range(struct max197_data * data,int channel)67 static inline void max197_set_half_range(struct max197_data *data, int channel)
68 {
69 	data->ctrl_bytes[channel] &= ~MAX197_RNG;
70 }
71 
max197_set_full_range(struct max197_data * data,int channel)72 static inline void max197_set_full_range(struct max197_data *data, int channel)
73 {
74 	data->ctrl_bytes[channel] |= MAX197_RNG;
75 }
76 
max197_is_bipolar(struct max197_data * data,int channel)77 static inline bool max197_is_bipolar(struct max197_data *data, int channel)
78 {
79 	return data->ctrl_bytes[channel] & MAX197_BIP;
80 }
81 
max197_is_full_range(struct max197_data * data,int channel)82 static inline bool max197_is_full_range(struct max197_data *data, int channel)
83 {
84 	return data->ctrl_bytes[channel] & MAX197_RNG;
85 }
86 
87 /* Function called on read access on in{0,1,2,3,4,5,6,7}_{min,max} */
max197_show_range(struct device * dev,struct device_attribute * devattr,char * buf)88 static ssize_t max197_show_range(struct device *dev,
89 				 struct device_attribute *devattr, char *buf)
90 {
91 	struct max197_data *data = dev_get_drvdata(dev);
92 	struct sensor_device_attribute_2 *attr = to_sensor_dev_attr_2(devattr);
93 	int channel = attr->index;
94 	bool is_min = attr->nr;
95 	int range;
96 
97 	if (mutex_lock_interruptible(&data->lock))
98 		return -ERESTARTSYS;
99 
100 	range = max197_is_full_range(data, channel) ?
101 		data->limit : data->limit / 2;
102 	if (is_min) {
103 		if (max197_is_bipolar(data, channel))
104 			range = -range;
105 		else
106 			range = 0;
107 	}
108 
109 	mutex_unlock(&data->lock);
110 
111 	return sprintf(buf, "%d\n", range);
112 }
113 
114 /* Function called on write access on in{0,1,2,3,4,5,6,7}_{min,max} */
max197_store_range(struct device * dev,struct device_attribute * devattr,const char * buf,size_t count)115 static ssize_t max197_store_range(struct device *dev,
116 				  struct device_attribute *devattr,
117 				  const char *buf, size_t count)
118 {
119 	struct max197_data *data = dev_get_drvdata(dev);
120 	struct sensor_device_attribute_2 *attr = to_sensor_dev_attr_2(devattr);
121 	int channel = attr->index;
122 	bool is_min = attr->nr;
123 	long value;
124 	int half = data->limit / 2;
125 	int full = data->limit;
126 
127 	if (kstrtol(buf, 10, &value))
128 		return -EINVAL;
129 
130 	if (is_min) {
131 		if (value <= -full)
132 			value = -full;
133 		else if (value < 0)
134 			value = -half;
135 		else
136 			value = 0;
137 	} else {
138 		if (value >= full)
139 			value = full;
140 		else
141 			value = half;
142 	}
143 
144 	if (mutex_lock_interruptible(&data->lock))
145 		return -ERESTARTSYS;
146 
147 	if (value == 0) {
148 		/* We can deduce only the polarity */
149 		max197_set_unipolarity(data, channel);
150 	} else if (value == -half) {
151 		max197_set_bipolarity(data, channel);
152 		max197_set_half_range(data, channel);
153 	} else if (value == -full) {
154 		max197_set_bipolarity(data, channel);
155 		max197_set_full_range(data, channel);
156 	} else if (value == half) {
157 		/* We can deduce only the range */
158 		max197_set_half_range(data, channel);
159 	} else if (value == full) {
160 		/* We can deduce only the range */
161 		max197_set_full_range(data, channel);
162 	}
163 
164 	mutex_unlock(&data->lock);
165 
166 	return count;
167 }
168 
169 /* Function called on read access on in{0,1,2,3,4,5,6,7}_input */
max197_show_input(struct device * dev,struct device_attribute * devattr,char * buf)170 static ssize_t max197_show_input(struct device *dev,
171 				 struct device_attribute *devattr,
172 				 char *buf)
173 {
174 	struct max197_data *data = dev_get_drvdata(dev);
175 	struct sensor_device_attribute *attr = to_sensor_dev_attr(devattr);
176 	int channel = attr->index;
177 	s32 value;
178 	int ret;
179 
180 	if (mutex_lock_interruptible(&data->lock))
181 		return -ERESTARTSYS;
182 
183 	ret = data->pdata->convert(data->ctrl_bytes[channel]);
184 	if (ret < 0) {
185 		dev_err(dev, "conversion failed\n");
186 		goto unlock;
187 	}
188 	value = ret;
189 
190 	/*
191 	 * Coefficient to apply on raw value.
192 	 * See Table 1. Full Scale and Zero Scale in the MAX197 datasheet.
193 	 */
194 	if (data->scale) {
195 		value *= MAX197_SCALE;
196 		if (max197_is_full_range(data, channel))
197 			value *= 2;
198 		value /= 10000;
199 	}
200 
201 	ret = sprintf(buf, "%d\n", value);
202 
203 unlock:
204 	mutex_unlock(&data->lock);
205 	return ret;
206 }
207 
name_show(struct device * dev,struct device_attribute * attr,char * buf)208 static ssize_t name_show(struct device *dev, struct device_attribute *attr,
209 			 char *buf)
210 {
211 	struct platform_device *pdev = to_platform_device(dev);
212 	return sprintf(buf, "%s\n", pdev->name);
213 }
214 
215 #define MAX197_SENSOR_DEVICE_ATTR_CH(chan)				\
216 	static SENSOR_DEVICE_ATTR(in##chan##_input, S_IRUGO,		\
217 				  max197_show_input, NULL, chan);	\
218 	static SENSOR_DEVICE_ATTR_2(in##chan##_min, S_IRUGO | S_IWUSR,	\
219 				    max197_show_range,			\
220 				    max197_store_range,			\
221 				    true, chan);			\
222 	static SENSOR_DEVICE_ATTR_2(in##chan##_max, S_IRUGO | S_IWUSR,	\
223 				    max197_show_range,			\
224 				    max197_store_range,			\
225 				    false, chan)
226 
227 #define MAX197_SENSOR_DEV_ATTR_IN(chan)					\
228 	&sensor_dev_attr_in##chan##_input.dev_attr.attr,		\
229 	&sensor_dev_attr_in##chan##_max.dev_attr.attr,			\
230 	&sensor_dev_attr_in##chan##_min.dev_attr.attr
231 
232 static DEVICE_ATTR_RO(name);
233 
234 MAX197_SENSOR_DEVICE_ATTR_CH(0);
235 MAX197_SENSOR_DEVICE_ATTR_CH(1);
236 MAX197_SENSOR_DEVICE_ATTR_CH(2);
237 MAX197_SENSOR_DEVICE_ATTR_CH(3);
238 MAX197_SENSOR_DEVICE_ATTR_CH(4);
239 MAX197_SENSOR_DEVICE_ATTR_CH(5);
240 MAX197_SENSOR_DEVICE_ATTR_CH(6);
241 MAX197_SENSOR_DEVICE_ATTR_CH(7);
242 
243 static const struct attribute_group max197_sysfs_group = {
244 	.attrs = (struct attribute *[]) {
245 		&dev_attr_name.attr,
246 		MAX197_SENSOR_DEV_ATTR_IN(0),
247 		MAX197_SENSOR_DEV_ATTR_IN(1),
248 		MAX197_SENSOR_DEV_ATTR_IN(2),
249 		MAX197_SENSOR_DEV_ATTR_IN(3),
250 		MAX197_SENSOR_DEV_ATTR_IN(4),
251 		MAX197_SENSOR_DEV_ATTR_IN(5),
252 		MAX197_SENSOR_DEV_ATTR_IN(6),
253 		MAX197_SENSOR_DEV_ATTR_IN(7),
254 		NULL
255 	},
256 };
257 
max197_probe(struct platform_device * pdev)258 static int max197_probe(struct platform_device *pdev)
259 {
260 	int ch, ret;
261 	struct max197_data *data;
262 	struct max197_platform_data *pdata = dev_get_platdata(&pdev->dev);
263 	enum max197_chips chip = platform_get_device_id(pdev)->driver_data;
264 
265 	if (pdata == NULL) {
266 		dev_err(&pdev->dev, "no platform data supplied\n");
267 		return -EINVAL;
268 	}
269 
270 	if (pdata->convert == NULL) {
271 		dev_err(&pdev->dev, "no convert function supplied\n");
272 		return -EINVAL;
273 	}
274 
275 	data = devm_kzalloc(&pdev->dev, sizeof(struct max197_data), GFP_KERNEL);
276 	if (!data)
277 		return -ENOMEM;
278 
279 	data->pdata = pdata;
280 	mutex_init(&data->lock);
281 
282 	if (chip == max197) {
283 		data->limit = MAX197_LIMIT;
284 		data->scale = true;
285 	} else {
286 		data->limit = MAX199_LIMIT;
287 		data->scale = false;
288 	}
289 
290 	for (ch = 0; ch < MAX197_NUM_CH; ch++)
291 		data->ctrl_bytes[ch] = (u8) ch;
292 
293 	platform_set_drvdata(pdev, data);
294 
295 	ret = sysfs_create_group(&pdev->dev.kobj, &max197_sysfs_group);
296 	if (ret) {
297 		dev_err(&pdev->dev, "sysfs create group failed\n");
298 		return ret;
299 	}
300 
301 	data->hwmon_dev = hwmon_device_register(&pdev->dev);
302 	if (IS_ERR(data->hwmon_dev)) {
303 		ret = PTR_ERR(data->hwmon_dev);
304 		dev_err(&pdev->dev, "hwmon device register failed\n");
305 		goto error;
306 	}
307 
308 	return 0;
309 
310 error:
311 	sysfs_remove_group(&pdev->dev.kobj, &max197_sysfs_group);
312 	return ret;
313 }
314 
max197_remove(struct platform_device * pdev)315 static int max197_remove(struct platform_device *pdev)
316 {
317 	struct max197_data *data = platform_get_drvdata(pdev);
318 
319 	hwmon_device_unregister(data->hwmon_dev);
320 	sysfs_remove_group(&pdev->dev.kobj, &max197_sysfs_group);
321 
322 	return 0;
323 }
324 
325 static const struct platform_device_id max197_device_ids[] = {
326 	{ "max197", max197 },
327 	{ "max199", max199 },
328 	{ }
329 };
330 MODULE_DEVICE_TABLE(platform, max197_device_ids);
331 
332 static struct platform_driver max197_driver = {
333 	.driver = {
334 		.name = "max197",
335 	},
336 	.probe = max197_probe,
337 	.remove = max197_remove,
338 	.id_table = max197_device_ids,
339 };
340 module_platform_driver(max197_driver);
341 
342 MODULE_LICENSE("GPL");
343 MODULE_AUTHOR("Savoir-faire Linux Inc. <kernel@savoirfairelinux.com>");
344 MODULE_DESCRIPTION("Maxim MAX197 A/D Converter driver");
345