xref: /openbmc/linux/drivers/hwmon/max197.c (revision bc5aa3a0) 
1 /*
2  * Maxim MAX197 A/D Converter driver
3  *
4  * Copyright (c) 2012 Savoir-faire Linux Inc.
5  *          Vivien Didelot <vivien.didelot@savoirfairelinux.com>
6  *
7  * This program is free software; you can redistribute it and/or modify
8  * it under the terms of the GNU General Public License version 2 as
9  * published by the Free Software Foundation.
10  *
11  * For further information, see the Documentation/hwmon/max197 file.
12  */
13 
14 #include <linux/kernel.h>
15 #include <linux/module.h>
16 #include <linux/init.h>
17 #include <linux/err.h>
18 #include <linux/slab.h>
19 #include <linux/mutex.h>
20 #include <linux/device.h>
21 #include <linux/sysfs.h>
22 #include <linux/hwmon.h>
23 #include <linux/hwmon-sysfs.h>
24 #include <linux/platform_device.h>
25 #include <linux/platform_data/max197.h>
26 
27 #define MAX199_LIMIT	4000		/* 4V */
28 #define MAX197_LIMIT	10000		/* 10V */
29 
30 #define MAX197_NUM_CH	8		/* 8 Analog Input Channels */
31 
32 /* Control byte format */
33 #define MAX197_BIP	(1 << 3)	/* Bipolarity */
34 #define MAX197_RNG	(1 << 4)	/* Full range */
35 
36 #define MAX197_SCALE	12207		/* Scale coefficient for raw data */
37 
38 /* List of supported chips */
39 enum max197_chips { max197, max199 };
40 
41 /**
42  * struct max197_data - device instance specific data
43  * @pdata:		Platform data.
44  * @hwmon_dev:		The hwmon device.
45  * @lock:		Read/Write mutex.
46  * @limit:		Max range value (10V for MAX197, 4V for MAX199).
47  * @scale:		Need to scale.
48  * @ctrl_bytes:		Channels control byte.
49  */
50 struct max197_data {
51 	struct max197_platform_data *pdata;
52 	struct device *hwmon_dev;
53 	struct mutex lock;
54 	int limit;
55 	bool scale;
56 	u8 ctrl_bytes[MAX197_NUM_CH];
57 };
58 
59 static inline void max197_set_unipolarity(struct max197_data *data, int channel)
60 {
61 	data->ctrl_bytes[channel] &= ~MAX197_BIP;
62 }
63 
64 static inline void max197_set_bipolarity(struct max197_data *data, int channel)
65 {
66 	data->ctrl_bytes[channel] |= MAX197_BIP;
67 }
68 
69 static inline void max197_set_half_range(struct max197_data *data, int channel)
70 {
71 	data->ctrl_bytes[channel] &= ~MAX197_RNG;
72 }
73 
74 static inline void max197_set_full_range(struct max197_data *data, int channel)
75 {
76 	data->ctrl_bytes[channel] |= MAX197_RNG;
77 }
78 
79 static inline bool max197_is_bipolar(struct max197_data *data, int channel)
80 {
81 	return data->ctrl_bytes[channel] & MAX197_BIP;
82 }
83 
84 static inline bool max197_is_full_range(struct max197_data *data, int channel)
85 {
86 	return data->ctrl_bytes[channel] & MAX197_RNG;
87 }
88 
89 /* Function called on read access on in{0,1,2,3,4,5,6,7}_{min,max} */
90 static ssize_t max197_show_range(struct device *dev,
91 				 struct device_attribute *devattr, char *buf)
92 {
93 	struct max197_data *data = dev_get_drvdata(dev);
94 	struct sensor_device_attribute_2 *attr = to_sensor_dev_attr_2(devattr);
95 	int channel = attr->index;
96 	bool is_min = attr->nr;
97 	int range;
98 
99 	if (mutex_lock_interruptible(&data->lock))
100 		return -ERESTARTSYS;
101 
102 	range = max197_is_full_range(data, channel) ?
103 		data->limit : data->limit / 2;
104 	if (is_min) {
105 		if (max197_is_bipolar(data, channel))
106 			range = -range;
107 		else
108 			range = 0;
109 	}
110 
111 	mutex_unlock(&data->lock);
112 
113 	return sprintf(buf, "%d\n", range);
114 }
115 
116 /* Function called on write access on in{0,1,2,3,4,5,6,7}_{min,max} */
117 static ssize_t max197_store_range(struct device *dev,
118 				  struct device_attribute *devattr,
119 				  const char *buf, size_t count)
120 {
121 	struct max197_data *data = dev_get_drvdata(dev);
122 	struct sensor_device_attribute_2 *attr = to_sensor_dev_attr_2(devattr);
123 	int channel = attr->index;
124 	bool is_min = attr->nr;
125 	long value;
126 	int half = data->limit / 2;
127 	int full = data->limit;
128 
129 	if (kstrtol(buf, 10, &value))
130 		return -EINVAL;
131 
132 	if (is_min) {
133 		if (value <= -full)
134 			value = -full;
135 		else if (value < 0)
136 			value = -half;
137 		else
138 			value = 0;
139 	} else {
140 		if (value >= full)
141 			value = full;
142 		else
143 			value = half;
144 	}
145 
146 	if (mutex_lock_interruptible(&data->lock))
147 		return -ERESTARTSYS;
148 
149 	if (value == 0) {
150 		/* We can deduce only the polarity */
151 		max197_set_unipolarity(data, channel);
152 	} else if (value == -half) {
153 		max197_set_bipolarity(data, channel);
154 		max197_set_half_range(data, channel);
155 	} else if (value == -full) {
156 		max197_set_bipolarity(data, channel);
157 		max197_set_full_range(data, channel);
158 	} else if (value == half) {
159 		/* We can deduce only the range */
160 		max197_set_half_range(data, channel);
161 	} else if (value == full) {
162 		/* We can deduce only the range */
163 		max197_set_full_range(data, channel);
164 	}
165 
166 	mutex_unlock(&data->lock);
167 
168 	return count;
169 }
170 
171 /* Function called on read access on in{0,1,2,3,4,5,6,7}_input */
172 static ssize_t max197_show_input(struct device *dev,
173 				 struct device_attribute *devattr,
174 				 char *buf)
175 {
176 	struct max197_data *data = dev_get_drvdata(dev);
177 	struct sensor_device_attribute *attr = to_sensor_dev_attr(devattr);
178 	int channel = attr->index;
179 	s32 value;
180 	int ret;
181 
182 	if (mutex_lock_interruptible(&data->lock))
183 		return -ERESTARTSYS;
184 
185 	ret = data->pdata->convert(data->ctrl_bytes[channel]);
186 	if (ret < 0) {
187 		dev_err(dev, "conversion failed\n");
188 		goto unlock;
189 	}
190 	value = ret;
191 
192 	/*
193 	 * Coefficient to apply on raw value.
194 	 * See Table 1. Full Scale and Zero Scale in the MAX197 datasheet.
195 	 */
196 	if (data->scale) {
197 		value *= MAX197_SCALE;
198 		if (max197_is_full_range(data, channel))
199 			value *= 2;
200 		value /= 10000;
201 	}
202 
203 	ret = sprintf(buf, "%d\n", value);
204 
205 unlock:
206 	mutex_unlock(&data->lock);
207 	return ret;
208 }
209 
210 static ssize_t max197_show_name(struct device *dev,
211 				struct device_attribute *attr, char *buf)
212 {
213 	struct platform_device *pdev = to_platform_device(dev);
214 	return sprintf(buf, "%s\n", pdev->name);
215 }
216 
217 #define MAX197_SENSOR_DEVICE_ATTR_CH(chan)				\
218 	static SENSOR_DEVICE_ATTR(in##chan##_input, S_IRUGO,		\
219 				  max197_show_input, NULL, chan);	\
220 	static SENSOR_DEVICE_ATTR_2(in##chan##_min, S_IRUGO | S_IWUSR,	\
221 				    max197_show_range,			\
222 				    max197_store_range,			\
223 				    true, chan);			\
224 	static SENSOR_DEVICE_ATTR_2(in##chan##_max, S_IRUGO | S_IWUSR,	\
225 				    max197_show_range,			\
226 				    max197_store_range,			\
227 				    false, chan)
228 
229 #define MAX197_SENSOR_DEV_ATTR_IN(chan)					\
230 	&sensor_dev_attr_in##chan##_input.dev_attr.attr,		\
231 	&sensor_dev_attr_in##chan##_max.dev_attr.attr,			\
232 	&sensor_dev_attr_in##chan##_min.dev_attr.attr
233 
234 static DEVICE_ATTR(name, S_IRUGO, max197_show_name, NULL);
235 
236 MAX197_SENSOR_DEVICE_ATTR_CH(0);
237 MAX197_SENSOR_DEVICE_ATTR_CH(1);
238 MAX197_SENSOR_DEVICE_ATTR_CH(2);
239 MAX197_SENSOR_DEVICE_ATTR_CH(3);
240 MAX197_SENSOR_DEVICE_ATTR_CH(4);
241 MAX197_SENSOR_DEVICE_ATTR_CH(5);
242 MAX197_SENSOR_DEVICE_ATTR_CH(6);
243 MAX197_SENSOR_DEVICE_ATTR_CH(7);
244 
245 static const struct attribute_group max197_sysfs_group = {
246 	.attrs = (struct attribute *[]) {
247 		&dev_attr_name.attr,
248 		MAX197_SENSOR_DEV_ATTR_IN(0),
249 		MAX197_SENSOR_DEV_ATTR_IN(1),
250 		MAX197_SENSOR_DEV_ATTR_IN(2),
251 		MAX197_SENSOR_DEV_ATTR_IN(3),
252 		MAX197_SENSOR_DEV_ATTR_IN(4),
253 		MAX197_SENSOR_DEV_ATTR_IN(5),
254 		MAX197_SENSOR_DEV_ATTR_IN(6),
255 		MAX197_SENSOR_DEV_ATTR_IN(7),
256 		NULL
257 	},
258 };
259 
260 static int max197_probe(struct platform_device *pdev)
261 {
262 	int ch, ret;
263 	struct max197_data *data;
264 	struct max197_platform_data *pdata = dev_get_platdata(&pdev->dev);
265 	enum max197_chips chip = platform_get_device_id(pdev)->driver_data;
266 
267 	if (pdata == NULL) {
268 		dev_err(&pdev->dev, "no platform data supplied\n");
269 		return -EINVAL;
270 	}
271 
272 	if (pdata->convert == NULL) {
273 		dev_err(&pdev->dev, "no convert function supplied\n");
274 		return -EINVAL;
275 	}
276 
277 	data = devm_kzalloc(&pdev->dev, sizeof(struct max197_data), GFP_KERNEL);
278 	if (!data)
279 		return -ENOMEM;
280 
281 	data->pdata = pdata;
282 	mutex_init(&data->lock);
283 
284 	if (chip == max197) {
285 		data->limit = MAX197_LIMIT;
286 		data->scale = true;
287 	} else {
288 		data->limit = MAX199_LIMIT;
289 		data->scale = false;
290 	}
291 
292 	for (ch = 0; ch < MAX197_NUM_CH; ch++)
293 		data->ctrl_bytes[ch] = (u8) ch;
294 
295 	platform_set_drvdata(pdev, data);
296 
297 	ret = sysfs_create_group(&pdev->dev.kobj, &max197_sysfs_group);
298 	if (ret) {
299 		dev_err(&pdev->dev, "sysfs create group failed\n");
300 		return ret;
301 	}
302 
303 	data->hwmon_dev = hwmon_device_register(&pdev->dev);
304 	if (IS_ERR(data->hwmon_dev)) {
305 		ret = PTR_ERR(data->hwmon_dev);
306 		dev_err(&pdev->dev, "hwmon device register failed\n");
307 		goto error;
308 	}
309 
310 	return 0;
311 
312 error:
313 	sysfs_remove_group(&pdev->dev.kobj, &max197_sysfs_group);
314 	return ret;
315 }
316 
317 static int max197_remove(struct platform_device *pdev)
318 {
319 	struct max197_data *data = platform_get_drvdata(pdev);
320 
321 	hwmon_device_unregister(data->hwmon_dev);
322 	sysfs_remove_group(&pdev->dev.kobj, &max197_sysfs_group);
323 
324 	return 0;
325 }
326 
327 static const struct platform_device_id max197_device_ids[] = {
328 	{ "max197", max197 },
329 	{ "max199", max199 },
330 	{ }
331 };
332 MODULE_DEVICE_TABLE(platform, max197_device_ids);
333 
334 static struct platform_driver max197_driver = {
335 	.driver = {
336 		.name = "max197",
337 	},
338 	.probe = max197_probe,
339 	.remove = max197_remove,
340 	.id_table = max197_device_ids,
341 };
342 module_platform_driver(max197_driver);
343 
344 MODULE_LICENSE("GPL");
345 MODULE_AUTHOR("Savoir-faire Linux Inc. <kernel@savoirfairelinux.com>");
346 MODULE_DESCRIPTION("Maxim MAX197 A/D Converter driver");
347