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 */
39enum 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 */
50struct 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
59static inline void max197_set_unipolarity(struct max197_data *data, int channel)
60{
61	data->ctrl_bytes[channel] &= ~MAX197_BIP;
62}
63
64static inline void max197_set_bipolarity(struct max197_data *data, int channel)
65{
66	data->ctrl_bytes[channel] |= MAX197_BIP;
67}
68
69static inline void max197_set_half_range(struct max197_data *data, int channel)
70{
71	data->ctrl_bytes[channel] &= ~MAX197_RNG;
72}
73
74static inline void max197_set_full_range(struct max197_data *data, int channel)
75{
76	data->ctrl_bytes[channel] |= MAX197_RNG;
77}
78
79static inline bool max197_is_bipolar(struct max197_data *data, int channel)
80{
81	return data->ctrl_bytes[channel] & MAX197_BIP;
82}
83
84static 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} */
90static 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} */
117static 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 */
172static 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
205unlock:
206	mutex_unlock(&data->lock);
207	return ret;
208}
209
210static 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
234static DEVICE_ATTR(name, S_IRUGO, max197_show_name, NULL);
235
236MAX197_SENSOR_DEVICE_ATTR_CH(0);
237MAX197_SENSOR_DEVICE_ATTR_CH(1);
238MAX197_SENSOR_DEVICE_ATTR_CH(2);
239MAX197_SENSOR_DEVICE_ATTR_CH(3);
240MAX197_SENSOR_DEVICE_ATTR_CH(4);
241MAX197_SENSOR_DEVICE_ATTR_CH(5);
242MAX197_SENSOR_DEVICE_ATTR_CH(6);
243MAX197_SENSOR_DEVICE_ATTR_CH(7);
244
245static 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
260static 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
312error:
313	sysfs_remove_group(&pdev->dev.kobj, &max197_sysfs_group);
314	return ret;
315}
316
317static 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
327static struct platform_device_id max197_device_ids[] = {
328	{ "max197", max197 },
329	{ "max199", max199 },
330	{ }
331};
332MODULE_DEVICE_TABLE(platform, max197_device_ids);
333
334static 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};
342module_platform_driver(max197_driver);
343
344MODULE_LICENSE("GPL");
345MODULE_AUTHOR("Savoir-faire Linux Inc. <kernel@savoirfairelinux.com>");
346MODULE_DESCRIPTION("Maxim MAX197 A/D Converter driver");
347