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