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Linux/drivers/hwmon/max197.c

  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 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                 .owner = THIS_MODULE,
338         },
339         .probe = max197_probe,
340         .remove = max197_remove,
341         .id_table = max197_device_ids,
342 };
343 module_platform_driver(max197_driver);
344 
345 MODULE_LICENSE("GPL");
346 MODULE_AUTHOR("Savoir-faire Linux Inc. <kernel@savoirfairelinux.com>");
347 MODULE_DESCRIPTION("Maxim MAX197 A/D Converter driver");
348 

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