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max517.c
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1 /*
2  * max517.c - Support for Maxim MAX517, MAX518 and MAX519
3  *
4  * Copyright (C) 2010, 2011 Roland Stigge <[email protected]>
5  *
6  * This program is free software; you can redistribute it and/or modify
7  * it under the terms of the GNU General Public License as published by
8  * the Free Software Foundation; either version 2 of the License, or
9  * (at your option) any later version.
10  *
11  * This program is distributed in the hope that it will be useful,
12  * but WITHOUT ANY WARRANTY; without even the implied warranty of
13  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
14  * GNU General Public License for more details.
15  *
16  * You should have received a copy of the GNU General Public License
17  * along with this program; if not, write to the Free Software
18  * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
19  */
20 
21 #include <linux/module.h>
22 #include <linux/init.h>
23 #include <linux/slab.h>
24 #include <linux/jiffies.h>
25 #include <linux/i2c.h>
26 #include <linux/err.h>
27 
28 #include <linux/iio/iio.h>
29 #include <linux/iio/sysfs.h>
30 #include <linux/iio/dac/max517.h>
31 
32 #define MAX517_DRV_NAME "max517"
33 
34 /* Commands */
35 #define COMMAND_CHANNEL0 0x00
36 #define COMMAND_CHANNEL1 0x01 /* for MAX518 and MAX519 */
37 #define COMMAND_PD 0x08 /* Power Down */
38 
43 };
44 
45 struct max517_data {
46  struct i2c_client *client;
47  unsigned short vref_mv[2];
48 };
49 
50 /*
51  * channel: bit 0: channel 1
52  * bit 1: channel 2
53  * (this way, it's possible to set both channels at once)
54  */
55 static int max517_set_value(struct iio_dev *indio_dev,
56  long val, int channel)
57 {
58  struct max517_data *data = iio_priv(indio_dev);
59  struct i2c_client *client = data->client;
60  u8 outbuf[2];
61  int res;
62 
63  if (val < 0 || val > 255)
64  return -EINVAL;
65 
66  outbuf[0] = channel;
67  outbuf[1] = val;
68 
69  res = i2c_master_send(client, outbuf, 2);
70  if (res < 0)
71  return res;
72  else if (res != 2)
73  return -EIO;
74  else
75  return 0;
76 }
77 
78 static int max517_read_raw(struct iio_dev *indio_dev,
79  struct iio_chan_spec const *chan,
80  int *val,
81  int *val2,
82  long m)
83 {
84  struct max517_data *data = iio_priv(indio_dev);
85  unsigned int scale_uv;
86 
87  switch (m) {
89  /* Corresponds to Vref / 2^(bits) */
90  scale_uv = (data->vref_mv[chan->channel] * 1000) >> 8;
91  *val = scale_uv / 1000000;
92  *val2 = scale_uv % 1000000;
94  default:
95  break;
96  }
97  return -EINVAL;
98 }
99 
100 static int max517_write_raw(struct iio_dev *indio_dev,
101  struct iio_chan_spec const *chan, int val, int val2, long mask)
102 {
103  int ret;
104 
105  switch (mask) {
106  case IIO_CHAN_INFO_RAW:
107  ret = max517_set_value(indio_dev, val, chan->channel);
108  break;
109  default:
110  ret = -EINVAL;
111  break;
112  }
113 
114  return ret;
115 }
116 
117 #ifdef CONFIG_PM_SLEEP
118 static int max517_suspend(struct device *dev)
119 {
120  u8 outbuf = COMMAND_PD;
121 
122  return i2c_master_send(to_i2c_client(dev), &outbuf, 1);
123 }
124 
125 static int max517_resume(struct device *dev)
126 {
127  u8 outbuf = 0;
128 
129  return i2c_master_send(to_i2c_client(dev), &outbuf, 1);
130 }
131 
132 static SIMPLE_DEV_PM_OPS(max517_pm_ops, max517_suspend, max517_resume);
133 #define MAX517_PM_OPS (&max517_pm_ops)
134 #else
135 #define MAX517_PM_OPS NULL
136 #endif
137 
138 static const struct iio_info max517_info = {
139  .read_raw = max517_read_raw,
140  .write_raw = max517_write_raw,
141  .driver_module = THIS_MODULE,
142 };
143 
144 #define MAX517_CHANNEL(chan) { \
145  .type = IIO_VOLTAGE, \
146  .indexed = 1, \
147  .output = 1, \
148  .channel = (chan), \
149  .info_mask = IIO_CHAN_INFO_RAW_SEPARATE_BIT | \
150  IIO_CHAN_INFO_SCALE_SEPARATE_BIT, \
151  .scan_type = IIO_ST('u', 8, 8, 0), \
152 }
153 
154 static const struct iio_chan_spec max517_channels[] = {
155  MAX517_CHANNEL(0),
156  MAX517_CHANNEL(1)
157 };
158 
159 static int __devinit max517_probe(struct i2c_client *client,
160  const struct i2c_device_id *id)
161 {
162  struct max517_data *data;
163  struct iio_dev *indio_dev;
164  struct max517_platform_data *platform_data = client->dev.platform_data;
165  int err;
166 
167  indio_dev = iio_device_alloc(sizeof(*data));
168  if (indio_dev == NULL) {
169  err = -ENOMEM;
170  goto exit;
171  }
172  data = iio_priv(indio_dev);
173  i2c_set_clientdata(client, indio_dev);
174  data->client = client;
175 
176  /* establish that the iio_dev is a child of the i2c device */
177  indio_dev->dev.parent = &client->dev;
178 
179  /* reduced channel set for MAX517 */
180  if (id->driver_data == ID_MAX517)
181  indio_dev->num_channels = 1;
182  else
183  indio_dev->num_channels = 2;
184  indio_dev->channels = max517_channels;
185  indio_dev->modes = INDIO_DIRECT_MODE;
186  indio_dev->info = &max517_info;
187 
188  /*
189  * Reference voltage on MAX518 and default is 5V, else take vref_mv
190  * from platform_data
191  */
192  if (id->driver_data == ID_MAX518 || !platform_data) {
193  data->vref_mv[0] = data->vref_mv[1] = 5000; /* mV */
194  } else {
195  data->vref_mv[0] = platform_data->vref_mv[0];
196  data->vref_mv[1] = platform_data->vref_mv[1];
197  }
198 
199  err = iio_device_register(indio_dev);
200  if (err)
201  goto exit_free_device;
202 
203  dev_info(&client->dev, "DAC registered\n");
204 
205  return 0;
206 
207 exit_free_device:
208  iio_device_free(indio_dev);
209 exit:
210  return err;
211 }
212 
213 static int __devexit max517_remove(struct i2c_client *client)
214 {
215  iio_device_unregister(i2c_get_clientdata(client));
216  iio_device_free(i2c_get_clientdata(client));
217 
218  return 0;
219 }
220 
221 static const struct i2c_device_id max517_id[] = {
222  { "max517", ID_MAX517 },
223  { "max518", ID_MAX518 },
224  { "max519", ID_MAX519 },
225  { }
226 };
227 MODULE_DEVICE_TABLE(i2c, max517_id);
228 
229 static struct i2c_driver max517_driver = {
230  .driver = {
231  .name = MAX517_DRV_NAME,
232  .pm = MAX517_PM_OPS,
233  },
234  .probe = max517_probe,
235  .remove = __devexit_p(max517_remove),
236  .id_table = max517_id,
237 };
238 module_i2c_driver(max517_driver);
239 
240 MODULE_AUTHOR("Roland Stigge <[email protected]>");
241 MODULE_DESCRIPTION("MAX517/MAX518/MAX519 8-bit DAC");
242 MODULE_LICENSE("GPL");