1 /* 2 * mcp4725.c - Support for Microchip MCP4725 3 * 4 * Copyright (C) 2012 Peter Meerwald <pmeerw@pmeerw.net> 5 * 6 * Based on max517 by Roland Stigge <stigge@antcom.de> 7 * 8 * This file is subject to the terms and conditions of version 2 of 9 * the GNU General Public License. See the file COPYING in the main 10 * directory of this archive for more details. 11 * 12 * driver for the Microchip I2C 12-bit digital-to-analog converter (DAC) 13 * (7-bit I2C slave address 0x60, the three LSBs can be configured in 14 * hardware) 15 */ 16 17 #include <linux/module.h> 18 #include <linux/i2c.h> 19 #include <linux/err.h> 20 #include <linux/delay.h> 21 22 #include <linux/iio/iio.h> 23 #include <linux/iio/sysfs.h> 24 25 #include <linux/iio/dac/mcp4725.h> 26 27 #define MCP4725_DRV_NAME "mcp4725" 28 29 struct mcp4725_data { 30 struct i2c_client *client; 31 u16 vref_mv; 32 u16 dac_value; 33 bool powerdown; 34 unsigned powerdown_mode; 35 }; 36 37 static int mcp4725_suspend(struct device *dev) 38 { 39 struct mcp4725_data *data = iio_priv(i2c_get_clientdata( 40 to_i2c_client(dev))); 41 u8 outbuf[2]; 42 43 outbuf[0] = (data->powerdown_mode + 1) << 4; 44 outbuf[1] = 0; 45 data->powerdown = true; 46 47 return i2c_master_send(data->client, outbuf, 2); 48 } 49 50 static int mcp4725_resume(struct device *dev) 51 { 52 struct mcp4725_data *data = iio_priv(i2c_get_clientdata( 53 to_i2c_client(dev))); 54 u8 outbuf[2]; 55 56 /* restore previous DAC value */ 57 outbuf[0] = (data->dac_value >> 8) & 0xf; 58 outbuf[1] = data->dac_value & 0xff; 59 data->powerdown = false; 60 61 return i2c_master_send(data->client, outbuf, 2); 62 } 63 64 #ifdef CONFIG_PM_SLEEP 65 static SIMPLE_DEV_PM_OPS(mcp4725_pm_ops, mcp4725_suspend, mcp4725_resume); 66 #define MCP4725_PM_OPS (&mcp4725_pm_ops) 67 #else 68 #define MCP4725_PM_OPS NULL 69 #endif 70 71 static ssize_t mcp4725_store_eeprom(struct device *dev, 72 struct device_attribute *attr, const char *buf, size_t len) 73 { 74 struct iio_dev *indio_dev = dev_to_iio_dev(dev); 75 struct mcp4725_data *data = iio_priv(indio_dev); 76 int tries = 20; 77 u8 inoutbuf[3]; 78 bool state; 79 int ret; 80 81 ret = strtobool(buf, &state); 82 if (ret < 0) 83 return ret; 84 85 if (!state) 86 return 0; 87 88 inoutbuf[0] = 0x60; /* write EEPROM */ 89 inoutbuf[1] = data->dac_value >> 4; 90 inoutbuf[2] = (data->dac_value & 0xf) << 4; 91 92 ret = i2c_master_send(data->client, inoutbuf, 3); 93 if (ret < 0) 94 return ret; 95 else if (ret != 3) 96 return -EIO; 97 98 /* wait for write complete, takes up to 50ms */ 99 while (tries--) { 100 msleep(20); 101 ret = i2c_master_recv(data->client, inoutbuf, 3); 102 if (ret < 0) 103 return ret; 104 else if (ret != 3) 105 return -EIO; 106 107 if (inoutbuf[0] & 0x80) 108 break; 109 } 110 111 if (tries < 0) { 112 dev_err(&data->client->dev, 113 "mcp4725_store_eeprom() failed, incomplete\n"); 114 return -EIO; 115 } 116 117 return len; 118 } 119 120 static IIO_DEVICE_ATTR(store_eeprom, S_IWUSR, NULL, mcp4725_store_eeprom, 0); 121 122 static struct attribute *mcp4725_attributes[] = { 123 &iio_dev_attr_store_eeprom.dev_attr.attr, 124 NULL, 125 }; 126 127 static const struct attribute_group mcp4725_attribute_group = { 128 .attrs = mcp4725_attributes, 129 }; 130 131 static const char * const mcp4725_powerdown_modes[] = { 132 "1kohm_to_gnd", 133 "100kohm_to_gnd", 134 "500kohm_to_gnd" 135 }; 136 137 static int mcp4725_get_powerdown_mode(struct iio_dev *indio_dev, 138 const struct iio_chan_spec *chan) 139 { 140 struct mcp4725_data *data = iio_priv(indio_dev); 141 142 return data->powerdown_mode; 143 } 144 145 static int mcp4725_set_powerdown_mode(struct iio_dev *indio_dev, 146 const struct iio_chan_spec *chan, unsigned mode) 147 { 148 struct mcp4725_data *data = iio_priv(indio_dev); 149 150 data->powerdown_mode = mode; 151 152 return 0; 153 } 154 155 static ssize_t mcp4725_read_powerdown(struct iio_dev *indio_dev, 156 uintptr_t private, const struct iio_chan_spec *chan, char *buf) 157 { 158 struct mcp4725_data *data = iio_priv(indio_dev); 159 160 return sprintf(buf, "%d\n", data->powerdown); 161 } 162 163 static ssize_t mcp4725_write_powerdown(struct iio_dev *indio_dev, 164 uintptr_t private, const struct iio_chan_spec *chan, 165 const char *buf, size_t len) 166 { 167 struct mcp4725_data *data = iio_priv(indio_dev); 168 bool state; 169 int ret; 170 171 ret = strtobool(buf, &state); 172 if (ret) 173 return ret; 174 175 if (state) 176 ret = mcp4725_suspend(&data->client->dev); 177 else 178 ret = mcp4725_resume(&data->client->dev); 179 if (ret < 0) 180 return ret; 181 182 return len; 183 } 184 185 static const struct iio_enum mcp4725_powerdown_mode_enum = { 186 .items = mcp4725_powerdown_modes, 187 .num_items = ARRAY_SIZE(mcp4725_powerdown_modes), 188 .get = mcp4725_get_powerdown_mode, 189 .set = mcp4725_set_powerdown_mode, 190 }; 191 192 static const struct iio_chan_spec_ext_info mcp4725_ext_info[] = { 193 { 194 .name = "powerdown", 195 .read = mcp4725_read_powerdown, 196 .write = mcp4725_write_powerdown, 197 .shared = IIO_SEPARATE, 198 }, 199 IIO_ENUM("powerdown_mode", IIO_SEPARATE, &mcp4725_powerdown_mode_enum), 200 IIO_ENUM_AVAILABLE("powerdown_mode", &mcp4725_powerdown_mode_enum), 201 { }, 202 }; 203 204 static const struct iio_chan_spec mcp4725_channel = { 205 .type = IIO_VOLTAGE, 206 .indexed = 1, 207 .output = 1, 208 .channel = 0, 209 .info_mask_separate = BIT(IIO_CHAN_INFO_RAW), 210 .info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE), 211 .ext_info = mcp4725_ext_info, 212 }; 213 214 static int mcp4725_set_value(struct iio_dev *indio_dev, int val) 215 { 216 struct mcp4725_data *data = iio_priv(indio_dev); 217 u8 outbuf[2]; 218 int ret; 219 220 if (val >= (1 << 12) || val < 0) 221 return -EINVAL; 222 223 outbuf[0] = (val >> 8) & 0xf; 224 outbuf[1] = val & 0xff; 225 226 ret = i2c_master_send(data->client, outbuf, 2); 227 if (ret < 0) 228 return ret; 229 else if (ret != 2) 230 return -EIO; 231 else 232 return 0; 233 } 234 235 static int mcp4725_read_raw(struct iio_dev *indio_dev, 236 struct iio_chan_spec const *chan, 237 int *val, int *val2, long mask) 238 { 239 struct mcp4725_data *data = iio_priv(indio_dev); 240 241 switch (mask) { 242 case IIO_CHAN_INFO_RAW: 243 *val = data->dac_value; 244 return IIO_VAL_INT; 245 case IIO_CHAN_INFO_SCALE: 246 *val = data->vref_mv; 247 *val2 = 12; 248 return IIO_VAL_FRACTIONAL_LOG2; 249 } 250 return -EINVAL; 251 } 252 253 static int mcp4725_write_raw(struct iio_dev *indio_dev, 254 struct iio_chan_spec const *chan, 255 int val, int val2, long mask) 256 { 257 struct mcp4725_data *data = iio_priv(indio_dev); 258 int ret; 259 260 switch (mask) { 261 case IIO_CHAN_INFO_RAW: 262 ret = mcp4725_set_value(indio_dev, val); 263 data->dac_value = val; 264 break; 265 default: 266 ret = -EINVAL; 267 break; 268 } 269 270 return ret; 271 } 272 273 static const struct iio_info mcp4725_info = { 274 .read_raw = mcp4725_read_raw, 275 .write_raw = mcp4725_write_raw, 276 .attrs = &mcp4725_attribute_group, 277 .driver_module = THIS_MODULE, 278 }; 279 280 static int mcp4725_probe(struct i2c_client *client, 281 const struct i2c_device_id *id) 282 { 283 struct mcp4725_data *data; 284 struct iio_dev *indio_dev; 285 struct mcp4725_platform_data *platform_data = client->dev.platform_data; 286 u8 inbuf[3]; 287 u8 pd; 288 int err; 289 290 if (!platform_data || !platform_data->vref_mv) { 291 dev_err(&client->dev, "invalid platform data"); 292 return -EINVAL; 293 } 294 295 indio_dev = devm_iio_device_alloc(&client->dev, sizeof(*data)); 296 if (indio_dev == NULL) 297 return -ENOMEM; 298 data = iio_priv(indio_dev); 299 i2c_set_clientdata(client, indio_dev); 300 data->client = client; 301 302 indio_dev->dev.parent = &client->dev; 303 indio_dev->name = id->name; 304 indio_dev->info = &mcp4725_info; 305 indio_dev->channels = &mcp4725_channel; 306 indio_dev->num_channels = 1; 307 indio_dev->modes = INDIO_DIRECT_MODE; 308 309 data->vref_mv = platform_data->vref_mv; 310 311 /* read current DAC value */ 312 err = i2c_master_recv(client, inbuf, 3); 313 if (err < 0) { 314 dev_err(&client->dev, "failed to read DAC value"); 315 return err; 316 } 317 pd = (inbuf[0] >> 1) & 0x3; 318 data->powerdown = pd > 0 ? true : false; 319 data->powerdown_mode = pd ? pd-1 : 2; /* 500kohm_to_gnd */ 320 data->dac_value = (inbuf[1] << 4) | (inbuf[2] >> 4); 321 322 return iio_device_register(indio_dev); 323 } 324 325 static int mcp4725_remove(struct i2c_client *client) 326 { 327 iio_device_unregister(i2c_get_clientdata(client)); 328 return 0; 329 } 330 331 static const struct i2c_device_id mcp4725_id[] = { 332 { "mcp4725", 0 }, 333 { } 334 }; 335 MODULE_DEVICE_TABLE(i2c, mcp4725_id); 336 337 static struct i2c_driver mcp4725_driver = { 338 .driver = { 339 .name = MCP4725_DRV_NAME, 340 .pm = MCP4725_PM_OPS, 341 }, 342 .probe = mcp4725_probe, 343 .remove = mcp4725_remove, 344 .id_table = mcp4725_id, 345 }; 346 module_i2c_driver(mcp4725_driver); 347 348 MODULE_AUTHOR("Peter Meerwald <pmeerw@pmeerw.net>"); 349 MODULE_DESCRIPTION("MCP4725 12-bit DAC"); 350 MODULE_LICENSE("GPL"); 351