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/init.h> 19 #include <linux/i2c.h> 20 #include <linux/err.h> 21 #include <linux/delay.h> 22 23 #include <linux/iio/iio.h> 24 #include <linux/iio/sysfs.h> 25 26 #include <linux/iio/dac/mcp4725.h> 27 28 #define MCP4725_DRV_NAME "mcp4725" 29 30 struct mcp4725_data { 31 struct i2c_client *client; 32 u16 vref_mv; 33 u16 dac_value; 34 bool powerdown; 35 unsigned powerdown_mode; 36 }; 37 38 static int mcp4725_suspend(struct device *dev) 39 { 40 struct iio_dev *indio_dev = dev_to_iio_dev(dev); 41 struct mcp4725_data *data = iio_priv(indio_dev); 42 u8 outbuf[2]; 43 44 outbuf[0] = (data->powerdown_mode + 1) << 4; 45 outbuf[1] = 0; 46 data->powerdown = true; 47 48 return i2c_master_send(to_i2c_client(dev), outbuf, 2); 49 } 50 51 static int mcp4725_resume(struct device *dev) 52 { 53 struct iio_dev *indio_dev = dev_to_iio_dev(dev); 54 struct mcp4725_data *data = iio_priv(indio_dev); 55 u8 outbuf[2]; 56 57 /* restore previous DAC value */ 58 outbuf[0] = (data->dac_value >> 8) & 0xf; 59 outbuf[1] = data->dac_value & 0xff; 60 data->powerdown = false; 61 62 return i2c_master_send(to_i2c_client(dev), outbuf, 2); 63 } 64 65 #ifdef CONFIG_PM_SLEEP 66 static SIMPLE_DEV_PM_OPS(mcp4725_pm_ops, mcp4725_suspend, mcp4725_resume); 67 #define MCP4725_PM_OPS (&mcp4725_pm_ops) 68 #else 69 #define MCP4725_PM_OPS NULL 70 #endif 71 72 static int mcp4725_store_eeprom(struct device *dev, 73 struct device_attribute *attr, const char *buf, size_t len) 74 { 75 struct iio_dev *indio_dev = dev_to_iio_dev(dev); 76 struct mcp4725_data *data = iio_priv(indio_dev); 77 int tries = 20; 78 u8 inoutbuf[3]; 79 bool state; 80 int ret; 81 82 ret = strtobool(buf, &state); 83 if (ret < 0) 84 return ret; 85 86 if (!state) 87 return 0; 88 89 inoutbuf[0] = 0x60; /* write EEPROM */ 90 inoutbuf[1] = data->dac_value >> 4; 91 inoutbuf[2] = (data->dac_value & 0xf) << 4; 92 93 ret = i2c_master_send(data->client, inoutbuf, 3); 94 if (ret < 0) 95 return ret; 96 else if (ret != 3) 97 return -EIO; 98 99 /* wait for write complete, takes up to 50ms */ 100 while (tries--) { 101 msleep(20); 102 ret = i2c_master_recv(data->client, inoutbuf, 3); 103 if (ret < 0) 104 return ret; 105 else if (ret != 3) 106 return -EIO; 107 108 if (inoutbuf[0] & 0x80) 109 break; 110 } 111 112 if (tries < 0) { 113 dev_err(&data->client->dev, 114 "mcp4725_store_eeprom() failed, incomplete\n"); 115 return -EIO; 116 } 117 118 return len; 119 } 120 121 static IIO_DEVICE_ATTR(store_eeprom, S_IWUSR, NULL, mcp4725_store_eeprom, 0); 122 123 static struct attribute *mcp4725_attributes[] = { 124 &iio_dev_attr_store_eeprom.dev_attr.attr, 125 NULL, 126 }; 127 128 static const struct attribute_group mcp4725_attribute_group = { 129 .attrs = mcp4725_attributes, 130 }; 131 132 static const char * const mcp4725_powerdown_modes[] = { 133 "1kohm_to_gnd", 134 "100kohm_to_gnd", 135 "500kohm_to_gnd" 136 }; 137 138 static int mcp4725_get_powerdown_mode(struct iio_dev *indio_dev, 139 const struct iio_chan_spec *chan) 140 { 141 struct mcp4725_data *data = iio_priv(indio_dev); 142 143 return data->powerdown_mode; 144 } 145 146 static int mcp4725_set_powerdown_mode(struct iio_dev *indio_dev, 147 const struct iio_chan_spec *chan, unsigned mode) 148 { 149 struct mcp4725_data *data = iio_priv(indio_dev); 150 151 data->powerdown_mode = mode; 152 153 return 0; 154 } 155 156 static ssize_t mcp4725_read_powerdown(struct iio_dev *indio_dev, 157 uintptr_t private, const struct iio_chan_spec *chan, char *buf) 158 { 159 struct mcp4725_data *data = iio_priv(indio_dev); 160 161 return sprintf(buf, "%d\n", data->powerdown); 162 } 163 164 static ssize_t mcp4725_write_powerdown(struct iio_dev *indio_dev, 165 uintptr_t private, const struct iio_chan_spec *chan, 166 const char *buf, size_t len) 167 { 168 struct mcp4725_data *data = iio_priv(indio_dev); 169 bool state; 170 int ret; 171 172 ret = strtobool(buf, &state); 173 if (ret) 174 return ret; 175 176 if (state) 177 ret = mcp4725_suspend(&data->client->dev); 178 else 179 ret = mcp4725_resume(&data->client->dev); 180 if (ret < 0) 181 return ret; 182 183 return len; 184 } 185 186 static const struct iio_enum mcp4725_powerdown_mode_enum = { 187 .items = mcp4725_powerdown_modes, 188 .num_items = ARRAY_SIZE(mcp4725_powerdown_modes), 189 .get = mcp4725_get_powerdown_mode, 190 .set = mcp4725_set_powerdown_mode, 191 }; 192 193 static const struct iio_chan_spec_ext_info mcp4725_ext_info[] = { 194 { 195 .name = "powerdown", 196 .read = mcp4725_read_powerdown, 197 .write = mcp4725_write_powerdown, 198 }, 199 IIO_ENUM("powerdown_mode", false, &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 .scan_type = IIO_ST('u', 12, 16, 0), 212 .ext_info = mcp4725_ext_info, 213 }; 214 215 static int mcp4725_set_value(struct iio_dev *indio_dev, int val) 216 { 217 struct mcp4725_data *data = iio_priv(indio_dev); 218 u8 outbuf[2]; 219 int ret; 220 221 if (val >= (1 << 12) || val < 0) 222 return -EINVAL; 223 224 outbuf[0] = (val >> 8) & 0xf; 225 outbuf[1] = val & 0xff; 226 227 ret = i2c_master_send(data->client, outbuf, 2); 228 if (ret < 0) 229 return ret; 230 else if (ret != 2) 231 return -EIO; 232 else 233 return 0; 234 } 235 236 static int mcp4725_read_raw(struct iio_dev *indio_dev, 237 struct iio_chan_spec const *chan, 238 int *val, int *val2, long mask) 239 { 240 struct mcp4725_data *data = iio_priv(indio_dev); 241 unsigned long scale_uv; 242 243 switch (mask) { 244 case IIO_CHAN_INFO_RAW: 245 *val = data->dac_value; 246 return IIO_VAL_INT; 247 case IIO_CHAN_INFO_SCALE: 248 scale_uv = (data->vref_mv * 1000) >> 12; 249 *val = scale_uv / 1000000; 250 *val2 = scale_uv % 1000000; 251 return IIO_VAL_INT_PLUS_MICRO; 252 } 253 return -EINVAL; 254 } 255 256 static int mcp4725_write_raw(struct iio_dev *indio_dev, 257 struct iio_chan_spec const *chan, 258 int val, int val2, long mask) 259 { 260 struct mcp4725_data *data = iio_priv(indio_dev); 261 int ret; 262 263 switch (mask) { 264 case IIO_CHAN_INFO_RAW: 265 ret = mcp4725_set_value(indio_dev, val); 266 data->dac_value = val; 267 break; 268 default: 269 ret = -EINVAL; 270 break; 271 } 272 273 return ret; 274 } 275 276 static const struct iio_info mcp4725_info = { 277 .read_raw = mcp4725_read_raw, 278 .write_raw = mcp4725_write_raw, 279 .attrs = &mcp4725_attribute_group, 280 .driver_module = THIS_MODULE, 281 }; 282 283 static int mcp4725_probe(struct i2c_client *client, 284 const struct i2c_device_id *id) 285 { 286 struct mcp4725_data *data; 287 struct iio_dev *indio_dev; 288 struct mcp4725_platform_data *platform_data = client->dev.platform_data; 289 u8 inbuf[3]; 290 u8 pd; 291 int err; 292 293 if (!platform_data || !platform_data->vref_mv) { 294 dev_err(&client->dev, "invalid platform data"); 295 err = -EINVAL; 296 goto exit; 297 } 298 299 indio_dev = iio_device_alloc(sizeof(*data)); 300 if (indio_dev == NULL) { 301 err = -ENOMEM; 302 goto exit; 303 } 304 data = iio_priv(indio_dev); 305 i2c_set_clientdata(client, indio_dev); 306 data->client = client; 307 308 indio_dev->dev.parent = &client->dev; 309 indio_dev->info = &mcp4725_info; 310 indio_dev->channels = &mcp4725_channel; 311 indio_dev->num_channels = 1; 312 indio_dev->modes = INDIO_DIRECT_MODE; 313 314 data->vref_mv = platform_data->vref_mv; 315 316 /* read current DAC value */ 317 err = i2c_master_recv(client, inbuf, 3); 318 if (err < 0) { 319 dev_err(&client->dev, "failed to read DAC value"); 320 goto exit_free_device; 321 } 322 pd = (inbuf[0] >> 1) & 0x3; 323 data->powerdown = pd > 0 ? true : false; 324 data->powerdown_mode = pd ? pd-1 : 2; /* 500kohm_to_gnd */ 325 data->dac_value = (inbuf[1] << 4) | (inbuf[2] >> 4); 326 327 err = iio_device_register(indio_dev); 328 if (err) 329 goto exit_free_device; 330 331 dev_info(&client->dev, "MCP4725 DAC registered\n"); 332 333 return 0; 334 335 exit_free_device: 336 iio_device_free(indio_dev); 337 exit: 338 return err; 339 } 340 341 static int mcp4725_remove(struct i2c_client *client) 342 { 343 struct iio_dev *indio_dev = i2c_get_clientdata(client); 344 345 iio_device_unregister(indio_dev); 346 iio_device_free(indio_dev); 347 348 return 0; 349 } 350 351 static const struct i2c_device_id mcp4725_id[] = { 352 { "mcp4725", 0 }, 353 { } 354 }; 355 MODULE_DEVICE_TABLE(i2c, mcp4725_id); 356 357 static struct i2c_driver mcp4725_driver = { 358 .driver = { 359 .name = MCP4725_DRV_NAME, 360 .pm = MCP4725_PM_OPS, 361 }, 362 .probe = mcp4725_probe, 363 .remove = mcp4725_remove, 364 .id_table = mcp4725_id, 365 }; 366 module_i2c_driver(mcp4725_driver); 367 368 MODULE_AUTHOR("Peter Meerwald <pmeerw@pmeerw.net>"); 369 MODULE_DESCRIPTION("MCP4725 12-bit DAC"); 370 MODULE_LICENSE("GPL"); 371