1 /* 2 * ltc2497.c - Driver for Analog Devices/Linear Technology LTC2497 ADC 3 * 4 * Copyright (C) 2017 Analog Devices Inc. 5 * 6 * Licensed under the GPL-2. 7 * 8 * Datasheet: http://cds.linear.com/docs/en/datasheet/2497fd.pdf 9 */ 10 11 #include <linux/delay.h> 12 #include <linux/i2c.h> 13 #include <linux/iio/iio.h> 14 #include <linux/iio/driver.h> 15 #include <linux/iio/sysfs.h> 16 #include <linux/module.h> 17 #include <linux/of.h> 18 #include <linux/regulator/consumer.h> 19 20 #define LTC2497_ENABLE 0xA0 21 #define LTC2497_SGL BIT(4) 22 #define LTC2497_DIFF 0 23 #define LTC2497_SIGN BIT(3) 24 #define LTC2497_CONFIG_DEFAULT LTC2497_ENABLE 25 #define LTC2497_CONVERSION_TIME_MS 150ULL 26 27 struct ltc2497_st { 28 struct i2c_client *client; 29 struct regulator *ref; 30 ktime_t time_prev; 31 u8 addr_prev; 32 /* 33 * DMA (thus cache coherency maintenance) requires the 34 * transfer buffers to live in their own cache lines. 35 */ 36 __be32 buf ____cacheline_aligned; 37 }; 38 39 static int ltc2497_wait_conv(struct ltc2497_st *st) 40 { 41 s64 time_elapsed; 42 43 time_elapsed = ktime_ms_delta(ktime_get(), st->time_prev); 44 45 if (time_elapsed < LTC2497_CONVERSION_TIME_MS) { 46 /* delay if conversion time not passed 47 * since last read or write 48 */ 49 if (msleep_interruptible( 50 LTC2497_CONVERSION_TIME_MS - time_elapsed)) 51 return -ERESTARTSYS; 52 53 return 0; 54 } 55 56 if (time_elapsed - LTC2497_CONVERSION_TIME_MS <= 0) { 57 /* We're in automatic mode - 58 * so the last reading is stil not outdated 59 */ 60 return 0; 61 } 62 63 return 1; 64 } 65 66 static int ltc2497_read(struct ltc2497_st *st, u8 address, int *val) 67 { 68 struct i2c_client *client = st->client; 69 int ret; 70 71 ret = ltc2497_wait_conv(st); 72 if (ret < 0) 73 return ret; 74 75 if (ret || st->addr_prev != address) { 76 ret = i2c_smbus_write_byte(st->client, 77 LTC2497_ENABLE | address); 78 if (ret < 0) 79 return ret; 80 st->addr_prev = address; 81 if (msleep_interruptible(LTC2497_CONVERSION_TIME_MS)) 82 return -ERESTARTSYS; 83 } 84 ret = i2c_master_recv(client, (char *)&st->buf, 3); 85 if (ret < 0) { 86 dev_err(&client->dev, "i2c_master_recv failed\n"); 87 return ret; 88 } 89 st->time_prev = ktime_get(); 90 91 /* convert and shift the result, 92 * and finally convert from offset binary to signed integer 93 */ 94 *val = (be32_to_cpu(st->buf) >> 14) - (1 << 17); 95 96 return ret; 97 } 98 99 static int ltc2497_read_raw(struct iio_dev *indio_dev, 100 struct iio_chan_spec const *chan, 101 int *val, int *val2, long mask) 102 { 103 struct ltc2497_st *st = iio_priv(indio_dev); 104 int ret; 105 106 switch (mask) { 107 case IIO_CHAN_INFO_RAW: 108 mutex_lock(&indio_dev->mlock); 109 ret = ltc2497_read(st, chan->address, val); 110 mutex_unlock(&indio_dev->mlock); 111 if (ret < 0) 112 return ret; 113 114 return IIO_VAL_INT; 115 116 case IIO_CHAN_INFO_SCALE: 117 ret = regulator_get_voltage(st->ref); 118 if (ret < 0) 119 return ret; 120 121 *val = ret / 1000; 122 *val2 = 17; 123 124 return IIO_VAL_FRACTIONAL_LOG2; 125 126 default: 127 return -EINVAL; 128 } 129 } 130 131 #define LTC2497_CHAN(_chan, _addr, _ds_name) { \ 132 .type = IIO_VOLTAGE, \ 133 .indexed = 1, \ 134 .channel = (_chan), \ 135 .address = (_addr | (_chan / 2) | ((_chan & 1) ? LTC2497_SIGN : 0)), \ 136 .info_mask_separate = BIT(IIO_CHAN_INFO_RAW), \ 137 .info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE), \ 138 .datasheet_name = (_ds_name), \ 139 } 140 141 #define LTC2497_CHAN_DIFF(_chan, _addr) { \ 142 .type = IIO_VOLTAGE, \ 143 .indexed = 1, \ 144 .channel = (_chan) * 2 + ((_addr) & LTC2497_SIGN ? 1 : 0), \ 145 .channel2 = (_chan) * 2 + ((_addr) & LTC2497_SIGN ? 0 : 1),\ 146 .address = (_addr | _chan), \ 147 .info_mask_separate = BIT(IIO_CHAN_INFO_RAW), \ 148 .info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE), \ 149 .differential = 1, \ 150 } 151 152 static const struct iio_chan_spec ltc2497_channel[] = { 153 LTC2497_CHAN(0, LTC2497_SGL, "CH0"), 154 LTC2497_CHAN(1, LTC2497_SGL, "CH1"), 155 LTC2497_CHAN(2, LTC2497_SGL, "CH2"), 156 LTC2497_CHAN(3, LTC2497_SGL, "CH3"), 157 LTC2497_CHAN(4, LTC2497_SGL, "CH4"), 158 LTC2497_CHAN(5, LTC2497_SGL, "CH5"), 159 LTC2497_CHAN(6, LTC2497_SGL, "CH6"), 160 LTC2497_CHAN(7, LTC2497_SGL, "CH7"), 161 LTC2497_CHAN(8, LTC2497_SGL, "CH8"), 162 LTC2497_CHAN(9, LTC2497_SGL, "CH9"), 163 LTC2497_CHAN(10, LTC2497_SGL, "CH10"), 164 LTC2497_CHAN(11, LTC2497_SGL, "CH11"), 165 LTC2497_CHAN(12, LTC2497_SGL, "CH12"), 166 LTC2497_CHAN(13, LTC2497_SGL, "CH13"), 167 LTC2497_CHAN(14, LTC2497_SGL, "CH14"), 168 LTC2497_CHAN(15, LTC2497_SGL, "CH15"), 169 LTC2497_CHAN_DIFF(0, LTC2497_DIFF), 170 LTC2497_CHAN_DIFF(1, LTC2497_DIFF), 171 LTC2497_CHAN_DIFF(2, LTC2497_DIFF), 172 LTC2497_CHAN_DIFF(3, LTC2497_DIFF), 173 LTC2497_CHAN_DIFF(4, LTC2497_DIFF), 174 LTC2497_CHAN_DIFF(5, LTC2497_DIFF), 175 LTC2497_CHAN_DIFF(6, LTC2497_DIFF), 176 LTC2497_CHAN_DIFF(7, LTC2497_DIFF), 177 LTC2497_CHAN_DIFF(0, LTC2497_DIFF | LTC2497_SIGN), 178 LTC2497_CHAN_DIFF(1, LTC2497_DIFF | LTC2497_SIGN), 179 LTC2497_CHAN_DIFF(2, LTC2497_DIFF | LTC2497_SIGN), 180 LTC2497_CHAN_DIFF(3, LTC2497_DIFF | LTC2497_SIGN), 181 LTC2497_CHAN_DIFF(4, LTC2497_DIFF | LTC2497_SIGN), 182 LTC2497_CHAN_DIFF(5, LTC2497_DIFF | LTC2497_SIGN), 183 LTC2497_CHAN_DIFF(6, LTC2497_DIFF | LTC2497_SIGN), 184 LTC2497_CHAN_DIFF(7, LTC2497_DIFF | LTC2497_SIGN), 185 }; 186 187 static const struct iio_info ltc2497_info = { 188 .read_raw = ltc2497_read_raw, 189 .driver_module = THIS_MODULE, 190 }; 191 192 static int ltc2497_probe(struct i2c_client *client, 193 const struct i2c_device_id *id) 194 { 195 struct iio_dev *indio_dev; 196 struct ltc2497_st *st; 197 struct iio_map *plat_data; 198 int ret; 199 200 if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C | 201 I2C_FUNC_SMBUS_WRITE_BYTE)) 202 return -EOPNOTSUPP; 203 204 indio_dev = devm_iio_device_alloc(&client->dev, sizeof(*st)); 205 if (!indio_dev) 206 return -ENOMEM; 207 208 st = iio_priv(indio_dev); 209 i2c_set_clientdata(client, indio_dev); 210 st->client = client; 211 212 indio_dev->dev.parent = &client->dev; 213 indio_dev->name = id->name; 214 indio_dev->info = <c2497_info; 215 indio_dev->modes = INDIO_DIRECT_MODE; 216 indio_dev->channels = ltc2497_channel; 217 indio_dev->num_channels = ARRAY_SIZE(ltc2497_channel); 218 219 st->ref = devm_regulator_get(&client->dev, "vref"); 220 if (IS_ERR(st->ref)) 221 return PTR_ERR(st->ref); 222 223 ret = regulator_enable(st->ref); 224 if (ret < 0) 225 return ret; 226 227 if (client->dev.platform_data) { 228 plat_data = ((struct iio_map *)client->dev.platform_data); 229 ret = iio_map_array_register(indio_dev, plat_data); 230 if (ret) { 231 dev_err(&indio_dev->dev, "iio map err: %d\n", ret); 232 goto err_regulator_disable; 233 } 234 } 235 236 ret = i2c_smbus_write_byte(st->client, LTC2497_CONFIG_DEFAULT); 237 if (ret < 0) 238 goto err_array_unregister; 239 240 st->addr_prev = LTC2497_CONFIG_DEFAULT; 241 st->time_prev = ktime_get(); 242 243 ret = iio_device_register(indio_dev); 244 if (ret < 0) 245 goto err_array_unregister; 246 247 return 0; 248 249 err_array_unregister: 250 iio_map_array_unregister(indio_dev); 251 252 err_regulator_disable: 253 regulator_disable(st->ref); 254 255 return ret; 256 } 257 258 static int ltc2497_remove(struct i2c_client *client) 259 { 260 struct iio_dev *indio_dev = i2c_get_clientdata(client); 261 struct ltc2497_st *st = iio_priv(indio_dev); 262 263 iio_map_array_unregister(indio_dev); 264 iio_device_unregister(indio_dev); 265 regulator_disable(st->ref); 266 267 return 0; 268 } 269 270 static const struct i2c_device_id ltc2497_id[] = { 271 { "ltc2497", 0 }, 272 { } 273 }; 274 MODULE_DEVICE_TABLE(i2c, ltc2497_id); 275 276 static const struct of_device_id ltc2497_of_match[] = { 277 { .compatible = "lltc,ltc2497", }, 278 {}, 279 }; 280 MODULE_DEVICE_TABLE(of, ltc2497_of_match); 281 282 static struct i2c_driver ltc2497_driver = { 283 .driver = { 284 .name = "ltc2497", 285 .of_match_table = of_match_ptr(ltc2497_of_match), 286 }, 287 .probe = ltc2497_probe, 288 .remove = ltc2497_remove, 289 .id_table = ltc2497_id, 290 }; 291 module_i2c_driver(ltc2497_driver); 292 293 MODULE_AUTHOR("Michael Hennerich <michael.hennerich@analog.com>"); 294 MODULE_DESCRIPTION("Linear Technology LTC2497 ADC driver"); 295 MODULE_LICENSE("GPL v2"); 296