1 // SPDX-License-Identifier: GPL-2.0-only 2 /* 3 * ltc2497.c - Driver for Analog Devices/Linear Technology LTC2497 ADC 4 * 5 * Copyright (C) 2017 Analog Devices Inc. 6 * 7 * Datasheet: http://cds.linear.com/docs/en/datasheet/2497fd.pdf 8 */ 9 10 #include <linux/delay.h> 11 #include <linux/i2c.h> 12 #include <linux/iio/iio.h> 13 #include <linux/iio/driver.h> 14 #include <linux/iio/sysfs.h> 15 #include <linux/module.h> 16 #include <linux/of.h> 17 #include <linux/regulator/consumer.h> 18 19 #define LTC2497_ENABLE 0xA0 20 #define LTC2497_SGL BIT(4) 21 #define LTC2497_DIFF 0 22 #define LTC2497_SIGN BIT(3) 23 #define LTC2497_CONFIG_DEFAULT LTC2497_ENABLE 24 #define LTC2497_CONVERSION_TIME_MS 150ULL 25 26 struct ltc2497_st { 27 struct i2c_client *client; 28 struct regulator *ref; 29 ktime_t time_prev; 30 u8 addr_prev; 31 /* 32 * DMA (thus cache coherency maintenance) requires the 33 * transfer buffers to live in their own cache lines. 34 */ 35 __be32 buf ____cacheline_aligned; 36 }; 37 38 static int ltc2497_wait_conv(struct ltc2497_st *st) 39 { 40 s64 time_elapsed; 41 42 time_elapsed = ktime_ms_delta(ktime_get(), st->time_prev); 43 44 if (time_elapsed < LTC2497_CONVERSION_TIME_MS) { 45 /* delay if conversion time not passed 46 * since last read or write 47 */ 48 if (msleep_interruptible( 49 LTC2497_CONVERSION_TIME_MS - time_elapsed)) 50 return -ERESTARTSYS; 51 52 return 0; 53 } 54 55 if (time_elapsed - LTC2497_CONVERSION_TIME_MS <= 0) { 56 /* We're in automatic mode - 57 * so the last reading is stil not outdated 58 */ 59 return 0; 60 } 61 62 return 1; 63 } 64 65 static int ltc2497_read(struct ltc2497_st *st, u8 address, int *val) 66 { 67 struct i2c_client *client = st->client; 68 int ret; 69 70 ret = ltc2497_wait_conv(st); 71 if (ret < 0) 72 return ret; 73 74 if (ret || st->addr_prev != address) { 75 ret = i2c_smbus_write_byte(st->client, 76 LTC2497_ENABLE | address); 77 if (ret < 0) 78 return ret; 79 st->addr_prev = address; 80 if (msleep_interruptible(LTC2497_CONVERSION_TIME_MS)) 81 return -ERESTARTSYS; 82 } 83 ret = i2c_master_recv(client, (char *)&st->buf, 3); 84 if (ret < 0) { 85 dev_err(&client->dev, "i2c_master_recv failed\n"); 86 return ret; 87 } 88 st->time_prev = ktime_get(); 89 90 /* convert and shift the result, 91 * and finally convert from offset binary to signed integer 92 */ 93 *val = (be32_to_cpu(st->buf) >> 14) - (1 << 17); 94 95 return ret; 96 } 97 98 static int ltc2497_read_raw(struct iio_dev *indio_dev, 99 struct iio_chan_spec const *chan, 100 int *val, int *val2, long mask) 101 { 102 struct ltc2497_st *st = iio_priv(indio_dev); 103 int ret; 104 105 switch (mask) { 106 case IIO_CHAN_INFO_RAW: 107 mutex_lock(&indio_dev->mlock); 108 ret = ltc2497_read(st, chan->address, val); 109 mutex_unlock(&indio_dev->mlock); 110 if (ret < 0) 111 return ret; 112 113 return IIO_VAL_INT; 114 115 case IIO_CHAN_INFO_SCALE: 116 ret = regulator_get_voltage(st->ref); 117 if (ret < 0) 118 return ret; 119 120 *val = ret / 1000; 121 *val2 = 17; 122 123 return IIO_VAL_FRACTIONAL_LOG2; 124 125 default: 126 return -EINVAL; 127 } 128 } 129 130 #define LTC2497_CHAN(_chan, _addr, _ds_name) { \ 131 .type = IIO_VOLTAGE, \ 132 .indexed = 1, \ 133 .channel = (_chan), \ 134 .address = (_addr | (_chan / 2) | ((_chan & 1) ? LTC2497_SIGN : 0)), \ 135 .info_mask_separate = BIT(IIO_CHAN_INFO_RAW), \ 136 .info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE), \ 137 .datasheet_name = (_ds_name), \ 138 } 139 140 #define LTC2497_CHAN_DIFF(_chan, _addr) { \ 141 .type = IIO_VOLTAGE, \ 142 .indexed = 1, \ 143 .channel = (_chan) * 2 + ((_addr) & LTC2497_SIGN ? 1 : 0), \ 144 .channel2 = (_chan) * 2 + ((_addr) & LTC2497_SIGN ? 0 : 1),\ 145 .address = (_addr | _chan), \ 146 .info_mask_separate = BIT(IIO_CHAN_INFO_RAW), \ 147 .info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE), \ 148 .differential = 1, \ 149 } 150 151 static const struct iio_chan_spec ltc2497_channel[] = { 152 LTC2497_CHAN(0, LTC2497_SGL, "CH0"), 153 LTC2497_CHAN(1, LTC2497_SGL, "CH1"), 154 LTC2497_CHAN(2, LTC2497_SGL, "CH2"), 155 LTC2497_CHAN(3, LTC2497_SGL, "CH3"), 156 LTC2497_CHAN(4, LTC2497_SGL, "CH4"), 157 LTC2497_CHAN(5, LTC2497_SGL, "CH5"), 158 LTC2497_CHAN(6, LTC2497_SGL, "CH6"), 159 LTC2497_CHAN(7, LTC2497_SGL, "CH7"), 160 LTC2497_CHAN(8, LTC2497_SGL, "CH8"), 161 LTC2497_CHAN(9, LTC2497_SGL, "CH9"), 162 LTC2497_CHAN(10, LTC2497_SGL, "CH10"), 163 LTC2497_CHAN(11, LTC2497_SGL, "CH11"), 164 LTC2497_CHAN(12, LTC2497_SGL, "CH12"), 165 LTC2497_CHAN(13, LTC2497_SGL, "CH13"), 166 LTC2497_CHAN(14, LTC2497_SGL, "CH14"), 167 LTC2497_CHAN(15, LTC2497_SGL, "CH15"), 168 LTC2497_CHAN_DIFF(0, LTC2497_DIFF), 169 LTC2497_CHAN_DIFF(1, LTC2497_DIFF), 170 LTC2497_CHAN_DIFF(2, LTC2497_DIFF), 171 LTC2497_CHAN_DIFF(3, LTC2497_DIFF), 172 LTC2497_CHAN_DIFF(4, LTC2497_DIFF), 173 LTC2497_CHAN_DIFF(5, LTC2497_DIFF), 174 LTC2497_CHAN_DIFF(6, LTC2497_DIFF), 175 LTC2497_CHAN_DIFF(7, LTC2497_DIFF), 176 LTC2497_CHAN_DIFF(0, LTC2497_DIFF | LTC2497_SIGN), 177 LTC2497_CHAN_DIFF(1, LTC2497_DIFF | LTC2497_SIGN), 178 LTC2497_CHAN_DIFF(2, LTC2497_DIFF | LTC2497_SIGN), 179 LTC2497_CHAN_DIFF(3, LTC2497_DIFF | LTC2497_SIGN), 180 LTC2497_CHAN_DIFF(4, LTC2497_DIFF | LTC2497_SIGN), 181 LTC2497_CHAN_DIFF(5, LTC2497_DIFF | LTC2497_SIGN), 182 LTC2497_CHAN_DIFF(6, LTC2497_DIFF | LTC2497_SIGN), 183 LTC2497_CHAN_DIFF(7, LTC2497_DIFF | LTC2497_SIGN), 184 }; 185 186 static const struct iio_info ltc2497_info = { 187 .read_raw = ltc2497_read_raw, 188 }; 189 190 static int ltc2497_probe(struct i2c_client *client, 191 const struct i2c_device_id *id) 192 { 193 struct iio_dev *indio_dev; 194 struct ltc2497_st *st; 195 struct iio_map *plat_data; 196 int ret; 197 198 if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C | 199 I2C_FUNC_SMBUS_WRITE_BYTE)) 200 return -EOPNOTSUPP; 201 202 indio_dev = devm_iio_device_alloc(&client->dev, sizeof(*st)); 203 if (!indio_dev) 204 return -ENOMEM; 205 206 st = iio_priv(indio_dev); 207 i2c_set_clientdata(client, indio_dev); 208 st->client = client; 209 210 indio_dev->dev.parent = &client->dev; 211 indio_dev->name = id->name; 212 indio_dev->info = <c2497_info; 213 indio_dev->modes = INDIO_DIRECT_MODE; 214 indio_dev->channels = ltc2497_channel; 215 indio_dev->num_channels = ARRAY_SIZE(ltc2497_channel); 216 217 st->ref = devm_regulator_get(&client->dev, "vref"); 218 if (IS_ERR(st->ref)) 219 return PTR_ERR(st->ref); 220 221 ret = regulator_enable(st->ref); 222 if (ret < 0) 223 return ret; 224 225 if (client->dev.platform_data) { 226 plat_data = ((struct iio_map *)client->dev.platform_data); 227 ret = iio_map_array_register(indio_dev, plat_data); 228 if (ret) { 229 dev_err(&indio_dev->dev, "iio map err: %d\n", ret); 230 goto err_regulator_disable; 231 } 232 } 233 234 ret = i2c_smbus_write_byte(st->client, LTC2497_CONFIG_DEFAULT); 235 if (ret < 0) 236 goto err_array_unregister; 237 238 st->addr_prev = LTC2497_CONFIG_DEFAULT; 239 st->time_prev = ktime_get(); 240 241 ret = iio_device_register(indio_dev); 242 if (ret < 0) 243 goto err_array_unregister; 244 245 return 0; 246 247 err_array_unregister: 248 iio_map_array_unregister(indio_dev); 249 250 err_regulator_disable: 251 regulator_disable(st->ref); 252 253 return ret; 254 } 255 256 static int ltc2497_remove(struct i2c_client *client) 257 { 258 struct iio_dev *indio_dev = i2c_get_clientdata(client); 259 struct ltc2497_st *st = iio_priv(indio_dev); 260 261 iio_map_array_unregister(indio_dev); 262 iio_device_unregister(indio_dev); 263 regulator_disable(st->ref); 264 265 return 0; 266 } 267 268 static const struct i2c_device_id ltc2497_id[] = { 269 { "ltc2497", 0 }, 270 { } 271 }; 272 MODULE_DEVICE_TABLE(i2c, ltc2497_id); 273 274 static const struct of_device_id ltc2497_of_match[] = { 275 { .compatible = "lltc,ltc2497", }, 276 {}, 277 }; 278 MODULE_DEVICE_TABLE(of, ltc2497_of_match); 279 280 static struct i2c_driver ltc2497_driver = { 281 .driver = { 282 .name = "ltc2497", 283 .of_match_table = of_match_ptr(ltc2497_of_match), 284 }, 285 .probe = ltc2497_probe, 286 .remove = ltc2497_remove, 287 .id_table = ltc2497_id, 288 }; 289 module_i2c_driver(ltc2497_driver); 290 291 MODULE_AUTHOR("Michael Hennerich <michael.hennerich@analog.com>"); 292 MODULE_DESCRIPTION("Linear Technology LTC2497 ADC driver"); 293 MODULE_LICENSE("GPL v2"); 294