1 // SPDX-License-Identifier: GPL-2.0 2 /* 3 * The LTC2309 is an 8-Channel, 12-Bit SAR ADC with an I2C Interface. 4 * 5 * Datasheet: 6 * https://www.analog.com/media/en/technical-documentation/data-sheets/2309fd.pdf 7 * 8 * Copyright (c) 2023, Liam Beguin <liambeguin@gmail.com> 9 */ 10 #include <linux/bitfield.h> 11 #include <linux/i2c.h> 12 #include <linux/iio/iio.h> 13 #include <linux/kernel.h> 14 #include <linux/module.h> 15 #include <linux/mutex.h> 16 #include <linux/regulator/consumer.h> 17 18 #define LTC2309_ADC_RESOLUTION 12 19 20 #define LTC2309_DIN_CH_MASK GENMASK(7, 4) 21 #define LTC2309_DIN_SDN BIT(7) 22 #define LTC2309_DIN_OSN BIT(6) 23 #define LTC2309_DIN_S1 BIT(5) 24 #define LTC2309_DIN_S0 BIT(4) 25 #define LTC2309_DIN_UNI BIT(3) 26 #define LTC2309_DIN_SLEEP BIT(2) 27 28 /** 29 * struct ltc2309 - internal device data structure 30 * @dev: Device reference 31 * @client: I2C reference 32 * @vref: External reference source 33 * @lock: Lock to serialize data access 34 * @vref_mv: Internal voltage reference 35 */ 36 struct ltc2309 { 37 struct device *dev; 38 struct i2c_client *client; 39 struct regulator *vref; 40 struct mutex lock; /* serialize data access */ 41 int vref_mv; 42 }; 43 44 /* Order matches expected channel address, See datasheet Table 1. */ 45 enum ltc2309_channels { 46 LTC2309_CH0_CH1 = 0, 47 LTC2309_CH2_CH3, 48 LTC2309_CH4_CH5, 49 LTC2309_CH6_CH7, 50 LTC2309_CH1_CH0, 51 LTC2309_CH3_CH2, 52 LTC2309_CH5_CH4, 53 LTC2309_CH7_CH6, 54 LTC2309_CH0, 55 LTC2309_CH2, 56 LTC2309_CH4, 57 LTC2309_CH6, 58 LTC2309_CH1, 59 LTC2309_CH3, 60 LTC2309_CH5, 61 LTC2309_CH7, 62 }; 63 64 #define LTC2309_CHAN(_chan, _addr) { \ 65 .type = IIO_VOLTAGE, \ 66 .indexed = 1, \ 67 .address = _addr, \ 68 .channel = _chan, \ 69 .info_mask_separate = BIT(IIO_CHAN_INFO_RAW), \ 70 .info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE), \ 71 } 72 73 #define LTC2309_DIFF_CHAN(_chan, _chan2, _addr) { \ 74 .type = IIO_VOLTAGE, \ 75 .differential = 1, \ 76 .indexed = 1, \ 77 .address = _addr, \ 78 .channel = _chan, \ 79 .channel2 = _chan2, \ 80 .info_mask_separate = BIT(IIO_CHAN_INFO_RAW), \ 81 .info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE), \ 82 } 83 84 static const struct iio_chan_spec ltc2309_channels[] = { 85 LTC2309_CHAN(0, LTC2309_CH0), 86 LTC2309_CHAN(1, LTC2309_CH1), 87 LTC2309_CHAN(2, LTC2309_CH2), 88 LTC2309_CHAN(3, LTC2309_CH3), 89 LTC2309_CHAN(4, LTC2309_CH4), 90 LTC2309_CHAN(5, LTC2309_CH5), 91 LTC2309_CHAN(6, LTC2309_CH6), 92 LTC2309_CHAN(7, LTC2309_CH7), 93 LTC2309_DIFF_CHAN(0, 1, LTC2309_CH0_CH1), 94 LTC2309_DIFF_CHAN(2, 3, LTC2309_CH2_CH3), 95 LTC2309_DIFF_CHAN(4, 5, LTC2309_CH4_CH5), 96 LTC2309_DIFF_CHAN(6, 7, LTC2309_CH6_CH7), 97 LTC2309_DIFF_CHAN(1, 0, LTC2309_CH1_CH0), 98 LTC2309_DIFF_CHAN(3, 2, LTC2309_CH3_CH2), 99 LTC2309_DIFF_CHAN(5, 4, LTC2309_CH5_CH4), 100 LTC2309_DIFF_CHAN(7, 6, LTC2309_CH7_CH6), 101 }; 102 103 static int ltc2309_read_raw_channel(struct ltc2309 *ltc2309, 104 unsigned long address, int *val) 105 { 106 int ret; 107 u16 buf; 108 u8 din; 109 110 din = FIELD_PREP(LTC2309_DIN_CH_MASK, address & 0x0f) | 111 FIELD_PREP(LTC2309_DIN_UNI, 1) | 112 FIELD_PREP(LTC2309_DIN_SLEEP, 0); 113 114 ret = i2c_smbus_write_byte(ltc2309->client, din); 115 if (ret < 0) { 116 dev_err(ltc2309->dev, "i2c command failed: %pe\n", 117 ERR_PTR(ret)); 118 return ret; 119 } 120 121 ret = i2c_master_recv(ltc2309->client, (char *)&buf, 2); 122 if (ret < 0) { 123 dev_err(ltc2309->dev, "i2c read failed: %pe\n", ERR_PTR(ret)); 124 return ret; 125 } 126 127 *val = be16_to_cpu(buf) >> 4; 128 129 return ret; 130 } 131 132 static int ltc2309_read_raw(struct iio_dev *indio_dev, 133 struct iio_chan_spec const *chan, int *val, 134 int *val2, long mask) 135 { 136 struct ltc2309 *ltc2309 = iio_priv(indio_dev); 137 int ret; 138 139 switch (mask) { 140 case IIO_CHAN_INFO_RAW: 141 mutex_lock(<c2309->lock); 142 ret = ltc2309_read_raw_channel(ltc2309, chan->address, val); 143 mutex_unlock(<c2309->lock); 144 if (ret < 0) 145 return -EINVAL; 146 return IIO_VAL_INT; 147 case IIO_CHAN_INFO_SCALE: 148 *val = ltc2309->vref_mv; 149 *val2 = LTC2309_ADC_RESOLUTION; 150 return IIO_VAL_FRACTIONAL_LOG2; 151 default: 152 return -EINVAL; 153 } 154 } 155 156 static const struct iio_info ltc2309_info = { 157 .read_raw = ltc2309_read_raw, 158 }; 159 160 static void ltc2309_regulator_disable(void *regulator) 161 { 162 regulator_disable(regulator); 163 } 164 165 static int ltc2309_probe(struct i2c_client *client) 166 { 167 struct iio_dev *indio_dev; 168 struct ltc2309 *ltc2309; 169 int ret; 170 171 indio_dev = devm_iio_device_alloc(&client->dev, sizeof(*ltc2309)); 172 if (!indio_dev) 173 return -ENOMEM; 174 175 ltc2309 = iio_priv(indio_dev); 176 ltc2309->dev = &indio_dev->dev; 177 ltc2309->client = client; 178 ltc2309->vref_mv = 4096; /* Default to the internal ref */ 179 180 indio_dev->name = "ltc2309"; 181 indio_dev->modes = INDIO_DIRECT_MODE; 182 indio_dev->channels = ltc2309_channels; 183 indio_dev->num_channels = ARRAY_SIZE(ltc2309_channels); 184 indio_dev->info = <c2309_info; 185 186 ltc2309->vref = devm_regulator_get_optional(&client->dev, "vref"); 187 if (IS_ERR(ltc2309->vref)) { 188 ret = PTR_ERR(ltc2309->vref); 189 if (ret == -ENODEV) 190 ltc2309->vref = NULL; 191 else 192 return ret; 193 } 194 195 if (ltc2309->vref) { 196 ret = regulator_enable(ltc2309->vref); 197 if (ret) 198 return dev_err_probe(ltc2309->dev, ret, 199 "failed to enable vref\n"); 200 201 ret = devm_add_action_or_reset(ltc2309->dev, 202 ltc2309_regulator_disable, 203 ltc2309->vref); 204 if (ret) { 205 return dev_err_probe(ltc2309->dev, ret, 206 "failed to add regulator_disable action: %d\n", 207 ret); 208 } 209 210 ret = regulator_get_voltage(ltc2309->vref); 211 if (ret < 0) 212 return ret; 213 214 ltc2309->vref_mv = ret / 1000; 215 } 216 217 mutex_init(<c2309->lock); 218 219 return devm_iio_device_register(&client->dev, indio_dev); 220 } 221 222 static const struct of_device_id ltc2309_of_match[] = { 223 { .compatible = "lltc,ltc2309" }, 224 { } 225 }; 226 MODULE_DEVICE_TABLE(of, ltc2309_of_match); 227 228 static const struct i2c_device_id ltc2309_id[] = { 229 { "ltc2309" }, 230 { } 231 }; 232 MODULE_DEVICE_TABLE(i2c, ltc2309_id); 233 234 static struct i2c_driver ltc2309_driver = { 235 .driver = { 236 .name = "ltc2309", 237 .of_match_table = ltc2309_of_match, 238 }, 239 .probe = ltc2309_probe, 240 .id_table = ltc2309_id, 241 }; 242 module_i2c_driver(ltc2309_driver); 243 244 MODULE_AUTHOR("Liam Beguin <liambeguin@gmail.com>"); 245 MODULE_DESCRIPTION("Linear Technology LTC2309 ADC"); 246 MODULE_LICENSE("GPL v2"); 247