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 #define LTC2309_INTERNAL_REF_MV 4096 20 21 #define LTC2309_DIN_CH_MASK GENMASK(7, 4) 22 #define LTC2309_DIN_SDN BIT(7) 23 #define LTC2309_DIN_OSN BIT(6) 24 #define LTC2309_DIN_S1 BIT(5) 25 #define LTC2309_DIN_S0 BIT(4) 26 #define LTC2309_DIN_UNI BIT(3) 27 #define LTC2309_DIN_SLEEP BIT(2) 28 29 /** 30 * struct ltc2309 - internal device data structure 31 * @dev: Device reference 32 * @client: I2C reference 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 mutex lock; /* serialize data access */ 40 int vref_mv; 41 }; 42 43 /* Order matches expected channel address, See datasheet Table 1. */ 44 enum ltc2309_channels { 45 LTC2309_CH0_CH1 = 0, 46 LTC2309_CH2_CH3, 47 LTC2309_CH4_CH5, 48 LTC2309_CH6_CH7, 49 LTC2309_CH1_CH0, 50 LTC2309_CH3_CH2, 51 LTC2309_CH5_CH4, 52 LTC2309_CH7_CH6, 53 LTC2309_CH0, 54 LTC2309_CH2, 55 LTC2309_CH4, 56 LTC2309_CH6, 57 LTC2309_CH1, 58 LTC2309_CH3, 59 LTC2309_CH5, 60 LTC2309_CH7, 61 }; 62 63 #define LTC2309_CHAN(_chan, _addr) { \ 64 .type = IIO_VOLTAGE, \ 65 .indexed = 1, \ 66 .address = _addr, \ 67 .channel = _chan, \ 68 .info_mask_separate = BIT(IIO_CHAN_INFO_RAW), \ 69 .info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE), \ 70 } 71 72 #define LTC2309_DIFF_CHAN(_chan, _chan2, _addr) { \ 73 .type = IIO_VOLTAGE, \ 74 .differential = 1, \ 75 .indexed = 1, \ 76 .address = _addr, \ 77 .channel = _chan, \ 78 .channel2 = _chan2, \ 79 .info_mask_separate = BIT(IIO_CHAN_INFO_RAW), \ 80 .info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE), \ 81 } 82 83 static const struct iio_chan_spec ltc2309_channels[] = { 84 LTC2309_CHAN(0, LTC2309_CH0), 85 LTC2309_CHAN(1, LTC2309_CH1), 86 LTC2309_CHAN(2, LTC2309_CH2), 87 LTC2309_CHAN(3, LTC2309_CH3), 88 LTC2309_CHAN(4, LTC2309_CH4), 89 LTC2309_CHAN(5, LTC2309_CH5), 90 LTC2309_CHAN(6, LTC2309_CH6), 91 LTC2309_CHAN(7, LTC2309_CH7), 92 LTC2309_DIFF_CHAN(0, 1, LTC2309_CH0_CH1), 93 LTC2309_DIFF_CHAN(2, 3, LTC2309_CH2_CH3), 94 LTC2309_DIFF_CHAN(4, 5, LTC2309_CH4_CH5), 95 LTC2309_DIFF_CHAN(6, 7, LTC2309_CH6_CH7), 96 LTC2309_DIFF_CHAN(1, 0, LTC2309_CH1_CH0), 97 LTC2309_DIFF_CHAN(3, 2, LTC2309_CH3_CH2), 98 LTC2309_DIFF_CHAN(5, 4, LTC2309_CH5_CH4), 99 LTC2309_DIFF_CHAN(7, 6, LTC2309_CH7_CH6), 100 }; 101 102 static int ltc2309_read_raw_channel(struct ltc2309 *ltc2309, 103 unsigned long address, int *val) 104 { 105 int ret; 106 u16 buf; 107 u8 din; 108 109 din = FIELD_PREP(LTC2309_DIN_CH_MASK, address & 0x0f) | 110 FIELD_PREP(LTC2309_DIN_UNI, 1) | 111 FIELD_PREP(LTC2309_DIN_SLEEP, 0); 112 113 ret = i2c_smbus_write_byte(ltc2309->client, din); 114 if (ret < 0) { 115 dev_err(ltc2309->dev, "i2c command failed: %pe\n", 116 ERR_PTR(ret)); 117 return ret; 118 } 119 120 ret = i2c_master_recv(ltc2309->client, (char *)&buf, 2); 121 if (ret < 0) { 122 dev_err(ltc2309->dev, "i2c read failed: %pe\n", ERR_PTR(ret)); 123 return ret; 124 } 125 126 *val = be16_to_cpu(buf) >> 4; 127 128 return ret; 129 } 130 131 static int ltc2309_read_raw(struct iio_dev *indio_dev, 132 struct iio_chan_spec const *chan, int *val, 133 int *val2, long mask) 134 { 135 struct ltc2309 *ltc2309 = iio_priv(indio_dev); 136 int ret; 137 138 switch (mask) { 139 case IIO_CHAN_INFO_RAW: 140 mutex_lock(<c2309->lock); 141 ret = ltc2309_read_raw_channel(ltc2309, chan->address, val); 142 mutex_unlock(<c2309->lock); 143 if (ret < 0) 144 return -EINVAL; 145 return IIO_VAL_INT; 146 case IIO_CHAN_INFO_SCALE: 147 *val = ltc2309->vref_mv; 148 *val2 = LTC2309_ADC_RESOLUTION; 149 return IIO_VAL_FRACTIONAL_LOG2; 150 default: 151 return -EINVAL; 152 } 153 } 154 155 static const struct iio_info ltc2309_info = { 156 .read_raw = ltc2309_read_raw, 157 }; 158 159 static int ltc2309_probe(struct i2c_client *client) 160 { 161 struct iio_dev *indio_dev; 162 struct ltc2309 *ltc2309; 163 int ret; 164 165 indio_dev = devm_iio_device_alloc(&client->dev, sizeof(*ltc2309)); 166 if (!indio_dev) 167 return -ENOMEM; 168 169 ltc2309 = iio_priv(indio_dev); 170 ltc2309->dev = &indio_dev->dev; 171 ltc2309->client = client; 172 173 indio_dev->name = "ltc2309"; 174 indio_dev->modes = INDIO_DIRECT_MODE; 175 indio_dev->channels = ltc2309_channels; 176 indio_dev->num_channels = ARRAY_SIZE(ltc2309_channels); 177 indio_dev->info = <c2309_info; 178 179 ret = devm_regulator_get_enable_read_voltage(&client->dev, "vref"); 180 if (ret < 0 && ret != -ENODEV) 181 return dev_err_probe(ltc2309->dev, ret, 182 "failed to get vref voltage\n"); 183 184 ltc2309->vref_mv = ret == -ENODEV ? LTC2309_INTERNAL_REF_MV : ret / 1000; 185 186 mutex_init(<c2309->lock); 187 188 return devm_iio_device_register(&client->dev, indio_dev); 189 } 190 191 static const struct of_device_id ltc2309_of_match[] = { 192 { .compatible = "lltc,ltc2309" }, 193 { } 194 }; 195 MODULE_DEVICE_TABLE(of, ltc2309_of_match); 196 197 static const struct i2c_device_id ltc2309_id[] = { 198 { "ltc2309" }, 199 { } 200 }; 201 MODULE_DEVICE_TABLE(i2c, ltc2309_id); 202 203 static struct i2c_driver ltc2309_driver = { 204 .driver = { 205 .name = "ltc2309", 206 .of_match_table = ltc2309_of_match, 207 }, 208 .probe = ltc2309_probe, 209 .id_table = ltc2309_id, 210 }; 211 module_i2c_driver(ltc2309_driver); 212 213 MODULE_AUTHOR("Liam Beguin <liambeguin@gmail.com>"); 214 MODULE_DESCRIPTION("Linear Technology LTC2309 ADC"); 215 MODULE_LICENSE("GPL v2"); 216