1 // SPDX-License-Identifier: GPL-2.0 2 /* 3 * The LTC2305 is a 2-Channel, 12-Bit SAR ADC with an I2C Interface. 4 * The LTC2309 is an 8-Channel, 12-Bit SAR ADC with an I2C Interface. 5 * 6 * Datasheet: 7 * https://www.analog.com/media/en/technical-documentation/data-sheets/23015fb.pdf 8 * https://www.analog.com/media/en/technical-documentation/data-sheets/2309fd.pdf 9 * 10 * Copyright (c) 2023, Liam Beguin <liambeguin@gmail.com> 11 */ 12 #include <linux/bitfield.h> 13 #include <linux/i2c.h> 14 #include <linux/iio/iio.h> 15 #include <linux/kernel.h> 16 #include <linux/module.h> 17 #include <linux/mutex.h> 18 #include <linux/regulator/consumer.h> 19 20 #define LTC2309_ADC_RESOLUTION 12 21 #define LTC2309_INTERNAL_REF_MV 4096 22 23 #define LTC2309_DIN_CH_MASK GENMASK(7, 4) 24 #define LTC2309_DIN_SDN BIT(7) 25 #define LTC2309_DIN_OSN BIT(6) 26 #define LTC2309_DIN_S1 BIT(5) 27 #define LTC2309_DIN_S0 BIT(4) 28 #define LTC2309_DIN_UNI BIT(3) 29 #define LTC2309_DIN_SLEEP BIT(2) 30 31 /** 32 * struct ltc2309 - internal device data structure 33 * @dev: Device reference 34 * @client: I2C reference 35 * @lock: Lock to serialize data access 36 * @vref_mv: Internal voltage reference 37 */ 38 struct ltc2309 { 39 struct device *dev; 40 struct i2c_client *client; 41 struct mutex lock; /* serialize data access */ 42 int vref_mv; 43 }; 44 45 /* Order matches expected channel address, See datasheet Table 1. */ 46 enum ltc2305_channels { 47 LTC2305_CH0_CH1 = 0x0, 48 LTC2305_CH1_CH0 = 0x4, 49 LTC2305_CH0 = 0x8, 50 LTC2305_CH1 = 0xc, 51 }; 52 53 enum ltc2309_channels { 54 LTC2309_CH0_CH1 = 0x0, 55 LTC2309_CH2_CH3 = 0x1, 56 LTC2309_CH4_CH5 = 0x2, 57 LTC2309_CH6_CH7 = 0x3, 58 LTC2309_CH1_CH0 = 0x4, 59 LTC2309_CH3_CH2 = 0x5, 60 LTC2309_CH5_CH4 = 0x6, 61 LTC2309_CH7_CH6 = 0x7, 62 LTC2309_CH0 = 0x8, 63 LTC2309_CH2 = 0x9, 64 LTC2309_CH4 = 0xa, 65 LTC2309_CH6 = 0xb, 66 LTC2309_CH1 = 0xc, 67 LTC2309_CH3 = 0xd, 68 LTC2309_CH5 = 0xe, 69 LTC2309_CH7 = 0xf, 70 }; 71 72 #define LTC2309_CHAN(_chan, _addr) { \ 73 .type = IIO_VOLTAGE, \ 74 .indexed = 1, \ 75 .address = _addr, \ 76 .channel = _chan, \ 77 .info_mask_separate = BIT(IIO_CHAN_INFO_RAW), \ 78 .info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE), \ 79 } 80 81 #define LTC2309_DIFF_CHAN(_chan, _chan2, _addr) { \ 82 .type = IIO_VOLTAGE, \ 83 .differential = 1, \ 84 .indexed = 1, \ 85 .address = _addr, \ 86 .channel = _chan, \ 87 .channel2 = _chan2, \ 88 .info_mask_separate = BIT(IIO_CHAN_INFO_RAW), \ 89 .info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE), \ 90 } 91 92 static const struct iio_chan_spec ltc2305_channels[] = { 93 LTC2309_CHAN(0, LTC2305_CH0), 94 LTC2309_CHAN(1, LTC2305_CH1), 95 LTC2309_DIFF_CHAN(0, 1, LTC2305_CH0_CH1), 96 LTC2309_DIFF_CHAN(1, 0, LTC2305_CH1_CH0), 97 }; 98 99 static const struct iio_chan_spec ltc2309_channels[] = { 100 LTC2309_CHAN(0, LTC2309_CH0), 101 LTC2309_CHAN(1, LTC2309_CH1), 102 LTC2309_CHAN(2, LTC2309_CH2), 103 LTC2309_CHAN(3, LTC2309_CH3), 104 LTC2309_CHAN(4, LTC2309_CH4), 105 LTC2309_CHAN(5, LTC2309_CH5), 106 LTC2309_CHAN(6, LTC2309_CH6), 107 LTC2309_CHAN(7, LTC2309_CH7), 108 LTC2309_DIFF_CHAN(0, 1, LTC2309_CH0_CH1), 109 LTC2309_DIFF_CHAN(2, 3, LTC2309_CH2_CH3), 110 LTC2309_DIFF_CHAN(4, 5, LTC2309_CH4_CH5), 111 LTC2309_DIFF_CHAN(6, 7, LTC2309_CH6_CH7), 112 LTC2309_DIFF_CHAN(1, 0, LTC2309_CH1_CH0), 113 LTC2309_DIFF_CHAN(3, 2, LTC2309_CH3_CH2), 114 LTC2309_DIFF_CHAN(5, 4, LTC2309_CH5_CH4), 115 LTC2309_DIFF_CHAN(7, 6, LTC2309_CH7_CH6), 116 }; 117 118 struct ltc2309_chip_info { 119 const char *name; 120 const struct iio_chan_spec *channels; 121 int num_channels; 122 }; 123 124 static const struct ltc2309_chip_info ltc2305_chip_info = { 125 .name = "ltc2305", 126 .channels = ltc2305_channels, 127 .num_channels = ARRAY_SIZE(ltc2305_channels), 128 }; 129 130 static const struct ltc2309_chip_info ltc2309_chip_info = { 131 .name = "ltc2309", 132 .channels = ltc2309_channels, 133 .num_channels = ARRAY_SIZE(ltc2309_channels), 134 }; 135 136 static int ltc2309_read_raw_channel(struct ltc2309 *ltc2309, 137 unsigned long address, int *val) 138 { 139 int ret; 140 __be16 buf; 141 u8 din; 142 143 din = FIELD_PREP(LTC2309_DIN_CH_MASK, address & 0x0f) | 144 FIELD_PREP(LTC2309_DIN_UNI, 1) | 145 FIELD_PREP(LTC2309_DIN_SLEEP, 0); 146 147 ret = i2c_smbus_write_byte(ltc2309->client, din); 148 if (ret < 0) { 149 dev_err(ltc2309->dev, "i2c command failed: %pe\n", 150 ERR_PTR(ret)); 151 return ret; 152 } 153 154 ret = i2c_master_recv(ltc2309->client, (char *)&buf, 2); 155 if (ret < 0) { 156 dev_err(ltc2309->dev, "i2c read failed: %pe\n", ERR_PTR(ret)); 157 return ret; 158 } 159 160 *val = be16_to_cpu(buf) >> 4; 161 162 return ret; 163 } 164 165 static int ltc2309_read_raw(struct iio_dev *indio_dev, 166 struct iio_chan_spec const *chan, int *val, 167 int *val2, long mask) 168 { 169 struct ltc2309 *ltc2309 = iio_priv(indio_dev); 170 int ret; 171 172 switch (mask) { 173 case IIO_CHAN_INFO_RAW: 174 mutex_lock(<c2309->lock); 175 ret = ltc2309_read_raw_channel(ltc2309, chan->address, val); 176 mutex_unlock(<c2309->lock); 177 if (ret < 0) 178 return -EINVAL; 179 return IIO_VAL_INT; 180 case IIO_CHAN_INFO_SCALE: 181 *val = ltc2309->vref_mv; 182 *val2 = LTC2309_ADC_RESOLUTION; 183 return IIO_VAL_FRACTIONAL_LOG2; 184 default: 185 return -EINVAL; 186 } 187 } 188 189 static const struct iio_info ltc2309_info = { 190 .read_raw = ltc2309_read_raw, 191 }; 192 193 static int ltc2309_probe(struct i2c_client *client) 194 { 195 const struct ltc2309_chip_info *chip_info; 196 struct iio_dev *indio_dev; 197 struct ltc2309 *ltc2309; 198 int ret; 199 200 indio_dev = devm_iio_device_alloc(&client->dev, sizeof(*ltc2309)); 201 if (!indio_dev) 202 return -ENOMEM; 203 204 ltc2309 = iio_priv(indio_dev); 205 chip_info = i2c_get_match_data(client); 206 207 ltc2309->dev = &indio_dev->dev; 208 ltc2309->client = client; 209 210 indio_dev->name = chip_info->name; 211 indio_dev->modes = INDIO_DIRECT_MODE; 212 indio_dev->channels = chip_info->channels; 213 indio_dev->num_channels = chip_info->num_channels; 214 indio_dev->info = <c2309_info; 215 216 ret = devm_regulator_get_enable_read_voltage(&client->dev, "vref"); 217 if (ret < 0 && ret != -ENODEV) 218 return dev_err_probe(ltc2309->dev, ret, 219 "failed to get vref voltage\n"); 220 221 ltc2309->vref_mv = ret == -ENODEV ? LTC2309_INTERNAL_REF_MV : ret / 1000; 222 223 mutex_init(<c2309->lock); 224 225 return devm_iio_device_register(&client->dev, indio_dev); 226 } 227 228 static const struct of_device_id ltc2309_of_match[] = { 229 { .compatible = "lltc,ltc2305", .data = <c2305_chip_info }, 230 { .compatible = "lltc,ltc2309", .data = <c2309_chip_info }, 231 { } 232 }; 233 MODULE_DEVICE_TABLE(of, ltc2309_of_match); 234 235 static const struct i2c_device_id ltc2309_id[] = { 236 { "ltc2305", (kernel_ulong_t)<c2305_chip_info }, 237 { "ltc2309", (kernel_ulong_t)<c2309_chip_info }, 238 { } 239 }; 240 MODULE_DEVICE_TABLE(i2c, ltc2309_id); 241 242 static struct i2c_driver ltc2309_driver = { 243 .driver = { 244 .name = "ltc2309", 245 .of_match_table = ltc2309_of_match, 246 }, 247 .probe = ltc2309_probe, 248 .id_table = ltc2309_id, 249 }; 250 module_i2c_driver(ltc2309_driver); 251 252 MODULE_AUTHOR("Liam Beguin <liambeguin@gmail.com>"); 253 MODULE_DESCRIPTION("Linear Technology LTC2309 ADC"); 254 MODULE_LICENSE("GPL v2"); 255