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/array_size.h> 13 #include <linux/bitfield.h> 14 #include <linux/delay.h> 15 #include <linux/i2c.h> 16 #include <linux/iio/iio.h> 17 #include <linux/kernel.h> 18 #include <linux/module.h> 19 #include <linux/mutex.h> 20 #include <linux/regulator/consumer.h> 21 22 #define LTC2309_ADC_RESOLUTION 12 23 #define LTC2309_INTERNAL_REF_MV 4096 24 25 #define LTC2309_DIN_CH_MASK GENMASK(7, 4) 26 #define LTC2309_DIN_SDN BIT(7) 27 #define LTC2309_DIN_OSN BIT(6) 28 #define LTC2309_DIN_S1 BIT(5) 29 #define LTC2309_DIN_S0 BIT(4) 30 #define LTC2309_DIN_UNI BIT(3) 31 #define LTC2309_DIN_SLEEP BIT(2) 32 33 /** 34 * struct ltc2309 - internal device data structure 35 * @dev: Device reference 36 * @client: I2C reference 37 * @lock: Lock to serialize data access 38 * @vref_mv: Internal voltage reference 39 * @read_delay_us: Chip-specific read delay in microseconds 40 */ 41 struct ltc2309 { 42 struct device *dev; 43 struct i2c_client *client; 44 struct mutex lock; /* serialize data access */ 45 int vref_mv; 46 unsigned int read_delay_us; 47 }; 48 49 /* Order matches expected channel address, See datasheet Table 1. */ 50 enum ltc2305_channels { 51 LTC2305_CH0_CH1 = 0x0, 52 LTC2305_CH1_CH0 = 0x4, 53 LTC2305_CH0 = 0x8, 54 LTC2305_CH1 = 0xc, 55 }; 56 57 enum ltc2309_channels { 58 LTC2309_CH0_CH1 = 0x0, 59 LTC2309_CH2_CH3 = 0x1, 60 LTC2309_CH4_CH5 = 0x2, 61 LTC2309_CH6_CH7 = 0x3, 62 LTC2309_CH1_CH0 = 0x4, 63 LTC2309_CH3_CH2 = 0x5, 64 LTC2309_CH5_CH4 = 0x6, 65 LTC2309_CH7_CH6 = 0x7, 66 LTC2309_CH0 = 0x8, 67 LTC2309_CH2 = 0x9, 68 LTC2309_CH4 = 0xa, 69 LTC2309_CH6 = 0xb, 70 LTC2309_CH1 = 0xc, 71 LTC2309_CH3 = 0xd, 72 LTC2309_CH5 = 0xe, 73 LTC2309_CH7 = 0xf, 74 }; 75 76 #define LTC2309_CHAN(_chan, _addr) { \ 77 .type = IIO_VOLTAGE, \ 78 .indexed = 1, \ 79 .address = _addr, \ 80 .channel = _chan, \ 81 .info_mask_separate = BIT(IIO_CHAN_INFO_RAW), \ 82 .info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE), \ 83 } 84 85 #define LTC2309_DIFF_CHAN(_chan, _chan2, _addr) { \ 86 .type = IIO_VOLTAGE, \ 87 .differential = 1, \ 88 .indexed = 1, \ 89 .address = _addr, \ 90 .channel = _chan, \ 91 .channel2 = _chan2, \ 92 .info_mask_separate = BIT(IIO_CHAN_INFO_RAW), \ 93 .info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE), \ 94 } 95 96 static const struct iio_chan_spec ltc2305_channels[] = { 97 LTC2309_CHAN(0, LTC2305_CH0), 98 LTC2309_CHAN(1, LTC2305_CH1), 99 LTC2309_DIFF_CHAN(0, 1, LTC2305_CH0_CH1), 100 LTC2309_DIFF_CHAN(1, 0, LTC2305_CH1_CH0), 101 }; 102 103 static const struct iio_chan_spec ltc2309_channels[] = { 104 LTC2309_CHAN(0, LTC2309_CH0), 105 LTC2309_CHAN(1, LTC2309_CH1), 106 LTC2309_CHAN(2, LTC2309_CH2), 107 LTC2309_CHAN(3, LTC2309_CH3), 108 LTC2309_CHAN(4, LTC2309_CH4), 109 LTC2309_CHAN(5, LTC2309_CH5), 110 LTC2309_CHAN(6, LTC2309_CH6), 111 LTC2309_CHAN(7, LTC2309_CH7), 112 LTC2309_DIFF_CHAN(0, 1, LTC2309_CH0_CH1), 113 LTC2309_DIFF_CHAN(2, 3, LTC2309_CH2_CH3), 114 LTC2309_DIFF_CHAN(4, 5, LTC2309_CH4_CH5), 115 LTC2309_DIFF_CHAN(6, 7, LTC2309_CH6_CH7), 116 LTC2309_DIFF_CHAN(1, 0, LTC2309_CH1_CH0), 117 LTC2309_DIFF_CHAN(3, 2, LTC2309_CH3_CH2), 118 LTC2309_DIFF_CHAN(5, 4, LTC2309_CH5_CH4), 119 LTC2309_DIFF_CHAN(7, 6, LTC2309_CH7_CH6), 120 }; 121 122 struct ltc2309_chip_info { 123 const char *name; 124 unsigned int read_delay_us; 125 int num_channels; 126 const struct iio_chan_spec *channels __counted_by_ptr(num_channels); 127 }; 128 129 static const struct ltc2309_chip_info ltc2305_chip_info = { 130 .name = "ltc2305", 131 .read_delay_us = 2, 132 .num_channels = ARRAY_SIZE(ltc2305_channels), 133 .channels = ltc2305_channels, 134 }; 135 136 static const struct ltc2309_chip_info ltc2309_chip_info = { 137 .name = "ltc2309", 138 .num_channels = ARRAY_SIZE(ltc2309_channels), 139 .channels = ltc2309_channels, 140 }; 141 142 static int ltc2309_read_raw_channel(struct ltc2309 *ltc2309, 143 unsigned long address, int *val) 144 { 145 int ret; 146 __be16 buf; 147 u8 din; 148 149 din = FIELD_PREP(LTC2309_DIN_CH_MASK, address & 0x0f) | 150 FIELD_PREP(LTC2309_DIN_UNI, 1) | 151 FIELD_PREP(LTC2309_DIN_SLEEP, 0); 152 153 ret = i2c_smbus_write_byte(ltc2309->client, din); 154 if (ret < 0) { 155 dev_err(ltc2309->dev, "i2c command failed: %pe\n", 156 ERR_PTR(ret)); 157 return ret; 158 } 159 160 if (ltc2309->read_delay_us) 161 fsleep(ltc2309->read_delay_us); 162 163 ret = i2c_master_recv(ltc2309->client, (char *)&buf, 2); 164 if (ret < 0) { 165 dev_err(ltc2309->dev, "i2c read failed: %pe\n", ERR_PTR(ret)); 166 return ret; 167 } 168 169 *val = be16_to_cpu(buf) >> 4; 170 171 return ret; 172 } 173 174 static int ltc2309_read_raw(struct iio_dev *indio_dev, 175 struct iio_chan_spec const *chan, int *val, 176 int *val2, long mask) 177 { 178 struct ltc2309 *ltc2309 = iio_priv(indio_dev); 179 int ret; 180 181 switch (mask) { 182 case IIO_CHAN_INFO_RAW: 183 mutex_lock(<c2309->lock); 184 ret = ltc2309_read_raw_channel(ltc2309, chan->address, val); 185 mutex_unlock(<c2309->lock); 186 if (ret < 0) 187 return -EINVAL; 188 return IIO_VAL_INT; 189 case IIO_CHAN_INFO_SCALE: 190 *val = ltc2309->vref_mv; 191 *val2 = LTC2309_ADC_RESOLUTION; 192 return IIO_VAL_FRACTIONAL_LOG2; 193 default: 194 return -EINVAL; 195 } 196 } 197 198 static const struct iio_info ltc2309_info = { 199 .read_raw = ltc2309_read_raw, 200 }; 201 202 static int ltc2309_probe(struct i2c_client *client) 203 { 204 const struct ltc2309_chip_info *chip_info; 205 struct iio_dev *indio_dev; 206 struct ltc2309 *ltc2309; 207 int ret; 208 209 indio_dev = devm_iio_device_alloc(&client->dev, sizeof(*ltc2309)); 210 if (!indio_dev) 211 return -ENOMEM; 212 213 ltc2309 = iio_priv(indio_dev); 214 chip_info = i2c_get_match_data(client); 215 216 ltc2309->dev = &indio_dev->dev; 217 ltc2309->client = client; 218 ltc2309->read_delay_us = chip_info->read_delay_us; 219 220 indio_dev->name = chip_info->name; 221 indio_dev->modes = INDIO_DIRECT_MODE; 222 indio_dev->channels = chip_info->channels; 223 indio_dev->num_channels = chip_info->num_channels; 224 indio_dev->info = <c2309_info; 225 226 ret = devm_regulator_get_enable_read_voltage(&client->dev, "vref"); 227 if (ret < 0 && ret != -ENODEV) 228 return dev_err_probe(ltc2309->dev, ret, 229 "failed to get vref voltage\n"); 230 231 ltc2309->vref_mv = ret == -ENODEV ? LTC2309_INTERNAL_REF_MV : ret / 1000; 232 233 mutex_init(<c2309->lock); 234 235 return devm_iio_device_register(&client->dev, indio_dev); 236 } 237 238 static const struct of_device_id ltc2309_of_match[] = { 239 { .compatible = "lltc,ltc2305", .data = <c2305_chip_info }, 240 { .compatible = "lltc,ltc2309", .data = <c2309_chip_info }, 241 { } 242 }; 243 MODULE_DEVICE_TABLE(of, ltc2309_of_match); 244 245 static const struct i2c_device_id ltc2309_id[] = { 246 { .name = "ltc2305", .driver_data = (kernel_ulong_t)<c2305_chip_info }, 247 { .name = "ltc2309", .driver_data = (kernel_ulong_t)<c2309_chip_info }, 248 { } 249 }; 250 MODULE_DEVICE_TABLE(i2c, ltc2309_id); 251 252 static struct i2c_driver ltc2309_driver = { 253 .driver = { 254 .name = "ltc2309", 255 .of_match_table = ltc2309_of_match, 256 }, 257 .probe = ltc2309_probe, 258 .id_table = ltc2309_id, 259 }; 260 module_i2c_driver(ltc2309_driver); 261 262 MODULE_AUTHOR("Liam Beguin <liambeguin@gmail.com>"); 263 MODULE_DESCRIPTION("Linear Technology LTC2309 ADC"); 264 MODULE_LICENSE("GPL v2"); 265