1 // SPDX-License-Identifier: GPL-2.0-only 2 /** 3 * Copyright (C) 2017 Axis Communications AB 4 * 5 * Driver for Texas Instruments' ADC084S021 ADC chip. 6 * Datasheets can be found here: 7 * https://www.ti.com/lit/ds/symlink/adc084s021.pdf 8 */ 9 10 #include <linux/err.h> 11 #include <linux/spi/spi.h> 12 #include <linux/module.h> 13 #include <linux/mod_devicetable.h> 14 #include <linux/interrupt.h> 15 #include <linux/iio/iio.h> 16 #include <linux/iio/buffer.h> 17 #include <linux/iio/triggered_buffer.h> 18 #include <linux/iio/trigger_consumer.h> 19 #include <linux/regulator/consumer.h> 20 21 #define ADC084S021_DRIVER_NAME "adc084s021" 22 23 struct adc084s021 { 24 struct spi_device *spi; 25 struct spi_message message; 26 struct spi_transfer spi_trans; 27 struct regulator *reg; 28 struct mutex lock; 29 /* Buffer used to align data */ 30 struct { 31 __be16 channels[4]; 32 s64 ts __aligned(8); 33 } scan; 34 /* 35 * DMA (thus cache coherency maintenance) requires the 36 * transfer buffers to live in their own cache line. 37 */ 38 u16 tx_buf[4] ____cacheline_aligned; 39 __be16 rx_buf[5]; /* First 16-bits are trash */ 40 }; 41 42 #define ADC084S021_VOLTAGE_CHANNEL(num) \ 43 { \ 44 .type = IIO_VOLTAGE, \ 45 .channel = (num), \ 46 .indexed = 1, \ 47 .scan_index = (num), \ 48 .scan_type = { \ 49 .sign = 'u', \ 50 .realbits = 8, \ 51 .storagebits = 16, \ 52 .shift = 4, \ 53 .endianness = IIO_BE, \ 54 }, \ 55 .info_mask_separate = BIT(IIO_CHAN_INFO_RAW), \ 56 .info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE),\ 57 } 58 59 static const struct iio_chan_spec adc084s021_channels[] = { 60 ADC084S021_VOLTAGE_CHANNEL(0), 61 ADC084S021_VOLTAGE_CHANNEL(1), 62 ADC084S021_VOLTAGE_CHANNEL(2), 63 ADC084S021_VOLTAGE_CHANNEL(3), 64 IIO_CHAN_SOFT_TIMESTAMP(4), 65 }; 66 67 /** 68 * Read an ADC channel and return its value. 69 * 70 * @adc: The ADC SPI data. 71 * @data: Buffer for converted data. 72 */ 73 static int adc084s021_adc_conversion(struct adc084s021 *adc, __be16 *data) 74 { 75 int n_words = (adc->spi_trans.len >> 1) - 1; /* Discard first word */ 76 int ret, i = 0; 77 78 /* Do the transfer */ 79 ret = spi_sync(adc->spi, &adc->message); 80 if (ret < 0) 81 return ret; 82 83 for (; i < n_words; i++) 84 *(data + i) = adc->rx_buf[i + 1]; 85 86 return ret; 87 } 88 89 static int adc084s021_read_raw(struct iio_dev *indio_dev, 90 struct iio_chan_spec const *channel, int *val, 91 int *val2, long mask) 92 { 93 struct adc084s021 *adc = iio_priv(indio_dev); 94 int ret; 95 __be16 be_val; 96 97 switch (mask) { 98 case IIO_CHAN_INFO_RAW: 99 ret = iio_device_claim_direct_mode(indio_dev); 100 if (ret < 0) 101 return ret; 102 103 ret = regulator_enable(adc->reg); 104 if (ret) { 105 iio_device_release_direct_mode(indio_dev); 106 return ret; 107 } 108 109 adc->tx_buf[0] = channel->channel << 3; 110 ret = adc084s021_adc_conversion(adc, &be_val); 111 iio_device_release_direct_mode(indio_dev); 112 regulator_disable(adc->reg); 113 if (ret < 0) 114 return ret; 115 116 *val = be16_to_cpu(be_val); 117 *val = (*val >> channel->scan_type.shift) & 0xff; 118 119 return IIO_VAL_INT; 120 case IIO_CHAN_INFO_SCALE: 121 ret = regulator_enable(adc->reg); 122 if (ret) 123 return ret; 124 125 ret = regulator_get_voltage(adc->reg); 126 regulator_disable(adc->reg); 127 if (ret < 0) 128 return ret; 129 130 *val = ret / 1000; 131 132 return IIO_VAL_INT; 133 default: 134 return -EINVAL; 135 } 136 } 137 138 /** 139 * Read enabled ADC channels and push data to the buffer. 140 * 141 * @irq: The interrupt number (not used). 142 * @pollfunc: Pointer to the poll func. 143 */ 144 static irqreturn_t adc084s021_buffer_trigger_handler(int irq, void *pollfunc) 145 { 146 struct iio_poll_func *pf = pollfunc; 147 struct iio_dev *indio_dev = pf->indio_dev; 148 struct adc084s021 *adc = iio_priv(indio_dev); 149 150 mutex_lock(&adc->lock); 151 152 if (adc084s021_adc_conversion(adc, adc->scan.channels) < 0) 153 dev_err(&adc->spi->dev, "Failed to read data\n"); 154 155 iio_push_to_buffers_with_timestamp(indio_dev, &adc->scan, 156 iio_get_time_ns(indio_dev)); 157 mutex_unlock(&adc->lock); 158 iio_trigger_notify_done(indio_dev->trig); 159 160 return IRQ_HANDLED; 161 } 162 163 static int adc084s021_buffer_preenable(struct iio_dev *indio_dev) 164 { 165 struct adc084s021 *adc = iio_priv(indio_dev); 166 int scan_index; 167 int i = 0; 168 169 for_each_set_bit(scan_index, indio_dev->active_scan_mask, 170 indio_dev->masklength) { 171 const struct iio_chan_spec *channel = 172 &indio_dev->channels[scan_index]; 173 adc->tx_buf[i++] = channel->channel << 3; 174 } 175 adc->spi_trans.len = 2 + (i * sizeof(__be16)); /* Trash + channels */ 176 177 return regulator_enable(adc->reg); 178 } 179 180 static int adc084s021_buffer_postdisable(struct iio_dev *indio_dev) 181 { 182 struct adc084s021 *adc = iio_priv(indio_dev); 183 184 adc->spi_trans.len = 4; /* Trash + single channel */ 185 186 return regulator_disable(adc->reg); 187 } 188 189 static const struct iio_info adc084s021_info = { 190 .read_raw = adc084s021_read_raw, 191 }; 192 193 static const struct iio_buffer_setup_ops adc084s021_buffer_setup_ops = { 194 .preenable = adc084s021_buffer_preenable, 195 .postdisable = adc084s021_buffer_postdisable, 196 }; 197 198 static int adc084s021_probe(struct spi_device *spi) 199 { 200 struct iio_dev *indio_dev; 201 struct adc084s021 *adc; 202 int ret; 203 204 indio_dev = devm_iio_device_alloc(&spi->dev, sizeof(*adc)); 205 if (!indio_dev) { 206 dev_err(&spi->dev, "Failed to allocate IIO device\n"); 207 return -ENOMEM; 208 } 209 210 adc = iio_priv(indio_dev); 211 adc->spi = spi; 212 213 /* Connect the SPI device and the iio dev */ 214 spi_set_drvdata(spi, indio_dev); 215 216 /* Initiate the Industrial I/O device */ 217 indio_dev->name = spi_get_device_id(spi)->name; 218 indio_dev->modes = INDIO_DIRECT_MODE; 219 indio_dev->info = &adc084s021_info; 220 indio_dev->channels = adc084s021_channels; 221 indio_dev->num_channels = ARRAY_SIZE(adc084s021_channels); 222 223 /* Create SPI transfer for channel reads */ 224 adc->spi_trans.tx_buf = adc->tx_buf; 225 adc->spi_trans.rx_buf = adc->rx_buf; 226 adc->spi_trans.len = 4; /* Trash + single channel */ 227 spi_message_init_with_transfers(&adc->message, &adc->spi_trans, 1); 228 229 adc->reg = devm_regulator_get(&spi->dev, "vref"); 230 if (IS_ERR(adc->reg)) 231 return PTR_ERR(adc->reg); 232 233 mutex_init(&adc->lock); 234 235 /* Setup triggered buffer with pollfunction */ 236 ret = devm_iio_triggered_buffer_setup(&spi->dev, indio_dev, NULL, 237 adc084s021_buffer_trigger_handler, 238 &adc084s021_buffer_setup_ops); 239 if (ret) { 240 dev_err(&spi->dev, "Failed to setup triggered buffer\n"); 241 return ret; 242 } 243 244 return devm_iio_device_register(&spi->dev, indio_dev); 245 } 246 247 static const struct of_device_id adc084s021_of_match[] = { 248 { .compatible = "ti,adc084s021", }, 249 {}, 250 }; 251 MODULE_DEVICE_TABLE(of, adc084s021_of_match); 252 253 static const struct spi_device_id adc084s021_id[] = { 254 { ADC084S021_DRIVER_NAME, 0}, 255 {} 256 }; 257 MODULE_DEVICE_TABLE(spi, adc084s021_id); 258 259 static struct spi_driver adc084s021_driver = { 260 .driver = { 261 .name = ADC084S021_DRIVER_NAME, 262 .of_match_table = adc084s021_of_match, 263 }, 264 .probe = adc084s021_probe, 265 .id_table = adc084s021_id, 266 }; 267 module_spi_driver(adc084s021_driver); 268 269 MODULE_AUTHOR("Mårten Lindahl <martenli@axis.com>"); 270 MODULE_DESCRIPTION("Texas Instruments ADC084S021"); 271 MODULE_LICENSE("GPL v2"); 272 MODULE_VERSION("1.0"); 273