1 /** 2 * Copyright (C) 2017 Axis Communications AB 3 * 4 * Driver for Texas Instruments' ADC084S021 ADC chip. 5 * Datasheets can be found here: 6 * http://www.ti.com/lit/ds/symlink/adc084s021.pdf 7 * 8 * This program is free software; you can redistribute it and/or modify 9 * it under the terms of the GNU General Public License version 2 as 10 * published by the Free Software Foundation. 11 */ 12 13 #include <linux/err.h> 14 #include <linux/spi/spi.h> 15 #include <linux/module.h> 16 #include <linux/interrupt.h> 17 #include <linux/iio/iio.h> 18 #include <linux/iio/buffer.h> 19 #include <linux/iio/triggered_buffer.h> 20 #include <linux/iio/trigger_consumer.h> 21 #include <linux/regulator/consumer.h> 22 23 #define ADC084S021_DRIVER_NAME "adc084s021" 24 25 struct adc084s021 { 26 struct spi_device *spi; 27 struct spi_message message; 28 struct spi_transfer spi_trans; 29 struct regulator *reg; 30 struct mutex lock; 31 /* 32 * DMA (thus cache coherency maintenance) requires the 33 * transfer buffers to live in their own cache line. 34 */ 35 u16 tx_buf[4] ____cacheline_aligned; 36 __be16 rx_buf[5]; /* First 16-bits are trash */ 37 }; 38 39 #define ADC084S021_VOLTAGE_CHANNEL(num) \ 40 { \ 41 .type = IIO_VOLTAGE, \ 42 .channel = (num), \ 43 .indexed = 1, \ 44 .scan_index = (num), \ 45 .scan_type = { \ 46 .sign = 'u', \ 47 .realbits = 8, \ 48 .storagebits = 16, \ 49 .shift = 4, \ 50 .endianness = IIO_BE, \ 51 }, \ 52 .info_mask_separate = BIT(IIO_CHAN_INFO_RAW), \ 53 .info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE),\ 54 } 55 56 static const struct iio_chan_spec adc084s021_channels[] = { 57 ADC084S021_VOLTAGE_CHANNEL(0), 58 ADC084S021_VOLTAGE_CHANNEL(1), 59 ADC084S021_VOLTAGE_CHANNEL(2), 60 ADC084S021_VOLTAGE_CHANNEL(3), 61 IIO_CHAN_SOFT_TIMESTAMP(4), 62 }; 63 64 /** 65 * Read an ADC channel and return its value. 66 * 67 * @adc: The ADC SPI data. 68 * @data: Buffer for converted data. 69 */ 70 static int adc084s021_adc_conversion(struct adc084s021 *adc, void *data) 71 { 72 int n_words = (adc->spi_trans.len >> 1) - 1; /* Discard first word */ 73 int ret, i = 0; 74 u16 *p = data; 75 76 /* Do the transfer */ 77 ret = spi_sync(adc->spi, &adc->message); 78 if (ret < 0) 79 return ret; 80 81 for (; i < n_words; i++) 82 *(p + i) = adc->rx_buf[i + 1]; 83 84 return ret; 85 } 86 87 static int adc084s021_read_raw(struct iio_dev *indio_dev, 88 struct iio_chan_spec const *channel, int *val, 89 int *val2, long mask) 90 { 91 struct adc084s021 *adc = iio_priv(indio_dev); 92 int ret; 93 94 switch (mask) { 95 case IIO_CHAN_INFO_RAW: 96 ret = iio_device_claim_direct_mode(indio_dev); 97 if (ret < 0) 98 return ret; 99 100 ret = regulator_enable(adc->reg); 101 if (ret) { 102 iio_device_release_direct_mode(indio_dev); 103 return ret; 104 } 105 106 adc->tx_buf[0] = channel->channel << 3; 107 ret = adc084s021_adc_conversion(adc, val); 108 iio_device_release_direct_mode(indio_dev); 109 regulator_disable(adc->reg); 110 if (ret < 0) 111 return ret; 112 113 *val = be16_to_cpu(*val); 114 *val = (*val >> channel->scan_type.shift) & 0xff; 115 116 return IIO_VAL_INT; 117 case IIO_CHAN_INFO_SCALE: 118 ret = regulator_enable(adc->reg); 119 if (ret) 120 return ret; 121 122 ret = regulator_get_voltage(adc->reg); 123 regulator_disable(adc->reg); 124 if (ret < 0) 125 return ret; 126 127 *val = ret / 1000; 128 129 return IIO_VAL_INT; 130 default: 131 return -EINVAL; 132 } 133 } 134 135 /** 136 * Read enabled ADC channels and push data to the buffer. 137 * 138 * @irq: The interrupt number (not used). 139 * @pollfunc: Pointer to the poll func. 140 */ 141 static irqreturn_t adc084s021_buffer_trigger_handler(int irq, void *pollfunc) 142 { 143 struct iio_poll_func *pf = pollfunc; 144 struct iio_dev *indio_dev = pf->indio_dev; 145 struct adc084s021 *adc = iio_priv(indio_dev); 146 __be16 data[8] = {0}; /* 4 * 16-bit words of data + 8 bytes timestamp */ 147 148 mutex_lock(&adc->lock); 149 150 if (adc084s021_adc_conversion(adc, &data) < 0) 151 dev_err(&adc->spi->dev, "Failed to read data\n"); 152 153 iio_push_to_buffers_with_timestamp(indio_dev, data, 154 iio_get_time_ns(indio_dev)); 155 mutex_unlock(&adc->lock); 156 iio_trigger_notify_done(indio_dev->trig); 157 158 return IRQ_HANDLED; 159 } 160 161 static int adc084s021_buffer_preenable(struct iio_dev *indio_dev) 162 { 163 struct adc084s021 *adc = iio_priv(indio_dev); 164 int scan_index; 165 int i = 0; 166 167 for_each_set_bit(scan_index, indio_dev->active_scan_mask, 168 indio_dev->masklength) { 169 const struct iio_chan_spec *channel = 170 &indio_dev->channels[scan_index]; 171 adc->tx_buf[i++] = channel->channel << 3; 172 } 173 adc->spi_trans.len = 2 + (i * sizeof(__be16)); /* Trash + channels */ 174 175 return regulator_enable(adc->reg); 176 } 177 178 static int adc084s021_buffer_postdisable(struct iio_dev *indio_dev) 179 { 180 struct adc084s021 *adc = iio_priv(indio_dev); 181 182 adc->spi_trans.len = 4; /* Trash + single channel */ 183 184 return regulator_disable(adc->reg); 185 } 186 187 static const struct iio_info adc084s021_info = { 188 .read_raw = adc084s021_read_raw, 189 }; 190 191 static const struct iio_buffer_setup_ops adc084s021_buffer_setup_ops = { 192 .preenable = adc084s021_buffer_preenable, 193 .postenable = iio_triggered_buffer_postenable, 194 .predisable = iio_triggered_buffer_predisable, 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->dev.parent = &spi->dev; 218 indio_dev->dev.of_node = spi->dev.of_node; 219 indio_dev->name = spi_get_device_id(spi)->name; 220 indio_dev->modes = INDIO_DIRECT_MODE; 221 indio_dev->info = &adc084s021_info; 222 indio_dev->channels = adc084s021_channels; 223 indio_dev->num_channels = ARRAY_SIZE(adc084s021_channels); 224 225 /* Create SPI transfer for channel reads */ 226 adc->spi_trans.tx_buf = adc->tx_buf; 227 adc->spi_trans.rx_buf = adc->rx_buf; 228 adc->spi_trans.len = 4; /* Trash + single channel */ 229 spi_message_init_with_transfers(&adc->message, &adc->spi_trans, 1); 230 231 adc->reg = devm_regulator_get(&spi->dev, "vref"); 232 if (IS_ERR(adc->reg)) 233 return PTR_ERR(adc->reg); 234 235 mutex_init(&adc->lock); 236 237 /* Setup triggered buffer with pollfunction */ 238 ret = devm_iio_triggered_buffer_setup(&spi->dev, indio_dev, NULL, 239 adc084s021_buffer_trigger_handler, 240 &adc084s021_buffer_setup_ops); 241 if (ret) { 242 dev_err(&spi->dev, "Failed to setup triggered buffer\n"); 243 return ret; 244 } 245 246 return devm_iio_device_register(&spi->dev, indio_dev); 247 } 248 249 static const struct of_device_id adc084s021_of_match[] = { 250 { .compatible = "ti,adc084s021", }, 251 {}, 252 }; 253 MODULE_DEVICE_TABLE(of, adc084s021_of_match); 254 255 static const struct spi_device_id adc084s021_id[] = { 256 { ADC084S021_DRIVER_NAME, 0}, 257 {} 258 }; 259 MODULE_DEVICE_TABLE(spi, adc084s021_id); 260 261 static struct spi_driver adc084s021_driver = { 262 .driver = { 263 .name = ADC084S021_DRIVER_NAME, 264 .of_match_table = of_match_ptr(adc084s021_of_match), 265 }, 266 .probe = adc084s021_probe, 267 .id_table = adc084s021_id, 268 }; 269 module_spi_driver(adc084s021_driver); 270 271 MODULE_AUTHOR("Mårten Lindahl <martenli@axis.com>"); 272 MODULE_DESCRIPTION("Texas Instruments ADC084S021"); 273 MODULE_LICENSE("GPL v2"); 274 MODULE_VERSION("1.0"); 275