1 // SPDX-License-Identifier: GPL-2.0 2 /* 3 * Driver for Microchip MCP3911, Two-channel Analog Front End 4 * 5 * Copyright (C) 2018 Marcus Folkesson <marcus.folkesson@gmail.com> 6 * Copyright (C) 2018 Kent Gustavsson <kent@minoris.se> 7 */ 8 #include <linux/clk.h> 9 #include <linux/delay.h> 10 #include <linux/err.h> 11 #include <linux/iio/iio.h> 12 #include <linux/module.h> 13 #include <linux/regulator/consumer.h> 14 #include <linux/spi/spi.h> 15 16 #define MCP3911_REG_CHANNEL0 0x00 17 #define MCP3911_REG_CHANNEL1 0x03 18 #define MCP3911_REG_MOD 0x06 19 #define MCP3911_REG_PHASE 0x07 20 #define MCP3911_REG_GAIN 0x09 21 22 #define MCP3911_REG_STATUSCOM 0x0a 23 #define MCP3911_STATUSCOM_CH1_24WIDTH BIT(4) 24 #define MCP3911_STATUSCOM_CH0_24WIDTH BIT(3) 25 #define MCP3911_STATUSCOM_EN_OFFCAL BIT(2) 26 #define MCP3911_STATUSCOM_EN_GAINCAL BIT(1) 27 28 #define MCP3911_REG_CONFIG 0x0c 29 #define MCP3911_CONFIG_CLKEXT BIT(1) 30 #define MCP3911_CONFIG_VREFEXT BIT(2) 31 32 #define MCP3911_REG_OFFCAL_CH0 0x0e 33 #define MCP3911_REG_GAINCAL_CH0 0x11 34 #define MCP3911_REG_OFFCAL_CH1 0x14 35 #define MCP3911_REG_GAINCAL_CH1 0x17 36 #define MCP3911_REG_VREFCAL 0x1a 37 38 #define MCP3911_CHANNEL(x) (MCP3911_REG_CHANNEL0 + x * 3) 39 #define MCP3911_OFFCAL(x) (MCP3911_REG_OFFCAL_CH0 + x * 6) 40 41 /* Internal voltage reference in uV */ 42 #define MCP3911_INT_VREF_UV 1200000 43 44 #define MCP3911_REG_READ(reg, id) ((((reg) << 1) | ((id) << 5) | (1 << 0)) & 0xff) 45 #define MCP3911_REG_WRITE(reg, id) ((((reg) << 1) | ((id) << 5) | (0 << 0)) & 0xff) 46 47 #define MCP3911_NUM_CHANNELS 2 48 49 struct mcp3911 { 50 struct spi_device *spi; 51 struct mutex lock; 52 struct regulator *vref; 53 struct clk *clki; 54 u32 dev_addr; 55 }; 56 57 static int mcp3911_read(struct mcp3911 *adc, u8 reg, u32 *val, u8 len) 58 { 59 int ret; 60 61 reg = MCP3911_REG_READ(reg, adc->dev_addr); 62 ret = spi_write_then_read(adc->spi, ®, 1, val, len); 63 if (ret < 0) 64 return ret; 65 66 be32_to_cpus(val); 67 *val >>= ((4 - len) * 8); 68 dev_dbg(&adc->spi->dev, "reading 0x%x from register 0x%x\n", *val, 69 reg >> 1); 70 return ret; 71 } 72 73 static int mcp3911_write(struct mcp3911 *adc, u8 reg, u32 val, u8 len) 74 { 75 dev_dbg(&adc->spi->dev, "writing 0x%x to register 0x%x\n", val, reg); 76 77 val <<= (3 - len) * 8; 78 cpu_to_be32s(&val); 79 val |= MCP3911_REG_WRITE(reg, adc->dev_addr); 80 81 return spi_write(adc->spi, &val, len + 1); 82 } 83 84 static int mcp3911_update(struct mcp3911 *adc, u8 reg, u32 mask, 85 u32 val, u8 len) 86 { 87 u32 tmp; 88 int ret; 89 90 ret = mcp3911_read(adc, reg, &tmp, len); 91 if (ret) 92 return ret; 93 94 val &= mask; 95 val |= tmp & ~mask; 96 return mcp3911_write(adc, reg, val, len); 97 } 98 99 static int mcp3911_read_raw(struct iio_dev *indio_dev, 100 struct iio_chan_spec const *channel, int *val, 101 int *val2, long mask) 102 { 103 struct mcp3911 *adc = iio_priv(indio_dev); 104 int ret = -EINVAL; 105 106 mutex_lock(&adc->lock); 107 switch (mask) { 108 case IIO_CHAN_INFO_RAW: 109 ret = mcp3911_read(adc, 110 MCP3911_CHANNEL(channel->channel), val, 3); 111 if (ret) 112 goto out; 113 114 ret = IIO_VAL_INT; 115 break; 116 117 case IIO_CHAN_INFO_OFFSET: 118 ret = mcp3911_read(adc, 119 MCP3911_OFFCAL(channel->channel), val, 3); 120 if (ret) 121 goto out; 122 123 ret = IIO_VAL_INT; 124 break; 125 126 case IIO_CHAN_INFO_SCALE: 127 if (adc->vref) { 128 ret = regulator_get_voltage(adc->vref); 129 if (ret < 0) { 130 dev_err(indio_dev->dev.parent, 131 "failed to get vref voltage: %d\n", 132 ret); 133 goto out; 134 } 135 136 *val = ret / 1000; 137 } else { 138 *val = MCP3911_INT_VREF_UV; 139 } 140 141 *val2 = 24; 142 ret = IIO_VAL_FRACTIONAL_LOG2; 143 break; 144 } 145 146 out: 147 mutex_unlock(&adc->lock); 148 return ret; 149 } 150 151 static int mcp3911_write_raw(struct iio_dev *indio_dev, 152 struct iio_chan_spec const *channel, int val, 153 int val2, long mask) 154 { 155 struct mcp3911 *adc = iio_priv(indio_dev); 156 int ret = -EINVAL; 157 158 mutex_lock(&adc->lock); 159 switch (mask) { 160 case IIO_CHAN_INFO_OFFSET: 161 if (val2 != 0) { 162 ret = -EINVAL; 163 goto out; 164 } 165 166 /* Write offset */ 167 ret = mcp3911_write(adc, MCP3911_OFFCAL(channel->channel), val, 168 3); 169 if (ret) 170 goto out; 171 172 /* Enable offset*/ 173 ret = mcp3911_update(adc, MCP3911_REG_STATUSCOM, 174 MCP3911_STATUSCOM_EN_OFFCAL, 175 MCP3911_STATUSCOM_EN_OFFCAL, 2); 176 break; 177 } 178 179 out: 180 mutex_unlock(&adc->lock); 181 return ret; 182 } 183 184 #define MCP3911_CHAN(idx) { \ 185 .type = IIO_VOLTAGE, \ 186 .indexed = 1, \ 187 .channel = idx, \ 188 .info_mask_separate = BIT(IIO_CHAN_INFO_RAW) | \ 189 BIT(IIO_CHAN_INFO_OFFSET) | \ 190 BIT(IIO_CHAN_INFO_SCALE), \ 191 } 192 193 static const struct iio_chan_spec mcp3911_channels[] = { 194 MCP3911_CHAN(0), 195 MCP3911_CHAN(1), 196 }; 197 198 static const struct iio_info mcp3911_info = { 199 .read_raw = mcp3911_read_raw, 200 .write_raw = mcp3911_write_raw, 201 }; 202 203 static int mcp3911_config(struct mcp3911 *adc, struct device_node *of_node) 204 { 205 u32 configreg; 206 int ret; 207 208 of_property_read_u32(of_node, "device-addr", &adc->dev_addr); 209 if (adc->dev_addr > 3) { 210 dev_err(&adc->spi->dev, 211 "invalid device address (%i). Must be in range 0-3.\n", 212 adc->dev_addr); 213 return -EINVAL; 214 } 215 dev_dbg(&adc->spi->dev, "use device address %i\n", adc->dev_addr); 216 217 ret = mcp3911_read(adc, MCP3911_REG_CONFIG, &configreg, 2); 218 if (ret) 219 return ret; 220 221 if (adc->vref) { 222 dev_dbg(&adc->spi->dev, "use external voltage reference\n"); 223 configreg |= MCP3911_CONFIG_VREFEXT; 224 } else { 225 dev_dbg(&adc->spi->dev, 226 "use internal voltage reference (1.2V)\n"); 227 configreg &= ~MCP3911_CONFIG_VREFEXT; 228 } 229 230 if (adc->clki) { 231 dev_dbg(&adc->spi->dev, "use external clock as clocksource\n"); 232 configreg |= MCP3911_CONFIG_CLKEXT; 233 } else { 234 dev_dbg(&adc->spi->dev, 235 "use crystal oscillator as clocksource\n"); 236 configreg &= ~MCP3911_CONFIG_CLKEXT; 237 } 238 239 return mcp3911_write(adc, MCP3911_REG_CONFIG, configreg, 2); 240 } 241 242 static int mcp3911_probe(struct spi_device *spi) 243 { 244 struct iio_dev *indio_dev; 245 struct mcp3911 *adc; 246 int ret; 247 248 indio_dev = devm_iio_device_alloc(&spi->dev, sizeof(*adc)); 249 if (!indio_dev) 250 return -ENOMEM; 251 252 adc = iio_priv(indio_dev); 253 adc->spi = spi; 254 255 adc->vref = devm_regulator_get_optional(&adc->spi->dev, "vref"); 256 if (IS_ERR(adc->vref)) { 257 if (PTR_ERR(adc->vref) == -ENODEV) { 258 adc->vref = NULL; 259 } else { 260 dev_err(&adc->spi->dev, 261 "failed to get regulator (%ld)\n", 262 PTR_ERR(adc->vref)); 263 return PTR_ERR(adc->vref); 264 } 265 266 } else { 267 ret = regulator_enable(adc->vref); 268 if (ret) 269 return ret; 270 } 271 272 adc->clki = devm_clk_get(&adc->spi->dev, NULL); 273 if (IS_ERR(adc->clki)) { 274 if (PTR_ERR(adc->clki) == -ENOENT) { 275 adc->clki = NULL; 276 } else { 277 dev_err(&adc->spi->dev, 278 "failed to get adc clk (%ld)\n", 279 PTR_ERR(adc->clki)); 280 ret = PTR_ERR(adc->clki); 281 goto reg_disable; 282 } 283 } else { 284 ret = clk_prepare_enable(adc->clki); 285 if (ret < 0) { 286 dev_err(&adc->spi->dev, 287 "Failed to enable clki: %d\n", ret); 288 goto reg_disable; 289 } 290 } 291 292 ret = mcp3911_config(adc, spi->dev.of_node); 293 if (ret) 294 goto clk_disable; 295 296 indio_dev->name = spi_get_device_id(spi)->name; 297 indio_dev->modes = INDIO_DIRECT_MODE; 298 indio_dev->info = &mcp3911_info; 299 spi_set_drvdata(spi, indio_dev); 300 301 indio_dev->channels = mcp3911_channels; 302 indio_dev->num_channels = ARRAY_SIZE(mcp3911_channels); 303 304 mutex_init(&adc->lock); 305 306 ret = iio_device_register(indio_dev); 307 if (ret) 308 goto clk_disable; 309 310 return ret; 311 312 clk_disable: 313 clk_disable_unprepare(adc->clki); 314 reg_disable: 315 if (adc->vref) 316 regulator_disable(adc->vref); 317 318 return ret; 319 } 320 321 static int mcp3911_remove(struct spi_device *spi) 322 { 323 struct iio_dev *indio_dev = spi_get_drvdata(spi); 324 struct mcp3911 *adc = iio_priv(indio_dev); 325 326 iio_device_unregister(indio_dev); 327 328 clk_disable_unprepare(adc->clki); 329 if (adc->vref) 330 regulator_disable(adc->vref); 331 332 return 0; 333 } 334 335 static const struct of_device_id mcp3911_dt_ids[] = { 336 { .compatible = "microchip,mcp3911" }, 337 { } 338 }; 339 MODULE_DEVICE_TABLE(of, mcp3911_dt_ids); 340 341 static const struct spi_device_id mcp3911_id[] = { 342 { "mcp3911", 0 }, 343 { } 344 }; 345 MODULE_DEVICE_TABLE(spi, mcp3911_id); 346 347 static struct spi_driver mcp3911_driver = { 348 .driver = { 349 .name = "mcp3911", 350 .of_match_table = mcp3911_dt_ids, 351 }, 352 .probe = mcp3911_probe, 353 .remove = mcp3911_remove, 354 .id_table = mcp3911_id, 355 }; 356 module_spi_driver(mcp3911_driver); 357 358 MODULE_AUTHOR("Marcus Folkesson <marcus.folkesson@gmail.com>"); 359 MODULE_AUTHOR("Kent Gustavsson <kent@minoris.se>"); 360 MODULE_DESCRIPTION("Microchip Technology MCP3911"); 361 MODULE_LICENSE("GPL v2"); 362