1 // SPDX-License-Identifier: GPL-2.0-only 2 /* 3 * MMC5983 - MEMSIC 3-axis Magnetic Sensor 4 * 5 * Copyright (c) 2026, Vlad Kulikov <vlad.kulikov.c@gmail.com> 6 * 7 * IIO driver for MMC5983 8 */ 9 10 #include <linux/array_size.h> 11 #include <linux/bits.h> 12 #include <linux/cleanup.h> 13 #include <linux/delay.h> 14 #include <linux/dev_printk.h> 15 #include <linux/err.h> 16 #include <linux/i2c.h> 17 #include <linux/iio/iio.h> 18 #include <linux/module.h> 19 #include <linux/mutex.h> 20 #include <linux/regmap.h> 21 #include <linux/time.h> 22 #include <linux/types.h> 23 24 #define MMC5983_REG_XOUT0 0x00 25 #define MMC5983_REG_XOUT1 0x01 26 #define MMC5983_REG_YOUT0 0x02 27 #define MMC5983_REG_YOUT1 0x03 28 #define MMC5983_REG_ZOUT0 0x04 29 #define MMC5983_REG_ZOUT1 0x05 30 #define MMC5983_REG_XYZOUT2 0x06 31 32 #define MMC5983_REG_STATUS 0x08 33 34 #define MMC5983_REG_CTRL0 0x09 35 #define MMC5983_REG_CTRL1 0x0A 36 #define MMC5983_REG_CTRL2 0x0B 37 #define MMC5983_REG_CTRL3 0x0C 38 39 #define MMC5983_REG_ID 0x2F 40 41 #define MMC5983_PRODUCT_ID 0x30 42 43 #define MMC5983_STATUS_MEAS_M_DONE_BIT BIT(0) 44 #define MMC5983_STATUS_OTP_RD_DONE_BIT BIT(4) 45 46 #define MMC5983_CTRL0_TM_M_BIT BIT(0) 47 #define MMC5983_CTRL0_SET_BIT BIT(3) 48 #define MMC5983_CTRL0_RESET_BIT BIT(4) 49 #define MMC5983_CTRL0_OTP_RD_BIT BIT(6) 50 51 #define MMC5983_CTRL1_SW_RST_BIT BIT(7) 52 53 enum mmc5983_axis { 54 MMC5983_AXIS_X, 55 MMC5983_AXIS_Y, 56 MMC5983_AXIS_Z, 57 }; 58 59 struct mmc5983_data { 60 struct regmap *regmap; 61 /* Protects chip access during SET/RESET measurement sequence */ 62 struct mutex mutex; 63 }; 64 65 #define MMC5983_CHANNEL(_axis) { \ 66 .type = IIO_MAGN, \ 67 .modified = 1, \ 68 .channel2 = IIO_MOD_##_axis, \ 69 .address = MMC5983_AXIS_##_axis, \ 70 .info_mask_separate = BIT(IIO_CHAN_INFO_RAW), \ 71 .info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE), \ 72 } 73 74 static const struct iio_chan_spec mmc5983_channels[] = { 75 MMC5983_CHANNEL(X), 76 MMC5983_CHANNEL(Y), 77 MMC5983_CHANNEL(Z), 78 }; 79 80 static int mmc5983_pulse_coil(struct mmc5983_data *data, unsigned int coil_bit) 81 { 82 int ret; 83 84 ret = regmap_write(data->regmap, MMC5983_REG_CTRL0, coil_bit); 85 if (ret) 86 return ret; 87 88 /* 89 * Datasheet page 15: SET/RESET coil pulse is 500 ns. 90 * Vendor sample code waits 500 us before the next operation. 91 */ 92 fsleep(500); 93 94 return 0; 95 } 96 97 static int mmc5983_take_measurement(struct mmc5983_data *data, int m[3]) 98 { 99 unsigned int status; 100 u8 buf[7]; 101 int ret; 102 103 ret = regmap_write(data->regmap, MMC5983_REG_CTRL0, 104 MMC5983_CTRL0_TM_M_BIT); 105 if (ret) 106 return ret; 107 108 /* 109 * Datasheet page 15: measurement time is 8 ms at BW=00 (default, 110 * slowest setting). Use a 50 ms timeout for margin. 111 */ 112 ret = regmap_read_poll_timeout(data->regmap, MMC5983_REG_STATUS, 113 status, 114 status & MMC5983_STATUS_MEAS_M_DONE_BIT, 115 10 * USEC_PER_MSEC, 116 50 * USEC_PER_MSEC); 117 if (ret) 118 return ret; 119 120 ret = regmap_bulk_read(data->regmap, MMC5983_REG_XOUT0, buf, 121 sizeof(buf)); 122 if (ret) 123 return ret; 124 125 m[0] = (buf[0] << 10) | (buf[1] << 2) | ((buf[6] >> 6) & 0x3); 126 m[1] = (buf[2] << 10) | (buf[3] << 2) | ((buf[6] >> 4) & 0x3); 127 m[2] = (buf[4] << 10) | (buf[5] << 2) | ((buf[6] >> 2) & 0x3); 128 129 return 0; 130 } 131 132 static int mmc5983_read_raw(struct iio_dev *indio_dev, 133 const struct iio_chan_spec *chan, int *val, 134 int *val2, long mask) 135 { 136 struct mmc5983_data *data = iio_priv(indio_dev); 137 int m1[3], m2[3]; 138 int ret; 139 140 switch (mask) { 141 case IIO_CHAN_INFO_RAW: { 142 guard(mutex)(&data->mutex); 143 144 /* SET: magnetize sensor elements in forward direction */ 145 ret = mmc5983_pulse_coil(data, MMC5983_CTRL0_SET_BIT); 146 if (ret) 147 return ret; 148 149 ret = mmc5983_take_measurement(data, m1); 150 if (ret) 151 return ret; 152 153 /* RESET: magnetize sensor elements in reverse direction */ 154 ret = mmc5983_pulse_coil(data, MMC5983_CTRL0_RESET_BIT); 155 if (ret) 156 return ret; 157 158 ret = mmc5983_take_measurement(data, m2); 159 if (ret) 160 return ret; 161 162 *val = (m1[chan->address] - m2[chan->address]) / 2; 163 return IIO_VAL_INT; 164 } 165 case IIO_CHAN_INFO_SCALE: 166 *val = 0; 167 *val2 = 61035; 168 return IIO_VAL_INT_PLUS_NANO; 169 default: 170 return -EINVAL; 171 } 172 } 173 174 static const struct iio_info mmc5983_info = { 175 .read_raw = mmc5983_read_raw, 176 }; 177 178 static bool mmc5983_is_writeable_reg(struct device *dev, unsigned int reg) 179 { 180 switch (reg) { 181 case MMC5983_REG_CTRL0: 182 case MMC5983_REG_CTRL1: 183 case MMC5983_REG_CTRL2: 184 case MMC5983_REG_CTRL3: 185 return true; 186 default: 187 return false; 188 } 189 } 190 191 static bool mmc5983_is_readable_reg(struct device *dev, unsigned int reg) 192 { 193 switch (reg) { 194 case MMC5983_REG_XOUT0: 195 case MMC5983_REG_XOUT1: 196 case MMC5983_REG_YOUT0: 197 case MMC5983_REG_YOUT1: 198 case MMC5983_REG_ZOUT0: 199 case MMC5983_REG_ZOUT1: 200 case MMC5983_REG_XYZOUT2: 201 case MMC5983_REG_STATUS: 202 case MMC5983_REG_CTRL0: 203 case MMC5983_REG_CTRL1: 204 case MMC5983_REG_CTRL2: 205 case MMC5983_REG_CTRL3: 206 case MMC5983_REG_ID: 207 return true; 208 default: 209 return false; 210 } 211 } 212 213 static bool mmc5983_is_volatile_reg(struct device *dev, unsigned int reg) 214 { 215 switch (reg) { 216 case MMC5983_REG_XOUT0: 217 case MMC5983_REG_XOUT1: 218 case MMC5983_REG_YOUT0: 219 case MMC5983_REG_YOUT1: 220 case MMC5983_REG_ZOUT0: 221 case MMC5983_REG_ZOUT1: 222 case MMC5983_REG_XYZOUT2: 223 case MMC5983_REG_STATUS: 224 case MMC5983_REG_CTRL0: 225 case MMC5983_REG_CTRL1: 226 return true; 227 default: 228 return false; 229 } 230 } 231 232 static const struct regmap_config mmc5983_regmap_config = { 233 .name = "mmc5983_regmap", 234 .reg_bits = 8, 235 .val_bits = 8, 236 .max_register = MMC5983_REG_ID, 237 .writeable_reg = mmc5983_is_writeable_reg, 238 .readable_reg = mmc5983_is_readable_reg, 239 .volatile_reg = mmc5983_is_volatile_reg, 240 }; 241 242 static int mmc5983_init(struct mmc5983_data *data) 243 { 244 struct regmap *regmap = data->regmap; 245 struct device *dev = regmap_get_device(regmap); 246 unsigned int reg_id, status; 247 int ret; 248 249 ret = regmap_read(regmap, MMC5983_REG_ID, ®_id); 250 if (ret) 251 return dev_err_probe(dev, ret, "Error reading product id\n"); 252 253 if (reg_id != MMC5983_PRODUCT_ID) 254 dev_info(dev, "unexpected product id 0x%02x\n", reg_id); 255 256 ret = regmap_write(regmap, MMC5983_REG_CTRL1, MMC5983_CTRL1_SW_RST_BIT); 257 if (ret) 258 return ret; 259 260 /* Datasheet page 15: power-on time after SW_RST is 10 ms */ 261 fsleep(10 * USEC_PER_MSEC); 262 263 ret = regmap_write(regmap, MMC5983_REG_CTRL0, MMC5983_CTRL0_OTP_RD_BIT); 264 if (ret) 265 return ret; 266 267 /* 268 * Datasheet page 15: OTP read completes and self-clears. No separate 269 * OTP refresh timeout is specified, so use the 10 ms power-on time as 270 * a conservative upper bound. 271 */ 272 ret = regmap_read_poll_timeout(regmap, MMC5983_REG_STATUS, status, 273 status & MMC5983_STATUS_OTP_RD_DONE_BIT, 274 USEC_PER_MSEC, 275 10 * USEC_PER_MSEC); 276 if (ret) 277 return ret; 278 279 /* SET: magnetize sensor elements in forward direction */ 280 ret = mmc5983_pulse_coil(data, MMC5983_CTRL0_SET_BIT); 281 if (ret) 282 return ret; 283 284 /* RESET: magnetize sensor elements in reverse direction */ 285 return mmc5983_pulse_coil(data, MMC5983_CTRL0_RESET_BIT); 286 } 287 288 static int mmc5983_probe(struct i2c_client *i2c) 289 { 290 struct device *dev = &i2c->dev; 291 struct mmc5983_data *data; 292 struct iio_dev *indio_dev; 293 int ret; 294 295 indio_dev = devm_iio_device_alloc(dev, sizeof(*data)); 296 if (!indio_dev) 297 return -ENOMEM; 298 299 data = iio_priv(indio_dev); 300 301 ret = devm_mutex_init(dev, &data->mutex); 302 if (ret) 303 return ret; 304 305 data->regmap = devm_regmap_init_i2c(i2c, &mmc5983_regmap_config); 306 if (IS_ERR(data->regmap)) 307 return dev_err_probe(dev, PTR_ERR(data->regmap), 308 "failed to allocate register map\n"); 309 310 indio_dev->info = &mmc5983_info; 311 indio_dev->modes = INDIO_DIRECT_MODE; 312 indio_dev->name = "mmc5983"; 313 indio_dev->channels = mmc5983_channels; 314 indio_dev->num_channels = ARRAY_SIZE(mmc5983_channels); 315 316 ret = mmc5983_init(data); 317 if (ret) 318 return dev_err_probe(dev, ret, "mmc5983 chip init failed\n"); 319 320 return devm_iio_device_register(dev, indio_dev); 321 } 322 323 static const struct of_device_id mmc5983_of_match[] = { 324 { .compatible = "memsic,mmc5983" }, 325 { } 326 }; 327 MODULE_DEVICE_TABLE(of, mmc5983_of_match); 328 329 static const struct i2c_device_id mmc5983_id[] = { 330 { .name = "mmc5983" }, 331 { } 332 }; 333 MODULE_DEVICE_TABLE(i2c, mmc5983_id); 334 335 static struct i2c_driver mmc5983_driver = { 336 .driver = { 337 .name = "mmc5983", 338 .of_match_table = mmc5983_of_match, 339 }, 340 .probe = mmc5983_probe, 341 .id_table = mmc5983_id, 342 }; 343 module_i2c_driver(mmc5983_driver); 344 345 MODULE_AUTHOR("Vladislav Kulikov <vlad.kulikov.c@gmail.com>"); 346 MODULE_DESCRIPTION("MEMSIC MMC5983 magnetic sensor driver"); 347 MODULE_LICENSE("GPL"); 348