--- /dev/null
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * MMC5983 - MEMSIC 3-axis Magnetic Sensor
+ *
+ * Copyright (c) 2026, Vlad Kulikov <vlad.kulikov.c@gmail.com>
+ *
+ * IIO driver for MMC5983
+ */
+
+#include <linux/array_size.h>
+#include <linux/bits.h>
+#include <linux/cleanup.h>
+#include <linux/delay.h>
+#include <linux/dev_printk.h>
+#include <linux/err.h>
+#include <linux/i2c.h>
+#include <linux/iio/iio.h>
+#include <linux/mod_devicetable.h>
+#include <linux/module.h>
+#include <linux/mutex.h>
+#include <linux/regmap.h>
+#include <linux/time.h>
+#include <linux/types.h>
+
+#define MMC5983_REG_XOUT0 0x00
+#define MMC5983_REG_XOUT1 0x01
+#define MMC5983_REG_YOUT0 0x02
+#define MMC5983_REG_YOUT1 0x03
+#define MMC5983_REG_ZOUT0 0x04
+#define MMC5983_REG_ZOUT1 0x05
+#define MMC5983_REG_XYZOUT2 0x06
+
+#define MMC5983_REG_STATUS 0x08
+
+#define MMC5983_REG_CTRL0 0x09
+#define MMC5983_REG_CTRL1 0x0A
+#define MMC5983_REG_CTRL2 0x0B
+#define MMC5983_REG_CTRL3 0x0C
+
+#define MMC5983_REG_ID 0x2F
+
+#define MMC5983_PRODUCT_ID 0x30
+
+#define MMC5983_STATUS_MEAS_M_DONE_BIT BIT(0)
+#define MMC5983_STATUS_OTP_RD_DONE_BIT BIT(4)
+
+#define MMC5983_CTRL0_TM_M_BIT BIT(0)
+#define MMC5983_CTRL0_SET_BIT BIT(3)
+#define MMC5983_CTRL0_RESET_BIT BIT(4)
+#define MMC5983_CTRL0_OTP_RD_BIT BIT(6)
+
+#define MMC5983_CTRL1_SW_RST_BIT BIT(7)
+
+enum mmc5983_axis {
+ MMC5983_AXIS_X,
+ MMC5983_AXIS_Y,
+ MMC5983_AXIS_Z,
+};
+
+struct mmc5983_data {
+ struct regmap *regmap;
+ /* Protects chip access during SET/RESET measurement sequence */
+ struct mutex mutex;
+};
+
+#define MMC5983_CHANNEL(_axis) { \
+ .type = IIO_MAGN, \
+ .modified = 1, \
+ .channel2 = IIO_MOD_##_axis, \
+ .address = MMC5983_AXIS_##_axis, \
+ .info_mask_separate = BIT(IIO_CHAN_INFO_RAW), \
+ .info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE), \
+}
+
+static const struct iio_chan_spec mmc5983_channels[] = {
+ MMC5983_CHANNEL(X),
+ MMC5983_CHANNEL(Y),
+ MMC5983_CHANNEL(Z),
+};
+
+static int mmc5983_pulse_coil(struct mmc5983_data *data, unsigned int coil_bit)
+{
+ int ret;
+
+ ret = regmap_write(data->regmap, MMC5983_REG_CTRL0, coil_bit);
+ if (ret)
+ return ret;
+
+ /*
+ * Datasheet page 15: SET/RESET coil pulse is 500 ns.
+ * Vendor sample code waits 500 us before the next operation.
+ */
+ fsleep(500);
+
+ return 0;
+}
+
+static int mmc5983_take_measurement(struct mmc5983_data *data, int m[3])
+{
+ unsigned int status;
+ u8 buf[7];
+ int ret;
+
+ ret = regmap_write(data->regmap, MMC5983_REG_CTRL0,
+ MMC5983_CTRL0_TM_M_BIT);
+ if (ret)
+ return ret;
+
+ /*
+ * Datasheet page 15: measurement time is 8 ms at BW=00 (default,
+ * slowest setting). Use a 50 ms timeout for margin.
+ */
+ ret = regmap_read_poll_timeout(data->regmap, MMC5983_REG_STATUS,
+ status,
+ status & MMC5983_STATUS_MEAS_M_DONE_BIT,
+ 10 * USEC_PER_MSEC,
+ 50 * USEC_PER_MSEC);
+ if (ret)
+ return ret;
+
+ ret = regmap_bulk_read(data->regmap, MMC5983_REG_XOUT0, buf,
+ sizeof(buf));
+ if (ret)
+ return ret;
+
+ m[0] = (buf[0] << 10) | (buf[1] << 2) | ((buf[6] >> 6) & 0x3);
+ m[1] = (buf[2] << 10) | (buf[3] << 2) | ((buf[6] >> 4) & 0x3);
+ m[2] = (buf[4] << 10) | (buf[5] << 2) | ((buf[6] >> 2) & 0x3);
+
+ return 0;
+}
+
+static int mmc5983_read_raw(struct iio_dev *indio_dev,
+ const struct iio_chan_spec *chan, int *val,
+ int *val2, long mask)
+{
+ struct mmc5983_data *data = iio_priv(indio_dev);
+ int m1[3], m2[3];
+ int ret;
+
+ switch (mask) {
+ case IIO_CHAN_INFO_RAW: {
+ guard(mutex)(&data->mutex);
+
+ /* SET: magnetize sensor elements in forward direction */
+ ret = mmc5983_pulse_coil(data, MMC5983_CTRL0_SET_BIT);
+ if (ret)
+ return ret;
+
+ ret = mmc5983_take_measurement(data, m1);
+ if (ret)
+ return ret;
+
+ /* RESET: magnetize sensor elements in reverse direction */
+ ret = mmc5983_pulse_coil(data, MMC5983_CTRL0_RESET_BIT);
+ if (ret)
+ return ret;
+
+ ret = mmc5983_take_measurement(data, m2);
+ if (ret)
+ return ret;
+
+ *val = (m1[chan->address] - m2[chan->address]) / 2;
+ return IIO_VAL_INT;
+ }
+ case IIO_CHAN_INFO_SCALE:
+ *val = 0;
+ *val2 = 61035;
+ return IIO_VAL_INT_PLUS_NANO;
+ default:
+ return -EINVAL;
+ }
+}
+
+static const struct iio_info mmc5983_info = {
+ .read_raw = mmc5983_read_raw,
+};
+
+static bool mmc5983_is_writeable_reg(struct device *dev, unsigned int reg)
+{
+ switch (reg) {
+ case MMC5983_REG_CTRL0:
+ case MMC5983_REG_CTRL1:
+ case MMC5983_REG_CTRL2:
+ case MMC5983_REG_CTRL3:
+ return true;
+ default:
+ return false;
+ }
+}
+
+static bool mmc5983_is_readable_reg(struct device *dev, unsigned int reg)
+{
+ switch (reg) {
+ case MMC5983_REG_XOUT0:
+ case MMC5983_REG_XOUT1:
+ case MMC5983_REG_YOUT0:
+ case MMC5983_REG_YOUT1:
+ case MMC5983_REG_ZOUT0:
+ case MMC5983_REG_ZOUT1:
+ case MMC5983_REG_XYZOUT2:
+ case MMC5983_REG_STATUS:
+ case MMC5983_REG_CTRL0:
+ case MMC5983_REG_CTRL1:
+ case MMC5983_REG_CTRL2:
+ case MMC5983_REG_CTRL3:
+ case MMC5983_REG_ID:
+ return true;
+ default:
+ return false;
+ }
+}
+
+static bool mmc5983_is_volatile_reg(struct device *dev, unsigned int reg)
+{
+ switch (reg) {
+ case MMC5983_REG_XOUT0:
+ case MMC5983_REG_XOUT1:
+ case MMC5983_REG_YOUT0:
+ case MMC5983_REG_YOUT1:
+ case MMC5983_REG_ZOUT0:
+ case MMC5983_REG_ZOUT1:
+ case MMC5983_REG_XYZOUT2:
+ case MMC5983_REG_STATUS:
+ case MMC5983_REG_CTRL0:
+ case MMC5983_REG_CTRL1:
+ return true;
+ default:
+ return false;
+ }
+}
+
+static const struct regmap_config mmc5983_regmap_config = {
+ .name = "mmc5983_regmap",
+ .reg_bits = 8,
+ .val_bits = 8,
+ .max_register = MMC5983_REG_ID,
+ .writeable_reg = mmc5983_is_writeable_reg,
+ .readable_reg = mmc5983_is_readable_reg,
+ .volatile_reg = mmc5983_is_volatile_reg,
+};
+
+static int mmc5983_init(struct mmc5983_data *data)
+{
+ struct regmap *regmap = data->regmap;
+ struct device *dev = regmap_get_device(regmap);
+ unsigned int reg_id, status;
+ int ret;
+
+ ret = regmap_read(regmap, MMC5983_REG_ID, ®_id);
+ if (ret)
+ return dev_err_probe(dev, ret, "Error reading product id\n");
+
+ if (reg_id != MMC5983_PRODUCT_ID)
+ dev_info(dev, "unexpected product id 0x%02x\n", reg_id);
+
+ ret = regmap_write(regmap, MMC5983_REG_CTRL1, MMC5983_CTRL1_SW_RST_BIT);
+ if (ret)
+ return ret;
+
+ /* Datasheet page 15: power-on time after SW_RST is 10 ms */
+ fsleep(10 * USEC_PER_MSEC);
+
+ ret = regmap_write(regmap, MMC5983_REG_CTRL0, MMC5983_CTRL0_OTP_RD_BIT);
+ if (ret)
+ return ret;
+
+ /*
+ * Datasheet page 15: OTP read completes and self-clears. No separate
+ * OTP refresh timeout is specified, so use the 10 ms power-on time as
+ * a conservative upper bound.
+ */
+ ret = regmap_read_poll_timeout(regmap, MMC5983_REG_STATUS, status,
+ status & MMC5983_STATUS_OTP_RD_DONE_BIT,
+ USEC_PER_MSEC,
+ 10 * USEC_PER_MSEC);
+ if (ret)
+ return ret;
+
+ /* SET: magnetize sensor elements in forward direction */
+ ret = mmc5983_pulse_coil(data, MMC5983_CTRL0_SET_BIT);
+ if (ret)
+ return ret;
+
+ /* RESET: magnetize sensor elements in reverse direction */
+ return mmc5983_pulse_coil(data, MMC5983_CTRL0_RESET_BIT);
+}
+
+static int mmc5983_probe(struct i2c_client *i2c)
+{
+ struct device *dev = &i2c->dev;
+ struct mmc5983_data *data;
+ struct iio_dev *indio_dev;
+ int ret;
+
+ indio_dev = devm_iio_device_alloc(dev, sizeof(*data));
+ if (!indio_dev)
+ return -ENOMEM;
+
+ data = iio_priv(indio_dev);
+
+ ret = devm_mutex_init(dev, &data->mutex);
+ if (ret)
+ return ret;
+
+ data->regmap = devm_regmap_init_i2c(i2c, &mmc5983_regmap_config);
+ if (IS_ERR(data->regmap))
+ return dev_err_probe(dev, PTR_ERR(data->regmap),
+ "failed to allocate register map\n");
+
+ indio_dev->info = &mmc5983_info;
+ indio_dev->modes = INDIO_DIRECT_MODE;
+ indio_dev->name = "mmc5983";
+ indio_dev->channels = mmc5983_channels;
+ indio_dev->num_channels = ARRAY_SIZE(mmc5983_channels);
+
+ ret = mmc5983_init(data);
+ if (ret)
+ return dev_err_probe(dev, ret, "mmc5983 chip init failed\n");
+
+ return devm_iio_device_register(dev, indio_dev);
+}
+
+static const struct of_device_id mmc5983_of_match[] = {
+ { .compatible = "memsic,mmc5983" },
+ { }
+};
+MODULE_DEVICE_TABLE(of, mmc5983_of_match);
+
+static const struct i2c_device_id mmc5983_id[] = {
+ { "mmc5983" },
+ { }
+};
+MODULE_DEVICE_TABLE(i2c, mmc5983_id);
+
+static struct i2c_driver mmc5983_driver = {
+ .driver = {
+ .name = "mmc5983",
+ .of_match_table = mmc5983_of_match,
+ },
+ .probe = mmc5983_probe,
+ .id_table = mmc5983_id,
+};
+module_i2c_driver(mmc5983_driver);
+
+MODULE_AUTHOR("Vladislav Kulikov <vlad.kulikov.c@gmail.com>");
+MODULE_DESCRIPTION("MEMSIC MMC5983 magnetic sensor driver");
+MODULE_LICENSE("GPL");
projects / thirdparty / linux.git / commitdiff
