Message-ID: <20241231132513.6944-3-apokusinski01@gmail.com>
Date: Tue, 31 Dec 2024 14:25:13 +0100
From: Antoni Pokusinski <apokusinski01@...il.com>
To: jic23@...nel.org,
	krzysztof.kozlowski@...aro.org,
	lars@...afoo.de,
	robh@...nel.org,
	conor+dt@...nel.org,
	andrej.skvortzov@...il.com,
	neil.armstrong@...aro.org,
	danila@...xyga.com,
	icenowy@...c.io,
	javier.carrasco.cruz@...il.com,
	andy@...nel.org,
	megi@....cz
Cc: linux-iio@...r.kernel.org,
	devicetree@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	Antoni Pokusinski <apokusinski01@...il.com>
Subject: [PATCH 2/2] iio: magnetometer: si7210: add driver for Si7210

Silicon Labs Si7210 is an I2C Hall effect magnetic position and
temperature sensor. The driver supports the following functionalities:
* reading the temperature measurements
* reading the magnetic field measurements in a single-shot mode
* choosing the magnetic field measurement scale (20 or 200 mT)

Signed-off-by: Antoni Pokusinski <apokusinski01@...il.com>
---
 drivers/iio/magnetometer/Kconfig  |  11 +
 drivers/iio/magnetometer/Makefile |   2 +
 drivers/iio/magnetometer/si7210.c | 412 ++++++++++++++++++++++++++++++
 3 files changed, 425 insertions(+)
 create mode 100644 drivers/iio/magnetometer/si7210.c

diff --git a/drivers/iio/magnetometer/Kconfig b/drivers/iio/magnetometer/Kconfig
index 7177cd1d67cb..3debf1320ad1 100644
--- a/drivers/iio/magnetometer/Kconfig
+++ b/drivers/iio/magnetometer/Kconfig
@@ -235,6 +235,17 @@ config SENSORS_RM3100_SPI
 	  To compile this driver as a module, choose M here: the module
 	  will be called rm3100-spi.
 
+config SI7210
+	tristate "SI7210 Hall effect sensor"
+	depends on I2C
+	select REGMAP_I2C
+	help
+	  Say Y here to add support for the SI7210 Hall effect sensor.
+
+	  This driver can also be compiled as a module.
+	  To compile this driver as a module, choose M here: the module
+	  will be called si7210.
+
 config TI_TMAG5273
 	tristate "TI TMAG5273 Low-Power Linear 3D Hall-Effect Sensor"
 	depends on I2C
diff --git a/drivers/iio/magnetometer/Makefile b/drivers/iio/magnetometer/Makefile
index 3e4c2ecd9adf..58f32a855494 100644
--- a/drivers/iio/magnetometer/Makefile
+++ b/drivers/iio/magnetometer/Makefile
@@ -31,6 +31,8 @@ obj-$(CONFIG_SENSORS_RM3100)		+= rm3100-core.o
 obj-$(CONFIG_SENSORS_RM3100_I2C)	+= rm3100-i2c.o
 obj-$(CONFIG_SENSORS_RM3100_SPI)	+= rm3100-spi.o
 
+obj-$(CONFIG_SI7210) += si7210.o
+
 obj-$(CONFIG_TI_TMAG5273)		+= tmag5273.o
 
 obj-$(CONFIG_YAMAHA_YAS530)		+= yamaha-yas530.o
diff --git a/drivers/iio/magnetometer/si7210.c b/drivers/iio/magnetometer/si7210.c
new file mode 100644
index 000000000000..3b9b5b9807fd
--- /dev/null
+++ b/drivers/iio/magnetometer/si7210.c
@@ -0,0 +1,412 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Silicon Labs Si7210 Hall Effect sensor driver
+ *
+ * Copyright (c) 2024 Antoni Pokusinski <apokusinski01@...il.com>
+ *
+ * Datasheet:
+ *  https://www.silabs.com/documents/public/data-sheets/si7210-datasheet.pdf
+ */
+
+#include <linux/module.h>
+#include <linux/i2c.h>
+#include <linux/iio/iio.h>
+#include <linux/regmap.h>
+#include <linux/math64.h>
+#include <linux/mutex.h>
+
+/* Registers offsets and masks */
+#define SI7210_REG_DSPSIGM	0xC1
+#define SI7210_REG_DSPSIGL	0xC2
+
+#define SI7210_MASK_DSPSIGSEL	GENMASK(2, 0)
+#define SI7210_REG_DSPSIGSEL	0xC3
+
+#define SI7210_MASK_STOP	BIT(1)
+#define SI7210_MASK_ONEBURST	BIT(2)
+#define SI7210_REG_POWER_CTRL	0xC4
+
+#define SI7210_MASK_ARAUTOINC	BIT(0)
+#define SI7210_REG_ARAUTOINC	0xC5
+
+#define SI7210_REG_A0		0xCA
+#define SI7210_REG_A1		0xCB
+#define SI7210_REG_A2		0xCC
+#define SI7210_REG_A3		0xCE
+#define SI7210_REG_A4		0xCF
+#define SI7210_REG_A5		0xD0
+
+#define SI7210_REG_OTP_ADDR	0xE1
+#define SI7210_REG_OTP_DATA	0xE2
+
+#define SI7210_MASK_OTP_READ_EN	BIT(1)
+#define SI7210_REG_OTP_CTRL	0xE3
+
+/* OTP data registers offsets */
+#define SI7210_OTPREG_TMP_OFF	0x1D
+#define SI7210_OTPREG_TMP_GAIN	0x1E
+
+#define SI7210_OTPREG_A0_20	0x21
+#define SI7210_OTPREG_A1_20	0x22
+#define SI7210_OTPREG_A2_20	0x23
+#define SI7210_OTPREG_A3_20	0x24
+#define SI7210_OTPREG_A4_20	0x25
+#define SI7210_OTPREG_A5_20	0x26
+
+#define SI7210_OTPREG_A0_200	0x27
+#define SI7210_OTPREG_A1_200	0x28
+#define SI7210_OTPREG_A2_200	0x29
+#define SI7210_OTPREG_A3_200	0x2A
+#define SI7210_OTPREG_A4_200	0x2B
+#define SI7210_OTPREG_A5_200	0x2C
+
+#define A_REGS_COUNT 6
+
+static const unsigned int a20_otp_regs[A_REGS_COUNT] = {
+	SI7210_OTPREG_A0_20, SI7210_OTPREG_A1_20, SI7210_OTPREG_A2_20,
+	SI7210_OTPREG_A3_20, SI7210_OTPREG_A4_20, SI7210_OTPREG_A5_20
+};
+
+static const unsigned int a200_otp_regs[A_REGS_COUNT] = {
+	SI7210_OTPREG_A0_200, SI7210_OTPREG_A1_200, SI7210_OTPREG_A2_200,
+	SI7210_OTPREG_A3_200, SI7210_OTPREG_A4_200, SI7210_OTPREG_A5_200
+};
+
+static const struct regmap_range si7210_read_reg_ranges[] = {
+	regmap_reg_range(SI7210_REG_DSPSIGM, SI7210_REG_ARAUTOINC),
+	regmap_reg_range(SI7210_REG_A0, SI7210_REG_A2),
+	regmap_reg_range(SI7210_REG_A3, SI7210_REG_A5),
+	regmap_reg_range(SI7210_REG_OTP_ADDR, SI7210_REG_OTP_CTRL),
+};
+
+static const struct regmap_access_table si7210_readable_regs = {
+	.yes_ranges = si7210_read_reg_ranges,
+	.n_yes_ranges = ARRAY_SIZE(si7210_read_reg_ranges),
+};
+
+static const struct regmap_range si7210_write_reg_ranges[] = {
+	regmap_reg_range(SI7210_REG_DSPSIGSEL, SI7210_REG_ARAUTOINC),
+	regmap_reg_range(SI7210_REG_A0, SI7210_REG_A2),
+	regmap_reg_range(SI7210_REG_A3, SI7210_REG_A5),
+	regmap_reg_range(SI7210_REG_OTP_ADDR, SI7210_REG_OTP_CTRL),
+};
+
+static const struct regmap_access_table si7210_writeable_regs = {
+	.yes_ranges = si7210_write_reg_ranges,
+	.n_yes_ranges = ARRAY_SIZE(si7210_write_reg_ranges),
+};
+
+static const struct regmap_range si7210_volatile_reg_ranges[] = {
+	regmap_reg_range(SI7210_REG_DSPSIGM, SI7210_REG_DSPSIGL),
+	regmap_reg_range(SI7210_REG_POWER_CTRL, SI7210_REG_POWER_CTRL),
+};
+
+static const struct regmap_access_table si7210_volatile_regs = {
+	.yes_ranges = si7210_volatile_reg_ranges,
+	.n_yes_ranges = ARRAY_SIZE(si7210_volatile_reg_ranges),
+};
+
+static const struct regmap_config si7210_regmap_conf = {
+	.reg_bits = 8,
+	.val_bits = 8,
+	.max_register = SI7210_REG_OTP_CTRL,
+
+	.rd_table = &si7210_readable_regs,
+	.wr_table = &si7210_writeable_regs,
+	.volatile_table = &si7210_volatile_regs,
+};
+
+struct si7210_data {
+	struct i2c_client *client;
+	struct regmap *regmap;
+	struct mutex fetch_lock;
+	struct mutex otp_lock;
+	s8 temp_offset;
+	s8 temp_gain;
+	s8 scale_20_a[A_REGS_COUNT];
+	s8 scale_200_a[A_REGS_COUNT];
+	u8 curr_scale;
+};
+
+static const struct iio_chan_spec si7210_channels[] = {
+	{
+		.type = IIO_MAGN,
+		.info_mask_separate = BIT(IIO_CHAN_INFO_RAW) |
+			BIT(IIO_CHAN_INFO_SCALE) | BIT(IIO_CHAN_INFO_OFFSET),
+	},
+	{
+		.type = IIO_TEMP,
+		.info_mask_separate = BIT(IIO_CHAN_INFO_PROCESSED),
+	}
+};
+
+static int si7210_fetch_measurement(struct si7210_data *data,
+				    struct iio_chan_spec const *chan,
+				    u8 buf[2])
+{
+	u8 dspsigsel = chan->type == IIO_MAGN ? 0 : 1;
+	int ret;
+
+	scoped_guard(mutex, &data->fetch_lock) {
+		ret = regmap_update_bits(data->regmap, SI7210_REG_DSPSIGSEL,
+					 SI7210_MASK_DSPSIGSEL, dspsigsel);
+		if (ret < 0)
+			return ret;
+
+		ret = regmap_update_bits(data->regmap, SI7210_REG_POWER_CTRL,
+					 SI7210_MASK_ONEBURST | SI7210_MASK_STOP,
+					 SI7210_MASK_ONEBURST & ~SI7210_MASK_STOP);
+		if (ret < 0)
+			return ret;
+
+		/* Read the contents of the registers containing the result: DSPSIGM, DSPSIGL */
+		ret = regmap_bulk_read(data->regmap, SI7210_REG_DSPSIGM, buf, 2);
+		if (ret < 0)
+			return ret;
+	}
+
+	return 0;
+}
+
+static int si7210_read_raw(struct iio_dev *indio_dev,
+			   struct iio_chan_spec const *chan,
+			   int *val, int *val2, long mask)
+{
+	struct si7210_data *data = iio_priv(indio_dev);
+	long long tmp;
+	u8 dspsig[2];
+	int ret;
+
+	switch (mask) {
+	case IIO_CHAN_INFO_RAW:
+		ret = si7210_fetch_measurement(data, chan, dspsig);
+		if (ret < 0)
+			return ret;
+
+		*val = ((dspsig[0] & 0x7F) << 8) + dspsig[1];
+		return IIO_VAL_INT;
+	case IIO_CHAN_INFO_SCALE:
+		*val = 0;
+		if (data->curr_scale == 20)
+			*val2 = 1250;
+		else /* data->curr_scale == 200 */
+			*val2 = 12500;
+		return IIO_VAL_INT_PLUS_MICRO;
+	case IIO_CHAN_INFO_OFFSET:
+		*val = -16384;
+		return IIO_VAL_INT;
+	case IIO_CHAN_INFO_PROCESSED:
+		ret = si7210_fetch_measurement(data, chan, dspsig);
+		if (ret < 0)
+			return ret;
+
+		tmp = ((dspsig[0] & 0x7F) << 5) + (dspsig[1] >> 3);
+		tmp = (div_s64(-383 * tmp * tmp, 100) + (160940 * tmp - 279800000));
+		tmp = (1 + (data->temp_gain >> 11)) * tmp + 62500 * data->temp_offset;
+		tmp -= 732600;
+
+		*val = div_s64_rem(tmp, 1000000, val2);
+
+		return IIO_VAL_INT_PLUS_MICRO;
+	default:
+		return -EINVAL;
+	}
+}
+
+static int si7210_set_scale(struct si7210_data *data, unsigned int scale)
+{
+	s8 *a_otp_values;
+	int ret;
+
+	if (scale == 20)
+		a_otp_values = data->scale_20_a;
+	else if (scale == 200)
+		a_otp_values = data->scale_200_a;
+	else
+		return -EINVAL;
+
+	scoped_guard(mutex, &data->fetch_lock) {
+		/* Write the registers 0xCA - 0xCC*/
+		ret = regmap_bulk_write(data->regmap, SI7210_REG_A0, a_otp_values, 3);
+		if (ret < 0)
+			return ret;
+
+		/* Write the registers 0xCE - 0xD0*/
+		ret = regmap_bulk_write(data->regmap, SI7210_REG_A3, &a_otp_values[3], 3);
+		if (ret < 0)
+			return ret;
+
+		data->curr_scale = scale;
+	}
+
+	return 0;
+}
+
+static int si7210_write_raw(struct iio_dev *indio_dev,
+			    struct iio_chan_spec const *chan,
+			    int val, int val2, long mask)
+{
+	struct si7210_data *data = iio_priv(indio_dev);
+	unsigned int scale;
+
+	switch (mask) {
+	case IIO_CHAN_INFO_SCALE:
+		if (val == 0 && val2 == 1250)
+			scale = 20;
+		else if (val == 0 && val2 == 12500)
+			scale = 200;
+		else
+			return -EINVAL;
+
+		return si7210_set_scale(data, scale);
+	default:
+		return -EINVAL;
+	}
+}
+
+static int si7210_read_otpreg_val(struct si7210_data *data, unsigned int otpreg, u8 *val)
+{
+	int ret;
+	unsigned int otpdata;
+
+	scoped_guard(mutex, &data->otp_lock) {
+		ret = regmap_write(data->regmap, SI7210_REG_OTP_ADDR, otpreg);
+		if (ret < 0)
+			return ret;
+
+		ret = regmap_update_bits(data->regmap, SI7210_REG_OTP_CTRL,
+					 SI7210_MASK_OTP_READ_EN, SI7210_MASK_OTP_READ_EN);
+		if (ret < 0)
+			return ret;
+
+		ret = regmap_read(data->regmap, SI7210_REG_OTP_DATA, &otpdata);
+		if (ret < 0)
+			return ret;
+
+		*val = (u8)otpdata;
+	}
+
+	return 0;
+}
+
+static int si7210_device_wake(struct si7210_data *data)
+{
+	/* According to the datasheet, the primary method to wake up a device is
+	 *  to send an empty write. However this is not feasible using current API so we
+	 *  use the other method i.e. read a single byte. The device should respond with 0xFF
+	 */
+
+	int ret = 0;
+
+	ret = i2c_smbus_read_byte(data->client);
+	if (ret < 0)
+		return ret;
+
+	if ((u8)ret != 0xFF)
+		return -EIO;
+
+	return 0;
+}
+
+static int si7210_device_init(struct si7210_data *data)
+{
+	int ret;
+	unsigned int i;
+
+	ret = si7210_device_wake(data);
+	if (ret < 0)
+		return ret;
+
+	usleep_range(1000, 1500);
+
+	ret = si7210_read_otpreg_val(data, SI7210_OTPREG_TMP_GAIN, &data->temp_gain);
+	if (ret < 0)
+		return ret;
+	ret = si7210_read_otpreg_val(data, SI7210_OTPREG_TMP_OFF, &data->temp_offset);
+	if (ret < 0)
+		return ret;
+
+	for (i = 0; i < A_REGS_COUNT; i++) {
+		ret = si7210_read_otpreg_val(data, a20_otp_regs[i], &data->scale_20_a[i]);
+		if (ret < 0)
+			return ret;
+	}
+	for (i = 0; i < A_REGS_COUNT; i++) {
+		ret = si7210_read_otpreg_val(data, a200_otp_regs[i], &data->scale_200_a[i]);
+		if (ret < 0)
+			return ret;
+	}
+
+	ret = regmap_update_bits(data->regmap, SI7210_REG_ARAUTOINC,
+				 SI7210_MASK_ARAUTOINC, SI7210_MASK_ARAUTOINC);
+	if (ret < 0)
+		return ret;
+
+	return si7210_set_scale(data, 20);
+}
+
+static const struct iio_info si7210_info = {
+	.read_raw = si7210_read_raw,
+	.write_raw = si7210_write_raw,
+};
+
+static int si7210_probe(struct i2c_client *client)
+{
+	struct si7210_data *data;
+	struct iio_dev *indio_dev;
+	int ret;
+
+	indio_dev = devm_iio_device_alloc(&client->dev, sizeof(*data));
+	if (!indio_dev)
+		return -ENOMEM;
+
+	data = iio_priv(indio_dev);
+	i2c_set_clientdata(client, indio_dev);
+	data->client = client;
+
+	mutex_init(&data->fetch_lock);
+	mutex_init(&data->otp_lock);
+
+	data->regmap = devm_regmap_init_i2c(client, &si7210_regmap_conf);
+	if (IS_ERR(data->regmap))
+		return dev_err_probe(&client->dev, PTR_ERR(data->regmap),
+				     "failed to register regmap\n");
+
+	indio_dev->name = dev_name(&client->dev);
+	indio_dev->modes = INDIO_DIRECT_MODE;
+	indio_dev->info = &si7210_info;
+	indio_dev->channels = si7210_channels;
+	indio_dev->num_channels = ARRAY_SIZE(si7210_channels);
+
+	ret = si7210_device_init(data);
+	if (ret)
+		return dev_err_probe(&client->dev, ret, "device initialization failed\n");
+
+	return devm_iio_device_register(&client->dev, indio_dev);
+}
+
+static const struct i2c_device_id si7210_id[] = {
+	{ "si7210", 0 },
+	{ }
+};
+MODULE_DEVICE_TABLE(i2c, si7210_id);
+
+static const struct of_device_id si7210_dt_ids[] = {
+	{ .compatible = "silabs,si7210" },
+	{ }
+};
+MODULE_DEVICE_TABLE(of, si7210_dt_ids);
+
+static struct i2c_driver si7210_driver = {
+	.driver = {
+		.name = "si7210",
+		.of_match_table = si7210_dt_ids,
+	},
+	.probe		= si7210_probe,
+	.id_table	= si7210_id,
+};
+
+module_i2c_driver(si7210_driver);
+MODULE_AUTHOR("Antoni Pokusinski <apokusinski01@...il.com>");
+MODULE_DESCRIPTION("Silicon Labs Si7210 Hall Effect sensor I2C driver");
+MODULE_LICENSE("Dual BSD/GPL");
-- 
2.45.2

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