iio: health: add MAX30102 oximeter driver support

MAX30102 is an heart rate and pulse oximeter sensor that works using
two LEDS of different wavelengths, and detecting the light reflected
back.

This patchset adds support for both IR and RED LED channels which can
be processed in userspace to determine heart rate and blood oxygen
levels. The MAX30102 part isn't completely register and functional
compatible with the existing MAX30100 driver.

Signed-off-by: Matt Ranostay <matt@ranostay.consulting>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>

3 files changed, 499 insertions, 0 deletions

diff --git a/drivers/iio/health/Kconfig b/drivers/iio/health/Kconfig
index c5f004a8e447..a2ecb4c94c2a 100644
--- a/drivers/iio/health/Kconfig
+++ b/drivers/iio/health/Kconfig
@@ -46,6 +46,19 @@ config MAX30100
 	  To compile this driver as a module, choose M here: the
 	  module will be called max30100.
 
+config MAX30102
+	tristate "MAX30102 heart rate and pulse oximeter sensor"
+	depends on I2C
+	select REGMAP_I2C
+	select IIO_BUFFER
+	select IIO_KFIFO_BUF
+	help
+	  Say Y here to build I2C interface support for the Maxim
+	  MAX30102 heart rate, and pulse oximeter sensor.
+
+	  To compile this driver as a module, choose M here: the
+	  module will be called max30102.
+
 endmenu
 
 endmenu
diff --git a/drivers/iio/health/Makefile b/drivers/iio/health/Makefile
index 9955a2ae8df1..3558f9d64954 100644
--- a/drivers/iio/health/Makefile
+++ b/drivers/iio/health/Makefile
@@ -7,3 +7,4 @@
 obj-$(CONFIG_AFE4403)		+= afe4403.o
 obj-$(CONFIG_AFE4404)		+= afe4404.o
 obj-$(CONFIG_MAX30100)		+= max30100.o
+obj-$(CONFIG_MAX30102)		+= max30102.o
diff --git a/drivers/iio/health/max30102.c b/drivers/iio/health/max30102.c
new file mode 100644
index 000000000000..377518c15552
--- /dev/null
+++ b/drivers/iio/health/max30102.c
@@ -0,0 +1,485 @@
+/*
+ * max30102.c - Support for MAX30102 heart rate and pulse oximeter sensor
+ *
+ * Copyright (C) 2017 Matt Ranostay <matt@ranostay.consulting>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * TODO: proximity power saving feature
+ */
+
+#include <linux/module.h>
+#include <linux/init.h>
+#include <linux/interrupt.h>
+#include <linux/delay.h>
+#include <linux/err.h>
+#include <linux/irq.h>
+#include <linux/i2c.h>
+#include <linux/mutex.h>
+#include <linux/of.h>
+#include <linux/regmap.h>
+#include <linux/iio/iio.h>
+#include <linux/iio/buffer.h>
+#include <linux/iio/kfifo_buf.h>
+
+#define MAX30102_REGMAP_NAME	"max30102_regmap"
+#define MAX30102_DRV_NAME	"max30102"
+
+#define MAX30102_REG_INT_STATUS			0x00
+#define MAX30102_REG_INT_STATUS_PWR_RDY		BIT(0)
+#define MAX30102_REG_INT_STATUS_PROX_INT	BIT(4)
+#define MAX30102_REG_INT_STATUS_ALC_OVF		BIT(5)
+#define MAX30102_REG_INT_STATUS_PPG_RDY		BIT(6)
+#define MAX30102_REG_INT_STATUS_FIFO_RDY	BIT(7)
+
+#define MAX30102_REG_INT_ENABLE			0x02
+#define MAX30102_REG_INT_ENABLE_PROX_INT_EN	BIT(4)
+#define MAX30102_REG_INT_ENABLE_ALC_OVF_EN	BIT(5)
+#define MAX30102_REG_INT_ENABLE_PPG_EN		BIT(6)
+#define MAX30102_REG_INT_ENABLE_FIFO_EN		BIT(7)
+#define MAX30102_REG_INT_ENABLE_MASK		0xf0
+#define MAX30102_REG_INT_ENABLE_MASK_SHIFT	4
+
+#define MAX30102_REG_FIFO_WR_PTR		0x04
+#define MAX30102_REG_FIFO_OVR_CTR		0x05
+#define MAX30102_REG_FIFO_RD_PTR		0x06
+#define MAX30102_REG_FIFO_DATA			0x07
+#define MAX30102_REG_FIFO_DATA_ENTRY_LEN	6
+
+#define MAX30102_REG_FIFO_CONFIG		0x08
+#define MAX30102_REG_FIFO_CONFIG_AVG_4SAMPLES	BIT(1)
+#define MAX30102_REG_FIFO_CONFIG_AVG_SHIFT	5
+#define MAX30102_REG_FIFO_CONFIG_AFULL		BIT(0)
+
+#define MAX30102_REG_MODE_CONFIG		0x09
+#define MAX30102_REG_MODE_CONFIG_MODE_SPO2_EN	BIT(0)
+#define MAX30102_REG_MODE_CONFIG_MODE_HR_EN	BIT(1)
+#define MAX30102_REG_MODE_CONFIG_MODE_MASK	0x03
+#define MAX30102_REG_MODE_CONFIG_PWR		BIT(7)
+
+#define MAX30102_REG_SPO2_CONFIG		0x0a
+#define MAX30102_REG_SPO2_CONFIG_PULSE_411_US	0x03
+#define MAX30102_REG_SPO2_CONFIG_SR_400HZ	0x03
+#define MAX30102_REG_SPO2_CONFIG_SR_MASK	0x07
+#define MAX30102_REG_SPO2_CONFIG_SR_MASK_SHIFT	2
+#define MAX30102_REG_SPO2_CONFIG_ADC_4096_STEPS	BIT(0)
+#define MAX30102_REG_SPO2_CONFIG_ADC_MASK_SHIFT	5
+
+#define MAX30102_REG_RED_LED_CONFIG		0x0c
+#define MAX30102_REG_IR_LED_CONFIG		0x0d
+
+#define MAX30102_REG_TEMP_CONFIG		0x21
+#define MAX30102_REG_TEMP_CONFIG_TEMP_EN	BIT(0)
+
+#define MAX30102_REG_TEMP_INTEGER		0x1f
+#define MAX30102_REG_TEMP_FRACTION		0x20
+
+struct max30102_data {
+	struct i2c_client *client;
+	struct iio_dev *indio_dev;
+	struct mutex lock;
+	struct regmap *regmap;
+
+	u8 buffer[8];
+	__be32 processed_buffer[2]; /* 2 x 18-bit (padded to 32-bits) */
+};
+
+static const struct regmap_config max30102_regmap_config = {
+	.name = MAX30102_REGMAP_NAME,
+
+	.reg_bits = 8,
+	.val_bits = 8,
+};
+
+static const unsigned long max30102_scan_masks[] = {0x3, 0};
+
+static const struct iio_chan_spec max30102_channels[] = {
+	{
+		.type = IIO_INTENSITY,
+		.channel2 = IIO_MOD_LIGHT_RED,
+		.modified = 1,
+
+		.scan_index = 0,
+		.scan_type = {
+			.sign = 'u',
+			.shift = 8,
+			.realbits = 18,
+			.storagebits = 32,
+			.endianness = IIO_BE,
+		},
+	},
+	{
+		.type = IIO_INTENSITY,
+		.channel2 = IIO_MOD_LIGHT_IR,
+		.modified = 1,
+
+		.scan_index = 1,
+		.scan_type = {
+			.sign = 'u',
+			.shift = 8,
+			.realbits = 18,
+			.storagebits = 32,
+			.endianness = IIO_BE,
+		},
+	},
+	{
+		.type = IIO_TEMP,
+		.info_mask_separate =
+			BIT(IIO_CHAN_INFO_RAW) | BIT(IIO_CHAN_INFO_SCALE),
+		.scan_index = -1,
+	},
+};
+
+static int max30102_set_powermode(struct max30102_data *data, bool state)
+{
+	return regmap_update_bits(data->regmap, MAX30102_REG_MODE_CONFIG,
+				  MAX30102_REG_MODE_CONFIG_PWR,
+				  state ? 0 : MAX30102_REG_MODE_CONFIG_PWR);
+}
+
+static int max30102_buffer_postenable(struct iio_dev *indio_dev)
+{
+	struct max30102_data *data = iio_priv(indio_dev);
+
+	return max30102_set_powermode(data, true);
+}
+
+static int max30102_buffer_predisable(struct iio_dev *indio_dev)
+{
+	struct max30102_data *data = iio_priv(indio_dev);
+
+	return max30102_set_powermode(data, false);
+}
+
+static const struct iio_buffer_setup_ops max30102_buffer_setup_ops = {
+	.postenable = max30102_buffer_postenable,
+	.predisable = max30102_buffer_predisable,
+};
+
+static inline int max30102_fifo_count(struct max30102_data *data)
+{
+	unsigned int val;
+	int ret;
+
+	ret = regmap_read(data->regmap, MAX30102_REG_INT_STATUS, &val);
+	if (ret)
+		return ret;
+
+	/* FIFO has one sample slot left */
+	if (val & MAX30102_REG_INT_STATUS_FIFO_RDY)
+		return 1;
+
+	return 0;
+}
+
+static int max30102_read_measurement(struct max30102_data *data)
+{
+	int ret;
+	u8 *buffer = (u8 *) &data->buffer;
+
+	ret = i2c_smbus_read_i2c_block_data(data->client,
+					    MAX30102_REG_FIFO_DATA,
+					    MAX30102_REG_FIFO_DATA_ENTRY_LEN,
+					    buffer);
+
+	memcpy(&data->processed_buffer[0], &buffer[0], 3);
+	memcpy(&data->processed_buffer[1], &buffer[3], 3);
+
+	return (ret == MAX30102_REG_FIFO_DATA_ENTRY_LEN) ? 0 : -EINVAL;
+}
+
+static irqreturn_t max30102_interrupt_handler(int irq, void *private)
+{
+	struct iio_dev *indio_dev = private;
+	struct max30102_data *data = iio_priv(indio_dev);
+	int ret, cnt = 0;
+
+	mutex_lock(&data->lock);
+
+	while (cnt || (cnt = max30102_fifo_count(data)) > 0) {
+		ret = max30102_read_measurement(data);
+		if (ret)
+			break;
+
+		iio_push_to_buffers(data->indio_dev, data->processed_buffer);
+		cnt--;
+	}
+
+	mutex_unlock(&data->lock);
+
+	return IRQ_HANDLED;
+}
+
+static int max30102_get_current_idx(unsigned int val, int *reg)
+{
+	/* each step is 0.200 mA */
+	*reg = val / 200;
+
+	return *reg > 0xff ? -EINVAL : 0;
+}
+
+static int max30102_led_init(struct max30102_data *data)
+{
+	struct device *dev = &data->client->dev;
+	struct device_node *np = dev->of_node;
+	unsigned int val;
+	int reg, ret;
+
+	ret = of_property_read_u32(np, "maxim,red-led-current-microamp", &val);
+	if (ret) {
+		dev_info(dev, "no red-led-current-microamp set\n");
+
+		/* Default to 7 mA RED LED */
+		val = 7000;
+	}
+
+	ret = max30102_get_current_idx(val, &reg);
+	if (ret) {
+		dev_err(dev, "invalid RED LED current setting %d\n", val);
+		return ret;
+	}
+
+	ret = regmap_write(data->regmap, MAX30102_REG_RED_LED_CONFIG, reg);
+	if (ret)
+		return ret;
+
+	ret = of_property_read_u32(np, "maxim,ir-led-current-microamp", &val);
+	if (ret) {
+		dev_info(dev, "no ir-led-current-microamp set\n");
+
+		/* Default to 7 mA IR LED */
+		val = 7000;
+	}
+
+	ret = max30102_get_current_idx(val, &reg);
+	if (ret) {
+		dev_err(dev, "invalid IR LED current setting %d", val);
+		return ret;
+	}
+
+	return regmap_write(data->regmap, MAX30102_REG_IR_LED_CONFIG, reg);
+}
+
+static int max30102_chip_init(struct max30102_data *data)
+{
+	int ret;
+
+	/* setup LED current settings */
+	ret = max30102_led_init(data);
+	if (ret)
+		return ret;
+
+	/* enable 18-bit HR + SPO2 readings at 400Hz */
+	ret = regmap_write(data->regmap, MAX30102_REG_SPO2_CONFIG,
+				(MAX30102_REG_SPO2_CONFIG_ADC_4096_STEPS
+				 << MAX30102_REG_SPO2_CONFIG_ADC_MASK_SHIFT) |
+				(MAX30102_REG_SPO2_CONFIG_SR_400HZ
+				 << MAX30102_REG_SPO2_CONFIG_SR_MASK_SHIFT) |
+				 MAX30102_REG_SPO2_CONFIG_PULSE_411_US);
+	if (ret)
+		return ret;
+
+	/* enable SPO2 mode */
+	ret = regmap_update_bits(data->regmap, MAX30102_REG_MODE_CONFIG,
+				 MAX30102_REG_MODE_CONFIG_MODE_MASK,
+				 MAX30102_REG_MODE_CONFIG_MODE_HR_EN |
+				 MAX30102_REG_MODE_CONFIG_MODE_SPO2_EN);
+	if (ret)
+		return ret;
+
+	/* average 4 samples + generate FIFO interrupt */
+	ret = regmap_write(data->regmap, MAX30102_REG_FIFO_CONFIG,
+				(MAX30102_REG_FIFO_CONFIG_AVG_4SAMPLES
+				 << MAX30102_REG_FIFO_CONFIG_AVG_SHIFT) |
+				 MAX30102_REG_FIFO_CONFIG_AFULL);
+	if (ret)
+		return ret;
+
+	/* enable FIFO interrupt */
+	return regmap_update_bits(data->regmap, MAX30102_REG_INT_ENABLE,
+				 MAX30102_REG_INT_ENABLE_MASK,
+				 MAX30102_REG_INT_ENABLE_FIFO_EN);
+}
+
+static int max30102_read_temp(struct max30102_data *data, int *val)
+{
+	int ret;
+	unsigned int reg;
+
+	ret = regmap_read(data->regmap, MAX30102_REG_TEMP_INTEGER, &reg);
+	if (ret < 0)
+		return ret;
+	*val = reg << 4;
+
+	ret = regmap_read(data->regmap, MAX30102_REG_TEMP_FRACTION, &reg);
+	if (ret < 0)
+		return ret;
+
+	*val |= reg & 0xf;
+	*val = sign_extend32(*val, 11);
+
+	return 0;
+}
+
+static int max30102_get_temp(struct max30102_data *data, int *val)
+{
+	int ret;
+
+	/* start acquisition */
+	ret = regmap_update_bits(data->regmap, MAX30102_REG_TEMP_CONFIG,
+				 MAX30102_REG_TEMP_CONFIG_TEMP_EN,
+				 MAX30102_REG_TEMP_CONFIG_TEMP_EN);
+	if (ret)
+		return ret;
+
+	msleep(35);
+
+	return max30102_read_temp(data, val);
+}
+
+static int max30102_read_raw(struct iio_dev *indio_dev,
+			     struct iio_chan_spec const *chan,
+			     int *val, int *val2, long mask)
+{
+	struct max30102_data *data = iio_priv(indio_dev);
+	int ret = -EINVAL;
+
+	switch (mask) {
+	case IIO_CHAN_INFO_RAW:
+		/*
+		 * Temperature reading can only be acquired while engine
+		 * is running
+		 */
+		mutex_lock(&indio_dev->mlock);
+
+		if (!iio_buffer_enabled(indio_dev))
+			ret = -EBUSY;
+		else {
+			ret = max30102_get_temp(data, val);
+			if (!ret)
+				ret = IIO_VAL_INT;
+		}
+
+		mutex_unlock(&indio_dev->mlock);
+		break;
+	case IIO_CHAN_INFO_SCALE:
+		*val = 1;  /* 0.0625 */
+		*val2 = 16;
+		ret = IIO_VAL_FRACTIONAL;
+		break;
+	}
+
+	return ret;
+}
+
+static const struct iio_info max30102_info = {
+	.driver_module = THIS_MODULE,
+	.read_raw = max30102_read_raw,
+};
+
+static int max30102_probe(struct i2c_client *client,
+			  const struct i2c_device_id *id)
+{
+	struct max30102_data *data;
+	struct iio_buffer *buffer;
+	struct iio_dev *indio_dev;
+	int ret;
+
+	indio_dev = devm_iio_device_alloc(&client->dev, sizeof(*data));
+	if (!indio_dev)
+		return -ENOMEM;
+
+	buffer = devm_iio_kfifo_allocate(&client->dev);
+	if (!buffer)
+		return -ENOMEM;
+
+	iio_device_attach_buffer(indio_dev, buffer);
+
+	indio_dev->name = MAX30102_DRV_NAME;
+	indio_dev->channels = max30102_channels;
+	indio_dev->info = &max30102_info;
+	indio_dev->num_channels = ARRAY_SIZE(max30102_channels);
+	indio_dev->available_scan_masks = max30102_scan_masks;
+	indio_dev->modes = (INDIO_BUFFER_SOFTWARE | INDIO_DIRECT_MODE);
+	indio_dev->setup_ops = &max30102_buffer_setup_ops;
+
+	data = iio_priv(indio_dev);
+	data->indio_dev = indio_dev;
+	data->client = client;
+
+	mutex_init(&data->lock);
+	i2c_set_clientdata(client, indio_dev);
+
+	data->regmap = devm_regmap_init_i2c(client, &max30102_regmap_config);
+	if (IS_ERR(data->regmap)) {
+		dev_err(&client->dev, "regmap initialization failed.\n");
+		return PTR_ERR(data->regmap);
+	}
+	max30102_set_powermode(data, false);
+
+	ret = max30102_chip_init(data);
+	if (ret)
+		return ret;
+
+	if (client->irq <= 0) {
+		dev_err(&client->dev, "no valid irq defined\n");
+		return -EINVAL;
+	}
+
+	ret = devm_request_threaded_irq(&client->dev, client->irq,
+					NULL, max30102_interrupt_handler,
+					IRQF_TRIGGER_FALLING | IRQF_ONESHOT,
+					"max30102_irq", indio_dev);
+	if (ret) {
+		dev_err(&client->dev, "request irq (%d) failed\n", client->irq);
+		return ret;
+	}
+
+	return iio_device_register(indio_dev);
+}
+
+static int max30102_remove(struct i2c_client *client)
+{
+	struct iio_dev *indio_dev = i2c_get_clientdata(client);
+	struct max30102_data *data = iio_priv(indio_dev);
+
+	iio_device_unregister(indio_dev);
+	max30102_set_powermode(data, false);
+
+	return 0;
+}
+
+static const struct i2c_device_id max30102_id[] = {
+	{ "max30102", 0 },
+	{}
+};
+MODULE_DEVICE_TABLE(i2c, max30102_id);
+
+static const struct of_device_id max30102_dt_ids[] = {
+	{ .compatible = "maxim,max30102" },
+	{ }
+};
+MODULE_DEVICE_TABLE(of, max30102_dt_ids);
+
+static struct i2c_driver max30102_driver = {
+	.driver = {
+		.name	= MAX30102_DRV_NAME,
+		.of_match_table	= of_match_ptr(max30102_dt_ids),
+	},
+	.probe		= max30102_probe,
+	.remove		= max30102_remove,
+	.id_table	= max30102_id,
+};
+module_i2c_driver(max30102_driver);
+
+MODULE_AUTHOR("Matt Ranostay <matt@ranostay.consulting>");
+MODULE_DESCRIPTION("MAX30102 heart rate and pulse oximeter sensor");
+MODULE_LICENSE("GPL");