Re: [PATCH v5 1/1] iio: light: add MAX30100 oximeter driver support

[Jonathan Cameron <jic23@kernel.org>]

On 04/12/15 05:15, Matt Ranostay wrote:
> MAX30100 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.
> 
> Signed-off-by: Matt Ranostay <mranostay@gmail.com>
A few little bits and bobs inline. Biggest one is how confused
I got with the fifo_is_empty function which definitely needs
some docs and renaming!

Nearly there :)

Jonathan
> ---
>  .../devicetree/bindings/iio/health/max30100.txt    |  21 +
>  drivers/iio/Kconfig                                |   1 +
>  drivers/iio/Makefile                               |   1 +
>  drivers/iio/health/Kconfig                         |  21 +
>  drivers/iio/health/Makefile                        |   7 +
>  drivers/iio/health/max30100.c                      | 457 +++++++++++++++++++++
>  6 files changed, 508 insertions(+)
>  create mode 100644 Documentation/devicetree/bindings/iio/health/max30100.txt
>  create mode 100644 drivers/iio/health/Kconfig
>  create mode 100644 drivers/iio/health/Makefile
>  create mode 100644 drivers/iio/health/max30100.c
> 
> diff --git a/Documentation/devicetree/bindings/iio/health/max30100.txt b/Documentation/devicetree/bindings/iio/health/max30100.txt
> new file mode 100644
> index 0000000..f6fbac6
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/iio/health/max30100.txt
> @@ -0,0 +1,21 @@
> +Maxim MAX30100 heart rate and pulse oximeter sensor
> +
> +* https://datasheets.maximintegrated.com/en/ds/MAX30100.pdf
> +
> +Required properties:
> +  - compatible: must be "maxim,max30100"
> +  - reg: the I2C address of the sensor
> +  - interrupt-parent: should be the phandle for the interrupt controller
> +  - interrupts: the sole interrupt generated by the device
> +
> +  Refer to interrupt-controller/interrupts.txt for generic
> +  interrupt client node bindings.
> +
> +Example:
> +
> +max30100@057 {
> +	compatible = "maxim,max30100";
> +	reg = <57>;
> +	interrupt-parent = <&gpio1>;
> +	interrupts = <16 2>;
> +};
> diff --git a/drivers/iio/Kconfig b/drivers/iio/Kconfig
> index 5dfb4f1..b846873 100644
> --- a/drivers/iio/Kconfig
> +++ b/drivers/iio/Kconfig
> @@ -68,6 +68,7 @@ source "drivers/iio/common/Kconfig"
>  source "drivers/iio/dac/Kconfig"
>  source "drivers/iio/frequency/Kconfig"
>  source "drivers/iio/gyro/Kconfig"
> +source "drivers/iio/health/Kconfig"
>  source "drivers/iio/humidity/Kconfig"
>  source "drivers/iio/imu/Kconfig"
>  source "drivers/iio/light/Kconfig"
> diff --git a/drivers/iio/Makefile b/drivers/iio/Makefile
> index dc73c1f..7371791 100644
> --- a/drivers/iio/Makefile
> +++ b/drivers/iio/Makefile
> @@ -20,6 +20,7 @@ obj-y += common/
>  obj-y += dac/
>  obj-y += gyro/
>  obj-y += frequency/
> +obj-y += health/
>  obj-y += humidity/
>  obj-y += imu/
>  obj-y += light/
> diff --git a/drivers/iio/health/Kconfig b/drivers/iio/health/Kconfig
> new file mode 100644
> index 0000000..a647679
> --- /dev/null
> +++ b/drivers/iio/health/Kconfig
> @@ -0,0 +1,21 @@
> +#
> +# Health sensors
> +#
> +# When adding new entries keep the list in alphabetical order
> +
> +menu "Health sensors"
> +
> +config MAX30100
> +	tristate "MAX30100 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
> +	  MAX30100 heart rate, and pulse oximeter sensor.
> +
> +	  To compile this driver as a module, choose M here: the
> +	  module will be called max30100.
> +
> +endmenu
> diff --git a/drivers/iio/health/Makefile b/drivers/iio/health/Makefile
> new file mode 100644
> index 0000000..7c475d7
> --- /dev/null
> +++ b/drivers/iio/health/Makefile
> @@ -0,0 +1,7 @@
> +#
> +# Makefile for IIO Health sensors
> +#
> +
> +# When adding new entries keep the list in alphabetical order
> +
> +obj-$(CONFIG_MAX30100)		+= max30100.o
> diff --git a/drivers/iio/health/max30100.c b/drivers/iio/health/max30100.c
> new file mode 100644
> index 0000000..1604315
> --- /dev/null
> +++ b/drivers/iio/health/max30100.c
> @@ -0,0 +1,457 @@
> +/*
> + * max30100.c - Support for MAX30100 heart rate and pulse oximeter sensor
> + *
> + * Copyright (C) 2015 Matt Ranostay <mranostay@gmail.com>
> + *
> + * 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: allow LED current and pulse length controls via device tree properties
> + */
> +
> +#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/regmap.h>
> +#include <linux/iio/iio.h>
> +#include <linux/iio/buffer.h>
> +#include <linux/iio/kfifo_buf.h>
> +
> +#define MAX30100_REGMAP_NAME	"max30100_regmap"
> +#define MAX30100_DRV_NAME	"max30100"
> +
> +#define MAX30100_REG_INT_STATUS			0x00
> +#define MAX30100_REG_INT_STATUS_PWR_RDY		BIT(0)
> +#define MAX30100_REG_INT_STATUS_SPO2_RDY	BIT(4)
> +#define MAX30100_REG_INT_STATUS_HR_RDY		BIT(5)
> +#define MAX30100_REG_INT_STATUS_FIFO_RDY	BIT(7)
> +
> +#define MAX30100_REG_INT_ENABLE			0x01
> +#define MAX30100_REG_INT_ENABLE_SPO2_EN		BIT(0)
> +#define MAX30100_REG_INT_ENABLE_HR_EN		BIT(1)
> +#define MAX30100_REG_INT_ENABLE_FIFO_EN		BIT(3)
> +#define MAX30100_REG_INT_ENABLE_MASK		0xf0
> +#define MAX30100_REG_INT_ENABLE_MASK_SHIFT	4
> +
> +#define MAX30100_REG_FIFO_WR_PTR		0x02
> +#define MAX30100_REG_FIFO_OVR_CTR		0x03
> +#define MAX30100_REG_FIFO_RD_PTR		0x04
> +#define MAX30100_REG_FIFO_DATA			0x05
> +#define MAX30100_REG_FIFO_DATA_ENTRY_LEN	4
> +
> +#define MAX30100_REG_MODE_CONFIG		0x06
> +#define MAX30100_REG_MODE_CONFIG_MODE_SPO2_EN	BIT(0)
> +#define MAX30100_REG_MODE_CONFIG_MODE_HR_EN	BIT(1)
> +#define MAX30100_REG_MODE_CONFIG_MODE_MASK	0x03
> +#define MAX30100_REG_MODE_CONFIG_TEMP_EN	BIT(3)
> +#define MAX30100_REG_MODE_CONFIG_PWR		BIT(7)
> +
> +#define MAX30100_REG_SPO2_CONFIG		0x07
> +#define MAX30100_REG_SPO2_CONFIG_HI_RES_EN	BIT(6)
> +
> +#define MAX30100_REG_SPO2_CONFIG_100HZ		BIT(2)
> +#define MAX30100_REG_SPO2_CONFIG_1600US		0x3
> +
> +#define MAX30100_REG_LED_CONFIG			0x09
> +#define MAX30100_REG_LED_CONFIG_RED_LED_SHIFT	4
> +
> +#define MAX30100_REG_LED_CONFIG_24MA		0x07
> +#define MAX30100_REG_LED_CONFIG_50MA		0x0f
> +
> +#define MAX30100_REG_TEMP_INTEGER		0x16
> +#define MAX30100_REG_TEMP_FRACTION		0x17
> +
> +struct max30100_data {
> +	struct i2c_client *client;
> +	struct iio_dev *indio_dev;
> +	struct mutex lock;
> +	struct regmap *regmap;
> +
> +	__be16 buffer[2]; /* 2 16-bit channels */
> +};
> +
> +static bool max30100_is_volatile_reg(struct device *dev, unsigned int reg)
> +{
> +	switch (reg) {
> +	case MAX30100_REG_INT_STATUS:
> +	case MAX30100_REG_MODE_CONFIG:
> +	case MAX30100_REG_FIFO_WR_PTR:
> +	case MAX30100_REG_FIFO_OVR_CTR:
> +	case MAX30100_REG_FIFO_RD_PTR:
> +	case MAX30100_REG_FIFO_DATA:
> +	case MAX30100_REG_TEMP_INTEGER:
> +	case MAX30100_REG_TEMP_FRACTION:
> +		return true;
> +	default:
> +		return false;
> +	}
> +}
> +
> +static const struct regmap_config max30100_regmap_config = {
> +	.name = MAX30100_REGMAP_NAME,
> +
> +	.reg_bits = 8,
> +	.val_bits = 8,
> +
> +	.max_register = MAX30100_REG_TEMP_FRACTION,
> +	.cache_type = REGCACHE_FLAT,
> +
> +	.volatile_reg = max30100_is_volatile_reg,
> +};
> +
> +static const unsigned long max30100_scan_masks[] = {0x3, 0};
> +
> +static const struct iio_chan_spec max30100_channels[] = {
> +	{
> +		.type = IIO_INTENSITY,
> +		.channel2 = IIO_MOD_LIGHT_IR,
> +		.modified = 1,
> +
> +		.scan_index = 0,
> +		.scan_type = {
> +			.sign = 'u',
> +			.realbits = 16,
> +			.storagebits = 16,
> +			.endianness = IIO_BE,
> +		},
> +	},
> +	{
> +		.type = IIO_INTENSITY,
> +		.channel2 = IIO_MOD_LIGHT_RED,
> +		.modified = 1,
> +
> +		.scan_index = 1,
> +		.scan_type = {
> +			.sign = 'u',
> +			.realbits = 16,
> +			.storagebits = 16,
> +			.endianness = IIO_BE,
> +		},
> +	},
> +	{
> +		.type = IIO_TEMP,
> +		.info_mask_separate =
> +			BIT(IIO_CHAN_INFO_RAW) | BIT(IIO_CHAN_INFO_SCALE),
> +		.scan_index = -1,
> +	},
> +};
> +
> +static int max30100_set_powermode(struct max30100_data *data, bool state)
> +{
> +	return regmap_update_bits(data->regmap, MAX30100_REG_MODE_CONFIG,
> +				  MAX30100_REG_MODE_CONFIG_PWR,
> +				  state ? 0 : MAX30100_REG_MODE_CONFIG_PWR);
> +}
> +
> +static int max30100_clear_fifo(struct max30100_data *data)
> +{
> +	int ret;
> +
> +	ret = regmap_write(data->regmap, MAX30100_REG_FIFO_WR_PTR, 0);
> +	if (ret)
> +		return ret;
> +
> +	ret = regmap_write(data->regmap, MAX30100_REG_FIFO_OVR_CTR, 0);
> +	if (ret)
> +		return ret;
> +
> +	return regmap_write(data->regmap, MAX30100_REG_FIFO_RD_PTR, 0);
> +}
> +
> +static int max30100_buffer_postenable(struct iio_dev *indio_dev)
> +{
> +	struct max30100_data *data = iio_priv(indio_dev);
> +	int ret;
> +
> +	ret = max30100_set_powermode(data, true);
> +	if (ret)
> +		return ret;
> +
> +	return max30100_clear_fifo(data);
> +}
> +
> +static int max30100_buffer_predisable(struct iio_dev *indio_dev)
> +{
> +	struct max30100_data *data = iio_priv(indio_dev);
> +
> +	return max30100_set_powermode(data, false);
> +}
> +
> +static const struct iio_buffer_setup_ops max30100_buffer_setup_ops = {
> +	.postenable = max30100_buffer_postenable,
> +	.predisable = max30100_buffer_predisable,
> +};
> +
> +static inline int max30100_fifo_is_empty(struct max30100_data *data)
As commented below, this function seems badly named.
> +{
> +	unsigned int val;
> +	int ret;
> +
> +	ret = regmap_read(data->regmap, MAX30100_REG_INT_STATUS, &val);
> +	if (ret)
> +		return ret;
> +
> +	if (val & MAX30100_REG_INT_STATUS_FIFO_RDY)
> +		return 15;
> +
> +	return !!(val >> 4);
Hmm. This needs comments as I had to datasheet dive to find out what
you are doing.

So this will be 1 if HR_RDY or SPO2_RDY are true (technically also the
temp ready but I don't think that is relevant here.)

What if only one of them is ready?  If that happens you want to wait until
they both are I think...
> +}
> +
> +static int max30100_read_measurement(struct max30100_data *data)
> +{
> +	int ret;
> +
> +	ret = i2c_smbus_read_i2c_block_data(data->client,
> +					    MAX30100_REG_FIFO_DATA,
> +					    MAX30100_REG_FIFO_DATA_ENTRY_LEN,
> +					    (u8 *) &data->buffer);
> +
> +	return (ret == MAX30100_REG_FIFO_DATA_ENTRY_LEN) ? 0 : ret;
> +}
> +
> +static irqreturn_t max30100_interrupt_handler(int irq, void *private)
> +{
> +	struct iio_dev *indio_dev = private;
> +	struct max30100_data *data = iio_priv(indio_dev);
> +	int ret, cnt = 0;
> +
> +	mutex_lock(&data->lock);
> +
> +	while (cnt-- || (cnt = max30100_fifo_is_empty(data) > 0)) {
This gave me a headache to figure out why this made sense...
The confusing bit is that max30100_fifo_is_empty doesn't return
that at all, but rather a 'known to be in fifo' count.

> +		ret = max30100_read_measurement(data);
> +		if (ret)
> +			break;
> +
> +		iio_push_to_buffers(data->indio_dev, data->buffer);
> +	}
> +
> +	mutex_unlock(&data->lock);
> +
> +	return IRQ_HANDLED;
> +}
> +
> +static int max30100_chip_init(struct max30100_data *data)
> +{
> +	int ret;
> +
> +	/* RED IR LED = 24mA, IR LED = 50mA */
> +	ret = regmap_write(data->regmap, MAX30100_REG_LED_CONFIG,
> +				(MAX30100_REG_LED_CONFIG_24MA <<
> +				 MAX30100_REG_LED_CONFIG_RED_LED_SHIFT) |
> +				 MAX30100_REG_LED_CONFIG_50MA);
> +	if (ret)
> +		return ret;
> +
> +	/* enable hi-res SPO2 readings with 100 samples a second */
> +	ret = regmap_write(data->regmap, MAX30100_REG_SPO2_CONFIG,
> +				 MAX30100_REG_SPO2_CONFIG_HI_RES_EN |
> +				 MAX30100_REG_SPO2_CONFIG_100HZ |
> +				 MAX30100_REG_SPO2_CONFIG_1600US);
> +	if (ret)
> +		return ret;
> +
> +	/* enable SPO2 mode */
> +	ret = regmap_update_bits(data->regmap, MAX30100_REG_MODE_CONFIG,
> +				 MAX30100_REG_MODE_CONFIG_MODE_MASK,
> +				 MAX30100_REG_MODE_CONFIG_MODE_HR_EN |
> +				 MAX30100_REG_MODE_CONFIG_MODE_SPO2_EN);
> +	if (ret)
> +		return ret;
> +
> +	/* enable SPO2 + FIFO interrupts */
> +	return regmap_update_bits(data->regmap, MAX30100_REG_INT_ENABLE,
> +				 MAX30100_REG_INT_ENABLE_MASK,
> +				(MAX30100_REG_INT_ENABLE_FIFO_EN |
> +				 MAX30100_REG_INT_ENABLE_SPO2_EN)
> +				 << MAX30100_REG_INT_ENABLE_MASK_SHIFT);
> +}
> +
> +static int max30100_read_temp(struct max30100_data *data, int *val)
> +{
> +	int ret;
> +	unsigned int reg;
> +
> +	ret = regmap_read(data->regmap, MAX30100_REG_TEMP_INTEGER, &reg);
> +	if (ret < 0)
> +		return ret;
> +	*val = reg << 4;
> +
> +	ret = regmap_read(data->regmap, MAX30100_REG_TEMP_FRACTION, &reg);
> +	if (ret < 0)
> +		return ret;
> +
> +	*val |= reg & 0xf;
> +	*val = sign_extend32(*val, 11);
> +
> +	return 0;
> +}
> +
> +static int max30100_get_temp(struct max30100_data *data, int *val)
> +{
> +	int ret;
> +
> +	/* start acquisition */
> +	ret = regmap_update_bits(data->regmap, MAX30100_REG_MODE_CONFIG,
> +				 MAX30100_REG_MODE_CONFIG_TEMP_EN,
> +				 MAX30100_REG_MODE_CONFIG_TEMP_EN);
> +	if (ret)
> +		return ret;
> +
> +	usleep_range(35000, 50000);
> +
> +	return max30100_read_temp(data, val);
> +}
> +
> +static int max30100_read_raw(struct iio_dev *indio_dev,
> +			     struct iio_chan_spec const *chan,
> +			     int *val, int *val2, long mask)
> +{
> +	struct max30100_data *data = iio_priv(indio_dev);
> +	int ret = -EINVAL;
> +
> +	mutex_lock(&indio_dev->mlock);
> +
> +	switch (mask) {
> +	case IIO_CHAN_INFO_RAW:
Move taking mlock into this case statement.

> +		/*
> +		 * Temperature reading can only be acquired while engine
> +		 * is running
> +		 */
> +		if (!iio_buffer_enabled(indio_dev))
> +			ret = -EAGAIN;
> +		else {
> +			ret = max30100_get_temp(data, val);
> +			if (!ret)
> +				ret = IIO_VAL_INT;
> +		}
> +		break;
> +	case IIO_CHAN_INFO_SCALE:
This does not need to be done under the lock so shouldn't be.
> +		*val = 1;  /* 0.0625 */
> +		*val2 = 16;
> +		ret = IIO_VAL_FRACTIONAL;
> +		break;
> +	}
> +
> +	mutex_unlock(&indio_dev->mlock);
> +
> +	return ret;
> +}
> +
> +static const struct iio_info max30100_info = {
> +	.driver_module = THIS_MODULE,
> +	.read_raw = max30100_read_raw,
> +};
> +
> +static int max30100_probe(struct i2c_client *client,
> +			  const struct i2c_device_id *id)
> +{
> +	struct max30100_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 = MAX30100_DRV_NAME;
> +	indio_dev->channels = max30100_channels;
> +	indio_dev->info = &max30100_info;
> +	indio_dev->num_channels = ARRAY_SIZE(max30100_channels);
> +	indio_dev->available_scan_masks = max30100_scan_masks;
> +	indio_dev->modes = (INDIO_BUFFER_SOFTWARE | INDIO_DIRECT_MODE);
> +	indio_dev->setup_ops = &max30100_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, &max30100_regmap_config);
> +	if (IS_ERR(data->regmap)) {
> +		dev_err(&client->dev, "regmap initialization failed.\n");
> +		return PTR_ERR(data->regmap);
> +	}
> +	max30100_set_powermode(data, false);
> +
> +	ret = max30100_chip_init(data);
> +	if (ret)
return directly.
> +		goto error_out;
> +
> +	if (client->irq <= 0) {
> +		dev_err(&client->dev, "no valid irq defined\n");
> +		ret = -EINVAL;
return directly here preferred.
> +		goto error_out;
> +	}
> +	ret = devm_request_threaded_irq(&client->dev, client->irq,
> +					NULL, max30100_interrupt_handler,
> +					IRQF_TRIGGER_FALLING | IRQF_ONESHOT,
> +					"max30100_irq", indio_dev);
> +	if (ret) {
> +		dev_err(&client->dev, "request irq (%d) failed\n", client->irq);
> +		goto error_out;
return directly here preferred.
> +	}
> +
> +	return iio_device_register(indio_dev);
> +
> +error_out:
> +	return ret;
> +}
> +
> +static int max30100_remove(struct i2c_client *client)
> +{
> +	struct iio_dev *indio_dev = i2c_get_clientdata(client);
> +	struct max30100_data *data = iio_priv(indio_dev);
> +
> +	iio_device_unregister(indio_dev);
> +	max30100_set_powermode(data, false);
> +
> +	return 0;
> +}
> +
> +static const struct i2c_device_id max30100_id[] = {
> +	{ "max30100", 0 },
> +	{}
> +};
> +MODULE_DEVICE_TABLE(i2c, max30100_id);
> +
> +static const struct of_device_id max30100_dt_ids[] = {
> +	{ .compatible = "maxim,max30100" },
> +	{ }
> +};
> +MODULE_DEVICE_TABLE(of, max30100_dt_ids);
> +
> +static struct i2c_driver max30100_driver = {
> +	.driver = {
> +		.name	= MAX30100_DRV_NAME,
> +		.of_match_table	= of_match_ptr(max30100_dt_ids),
> +	},
> +	.probe		= max30100_probe,
> +	.remove		= max30100_remove,
> +	.id_table	= max30100_id,
> +};
> +module_i2c_driver(max30100_driver);
> +
> +MODULE_AUTHOR("Matt Ranostay <mranostay@gmail.com>");
> +MODULE_DESCRIPTION("MAX30100 heart rate and pulse oximeter sensor");
> +MODULE_LICENSE("GPL");
>