Re: [RFC v2 1/1] iio: light: add MAX30100 oximeter driver support

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On Fri, Nov 20, 2015 at 8:40 AM, Peter Meerwald-Stadler
<pmeerw@xxxxxxxxxx> wrote:
> On Wed, 18 Nov 2015, 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
>
> red? this refers to a LED with visible red color?
> more nitpicking below
>
>> be processed in userspace to determine heart rate and blood oxygen
>> levels.
>>
>> Signed-off-by: Matt Ranostay <mranostay@xxxxxxxxx>
>> ---
>>  .../devicetree/bindings/iio/light/max30100.txt     |  22 ++
>>  drivers/iio/Kconfig                                |   1 +
>>  drivers/iio/Makefile                               |   1 +
>>  drivers/iio/health/Kconfig                         |  21 +
>>  drivers/iio/health/Makefile                        |   7 +
>>  drivers/iio/health/max30100.c                      | 423 +++++++++++++++++++++
>>  6 files changed, 475 insertions(+)
>>  create mode 100644 Documentation/devicetree/bindings/iio/light/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/light/max30100.txt b/Documentation/devicetree/bindings/iio/light/max30100.txt
>> new file mode 100644
>> index 0000000..435d6fc
>> --- /dev/null
>> +++ b/Documentation/devicetree/bindings/iio/light/max30100.txt
>> @@ -0,0 +1,22 @@
>> +* 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
>
> I2C
>
>> +  - interrupt-parent: should be the phandle for the interrupt controller
>> +  - interrupts : the sole interrupt generated by the device
>
> no space before : for consistency
>
>> +
>> +  Refer to interrupt-controller/interrupts.txt for generic interrupt client
>> +  node bindings.
>> +
>> +Example:
>> +
>> +max30100@57 {
>> +     compatible = "maxim,max30100";
>> +     reg = <0x57>;
>> +     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..30d4ca0
>> --- /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
>
> put a full stop (.) at the end of the sentence maybe :)
>
>> +
>> +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..3ad6b31
>> --- /dev/null
>> +++ b/drivers/iio/health/max30100.c
>> @@ -0,0 +1,423 @@
>> +/*
>> + * max30100.c - Support for MAX30100 heart rate and pulse oximeter sensor
>> + *
>> + * Copyright (C) 2015 Matt Ranostay <mranostay@xxxxxxxxx>
>> + *
>> + * 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.
>> + *
>> + */
>> +
>> +#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_ENABLE                      0x01
>> +#define MAX30100_REG_INT_ENABLE_HR_EN                BIT(0)
>> +#define MAX30100_REG_INT_ENABLE_SPO2_EN              BIT(1)
>> +#define MAX30100_REG_INT_ENABLE_MASK         0xf0
>> +#define MAX30100_REG_INT_ENABLE_MASK_SHIFT   4
>> +
>> +#define MAX30100_REG_FIFO_DATA                       0x05
>> +
>> +#define MAX30100_REG_MODE_CONFIG             0x06
>> +#define MAX30100_REG_MODE_CONFIG_MODE_HR_EN  BIT(0)
>> +#define MAX30100_REG_MODE_CONFIG_MODE_SPO2_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 iio_dev *indio_dev;
>> +     struct mutex lock;
>> +     struct regmap *regmap;
>> +
>> +     u8 buffer[4]; /* 4 8-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_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_LED_CONFIG,
>> +     .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,
>> +
>> +             .scan_index = 0,
>> +             .scan_type = {
>> +                     .sign = 'u',
>> +                     .realbits = 16,
>> +                     .storagebits = 16,
>> +                     .endianness = IIO_BE,
>> +             },
>> +     },
>> +     {
>> +             .type = IIO_INTENSITY,
>> +             .channel2 = IIO_MOD_LIGHT_RED,
>> +
>> +             .scan_index = 1,
>> +             .scan_type = {
>> +                     .sign = 'u',
>> +                     .realbits = 16,
>
> max30100_interrupt_handler() reads 4 bytes?!
>
> description of buffer in max30100_data:
> u8 buffer[4]; /* 4 8-bit channels */
> this is confusing; maybe __be16 buffer[2]?
>
>> +                     .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_buffer_postenable(struct iio_dev *indio_dev)
>> +{
>> +     struct max30100_data *data = iio_priv(indio_dev);
>> +
>> +     return max30100_set_powermode(data, true);
>> +}
>> +
>> +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)
>> +{
>> +     int ret, val;
>> +
>> +     ret = regmap_read(data->regmap, MAX30100_REG_INT_STATUS, &val);
>> +     if (ret)
>> +             return ret;
>> +
>> +     return !!(val >> 4);
>> +}
>> +
>> +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;
>> +
>> +     mutex_lock(&data->lock);
>> +
>> +     while (max30100_fifo_is_empty(data) != 0) {
>> +             ret = regmap_bulk_read(data->regmap, MAX30100_REG_FIFO_DATA,
>> +                                   &data->buffer, 4);
>> +
>> +             if (ret)
>> +                     goto err_read;
>> +
>> +             iio_push_to_buffers(data->indio_dev, data->buffer);
>> +     }
>> +
>> +err_read:
>> +     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 + HR 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 + HR interrupts */
>> +     return regmap_update_bits(data->regmap, MAX30100_REG_INT_ENABLE,
>> +                             MAX30100_REG_INT_ENABLE_MASK,
>> +                             (MAX30100_REG_INT_ENABLE_HR_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;
>> +     int reg;
>> +
>> +     ret = regmap_read(data->regmap, MAX30100_REG_TEMP_INTEGER, &reg);
>> +     if (ret < 0)
>> +             return ret;
>> +     *val = reg << 4;
>
> note that this is a signed value; I think negative temperatures are not
> processed correctly
>
>> +
>> +     ret = regmap_read(data->regmap, MAX30100_REG_TEMP_FRACTION, &reg);
>> +     if (ret < 0)
>> +             return ret;
>> +     *val |= reg & 0xf;
>> +
>> +     return 0;
>> +}
>> +
>> +static int max30100_get_temp(struct max30100_data *data, int *val)
>> +{
>> +     int ret;
>> +     int tries = 3;
>> +
>> +     /* 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;
>> +
>> +     while (tries--) {
>> +             int reg;
>> +
>> +             usleep_range(29000, 40000);
>> +
>> +             ret = regmap_read(data->regmap, MAX30100_REG_MODE_CONFIG, &reg);
>> +             if (ret < 0)
>> +                     break;
>> +
>> +             /* bit reset to zero when reading is ready */
>> +             if (!(reg & MAX30100_REG_MODE_CONFIG_TEMP_EN)) {
>> +                     ret = max30100_read_temp(data, val);
>> +                     break;
>> +             }
>> +             ret = -EIO;
>> +     }
>> +
>> +     return ret;
>> +}
>> +
>> +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);
>> +
>> +     /* temperature reading can only be acquired while engine is running */
>> +     if (!iio_buffer_enabled(indio_dev) && mask == IIO_CHAN_INFO_RAW) {
>> +             ret = -EAGAIN;
>> +             goto error_again;
>> +     }
>> +
>> +     switch (mask) {
>> +     case IIO_CHAN_INFO_RAW:
>> +             ret = max30100_get_temp(data, val);
>> +             if (!ret)
>
> what if ret < 0?
> _get_temp() checks for ret < 0

If ret is other than 0 (greater or lless) it will return the error
code from *get_temp. Wouldn't this be the expected way to do this?

>
> INTENSITY channels cannot be raw_read?
>
>> +                     ret = IIO_VAL_INT;
>> +             break;
>> +     case IIO_CHAN_INFO_SCALE:
>> +             *val = 1;  /* 0.0625 */
>> +             *val2 = 16;
>> +             ret = IIO_VAL_FRACTIONAL;
>> +             break;
>> +     }
>> +
>> +error_again:
>> +     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;
>> +
>> +     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)
>> +             goto error_out;
>> +
>> +     if (client->irq <= 0) {
>> +             dev_err(&client->dev, "no valid irq defined\n");
>> +             ret = -EINVAL;
>> +             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 iio_device_register(indio_dev);
>
> newline here
>
>> +error_out:
>
> drop newline
>
>> +
>> +     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@xxxxxxxxx>");
>> +MODULE_DESCRIPTION("MAX30100 heart rate and pulse oximeter sensor");
>> +MODULE_LICENSE("GPL");
>>
>
> --
>
> Peter Meerwald-Stadler
> +43-664-2444418 (mobile)
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