Date:   Wed, 18 Dec 2019 09:52:42 +0800
From:   ruantu <mtwget@...il.com>
To:     Matt Ranostay <matt.ranostay@...sulko.com>
Cc:     Jonathan Cameron <jic23@...nel.org>,
        Hartmut Knaack <knaack.h@....de>,
        Lars-Peter Clausen <lars@...afoo.de>,
        Peter Meerwald-Stadler <pmeerw@...erw.net>,
        Tomasz Duszynski <tduszyns@...il.com>, mike.looijmans@...ic.nl,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        Arnd Bergmann <arnd@...db.de>,
        "open list:IIO SUBSYSTEM AND DRIVERS" <linux-iio@...r.kernel.org>,
        open list <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v2 1/2] iio: chemical: add support for Dynament Premier
 series single gas sensor

On Tue, Dec 17, 2019 at 2:24 AM YuDong Zhang <mtwget@...il.com> wrote:
>> Add support for Dynament Premier series single gas sensor.
>>
> Just looking the Dynament site and I assume this is for the OEM-1
> Development kit? If so you probably should
> note that in the documentation because the sensors themselves are
> likely to be used in other end products (and not
> always the dev kit)
>
> Also bit of silly question this is an UART device so why not do
> processing in userspace? :)
>
> - Matt
This is a driver implemented according to the <Dynamization Sensor 
Communications protocol>. I think the protocol is standard. This is the 
idea that emerged after the iio subsystem used serial_bus.
>> Signed-off-by: YuDong Zhang <mtwget@...il.com>
>> ---
>>   MAINTAINERS                    |   5 +
>>   drivers/iio/chemical/Kconfig   |  10 +
>>   drivers/iio/chemical/Makefile  |   1 +
>>   drivers/iio/chemical/premier.c | 366 +++++++++++++++++++++++++++++++++
>>   4 files changed, 382 insertions(+)
>>   create mode 100644 drivers/iio/chemical/premier.c
>>
>> diff --git a/MAINTAINERS b/MAINTAINERS
>> index a049abccaa26..ae228ac7adc9 100644
>> --- a/MAINTAINERS
>> +++ b/MAINTAINERS
>> @@ -5792,6 +5792,11 @@ S:       Maintained
>>   F:     drivers/media/usb/dvb-usb-v2/dvb_usb*
>>   F:     drivers/media/usb/dvb-usb-v2/usb_urb.c
>>
>> +DYNAMENT PREMIER SERIES SINGLE GAS SENSOR DRIVER
>> +M:     YuDong Zhang <mtwget@...il.com>
>> +S:     Maintained
>> +F:     drivers/iio/chemical/premier.c
>> +
>>   DYNAMIC DEBUG
>>   M:     Jason Baron <jbaron@...mai.com>
>>   S:     Maintained
>> diff --git a/drivers/iio/chemical/Kconfig b/drivers/iio/chemical/Kconfig
>> index fa4586037bb8..93c0c108245b 100644
>> --- a/drivers/iio/chemical/Kconfig
>> +++ b/drivers/iio/chemical/Kconfig
>> @@ -62,6 +62,16 @@ config IAQCORE
>>            iAQ-Core Continuous/Pulsed VOC (Volatile Organic Compounds)
>>            sensors
>>
>> +config PREMIER
>> +       tristate "Dynament Premier series sensor"
>> +       depends on SERIAL_DEV_BUS
>> +       help
>> +         Say Y here to build support for the Dynament Premier
>> +         series sensor.
>> +
>> +         To compile this driver as a module, choose M here: the module will
>> +         be called premier.
>> +
>>   config PMS7003
>>          tristate "Plantower PMS7003 particulate matter sensor"
>>          depends on SERIAL_DEV_BUS
>> diff --git a/drivers/iio/chemical/Makefile b/drivers/iio/chemical/Makefile
>> index f97270bc4034..c8e779d7cf4a 100644
>> --- a/drivers/iio/chemical/Makefile
>> +++ b/drivers/iio/chemical/Makefile
>> @@ -10,6 +10,7 @@ obj-$(CONFIG_BME680_I2C) += bme680_i2c.o
>>   obj-$(CONFIG_BME680_SPI) += bme680_spi.o
>>   obj-$(CONFIG_CCS811)           += ccs811.o
>>   obj-$(CONFIG_IAQCORE)          += ams-iaq-core.o
>> +obj-$(CONFIG_PREMIER)          += premier.o
>>   obj-$(CONFIG_PMS7003) += pms7003.o
>>   obj-$(CONFIG_SENSIRION_SGP30)  += sgp30.o
>>   obj-$(CONFIG_SPS30) += sps30.o
>> diff --git a/drivers/iio/chemical/premier.c b/drivers/iio/chemical/premier.c
>> new file mode 100644
>> index 000000000000..a226dd9d78cb
>> --- /dev/null
>> +++ b/drivers/iio/chemical/premier.c
>> @@ -0,0 +1,366 @@
>> +// SPDX-License-Identifier: GPL-2.0
>> +/*
>> + * Dynament Premier series single gas sensor driver
>> + *
>> + * Copyright (c) YuDong Zhang <mtwget@...il.com>
>> + */
>> +
>> +#include <asm/unaligned.h>
>> +#include <linux/completion.h>
>> +#include <linux/device.h>
>> +#include <linux/errno.h>
>> +#include <linux/iio/iio.h>
>> +#include <linux/jiffies.h>
>> +#include <linux/kernel.h>
>> +#include <linux/mod_devicetable.h>
>> +#include <linux/module.h>
>> +#include <linux/mutex.h>
>> +#include <linux/of.h>
>> +#include <linux/regulator/consumer.h>
>> +#include <linux/serdev.h>
>> +
>> +#define PREMIER_DRIVER_NAME "dynament-premier"
>> +
>> +#define PREMIER_DLE (0x10)
>> +#define PREMIER_CMD_RD (0x13)
>> +#define PREMIER_CMD_NAK (0x19)
>> +#define PREMIER_CMD_DAT (0x1a)
>> +#define PREMIER_EOF (0x1f)
>> +
>> +#define PREMIER_TIMEOUT msecs_to_jiffies(6000)
>> +
>> +/*
>> + * commands have following format:
>> + *
>> + * +-----+-----+---------+-----+-----+-----------+-----------+
>> + * | DLE | CMD | PAYLOAD | DLE | EOF | CKSUM MSB | CKSUM LSB |
>> + * +-----+-----+---------+-----+-----+-----------+-----------+
>> + */
>> +static const u8 premier_cmd_read_live_data_simple[] = { 0x10, 0x13, 0x06, 0x10,
>> +                                                       0x1F, 0x00, 0x58 };
>> +
>> +struct premier_frame {
>> +       u8 state;
>> +       u8 is_dat;
>> +       u8 is_nak;
>> +       u8 data_len;
>> +       u8 vi, si, gi, gj;
>> +       u8 gas[4];
>> +       u8 byte_stuffing;
>> +       u8 checksum_received[2];
>> +       u16 checksum_calculated;
>> +};
>> +
>> +struct premier_data {
>> +       struct serdev_device *serdev;
>> +       struct premier_frame frame;
>> +       struct completion frame_ready;
>> +       struct mutex lock; /* must be held whenever state gets touched */
>> +       struct regulator *vcc;
>> +};
>> +
>> +static int premier_do_cmd_read_live_data(struct premier_data *state)
>> +{
>> +       int ret;
>> +
>> +       ret = serdev_device_write(state->serdev,
>> +                                 premier_cmd_read_live_data_simple,
>> +                                 sizeof(premier_cmd_read_live_data_simple),
>> +                                 PREMIER_TIMEOUT);
>> +       if (ret < sizeof(premier_cmd_read_live_data_simple))
>> +               return ret < 0 ? ret : -EIO;
>> +
>> +       ret = wait_for_completion_interruptible_timeout(&state->frame_ready,
>> +                                                       PREMIER_TIMEOUT);
>> +
>> +       if (!ret)
>> +               ret = -ETIMEDOUT;
>> +
>> +       return ret < 0 ? ret : 0;
>> +}
>> +
>> +static s32 premier_float_to_int_clamped(const u8 *fp)
>> +{
>> +       int val = get_unaligned_le32(fp);
>> +       int mantissa = val & GENMASK(22, 0);
>> +       /* this is fine since passed float is always non-negative */
>> +       int exp = val >> 23;
>> +       int fraction, shift;
>> +
>> +       /* special case 0 */
>> +       if (!exp && !mantissa)
>> +               return 0;
>> +
>> +       exp -= 127;
>> +       if (exp < 0) {
>> +               /* return values ranging from 1 to 99 */
>> +               return ((((1 << 23) + mantissa) * 100) >> 23) >> (-exp);
>> +       }
>> +
>> +       /* return values ranging from 100 to int_max */
>> +       shift = 23 - exp;
>> +       val = (1 << exp) + (mantissa >> shift);
>> +
>> +       fraction = mantissa & GENMASK(shift - 1, 0);
>> +
>> +       return val * 100 + ((fraction * 100) >> shift);
>> +}
>> +
>> +static int premier_read_raw(struct iio_dev *indio_dev,
>> +                           struct iio_chan_spec const *chan, int *val,
>> +                           int *val2, long mask)
>> +{
>> +       struct premier_data *state = iio_priv(indio_dev);
>> +       struct premier_frame *frame = &state->frame;
>> +       int ret;
>> +       s32 val_tmp;
>> +
>> +       switch (mask) {
>> +       case IIO_CHAN_INFO_PROCESSED:
>> +
>> +               mutex_lock(&state->lock);
>> +               ret = premier_do_cmd_read_live_data(state);
>> +               if (ret) {
>> +                       mutex_unlock(&state->lock);
>> +                       return ret;
>> +               }
>> +               val_tmp = premier_float_to_int_clamped(frame->gas);
>> +               mutex_unlock(&state->lock);
>> +
>> +               *val = val_tmp / 100;
>> +               *val2 = (val_tmp % 100) * 10000;
>> +               return IIO_VAL_INT_PLUS_MICRO;
>> +       default:
>> +               return -EINVAL;
>> +       }
>> +
>> +       return -EINVAL;
>> +}
>> +
>> +static const struct iio_info premier_info = {
>> +       .read_raw = premier_read_raw,
>> +};
>> +
>> +static const struct iio_chan_spec premier_channels[] = {
>> +       {
>> +               .type = IIO_MASSCONCENTRATION,
>> +               .channel = 1,
>> +               .channel2 = IIO_MOD_CO2,
>> +               .scan_index = -1,
>> +               .info_mask_separate = BIT(IIO_CHAN_INFO_PROCESSED),
>> +               .modified = 1,
>> +       },
>> +       IIO_CHAN_SOFT_TIMESTAMP(0),
>> +};
>> +
>> +static int premier_receive_buf(struct serdev_device *serdev,
>> +                              const unsigned char *buf, size_t size)
>> +{
>> +       struct iio_dev *indio_dev = serdev_device_get_drvdata(serdev);
>> +       struct premier_data *state = iio_priv(indio_dev);
>> +       struct premier_frame *frame = &state->frame;
>> +       int i;
>> +
>> +       for (i = 0; i < size; i++) {
>> +               if (frame->state > 0 && frame->state <= 7)
>> +                       frame->checksum_calculated += buf[i];
>> +
>> +               switch (frame->state) {
>> +               case 0:
>> +                       if (buf[i] == PREMIER_DLE) {
>> +                               frame->is_dat = 0;
>> +                               frame->is_nak = 0;
>> +                               frame->checksum_calculated = buf[i];
>> +                               /* We don't initialize checksum_calculated in
>> +                                * the last state in case we didn't go
>> +                                * there because of noise
>> +                                */
>> +                               frame->state++;
>> +                       }
>> +                       break;
>> +               case 1:
>> +                       /*
>> +                        * If noise corrupts a byte in the FSM sequence,
>> +                        * we loop between state 0 and 1,
>> +                        * until we have a valid sequence of DLE&DAT or DLE&NAK
>> +                        */
>> +                       if (buf[i] == PREMIER_CMD_DAT) {
>> +                               frame->is_dat = 1;
>> +                               frame->state++;
>> +                       } else if (buf[i] == PREMIER_CMD_NAK) {
>> +                               frame->is_nak = 1;
>> +                               frame->state++;
>> +                       } else
>> +                               frame->state = 0;
>> +                       break;
>> +               case 2:
>> +                       if (frame->is_nak)
>> +                               frame->state = 0;
>> +                       else if (frame->is_dat) {
>> +                               frame->data_len = buf[i] - 4;
>> +                               /* remove version and status bytes from count */
>> +                               if (frame->data_len < 4)
>> +                                       frame->state = 0;
>> +                               /* we check for the upper limit in state 5 */
>> +                               else
>> +                                       frame->state++;
>> +                       } else
>> +                               frame->state = 0;
>> +                       break;
>> +               case 3:
>> +                       /* Just do nothing for 2 rounds to bypass
>> +                        * the 2 version bytes
>> +                        */
>> +                       if (frame->vi < 2 - 1)
>> +                               frame->vi++;
>> +                       else {
>> +                               frame->vi = 0;
>> +                               frame->state++;
>> +                       }
>> +                       break;
>> +               case 4:
>> +                       if (frame->si < 2 - 1)
>> +                               frame->si++;
>> +                       else {
>> +                               frame->si = 0;
>> +                               frame->state++;
>> +                       }
>> +                       break;
>> +               case 5:
>> +                       if (frame->gi < frame->data_len - 1) {
>> +                               if (buf[i] != PREMIER_DLE ||
>> +                                   frame->byte_stuffing) {
>> +                                       frame->gas[frame->gj] = buf[i];
>> +                                       frame->byte_stuffing = 0;
>> +                                       frame->gj++;
>> +                                       if (frame->gj >= 4)
>> +                                               frame->state = 0;
>> +                                       /* Don't violate array limits
>> +                                        * if data_len corrupt
>> +                                        */
>> +                               } else
>> +                                       frame->byte_stuffing = 1;
>> +                               frame->gi++;
>> +                       } else {
>> +                               frame->gas[frame->gj] = buf[i];
>> +                               frame->byte_stuffing = 0;
>> +                               frame->gi = 0;
>> +                               frame->gj = 0;
>> +                               frame->state++;
>> +                       }
>> +                       break;
>> +               case 6:
>> +                       if (buf[i] == PREMIER_DLE)
>> +                               frame->state++;
>> +                       else
>> +                               frame->state = 0;
>> +                       break;
>> +               case 7:
>> +                       if (buf[i] == PREMIER_EOF)
>> +                               frame->state++;
>> +                       else
>> +                               frame->state = 0;
>> +                       break;
>> +               case 8:
>> +                       frame->checksum_received[1] = buf[i];
>> +
>> +                       frame->state++;
>> +                       break;
>> +               case 9:
>> +                       frame->checksum_received[0] = buf[i];
>> +
>> +                       if (frame->checksum_calculated ==
>> +                           get_unaligned_le16(frame->checksum_received))
>> +                               complete(&state->frame_ready);
>> +
>> +                       frame->state = 0;
>> +                       break;
>> +               }
>> +       }
>> +
>> +       return size;
>> +}
>> +
>> +static const struct serdev_device_ops premier_serdev_ops = {
>> +       .receive_buf = premier_receive_buf,
>> +       .write_wakeup = serdev_device_write_wakeup,
>> +};
>> +
>> +static int premier_probe(struct serdev_device *serdev)
>> +{
>> +       struct premier_data *state;
>> +       struct iio_dev *indio_dev;
>> +       int ret;
>> +
>> +       indio_dev = devm_iio_device_alloc(&serdev->dev, sizeof(*state));
>> +       if (!indio_dev)
>> +               return -ENOMEM;
>> +
>> +       state = iio_priv(indio_dev);
>> +       serdev_device_set_drvdata(serdev, indio_dev);
>> +       state->serdev = serdev;
>> +       indio_dev->dev.parent = &serdev->dev;
>> +       indio_dev->info = &premier_info;
>> +       indio_dev->name = PREMIER_DRIVER_NAME;
>> +       indio_dev->channels = premier_channels;
>> +       indio_dev->num_channels = ARRAY_SIZE(premier_channels);
>> +       indio_dev->modes = INDIO_DIRECT_MODE;
>> +
>> +       mutex_init(&state->lock);
>> +       init_completion(&state->frame_ready);
>> +
>> +       state->vcc = devm_regulator_get(&serdev->dev, "vcc");
>> +       if (IS_ERR(state->vcc)) {
>> +               ret = PTR_ERR(state->vcc);
>> +               return ret;
>> +       }
>> +
>> +       serdev_device_set_client_ops(serdev, &premier_serdev_ops);
>> +       ret = devm_serdev_device_open(&serdev->dev, serdev);
>> +       if (ret)
>> +               return ret;
>> +
>> +       serdev_device_set_baudrate(serdev, 9600);
>> +       serdev_device_set_flow_control(serdev, false);
>> +
>> +       ret = serdev_device_set_parity(serdev, SERDEV_PARITY_NONE);
>> +       if (ret)
>> +               return ret;
>> +
>> +       if (state->vcc) {
>> +               ret = regulator_enable(state->vcc);
>> +               if (ret)
>> +                       return ret;
>> +       }
>> +
>> +       return devm_iio_device_register(&serdev->dev, indio_dev);
>> +}
>> +
>> +static void premier_remove(struct serdev_device *serdev)
>> +{
>> +       struct iio_dev *indio_dev = serdev_device_get_drvdata(serdev);
>> +       struct premier_data *state = iio_priv(indio_dev);
>> +
>> +       if (state->vcc)
>> +               regulator_disable(state->vcc);
>> +}
>> +
>> +static const struct of_device_id premier_of_match[] = {
>> +       { .compatible = "dynament,premier" },
>> +       {}
>> +};
>> +MODULE_DEVICE_TABLE(of, premier_of_match);
>> +
>> +static struct serdev_device_driver premier_driver = {
>> +       .driver = {
>> +               .name = PREMIER_DRIVER_NAME,
>> +               .of_match_table = premier_of_match,
>> +       },
>> +       .probe = premier_probe,
>> +       .remove = premier_remove,
>> +};
>> +module_serdev_device_driver(premier_driver);
>> +
>> +MODULE_AUTHOR("YuDong Zhang <mtwget@...il.com>");
>> +MODULE_DESCRIPTION("Dynament Premier series single gas sensor driver");
>> +MODULE_LICENSE("GPL v2");
>> --
>> 2.24.1
>>

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