Date:   Tue, 10 Dec 2019 13:37:21 +0800
From:   ruantu <mtwget@...il.com>
To:     jic23@...nel.org
Cc:     mtwget@...il.com, knaack.h@....de, lars@...afoo.de,
        pmeerw@...erw.net, linux-iio@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: [PATCH 1/2] iio: chemical: add support for Dynament Premier series single gas sensor

Add support for Dynament Premier series single gas sensor.

Signed-off-by: ruantu <mtwget@...il.com>
---
 MAINTAINERS                    |   5 +
 drivers/iio/chemical/Kconfig   |  11 ++
 drivers/iio/chemical/Makefile  |   1 +
 drivers/iio/chemical/premier.c | 349 +++++++++++++++++++++++++++++++++
 4 files changed, 366 insertions(+)
 create mode 100644 drivers/iio/chemical/premier.c

diff --git a/MAINTAINERS b/MAINTAINERS
index 02d5278a4c9a..18c26558ddfe 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -13133,6 +13133,11 @@ F:	drivers/i2c/busses/i2c-puv3.c
 F:	drivers/video/fbdev/fb-puv3.c
 F:	drivers/rtc/rtc-puv3.c
 
+DYNAMENT PREMIER SERIES SINGLE GAS SENSOR DRIVER
+M:	ruantu <mtwget@...il.com>
+S:	Maintained
+F:	drivers/iio/chemical/premier.c
+
 PLANTOWER PMS7003 AIR POLLUTION SENSOR DRIVER
 M:	Tomasz Duszynski <tduszyns@...il.com>
 S:	Maintained
diff --git a/drivers/iio/chemical/Kconfig b/drivers/iio/chemical/Kconfig
index fa4586037bb8..b75903a5a15c 100644
--- a/drivers/iio/chemical/Kconfig
+++ b/drivers/iio/chemical/Kconfig
@@ -62,6 +62,17 @@ config IAQCORE
 	  iAQ-Core Continuous/Pulsed VOC (Volatile Organic Compounds)
 	  sensors
 
+config PREMIER
+	tristate "Dynament Premier series sensor"
+	depends on SERIAL_DEV_BUS
+	select IIO_TRIGGERED_BUFFER
+	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..5681e2caa03b
--- /dev/null
+++ b/drivers/iio/chemical/premier.c
@@ -0,0 +1,349 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Dynament Premier series single gas sensor driver
+ *
+ * Copyright (c) ruantu <mtwget@...il.com>
+ */
+
+#include <asm/unaligned.h>
+#include <linux/completion.h>
+#include <linux/device.h>
+#include <linux/errno.h>
+#include <linux/iio/buffer.h>
+#include <linux/iio/iio.h>
+#include <linux/iio/trigger_consumer.h>
+#include <linux/iio/triggered_buffer.h>
+#include <linux/jiffies.h>
+#include <linux/kernel.h>
+#include <linux/mod_devicetable.h>
+#include <linux/module.h>
+#include <linux/mutex.h>
+#include <linux/serdev.h>
+
+#define PREMIER_DRIVER_NAME "premier"
+
+#define DLE (0x10)
+#define CMD_RD (0x13)
+#define CMD_NAK (0x19)
+#define CMD_DAT (0x1a)
+#define EOFF (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_state {
+	struct serdev_device *serdev;
+	struct premier_frame frame;
+	struct completion frame_ready;
+	struct mutex lock;	/* must be held whenever state gets touched */
+};
+
+static int premier_do_cmd_read_live_data(struct premier_state *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_state *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_CONCENTRATION,
+	 .channel = 1,
+	 .info_mask_separate = BIT(IIO_CHAN_INFO_PROCESSED),
+	 .scan_index = -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_state *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] == 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] == CMD_DAT) {
+				frame->is_dat = 1;
+				frame->state++;
+			} else if (buf[i] == 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] != 0x10 || 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] == DLE)
+				frame->state++;
+			else
+				frame->state = 0;
+			break;
+		case 7:
+			if (buf[i] == EOFF)
+				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 const unsigned long premier_scan_masks[] = { 0x07, 0x00 };
+
+static int premier_probe(struct serdev_device *serdev)
+{
+	struct premier_state *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;
+	indio_dev->available_scan_masks = premier_scan_masks;
+
+	mutex_init(&state->lock);
+	init_completion(&state->frame_ready);
+
+	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;
+
+	return devm_iio_device_register(&serdev->dev, indio_dev);
+}
+
+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,
+};
+
+module_serdev_device_driver(premier_driver);
+
+MODULE_AUTHOR("ruantu <mtwget@...il.com>");
+MODULE_DESCRIPTION("Dynament Premier series single gas sensor driver");
+MODULE_LICENSE("GPL v2");
-- 
2.24.0

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