// SPDX-License-Identifier: GPL-2.0
/*
 * Plantower PMS7003 particulate matter sensor driver
 *
 * Copyright (c) Tomasz Duszynski <tduszyns@gmail.com>
 */

#include <linux/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 PMS7003_DRIVER_NAME "pms7003"

#define PMS7003_MAGIC 0x424d
/* last 2 data bytes hold frame checksum */
#define PMS7003_MAX_DATA_LENGTH 28
#define PMS7003_CHECKSUM_LENGTH 2
#define PMS7003_PM10_OFFSET 10
#define PMS7003_PM2P5_OFFSET 8
#define PMS7003_PM1_OFFSET 6

#define PMS7003_TIMEOUT msecs_to_jiffies(6000)
#define PMS7003_CMD_LENGTH 7
#define PMS7003_PM_MAX 1000
#define PMS7003_PM_MIN 0

enum {
	PM1,
	PM2P5,
	PM10,
};

enum pms7003_cmd {
	CMD_WAKEUP,
	CMD_ENTER_PASSIVE_MODE,
	CMD_READ_PASSIVE,
	CMD_SLEEP,
};

/*
 * commands have following format:
 *
 * +------+------+-----+------+-----+-----------+-----------+
 * | 0x42 | 0x4d | cmd | 0x00 | arg | cksum msb | cksum lsb |
 * +------+------+-----+------+-----+-----------+-----------+
 */
static const u8 pms7003_cmd_tbl[][PMS7003_CMD_LENGTH] = {
	[CMD_WAKEUP] = { 0x42, 0x4d, 0xe4, 0x00, 0x01, 0x01, 0x74 },
	[CMD_ENTER_PASSIVE_MODE] = { 0x42, 0x4d, 0xe1, 0x00, 0x00, 0x01, 0x70 },
	[CMD_READ_PASSIVE] = { 0x42, 0x4d, 0xe2, 0x00, 0x00, 0x01, 0x71 },
	[CMD_SLEEP] = { 0x42, 0x4d, 0xe4, 0x00, 0x00, 0x01, 0x73 },
};

struct pms7003_frame {
	u8 data[PMS7003_MAX_DATA_LENGTH];
	u16 expected_length;
	u16 length;
};

struct pms7003_state {
	struct serdev_device *serdev;
	struct pms7003_frame frame;
	struct completion frame_ready;
	struct mutex lock; /* must be held whenever state gets touched */
	/* Used to construct scan to push to the IIO buffer */
	struct {
		u16 data[3]; /* PM1, PM2P5, PM10 */
		s64 ts;
	} scan;
};

static int pms7003_do_cmd(struct pms7003_state *state, enum pms7003_cmd cmd)
{
	int ret;

	ret = serdev_device_write(state->serdev, pms7003_cmd_tbl[cmd],
				  PMS7003_CMD_LENGTH, PMS7003_TIMEOUT);
	if (ret < PMS7003_CMD_LENGTH)
		return ret < 0 ? ret : -EIO;

	ret = wait_for_completion_interruptible_timeout(&state->frame_ready,
							PMS7003_TIMEOUT);
	if (!ret)
		ret = -ETIMEDOUT;

	return ret < 0 ? ret : 0;
}

static u16 pms7003_get_pm(const u8 *data)
{
	return clamp_val(get_unaligned_be16(data),
			 PMS7003_PM_MIN, PMS7003_PM_MAX);
}

static irqreturn_t pms7003_trigger_handler(int irq, void *p)
{
	struct iio_poll_func *pf = p;
	struct iio_dev *indio_dev = pf->indio_dev;
	struct pms7003_state *state = iio_priv(indio_dev);
	struct pms7003_frame *frame = &state->frame;
	int ret;

	mutex_lock(&state->lock);
	ret = pms7003_do_cmd(state, CMD_READ_PASSIVE);
	if (ret) {
		mutex_unlock(&state->lock);
		goto err;
	}

	state->scan.data[PM1] =
		pms7003_get_pm(frame->data + PMS7003_PM1_OFFSET);
	state->scan.data[PM2P5] =
		pms7003_get_pm(frame->data + PMS7003_PM2P5_OFFSET);
	state->scan.data[PM10] =
		pms7003_get_pm(frame->data + PMS7003_PM10_OFFSET);
	mutex_unlock(&state->lock);

	iio_push_to_buffers_with_timestamp(indio_dev, &state->scan,
					   iio_get_time_ns(indio_dev));
err:
	iio_trigger_notify_done(indio_dev->trig);

	return IRQ_HANDLED;
}

static int pms7003_read_raw(struct iio_dev *indio_dev,
			    struct iio_chan_spec const *chan,
			    int *val, int *val2, long mask)
{
	struct pms7003_state *state = iio_priv(indio_dev);
	struct pms7003_frame *frame = &state->frame;
	int ret;

	switch (mask) {
	case IIO_CHAN_INFO_PROCESSED:
		switch (chan->type) {
		case IIO_MASSCONCENTRATION:
			mutex_lock(&state->lock);
			ret = pms7003_do_cmd(state, CMD_READ_PASSIVE);
			if (ret) {
				mutex_unlock(&state->lock);
				return ret;
			}

			*val = pms7003_get_pm(frame->data + chan->address);
			mutex_unlock(&state->lock);

			return IIO_VAL_INT;
		default:
			return -EINVAL;
		}
	}

	return -EINVAL;
}

static const struct iio_info pms7003_info = {
	.read_raw = pms7003_read_raw,
};

#define PMS7003_CHAN(_index, _mod, _addr) { \
	.type = IIO_MASSCONCENTRATION, \
	.modified = 1, \
	.channel2 = IIO_MOD_ ## _mod, \
	.address = _addr, \
	.info_mask_separate = BIT(IIO_CHAN_INFO_PROCESSED), \
	.scan_index = _index, \
	.scan_type = { \
		.sign = 'u', \
		.realbits = 10, \
		.storagebits = 16, \
		.endianness = IIO_CPU, \
	}, \
}

static const struct iio_chan_spec pms7003_channels[] = {
	PMS7003_CHAN(0, PM1, PMS7003_PM1_OFFSET),
	PMS7003_CHAN(1, PM2P5, PMS7003_PM2P5_OFFSET),
	PMS7003_CHAN(2, PM10, PMS7003_PM10_OFFSET),
	IIO_CHAN_SOFT_TIMESTAMP(3),
};

static u16 pms7003_calc_checksum(struct pms7003_frame *frame)
{
	u16 checksum = (PMS7003_MAGIC >> 8) + (u8)(PMS7003_MAGIC & 0xff) +
		       (frame->length >> 8) + (u8)frame->length;
	int i;

	for (i = 0; i < frame->length - PMS7003_CHECKSUM_LENGTH; i++)
		checksum += frame->data[i];

	return checksum;
}

static bool pms7003_frame_is_okay(struct pms7003_frame *frame)
{
	int offset = frame->length - PMS7003_CHECKSUM_LENGTH;
	u16 checksum = get_unaligned_be16(frame->data + offset);

	return checksum == pms7003_calc_checksum(frame);
}

static size_t pms7003_receive_buf(struct serdev_device *serdev, const u8 *buf,
				  size_t size)
{
	struct iio_dev *indio_dev = serdev_device_get_drvdata(serdev);
	struct pms7003_state *state = iio_priv(indio_dev);
	struct pms7003_frame *frame = &state->frame;
	size_t num;

	if (!frame->expected_length) {
		u16 magic;

		/* wait for SOF and data length */
		if (size < 4)
			return 0;

		magic = get_unaligned_be16(buf);
		if (magic != PMS7003_MAGIC)
			return 2;

		num = get_unaligned_be16(buf + 2);
		if (num <= PMS7003_MAX_DATA_LENGTH) {
			frame->expected_length = num;
			frame->length = 0;
		}

		return 4;
	}

	num = min(size, (size_t)(frame->expected_length - frame->length));
	memcpy(frame->data + frame->length, buf, num);
	frame->length += num;

	if (frame->length == frame->expected_length) {
		if (pms7003_frame_is_okay(frame))
			complete(&state->frame_ready);

		frame->expected_length = 0;
	}

	return num;
}

static const struct serdev_device_ops pms7003_serdev_ops = {
	.receive_buf = pms7003_receive_buf,
	.write_wakeup = serdev_device_write_wakeup,
};

static void pms7003_stop(void *data)
{
	struct pms7003_state *state = data;

	pms7003_do_cmd(state, CMD_SLEEP);
}

static const unsigned long pms7003_scan_masks[] = { 0x07, 0x00 };

static int pms7003_probe(struct serdev_device *serdev)
{
	struct pms7003_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->info = &pms7003_info;
	indio_dev->name = PMS7003_DRIVER_NAME;
	indio_dev->channels = pms7003_channels;
	indio_dev->num_channels = ARRAY_SIZE(pms7003_channels);
	indio_dev->modes = INDIO_DIRECT_MODE;
	indio_dev->available_scan_masks = pms7003_scan_masks;

	mutex_init(&state->lock);
	init_completion(&state->frame_ready);

	serdev_device_set_client_ops(serdev, &pms7003_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;

	ret = pms7003_do_cmd(state, CMD_WAKEUP);
	if (ret) {
		dev_err(&serdev->dev, "failed to wakeup sensor\n");
		return ret;
	}

	ret = pms7003_do_cmd(state, CMD_ENTER_PASSIVE_MODE);
	if (ret) {
		dev_err(&serdev->dev, "failed to enter passive mode\n");
		return ret;
	}

	ret = devm_add_action_or_reset(&serdev->dev, pms7003_stop, state);
	if (ret)
		return ret;

	ret = devm_iio_triggered_buffer_setup(&serdev->dev, indio_dev, NULL,
					      pms7003_trigger_handler, NULL);
	if (ret)
		return ret;

	return devm_iio_device_register(&serdev->dev, indio_dev);
}

static const struct of_device_id pms7003_of_match[] = {
	{ .compatible = "plantower,pms1003" },
	{ .compatible = "plantower,pms3003" },
	{ .compatible = "plantower,pms5003" },
	{ .compatible = "plantower,pms6003" },
	{ .compatible = "plantower,pms7003" },
	{ .compatible = "plantower,pmsa003" },
	{ }
};
MODULE_DEVICE_TABLE(of, pms7003_of_match);

static struct serdev_device_driver pms7003_driver = {
	.driver = {
		.name = PMS7003_DRIVER_NAME,
		.of_match_table = pms7003_of_match,
	},
	.probe = pms7003_probe,
};
module_serdev_device_driver(pms7003_driver);

MODULE_AUTHOR("Tomasz Duszynski <tduszyns@gmail.com>");
MODULE_DESCRIPTION("Plantower PMS7003 particulate matter sensor driver");
MODULE_LICENSE("GPL v2");