linux/drivers/iio/adc/max1027.c

// SPDX-License-Identifier: GPL-2.0-only
 /*
  * iio/adc/max1027.c
  * Copyright (C) 2014 Philippe Reynes
  *
  * based on linux/drivers/iio/ad7923.c
  * Copyright 2011 Analog Devices Inc (from AD7923 Driver)
  * Copyright 2012 CS Systemes d'Information
  *
  * max1027.c
  *
  * Partial support for max1027 and similar chips.
  */

#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/mod_devicetable.h>
#include <linux/spi/spi.h>
#include <linux/delay.h>

#include <linux/iio/iio.h>
#include <linux/iio/buffer.h>
#include <linux/iio/trigger.h>
#include <linux/iio/trigger_consumer.h>
#include <linux/iio/triggered_buffer.h>

#define MAX1027_CONV_REG  BIT(7)
#define MAX1027_SETUP_REG BIT(6)
#define MAX1027_AVG_REG   BIT(5)
#define MAX1027_RST_REG   BIT(4)

/* conversion register */
#define MAX1027_TEMP      BIT(0)
#define MAX1027_SCAN_0_N  (0x00 << 1)
#define MAX1027_SCAN_N_M  (0x01 << 1)
#define MAX1027_SCAN_N    (0x02 << 1)
#define MAX1027_NOSCAN    (0x03 << 1)
#define MAX1027_CHAN(n)   ((n) << 3)

/* setup register */
#define MAX1027_UNIPOLAR  0x02
#define MAX1027_BIPOLAR   0x03
#define MAX1027_REF_MODE0 (0x00 << 2)
#define MAX1027_REF_MODE1 (0x01 << 2)
#define MAX1027_REF_MODE2 (0x02 << 2)
#define MAX1027_REF_MODE3 (0x03 << 2)
#define MAX1027_CKS_MODE0 (0x00 << 4)
#define MAX1027_CKS_MODE1 (0x01 << 4)
#define MAX1027_CKS_MODE2 (0x02 << 4)
#define MAX1027_CKS_MODE3 (0x03 << 4)

/* averaging register */
#define MAX1027_NSCAN_4   0x00
#define MAX1027_NSCAN_8   0x01
#define MAX1027_NSCAN_12  0x02
#define MAX1027_NSCAN_16  0x03
#define MAX1027_NAVG_4    (0x00 << 2)
#define MAX1027_NAVG_8    (0x01 << 2)
#define MAX1027_NAVG_16   (0x02 << 2)
#define MAX1027_NAVG_32   (0x03 << 2)
#define MAX1027_AVG_EN    BIT(4)

/* Device can achieve 300ksps so we assume a 3.33us conversion delay */
#define MAX1027_CONVERSION_UDELAY 4

enum max1027_id {
	max1027,
	max1029,
	max1031,
	max1227,
	max1229,
	max1231,
};

static const struct spi_device_id max1027_id[] = {
	{"max1027", max1027},
	{"max1029", max1029},
	{"max1031", max1031},
	{"max1227", max1227},
	{"max1229", max1229},
	{"max1231", max1231},
	{}
};
MODULE_DEVICE_TABLE(spi, max1027_id);

static const struct of_device_id max1027_adc_dt_ids[] = {
	{ .compatible = "maxim,max1027" },
	{ .compatible = "maxim,max1029" },
	{ .compatible = "maxim,max1031" },
	{ .compatible = "maxim,max1227" },
	{ .compatible = "maxim,max1229" },
	{ .compatible = "maxim,max1231" },
	{},
};
MODULE_DEVICE_TABLE(of, max1027_adc_dt_ids);

#define MAX1027_V_CHAN(index, depth)					\
	{								\
		.type = IIO_VOLTAGE,					\
		.indexed = 1,						\
		.channel = index,					\
		.info_mask_separate = BIT(IIO_CHAN_INFO_RAW),		\
		.info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE),	\
		.scan_index = index + 1,				\
		.scan_type = {						\
			.sign = 'u',					\
			.realbits = depth,				\
			.storagebits = 16,				\
			.shift = (depth == 10) ? 2 : 0,			\
			.endianness = IIO_BE,				\
		},							\
	}

#define MAX1027_T_CHAN							\
	{								\
		.type = IIO_TEMP,					\
		.channel = 0,						\
		.info_mask_separate = BIT(IIO_CHAN_INFO_RAW),		\
		.info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE),	\
		.scan_index = 0,					\
		.scan_type = {						\
			.sign = 'u',					\
			.realbits = 12,					\
			.storagebits = 16,				\
			.endianness = IIO_BE,				\
		},							\
	}

#define MAX1X27_CHANNELS(depth)			\
	MAX1027_T_CHAN,				\
	MAX1027_V_CHAN(0, depth),		\
	MAX1027_V_CHAN(1, depth),		\
	MAX1027_V_CHAN(2, depth),		\
	MAX1027_V_CHAN(3, depth),		\
	MAX1027_V_CHAN(4, depth),		\
	MAX1027_V_CHAN(5, depth),		\
	MAX1027_V_CHAN(6, depth),		\
	MAX1027_V_CHAN(7, depth)

#define MAX1X29_CHANNELS(depth)			\
	MAX1X27_CHANNELS(depth),		\
	MAX1027_V_CHAN(8, depth),		\
	MAX1027_V_CHAN(9, depth),		\
	MAX1027_V_CHAN(10, depth),		\
	MAX1027_V_CHAN(11, depth)

#define MAX1X31_CHANNELS(depth)			\
	MAX1X29_CHANNELS(depth),		\
	MAX1027_V_CHAN(12, depth),		\
	MAX1027_V_CHAN(13, depth),		\
	MAX1027_V_CHAN(14, depth),		\
	MAX1027_V_CHAN(15, depth)

static const struct iio_chan_spec max1027_channels[] = {
	MAX1X27_CHANNELS(10),
};

static const struct iio_chan_spec max1029_channels[] = {
	MAX1X29_CHANNELS(10),
};

static const struct iio_chan_spec max1031_channels[] = {
	MAX1X31_CHANNELS(10),
};

static const struct iio_chan_spec max1227_channels[] = {
	MAX1X27_CHANNELS(12),
};

static const struct iio_chan_spec max1229_channels[] = {
	MAX1X29_CHANNELS(12),
};

static const struct iio_chan_spec max1231_channels[] = {
	MAX1X31_CHANNELS(12),
};

/*
 * These devices are able to scan from 0 to N, N being the highest voltage
 * channel requested by the user. The temperature can be included or not,
 * but cannot be retrieved alone. Based on the below
 * ->available_scan_masks, the core will select the most appropriate
 * ->active_scan_mask and the "minimum" number of channels will be
 * scanned and pushed to the buffers.
 *
 * For example, if the user wants channels 1, 4 and 5, all channels from
 * 0 to 5 will be scanned and pushed to the IIO buffers. The core will then
 * filter out the unneeded samples based on the ->active_scan_mask that has
 * been selected and only channels 1, 4 and 5 will be available to the user
 * in the shared buffer.
 */
#define MAX1X27_SCAN_MASK_TEMP BIT(0)

#define MAX1X27_SCAN_MASKS(temp)					\
	GENMASK(1, 1 - (temp)), GENMASK(2, 1 - (temp)),			\
	GENMASK(3, 1 - (temp)), GENMASK(4, 1 - (temp)),			\
	GENMASK(5, 1 - (temp)), GENMASK(6, 1 - (temp)),			\
	GENMASK(7, 1 - (temp)), GENMASK(8, 1 - (temp))

#define MAX1X29_SCAN_MASKS(temp)					\
	MAX1X27_SCAN_MASKS(temp),					\
	GENMASK(9, 1 - (temp)), GENMASK(10, 1 - (temp)),		\
	GENMASK(11, 1 - (temp)), GENMASK(12, 1 - (temp))

#define MAX1X31_SCAN_MASKS(temp)					\
	MAX1X29_SCAN_MASKS(temp),					\
	GENMASK(13, 1 - (temp)), GENMASK(14, 1 - (temp)),		\
	GENMASK(15, 1 - (temp)), GENMASK(16, 1 - (temp))

static const unsigned long max1027_available_scan_masks[] = {
	MAX1X27_SCAN_MASKS(0),
	MAX1X27_SCAN_MASKS(1),
	0x00000000,
};

static const unsigned long max1029_available_scan_masks[] = {
	MAX1X29_SCAN_MASKS(0),
	MAX1X29_SCAN_MASKS(1),
	0x00000000,
};

static const unsigned long max1031_available_scan_masks[] = {
	MAX1X31_SCAN_MASKS(0),
	MAX1X31_SCAN_MASKS(1),
	0x00000000,
};

struct max1027_chip_info {
	const struct iio_chan_spec *channels;
	unsigned int num_channels;
	const unsigned long *available_scan_masks;
};

static const struct max1027_chip_info max1027_chip_info_tbl[] = {
	[max1027] = {
		.channels = max1027_channels,
		.num_channels = ARRAY_SIZE(max1027_channels),
		.available_scan_masks = max1027_available_scan_masks,
	},
	[max1029] = {
		.channels = max1029_channels,
		.num_channels = ARRAY_SIZE(max1029_channels),
		.available_scan_masks = max1029_available_scan_masks,
	},
	[max1031] = {
		.channels = max1031_channels,
		.num_channels = ARRAY_SIZE(max1031_channels),
		.available_scan_masks = max1031_available_scan_masks,
	},
	[max1227] = {
		.channels = max1227_channels,
		.num_channels = ARRAY_SIZE(max1227_channels),
		.available_scan_masks = max1027_available_scan_masks,
	},
	[max1229] = {
		.channels = max1229_channels,
		.num_channels = ARRAY_SIZE(max1229_channels),
		.available_scan_masks = max1029_available_scan_masks,
	},
	[max1231] = {
		.channels = max1231_channels,
		.num_channels = ARRAY_SIZE(max1231_channels),
		.available_scan_masks = max1031_available_scan_masks,
	},
};

struct max1027_state {
	const struct max1027_chip_info	*info;
	struct spi_device		*spi;
	struct iio_trigger		*trig;
	__be16				*buffer;
	struct mutex			lock;
	struct completion		complete;

	u8				reg __aligned(IIO_DMA_MINALIGN);
};

static int max1027_wait_eoc(struct iio_dev *indio_dev)
{
	struct max1027_state *st = iio_priv(indio_dev);
	unsigned int conversion_time = MAX1027_CONVERSION_UDELAY;
	int ret;

	if (st->spi->irq) {
		ret = wait_for_completion_timeout(&st->complete,
						  msecs_to_jiffies(1000));
		reinit_completion(&st->complete);
		if (!ret)
			return -ETIMEDOUT;
	} else {
		if (indio_dev->active_scan_mask)
			conversion_time *= hweight32(*indio_dev->active_scan_mask);

		usleep_range(conversion_time, conversion_time * 2);
	}

	return 0;
}

/* Scan from chan 0 to the highest requested channel. Include temperature on demand. */
static int max1027_configure_chans_and_start(struct iio_dev *indio_dev)
{
	struct max1027_state *st = iio_priv(indio_dev);

	st->reg = MAX1027_CONV_REG | MAX1027_SCAN_0_N;
	st->reg |= MAX1027_CHAN(fls(*indio_dev->active_scan_mask) - 2);
	if (*indio_dev->active_scan_mask & MAX1X27_SCAN_MASK_TEMP)
		st->reg |= MAX1027_TEMP;

	return spi_write(st->spi, &st->reg, 1);
}

static int max1027_enable_trigger(struct iio_dev *indio_dev, bool enable)
{
	struct max1027_state *st = iio_priv(indio_dev);

	st->reg = MAX1027_SETUP_REG | MAX1027_REF_MODE2;

	/*
	 * Start acquisition on:
	 * MODE0: external hardware trigger wired to the cnvst input pin
	 * MODE2: conversion register write
	 */
	if (enable)
		st->reg |= MAX1027_CKS_MODE0;
	else
		st->reg |= MAX1027_CKS_MODE2;

	return spi_write(st->spi, &st->reg, 1);
}

static int max1027_read_single_value(struct iio_dev *indio_dev,
				     struct iio_chan_spec const *chan,
				     int *val)
{
	int ret;
	struct max1027_state *st = iio_priv(indio_dev);

	ret = iio_device_claim_direct_mode(indio_dev);
	if (ret)
		return ret;

	/* Configure conversion register with the requested chan */
	st->reg = MAX1027_CONV_REG | MAX1027_CHAN(chan->channel) |
		  MAX1027_NOSCAN;
	if (chan->type == IIO_TEMP)
		st->reg |= MAX1027_TEMP;
	ret = spi_write(st->spi, &st->reg, 1);
	if (ret < 0) {
		dev_err(&indio_dev->dev,
			"Failed to configure conversion register\n");
		goto release;
	}

	/*
	 * For an unknown reason, when we use the mode "10" (write
	 * conversion register), the interrupt doesn't occur every time.
	 * So we just wait the maximum conversion time and deliver the value.
	 */
	ret = max1027_wait_eoc(indio_dev);
	if (ret)
		goto release;

	/* Read result */
	ret = spi_read(st->spi, st->buffer, (chan->type == IIO_TEMP) ? 4 : 2);

release:
	iio_device_release_direct_mode(indio_dev);

	if (ret < 0)
		return ret;

	*val = be16_to_cpu(st->buffer[0]);

	return IIO_VAL_INT;
}

static int max1027_read_raw(struct iio_dev *indio_dev,
			    struct iio_chan_spec const *chan,
			    int *val, int *val2, long mask)
{
	int ret = 0;
	struct max1027_state *st = iio_priv(indio_dev);

	mutex_lock(&st->lock);

	switch (mask) {
	case IIO_CHAN_INFO_RAW:
		ret = max1027_read_single_value(indio_dev, chan, val);
		break;
	case IIO_CHAN_INFO_SCALE:
		switch (chan->type) {
		case IIO_TEMP:
			*val = 1;
			*val2 = 8;
			ret = IIO_VAL_FRACTIONAL;
			break;
		case IIO_VOLTAGE:
			*val = 2500;
			*val2 = chan->scan_type.realbits;
			ret = IIO_VAL_FRACTIONAL_LOG2;
			break;
		default:
			ret = -EINVAL;
			break;
		}
		break;
	default:
		ret = -EINVAL;
		break;
	}

	mutex_unlock(&st->lock);

	return ret;
}

static int max1027_debugfs_reg_access(struct iio_dev *indio_dev,
				      unsigned int reg, unsigned int writeval,
				      unsigned int *readval)
{
	struct max1027_state *st = iio_priv(indio_dev);
	u8 *val = (u8 *)st->buffer;

	if (readval) {
		int ret = spi_read(st->spi, val, 2);
		*readval = be16_to_cpu(st->buffer[0]);
		return ret;
	}

	*val = (u8)writeval;
	return spi_write(st->spi, val, 1);
}

static int max1027_set_cnvst_trigger_state(struct iio_trigger *trig, bool state)
{
	struct iio_dev *indio_dev = iio_trigger_get_drvdata(trig);
	int ret;

	/*
	 * In order to disable the convst trigger, start acquisition on
	 * conversion register write, which basically disables triggering
	 * conversions upon cnvst changes and thus has the effect of disabling
	 * the external hardware trigger.
	 */
	ret = max1027_enable_trigger(indio_dev, state);
	if (ret)
		return ret;

	if (state) {
		ret = max1027_configure_chans_and_start(indio_dev);
		if (ret)
			return ret;
	}

	return 0;
}

static int max1027_read_scan(struct iio_dev *indio_dev)
{
	struct max1027_state *st = iio_priv(indio_dev);
	unsigned int scanned_chans;
	int ret;

	scanned_chans = fls(*indio_dev->active_scan_mask) - 1;
	if (*indio_dev->active_scan_mask & MAX1X27_SCAN_MASK_TEMP)
		scanned_chans++;

	/* fill buffer with all channel */
	ret = spi_read(st->spi, st->buffer, scanned_chans * 2);
	if (ret < 0)
		return ret;

	iio_push_to_buffers(indio_dev, st->buffer);

	return 0;
}

static irqreturn_t max1027_handler(int irq, void *private)
{
	struct iio_dev *indio_dev = private;
	struct max1027_state *st = iio_priv(indio_dev);

	/*
	 * If buffers are disabled (raw read) or when using external triggers,
	 * we just need to unlock the waiters which will then handle the data.
	 *
	 * When using the internal trigger, we must hand-off the choice of the
	 * handler to the core which will then lookup through the interrupt tree
	 * for the right handler registered with iio_triggered_buffer_setup()
	 * to execute, as this trigger might very well be used in conjunction
	 * with another device. The core will then call the relevant handler to
	 * perform the data processing step.
	 */
	if (!iio_buffer_enabled(indio_dev))
		complete(&st->complete);
	else
		iio_trigger_poll(indio_dev->trig);

	return IRQ_HANDLED;
}

static irqreturn_t max1027_trigger_handler(int irq, void *private)
{
	struct iio_poll_func *pf = private;
	struct iio_dev *indio_dev = pf->indio_dev;
	int ret;

	if (!iio_trigger_using_own(indio_dev)) {
		ret = max1027_configure_chans_and_start(indio_dev);
		if (ret)
			goto out;

		/* This is a threaded handler, it is fine to wait for an IRQ */
		ret = max1027_wait_eoc(indio_dev);
		if (ret)
			goto out;
	}

	ret = max1027_read_scan(indio_dev);
out:
	if (ret)
		dev_err(&indio_dev->dev,
			"Cannot read scanned values (%d)\n", ret);

	iio_trigger_notify_done(indio_dev->trig);

	return IRQ_HANDLED;
}

static const struct iio_trigger_ops max1027_trigger_ops = {
	.validate_device = &iio_trigger_validate_own_device,
	.set_trigger_state = &max1027_set_cnvst_trigger_state,
};

static const struct iio_info max1027_info = {
	.read_raw = &max1027_read_raw,
	.debugfs_reg_access = &max1027_debugfs_reg_access,
};

static int max1027_probe(struct spi_device *spi)
{
	int ret;
	struct iio_dev *indio_dev;
	struct max1027_state *st;

	indio_dev = devm_iio_device_alloc(&spi->dev, sizeof(*st));
	if (!indio_dev) {
		pr_err("Can't allocate iio device\n");
		return -ENOMEM;
	}

	st = iio_priv(indio_dev);
	st->spi = spi;
	st->info = &max1027_chip_info_tbl[spi_get_device_id(spi)->driver_data];

	mutex_init(&st->lock);
	init_completion(&st->complete);

	indio_dev->name = spi_get_device_id(spi)->name;
	indio_dev->info = &max1027_info;
	indio_dev->modes = INDIO_DIRECT_MODE;
	indio_dev->channels = st->info->channels;
	indio_dev->num_channels = st->info->num_channels;
	indio_dev->available_scan_masks = st->info->available_scan_masks;

	st->buffer = devm_kmalloc_array(&indio_dev->dev,
					indio_dev->num_channels, 2,
					GFP_KERNEL);
	if (!st->buffer)
		return -ENOMEM;

	/* Enable triggered buffers */
	ret = devm_iio_triggered_buffer_setup(&spi->dev, indio_dev,
					      &iio_pollfunc_store_time,
					      &max1027_trigger_handler,
					      NULL);
	if (ret < 0) {
		dev_err(&indio_dev->dev, "Failed to setup buffer\n");
		return ret;
	}

	/* If there is an EOC interrupt, register the cnvst hardware trigger */
	if (spi->irq) {
		st->trig = devm_iio_trigger_alloc(&spi->dev, "%s-trigger",
						  indio_dev->name);
		if (!st->trig) {
			ret = -ENOMEM;
			dev_err(&indio_dev->dev,
				"Failed to allocate iio trigger\n");
			return ret;
		}

		st->trig->ops = &max1027_trigger_ops;
		iio_trigger_set_drvdata(st->trig, indio_dev);
		ret = devm_iio_trigger_register(&indio_dev->dev,
						st->trig);
		if (ret < 0) {
			dev_err(&indio_dev->dev,
				"Failed to register iio trigger\n");
			return ret;
		}

		ret = devm_request_irq(&spi->dev, spi->irq, max1027_handler,
				       IRQF_TRIGGER_FALLING,
				       spi->dev.driver->name, indio_dev);
		if (ret < 0) {
			dev_err(&indio_dev->dev, "Failed to allocate IRQ.\n");
			return ret;
		}
	}

	/* Internal reset */
	st->reg = MAX1027_RST_REG;
	ret = spi_write(st->spi, &st->reg, 1);
	if (ret < 0) {
		dev_err(&indio_dev->dev, "Failed to reset the ADC\n");
		return ret;
	}

	/* Disable averaging */
	st->reg = MAX1027_AVG_REG;
	ret = spi_write(st->spi, &st->reg, 1);
	if (ret < 0) {
		dev_err(&indio_dev->dev, "Failed to configure averaging register\n");
		return ret;
	}

	/* Assume conversion on register write for now */
	ret = max1027_enable_trigger(indio_dev, false);
	if (ret)
		return ret;

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

static struct spi_driver max1027_driver = {
	.driver = {
		.name	= "max1027",
		.of_match_table = max1027_adc_dt_ids,
	},
	.probe		= max1027_probe,
	.id_table	= max1027_id,
};
module_spi_driver(max1027_driver);

MODULE_AUTHOR("Philippe Reynes <tremyfr@yahoo.fr>");
MODULE_DESCRIPTION("MAX1X27/MAX1X29/MAX1X31 ADC");
MODULE_LICENSE("GPL v2");