IIO: Add basic MXS LRADC driver

This driver is very basic. It supports userland trigger, buffer and
raw access to channels. The support for delay channels is missing
altogether.
Signed-off-by: Marek Vasut <marex@denx.de>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>
Cc: Jonathan Cameron <jic23@kernel.org>
Cc: Juergen Beisert <jbe@pengutronix.de>
Cc: Lars-Peter Clausen <lars@metafoo.de>
Cc: Shawn Guo <shawn.guo@linaro.org>
Cc: Wolfgang Denk <wd@denx.de>

Documentation/devicetree/bindings/staging/iio/adc/mxs-lradc.txt

+* Freescale i.MX28 LRADC device driver
+
+Required properties:
+- compatible: Should be "fsl,imx28-lradc"
+- reg: Address and length of the register set for the device
+- interrupts: Should contain the LRADC interrupts
+
+Examples:
+
+	lradc@80050000 {
+		compatible = "fsl,imx28-lradc";
+		reg = <0x80050000 0x2000>;
+		interrupts = <10 14 15 16 17 18 19
+				20 21 22 23 24 25>;
+	};

drivers/staging/iio/adc/Kconfig

@@ -200,6 +200,18 @@ config LPC32XX_ADC
 	  activate only one via device tree selection.  Provides direct access
 	  via sysfs.
 
+config MXS_LRADC
+	tristate "Freescale i.MX28 LRADC"
+	depends on ARCH_MXS
+	select IIO_BUFFER
+	select IIO_TRIGGERED_BUFFER
+	help
+	  Say yes here to build support for i.MX28 LRADC convertor
+	  built into these chips.
+
+	  To compile this driver as a module, choose M here: the
+	  module will be called mxs-lradc.
+
 config SPEAR_ADC
 	tristate "ST SPEAr ADC"
 	depends on PLAT_SPEAR

drivers/staging/iio/adc/Makefile

@@ -38,4 +38,5 @@ obj-$(CONFIG_ADT7310) += adt7310.o
 obj-$(CONFIG_ADT7410) += adt7410.o
 obj-$(CONFIG_AD7280) += ad7280a.o
 obj-$(CONFIG_LPC32XX_ADC) += lpc32xx_adc.o
+obj-$(CONFIG_MXS_LRADC) += mxs-lradc.o
 obj-$(CONFIG_SPEAR_ADC) += spear_adc.o

drivers/staging/iio/adc/mxs-lradc.c

+/*
+ * Freescale i.MX28 LRADC driver
+ *
+ * Copyright (c) 2012 DENX Software Engineering, GmbH.
+ * Marek Vasut <marex@denx.de>
+ *
+ * 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/interrupt.h>
+#include <linux/device.h>
+#include <linux/kernel.h>
+#include <linux/slab.h>
+#include <linux/of.h>
+#include <linux/of_device.h>
+#include <linux/sysfs.h>
+#include <linux/list.h>
+#include <linux/io.h>
+#include <linux/module.h>
+#include <linux/platform_device.h>
+#include <linux/spinlock.h>
+#include <linux/wait.h>
+#include <linux/sched.h>
+#include <linux/stmp_device.h>
+#include <linux/bitops.h>
+#include <linux/completion.h>
+
+#include <mach/mxs.h>
+#include <mach/common.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 DRIVER_NAME		"mxs-lradc"
+
+#define LRADC_MAX_DELAY_CHANS	4
+#define LRADC_MAX_MAPPED_CHANS	8
+#define LRADC_MAX_TOTAL_CHANS	16
+
+#define LRADC_DELAY_TIMER_HZ	2000
+
+/*
+ * Make this runtime configurable if necessary. Currently, if the buffered mode
+ * is enabled, the LRADC takes LRADC_DELAY_TIMER_LOOP samples of data before
+ * triggering IRQ. The sampling happens every (LRADC_DELAY_TIMER_PER / 2000)
+ * seconds. The result is that the samples arrive every 500mS.
+ */
+#define LRADC_DELAY_TIMER_PER	200
+#define LRADC_DELAY_TIMER_LOOP	5
+
+static const char * const mxs_lradc_irq_name[] = {
+	"mxs-lradc-touchscreen",
+	"mxs-lradc-thresh0",
+	"mxs-lradc-thresh1",
+	"mxs-lradc-channel0",
+	"mxs-lradc-channel1",
+	"mxs-lradc-channel2",
+	"mxs-lradc-channel3",
+	"mxs-lradc-channel4",
+	"mxs-lradc-channel5",
+	"mxs-lradc-channel6",
+	"mxs-lradc-channel7",
+	"mxs-lradc-button0",
+	"mxs-lradc-button1",
+};
+
+struct mxs_lradc_chan {
+	uint8_t				slot;
+	uint8_t				flags;
+};
+
+struct mxs_lradc {
+	struct device		*dev;
+	void __iomem		*base;
+	int			irq[13];
+
+	uint32_t		*buffer;
+	struct iio_trigger	*trig;
+
+	struct mutex		lock;
+
+	uint8_t			enable;
+
+	struct completion	completion;
+};
+
+#define	LRADC_CTRL0				0x00
+#define LRADC_CTRL0_TOUCH_DETECT_ENABLE		(1 << 23)
+#define LRADC_CTRL0_TOUCH_SCREEN_TYPE		(1 << 22)
+
+#define	LRADC_CTRL1				0x10
+#define	LRADC_CTRL1_LRADC_IRQ(n)		(1 << (n))
+#define	LRADC_CTRL1_LRADC_IRQ_MASK		0x1fff
+#define	LRADC_CTRL1_LRADC_IRQ_EN(n)		(1 << ((n) + 16))
+#define	LRADC_CTRL1_LRADC_IRQ_EN_MASK		(0x1fff << 16)
+
+#define	LRADC_CTRL2				0x20
+#define	LRADC_CTRL2_TEMPSENSE_PWD		(1 << 15)
+
+#define	LRADC_CH(n)				(0x50 + (0x10 * (n)))
+#define	LRADC_CH_ACCUMULATE			(1 << 29)
+#define	LRADC_CH_NUM_SAMPLES_MASK		(0x1f << 24)
+#define	LRADC_CH_NUM_SAMPLES_OFFSET		24
+#define	LRADC_CH_VALUE_MASK			0x3ffff
+#define	LRADC_CH_VALUE_OFFSET			0
+
+#define	LRADC_DELAY(n)				(0xd0 + (0x10 * (n)))
+#define	LRADC_DELAY_TRIGGER_LRADCS_MASK		(0xff << 24)
+#define	LRADC_DELAY_TRIGGER_LRADCS_OFFSET	24
+#define	LRADC_DELAY_KICK			(1 << 20)
+#define	LRADC_DELAY_TRIGGER_DELAYS_MASK		(0xf << 16)
+#define	LRADC_DELAY_TRIGGER_DELAYS_OFFSET	16
+#define	LRADC_DELAY_LOOP_COUNT_MASK		(0x1f << 11)
+#define	LRADC_DELAY_LOOP_COUNT_OFFSET		11
+#define	LRADC_DELAY_DELAY_MASK			0x7ff
+#define	LRADC_DELAY_DELAY_OFFSET		0
+
+#define	LRADC_CTRL4				0x140
+#define	LRADC_CTRL4_LRADCSELECT_MASK(n)		(0xf << ((n) * 4))
+#define	LRADC_CTRL4_LRADCSELECT_OFFSET(n)	((n) * 4)
+
+/*
+ * Raw I/O operations
+ */
+static int mxs_lradc_read_raw(struct iio_dev *iio_dev,
+			const struct iio_chan_spec *chan,
+			int *val, int *val2, long m)
+{
+	struct mxs_lradc *lradc = iio_priv(iio_dev);
+	int ret;
+
+	if (m != IIO_CHAN_INFO_RAW)
+		return -EINVAL;
+
+	/* Check for invalid channel */
+	if (chan->channel > LRADC_MAX_TOTAL_CHANS)
+		return -EINVAL;
+
+	/*
+	 * See if there is no buffered operation in progess. If there is, simply
+	 * bail out. This can be improved to support both buffered and raw IO at
+	 * the same time, yet the code becomes horribly complicated. Therefore I
+	 * applied KISS principle here.
+	 */
+	ret = mutex_trylock(&lradc->lock);
+	if (!ret)
+		return -EBUSY;
+
+	INIT_COMPLETION(lradc->completion);
+
+	/*
+	 * No buffered operation in progress, map the channel and trigger it.
+	 * Virtual channel 0 is always used here as the others are always not
+	 * used if doing raw sampling.
+	 */
+	writel(LRADC_CTRL1_LRADC_IRQ_EN_MASK,
+		lradc->base + LRADC_CTRL1 + STMP_OFFSET_REG_CLR);
+	writel(0xff, lradc->base + LRADC_CTRL0 + STMP_OFFSET_REG_CLR);
+
+	writel(chan->channel, lradc->base + LRADC_CTRL4);
+	writel(0, lradc->base + LRADC_CH(0));
+
+	/* Enable the IRQ and start sampling the channel. */
+	writel(LRADC_CTRL1_LRADC_IRQ_EN(0),
+		lradc->base + LRADC_CTRL1 + STMP_OFFSET_REG_SET);
+	writel(1 << 0, lradc->base + LRADC_CTRL0 + STMP_OFFSET_REG_SET);
+
+	/* Wait for completion on the channel, 1 second max. */
+	ret = wait_for_completion_killable_timeout(&lradc->completion, HZ);
+	if (!ret)
+		ret = -ETIMEDOUT;
+	if (ret < 0)
+		goto err;
+
+	/* Read the data. */
+	*val = readl(lradc->base + LRADC_CH(0)) & LRADC_CH_VALUE_MASK;
+	ret = IIO_VAL_INT;
+
+err:
+	writel(LRADC_CTRL1_LRADC_IRQ_EN(0),
+		lradc->base + LRADC_CTRL1 + STMP_OFFSET_REG_CLR);
+
+	mutex_unlock(&lradc->lock);
+
+	return ret;
+}
+
+static const struct iio_info mxs_lradc_iio_info = {
+	.driver_module		= THIS_MODULE,
+	.read_raw		= mxs_lradc_read_raw,
+};
+
+/*
+ * IRQ Handling
+ */
+static irqreturn_t mxs_lradc_handle_irq(int irq, void *data)
+{
+	struct iio_dev *iio = data;
+	struct mxs_lradc *lradc = iio_priv(iio);
+	unsigned long reg = readl(lradc->base + LRADC_CTRL1);
+
+	if (!(reg & LRADC_CTRL1_LRADC_IRQ_MASK))
+		return IRQ_NONE;
+
+	/*
+	 * Touchscreen IRQ handling code shall probably have priority
+	 * and therefore shall be placed here.
+	 */
+
+	if (iio_buffer_enabled(iio))
+		iio_trigger_poll(iio->trig, iio_get_time_ns());
+	else if (reg & LRADC_CTRL1_LRADC_IRQ(0))
+		complete(&lradc->completion);
+
+	writel(reg & LRADC_CTRL1_LRADC_IRQ_MASK,
+		lradc->base + LRADC_CTRL1 + STMP_OFFSET_REG_CLR);
+
+	return IRQ_HANDLED;
+}
+
+/*
+ * Trigger handling
+ */
+static irqreturn_t mxs_lradc_trigger_handler(int irq, void *p)
+{
+	struct iio_poll_func *pf = p;
+	struct iio_dev *iio = pf->indio_dev;
+	struct mxs_lradc *lradc = iio_priv(iio);
+	struct iio_buffer *buffer = iio->buffer;
+	const uint32_t chan_value = LRADC_CH_ACCUMULATE |
+		((LRADC_DELAY_TIMER_LOOP - 1) << LRADC_CH_NUM_SAMPLES_OFFSET);
+	int i, j = 0;
+
+	for_each_set_bit(i, iio->active_scan_mask, iio->masklength) {
+		lradc->buffer[j] = readl(lradc->base + LRADC_CH(j));
+		writel(chan_value, lradc->base + LRADC_CH(j));
+		lradc->buffer[j] &= LRADC_CH_VALUE_MASK;
+		lradc->buffer[j] /= LRADC_DELAY_TIMER_LOOP;
+		j++;
+	}
+
+	if (iio->scan_timestamp) {
+		s64 *timestamp = (s64 *)((u8 *)lradc->buffer +
+					ALIGN(j, sizeof(s64)));
+		*timestamp = pf->timestamp;
+	}
+
+	iio_push_to_buffer(buffer, (u8 *)lradc->buffer, pf->timestamp);
+
+	iio_trigger_notify_done(iio->trig);
+
+	return IRQ_HANDLED;
+}
+
+static int mxs_lradc_configure_trigger(struct iio_trigger *trig, bool state)
+{
+	struct iio_dev *iio = trig->private_data;
+	struct mxs_lradc *lradc = iio_priv(iio);
+	const uint32_t st = state ? STMP_OFFSET_REG_SET : STMP_OFFSET_REG_CLR;
+
+	writel(LRADC_DELAY_KICK, lradc->base + LRADC_DELAY(0) + st);
+
+	return 0;
+}
+
+static const struct iio_trigger_ops mxs_lradc_trigger_ops = {
+	.owner = THIS_MODULE,
+	.set_trigger_state = &mxs_lradc_configure_trigger,
+};
+
+static int mxs_lradc_trigger_init(struct iio_dev *iio)
+{
+	int ret;
+	struct iio_trigger *trig;
+
+	trig = iio_trigger_alloc("%s-dev%i", iio->name, iio->id);
+	if (trig == NULL)
+		return -ENOMEM;
+
+	trig->dev.parent = iio->dev.parent;
+	trig->private_data = iio;
+	trig->ops = &mxs_lradc_trigger_ops;
+
+	ret = iio_trigger_register(trig);
+	if (ret) {
+		iio_trigger_free(trig);
+		return ret;
+	}
+
+	iio->trig = trig;
+
+	return 0;
+}
+
+static void mxs_lradc_trigger_remove(struct iio_dev *iio)
+{
+	iio_trigger_unregister(iio->trig);
+	iio_trigger_free(iio->trig);
+}
+
+static int mxs_lradc_buffer_preenable(struct iio_dev *iio)
+{
+	struct mxs_lradc *lradc = iio_priv(iio);
+	struct iio_buffer *buffer = iio->buffer;
+	int ret = 0, chan, ofs = 0, enable = 0;
+	uint32_t ctrl4 = 0;
+	uint32_t ctrl1_irq = 0;
+	const uint32_t chan_value = LRADC_CH_ACCUMULATE |
+		((LRADC_DELAY_TIMER_LOOP - 1) << LRADC_CH_NUM_SAMPLES_OFFSET);
+	const int len = bitmap_weight(buffer->scan_mask, LRADC_MAX_TOTAL_CHANS);
+
+	if (!len)
+		return -EINVAL;
+
+	/*
+	 * Lock the driver so raw access can not be done during buffered
+	 * operation. This simplifies the code a lot.
+	 */
+	ret = mutex_trylock(&lradc->lock);
+	if (!ret)
+		return -EBUSY;
+
+	lradc->buffer = kmalloc(len * sizeof(*lradc->buffer), GFP_KERNEL);
+	if (!lradc->buffer) {
+		ret = -ENOMEM;
+		goto err_mem;
+	}
+
+	ret = iio_sw_buffer_preenable(iio);
+	if (ret < 0)
+		goto err_buf;
+
+	writel(LRADC_CTRL1_LRADC_IRQ_EN_MASK,
+		lradc->base + LRADC_CTRL1 + STMP_OFFSET_REG_CLR);
+	writel(0xff, lradc->base + LRADC_CTRL0 + STMP_OFFSET_REG_CLR);
+
+	for_each_set_bit(chan, buffer->scan_mask, LRADC_MAX_TOTAL_CHANS) {
+		ctrl4 |= chan << LRADC_CTRL4_LRADCSELECT_OFFSET(ofs);
+		ctrl1_irq |= LRADC_CTRL1_LRADC_IRQ_EN(ofs);
+		writel(chan_value, lradc->base + LRADC_CH(ofs));
+		enable |= 1 << ofs;
+		ofs++;
+	};
+
+	writel(LRADC_DELAY_TRIGGER_LRADCS_MASK | LRADC_DELAY_KICK,
+		lradc->base + LRADC_DELAY(0) + STMP_OFFSET_REG_CLR);
+
+	writel(ctrl4, lradc->base + LRADC_CTRL4);
+	writel(ctrl1_irq, lradc->base + LRADC_CTRL1 + STMP_OFFSET_REG_SET);
+
+	writel(enable << LRADC_DELAY_TRIGGER_LRADCS_OFFSET,
+		lradc->base + LRADC_DELAY(0) + STMP_OFFSET_REG_SET);
+
+	return 0;
+
+err_buf:
+	kfree(lradc->buffer);
+err_mem:
+	mutex_unlock(&lradc->lock);
+	return ret;
+}
+
+static int mxs_lradc_buffer_postdisable(struct iio_dev *iio)
+{
+	struct mxs_lradc *lradc = iio_priv(iio);
+
+	writel(LRADC_DELAY_TRIGGER_LRADCS_MASK | LRADC_DELAY_KICK,
+		lradc->base + LRADC_DELAY(0) + STMP_OFFSET_REG_CLR);
+
+	writel(0xff, lradc->base + LRADC_CTRL0 + STMP_OFFSET_REG_CLR);
+	writel(LRADC_CTRL1_LRADC_IRQ_EN_MASK,
+		lradc->base + LRADC_CTRL1 + STMP_OFFSET_REG_CLR);
+
+	kfree(lradc->buffer);
+	mutex_unlock(&lradc->lock);
+
+	return 0;
+}
+
+static bool mxs_lradc_validate_scan_mask(struct iio_dev *iio,
+					const unsigned long *mask)
+{
+	const int mw = bitmap_weight(mask, iio->masklength);
+
+	return mw <= LRADC_MAX_MAPPED_CHANS;
+}
+
+static const struct iio_buffer_setup_ops mxs_lradc_buffer_ops = {
+	.preenable = &mxs_lradc_buffer_preenable,
+	.postenable = &iio_triggered_buffer_postenable,
+	.predisable = &iio_triggered_buffer_predisable,
+	.postdisable = &mxs_lradc_buffer_postdisable,
+	.validate_scan_mask = &mxs_lradc_validate_scan_mask,
+};
+
+/*
+ * Driver initialization
+ */
+
+#define MXS_ADC_CHAN(idx, chan_type) {				\
+	.type = (chan_type),					\
+	.indexed = 1,						\
+	.scan_index = (idx),					\
+	.info_mask = IIO_CHAN_INFO_RAW_SEPARATE_BIT,		\
+	.channel = (idx),					\
+	.scan_type = {						\
+		.sign = 'u',					\
+		.realbits = 18,					\
+		.storagebits = 32,				\
+	},							\
+}
+
+static const struct iio_chan_spec mxs_lradc_chan_spec[] = {
+	MXS_ADC_CHAN(0, IIO_VOLTAGE),
+	MXS_ADC_CHAN(1, IIO_VOLTAGE),
+	MXS_ADC_CHAN(2, IIO_VOLTAGE),
+	MXS_ADC_CHAN(3, IIO_VOLTAGE),
+	MXS_ADC_CHAN(4, IIO_VOLTAGE),
+	MXS_ADC_CHAN(5, IIO_VOLTAGE),
+	MXS_ADC_CHAN(6, IIO_VOLTAGE),
+	MXS_ADC_CHAN(7, IIO_VOLTAGE),	/* VBATT */
+	MXS_ADC_CHAN(8, IIO_TEMP),	/* Temp sense 0 */
+	MXS_ADC_CHAN(9, IIO_TEMP),	/* Temp sense 1 */
+	MXS_ADC_CHAN(10, IIO_VOLTAGE),	/* VDDIO */
+	MXS_ADC_CHAN(11, IIO_VOLTAGE),	/* VTH */
+	MXS_ADC_CHAN(12, IIO_VOLTAGE),	/* VDDA */
+	MXS_ADC_CHAN(13, IIO_VOLTAGE),	/* VDDD */
+	MXS_ADC_CHAN(14, IIO_VOLTAGE),	/* VBG */
+	MXS_ADC_CHAN(15, IIO_VOLTAGE),	/* VDD5V */
+};
+
+static void mxs_lradc_hw_init(struct mxs_lradc *lradc)
+{
+	int i;
+	const uint32_t cfg =
+		(LRADC_DELAY_TIMER_PER << LRADC_DELAY_DELAY_OFFSET);
+
+	stmp_reset_block(lradc->base);
+
+	for (i = 0; i < LRADC_MAX_DELAY_CHANS; i++)
+		writel(cfg | (1 << (LRADC_DELAY_TRIGGER_DELAYS_OFFSET + i)),
+			lradc->base + LRADC_DELAY(i));
+
+	/* Start internal temperature sensing. */
+	writel(0, lradc->base + LRADC_CTRL2);
+}
+
+static void mxs_lradc_hw_stop(struct mxs_lradc *lradc)
+{
+	int i;
+
+	writel(LRADC_CTRL1_LRADC_IRQ_EN_MASK,
+		lradc->base + LRADC_CTRL1 + STMP_OFFSET_REG_CLR);
+
+	for (i = 0; i < LRADC_MAX_DELAY_CHANS; i++)
+		writel(0, lradc->base + LRADC_DELAY(i));
+}
+
+static int __devinit mxs_lradc_probe(struct platform_device *pdev)
+{
+	struct device *dev = &pdev->dev;
+	struct mxs_lradc *lradc;
+	struct iio_dev *iio;
+	struct resource *iores;
+	int ret = 0;
+	int i;
+
+	/* Allocate the IIO device. */
+	iio = iio_device_alloc(sizeof(*lradc));
+	if (!iio) {
+		dev_err(dev, "Failed to allocate IIO device\n");
+		return -ENOMEM;
+	}
+
+	lradc = iio_priv(iio);
+
+	/* Grab the memory area */
+	iores = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+	lradc->dev = &pdev->dev;
+	lradc->base = devm_request_and_ioremap(dev, iores);
+	if (!lradc->base) {
+		ret = -EADDRNOTAVAIL;
+		goto err_addr;
+	}
+
+	/* Grab all IRQ sources */
+	for (i = 0; i < 13; i++) {
+		lradc->irq[i] = platform_get_irq(pdev, i);
+		if (lradc->irq[i] < 0) {
+			ret = -EINVAL;
+			goto err_addr;
+		}
+
+		ret = devm_request_irq(dev, lradc->irq[i],
+					mxs_lradc_handle_irq, 0,
+					mxs_lradc_irq_name[i], iio);
+		if (ret)
+			goto err_addr;
+	}
+
+	platform_set_drvdata(pdev, iio);
+
+	init_completion(&lradc->completion);
+	mutex_init(&lradc->lock);
+
+	iio->name = pdev->name;
+	iio->dev.parent = &pdev->dev;
+	iio->info = &mxs_lradc_iio_info;
+	iio->modes = INDIO_DIRECT_MODE;
+	iio->channels = mxs_lradc_chan_spec;
+	iio->num_channels = ARRAY_SIZE(mxs_lradc_chan_spec);
+
+	ret = iio_triggered_buffer_setup(iio, &iio_pollfunc_store_time,
+				&mxs_lradc_trigger_handler,
+				&mxs_lradc_buffer_ops);
+	if (ret)
+		goto err_addr;
+
+	ret = mxs_lradc_trigger_init(iio);
+	if (ret)
+		goto err_trig;
+
+	/* Register IIO device. */
+	ret = iio_device_register(iio);
+	if (ret) {
+		dev_err(dev, "Failed to register IIO device\n");
+		goto err_dev;
+	}
+
+	/* Configure the hardware. */
+	mxs_lradc_hw_init(lradc);
+
+	return 0;
+
+err_dev:
+	mxs_lradc_trigger_remove(iio);
+err_trig:
+	iio_triggered_buffer_cleanup(iio);
+err_addr:
+	iio_device_free(iio);
+	return ret;
+}
+
+static int __devexit mxs_lradc_remove(struct platform_device *pdev)
+{
+	struct iio_dev *iio = platform_get_drvdata(pdev);
+	struct mxs_lradc *lradc = iio_priv(iio);
+
+	mxs_lradc_hw_stop(lradc);
+
+	iio_device_unregister(iio);
+	iio_triggered_buffer_cleanup(iio);
+	mxs_lradc_trigger_remove(iio);
+	iio_device_free(iio);
+
+	return 0;
+}
+
+static const struct of_device_id mxs_lradc_dt_ids[] = {
+	{ .compatible = "fsl,imx28-lradc", },
+	{ /* sentinel */ }
+};
+MODULE_DEVICE_TABLE(of, mxs_lradc_dt_ids);
+
+static struct platform_driver mxs_lradc_driver = {
+	.driver	= {
+		.name	= DRIVER_NAME,
+		.owner	= THIS_MODULE,
+		.of_match_table = mxs_lradc_dt_ids,
+	},
+	.probe	= mxs_lradc_probe,
+	.remove	= __devexit_p(mxs_lradc_remove),
+};
+
+module_platform_driver(mxs_lradc_driver);
+
+MODULE_AUTHOR("Marek Vasut <marex@denx.de>");
+MODULE_DESCRIPTION("Freescale i.MX28 LRADC driver");
+MODULE_LICENSE("GPL v2");