iio: adc: mxs-lradc: Add support for ADC driver

Add support for sixteen-channel 12-bit resolution ADC and its functions,
which include general-purpose ADC readings, battery voltage measurement,
and die temperature measurement.
Signed-off-by: NKsenija Stanojevic <ksenija.stanojevic@gmail.com>
Reviewed-by: NJonathan Cameron <jic23@kernel.org>
Reviewed-by: NMarek Vasut <marex@denx.de>
Signed-off-by: NLee Jones <lee.jones@linaro.org>

drivers/iio/adc/Kconfig

@@ -229,6 +229,19 @@ config EXYNOS_ADC
 	  To compile this driver as a module, choose M here: the module will be
 	  called exynos_adc.
 
+config MXS_LRADC_ADC
+	tristate "Freescale i.MX23/i.MX28 LRADC ADC"
+	depends on MFD_MXS_LRADC
+	select IIO_BUFFER
+	select IIO_TRIGGERED_BUFFER
+	help
+	  Say yes here to build support for the ADC functions of the
+	  i.MX23/i.MX28 LRADC. This includes general-purpose ADC readings,
+	  battery voltage measurement, and die temperature measurement.
+
+	  This driver can also be built as a module. If so, the module will be
+	  called mxs-lradc-adc.
+
 config FSL_MX25_ADC
 	tristate "Freescale MX25 ADC driver"
 	depends on MFD_MX25_TSADC

drivers/iio/adc/Makefile

@@ -39,6 +39,7 @@ obj-$(CONFIG_MCP3422) += mcp3422.o
 obj-$(CONFIG_MEDIATEK_MT6577_AUXADC) += mt6577_auxadc.o
 obj-$(CONFIG_MEN_Z188_ADC) += men_z188_adc.o
 obj-$(CONFIG_MESON_SARADC) += meson_saradc.o
+obj-$(CONFIG_MXS_LRADC_ADC) += mxs-lradc-adc.o
 obj-$(CONFIG_MXS_LRADC) += mxs-lradc.o
 obj-$(CONFIG_NAU7802) += nau7802.o
 obj-$(CONFIG_PALMAS_GPADC) += palmas_gpadc.o

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

+/*
+ * Freescale MXS LRADC ADC driver
+ *
+ * Copyright (c) 2012 DENX Software Engineering, GmbH.
+ * Copyright (c) 2017 Ksenija Stanojevic <ksenija.stanojevic@gmail.com>
+ *
+ * Authors:
+ *  Marek Vasut <marex@denx.de>
+ *  Ksenija Stanojevic <ksenija.stanojevic@gmail.com>
+ *
+ * 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/completion.h>
+#include <linux/device.h>
+#include <linux/err.h>
+#include <linux/interrupt.h>
+#include <linux/mfd/core.h>
+#include <linux/mfd/mxs-lradc.h>
+#include <linux/module.h>
+#include <linux/of_irq.h>
+#include <linux/platform_device.h>
+#include <linux/sysfs.h>
+
+#include <linux/iio/buffer.h>
+#include <linux/iio/iio.h>
+#include <linux/iio/trigger.h>
+#include <linux/iio/trigger_consumer.h>
+#include <linux/iio/triggered_buffer.h>
+#include <linux/iio/sysfs.h>
+
+/*
+ * 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
+
+#define VREF_MV_BASE 1850
+
+const char *mx23_lradc_adc_irq_names[] = {
+	"mxs-lradc-channel0",
+	"mxs-lradc-channel1",
+	"mxs-lradc-channel2",
+	"mxs-lradc-channel3",
+	"mxs-lradc-channel4",
+	"mxs-lradc-channel5",
+};
+
+const char *mx28_lradc_adc_irq_names[] = {
+	"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-button0",
+	"mxs-lradc-button1",
+};
+
+static const u32 mxs_lradc_adc_vref_mv[][LRADC_MAX_TOTAL_CHANS] = {
+	[IMX23_LRADC] = {
+		VREF_MV_BASE,		/* CH0 */
+		VREF_MV_BASE,		/* CH1 */
+		VREF_MV_BASE,		/* CH2 */
+		VREF_MV_BASE,		/* CH3 */
+		VREF_MV_BASE,		/* CH4 */
+		VREF_MV_BASE,		/* CH5 */
+		VREF_MV_BASE * 2,	/* CH6 VDDIO */
+		VREF_MV_BASE * 4,	/* CH7 VBATT */
+		VREF_MV_BASE,		/* CH8 Temp sense 0 */
+		VREF_MV_BASE,		/* CH9 Temp sense 1 */
+		VREF_MV_BASE,		/* CH10 */
+		VREF_MV_BASE,		/* CH11 */
+		VREF_MV_BASE,		/* CH12 USB_DP */
+		VREF_MV_BASE,		/* CH13 USB_DN */
+		VREF_MV_BASE,		/* CH14 VBG */
+		VREF_MV_BASE * 4,	/* CH15 VDD5V */
+	},
+	[IMX28_LRADC] = {
+		VREF_MV_BASE,		/* CH0 */
+		VREF_MV_BASE,		/* CH1 */
+		VREF_MV_BASE,		/* CH2 */
+		VREF_MV_BASE,		/* CH3 */
+		VREF_MV_BASE,		/* CH4 */
+		VREF_MV_BASE,		/* CH5 */
+		VREF_MV_BASE,		/* CH6 */
+		VREF_MV_BASE * 4,	/* CH7 VBATT */
+		VREF_MV_BASE,		/* CH8 Temp sense 0 */
+		VREF_MV_BASE,		/* CH9 Temp sense 1 */
+		VREF_MV_BASE * 2,	/* CH10 VDDIO */
+		VREF_MV_BASE,		/* CH11 VTH */
+		VREF_MV_BASE * 2,	/* CH12 VDDA */
+		VREF_MV_BASE,		/* CH13 VDDD */
+		VREF_MV_BASE,		/* CH14 VBG */
+		VREF_MV_BASE * 4,	/* CH15 VDD5V */
+	},
+};
+
+enum mxs_lradc_divbytwo {
+	MXS_LRADC_DIV_DISABLED = 0,
+	MXS_LRADC_DIV_ENABLED,
+};
+
+struct mxs_lradc_scale {
+	unsigned int		integer;
+	unsigned int		nano;
+};
+
+struct mxs_lradc_adc {
+	struct mxs_lradc	*lradc;
+	struct device		*dev;
+
+	void __iomem		*base;
+	u32			buffer[10];
+	struct iio_trigger	*trig;
+	struct completion	completion;
+	spinlock_t		lock;
+
+	const u32		*vref_mv;
+	struct mxs_lradc_scale	scale_avail[LRADC_MAX_TOTAL_CHANS][2];
+	unsigned long		is_divided;
+};
+
+
+/* Raw I/O operations */
+static int mxs_lradc_adc_read_single(struct iio_dev *iio_dev, int chan,
+				     int *val)
+{
+	struct mxs_lradc_adc *adc = iio_priv(iio_dev);
+	struct mxs_lradc *lradc = adc->lradc;
+	int ret;
+
+	/*
+	 * See if there is no buffered operation in progress. 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 = iio_device_claim_direct_mode(iio_dev);
+	if (ret)
+		return ret;
+
+	reinit_completion(&adc->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.
+	 */
+	if (lradc->soc == IMX28_LRADC)
+		writel(LRADC_CTRL1_LRADC_IRQ_EN(0),
+		       adc->base + LRADC_CTRL1 + STMP_OFFSET_REG_CLR);
+	writel(0x1, adc->base + LRADC_CTRL0 + STMP_OFFSET_REG_CLR);
+
+	/* Enable / disable the divider per requirement */
+	if (test_bit(chan, &adc->is_divided))
+		writel(1 << LRADC_CTRL2_DIVIDE_BY_TWO_OFFSET,
+		       adc->base + LRADC_CTRL2 + STMP_OFFSET_REG_SET);
+	else
+		writel(1 << LRADC_CTRL2_DIVIDE_BY_TWO_OFFSET,
+		       adc->base + LRADC_CTRL2 + STMP_OFFSET_REG_CLR);
+
+	/* Clean the slot's previous content, then set new one. */
+	writel(LRADC_CTRL4_LRADCSELECT_MASK(0),
+	       adc->base + LRADC_CTRL4 + STMP_OFFSET_REG_CLR);
+	writel(chan, adc->base + LRADC_CTRL4 + STMP_OFFSET_REG_SET);
+
+	writel(0, adc->base + LRADC_CH(0));
+
+	/* Enable the IRQ and start sampling the channel. */
+	writel(LRADC_CTRL1_LRADC_IRQ_EN(0),
+	       adc->base + LRADC_CTRL1 + STMP_OFFSET_REG_SET);
+	writel(BIT(0), adc->base + LRADC_CTRL0 + STMP_OFFSET_REG_SET);
+
+	/* Wait for completion on the channel, 1 second max. */
+	ret = wait_for_completion_killable_timeout(&adc->completion, HZ);
+	if (!ret)
+		ret = -ETIMEDOUT;
+	if (ret < 0)
+		goto err;
+
+	/* Read the data. */
+	*val = readl(adc->base + LRADC_CH(0)) & LRADC_CH_VALUE_MASK;
+	ret = IIO_VAL_INT;
+
+err:
+	writel(LRADC_CTRL1_LRADC_IRQ_EN(0),
+	       adc->base + LRADC_CTRL1 + STMP_OFFSET_REG_CLR);
+
+	iio_device_release_direct_mode(iio_dev);
+
+	return ret;
+}
+
+static int mxs_lradc_adc_read_temp(struct iio_dev *iio_dev, int *val)
+{
+	int ret, min, max;
+
+	ret = mxs_lradc_adc_read_single(iio_dev, 8, &min);
+	if (ret != IIO_VAL_INT)
+		return ret;
+
+	ret = mxs_lradc_adc_read_single(iio_dev, 9, &max);
+	if (ret != IIO_VAL_INT)
+		return ret;
+
+	*val = max - min;
+
+	return IIO_VAL_INT;
+}
+
+static int mxs_lradc_adc_read_raw(struct iio_dev *iio_dev,
+			      const struct iio_chan_spec *chan,
+			      int *val, int *val2, long m)
+{
+	struct mxs_lradc_adc *adc = iio_priv(iio_dev);
+
+	switch (m) {
+	case IIO_CHAN_INFO_RAW:
+		if (chan->type == IIO_TEMP)
+			return mxs_lradc_adc_read_temp(iio_dev, val);
+
+		return mxs_lradc_adc_read_single(iio_dev, chan->channel, val);
+
+	case IIO_CHAN_INFO_SCALE:
+		if (chan->type == IIO_TEMP) {
+			/*
+			 * From the datasheet, we have to multiply by 1.012 and
+			 * divide by 4
+			 */
+			*val = 0;
+			*val2 = 253000;
+			return IIO_VAL_INT_PLUS_MICRO;
+		}
+
+		*val = adc->vref_mv[chan->channel];
+		*val2 = chan->scan_type.realbits -
+			test_bit(chan->channel, &adc->is_divided);
+		return IIO_VAL_FRACTIONAL_LOG2;
+
+	case IIO_CHAN_INFO_OFFSET:
+		if (chan->type == IIO_TEMP) {
+			/*
+			 * The calculated value from the ADC is in Kelvin, we
+			 * want Celsius for hwmon so the offset is -273.15
+			 * The offset is applied before scaling so it is
+			 * actually -213.15 * 4 / 1.012 = -1079.644268
+			 */
+			*val = -1079;
+			*val2 = 644268;
+
+			return IIO_VAL_INT_PLUS_MICRO;
+		}
+
+		return -EINVAL;
+
+	default:
+		break;
+	}
+
+	return -EINVAL;
+}
+
+static int mxs_lradc_adc_write_raw(struct iio_dev *iio_dev,
+				   const struct iio_chan_spec *chan,
+				   int val, int val2, long m)
+{
+	struct mxs_lradc_adc *adc = iio_priv(iio_dev);
+	struct mxs_lradc_scale *scale_avail =
+			adc->scale_avail[chan->channel];
+	int ret;
+
+	ret = iio_device_claim_direct_mode(iio_dev);
+	if (ret)
+		return ret;
+
+	switch (m) {
+	case IIO_CHAN_INFO_SCALE:
+		ret = -EINVAL;
+		if (val == scale_avail[MXS_LRADC_DIV_DISABLED].integer &&
+		    val2 == scale_avail[MXS_LRADC_DIV_DISABLED].nano) {
+			/* divider by two disabled */
+			clear_bit(chan->channel, &adc->is_divided);
+			ret = 0;
+		} else if (val == scale_avail[MXS_LRADC_DIV_ENABLED].integer &&
+			   val2 == scale_avail[MXS_LRADC_DIV_ENABLED].nano) {
+			/* divider by two enabled */
+			set_bit(chan->channel, &adc->is_divided);
+			ret = 0;
+		}
+
+		break;
+	default:
+		ret = -EINVAL;
+		break;
+	}
+
+	iio_device_release_direct_mode(iio_dev);
+
+	return ret;
+}
+
+static int mxs_lradc_adc_write_raw_get_fmt(struct iio_dev *iio_dev,
+					   const struct iio_chan_spec *chan,
+					   long m)
+{
+	return IIO_VAL_INT_PLUS_NANO;
+}
+
+static ssize_t mxs_lradc_adc_show_scale_avail(struct device *dev,
+						 struct device_attribute *attr,
+						 char *buf)
+{
+	struct iio_dev *iio = dev_to_iio_dev(dev);
+	struct mxs_lradc_adc *adc = iio_priv(iio);
+	struct iio_dev_attr *iio_attr = to_iio_dev_attr(attr);
+	int i, ch, len = 0;
+
+	ch = iio_attr->address;
+	for (i = 0; i < ARRAY_SIZE(adc->scale_avail[ch]); i++)
+		len += sprintf(buf + len, "%u.%09u ",
+			       adc->scale_avail[ch][i].integer,
+			       adc->scale_avail[ch][i].nano);
+
+	len += sprintf(buf + len, "\n");
+
+	return len;
+}
+
+#define SHOW_SCALE_AVAILABLE_ATTR(ch)\
+	IIO_DEVICE_ATTR(in_voltage##ch##_scale_available, 0444,\
+			mxs_lradc_adc_show_scale_avail, NULL, ch)
+
+SHOW_SCALE_AVAILABLE_ATTR(0);
+SHOW_SCALE_AVAILABLE_ATTR(1);
+SHOW_SCALE_AVAILABLE_ATTR(2);
+SHOW_SCALE_AVAILABLE_ATTR(3);
+SHOW_SCALE_AVAILABLE_ATTR(4);
+SHOW_SCALE_AVAILABLE_ATTR(5);
+SHOW_SCALE_AVAILABLE_ATTR(6);
+SHOW_SCALE_AVAILABLE_ATTR(7);
+SHOW_SCALE_AVAILABLE_ATTR(10);
+SHOW_SCALE_AVAILABLE_ATTR(11);
+SHOW_SCALE_AVAILABLE_ATTR(12);
+SHOW_SCALE_AVAILABLE_ATTR(13);
+SHOW_SCALE_AVAILABLE_ATTR(14);
+SHOW_SCALE_AVAILABLE_ATTR(15);
+
+static struct attribute *mxs_lradc_adc_attributes[] = {
+	&iio_dev_attr_in_voltage0_scale_available.dev_attr.attr,
+	&iio_dev_attr_in_voltage1_scale_available.dev_attr.attr,
+	&iio_dev_attr_in_voltage2_scale_available.dev_attr.attr,
+	&iio_dev_attr_in_voltage3_scale_available.dev_attr.attr,
+	&iio_dev_attr_in_voltage4_scale_available.dev_attr.attr,
+	&iio_dev_attr_in_voltage5_scale_available.dev_attr.attr,
+	&iio_dev_attr_in_voltage6_scale_available.dev_attr.attr,
+	&iio_dev_attr_in_voltage7_scale_available.dev_attr.attr,
+	&iio_dev_attr_in_voltage10_scale_available.dev_attr.attr,
+	&iio_dev_attr_in_voltage11_scale_available.dev_attr.attr,
+	&iio_dev_attr_in_voltage12_scale_available.dev_attr.attr,
+	&iio_dev_attr_in_voltage13_scale_available.dev_attr.attr,
+	&iio_dev_attr_in_voltage14_scale_available.dev_attr.attr,
+	&iio_dev_attr_in_voltage15_scale_available.dev_attr.attr,
+	NULL
+};
+
+static const struct attribute_group mxs_lradc_adc_attribute_group = {
+	.attrs = mxs_lradc_adc_attributes,
+};
+
+static const struct iio_info mxs_lradc_adc_iio_info = {
+	.driver_module		= THIS_MODULE,
+	.read_raw		= mxs_lradc_adc_read_raw,
+	.write_raw		= mxs_lradc_adc_write_raw,
+	.write_raw_get_fmt	= mxs_lradc_adc_write_raw_get_fmt,
+	.attrs			= &mxs_lradc_adc_attribute_group,
+};
+
+/* IRQ Handling */
+static irqreturn_t mxs_lradc_adc_handle_irq(int irq, void *data)
+{
+	struct iio_dev *iio = data;
+	struct mxs_lradc_adc *adc = iio_priv(iio);
+	struct mxs_lradc *lradc = adc->lradc;
+	unsigned long reg = readl(adc->base + LRADC_CTRL1);
+	unsigned long flags;
+
+	if (!(reg & mxs_lradc_irq_mask(lradc)))
+		return IRQ_NONE;
+
+	if (iio_buffer_enabled(iio)) {
+		if (reg & lradc->buffer_vchans) {
+			spin_lock_irqsave(&adc->lock, flags);
+			iio_trigger_poll(iio->trig);
+			spin_unlock_irqrestore(&adc->lock, flags);
+		}
+	} else if (reg & LRADC_CTRL1_LRADC_IRQ(0)) {
+		complete(&adc->completion);
+	}
+
+	writel(reg & mxs_lradc_irq_mask(lradc),
+	       adc->base + LRADC_CTRL1 + STMP_OFFSET_REG_CLR);
+
+	return IRQ_HANDLED;
+}
+
+
+/* Trigger handling */
+static irqreturn_t mxs_lradc_adc_trigger_handler(int irq, void *p)
+{
+	struct iio_poll_func *pf = p;
+	struct iio_dev *iio = pf->indio_dev;
+	struct mxs_lradc_adc *adc = iio_priv(iio);
+	const u32 chan_value = LRADC_CH_ACCUMULATE |
+		((LRADC_DELAY_TIMER_LOOP - 1) << LRADC_CH_NUM_SAMPLES_OFFSET);
+	unsigned int i, j = 0;
+
+	for_each_set_bit(i, iio->active_scan_mask, LRADC_MAX_TOTAL_CHANS) {
+		adc->buffer[j] = readl(adc->base + LRADC_CH(j));
+		writel(chan_value, adc->base + LRADC_CH(j));
+		adc->buffer[j] &= LRADC_CH_VALUE_MASK;
+		adc->buffer[j] /= LRADC_DELAY_TIMER_LOOP;
+		j++;
+	}
+
+	iio_push_to_buffers_with_timestamp(iio, adc->buffer, pf->timestamp);
+
+	iio_trigger_notify_done(iio->trig);
+
+	return IRQ_HANDLED;
+}
+
+static int mxs_lradc_adc_configure_trigger(struct iio_trigger *trig, bool state)
+{
+	struct iio_dev *iio = iio_trigger_get_drvdata(trig);
+	struct mxs_lradc_adc *adc = iio_priv(iio);
+	const u32 st = state ? STMP_OFFSET_REG_SET : STMP_OFFSET_REG_CLR;
+
+	writel(LRADC_DELAY_KICK, adc->base + (LRADC_DELAY(0) + st));
+
+	return 0;
+}
+
+static const struct iio_trigger_ops mxs_lradc_adc_trigger_ops = {
+	.owner = THIS_MODULE,
+	.set_trigger_state = &mxs_lradc_adc_configure_trigger,
+};
+
+static int mxs_lradc_adc_trigger_init(struct iio_dev *iio)
+{
+	int ret;
+	struct iio_trigger *trig;
+	struct mxs_lradc_adc *adc = iio_priv(iio);
+
+	trig = devm_iio_trigger_alloc(&iio->dev, "%s-dev%i", iio->name,
+				      iio->id);
+
+	trig->dev.parent = adc->dev;
+	iio_trigger_set_drvdata(trig, iio);
+	trig->ops = &mxs_lradc_adc_trigger_ops;
+
+	ret = iio_trigger_register(trig);
+	if (ret)
+		return ret;
+
+	adc->trig = trig;
+
+	return 0;
+}
+
+static void mxs_lradc_adc_trigger_remove(struct iio_dev *iio)
+{
+	struct mxs_lradc_adc *adc = iio_priv(iio);
+
+	iio_trigger_unregister(adc->trig);
+}
+
+static int mxs_lradc_adc_buffer_preenable(struct iio_dev *iio)
+{
+	struct mxs_lradc_adc *adc = iio_priv(iio);
+	struct mxs_lradc *lradc = adc->lradc;
+	int chan, ofs = 0;
+	unsigned long enable = 0;
+	u32 ctrl4_set = 0;
+	u32 ctrl4_clr = 0;
+	u32 ctrl1_irq = 0;
+	const u32 chan_value = LRADC_CH_ACCUMULATE |
+		((LRADC_DELAY_TIMER_LOOP - 1) << LRADC_CH_NUM_SAMPLES_OFFSET);
+
+	if (lradc->soc == IMX28_LRADC)
+		writel(lradc->buffer_vchans << LRADC_CTRL1_LRADC_IRQ_EN_OFFSET,
+		       adc->base + LRADC_CTRL1 + STMP_OFFSET_REG_CLR);
+	writel(lradc->buffer_vchans,
+	       adc->base + LRADC_CTRL0 + STMP_OFFSET_REG_CLR);
+
+	for_each_set_bit(chan, iio->active_scan_mask, LRADC_MAX_TOTAL_CHANS) {
+		ctrl4_set |= chan << LRADC_CTRL4_LRADCSELECT_OFFSET(ofs);
+		ctrl4_clr |= LRADC_CTRL4_LRADCSELECT_MASK(ofs);
+		ctrl1_irq |= LRADC_CTRL1_LRADC_IRQ_EN(ofs);
+		writel(chan_value, adc->base + LRADC_CH(ofs));
+		bitmap_set(&enable, ofs, 1);
+		ofs++;
+	}
+
+	writel(LRADC_DELAY_TRIGGER_LRADCS_MASK | LRADC_DELAY_KICK,
+	       adc->base + LRADC_DELAY(0) + STMP_OFFSET_REG_CLR);
+	writel(ctrl4_clr, adc->base + LRADC_CTRL4 + STMP_OFFSET_REG_CLR);
+	writel(ctrl4_set, adc->base + LRADC_CTRL4 + STMP_OFFSET_REG_SET);
+	writel(ctrl1_irq, adc->base + LRADC_CTRL1 + STMP_OFFSET_REG_SET);
+	writel(enable << LRADC_DELAY_TRIGGER_LRADCS_OFFSET,
+	       adc->base + LRADC_DELAY(0) + STMP_OFFSET_REG_SET);
+
+	return 0;
+}
+
+static int mxs_lradc_adc_buffer_postdisable(struct iio_dev *iio)
+{
+	struct mxs_lradc_adc *adc = iio_priv(iio);
+	struct mxs_lradc *lradc = adc->lradc;
+
+	writel(LRADC_DELAY_TRIGGER_LRADCS_MASK | LRADC_DELAY_KICK,
+	       adc->base + LRADC_DELAY(0) + STMP_OFFSET_REG_CLR);
+
+	writel(lradc->buffer_vchans,
+	       adc->base + LRADC_CTRL0 + STMP_OFFSET_REG_CLR);
+	if (lradc->soc == IMX28_LRADC)
+		writel(lradc->buffer_vchans << LRADC_CTRL1_LRADC_IRQ_EN_OFFSET,
+		       adc->base + LRADC_CTRL1 + STMP_OFFSET_REG_CLR);
+
+	return 0;
+}
+
+static bool mxs_lradc_adc_validate_scan_mask(struct iio_dev *iio,
+					     const unsigned long *mask)
+{
+	struct mxs_lradc_adc *adc = iio_priv(iio);
+	struct mxs_lradc *lradc = adc->lradc;
+	const int map_chans = bitmap_weight(mask, LRADC_MAX_TOTAL_CHANS);
+	int rsvd_chans = 0;
+	unsigned long rsvd_mask = 0;
+
+	if (lradc->use_touchbutton)
+		rsvd_mask |= CHAN_MASK_TOUCHBUTTON;
+	if (lradc->touchscreen_wire == MXS_LRADC_TOUCHSCREEN_4WIRE)
+		rsvd_mask |= CHAN_MASK_TOUCHSCREEN_4WIRE;
+	if (lradc->touchscreen_wire == MXS_LRADC_TOUCHSCREEN_5WIRE)
+		rsvd_mask |= CHAN_MASK_TOUCHSCREEN_5WIRE;
+
+	if (lradc->use_touchbutton)
+		rsvd_chans++;
+	if (lradc->touchscreen_wire)
+		rsvd_chans += 2;
+
+	/* Test for attempts to map channels with special mode of operation. */
+	if (bitmap_intersects(mask, &rsvd_mask, LRADC_MAX_TOTAL_CHANS))
+		return false;
+
+	/* Test for attempts to map more channels then available slots. */
+	if (map_chans + rsvd_chans > LRADC_MAX_MAPPED_CHANS)
+		return false;
+
+	return true;
+}
+
+static const struct iio_buffer_setup_ops mxs_lradc_adc_buffer_ops = {
+	.preenable = &mxs_lradc_adc_buffer_preenable,
+	.postenable = &iio_triggered_buffer_postenable,
+	.predisable = &iio_triggered_buffer_predisable,
+	.postdisable = &mxs_lradc_adc_buffer_postdisable,
+	.validate_scan_mask = &mxs_lradc_adc_validate_scan_mask,
+};
+
+/* Driver initialization */
+#define MXS_ADC_CHAN(idx, chan_type, name) {			\
+	.type = (chan_type),					\
+	.indexed = 1,						\
+	.scan_index = (idx),					\
+	.info_mask_separate = BIT(IIO_CHAN_INFO_RAW) |		\
+			      BIT(IIO_CHAN_INFO_SCALE),		\
+	.channel = (idx),					\
+	.address = (idx),					\
+	.scan_type = {						\
+		.sign = 'u',					\
+		.realbits = LRADC_RESOLUTION,			\
+		.storagebits = 32,				\
+	},							\
+	.datasheet_name = (name),				\
+}
+
+static const struct iio_chan_spec mx23_lradc_chan_spec[] = {
+	MXS_ADC_CHAN(0, IIO_VOLTAGE, "LRADC0"),
+	MXS_ADC_CHAN(1, IIO_VOLTAGE, "LRADC1"),
+	MXS_ADC_CHAN(2, IIO_VOLTAGE, "LRADC2"),
+	MXS_ADC_CHAN(3, IIO_VOLTAGE, "LRADC3"),
+	MXS_ADC_CHAN(4, IIO_VOLTAGE, "LRADC4"),
+	MXS_ADC_CHAN(5, IIO_VOLTAGE, "LRADC5"),
+	MXS_ADC_CHAN(6, IIO_VOLTAGE, "VDDIO"),
+	MXS_ADC_CHAN(7, IIO_VOLTAGE, "VBATT"),
+	/* Combined Temperature sensors */
+	{
+		.type = IIO_TEMP,
+		.indexed = 1,
+		.scan_index = 8,
+		.info_mask_separate = BIT(IIO_CHAN_INFO_RAW) |
+				      BIT(IIO_CHAN_INFO_OFFSET) |
+				      BIT(IIO_CHAN_INFO_SCALE),
+		.channel = 8,
+		.scan_type = {.sign = 'u', .realbits = 18, .storagebits = 32,},
+		.datasheet_name = "TEMP_DIE",
+	},
+	/* Hidden channel to keep indexes */
+	{
+		.type = IIO_TEMP,
+		.indexed = 1,
+		.scan_index = -1,
+		.channel = 9,
+	},
+	MXS_ADC_CHAN(10, IIO_VOLTAGE, NULL),
+	MXS_ADC_CHAN(11, IIO_VOLTAGE, NULL),
+	MXS_ADC_CHAN(12, IIO_VOLTAGE, "USB_DP"),
+	MXS_ADC_CHAN(13, IIO_VOLTAGE, "USB_DN"),
+	MXS_ADC_CHAN(14, IIO_VOLTAGE, "VBG"),
+	MXS_ADC_CHAN(15, IIO_VOLTAGE, "VDD5V"),
+};
+
+static const struct iio_chan_spec mx28_lradc_chan_spec[] = {
+	MXS_ADC_CHAN(0, IIO_VOLTAGE, "LRADC0"),
+	MXS_ADC_CHAN(1, IIO_VOLTAGE, "LRADC1"),
+	MXS_ADC_CHAN(2, IIO_VOLTAGE, "LRADC2"),
+	MXS_ADC_CHAN(3, IIO_VOLTAGE, "LRADC3"),
+	MXS_ADC_CHAN(4, IIO_VOLTAGE, "LRADC4"),
+	MXS_ADC_CHAN(5, IIO_VOLTAGE, "LRADC5"),
+	MXS_ADC_CHAN(6, IIO_VOLTAGE, "LRADC6"),
+	MXS_ADC_CHAN(7, IIO_VOLTAGE, "VBATT"),
+	/* Combined Temperature sensors */
+	{
+		.type = IIO_TEMP,
+		.indexed = 1,
+		.scan_index = 8,
+		.info_mask_separate = BIT(IIO_CHAN_INFO_RAW) |
+				      BIT(IIO_CHAN_INFO_OFFSET) |
+				      BIT(IIO_CHAN_INFO_SCALE),
+		.channel = 8,
+		.scan_type = {.sign = 'u', .realbits = 18, .storagebits = 32,},
+		.datasheet_name = "TEMP_DIE",
+	},
+	/* Hidden channel to keep indexes */
+	{
+		.type = IIO_TEMP,
+		.indexed = 1,
+		.scan_index = -1,
+		.channel = 9,
+	},
+	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_adc_hw_init(struct mxs_lradc_adc *adc)
+{
+	/* The ADC always uses DELAY CHANNEL 0. */
+	const u32 adc_cfg =
+		(1 << (LRADC_DELAY_TRIGGER_DELAYS_OFFSET + 0)) |
+		(LRADC_DELAY_TIMER_PER << LRADC_DELAY_DELAY_OFFSET);
+
+	/* Configure DELAY CHANNEL 0 for generic ADC sampling. */
+	writel(adc_cfg, adc->base + LRADC_DELAY(0));
+
+	/*
+	 * Start internal temperature sensing by clearing bit
+	 * HW_LRADC_CTRL2_TEMPSENSE_PWD. This bit can be left cleared
+	 * after power up.
+	 */
+	writel(0, adc->base + LRADC_CTRL2);
+}
+
+static void mxs_lradc_adc_hw_stop(struct mxs_lradc_adc *adc)
+{
+	writel(0, adc->base + LRADC_DELAY(0));
+}
+
+static int mxs_lradc_adc_probe(struct platform_device *pdev)
+{
+	struct device *dev = &pdev->dev;
+	struct mxs_lradc *lradc = dev_get_drvdata(dev->parent);
+	struct mxs_lradc_adc *adc;
+	struct iio_dev *iio;
+	struct resource *iores;
+	int ret, irq, virq, i, s, n;
+	u64 scale_uv;
+	const char **irq_name;
+
+	/* Allocate the IIO device. */
+	iio = devm_iio_device_alloc(dev, sizeof(*adc));
+	if (!iio) {
+		dev_err(dev, "Failed to allocate IIO device\n");
+		return -ENOMEM;
+	}
+
+	adc = iio_priv(iio);
+	adc->lradc = lradc;
+	adc->dev = dev;
+
+	iores = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+	adc->base = devm_ioremap(dev, iores->start, resource_size(iores));
+	if (IS_ERR(adc->base))
+		return PTR_ERR(adc->base);
+
+	init_completion(&adc->completion);
+	spin_lock_init(&adc->lock);
+
+	platform_set_drvdata(pdev, iio);
+
+	iio->name = pdev->name;
+	iio->dev.parent = dev;
+	iio->dev.of_node = dev->parent->of_node;
+	iio->info = &mxs_lradc_adc_iio_info;
+	iio->modes = INDIO_DIRECT_MODE;
+	iio->masklength = LRADC_MAX_TOTAL_CHANS;
+
+	if (lradc->soc == IMX23_LRADC) {
+		iio->channels = mx23_lradc_chan_spec;
+		iio->num_channels = ARRAY_SIZE(mx23_lradc_chan_spec);
+		irq_name = mx23_lradc_adc_irq_names;
+		n = ARRAY_SIZE(mx23_lradc_adc_irq_names);
+	} else {
+		iio->channels = mx28_lradc_chan_spec;
+		iio->num_channels = ARRAY_SIZE(mx28_lradc_chan_spec);
+		irq_name = mx28_lradc_adc_irq_names;
+		n = ARRAY_SIZE(mx28_lradc_adc_irq_names);
+	}
+
+	ret = stmp_reset_block(adc->base);
+	if (ret)
+		return ret;
+
+	for (i = 0; i < n; i++) {
+		irq = platform_get_irq_byname(pdev, irq_name[i]);
+		if (irq < 0)
+			return irq;
+
+		virq = irq_of_parse_and_map(dev->parent->of_node, irq);
+
+		ret = devm_request_irq(dev, virq, mxs_lradc_adc_handle_irq,
+				       0, irq_name[i], iio);
+		if (ret)
+			return ret;
+	}
+
+	ret = mxs_lradc_adc_trigger_init(iio);
+	if (ret)
+		goto err_trig;
+
+	ret = iio_triggered_buffer_setup(iio, &iio_pollfunc_store_time,
+					 &mxs_lradc_adc_trigger_handler,
+					 &mxs_lradc_adc_buffer_ops);
+	if (ret)
+		return ret;
+
+	adc->vref_mv = mxs_lradc_adc_vref_mv[lradc->soc];
+
+	/* Populate available ADC input ranges */
+	for (i = 0; i < LRADC_MAX_TOTAL_CHANS; i++) {
+		for (s = 0; s < ARRAY_SIZE(adc->scale_avail[i]); s++) {
+			/*
+			 * [s=0] = optional divider by two disabled (default)
+			 * [s=1] = optional divider by two enabled
+			 *
+			 * The scale is calculated by doing:
+			 *   Vref >> (realbits - s)
+			 * which multiplies by two on the second component
+			 * of the array.
+			 */
+			scale_uv = ((u64)adc->vref_mv[i] * 100000000) >>
+				   (LRADC_RESOLUTION - s);
+			adc->scale_avail[i][s].nano =
+					do_div(scale_uv, 100000000) * 10;
+			adc->scale_avail[i][s].integer = scale_uv;
+		}
+	}
+
+	/* Configure the hardware. */
+	mxs_lradc_adc_hw_init(adc);
+
+	/* Register IIO device. */
+	ret = iio_device_register(iio);
+	if (ret) {
+		dev_err(dev, "Failed to register IIO device\n");
+		goto err_dev;
+	}
+
+	return 0;
+
+err_dev:
+	mxs_lradc_adc_hw_stop(adc);
+	mxs_lradc_adc_trigger_remove(iio);
+err_trig:
+	iio_triggered_buffer_cleanup(iio);
+	return ret;
+}
+
+static int mxs_lradc_adc_remove(struct platform_device *pdev)
+{
+	struct iio_dev *iio = platform_get_drvdata(pdev);
+	struct mxs_lradc_adc *adc = iio_priv(iio);
+
+	iio_device_unregister(iio);
+	mxs_lradc_adc_hw_stop(adc);
+	mxs_lradc_adc_trigger_remove(iio);
+	iio_triggered_buffer_cleanup(iio);
+
+	return 0;
+}
+
+static struct platform_driver mxs_lradc_adc_driver = {
+	.driver = {
+		.name	= "mxs-lradc-adc",
+	},
+	.probe	= mxs_lradc_adc_probe,
+	.remove = mxs_lradc_adc_remove,
+};
+module_platform_driver(mxs_lradc_adc_driver);
+
+MODULE_AUTHOR("Marek Vasut <marex@denx.de>");
+MODULE_DESCRIPTION("Freescale MXS LRADC driver general purpose ADC driver");
+MODULE_LICENSE("GPL");
+MODULE_ALIAS("platform:mxs-lradc-adc");