Adding upstream version 4.19.249.upstream/4.19.249upstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 1962 insertions, 0 deletions

diff --git a/drivers/iio/adc/at91-sama5d2_adc.c b/drivers/iio/adc/at91-sama5d2_adc.c
new file mode 100644
index 000000000..129c3adad
--- /dev/null
+++ b/drivers/iio/adc/at91-sama5d2_adc.c
@@ -0,0 +1,1962 @@
+/*
+ * Atmel ADC driver for SAMA5D2 devices and compatible.
+ *
+ * Copyright (C) 2015 Atmel,
+ *               2015 Ludovic Desroches <ludovic.desroches@atmel.com>
+ *
+ * This software is licensed under the terms of the GNU General Public
+ * License version 2, as published by the Free Software Foundation, and
+ * may be copied, distributed, and modified under those terms.
+ *
+ * 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/bitops.h>
+#include <linux/clk.h>
+#include <linux/dma-mapping.h>
+#include <linux/dmaengine.h>
+#include <linux/interrupt.h>
+#include <linux/io.h>
+#include <linux/module.h>
+#include <linux/of_device.h>
+#include <linux/platform_device.h>
+#include <linux/sched.h>
+#include <linux/wait.h>
+#include <linux/iio/iio.h>
+#include <linux/iio/sysfs.h>
+#include <linux/iio/buffer.h>
+#include <linux/iio/trigger.h>
+#include <linux/iio/trigger_consumer.h>
+#include <linux/iio/triggered_buffer.h>
+#include <linux/pinctrl/consumer.h>
+#include <linux/regulator/consumer.h>
+
+/* Control Register */
+#define AT91_SAMA5D2_CR		0x00
+/* Software Reset */
+#define	AT91_SAMA5D2_CR_SWRST		BIT(0)
+/* Start Conversion */
+#define	AT91_SAMA5D2_CR_START		BIT(1)
+/* Touchscreen Calibration */
+#define	AT91_SAMA5D2_CR_TSCALIB		BIT(2)
+/* Comparison Restart */
+#define	AT91_SAMA5D2_CR_CMPRST		BIT(4)
+
+/* Mode Register */
+#define AT91_SAMA5D2_MR		0x04
+/* Trigger Selection */
+#define	AT91_SAMA5D2_MR_TRGSEL(v)	((v) << 1)
+/* ADTRG */
+#define	AT91_SAMA5D2_MR_TRGSEL_TRIG0	0
+/* TIOA0 */
+#define	AT91_SAMA5D2_MR_TRGSEL_TRIG1	1
+/* TIOA1 */
+#define	AT91_SAMA5D2_MR_TRGSEL_TRIG2	2
+/* TIOA2 */
+#define	AT91_SAMA5D2_MR_TRGSEL_TRIG3	3
+/* PWM event line 0 */
+#define	AT91_SAMA5D2_MR_TRGSEL_TRIG4	4
+/* PWM event line 1 */
+#define	AT91_SAMA5D2_MR_TRGSEL_TRIG5	5
+/* TIOA3 */
+#define	AT91_SAMA5D2_MR_TRGSEL_TRIG6	6
+/* RTCOUT0 */
+#define	AT91_SAMA5D2_MR_TRGSEL_TRIG7	7
+/* Sleep Mode */
+#define	AT91_SAMA5D2_MR_SLEEP		BIT(5)
+/* Fast Wake Up */
+#define	AT91_SAMA5D2_MR_FWUP		BIT(6)
+/* Prescaler Rate Selection */
+#define	AT91_SAMA5D2_MR_PRESCAL(v)	((v) << AT91_SAMA5D2_MR_PRESCAL_OFFSET)
+#define	AT91_SAMA5D2_MR_PRESCAL_OFFSET	8
+#define	AT91_SAMA5D2_MR_PRESCAL_MAX	0xff
+#define AT91_SAMA5D2_MR_PRESCAL_MASK	GENMASK(15, 8)
+/* Startup Time */
+#define	AT91_SAMA5D2_MR_STARTUP(v)	((v) << 16)
+#define AT91_SAMA5D2_MR_STARTUP_MASK	GENMASK(19, 16)
+/* Analog Change */
+#define	AT91_SAMA5D2_MR_ANACH		BIT(23)
+/* Tracking Time */
+#define	AT91_SAMA5D2_MR_TRACKTIM(v)	((v) << 24)
+#define	AT91_SAMA5D2_MR_TRACKTIM_MAX	0xff
+/* Transfer Time */
+#define	AT91_SAMA5D2_MR_TRANSFER(v)	((v) << 28)
+#define	AT91_SAMA5D2_MR_TRANSFER_MAX	0x3
+/* Use Sequence Enable */
+#define	AT91_SAMA5D2_MR_USEQ		BIT(31)
+
+/* Channel Sequence Register 1 */
+#define AT91_SAMA5D2_SEQR1	0x08
+/* Channel Sequence Register 2 */
+#define AT91_SAMA5D2_SEQR2	0x0c
+/* Channel Enable Register */
+#define AT91_SAMA5D2_CHER	0x10
+/* Channel Disable Register */
+#define AT91_SAMA5D2_CHDR	0x14
+/* Channel Status Register */
+#define AT91_SAMA5D2_CHSR	0x18
+/* Last Converted Data Register */
+#define AT91_SAMA5D2_LCDR	0x20
+/* Interrupt Enable Register */
+#define AT91_SAMA5D2_IER	0x24
+/* Interrupt Enable Register - TS X measurement ready */
+#define AT91_SAMA5D2_IER_XRDY   BIT(20)
+/* Interrupt Enable Register - TS Y measurement ready */
+#define AT91_SAMA5D2_IER_YRDY   BIT(21)
+/* Interrupt Enable Register - TS pressure measurement ready */
+#define AT91_SAMA5D2_IER_PRDY   BIT(22)
+/* Interrupt Enable Register - general overrun error */
+#define AT91_SAMA5D2_IER_GOVRE BIT(25)
+/* Interrupt Enable Register - Pen detect */
+#define AT91_SAMA5D2_IER_PEN    BIT(29)
+/* Interrupt Enable Register - No pen detect */
+#define AT91_SAMA5D2_IER_NOPEN  BIT(30)
+/* Interrupt Disable Register */
+#define AT91_SAMA5D2_IDR	0x28
+/* Interrupt Mask Register */
+#define AT91_SAMA5D2_IMR	0x2c
+/* Interrupt Status Register */
+#define AT91_SAMA5D2_ISR	0x30
+/* Interrupt Status Register - Pen touching sense status */
+#define AT91_SAMA5D2_ISR_PENS   BIT(31)
+/* Last Channel Trigger Mode Register */
+#define AT91_SAMA5D2_LCTMR	0x34
+/* Last Channel Compare Window Register */
+#define AT91_SAMA5D2_LCCWR	0x38
+/* Overrun Status Register */
+#define AT91_SAMA5D2_OVER	0x3c
+/* Extended Mode Register */
+#define AT91_SAMA5D2_EMR	0x40
+/* Extended Mode Register - Oversampling rate */
+#define AT91_SAMA5D2_EMR_OSR(V)			((V) << 16)
+#define AT91_SAMA5D2_EMR_OSR_MASK		GENMASK(17, 16)
+#define AT91_SAMA5D2_EMR_OSR_1SAMPLES		0
+#define AT91_SAMA5D2_EMR_OSR_4SAMPLES		1
+#define AT91_SAMA5D2_EMR_OSR_16SAMPLES		2
+
+/* Extended Mode Register - Averaging on single trigger event */
+#define AT91_SAMA5D2_EMR_ASTE(V)		((V) << 20)
+/* Compare Window Register */
+#define AT91_SAMA5D2_CWR	0x44
+/* Channel Gain Register */
+#define AT91_SAMA5D2_CGR	0x48
+
+/* Channel Offset Register */
+#define AT91_SAMA5D2_COR	0x4c
+#define AT91_SAMA5D2_COR_DIFF_OFFSET	16
+
+/* Channel Data Register 0 */
+#define AT91_SAMA5D2_CDR0	0x50
+/* Analog Control Register */
+#define AT91_SAMA5D2_ACR	0x94
+/* Analog Control Register - Pen detect sensitivity mask */
+#define AT91_SAMA5D2_ACR_PENDETSENS_MASK        GENMASK(1, 0)
+
+/* Touchscreen Mode Register */
+#define AT91_SAMA5D2_TSMR	0xb0
+/* Touchscreen Mode Register - No touch mode */
+#define AT91_SAMA5D2_TSMR_TSMODE_NONE           0
+/* Touchscreen Mode Register - 4 wire screen, no pressure measurement */
+#define AT91_SAMA5D2_TSMR_TSMODE_4WIRE_NO_PRESS 1
+/* Touchscreen Mode Register - 4 wire screen, pressure measurement */
+#define AT91_SAMA5D2_TSMR_TSMODE_4WIRE_PRESS    2
+/* Touchscreen Mode Register - 5 wire screen */
+#define AT91_SAMA5D2_TSMR_TSMODE_5WIRE          3
+/* Touchscreen Mode Register - Average samples mask */
+#define AT91_SAMA5D2_TSMR_TSAV_MASK             GENMASK(5, 4)
+/* Touchscreen Mode Register - Average samples */
+#define AT91_SAMA5D2_TSMR_TSAV(x)               ((x) << 4)
+/* Touchscreen Mode Register - Touch/trigger frequency ratio mask */
+#define AT91_SAMA5D2_TSMR_TSFREQ_MASK           GENMASK(11, 8)
+/* Touchscreen Mode Register - Touch/trigger frequency ratio */
+#define AT91_SAMA5D2_TSMR_TSFREQ(x)             ((x) << 8)
+/* Touchscreen Mode Register - Pen Debounce Time mask */
+#define AT91_SAMA5D2_TSMR_PENDBC_MASK           GENMASK(31, 28)
+/* Touchscreen Mode Register - Pen Debounce Time */
+#define AT91_SAMA5D2_TSMR_PENDBC(x)            ((x) << 28)
+/* Touchscreen Mode Register - No DMA for touch measurements */
+#define AT91_SAMA5D2_TSMR_NOTSDMA               BIT(22)
+/* Touchscreen Mode Register - Disable pen detection */
+#define AT91_SAMA5D2_TSMR_PENDET_DIS            (0 << 24)
+/* Touchscreen Mode Register - Enable pen detection */
+#define AT91_SAMA5D2_TSMR_PENDET_ENA            BIT(24)
+
+/* Touchscreen X Position Register */
+#define AT91_SAMA5D2_XPOSR	0xb4
+/* Touchscreen Y Position Register */
+#define AT91_SAMA5D2_YPOSR	0xb8
+/* Touchscreen Pressure Register */
+#define AT91_SAMA5D2_PRESSR	0xbc
+/* Trigger Register */
+#define AT91_SAMA5D2_TRGR	0xc0
+/* Mask for TRGMOD field of TRGR register */
+#define AT91_SAMA5D2_TRGR_TRGMOD_MASK GENMASK(2, 0)
+/* No trigger, only software trigger can start conversions */
+#define AT91_SAMA5D2_TRGR_TRGMOD_NO_TRIGGER 0
+/* Trigger Mode external trigger rising edge */
+#define AT91_SAMA5D2_TRGR_TRGMOD_EXT_TRIG_RISE 1
+/* Trigger Mode external trigger falling edge */
+#define AT91_SAMA5D2_TRGR_TRGMOD_EXT_TRIG_FALL 2
+/* Trigger Mode external trigger any edge */
+#define AT91_SAMA5D2_TRGR_TRGMOD_EXT_TRIG_ANY 3
+/* Trigger Mode internal periodic */
+#define AT91_SAMA5D2_TRGR_TRGMOD_PERIODIC 5
+/* Trigger Mode - trigger period mask */
+#define AT91_SAMA5D2_TRGR_TRGPER_MASK           GENMASK(31, 16)
+/* Trigger Mode - trigger period */
+#define AT91_SAMA5D2_TRGR_TRGPER(x)             ((x) << 16)
+
+/* Correction Select Register */
+#define AT91_SAMA5D2_COSR	0xd0
+/* Correction Value Register */
+#define AT91_SAMA5D2_CVR	0xd4
+/* Channel Error Correction Register */
+#define AT91_SAMA5D2_CECR	0xd8
+/* Write Protection Mode Register */
+#define AT91_SAMA5D2_WPMR	0xe4
+/* Write Protection Status Register */
+#define AT91_SAMA5D2_WPSR	0xe8
+/* Version Register */
+#define AT91_SAMA5D2_VERSION	0xfc
+
+#define AT91_SAMA5D2_HW_TRIG_CNT 3
+#define AT91_SAMA5D2_SINGLE_CHAN_CNT 12
+#define AT91_SAMA5D2_DIFF_CHAN_CNT 6
+
+#define AT91_SAMA5D2_TIMESTAMP_CHAN_IDX (AT91_SAMA5D2_SINGLE_CHAN_CNT + \
+					 AT91_SAMA5D2_DIFF_CHAN_CNT + 1)
+
+#define AT91_SAMA5D2_TOUCH_X_CHAN_IDX (AT91_SAMA5D2_SINGLE_CHAN_CNT + \
+					 AT91_SAMA5D2_DIFF_CHAN_CNT * 2)
+#define AT91_SAMA5D2_TOUCH_Y_CHAN_IDX   (AT91_SAMA5D2_TOUCH_X_CHAN_IDX + 1)
+#define AT91_SAMA5D2_TOUCH_P_CHAN_IDX   (AT91_SAMA5D2_TOUCH_Y_CHAN_IDX + 1)
+#define AT91_SAMA5D2_MAX_CHAN_IDX	AT91_SAMA5D2_TOUCH_P_CHAN_IDX
+
+#define AT91_SAMA5D2_TOUCH_SAMPLE_PERIOD_US          2000    /* 2ms */
+#define AT91_SAMA5D2_TOUCH_PEN_DETECT_DEBOUNCE_US    200
+
+#define AT91_SAMA5D2_XYZ_MASK		GENMASK(11, 0)
+
+#define AT91_SAMA5D2_MAX_POS_BITS			12
+
+/*
+ * Maximum number of bytes to hold conversion from all channels
+ * without the timestamp.
+ */
+#define AT91_BUFFER_MAX_CONVERSION_BYTES ((AT91_SAMA5D2_SINGLE_CHAN_CNT + \
+					 AT91_SAMA5D2_DIFF_CHAN_CNT) * 2)
+
+/* This total must also include the timestamp */
+#define AT91_BUFFER_MAX_BYTES (AT91_BUFFER_MAX_CONVERSION_BYTES + 8)
+
+#define AT91_BUFFER_MAX_HWORDS (AT91_BUFFER_MAX_BYTES / 2)
+
+#define AT91_HWFIFO_MAX_SIZE_STR	"128"
+#define AT91_HWFIFO_MAX_SIZE		128
+
+/* Possible values for oversampling ratio */
+#define AT91_OSR_1SAMPLES		1
+#define AT91_OSR_4SAMPLES		4
+#define AT91_OSR_16SAMPLES		16
+
+#define AT91_SAMA5D2_CHAN_SINGLE(num, addr)				\
+	{								\
+		.type = IIO_VOLTAGE,					\
+		.channel = num,						\
+		.address = addr,					\
+		.scan_index = num,					\
+		.scan_type = {						\
+			.sign = 'u',					\
+			.realbits = 14,					\
+			.storagebits = 16,				\
+		},							\
+		.info_mask_separate = BIT(IIO_CHAN_INFO_RAW),		\
+		.info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE),	\
+		.info_mask_shared_by_all = BIT(IIO_CHAN_INFO_SAMP_FREQ)|\
+				BIT(IIO_CHAN_INFO_OVERSAMPLING_RATIO),	\
+		.datasheet_name = "CH"#num,				\
+		.indexed = 1,						\
+	}
+
+#define AT91_SAMA5D2_CHAN_DIFF(num, num2, addr)				\
+	{								\
+		.type = IIO_VOLTAGE,					\
+		.differential = 1,					\
+		.channel = num,						\
+		.channel2 = num2,					\
+		.address = addr,					\
+		.scan_index = num + AT91_SAMA5D2_SINGLE_CHAN_CNT,	\
+		.scan_type = {						\
+			.sign = 's',					\
+			.realbits = 14,					\
+			.storagebits = 16,				\
+		},							\
+		.info_mask_separate = BIT(IIO_CHAN_INFO_RAW),		\
+		.info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE),	\
+		.info_mask_shared_by_all = BIT(IIO_CHAN_INFO_SAMP_FREQ)|\
+				BIT(IIO_CHAN_INFO_OVERSAMPLING_RATIO),	\
+		.datasheet_name = "CH"#num"-CH"#num2,			\
+		.indexed = 1,						\
+	}
+
+#define AT91_SAMA5D2_CHAN_TOUCH(num, name, mod)				\
+	{								\
+		.type = IIO_POSITIONRELATIVE,				\
+		.modified = 1,						\
+		.channel = num,						\
+		.channel2 = mod,					\
+		.scan_index = num,					\
+		.scan_type = {						\
+			.sign = 'u',					\
+			.realbits = 12,					\
+			.storagebits = 16,				\
+		},							\
+		.info_mask_separate = BIT(IIO_CHAN_INFO_RAW),		\
+		.info_mask_shared_by_all = BIT(IIO_CHAN_INFO_SAMP_FREQ)|\
+				BIT(IIO_CHAN_INFO_OVERSAMPLING_RATIO),	\
+		.datasheet_name = name,					\
+	}
+#define AT91_SAMA5D2_CHAN_PRESSURE(num, name)				\
+	{								\
+		.type = IIO_PRESSURE,					\
+		.channel = num,						\
+		.scan_index = num,					\
+		.scan_type = {						\
+			.sign = 'u',					\
+			.realbits = 12,					\
+			.storagebits = 16,				\
+		},							\
+		.info_mask_separate = BIT(IIO_CHAN_INFO_RAW),		\
+		.info_mask_shared_by_all = BIT(IIO_CHAN_INFO_SAMP_FREQ)|\
+				BIT(IIO_CHAN_INFO_OVERSAMPLING_RATIO),	\
+		.datasheet_name = name,					\
+	}
+
+#define at91_adc_readl(st, reg)		readl_relaxed(st->base + reg)
+#define at91_adc_writel(st, reg, val)	writel_relaxed(val, st->base + reg)
+
+struct at91_adc_soc_info {
+	unsigned			startup_time;
+	unsigned			min_sample_rate;
+	unsigned			max_sample_rate;
+};
+
+struct at91_adc_trigger {
+	char				*name;
+	unsigned int			trgmod_value;
+	unsigned int			edge_type;
+	bool				hw_trig;
+};
+
+/**
+ * at91_adc_dma - at91-sama5d2 dma information struct
+ * @dma_chan:		the dma channel acquired
+ * @rx_buf:		dma coherent allocated area
+ * @rx_dma_buf:		dma handler for the buffer
+ * @phys_addr:		physical address of the ADC base register
+ * @buf_idx:		index inside the dma buffer where reading was last done
+ * @rx_buf_sz:		size of buffer used by DMA operation
+ * @watermark:		number of conversions to copy before DMA triggers irq
+ * @dma_ts:		hold the start timestamp of dma operation
+ */
+struct at91_adc_dma {
+	struct dma_chan			*dma_chan;
+	u8				*rx_buf;
+	dma_addr_t			rx_dma_buf;
+	phys_addr_t			phys_addr;
+	int				buf_idx;
+	int				rx_buf_sz;
+	int				watermark;
+	s64				dma_ts;
+};
+
+/**
+ * at91_adc_touch - at91-sama5d2 touchscreen information struct
+ * @sample_period_val:		the value for periodic trigger interval
+ * @touching:			is the pen touching the screen or not
+ * @x_pos:			temporary placeholder for pressure computation
+ * @channels_bitmask:		bitmask with the touchscreen channels enabled
+ * @workq:			workqueue for buffer data pushing
+ */
+struct at91_adc_touch {
+	u16				sample_period_val;
+	bool				touching;
+	u16				x_pos;
+	unsigned long			channels_bitmask;
+	struct work_struct		workq;
+};
+
+struct at91_adc_state {
+	void __iomem			*base;
+	int				irq;
+	struct clk			*per_clk;
+	struct regulator		*reg;
+	struct regulator		*vref;
+	int				vref_uv;
+	unsigned int			current_sample_rate;
+	struct iio_trigger		*trig;
+	const struct at91_adc_trigger	*selected_trig;
+	const struct iio_chan_spec	*chan;
+	bool				conversion_done;
+	u32				conversion_value;
+	unsigned int			oversampling_ratio;
+	struct at91_adc_soc_info	soc_info;
+	wait_queue_head_t		wq_data_available;
+	struct at91_adc_dma		dma_st;
+	struct at91_adc_touch		touch_st;
+	u16				buffer[AT91_BUFFER_MAX_HWORDS];
+	/*
+	 * lock to prevent concurrent 'single conversion' requests through
+	 * sysfs.
+	 */
+	struct mutex			lock;
+};
+
+static const struct at91_adc_trigger at91_adc_trigger_list[] = {
+	{
+		.name = "external_rising",
+		.trgmod_value = AT91_SAMA5D2_TRGR_TRGMOD_EXT_TRIG_RISE,
+		.edge_type = IRQ_TYPE_EDGE_RISING,
+		.hw_trig = true,
+	},
+	{
+		.name = "external_falling",
+		.trgmod_value = AT91_SAMA5D2_TRGR_TRGMOD_EXT_TRIG_FALL,
+		.edge_type = IRQ_TYPE_EDGE_FALLING,
+		.hw_trig = true,
+	},
+	{
+		.name = "external_any",
+		.trgmod_value = AT91_SAMA5D2_TRGR_TRGMOD_EXT_TRIG_ANY,
+		.edge_type = IRQ_TYPE_EDGE_BOTH,
+		.hw_trig = true,
+	},
+	{
+		.name = "software",
+		.trgmod_value = AT91_SAMA5D2_TRGR_TRGMOD_NO_TRIGGER,
+		.edge_type = IRQ_TYPE_NONE,
+		.hw_trig = false,
+	},
+};
+
+static const struct iio_chan_spec at91_adc_channels[] = {
+	AT91_SAMA5D2_CHAN_SINGLE(0, 0x50),
+	AT91_SAMA5D2_CHAN_SINGLE(1, 0x54),
+	AT91_SAMA5D2_CHAN_SINGLE(2, 0x58),
+	AT91_SAMA5D2_CHAN_SINGLE(3, 0x5c),
+	AT91_SAMA5D2_CHAN_SINGLE(4, 0x60),
+	AT91_SAMA5D2_CHAN_SINGLE(5, 0x64),
+	AT91_SAMA5D2_CHAN_SINGLE(6, 0x68),
+	AT91_SAMA5D2_CHAN_SINGLE(7, 0x6c),
+	AT91_SAMA5D2_CHAN_SINGLE(8, 0x70),
+	AT91_SAMA5D2_CHAN_SINGLE(9, 0x74),
+	AT91_SAMA5D2_CHAN_SINGLE(10, 0x78),
+	AT91_SAMA5D2_CHAN_SINGLE(11, 0x7c),
+	AT91_SAMA5D2_CHAN_DIFF(0, 1, 0x50),
+	AT91_SAMA5D2_CHAN_DIFF(2, 3, 0x58),
+	AT91_SAMA5D2_CHAN_DIFF(4, 5, 0x60),
+	AT91_SAMA5D2_CHAN_DIFF(6, 7, 0x68),
+	AT91_SAMA5D2_CHAN_DIFF(8, 9, 0x70),
+	AT91_SAMA5D2_CHAN_DIFF(10, 11, 0x78),
+	IIO_CHAN_SOFT_TIMESTAMP(AT91_SAMA5D2_TIMESTAMP_CHAN_IDX),
+	AT91_SAMA5D2_CHAN_TOUCH(AT91_SAMA5D2_TOUCH_X_CHAN_IDX, "x", IIO_MOD_X),
+	AT91_SAMA5D2_CHAN_TOUCH(AT91_SAMA5D2_TOUCH_Y_CHAN_IDX, "y", IIO_MOD_Y),
+	AT91_SAMA5D2_CHAN_PRESSURE(AT91_SAMA5D2_TOUCH_P_CHAN_IDX, "pressure"),
+};
+
+static int at91_adc_chan_xlate(struct iio_dev *indio_dev, int chan)
+{
+	int i;
+
+	for (i = 0; i < indio_dev->num_channels; i++) {
+		if (indio_dev->channels[i].scan_index == chan)
+			return i;
+	}
+	return -EINVAL;
+}
+
+static inline struct iio_chan_spec const *
+at91_adc_chan_get(struct iio_dev *indio_dev, int chan)
+{
+	int index = at91_adc_chan_xlate(indio_dev, chan);
+
+	if (index < 0)
+		return NULL;
+	return indio_dev->channels + index;
+}
+
+static inline int at91_adc_of_xlate(struct iio_dev *indio_dev,
+				    const struct of_phandle_args *iiospec)
+{
+	return at91_adc_chan_xlate(indio_dev, iiospec->args[0]);
+}
+
+static void at91_adc_config_emr(struct at91_adc_state *st)
+{
+	/* configure the extended mode register */
+	unsigned int emr = at91_adc_readl(st, AT91_SAMA5D2_EMR);
+
+	/* select oversampling per single trigger event */
+	emr |= AT91_SAMA5D2_EMR_ASTE(1);
+
+	/* delete leftover content if it's the case */
+	emr &= ~AT91_SAMA5D2_EMR_OSR_MASK;
+
+	/* select oversampling ratio from configuration */
+	switch (st->oversampling_ratio) {
+	case AT91_OSR_1SAMPLES:
+		emr |= AT91_SAMA5D2_EMR_OSR(AT91_SAMA5D2_EMR_OSR_1SAMPLES) &
+		       AT91_SAMA5D2_EMR_OSR_MASK;
+		break;
+	case AT91_OSR_4SAMPLES:
+		emr |= AT91_SAMA5D2_EMR_OSR(AT91_SAMA5D2_EMR_OSR_4SAMPLES) &
+		       AT91_SAMA5D2_EMR_OSR_MASK;
+		break;
+	case AT91_OSR_16SAMPLES:
+		emr |= AT91_SAMA5D2_EMR_OSR(AT91_SAMA5D2_EMR_OSR_16SAMPLES) &
+		       AT91_SAMA5D2_EMR_OSR_MASK;
+		break;
+	}
+
+	at91_adc_writel(st, AT91_SAMA5D2_EMR, emr);
+}
+
+static int at91_adc_adjust_val_osr(struct at91_adc_state *st, int *val)
+{
+	if (st->oversampling_ratio == AT91_OSR_1SAMPLES) {
+		/*
+		 * in this case we only have 12 bits of real data, but channel
+		 * is registered as 14 bits, so shift left two bits
+		 */
+		*val <<= 2;
+	} else if (st->oversampling_ratio == AT91_OSR_4SAMPLES) {
+		/*
+		 * in this case we have 13 bits of real data, but channel
+		 * is registered as 14 bits, so left shift one bit
+		 */
+		*val <<= 1;
+	}
+
+	return IIO_VAL_INT;
+}
+
+static void at91_adc_adjust_val_osr_array(struct at91_adc_state *st, void *buf,
+					  int len)
+{
+	int i = 0, val;
+	u16 *buf_u16 = (u16 *) buf;
+
+	/*
+	 * We are converting each two bytes (each sample).
+	 * First convert the byte based array to u16, and convert each sample
+	 * separately.
+	 * Each value is two bytes in an array of chars, so to not shift
+	 * more than we need, save the value separately.
+	 * len is in bytes, so divide by two to get number of samples.
+	 */
+	while (i < len / 2) {
+		val = buf_u16[i];
+		at91_adc_adjust_val_osr(st, &val);
+		buf_u16[i] = val;
+		i++;
+	}
+}
+
+static int at91_adc_configure_touch(struct at91_adc_state *st, bool state)
+{
+	u32 clk_khz = st->current_sample_rate / 1000;
+	int i = 0;
+	u16 pendbc;
+	u32 tsmr, acr;
+
+	if (!state) {
+		/* disabling touch IRQs and setting mode to no touch enabled */
+		at91_adc_writel(st, AT91_SAMA5D2_IDR,
+				AT91_SAMA5D2_IER_PEN | AT91_SAMA5D2_IER_NOPEN);
+		at91_adc_writel(st, AT91_SAMA5D2_TSMR, 0);
+		return 0;
+	}
+	/*
+	 * debounce time is in microseconds, we need it in milliseconds to
+	 * multiply with kilohertz, so, divide by 1000, but after the multiply.
+	 * round up to make sure pendbc is at least 1
+	 */
+	pendbc = round_up(AT91_SAMA5D2_TOUCH_PEN_DETECT_DEBOUNCE_US *
+			  clk_khz / 1000, 1);
+
+	/* get the required exponent */
+	while (pendbc >> i++)
+		;
+
+	pendbc = i;
+
+	tsmr = AT91_SAMA5D2_TSMR_TSMODE_4WIRE_PRESS;
+
+	tsmr |= AT91_SAMA5D2_TSMR_TSAV(2) & AT91_SAMA5D2_TSMR_TSAV_MASK;
+	tsmr |= AT91_SAMA5D2_TSMR_PENDBC(pendbc) &
+		AT91_SAMA5D2_TSMR_PENDBC_MASK;
+	tsmr |= AT91_SAMA5D2_TSMR_NOTSDMA;
+	tsmr |= AT91_SAMA5D2_TSMR_PENDET_ENA;
+	tsmr |= AT91_SAMA5D2_TSMR_TSFREQ(2) & AT91_SAMA5D2_TSMR_TSFREQ_MASK;
+
+	at91_adc_writel(st, AT91_SAMA5D2_TSMR, tsmr);
+
+	acr =  at91_adc_readl(st, AT91_SAMA5D2_ACR);
+	acr &= ~AT91_SAMA5D2_ACR_PENDETSENS_MASK;
+	acr |= 0x02 & AT91_SAMA5D2_ACR_PENDETSENS_MASK;
+	at91_adc_writel(st, AT91_SAMA5D2_ACR, acr);
+
+	/* Sample Period Time = (TRGPER + 1) / ADCClock */
+	st->touch_st.sample_period_val =
+				 round_up((AT91_SAMA5D2_TOUCH_SAMPLE_PERIOD_US *
+				 clk_khz / 1000) - 1, 1);
+	/* enable pen detect IRQ */
+	at91_adc_writel(st, AT91_SAMA5D2_IER, AT91_SAMA5D2_IER_PEN);
+
+	return 0;
+}
+
+static u16 at91_adc_touch_pos(struct at91_adc_state *st, int reg)
+{
+	u32 val;
+	u32 scale, result, pos;
+
+	/*
+	 * to obtain the actual position we must divide by scale
+	 * and multiply with max, where
+	 * max = 2^AT91_SAMA5D2_MAX_POS_BITS - 1
+	 */
+	/* first half of register is the x or y, second half is the scale */
+	val = at91_adc_readl(st, reg);
+	if (!val)
+		dev_dbg(&iio_priv_to_dev(st)->dev, "pos is 0\n");
+
+	pos = val & AT91_SAMA5D2_XYZ_MASK;
+	result = (pos << AT91_SAMA5D2_MAX_POS_BITS) - pos;
+	scale = (val >> 16) & AT91_SAMA5D2_XYZ_MASK;
+	if (scale == 0) {
+		dev_err(&iio_priv_to_dev(st)->dev, "scale is 0\n");
+		return 0;
+	}
+	result /= scale;
+
+	return result;
+}
+
+static u16 at91_adc_touch_x_pos(struct at91_adc_state *st)
+{
+	st->touch_st.x_pos = at91_adc_touch_pos(st, AT91_SAMA5D2_XPOSR);
+	return st->touch_st.x_pos;
+}
+
+static u16 at91_adc_touch_y_pos(struct at91_adc_state *st)
+{
+	return at91_adc_touch_pos(st, AT91_SAMA5D2_YPOSR);
+}
+
+static u16 at91_adc_touch_pressure(struct at91_adc_state *st)
+{
+	u32 val;
+	u32 z1, z2;
+	u32 pres;
+	u32 rxp = 1;
+	u32 factor = 1000;
+
+	/* calculate the pressure */
+	val = at91_adc_readl(st, AT91_SAMA5D2_PRESSR);
+	z1 = val & AT91_SAMA5D2_XYZ_MASK;
+	z2 = (val >> 16) & AT91_SAMA5D2_XYZ_MASK;
+
+	if (z1 != 0)
+		pres = rxp * (st->touch_st.x_pos * factor / 1024) *
+			(z2 * factor / z1 - factor) /
+			factor;
+	else
+		pres = 0xFFFF;       /* no pen contact */
+
+	/*
+	 * The pressure from device grows down, minimum is 0xFFFF, maximum 0x0.
+	 * We compute it this way, but let's return it in the expected way,
+	 * growing from 0 to 0xFFFF.
+	 */
+	return 0xFFFF - pres;
+}
+
+static int at91_adc_read_position(struct at91_adc_state *st, int chan, u16 *val)
+{
+	*val = 0;
+	if (!st->touch_st.touching)
+		return -ENODATA;
+	if (chan == AT91_SAMA5D2_TOUCH_X_CHAN_IDX)
+		*val = at91_adc_touch_x_pos(st);
+	else if (chan == AT91_SAMA5D2_TOUCH_Y_CHAN_IDX)
+		*val = at91_adc_touch_y_pos(st);
+	else
+		return -ENODATA;
+
+	return IIO_VAL_INT;
+}
+
+static int at91_adc_read_pressure(struct at91_adc_state *st, int chan, u16 *val)
+{
+	*val = 0;
+	if (!st->touch_st.touching)
+		return -ENODATA;
+	if (chan == AT91_SAMA5D2_TOUCH_P_CHAN_IDX)
+		*val = at91_adc_touch_pressure(st);
+	else
+		return -ENODATA;
+
+	return IIO_VAL_INT;
+}
+
+static int at91_adc_configure_trigger(struct iio_trigger *trig, bool state)
+{
+	struct iio_dev *indio = iio_trigger_get_drvdata(trig);
+	struct at91_adc_state *st = iio_priv(indio);
+	u32 status = at91_adc_readl(st, AT91_SAMA5D2_TRGR);
+	u8 bit;
+
+	/* clear TRGMOD */
+	status &= ~AT91_SAMA5D2_TRGR_TRGMOD_MASK;
+
+	if (state)
+		status |= st->selected_trig->trgmod_value;
+
+	/* set/unset hw trigger */
+	at91_adc_writel(st, AT91_SAMA5D2_TRGR, status);
+
+	for_each_set_bit(bit, indio->active_scan_mask, indio->num_channels) {
+		struct iio_chan_spec const *chan = at91_adc_chan_get(indio, bit);
+		u32 cor;
+
+		if (!chan)
+			continue;
+		/* these channel types cannot be handled by this trigger */
+		if (chan->type == IIO_POSITIONRELATIVE ||
+		    chan->type == IIO_PRESSURE)
+			continue;
+
+		if (state) {
+			cor = at91_adc_readl(st, AT91_SAMA5D2_COR);
+
+			if (chan->differential)
+				cor |= (BIT(chan->channel) |
+					BIT(chan->channel2)) <<
+					AT91_SAMA5D2_COR_DIFF_OFFSET;
+			else
+				cor &= ~(BIT(chan->channel) <<
+				       AT91_SAMA5D2_COR_DIFF_OFFSET);
+
+			at91_adc_writel(st, AT91_SAMA5D2_COR, cor);
+		}
+
+		if (state) {
+			at91_adc_writel(st, AT91_SAMA5D2_CHER,
+					BIT(chan->channel));
+			/* enable irq only if not using DMA */
+			if (!st->dma_st.dma_chan) {
+				at91_adc_writel(st, AT91_SAMA5D2_IER,
+						BIT(chan->channel));
+			}
+		} else {
+			/* disable irq only if not using DMA */
+			if (!st->dma_st.dma_chan) {
+				at91_adc_writel(st, AT91_SAMA5D2_IDR,
+						BIT(chan->channel));
+			}
+			at91_adc_writel(st, AT91_SAMA5D2_CHDR,
+					BIT(chan->channel));
+		}
+	}
+
+	return 0;
+}
+
+static int at91_adc_reenable_trigger(struct iio_trigger *trig)
+{
+	struct iio_dev *indio = iio_trigger_get_drvdata(trig);
+	struct at91_adc_state *st = iio_priv(indio);
+
+	/* if we are using DMA, we must not reenable irq after each trigger */
+	if (st->dma_st.dma_chan)
+		return 0;
+
+	enable_irq(st->irq);
+
+	/* Needed to ACK the DRDY interruption */
+	at91_adc_readl(st, AT91_SAMA5D2_LCDR);
+	return 0;
+}
+
+static const struct iio_trigger_ops at91_adc_trigger_ops = {
+	.set_trigger_state = &at91_adc_configure_trigger,
+	.try_reenable = &at91_adc_reenable_trigger,
+	.validate_device = iio_trigger_validate_own_device,
+};
+
+static int at91_adc_dma_size_done(struct at91_adc_state *st)
+{
+	struct dma_tx_state state;
+	enum dma_status status;
+	int i, size;
+
+	status = dmaengine_tx_status(st->dma_st.dma_chan,
+				     st->dma_st.dma_chan->cookie,
+				     &state);
+	if (status != DMA_IN_PROGRESS)
+		return 0;
+
+	/* Transferred length is size in bytes from end of buffer */
+	i = st->dma_st.rx_buf_sz - state.residue;
+
+	/* Return available bytes */
+	if (i >= st->dma_st.buf_idx)
+		size = i - st->dma_st.buf_idx;
+	else
+		size = st->dma_st.rx_buf_sz + i - st->dma_st.buf_idx;
+	return size;
+}
+
+static void at91_dma_buffer_done(void *data)
+{
+	struct iio_dev *indio_dev = data;
+
+	iio_trigger_poll_chained(indio_dev->trig);
+}
+
+static int at91_adc_dma_start(struct iio_dev *indio_dev)
+{
+	struct at91_adc_state *st = iio_priv(indio_dev);
+	struct dma_async_tx_descriptor *desc;
+	dma_cookie_t cookie;
+	int ret;
+	u8 bit;
+
+	if (!st->dma_st.dma_chan)
+		return 0;
+
+	/* we start a new DMA, so set buffer index to start */
+	st->dma_st.buf_idx = 0;
+
+	/*
+	 * compute buffer size w.r.t. watermark and enabled channels.
+	 * scan_bytes is aligned so we need an exact size for DMA
+	 */
+	st->dma_st.rx_buf_sz = 0;
+
+	for_each_set_bit(bit, indio_dev->active_scan_mask,
+			 indio_dev->num_channels) {
+		struct iio_chan_spec const *chan =
+					 at91_adc_chan_get(indio_dev, bit);
+
+		if (!chan)
+			continue;
+
+		st->dma_st.rx_buf_sz += chan->scan_type.storagebits / 8;
+	}
+	st->dma_st.rx_buf_sz *= st->dma_st.watermark;
+
+	/* Prepare a DMA cyclic transaction */
+	desc = dmaengine_prep_dma_cyclic(st->dma_st.dma_chan,
+					 st->dma_st.rx_dma_buf,
+					 st->dma_st.rx_buf_sz,
+					 st->dma_st.rx_buf_sz / 2,
+					 DMA_DEV_TO_MEM, DMA_PREP_INTERRUPT);
+
+	if (!desc) {
+		dev_err(&indio_dev->dev, "cannot prepare DMA cyclic\n");
+		return -EBUSY;
+	}
+
+	desc->callback = at91_dma_buffer_done;
+	desc->callback_param = indio_dev;
+
+	cookie = dmaengine_submit(desc);
+	ret = dma_submit_error(cookie);
+	if (ret) {
+		dev_err(&indio_dev->dev, "cannot submit DMA cyclic\n");
+		dmaengine_terminate_async(st->dma_st.dma_chan);
+		return ret;
+	}
+
+	/* enable general overrun error signaling */
+	at91_adc_writel(st, AT91_SAMA5D2_IER, AT91_SAMA5D2_IER_GOVRE);
+	/* Issue pending DMA requests */
+	dma_async_issue_pending(st->dma_st.dma_chan);
+
+	/* consider current time as DMA start time for timestamps */
+	st->dma_st.dma_ts = iio_get_time_ns(indio_dev);
+
+	dev_dbg(&indio_dev->dev, "DMA cyclic started\n");
+
+	return 0;
+}
+
+static int at91_adc_buffer_postenable(struct iio_dev *indio_dev)
+{
+	int ret;
+	struct at91_adc_state *st = iio_priv(indio_dev);
+
+	/* check if we are enabling triggered buffer or the touchscreen */
+	if (bitmap_subset(indio_dev->active_scan_mask,
+			  &st->touch_st.channels_bitmask,
+			  AT91_SAMA5D2_MAX_CHAN_IDX + 1)) {
+		/* touchscreen enabling */
+		return at91_adc_configure_touch(st, true);
+	}
+	/* if we are not in triggered mode, we cannot enable the buffer. */
+	if (!(indio_dev->currentmode & INDIO_ALL_TRIGGERED_MODES))
+		return -EINVAL;
+
+	/* we continue with the triggered buffer */
+	ret = at91_adc_dma_start(indio_dev);
+	if (ret) {
+		dev_err(&indio_dev->dev, "buffer postenable failed\n");
+		return ret;
+	}
+
+	return iio_triggered_buffer_postenable(indio_dev);
+}
+
+static int at91_adc_buffer_predisable(struct iio_dev *indio_dev)
+{
+	struct at91_adc_state *st = iio_priv(indio_dev);
+	int ret;
+	u8 bit;
+
+	/* check if we are disabling triggered buffer or the touchscreen */
+	if (bitmap_subset(indio_dev->active_scan_mask,
+			  &st->touch_st.channels_bitmask,
+			  AT91_SAMA5D2_MAX_CHAN_IDX + 1)) {
+		/* touchscreen disable */
+		return at91_adc_configure_touch(st, false);
+	}
+	/* if we are not in triggered mode, nothing to do here */
+	if (!(indio_dev->currentmode & INDIO_ALL_TRIGGERED_MODES))
+		return -EINVAL;
+
+	/* continue with the triggered buffer */
+	ret = iio_triggered_buffer_predisable(indio_dev);
+	if (ret < 0)
+		dev_err(&indio_dev->dev, "buffer predisable failed\n");
+
+	if (!st->dma_st.dma_chan)
+		return ret;
+
+	/* if we are using DMA we must clear registers and end DMA */
+	dmaengine_terminate_sync(st->dma_st.dma_chan);
+
+	/*
+	 * For each enabled channel we must read the last converted value
+	 * to clear EOC status and not get a possible interrupt later.
+	 * This value is being read by DMA from LCDR anyway
+	 */
+	for_each_set_bit(bit, indio_dev->active_scan_mask,
+			 indio_dev->num_channels) {
+		struct iio_chan_spec const *chan =
+					at91_adc_chan_get(indio_dev, bit);
+
+		if (!chan)
+			continue;
+		/* these channel types are virtual, no need to do anything */
+		if (chan->type == IIO_POSITIONRELATIVE ||
+		    chan->type == IIO_PRESSURE)
+			continue;
+		if (st->dma_st.dma_chan)
+			at91_adc_readl(st, chan->address);
+	}
+
+	/* read overflow register to clear possible overflow status */
+	at91_adc_readl(st, AT91_SAMA5D2_OVER);
+	return ret;
+}
+
+static const struct iio_buffer_setup_ops at91_buffer_setup_ops = {
+	.postenable = &at91_adc_buffer_postenable,
+	.predisable = &at91_adc_buffer_predisable,
+};
+
+static struct iio_trigger *at91_adc_allocate_trigger(struct iio_dev *indio,
+						     char *trigger_name)
+{
+	struct iio_trigger *trig;
+	int ret;
+
+	trig = devm_iio_trigger_alloc(&indio->dev, "%s-dev%d-%s", indio->name,
+				      indio->id, trigger_name);
+	if (!trig)
+		return NULL;
+
+	trig->dev.parent = indio->dev.parent;
+	iio_trigger_set_drvdata(trig, indio);
+	trig->ops = &at91_adc_trigger_ops;
+
+	ret = devm_iio_trigger_register(&indio->dev, trig);
+	if (ret)
+		return ERR_PTR(ret);
+
+	return trig;
+}
+
+static int at91_adc_trigger_init(struct iio_dev *indio)
+{
+	struct at91_adc_state *st = iio_priv(indio);
+
+	st->trig = at91_adc_allocate_trigger(indio, st->selected_trig->name);
+	if (IS_ERR(st->trig)) {
+		dev_err(&indio->dev,
+			"could not allocate trigger\n");
+		return PTR_ERR(st->trig);
+	}
+
+	return 0;
+}
+
+static void at91_adc_trigger_handler_nodma(struct iio_dev *indio_dev,
+					   struct iio_poll_func *pf)
+{
+	struct at91_adc_state *st = iio_priv(indio_dev);
+	int i = 0;
+	int val;
+	u8 bit;
+
+	for_each_set_bit(bit, indio_dev->active_scan_mask,
+			 indio_dev->num_channels) {
+		struct iio_chan_spec const *chan =
+					at91_adc_chan_get(indio_dev, bit);
+
+		if (!chan)
+			continue;
+		/*
+		 * Our external trigger only supports the voltage channels.
+		 * In case someone requested a different type of channel
+		 * just put zeroes to buffer.
+		 * This should not happen because we check the scan mode
+		 * and scan mask when we enable the buffer, and we don't allow
+		 * the buffer to start with a mixed mask (voltage and something
+		 * else).
+		 * Thus, emit a warning.
+		 */
+		if (chan->type == IIO_VOLTAGE) {
+			val = at91_adc_readl(st, chan->address);
+			at91_adc_adjust_val_osr(st, &val);
+			st->buffer[i] = val;
+		} else {
+			st->buffer[i] = 0;
+			WARN(true, "This trigger cannot handle this type of channel");
+		}
+		i++;
+	}
+	iio_push_to_buffers_with_timestamp(indio_dev, st->buffer,
+					   pf->timestamp);
+}
+
+static void at91_adc_trigger_handler_dma(struct iio_dev *indio_dev)
+{
+	struct at91_adc_state *st = iio_priv(indio_dev);
+	int transferred_len = at91_adc_dma_size_done(st);
+	s64 ns = iio_get_time_ns(indio_dev);
+	s64 interval;
+	int sample_index = 0, sample_count, sample_size;
+
+	u32 status = at91_adc_readl(st, AT91_SAMA5D2_ISR);
+	/* if we reached this point, we cannot sample faster */
+	if (status & AT91_SAMA5D2_IER_GOVRE)
+		pr_info_ratelimited("%s: conversion overrun detected\n",
+				    indio_dev->name);
+
+	sample_size = div_s64(st->dma_st.rx_buf_sz, st->dma_st.watermark);
+
+	sample_count = div_s64(transferred_len, sample_size);
+
+	/*
+	 * interval between samples is total time since last transfer handling
+	 * divided by the number of samples (total size divided by sample size)
+	 */
+	interval = div_s64((ns - st->dma_st.dma_ts), sample_count);
+
+	while (transferred_len >= sample_size) {
+		/*
+		 * for all the values in the current sample,
+		 * adjust the values inside the buffer for oversampling
+		 */
+		at91_adc_adjust_val_osr_array(st,
+					&st->dma_st.rx_buf[st->dma_st.buf_idx],
+					sample_size);
+
+		iio_push_to_buffers_with_timestamp(indio_dev,
+				(st->dma_st.rx_buf + st->dma_st.buf_idx),
+				(st->dma_st.dma_ts + interval * sample_index));
+		/* adjust remaining length */
+		transferred_len -= sample_size;
+		/* adjust buffer index */
+		st->dma_st.buf_idx += sample_size;
+		/* in case of reaching end of buffer, reset index */
+		if (st->dma_st.buf_idx >= st->dma_st.rx_buf_sz)
+			st->dma_st.buf_idx = 0;
+		sample_index++;
+	}
+	/* adjust saved time for next transfer handling */
+	st->dma_st.dma_ts = iio_get_time_ns(indio_dev);
+}
+
+static irqreturn_t at91_adc_trigger_handler(int irq, void *p)
+{
+	struct iio_poll_func *pf = p;
+	struct iio_dev *indio_dev = pf->indio_dev;
+	struct at91_adc_state *st = iio_priv(indio_dev);
+
+	if (st->dma_st.dma_chan)
+		at91_adc_trigger_handler_dma(indio_dev);
+	else
+		at91_adc_trigger_handler_nodma(indio_dev, pf);
+
+	iio_trigger_notify_done(indio_dev->trig);
+
+	return IRQ_HANDLED;
+}
+
+static int at91_adc_buffer_init(struct iio_dev *indio)
+{
+	struct at91_adc_state *st = iio_priv(indio);
+
+	if (st->selected_trig->hw_trig) {
+		return devm_iio_triggered_buffer_setup(&indio->dev, indio,
+			&iio_pollfunc_store_time,
+			&at91_adc_trigger_handler, &at91_buffer_setup_ops);
+	}
+	/*
+	 * we need to prepare the buffer ops in case we will get
+	 * another buffer attached (like a callback buffer for the touchscreen)
+	 */
+	indio->setup_ops = &at91_buffer_setup_ops;
+
+	return 0;
+}
+
+static unsigned at91_adc_startup_time(unsigned startup_time_min,
+				      unsigned adc_clk_khz)
+{
+	static const unsigned int startup_lookup[] = {
+		  0,   8,  16,  24,
+		 64,  80,  96, 112,
+		512, 576, 640, 704,
+		768, 832, 896, 960
+		};
+	unsigned ticks_min, i;
+
+	/*
+	 * Since the adc frequency is checked before, there is no reason
+	 * to not meet the startup time constraint.
+	 */
+
+	ticks_min = startup_time_min * adc_clk_khz / 1000;
+	for (i = 0; i < ARRAY_SIZE(startup_lookup); i++)
+		if (startup_lookup[i] > ticks_min)
+			break;
+
+	return i;
+}
+
+static void at91_adc_setup_samp_freq(struct at91_adc_state *st, unsigned freq)
+{
+	struct iio_dev *indio_dev = iio_priv_to_dev(st);
+	unsigned f_per, prescal, startup, mr;
+
+	f_per = clk_get_rate(st->per_clk);
+	prescal = (f_per / (2 * freq)) - 1;
+
+	startup = at91_adc_startup_time(st->soc_info.startup_time,
+					freq / 1000);
+
+	mr = at91_adc_readl(st, AT91_SAMA5D2_MR);
+	mr &= ~(AT91_SAMA5D2_MR_STARTUP_MASK | AT91_SAMA5D2_MR_PRESCAL_MASK);
+	mr |= AT91_SAMA5D2_MR_STARTUP(startup);
+	mr |= AT91_SAMA5D2_MR_PRESCAL(prescal);
+	at91_adc_writel(st, AT91_SAMA5D2_MR, mr);
+
+	dev_dbg(&indio_dev->dev, "freq: %u, startup: %u, prescal: %u\n",
+		freq, startup, prescal);
+	st->current_sample_rate = freq;
+}
+
+static inline unsigned at91_adc_get_sample_freq(struct at91_adc_state *st)
+{
+	return st->current_sample_rate;
+}
+
+static void at91_adc_touch_data_handler(struct iio_dev *indio_dev)
+{
+	struct at91_adc_state *st = iio_priv(indio_dev);
+	u8 bit;
+	u16 val;
+	int i = 0;
+
+	for_each_set_bit(bit, indio_dev->active_scan_mask,
+			 AT91_SAMA5D2_MAX_CHAN_IDX + 1) {
+		struct iio_chan_spec const *chan =
+					 at91_adc_chan_get(indio_dev, bit);
+
+		if (chan->type == IIO_POSITIONRELATIVE)
+			at91_adc_read_position(st, chan->channel, &val);
+		else if (chan->type == IIO_PRESSURE)
+			at91_adc_read_pressure(st, chan->channel, &val);
+		else
+			continue;
+		st->buffer[i] = val;
+		i++;
+	}
+	/*
+	 * Schedule work to push to buffers.
+	 * This is intended to push to the callback buffer that another driver
+	 * registered. We are still in a handler from our IRQ. If we push
+	 * directly, it means the other driver has it's callback called
+	 * from our IRQ context. Which is something we better avoid.
+	 * Let's schedule it after our IRQ is completed.
+	 */
+	schedule_work(&st->touch_st.workq);
+}
+
+static void at91_adc_pen_detect_interrupt(struct at91_adc_state *st)
+{
+	at91_adc_writel(st, AT91_SAMA5D2_IDR, AT91_SAMA5D2_IER_PEN);
+	at91_adc_writel(st, AT91_SAMA5D2_IER, AT91_SAMA5D2_IER_NOPEN |
+			AT91_SAMA5D2_IER_XRDY | AT91_SAMA5D2_IER_YRDY |
+			AT91_SAMA5D2_IER_PRDY);
+	at91_adc_writel(st, AT91_SAMA5D2_TRGR,
+			AT91_SAMA5D2_TRGR_TRGMOD_PERIODIC |
+			AT91_SAMA5D2_TRGR_TRGPER(st->touch_st.sample_period_val));
+	st->touch_st.touching = true;
+}
+
+static void at91_adc_no_pen_detect_interrupt(struct at91_adc_state *st)
+{
+	struct iio_dev *indio_dev = iio_priv_to_dev(st);
+
+	at91_adc_writel(st, AT91_SAMA5D2_TRGR,
+			AT91_SAMA5D2_TRGR_TRGMOD_NO_TRIGGER);
+	at91_adc_writel(st, AT91_SAMA5D2_IDR, AT91_SAMA5D2_IER_NOPEN |
+			AT91_SAMA5D2_IER_XRDY | AT91_SAMA5D2_IER_YRDY |
+			AT91_SAMA5D2_IER_PRDY);
+	st->touch_st.touching = false;
+
+	at91_adc_touch_data_handler(indio_dev);
+
+	at91_adc_writel(st, AT91_SAMA5D2_IER, AT91_SAMA5D2_IER_PEN);
+}
+
+static void at91_adc_workq_handler(struct work_struct *workq)
+{
+	struct at91_adc_touch *touch_st = container_of(workq,
+					struct at91_adc_touch, workq);
+	struct at91_adc_state *st = container_of(touch_st,
+					struct at91_adc_state, touch_st);
+	struct iio_dev *indio_dev = iio_priv_to_dev(st);
+
+	iio_push_to_buffers(indio_dev, st->buffer);
+}
+
+static irqreturn_t at91_adc_interrupt(int irq, void *private)
+{
+	struct iio_dev *indio = private;
+	struct at91_adc_state *st = iio_priv(indio);
+	u32 status = at91_adc_readl(st, AT91_SAMA5D2_ISR);
+	u32 imr = at91_adc_readl(st, AT91_SAMA5D2_IMR);
+	u32 rdy_mask = AT91_SAMA5D2_IER_XRDY | AT91_SAMA5D2_IER_YRDY |
+			AT91_SAMA5D2_IER_PRDY;
+
+	if (!(status & imr))
+		return IRQ_NONE;
+	if (status & AT91_SAMA5D2_IER_PEN) {
+		/* pen detected IRQ */
+		at91_adc_pen_detect_interrupt(st);
+	} else if ((status & AT91_SAMA5D2_IER_NOPEN)) {
+		/* nopen detected IRQ */
+		at91_adc_no_pen_detect_interrupt(st);
+	} else if ((status & AT91_SAMA5D2_ISR_PENS) &&
+		   ((status & rdy_mask) == rdy_mask)) {
+		/* periodic trigger IRQ - during pen sense */
+		at91_adc_touch_data_handler(indio);
+	} else if (status & AT91_SAMA5D2_ISR_PENS) {
+		/*
+		 * touching, but the measurements are not ready yet.
+		 * read and ignore.
+		 */
+		status = at91_adc_readl(st, AT91_SAMA5D2_XPOSR);
+		status = at91_adc_readl(st, AT91_SAMA5D2_YPOSR);
+		status = at91_adc_readl(st, AT91_SAMA5D2_PRESSR);
+	} else if (iio_buffer_enabled(indio) && !st->dma_st.dma_chan) {
+		/* triggered buffer without DMA */
+		disable_irq_nosync(irq);
+		iio_trigger_poll(indio->trig);
+	} else if (iio_buffer_enabled(indio) && st->dma_st.dma_chan) {
+		/* triggered buffer with DMA - should not happen */
+		disable_irq_nosync(irq);
+		WARN(true, "Unexpected irq occurred\n");
+	} else if (!iio_buffer_enabled(indio)) {
+		/* software requested conversion */
+		st->conversion_value = at91_adc_readl(st, st->chan->address);
+		st->conversion_done = true;
+		wake_up_interruptible(&st->wq_data_available);
+	}
+	return IRQ_HANDLED;
+}
+
+static int at91_adc_read_info_raw(struct iio_dev *indio_dev,
+				  struct iio_chan_spec const *chan, int *val)
+{
+	struct at91_adc_state *st = iio_priv(indio_dev);
+	u32 cor = 0;
+	u16 tmp_val;
+	int ret;
+
+	/*
+	 * Keep in mind that we cannot use software trigger or touchscreen
+	 * if external trigger is enabled
+	 */
+	if (chan->type == IIO_POSITIONRELATIVE) {
+		ret = iio_device_claim_direct_mode(indio_dev);
+		if (ret)
+			return ret;
+		mutex_lock(&st->lock);
+
+		ret = at91_adc_read_position(st, chan->channel,
+					     &tmp_val);
+		*val = tmp_val;
+		mutex_unlock(&st->lock);
+		iio_device_release_direct_mode(indio_dev);
+
+		return at91_adc_adjust_val_osr(st, val);
+	}
+	if (chan->type == IIO_PRESSURE) {
+		ret = iio_device_claim_direct_mode(indio_dev);
+		if (ret)
+			return ret;
+		mutex_lock(&st->lock);
+
+		ret = at91_adc_read_pressure(st, chan->channel,
+					     &tmp_val);
+		*val = tmp_val;
+		mutex_unlock(&st->lock);
+		iio_device_release_direct_mode(indio_dev);
+
+		return at91_adc_adjust_val_osr(st, val);
+	}
+
+	/* in this case we have a voltage channel */
+
+	ret = iio_device_claim_direct_mode(indio_dev);
+	if (ret)
+		return ret;
+	mutex_lock(&st->lock);
+
+	st->chan = chan;
+
+	if (chan->differential)
+		cor = (BIT(chan->channel) | BIT(chan->channel2)) <<
+		      AT91_SAMA5D2_COR_DIFF_OFFSET;
+
+	at91_adc_writel(st, AT91_SAMA5D2_COR, cor);
+	at91_adc_writel(st, AT91_SAMA5D2_CHER, BIT(chan->channel));
+	at91_adc_writel(st, AT91_SAMA5D2_IER, BIT(chan->channel));
+	at91_adc_writel(st, AT91_SAMA5D2_CR, AT91_SAMA5D2_CR_START);
+
+	ret = wait_event_interruptible_timeout(st->wq_data_available,
+					       st->conversion_done,
+					       msecs_to_jiffies(1000));
+	if (ret == 0)
+		ret = -ETIMEDOUT;
+
+	if (ret > 0) {
+		*val = st->conversion_value;
+		ret = at91_adc_adjust_val_osr(st, val);
+		if (chan->scan_type.sign == 's')
+			*val = sign_extend32(*val,
+					     chan->scan_type.realbits - 1);
+		st->conversion_done = false;
+	}
+
+	at91_adc_writel(st, AT91_SAMA5D2_IDR, BIT(chan->channel));
+	at91_adc_writel(st, AT91_SAMA5D2_CHDR, BIT(chan->channel));
+
+	/* Needed to ACK the DRDY interruption */
+	at91_adc_readl(st, AT91_SAMA5D2_LCDR);
+
+	mutex_unlock(&st->lock);
+
+	iio_device_release_direct_mode(indio_dev);
+	return ret;
+}
+
+static int at91_adc_read_raw(struct iio_dev *indio_dev,
+			     struct iio_chan_spec const *chan,
+			     int *val, int *val2, long mask)
+{
+	struct at91_adc_state *st = iio_priv(indio_dev);
+
+	switch (mask) {
+	case IIO_CHAN_INFO_RAW:
+		return at91_adc_read_info_raw(indio_dev, chan, val);
+	case IIO_CHAN_INFO_SCALE:
+		*val = st->vref_uv / 1000;
+		if (chan->differential)
+			*val *= 2;
+		*val2 = chan->scan_type.realbits;
+		return IIO_VAL_FRACTIONAL_LOG2;
+
+	case IIO_CHAN_INFO_SAMP_FREQ:
+		*val = at91_adc_get_sample_freq(st);
+		return IIO_VAL_INT;
+
+	case IIO_CHAN_INFO_OVERSAMPLING_RATIO:
+		*val = st->oversampling_ratio;
+		return IIO_VAL_INT;
+
+	default:
+		return -EINVAL;
+	}
+}
+
+static int at91_adc_write_raw(struct iio_dev *indio_dev,
+			      struct iio_chan_spec const *chan,
+			      int val, int val2, long mask)
+{
+	struct at91_adc_state *st = iio_priv(indio_dev);
+
+	switch (mask) {
+	case IIO_CHAN_INFO_OVERSAMPLING_RATIO:
+		if ((val != AT91_OSR_1SAMPLES) && (val != AT91_OSR_4SAMPLES) &&
+		    (val != AT91_OSR_16SAMPLES))
+			return -EINVAL;
+		/* if no change, optimize out */
+		if (val == st->oversampling_ratio)
+			return 0;
+		st->oversampling_ratio = val;
+		/* update ratio */
+		at91_adc_config_emr(st);
+		return 0;
+	case IIO_CHAN_INFO_SAMP_FREQ:
+		if (val < st->soc_info.min_sample_rate ||
+		    val > st->soc_info.max_sample_rate)
+			return -EINVAL;
+
+		at91_adc_setup_samp_freq(st, val);
+		return 0;
+	default:
+		return -EINVAL;
+	};
+}
+
+static void at91_adc_dma_init(struct platform_device *pdev)
+{
+	struct iio_dev *indio_dev = platform_get_drvdata(pdev);
+	struct at91_adc_state *st = iio_priv(indio_dev);
+	struct dma_slave_config config = {0};
+	/*
+	 * We make the buffer double the size of the fifo,
+	 * such that DMA uses one half of the buffer (full fifo size)
+	 * and the software uses the other half to read/write.
+	 */
+	unsigned int pages = DIV_ROUND_UP(AT91_HWFIFO_MAX_SIZE *
+					  AT91_BUFFER_MAX_CONVERSION_BYTES * 2,
+					  PAGE_SIZE);
+
+	if (st->dma_st.dma_chan)
+		return;
+
+	st->dma_st.dma_chan = dma_request_slave_channel(&pdev->dev, "rx");
+
+	if (!st->dma_st.dma_chan)  {
+		dev_info(&pdev->dev, "can't get DMA channel\n");
+		goto dma_exit;
+	}
+
+	st->dma_st.rx_buf = dma_alloc_coherent(st->dma_st.dma_chan->device->dev,
+					       pages * PAGE_SIZE,
+					       &st->dma_st.rx_dma_buf,
+					       GFP_KERNEL);
+	if (!st->dma_st.rx_buf) {
+		dev_info(&pdev->dev, "can't allocate coherent DMA area\n");
+		goto dma_chan_disable;
+	}
+
+	/* Configure DMA channel to read data register */
+	config.direction = DMA_DEV_TO_MEM;
+	config.src_addr = (phys_addr_t)(st->dma_st.phys_addr
+			  + AT91_SAMA5D2_LCDR);
+	config.src_addr_width = DMA_SLAVE_BUSWIDTH_2_BYTES;
+	config.src_maxburst = 1;
+	config.dst_maxburst = 1;
+
+	if (dmaengine_slave_config(st->dma_st.dma_chan, &config)) {
+		dev_info(&pdev->dev, "can't configure DMA slave\n");
+		goto dma_free_area;
+	}
+
+	dev_info(&pdev->dev, "using %s for rx DMA transfers\n",
+		 dma_chan_name(st->dma_st.dma_chan));
+
+	return;
+
+dma_free_area:
+	dma_free_coherent(st->dma_st.dma_chan->device->dev, pages * PAGE_SIZE,
+			  st->dma_st.rx_buf, st->dma_st.rx_dma_buf);
+dma_chan_disable:
+	dma_release_channel(st->dma_st.dma_chan);
+	st->dma_st.dma_chan = 0;
+dma_exit:
+	dev_info(&pdev->dev, "continuing without DMA support\n");
+}
+
+static void at91_adc_dma_disable(struct platform_device *pdev)
+{
+	struct iio_dev *indio_dev = platform_get_drvdata(pdev);
+	struct at91_adc_state *st = iio_priv(indio_dev);
+	unsigned int pages = DIV_ROUND_UP(AT91_HWFIFO_MAX_SIZE *
+					  AT91_BUFFER_MAX_CONVERSION_BYTES * 2,
+					  PAGE_SIZE);
+
+	/* if we are not using DMA, just return */
+	if (!st->dma_st.dma_chan)
+		return;
+
+	/* wait for all transactions to be terminated first*/
+	dmaengine_terminate_sync(st->dma_st.dma_chan);
+
+	dma_free_coherent(st->dma_st.dma_chan->device->dev, pages * PAGE_SIZE,
+			  st->dma_st.rx_buf, st->dma_st.rx_dma_buf);
+	dma_release_channel(st->dma_st.dma_chan);
+	st->dma_st.dma_chan = 0;
+
+	dev_info(&pdev->dev, "continuing without DMA support\n");
+}
+
+static int at91_adc_set_watermark(struct iio_dev *indio_dev, unsigned int val)
+{
+	struct at91_adc_state *st = iio_priv(indio_dev);
+
+	if (val > AT91_HWFIFO_MAX_SIZE)
+		return -EINVAL;
+
+	if (!st->selected_trig->hw_trig) {
+		dev_dbg(&indio_dev->dev, "we need hw trigger for DMA\n");
+		return 0;
+	}
+
+	dev_dbg(&indio_dev->dev, "new watermark is %u\n", val);
+	st->dma_st.watermark = val;
+
+	/*
+	 * The logic here is: if we have watermark 1, it means we do
+	 * each conversion with it's own IRQ, thus we don't need DMA.
+	 * If the watermark is higher, we do DMA to do all the transfers in bulk
+	 */
+
+	if (val == 1)
+		at91_adc_dma_disable(to_platform_device(&indio_dev->dev));
+	else if (val > 1)
+		at91_adc_dma_init(to_platform_device(&indio_dev->dev));
+
+	return 0;
+}
+
+static int at91_adc_update_scan_mode(struct iio_dev *indio_dev,
+				     const unsigned long *scan_mask)
+{
+	struct at91_adc_state *st = iio_priv(indio_dev);
+
+	if (bitmap_subset(scan_mask, &st->touch_st.channels_bitmask,
+			  AT91_SAMA5D2_MAX_CHAN_IDX + 1))
+		return 0;
+	/*
+	 * if the new bitmap is a combination of touchscreen and regular
+	 * channels, then we are not fine
+	 */
+	if (bitmap_intersects(&st->touch_st.channels_bitmask, scan_mask,
+			      AT91_SAMA5D2_MAX_CHAN_IDX + 1))
+		return -EINVAL;
+	return 0;
+}
+
+static void at91_adc_hw_init(struct at91_adc_state *st)
+{
+	at91_adc_writel(st, AT91_SAMA5D2_CR, AT91_SAMA5D2_CR_SWRST);
+	at91_adc_writel(st, AT91_SAMA5D2_IDR, 0xffffffff);
+	/*
+	 * Transfer field must be set to 2 according to the datasheet and
+	 * allows different analog settings for each channel.
+	 */
+	at91_adc_writel(st, AT91_SAMA5D2_MR,
+			AT91_SAMA5D2_MR_TRANSFER(2) | AT91_SAMA5D2_MR_ANACH);
+
+	at91_adc_setup_samp_freq(st, st->soc_info.min_sample_rate);
+
+	/* configure extended mode register */
+	at91_adc_config_emr(st);
+}
+
+static ssize_t at91_adc_get_fifo_state(struct device *dev,
+				       struct device_attribute *attr, char *buf)
+{
+	struct iio_dev *indio_dev =
+			platform_get_drvdata(to_platform_device(dev));
+	struct at91_adc_state *st = iio_priv(indio_dev);
+
+	return scnprintf(buf, PAGE_SIZE, "%d\n", !!st->dma_st.dma_chan);
+}
+
+static ssize_t at91_adc_get_watermark(struct device *dev,
+				      struct device_attribute *attr, char *buf)
+{
+	struct iio_dev *indio_dev =
+			platform_get_drvdata(to_platform_device(dev));
+	struct at91_adc_state *st = iio_priv(indio_dev);
+
+	return scnprintf(buf, PAGE_SIZE, "%d\n", st->dma_st.watermark);
+}
+
+static IIO_DEVICE_ATTR(hwfifo_enabled, 0444,
+		       at91_adc_get_fifo_state, NULL, 0);
+static IIO_DEVICE_ATTR(hwfifo_watermark, 0444,
+		       at91_adc_get_watermark, NULL, 0);
+
+static IIO_CONST_ATTR(hwfifo_watermark_min, "2");
+static IIO_CONST_ATTR(hwfifo_watermark_max, AT91_HWFIFO_MAX_SIZE_STR);
+
+static IIO_CONST_ATTR(oversampling_ratio_available,
+		      __stringify(AT91_OSR_1SAMPLES) " "
+		      __stringify(AT91_OSR_4SAMPLES) " "
+		      __stringify(AT91_OSR_16SAMPLES));
+
+static struct attribute *at91_adc_attributes[] = {
+	&iio_const_attr_oversampling_ratio_available.dev_attr.attr,
+	NULL,
+};
+
+static const struct attribute_group at91_adc_attribute_group = {
+	.attrs = at91_adc_attributes,
+};
+
+static const struct attribute *at91_adc_fifo_attributes[] = {
+	&iio_const_attr_hwfifo_watermark_min.dev_attr.attr,
+	&iio_const_attr_hwfifo_watermark_max.dev_attr.attr,
+	&iio_dev_attr_hwfifo_watermark.dev_attr.attr,
+	&iio_dev_attr_hwfifo_enabled.dev_attr.attr,
+	NULL,
+};
+
+static const struct iio_info at91_adc_info = {
+	.attrs = &at91_adc_attribute_group,
+	.read_raw = &at91_adc_read_raw,
+	.write_raw = &at91_adc_write_raw,
+	.update_scan_mode = &at91_adc_update_scan_mode,
+	.of_xlate = &at91_adc_of_xlate,
+	.hwfifo_set_watermark = &at91_adc_set_watermark,
+};
+
+static int at91_adc_probe(struct platform_device *pdev)
+{
+	struct iio_dev *indio_dev;
+	struct at91_adc_state *st;
+	struct resource	*res;
+	int ret, i;
+	u32 edge_type = IRQ_TYPE_NONE;
+
+	indio_dev = devm_iio_device_alloc(&pdev->dev, sizeof(*st));
+	if (!indio_dev)
+		return -ENOMEM;
+
+	indio_dev->dev.parent = &pdev->dev;
+	indio_dev->name = dev_name(&pdev->dev);
+	indio_dev->modes = INDIO_DIRECT_MODE | INDIO_BUFFER_SOFTWARE;
+	indio_dev->info = &at91_adc_info;
+	indio_dev->channels = at91_adc_channels;
+	indio_dev->num_channels = ARRAY_SIZE(at91_adc_channels);
+
+	st = iio_priv(indio_dev);
+
+	bitmap_set(&st->touch_st.channels_bitmask,
+		   AT91_SAMA5D2_TOUCH_X_CHAN_IDX, 1);
+	bitmap_set(&st->touch_st.channels_bitmask,
+		   AT91_SAMA5D2_TOUCH_Y_CHAN_IDX, 1);
+	bitmap_set(&st->touch_st.channels_bitmask,
+		   AT91_SAMA5D2_TOUCH_P_CHAN_IDX, 1);
+
+	st->oversampling_ratio = AT91_OSR_1SAMPLES;
+
+	ret = of_property_read_u32(pdev->dev.of_node,
+				   "atmel,min-sample-rate-hz",
+				   &st->soc_info.min_sample_rate);
+	if (ret) {
+		dev_err(&pdev->dev,
+			"invalid or missing value for atmel,min-sample-rate-hz\n");
+		return ret;
+	}
+
+	ret = of_property_read_u32(pdev->dev.of_node,
+				   "atmel,max-sample-rate-hz",
+				   &st->soc_info.max_sample_rate);
+	if (ret) {
+		dev_err(&pdev->dev,
+			"invalid or missing value for atmel,max-sample-rate-hz\n");
+		return ret;
+	}
+
+	ret = of_property_read_u32(pdev->dev.of_node, "atmel,startup-time-ms",
+				   &st->soc_info.startup_time);
+	if (ret) {
+		dev_err(&pdev->dev,
+			"invalid or missing value for atmel,startup-time-ms\n");
+		return ret;
+	}
+
+	ret = of_property_read_u32(pdev->dev.of_node,
+				   "atmel,trigger-edge-type", &edge_type);
+	if (ret) {
+		dev_dbg(&pdev->dev,
+			"atmel,trigger-edge-type not specified, only software trigger available\n");
+	}
+
+	st->selected_trig = NULL;
+
+	/* find the right trigger, or no trigger at all */
+	for (i = 0; i < AT91_SAMA5D2_HW_TRIG_CNT + 1; i++)
+		if (at91_adc_trigger_list[i].edge_type == edge_type) {
+			st->selected_trig = &at91_adc_trigger_list[i];
+			break;
+		}
+
+	if (!st->selected_trig) {
+		dev_err(&pdev->dev, "invalid external trigger edge value\n");
+		return -EINVAL;
+	}
+
+	init_waitqueue_head(&st->wq_data_available);
+	mutex_init(&st->lock);
+	INIT_WORK(&st->touch_st.workq, at91_adc_workq_handler);
+
+	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+	if (!res)
+		return -EINVAL;
+
+	/* if we plan to use DMA, we need the physical address of the regs */
+	st->dma_st.phys_addr = res->start;
+
+	st->base = devm_ioremap_resource(&pdev->dev, res);
+	if (IS_ERR(st->base))
+		return PTR_ERR(st->base);
+
+	st->irq = platform_get_irq(pdev, 0);
+	if (st->irq <= 0) {
+		if (!st->irq)
+			st->irq = -ENXIO;
+
+		return st->irq;
+	}
+
+	st->per_clk = devm_clk_get(&pdev->dev, "adc_clk");
+	if (IS_ERR(st->per_clk))
+		return PTR_ERR(st->per_clk);
+
+	st->reg = devm_regulator_get(&pdev->dev, "vddana");
+	if (IS_ERR(st->reg))
+		return PTR_ERR(st->reg);
+
+	st->vref = devm_regulator_get(&pdev->dev, "vref");
+	if (IS_ERR(st->vref))
+		return PTR_ERR(st->vref);
+
+	ret = devm_request_irq(&pdev->dev, st->irq, at91_adc_interrupt, 0,
+			       pdev->dev.driver->name, indio_dev);
+	if (ret)
+		return ret;
+
+	ret = regulator_enable(st->reg);
+	if (ret)
+		return ret;
+
+	ret = regulator_enable(st->vref);
+	if (ret)
+		goto reg_disable;
+
+	st->vref_uv = regulator_get_voltage(st->vref);
+	if (st->vref_uv <= 0) {
+		ret = -EINVAL;
+		goto vref_disable;
+	}
+
+	at91_adc_hw_init(st);
+
+	ret = clk_prepare_enable(st->per_clk);
+	if (ret)
+		goto vref_disable;
+
+	platform_set_drvdata(pdev, indio_dev);
+
+	ret = at91_adc_buffer_init(indio_dev);
+	if (ret < 0) {
+		dev_err(&pdev->dev, "couldn't initialize the buffer.\n");
+		goto per_clk_disable_unprepare;
+	}
+
+	if (st->selected_trig->hw_trig) {
+		ret = at91_adc_trigger_init(indio_dev);
+		if (ret < 0) {
+			dev_err(&pdev->dev, "couldn't setup the triggers.\n");
+			goto per_clk_disable_unprepare;
+		}
+		/*
+		 * Initially the iio buffer has a length of 2 and
+		 * a watermark of 1
+		 */
+		st->dma_st.watermark = 1;
+
+		iio_buffer_set_attrs(indio_dev->buffer,
+				     at91_adc_fifo_attributes);
+	}
+
+	if (dma_coerce_mask_and_coherent(&indio_dev->dev, DMA_BIT_MASK(32)))
+		dev_info(&pdev->dev, "cannot set DMA mask to 32-bit\n");
+
+	ret = iio_device_register(indio_dev);
+	if (ret < 0)
+		goto dma_disable;
+
+	if (st->selected_trig->hw_trig)
+		dev_info(&pdev->dev, "setting up trigger as %s\n",
+			 st->selected_trig->name);
+
+	dev_info(&pdev->dev, "version: %x\n",
+		 readl_relaxed(st->base + AT91_SAMA5D2_VERSION));
+
+	return 0;
+
+dma_disable:
+	at91_adc_dma_disable(pdev);
+per_clk_disable_unprepare:
+	clk_disable_unprepare(st->per_clk);
+vref_disable:
+	regulator_disable(st->vref);
+reg_disable:
+	regulator_disable(st->reg);
+	return ret;
+}
+
+static int at91_adc_remove(struct platform_device *pdev)
+{
+	struct iio_dev *indio_dev = platform_get_drvdata(pdev);
+	struct at91_adc_state *st = iio_priv(indio_dev);
+
+	iio_device_unregister(indio_dev);
+
+	at91_adc_dma_disable(pdev);
+
+	clk_disable_unprepare(st->per_clk);
+
+	regulator_disable(st->vref);
+	regulator_disable(st->reg);
+
+	return 0;
+}
+
+static __maybe_unused int at91_adc_suspend(struct device *dev)
+{
+	struct iio_dev *indio_dev =
+			platform_get_drvdata(to_platform_device(dev));
+	struct at91_adc_state *st = iio_priv(indio_dev);
+
+	/*
+	 * Do a sofware reset of the ADC before we go to suspend.
+	 * this will ensure that all pins are free from being muxed by the ADC
+	 * and can be used by for other devices.
+	 * Otherwise, ADC will hog them and we can't go to suspend mode.
+	 */
+	at91_adc_writel(st, AT91_SAMA5D2_CR, AT91_SAMA5D2_CR_SWRST);
+
+	clk_disable_unprepare(st->per_clk);
+	regulator_disable(st->vref);
+	regulator_disable(st->reg);
+
+	return pinctrl_pm_select_sleep_state(dev);
+}
+
+static __maybe_unused int at91_adc_resume(struct device *dev)
+{
+	struct iio_dev *indio_dev =
+			platform_get_drvdata(to_platform_device(dev));
+	struct at91_adc_state *st = iio_priv(indio_dev);
+	int ret;
+
+	ret = pinctrl_pm_select_default_state(dev);
+	if (ret)
+		goto resume_failed;
+
+	ret = regulator_enable(st->reg);
+	if (ret)
+		goto resume_failed;
+
+	ret = regulator_enable(st->vref);
+	if (ret)
+		goto reg_disable_resume;
+
+	ret = clk_prepare_enable(st->per_clk);
+	if (ret)
+		goto vref_disable_resume;
+
+	at91_adc_hw_init(st);
+
+	/* reconfiguring trigger hardware state */
+	if (!iio_buffer_enabled(indio_dev))
+		return 0;
+
+	/* check if we are enabling triggered buffer or the touchscreen */
+	if (bitmap_subset(indio_dev->active_scan_mask,
+			  &st->touch_st.channels_bitmask,
+			  AT91_SAMA5D2_MAX_CHAN_IDX + 1)) {
+		/* touchscreen enabling */
+		return at91_adc_configure_touch(st, true);
+	} else {
+		return at91_adc_configure_trigger(st->trig, true);
+	}
+
+	/* not needed but more explicit */
+	return 0;
+
+vref_disable_resume:
+	regulator_disable(st->vref);
+reg_disable_resume:
+	regulator_disable(st->reg);
+resume_failed:
+	dev_err(&indio_dev->dev, "failed to resume\n");
+	return ret;
+}
+
+static SIMPLE_DEV_PM_OPS(at91_adc_pm_ops, at91_adc_suspend, at91_adc_resume);
+
+static const struct of_device_id at91_adc_dt_match[] = {
+	{
+		.compatible = "atmel,sama5d2-adc",
+	}, {
+		/* sentinel */
+	}
+};
+MODULE_DEVICE_TABLE(of, at91_adc_dt_match);
+
+static struct platform_driver at91_adc_driver = {
+	.probe = at91_adc_probe,
+	.remove = at91_adc_remove,
+	.driver = {
+		.name = "at91-sama5d2_adc",
+		.of_match_table = at91_adc_dt_match,
+		.pm = &at91_adc_pm_ops,
+	},
+};
+module_platform_driver(at91_adc_driver)
+
+MODULE_AUTHOR("Ludovic Desroches <ludovic.desroches@atmel.com>");
+MODULE_DESCRIPTION("Atmel AT91 SAMA5D2 ADC");
+MODULE_LICENSE("GPL v2");