Merge tag 'staging-4.16-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/staging

Pull staging/IIO updates from Greg KH:
 "Here is the big Staging and IIO driver patches for 4.16-rc1.

  There is the normal amount of new IIO drivers added, like all
  releases.

  The networking IPX and the ncpfs filesystem are moved into the staging
  tree, as they are on their way out of the kernel due to lack of use
  anymore.

  The visorbus subsystem finall has started moving out of the staging
  tree to the "real" part of the kernel, and the most and fsl-mc
  codebases are almost ready to move out, that will probably happen for
  4.17-rc1 if all goes well.

  Other than that, there is a bunch of license header cleanups in the
  tree, along with the normal amount of coding style churn that we all
  know and love for this codebase. I also got frustrated at the
  Meltdown/Spectre mess and took it out on the dgnc tty driver, deleting
  huge chunks of it that were never even being used.

  Full details of everything is in the shortlog.

  All of these patches have been in linux-next for a while with no
  reported issues"

* tag 'staging-4.16-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/staging: (627 commits)
  staging: rtlwifi: remove redundant initialization of 'cfg_cmd'
  staging: rtl8723bs: remove a couple of redundant initializations
  staging: comedi: reformat lines to 80 chars or less
  staging: lustre: separate a connection destroy from free struct kib_conn
  Staging: rtl8723bs: Use !x instead of NULL comparison
  Staging: rtl8723bs: Remove dead code
  Staging: rtl8723bs: Change names to conform to the kernel code
  staging: ccree: Fix missing blank line after declaration
  staging: rtl8188eu: remove redundant initialization of 'pwrcfgcmd'
  staging: rtlwifi: remove unused RTLHALMAC_ST and RTLPHYDM_ST
  staging: fbtft: remove unused FB_TFT_SSD1325 kconfig
  staging: comedi: dt2811: remove redundant initialization of 'ns'
  staging: wilc1000: fix alignments to match open parenthesis
  staging: wilc1000: removed unnecessary defined enums typedef
  staging: wilc1000: remove unnecessary use of parentheses
  staging: rtl8192u: remove redundant initialization of 'timeout'
  staging: sm750fb: fix CamelCase for dispSet var
  staging: lustre: lnet/selftest: fix compile error on UP build
  staging: rtl8723bs: hal_com_phycfg: Remove unneeded semicolons
  staging: rts5208: Fix "seg_no" calculation in reset_ms_card()
  ...

59 files changed, 2756 insertions, 808 deletions

diff --git a/drivers/iio/accel/bmc150-accel-i2c.c b/drivers/iio/accel/bmc150-accel-i2c.c
index f85014fbaa12..8ffc308d5fd0 100644
--- a/drivers/iio/accel/bmc150-accel-i2c.c
+++ b/drivers/iio/accel/bmc150-accel-i2c.c
@@ -81,9 +81,21 @@ static const struct i2c_device_id bmc150_accel_id[] = {
 
 MODULE_DEVICE_TABLE(i2c, bmc150_accel_id);
 
+static const struct of_device_id bmc150_accel_of_match[] = {
+	{ .compatible = "bosch,bmc150_accel" },
+	{ .compatible = "bosch,bmi055_accel" },
+	{ .compatible = "bosch,bma255" },
+	{ .compatible = "bosch,bma250e" },
+	{ .compatible = "bosch,bma222e" },
+	{ .compatible = "bosch,bma280" },
+	{ },
+};
+MODULE_DEVICE_TABLE(of, bmc150_accel_of_match);
+
 static struct i2c_driver bmc150_accel_driver = {
 	.driver = {
 		.name	= "bmc150_accel_i2c",
+		.of_match_table = bmc150_accel_of_match,
 		.acpi_match_table = ACPI_PTR(bmc150_accel_acpi_match),
 		.pm	= &bmc150_accel_pm_ops,
 	},
diff --git a/drivers/iio/accel/da280.c b/drivers/iio/accel/da280.c
index 6c214783241c..d4b555203427 100644
--- a/drivers/iio/accel/da280.c
+++ b/drivers/iio/accel/da280.c
@@ -11,6 +11,7 @@
 
 #include <linux/module.h>
 #include <linux/i2c.h>
+#include <linux/acpi.h>
 #include <linux/iio/iio.h>
 #include <linux/iio/sysfs.h>
 #include <linux/byteorder/generic.h>
@@ -25,7 +26,7 @@
 #define DA280_MODE_ENABLE		0x1e
 #define DA280_MODE_DISABLE		0x9e
 
-enum { da226, da280 };
+enum da280_chipset { da226, da280 };
 
 /*
  * a value of + or -4096 corresponds to + or - 1G
@@ -91,12 +92,24 @@ static const struct iio_info da280_info = {
 	.read_raw	= da280_read_raw,
 };
 
+static enum da280_chipset da280_match_acpi_device(struct device *dev)
+{
+	const struct acpi_device_id *id;
+
+	id = acpi_match_device(dev->driver->acpi_match_table, dev);
+	if (!id)
+		return -EINVAL;
+
+	return (enum da280_chipset) id->driver_data;
+}
+
 static int da280_probe(struct i2c_client *client,
 			const struct i2c_device_id *id)
 {
 	int ret;
 	struct iio_dev *indio_dev;
 	struct da280_data *data;
+	enum da280_chipset chip;
 
 	ret = i2c_smbus_read_byte_data(client, DA280_REG_CHIP_ID);
 	if (ret != DA280_CHIP_ID)
@@ -114,7 +127,14 @@ static int da280_probe(struct i2c_client *client,
 	indio_dev->info = &da280_info;
 	indio_dev->modes = INDIO_DIRECT_MODE;
 	indio_dev->channels = da280_channels;
-	if (id->driver_data == da226) {
+
+	if (ACPI_HANDLE(&client->dev)) {
+		chip = da280_match_acpi_device(&client->dev);
+	} else {
+		chip = id->driver_data;
+	}
+
+	if (chip == da226) {
 		indio_dev->name = "da226";
 		indio_dev->num_channels = 2;
 	} else {
@@ -158,6 +178,12 @@ static int da280_resume(struct device *dev)
 
 static SIMPLE_DEV_PM_OPS(da280_pm_ops, da280_suspend, da280_resume);
 
+static const struct acpi_device_id da280_acpi_match[] = {
+	{"MIRAACC", da280},
+	{},
+};
+MODULE_DEVICE_TABLE(acpi, da280_acpi_match);
+
 static const struct i2c_device_id da280_i2c_id[] = {
 	{ "da226", da226 },
 	{ "da280", da280 },
@@ -168,6 +194,7 @@ MODULE_DEVICE_TABLE(i2c, da280_i2c_id);
 static struct i2c_driver da280_driver = {
 	.driver = {
 		.name = "da280",
+		.acpi_match_table = ACPI_PTR(da280_acpi_match),
 		.pm = &da280_pm_ops,
 	},
 	.probe		= da280_probe,
diff --git a/drivers/iio/accel/kxsd9-i2c.c b/drivers/iio/accel/kxsd9-i2c.c
index 98fbb628d5bd..38411e1c155b 100644
--- a/drivers/iio/accel/kxsd9-i2c.c
+++ b/drivers/iio/accel/kxsd9-i2c.c
@@ -63,3 +63,6 @@ static struct i2c_driver kxsd9_i2c_driver = {
 	.id_table	= kxsd9_i2c_id,
 };
 module_i2c_driver(kxsd9_i2c_driver);
+
+MODULE_LICENSE("GPL v2");
+MODULE_DESCRIPTION("KXSD9 accelerometer I2C interface");
diff --git a/drivers/iio/accel/mma8452.c b/drivers/iio/accel/mma8452.c
index bfd4bc806fc2..7a2da7f9d4dc 100644
--- a/drivers/iio/accel/mma8452.c
+++ b/drivers/iio/accel/mma8452.c
@@ -1,3 +1,4 @@
+// SPDX-License-Identifier: GPL-2.0
 /*
  * mma8452.c - Support for following Freescale / NXP 3-axis accelerometers:
  *
@@ -13,9 +14,6 @@
  * Copyright 2015 Martin Kepplinger <martink@posteo.de>
  * Copyright 2014 Peter Meerwald <pmeerw@pmeerw.net>
  *
- * This file is subject to the terms and conditions of version 2 of
- * the GNU General Public License.  See the file COPYING in the main
- * directory of this archive for more details.
  *
  * TODO: orientation events
  */
@@ -135,7 +133,7 @@ struct mma8452_event_regs {
 		u8 ev_count;
 };
 
-static const struct mma8452_event_regs ev_regs_accel_falling = {
+static const struct mma8452_event_regs ff_mt_ev_regs = {
 		.ev_cfg = MMA8452_FF_MT_CFG,
 		.ev_cfg_ele = MMA8452_FF_MT_CFG_ELE,
 		.ev_cfg_chan_shift = MMA8452_FF_MT_CHAN_SHIFT,
@@ -145,7 +143,7 @@ static const struct mma8452_event_regs ev_regs_accel_falling = {
 		.ev_count = MMA8452_FF_MT_COUNT
 };
 
-static const struct mma8452_event_regs ev_regs_accel_rising = {
+static const struct mma8452_event_regs trans_ev_regs = {
 		.ev_cfg = MMA8452_TRANSIENT_CFG,
 		.ev_cfg_ele = MMA8452_TRANSIENT_CFG_ELE,
 		.ev_cfg_chan_shift = MMA8452_TRANSIENT_CHAN_SHIFT,
@@ -284,7 +282,7 @@ static const int mma8452_samp_freq[8][2] = {
 };
 
 /* Datasheet table: step time "Relationship with the ODR" (sample frequency) */
-static const unsigned int mma8452_transient_time_step_us[4][8] = {
+static const unsigned int mma8452_time_step_us[4][8] = {
 	{ 1250, 2500, 5000, 10000, 20000, 20000, 20000, 20000 },  /* normal */
 	{ 1250, 2500, 5000, 10000, 20000, 80000, 80000, 80000 },  /* l p l n */
 	{ 1250, 2500, 2500, 2500, 2500, 2500, 2500, 2500 },	  /* high res*/
@@ -777,12 +775,12 @@ static int mma8452_get_event_regs(struct mma8452_data *data,
 					& MMA8452_INT_TRANS) &&
 				(data->chip_info->enabled_events
 					& MMA8452_INT_TRANS))
-				*ev_reg = &ev_regs_accel_rising;
+				*ev_reg = &trans_ev_regs;
 			else
-				*ev_reg = &ev_regs_accel_falling;
+				*ev_reg = &ff_mt_ev_regs;
 			return 0;
 		case IIO_EV_DIR_FALLING:
-			*ev_reg = &ev_regs_accel_falling;
+			*ev_reg = &ff_mt_ev_regs;
 			return 0;
 		default:
 			return -EINVAL;
@@ -826,7 +824,7 @@ static int mma8452_read_event_value(struct iio_dev *indio_dev,
 		if (power_mode < 0)
 			return power_mode;
 
-		us = ret * mma8452_transient_time_step_us[power_mode][
+		us = ret * mma8452_time_step_us[power_mode][
 				mma8452_get_odr_index(data)];
 		*val = us / USEC_PER_SEC;
 		*val2 = us % USEC_PER_SEC;
@@ -883,7 +881,7 @@ static int mma8452_write_event_value(struct iio_dev *indio_dev,
 			return ret;
 
 		steps = (val * USEC_PER_SEC + val2) /
-				mma8452_transient_time_step_us[ret][
+				mma8452_time_step_us[ret][
 					mma8452_get_odr_index(data)];
 
 		if (steps < 0 || steps > 0xff)
diff --git a/drivers/iio/accel/st_accel_core.c b/drivers/iio/accel/st_accel_core.c
index 460aa58e0159..6fe995cf16a6 100644
--- a/drivers/iio/accel/st_accel_core.c
+++ b/drivers/iio/accel/st_accel_core.c
@@ -920,8 +920,6 @@ static const struct iio_trigger_ops st_accel_trigger_ops = {
 int st_accel_common_probe(struct iio_dev *indio_dev)
 {
 	struct st_sensor_data *adata = iio_priv(indio_dev);
-	struct st_sensors_platform_data *pdata =
-		(struct st_sensors_platform_data *)adata->dev->platform_data;
 	int irq = adata->get_irq_data_ready(indio_dev);
 	int err;
 
@@ -948,9 +946,6 @@ int st_accel_common_probe(struct iio_dev *indio_dev)
 					&adata->sensor_settings->fs.fs_avl[0];
 	adata->odr = adata->sensor_settings->odr.odr_avl[0].hz;
 
-	if (!pdata)
-		pdata = (struct st_sensors_platform_data *)&default_accel_pdata;
-
 	err = st_sensors_init_sensor(indio_dev, adata->dev->platform_data);
 	if (err < 0)
 		goto st_accel_power_off;
diff --git a/drivers/iio/adc/Kconfig b/drivers/iio/adc/Kconfig
index 39e3b345a6c8..72bc2b71765a 100644
--- a/drivers/iio/adc/Kconfig
+++ b/drivers/iio/adc/Kconfig
@@ -158,6 +158,7 @@ config AT91_SAMA5D2_ADC
 	tristate "Atmel AT91 SAMA5D2 ADC"
 	depends on ARCH_AT91 || COMPILE_TEST
 	depends on HAS_IOMEM
+	depends on HAS_DMA
 	select IIO_TRIGGERED_BUFFER
 	help
 	  Say yes here to build support for Atmel SAMA5D2 ADC which is
@@ -318,6 +319,8 @@ config HI8435
 config HX711
 	tristate "AVIA HX711 ADC for weight cells"
 	depends on GPIOLIB
+	select IIO_BUFFER
+	select IIO_TRIGGERED_BUFFER
 	help
 	  If you say yes here you get support for AVIA HX711 ADC which is used
 	  for weigh cells
diff --git a/drivers/iio/adc/aspeed_adc.c b/drivers/iio/adc/aspeed_adc.c
index 8a958d5f1905..327a49ba1991 100644
--- a/drivers/iio/adc/aspeed_adc.c
+++ b/drivers/iio/adc/aspeed_adc.c
@@ -17,6 +17,7 @@
 #include <linux/module.h>
 #include <linux/of_platform.h>
 #include <linux/platform_device.h>
+#include <linux/reset.h>
 #include <linux/spinlock.h>
 #include <linux/types.h>
 
@@ -53,11 +54,12 @@ struct aspeed_adc_model_data {
 };
 
 struct aspeed_adc_data {
-	struct device	*dev;
-	void __iomem	*base;
-	spinlock_t	clk_lock;
-	struct clk_hw	*clk_prescaler;
-	struct clk_hw	*clk_scaler;
+	struct device		*dev;
+	void __iomem		*base;
+	spinlock_t		clk_lock;
+	struct clk_hw		*clk_prescaler;
+	struct clk_hw		*clk_scaler;
+	struct reset_control	*rst;
 };
 
 #define ASPEED_CHAN(_idx, _data_reg_addr) {			\
@@ -217,6 +219,15 @@ static int aspeed_adc_probe(struct platform_device *pdev)
 		goto scaler_error;
 	}
 
+	data->rst = devm_reset_control_get_exclusive(&pdev->dev, NULL);
+	if (IS_ERR(data->rst)) {
+		dev_err(&pdev->dev,
+			"invalid or missing reset controller device tree entry");
+		ret = PTR_ERR(data->rst);
+		goto reset_error;
+	}
+	reset_control_deassert(data->rst);
+
 	model_data = of_device_get_match_data(&pdev->dev);
 
 	if (model_data->wait_init_sequence) {
@@ -263,9 +274,10 @@ iio_register_error:
 	writel(ASPEED_OPERATION_MODE_POWER_DOWN,
 		data->base + ASPEED_REG_ENGINE_CONTROL);
 	clk_disable_unprepare(data->clk_scaler->clk);
+reset_error:
+	reset_control_assert(data->rst);
 clk_enable_error:
 	clk_hw_unregister_divider(data->clk_scaler);
-
 scaler_error:
 	clk_hw_unregister_divider(data->clk_prescaler);
 	return ret;
@@ -280,6 +292,7 @@ static int aspeed_adc_remove(struct platform_device *pdev)
 	writel(ASPEED_OPERATION_MODE_POWER_DOWN,
 		data->base + ASPEED_REG_ENGINE_CONTROL);
 	clk_disable_unprepare(data->clk_scaler->clk);
+	reset_control_assert(data->rst);
 	clk_hw_unregister_divider(data->clk_scaler);
 	clk_hw_unregister_divider(data->clk_prescaler);
 
diff --git a/drivers/iio/adc/at91-sama5d2_adc.c b/drivers/iio/adc/at91-sama5d2_adc.c
index 755a493c2a2c..4eff8351ce29 100644
--- a/drivers/iio/adc/at91-sama5d2_adc.c
+++ b/drivers/iio/adc/at91-sama5d2_adc.c
@@ -16,6 +16,8 @@
 
 #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>
@@ -100,6 +102,8 @@
 #define AT91_SAMA5D2_LCDR	0x20
 /* Interrupt Enable Register */
 #define AT91_SAMA5D2_IER	0x24
+/* Interrupt Enable Register - general overrun error */
+#define AT91_SAMA5D2_IER_GOVRE BIT(25)
 /* Interrupt Disable Register */
 #define AT91_SAMA5D2_IDR	0x28
 /* Interrupt Mask Register */
@@ -167,13 +171,19 @@
 
 /*
  * Maximum number of bytes to hold conversion from all channels
- * plus the timestamp
+ * without the timestamp.
  */
-#define AT91_BUFFER_MAX_BYTES ((AT91_SAMA5D2_SINGLE_CHAN_CNT +		\
-				AT91_SAMA5D2_DIFF_CHAN_CNT) * 2 + 8)
+#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
+
 #define AT91_SAMA5D2_CHAN_SINGLE(num, addr)				\
 	{								\
 		.type = IIO_VOLTAGE,					\
@@ -228,6 +238,28 @@ struct at91_adc_trigger {
 	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;
+};
+
 struct at91_adc_state {
 	void __iomem			*base;
 	int				irq;
@@ -242,6 +274,7 @@ struct at91_adc_state {
 	u32				conversion_value;
 	struct at91_adc_soc_info	soc_info;
 	wait_queue_head_t		wq_data_available;
+	struct at91_adc_dma		dma_st;
 	u16				buffer[AT91_BUFFER_MAX_HWORDS];
 	/*
 	 * lock to prevent concurrent 'single conversion' requests through
@@ -322,11 +355,17 @@ static int at91_adc_configure_trigger(struct iio_trigger *trig, bool state)
 		if (state) {
 			at91_adc_writel(st, AT91_SAMA5D2_CHER,
 					BIT(chan->channel));
-			at91_adc_writel(st, AT91_SAMA5D2_IER,
-					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 {
-			at91_adc_writel(st, AT91_SAMA5D2_IDR,
-					BIT(chan->channel));
+			/* 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));
 		}
@@ -340,6 +379,10 @@ 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 */
@@ -350,6 +393,153 @@ static int at91_adc_reenable_trigger(struct iio_trigger *trig)
 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 = indio_dev->channels + bit;
+
+		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;
+
+	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;
+
+	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 = indio_dev-&g