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()
  ...

13 files changed, 955 insertions, 297 deletions

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->channels + bit;
+
+		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,
@@ -388,24 +578,77 @@ static int at91_adc_trigger_init(struct iio_dev *indio)
 	return 0;
 }
 
-static irqreturn_t at91_adc_trigger_handler(int irq, void *p)
+static void at91_adc_trigger_handler_nodma(struct iio_dev *indio_dev,
+					   struct iio_poll_func *pf)
 {
-	struct iio_poll_func *pf = p;
-	struct iio_dev *indio = pf->indio_dev;
-	struct at91_adc_state *st = iio_priv(indio);
+	struct at91_adc_state *st = iio_priv(indio_dev);
 	int i = 0;
 	u8 bit;
 
-	for_each_set_bit(bit, indio->active_scan_mask, indio->num_channels) {
-		struct iio_chan_spec const *chan = indio->channels + bit;
+	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->buffer[i] = at91_adc_readl(st, chan->address);
 		i++;
 	}
+	iio_push_to_buffers_with_timestamp(indio_dev, st->buffer,
+					   pf->timestamp);
+}
 
-	iio_push_to_buffers_with_timestamp(indio, 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);
 
-	iio_trigger_notify_done(indio->trig);
+	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) {
+		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;
 }
@@ -414,7 +657,7 @@ static int at91_adc_buffer_init(struct iio_dev *indio)
 {
 	return devm_iio_triggered_buffer_setup(&indio->dev, indio,
 			&iio_pollfunc_store_time,
-			&at91_adc_trigger_handler, NULL);
+			&at91_adc_trigger_handler, &at91_buffer_setup_ops);
 }
 
 static unsigned at91_adc_startup_time(unsigned startup_time_min,
@@ -485,10 +728,13 @@ static irqreturn_t at91_adc_interrupt(int irq, void *private)
 	if (!(status & imr))
 		return IRQ_NONE;
 
-	if (iio_buffer_enabled(indio)) {
+	if (iio_buffer_enabled(indio) && !st->dma_st.dma_chan) {
 		disable_irq_nosync(irq);
 		iio_trigger_poll(indio->trig);
-	} else {
+	} else if (iio_buffer_enabled(indio) && st->dma_st.dma_chan) {
+		disable_irq_nosync(irq);
+		WARN(true, "Unexpected irq occurred\n");
+	} else if (!iio_buffer_enabled(indio)) {
 		st->conversion_value = at91_adc_readl(st, st->chan->address);
 		st->conversion_done = true;
 		wake_up_interruptible(&st->wq_data_available);
@@ -510,7 +756,6 @@ static int at91_adc_read_raw(struct iio_dev *indio_dev,
 		ret = iio_device_claim_direct_mode(indio_dev);
 		if (ret)
 			return ret;
-
 		mutex_lock(&st->lock);
 
 		st->chan = chan;
@@ -541,6 +786,9 @@ static int at91_adc_read_raw(struct iio_dev *indio_dev,
 		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);
@@ -580,9 +828,123 @@ static int at91_adc_write_raw(struct iio_dev *indio_dev,
 	return 0;
 }
 
+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 const struct iio_info at91_adc_info = {
 	.read_raw = &at91_adc_read_raw,
 	.write_raw = &at91_adc_write_raw,
+	.hwfifo_set_watermark = &at91_adc_set_watermark,
 };
 
 static void at91_adc_hw_init(struct at91_adc_state *st)
@@ -599,6 +961,42 @@ static void at91_adc_hw_init(struct at91_adc_state *st)
 	at91_adc_setup_samp_freq(st, st->soc_info.min_sample_rate);
 }
 
+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 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 int at91_adc_probe(struct platform_device *pdev)
 {
 	struct iio_dev *indio_dev;
@@ -674,6 +1072,9 @@ static int at91_adc_probe(struct platform_device *pdev)
 	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);
@@ -737,11 +1138,22 @@ static int at91_adc_probe(struct platform_device *pdev)
 			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 per_clk_disable_unprepare;
+		goto dma_disable;
 
 	if (st->selected_trig->hw_trig)
 		dev_info(&pdev->dev, "setting up trigger as %s\n",
@@ -752,6 +1164,8 @@ static int at91_adc_probe(struct platform_device *pdev)
 
 	return 0;
 
+dma_disable:
+	at91_adc_dma_disable(pdev);
 per_clk_disable_unprepare:
 	clk_disable_unprepare(st->per_clk);
 vref_disable:
@@ -768,6 +1182,8 @@ static int at91_adc_remove(struct platform_device *pdev)
 
 	iio_device_unregister(indio_dev);
 
+	at91_adc_dma_disable(pdev);
+
 	clk_disable_unprepare(st->per_clk);
 
 	regulator_disable(st->vref);
diff --git a/drivers/iio/adc/at91_adc.c b/drivers/iio/adc/at91_adc.c
index 3836d4222a3e..71a5ee652b79 100644
--- a/drivers/iio/adc/at91_adc.c
+++ b/drivers/iio/adc/at91_adc.c
@@ -1177,9 +1177,9 @@ static int at91_adc_probe(struct platform_device *pdev)
 	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 
 	st->reg_base = devm_ioremap_resource(&pdev->dev, res);
-	if (IS_ERR(st->reg_base)) {
+	if (IS_ERR(st->reg_base))
 		return PTR_ERR(st->reg_base);
-	}
+
 
 	/*
 	 * Disable all IRQs before setting up the handler
diff --git a/drivers/iio/adc/axp288_adc.c b/drivers/iio/adc/axp288_adc.c
index 60c9e853dd81..031d568b4972 100644
--- a/drivers/iio/adc/axp288_adc.c
+++ b/drivers/iio/adc/axp288_adc.c
@@ -92,22 +92,14 @@ static const struct iio_chan_spec axp288_adc_channels[] = {
 	},
 };
 
-#define AXP288_ADC_MAP(_adc_channel_label, _consumer_dev_name,	\
-		_consumer_channel)				\
-	{							\
-		.adc_channel_label = _adc_channel_label,	\
-		.consumer_dev_name = _consumer_dev_name,	\
-		.consumer_channel = _consumer_channel,		\
-	}
-
 /* for consumer drivers */
 static struct iio_map axp288_adc_default_maps[] = {
-	AXP288_ADC_MAP("TS_PIN", "axp288-batt", "axp288-batt-temp"),
-	AXP288_ADC_MAP("PMIC_TEMP", "axp288-pmic", "axp288-pmic-temp"),
-	AXP288_ADC_MAP("GPADC", "axp288-gpadc", "axp288-system-temp"),
-	AXP288_ADC_MAP("BATT_CHG_I", "axp288-chrg", "axp288-chrg-curr"),
-	AXP288_ADC_MAP("BATT_DISCHRG_I", "axp288-chrg", "axp288-chrg-d-curr"),
-	AXP288_ADC_MAP("BATT_V", "axp288-batt", "axp288-batt-volt"),
+	IIO_MAP("TS_PIN", "axp288-batt", "axp288-batt-temp"),
+	IIO_MAP("PMIC_TEMP", "axp288-pmic", "axp288-pmic-temp"),
+	IIO_MAP("GPADC", "axp288-gpadc", "axp288-system-temp"),
+	IIO_MAP("BATT_CHG_I", "axp288-chrg", "axp288-chrg-curr"),
+	IIO_MAP("BATT_DISCHRG_I", "axp288-chrg", "axp288-chrg-d-curr"),
+	IIO_MAP("BATT_V", "axp288-batt", "axp288-batt-volt"),
 	{},
 };
 
diff --git a/drivers/iio/adc/hx711.c b/drivers/iio/adc/hx711.c
index d10b9f13d557..9430b54121e0 100644
--- a/drivers/iio/adc/hx711.c
+++ b/drivers/iio/adc/hx711.c
@@ -24,6 +24,9 @@
 #include <linux/delay.h>
 #include <linux/iio/iio.h>
 #include <linux/iio/sysfs.h>
+#include <linux/iio/buffer.h>
+#include <linux/iio/trigger_consumer.h>
+#include <linux/iio/triggered_buffer.h>
 #include <linux/gpio/consumer.h>
 #include <linux/regulator/consumer.h>
 
@@ -89,6 +92,11 @@ struct hx711_data {
 	int			gain_set;	/* gain set on device */
 	int			gain_chan_a;	/* gain for channel A */
 	struct mutex		lock;
+	/*
+	 * triggered buffer
+	 * 2x32-bit channel + 64-bit timestamp
+	 */
+	u32			buffer[4];
 };
 
 static int hx711_cycle(struct hx711_data *hx711_data)
@@ -145,15 +153,16 @@ static int hx711_wait_for_ready(struct hx711_data *hx711_data)
 	int i, val;
 
 	/*
-	 * a maximum reset cycle time of 56 ms was measured.
-	 * we round it up to 100 ms
+	 * in some rare cases the reset takes quite a long time
+	 * especially when the channel is changed.
+	 * Allow up to one second for it
 	 */
 	for (i = 0; i < 100; i++) {
 		val = gpiod_get_value(hx711_data->gpiod_dout);
 		if (!val)
 			break;
-		/* sleep at least 1 ms */
-		msleep(1);
+		/* sleep at least 10 ms */
+		msleep(10);
 	}
 	if (val)
 		return -EIO;
@@ -195,9 +204,7 @@ static int hx711_reset(struct hx711_data *hx711_data)
 		 * after a dummy read we need to wait vor readiness
 		 * for not mixing gain pulses with the clock
 		 */
-		ret = hx711_wait_for_ready(hx711_data);
-		if (ret)
-			return ret;
+		val = hx711_wait_for_ready(hx711_data);
 	}
 
 	return val;
@@ -236,34 +243,40 @@ static int hx711_set_gain_for_channel(struct hx711_data *hx711_data, int chan)
 	return 0;
 }
 
+static int hx711_reset_read(struct hx711_data *hx711_data, int chan)
+{
+	int ret;
+	int val;
+
+	/*
+	 * hx711_reset() must be called from here
+	 * because it could be calling hx711_read() by itself
+	 */
+	if (hx711_reset(hx711_data)) {
+		dev_err(hx711_data->dev, "reset failed!");
+		return -EIO;
+	}
+
+	ret = hx711_set_gain_for_channel(hx711_data, chan);
+	if (ret < 0)
+		return ret;
+
+	val = hx711_read(hx711_data);
+
+	return val;
+}
+
 static int hx711_read_raw(struct iio_dev *indio_dev,
 				const struct iio_chan_spec *chan,
 				int *val, int *val2, long mask)
 {
 	struct hx711_data *hx711_data = iio_priv(indio_dev);
-	int ret;
 
 	switch (mask) {
 	case IIO_CHAN_INFO_RAW:
 		mutex_lock(&hx711_data->lock);
 
-		/*
-		 * hx711_reset() must be called from here
-		 * because it could be calling hx711_read() by itself
-		 */
-		if (hx711_reset(hx711_data)) {
-			mutex_unlock(&hx711_data->lock);
-			dev_err(hx711_data->dev, "reset failed!");
-			return -EIO;
-		}
-
-		ret = hx711_set_gain_for_channel(hx711_data, chan->channel);
-		if (ret < 0) {
-			mutex_unlock(&hx711_data->lock);
-			return ret;
-		}
-
-		*val = hx711_read(hx711_data);
+		*val = hx711_reset_read(hx711_data, chan->channel);
 
 		mutex_unlock(&hx711_data->lock);
 
@@ -339,6 +352,36 @@ static int hx711_write_raw_get_fmt(struct iio_dev *indio_dev,
 	return IIO_VAL_INT_PLUS_NANO;
 }
 
+static irqreturn_t hx711_trigger(int irq, void *p)
+{
+	struct iio_poll_func *pf = p;
+	struct iio_dev *indio_dev = pf->indio_dev;
+	struct hx711_data *hx711_data = iio_priv(indio_dev);
+	int i, j = 0;
+
+	mutex_lock(&hx711_data->lock);
+
+	memset(hx711_data->buffer, 0, sizeof(hx711_data->buffer));
+
+	for (i = 0; i < indio_dev->masklength; i++) {
+		if (!test_bit(i, indio_dev->active_scan_mask))
+			continue;
+
+		hx711_data->buffer[j] = hx711_reset_read(hx711_data,
+					indio_dev->channels[i].channel);
+		j++;
+	}
+
+	iio_push_to_buffers_with_timestamp(indio_dev, hx711_data->buffer,
+							pf->timestamp);
+
+	mutex_unlock(&hx711_data->lock);
+
+	iio_trigger_notify_done(indio_dev->trig);
+
+	return IRQ_HANDLED;
+}
+
 static ssize_t hx711_scale_available_show(struct device *dev,
 				struct device_attribute *attr,
 				char *buf)
@@ -387,6 +430,13 @@ static const struct iio_chan_spec hx711_chan_spec[] = {
 		.indexed = 1,
 		.info_mask_separate = BIT(IIO_CHAN_INFO_RAW),
 		.info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE),
+		.scan_index = 0,
+		.scan_type = {
+			.sign = 'u',
+			.realbits = 24,
+			.storagebits = 32,
+			.endianness = IIO_CPU,
+		},
 	},
 	{
 		.type = IIO_VOLTAGE,
@@ -394,7 +444,15 @@ static const struct iio_chan_spec hx711_chan_spec[] = {
 		.indexed = 1,
 		.info_mask_separate = BIT(IIO_CHAN_INFO_RAW),
 		.info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE),
+		.scan_index = 1,
+		.scan_type = {
+			.sign = 'u',
+			.realbits = 24,
+			.storagebits = 32,
+			.endianness = IIO_CPU,
+		},
 	},
+	IIO_CHAN_SOFT_TIMESTAMP(2),
 };
 
 static int hx711_probe(struct platform_device *pdev)
@@ -459,10 +517,9 @@ static int hx711_probe(struct platform_device *pdev)
 	 * 1 LSB = (AVDD * 100) / GAIN / 1678 [10^-9 mV]
 	 */
 	ret = regulator_get_voltage(hx711_data->reg_avdd);
-	if (ret < 0) {
-		regulator_disable(hx711_data->reg_avdd);
-		return ret;
-	}
+	if (ret < 0)
+		goto error_regulator;
+
 	/* we need 10^-9 mV */
 	ret *= 100;
 
@@ -482,12 +539,27 @@ static int hx711_probe(struct platform_device *pdev)
 	indio_dev->channels = hx711_chan_spec;
 	indio_dev->num_channels = ARRAY_SIZE(hx711_chan_spec);
 
+	ret = iio_triggered_buffer_setup(indio_dev, iio_pollfunc_store_time,
+							hx711_trigger, NULL);
+	if (ret < 0) {
+		dev_err(dev, "setup of iio triggered buffer failed\n");
+		goto error_regulator;
+	}
+
 	ret = iio_device_register(indio_dev);
 	if (ret < 0) {
 		dev_err(dev, "Couldn't register the device\n");
-		regulator_disable(hx711_data->reg_avdd);
+		goto error_buffer;
 	}
 
+	return 0;
+
+error_buffer:
+	iio_triggered_buffer_cleanup(indio_dev);
+
+error_regulator:
+	regulator_disable(hx711_data->reg_avdd);
+
 	return ret;
 }
 
@@ -501,6 +573,8 @@ static int hx711_remove(struct platform_device *pdev)
 
 	iio_device_unregister(indio_dev);
 
+	iio_triggered_buffer_cleanup(indio_dev);
+
 	regulator_disable(hx711_data->reg_avdd);
 
 	return 0;
diff --git a/drivers/iio/adc/ina2xx-adc.c b/drivers/iio/adc/ina2xx-adc.c
index 84a43871f7dc..0635a79864bf 100644
--- a/drivers/iio/adc/ina2xx-adc.c
+++ b/drivers/iio/adc/ina2xx-adc.c
@@ -44,13 +44,14 @@
 
 #define INA226_MASK_ENABLE		0x06
 #define INA226_CVRF			BIT(3)
-#define INA219_CNVR			BIT(1)
 
 #define INA2XX_MAX_REGISTERS            8
 
 /* settings - depend on use case */
-#define INA219_CONFIG_DEFAULT           0x399F	/* PGA=8 */
+#define INA219_CONFIG_DEFAULT           0x399F	/* PGA=1/8, BRNG=32V */
 #define INA219_DEFAULT_IT		532
+#define INA219_DEFAULT_BRNG             1   /* 32V */
+#define INA219_DEFAULT_PGA              125 /* 1000/8 */
 #define INA226_CONFIG_DEFAULT           0x4327
 #define INA226_DEFAULT_AVG              4
 #define INA226_DEFAULT_IT		1110
@@ -63,6 +64,14 @@
  */
 #define INA2XX_MODE_MASK	GENMASK(3, 0)
 
+/* Gain for VShunt: 1/8 (default), 1/4, 1/2, 1 */
+#define INA219_PGA_MASK		GENMASK(12, 11)
+#define INA219_SHIFT_PGA(val)	((val) << 11)
+
+/* VBus range: 32V (default), 16V */
+#define INA219_BRNG_MASK	BIT(13)
+#define INA219_SHIFT_BRNG(val)	((val) << 13)
+
 /* Averaging for VBus/VShunt/Power */
 #define INA226_AVG_MASK		GENMASK(11, 9)
 #define INA226_SHIFT_AVG(val)	((val) << 9)
@@ -79,6 +88,11 @@
 #define INA226_ITS_MASK		GENMASK(5, 3)
 #define INA226_SHIFT_ITS(val)	((val) << 3)
 
+/* INA219 Bus voltage register, low bits are flags */
+#define INA219_OVF		BIT(0)
+#define INA219_CNVR		BIT(1)
+#define INA219_BUS_VOLTAGE_SHIFT	3
+
 /* Cosmetic macro giving the sampling period for a full P=UxI cycle */
 #define SAMPLING_PERIOD(c)	((c->int_time_vbus + c->int_time_vshunt) \
 				 * c->avg)
@@ -110,11 +124,12 @@ enum ina2xx_ids { ina219, ina226 };
 
 struct ina2xx_config {
 	u16 config_default;
-	int calibration_factor;
-	int shunt_div;
-	int bus_voltage_shift;
+	int calibration_value;
+	int shunt_voltage_lsb;	/* nV */
+	int bus_voltage_shift;	/* position of lsb */
 	int bus_voltage_lsb;	/* uV */
-	int power_lsb;		/* uW */
+	/* fixed relation between current and power lsb, uW/uA */
+	int power_lsb_factor;
 	enum ina2xx_ids chip_id;
 };
 
@@ -127,26 +142,28 @@ struct ina2xx_chip_info {
 	int avg;
 	int int_time_vbus; /* Bus voltage integration time uS */
 	int int_time_vshunt; /* Shunt voltage integration time uS */
+	int range_vbus; /* Bus voltage maximum in V */
+	int pga_gain_vshunt; /* Shunt voltage PGA gain */
 	bool allow_async_readout;
 };
 
 static const struct ina2xx_config ina2xx_config[] = {
 	[ina219] = {
 		.config_default = INA219_CONFIG_DEFAULT,
-		.calibration_factor = 40960000,
-		.shunt_div = 100,
-		.bus_voltage_shift = 3,
+		.calibration_value = 4096,
+		.shunt_voltage_lsb = 10000,
+		.bus_voltage_shift = INA219_BUS_VOLTAGE_SHIFT,
 		.bus_voltage_lsb = 4000,
-		.power_lsb = 20000,
+		.power_lsb_factor = 20,
 		.chip_id = ina219,
 	},
 	[ina226] = {
 		.config_default = INA226_CONFIG_DEFAULT,
-		.calibration_factor = 5120000,
-		.shunt_div = 400,
+		.calibration_value = 2048,
+		.shunt_voltage_lsb = 2500,
 		.bus_voltage_shift = 0,
 		.bus_voltage_lsb = 1250,
-		.power_lsb = 25000,
+		.power_lsb_factor = 25,
 		.chip_id = ina226,
 	},
 };
@@ -170,6 +187,9 @@ static int ina2xx_read_raw(struct iio_dev *indio_dev,
 		else
 			*val  = regval;
 
+		if (chan->address == INA2XX_BUS_VOLTAGE)
+			*val >>= chip->config->bus_voltage_shift;
+
 		return IIO_VAL_INT;
 
 	case IIO_CHAN_INFO_OVERSAMPLING_RATIO:
@@ -197,26 +217,48 @@ static int ina2xx_read_raw(struct iio_dev *indio_dev,
 	case IIO_CHAN_INFO_SCALE:
 		switch (chan->address) {
 		case INA2XX_SHUNT_VOLTAGE:
-			/* processed (mV) = raw/shunt_div */
-			*val2 = chip->config->shunt_div;
-			*val = 1;
+			/* processed (mV) = raw * lsb(nV) / 1000000 */
+			*val = chip->config->shunt_voltage_lsb;
+			*val2 = 1000000;
 			return IIO_VAL_FRACTIONAL;
 
 		case INA2XX_BUS_VOLTAGE:
-			/* processed (mV) = raw*lsb (uV) / (1000 << shift) */
+			/* processed (mV) = raw * lsb (uV) / 1000 */
 			*val = chip->config->bus_voltage_lsb;
-			*val2 = 1000 << chip->config->bus_voltage_shift;
+			*val2 = 1000;
+			return IIO_VAL_FRACTIONAL;
+
+		case INA2XX_CURRENT:
+			/*
+			 * processed (mA) = raw * current_lsb (mA)
+			 * current_lsb (mA) = shunt_voltage_lsb (nV) /
+			 *                    shunt_resistor (uOhm)
+			 */
+			*val = chip->config->shunt_voltage_lsb;
+			*val2 = chip->shunt_resistor_uohm;
 			return IIO_VAL_FRACTIONAL;
 
 		case INA2XX_POWER:
-			/* processed (mW) = raw*lsb (uW) / 1000 */
-			*val = chip->config->power_lsb;
+			/*
+			 * processed (mW) = raw * power_lsb (mW)
+			 * power_lsb (mW) = power_lsb_factor (mW/mA) *
+			 *                  current_lsb (mA)
+			 */
+			*val = chip->config->power_lsb_factor *
+			       chip->config->shunt_voltage_lsb;
+			*val2 = chip->shunt_resistor_uohm;
+			return IIO_VAL_FRACTIONAL;
+		}
+
+	case IIO_CHAN_INFO_HARDWAREGAIN:
+		switch (chan->address) {
+		case INA2XX_SHUNT_VOLTAGE:
+			*val = chip->pga_gain_vshunt;
 			*val2 = 1000;
 			return IIO_VAL_FRACTIONAL;
 
-		case INA2XX_CURRENT:
-			/* processed (mA) = raw (mA) */
-			*val = 1;
+		case INA2XX_BUS_VOLTAGE:
+			*val = chip->range_vbus == 32 ? 1 : 2;
 			return IIO_VAL_INT;
 		}
 	}
@@ -353,6 +395,74 @@ static int ina219_set_int_time_vshunt(struct ina2xx_chip_info *chip,
 	return 0;
 }
 
+static const int ina219_vbus_range_tab[] = { 1, 2 };
+static int ina219_set_vbus_range_denom(struct ina2xx_chip_info *chip,
+				       unsigned int range,
+				       unsigned int *config)
+{
+	if (range == 1)
+		chip->range_vbus = 32;
+	else if (range == 2)
+		chip->range_vbus = 16;
+	else
+		return -EINVAL;
+
+	*config &= ~INA219_BRNG_MASK;
+	*config |= INA219_SHIFT_BRNG(range == 1 ? 1 : 0) & INA219_BRNG_MASK;
+
+	return 0;
+}
+
+static const int ina219_vshunt_gain_tab[] = { 125, 250, 500, 1000 };
+static const int ina219_vshunt_gain_frac[] = {
+	125, 1000, 250, 1000, 500, 1000, 1000, 1000 };
+
+static int ina219_set_vshunt_pga_gain(struct ina2xx_chip_info *chip,
+				      unsigned int gain,
+				      unsigned int *config)
+{
+	int bits;
+
+	if (gain < 125 || gain > 1000)
+		return -EINVAL;
+
+	bits = find_closest(gain, ina219_vshunt_gain_tab,
+			    ARRAY_SIZE(ina219_vshunt_gain_tab));
+
+	chip->pga_gain_vshunt = ina219_vshunt_gain_tab[bits];
+	bits = 3 - bits;
+
+	*config &= ~INA219_PGA_MASK;
+	*config |= INA219_SHIFT_PGA(bits) & INA219_PGA_MASK;
+
+	return 0;
+}
+
+static int ina2xx_read_avail(struct iio_dev *indio_dev,
+			     struct iio_chan_spec const *chan,
+			     const int **vals, int *type, int *length,
+			     long mask)
+{
+	switch (mask) {
+	case IIO_CHAN_INFO_HARDWAREGAIN:
+		switch (chan->address) {
+		case INA2XX_SHUNT_VOLTAGE:
+			*type = IIO_VAL_FRACTIONAL;
+			*length = sizeof(ina219_vshunt_gain_frac) / sizeof(int);
+			*vals = ina219_vshunt_gain_frac;
+			return IIO_AVAIL_LIST;
+
+		case INA2XX_BUS_VOLTAGE:
+			*type = IIO_VAL_INT;
+			*length = sizeof(ina219_vbus_range_tab) / sizeof(int);
+			*vals = ina219_vbus_range_tab;
+			return IIO_AVAIL_LIST;
+		}
+	}
+
+	return -EINVAL;
+}
+
 static int ina2xx_write_raw(struct iio_dev *indio_dev,
 			    struct iio_chan_spec const *chan,
 			    int val, int val2, long mask)
@@ -395,6 +505,14 @@ static int ina2xx_write_raw(struct iio_dev *indio_dev,
 		}
 		break;
 
+	case IIO_CHAN_INFO_HARDWAREGAIN:
+		if (chan->address == INA2XX_SHUNT_VOLTAGE)
+			ret = ina219_set_vshunt_pga_gain(chip, val * 1000 +
+							 val2 / 1000, &tmp);
+		else
+			ret = ina219_set_vbus_range_denom(chip, val, &tmp);
+		break;
+
 	default:
 		ret = -EINVAL;
 	}
@@ -434,25 +552,21 @@ static ssize_t ina2xx_allow_async_readout_store(struct device *dev,
 }
 
 /*
- * Set current LSB to 1mA, shunt is in uOhms
- * (equation 13 in datasheet). We hardcode a Current_LSB
- * of 1.0 x10-3. The only remaining parameter is RShunt.
- * There is no need to expose the CALIBRATION register
- * to the user for now. But we need to reset this register
- * if the user updates RShunt after driver init, e.g upon
- * reading an EEPROM/Probe-type value.
+ * Calibration register is set to the best value, which eliminates
+ * truncation errors on calculating current register in hardware.
+ * According to datasheet (INA 226: eq. 3, INA219: eq. 4) the best values
+ * are 2048 for ina226 and 4096 for ina219. They are hardcoded as
+ * calibration_value.
  */
 static int ina2xx_set_calibration(struct ina2xx_chip_info *chip)
 {
-	u16 regval = DIV_ROUND_CLOSEST(chip->config->calibration_factor,
-				   chip->shunt_resistor_uohm);
-
-	return regmap_write(chip->regmap, INA2XX_CALIBRATION, regval);
+	return regmap_write(chip->regmap, INA2XX_CALIBRATION,
+			    chip->config->calibration_value);
 }
 
 static int set_shunt_resistor(struct ina2xx_chip_info *chip, unsigned int val)
 {
-	if (val <= 0 || val > chip->config->calibration_factor)
+	if (val == 0 || val > INT_MAX)
 		return -EINVAL;
 
 	chip->shunt_resistor_uohm = val;
@@ -485,11 +599,6 @@ static ssize_t ina2xx_shunt_resistor_store(struct device *dev,
 	if (ret)
 		return ret;
 
-	/* Update the Calibration register */
-	ret = ina2xx_set_calibration(chip);
-	if (ret)
-		return ret;
-
 	return len;
 }
 
@@ -532,19 +641,23 @@ static ssize_t ina2xx_shunt_resistor_store(struct device *dev,
  * Sampling Freq is a consequence of the integration times of
  * the Voltage channels.
  */
-#define INA219_CHAN_VOLTAGE(_index, _address) { \
+#define INA219_CHAN_VOLTAGE(_index, _address, _shift) { \
 	.type = IIO_VOLTAGE, \
 	.address = (_address), \
 	.indexed = 1, \
 	.channel = (_index), \
 	.info_mask_separate = BIT(IIO_CHAN_INFO_RAW) | \
 			      BIT(IIO_CHAN_INFO_SCALE) | \
-			      BIT(IIO_CHAN_INFO_INT_TIME), \
+			      BIT(IIO_CHAN_INFO_INT_TIME) | \
+			      BIT(IIO_CHAN_INFO_HARDWAREGAIN), \
+	.info_mask_separate_available = \
+			      BIT(IIO_CHAN_INFO_HARDWAREGAIN), \
 	.info_mask_shared_by_dir = BIT(IIO_CHAN_INFO_SAMP_FREQ), \
 	.scan_index = (_index), \
 	.scan_type = { \
 		.sign = 'u', \
-		.realbits = 16, \
+		.shift = _shift, \
+		.realbits = 16 - _shift, \
 		.storagebits = 16, \
 		.endianness = IIO_LE, \
 	} \
@@ -579,23 +692,18 @@ static const struct iio_chan_spec ina226_channels[] = {
 };
 
 static const struct iio_chan_spec ina219_channels[] = {
-	INA219_CHAN_VOLTAGE(0, INA2XX_SHUNT_VOLTAGE),
-	INA219_CHAN_VOLTAGE(1, INA2XX_BUS_VOLTAGE),
+	INA219_CHAN_VOLTAGE(0, INA2XX_SHUNT_VOLTAGE, 0),
+	INA219_CHAN_VOLTAGE(1, INA2XX_BUS_VOLTAGE, INA219_BUS_VOLTAGE_SHIFT),
 	INA219_CHAN(IIO_POWER, 2, INA2XX_POWER),
 	INA219_CHAN(IIO_CURRENT, 3, INA2XX_CURRENT),
 	IIO_CHAN_SOFT_TIMESTAMP(4),
 };
 
-static int ina2xx_work_buffer(struct iio_dev *indio_dev)
+static int ina2xx_conversion_ready(struct iio_dev *indio_dev)
 {
 	struct ina2xx_chip_info *chip = iio_priv(indio_dev);
-	unsigned short data[8];
-	int bit, ret, i = 0;
-	s64 time_a, time_b;
+	int ret;
 	unsigned int alert;
-	int cnvr_need_clear = 0;
-
-	time_a = iio_get_time_ns(indio_dev);
 
 	/*
 	 * Because the timer thread and the chip conversion clock
@@ -608,23 +716,31 @@ static int ina2xx_work_buffer(struct iio_dev *indio_dev)
 	 * For now, we do an extra read of the MASK_ENABLE register (INA226)
 	 * resp. the BUS_VOLTAGE register (INA219).
 	 */
-	if (!chip->allow_async_readout)
-		do {
-			if (chip->config->chip_id == ina226) {
-				ret = regmap_read(chip->regmap,
-						  INA226_MASK_ENABLE, &alert);
-				alert &= INA226_CVRF;
-			} else {
-				ret = regmap_read(chip->regmap,
-						  INA2XX_BUS_VOLTAGE, &alert);
-				alert &= INA219_CNVR;
-				cnvr_need_clear = alert;
-			}
+	if (chip->config->chip_id == ina226) {
+		ret = regmap_read(chip->regmap,
+				  INA226_MASK_ENABLE, &alert);
+		alert &= INA226_CVRF;
+	} else {
+		ret = regmap_read(chip->regmap,
+				  INA2XX_BUS_VOLTAGE, &alert);
+		alert &= INA219_CNVR;
+	}
 
-			if (ret < 0)
-				return ret;
+	if (ret < 0)
+		return ret;
+
+	return !!alert;
+}
+
+static int ina2xx_work_buffer(struct iio_dev *indio_dev)
+{
+	struct ina2xx_chip_info *chip = iio_priv(indio_dev);
+	/* data buffer needs space for channel data and timestap */
+	unsigned short data[4 + sizeof(s64)/sizeof(short)];
+	int bit, ret, i = 0;
+	s64 time;
 
-		} while (!alert);
+	time = iio_get_time_ns(indio_dev);
 
 	/*
 	 * Single register reads: bulk_read will not work with ina226/219
@@ -640,26 +756,11 @@ static int ina2xx_work_buffer(struct iio_dev *indio_dev)
 			return ret;
 
 		data[i++] = val;
-
-		if (INA2XX_SHUNT_VOLTAGE + bit == INA2XX_POWER)
-			cnvr_need_clear = 0;
-	}
-
-	/* Dummy read on INA219 power register to clear CNVR flag */
-	if (cnvr_need_clear && chip->config->chip_id == ina219) {
-		unsigned int val;
-
-		ret = regmap_read(chip->regmap, INA2XX_POWER, &val);
-		if (ret < 0)
-			return ret;
 	}
 
-	time_b = iio_get_time_ns(indio_dev);
+	iio_push_to_buffers_with_timestamp(indio_dev, data, time);
 
-	iio_push_to_buffers_with_timestamp(indio_dev,
-					   (unsigned int *)data, time_a);
-
-	return (unsigned long)(time_b - time_a) / 1000;
+	return 0;
 };
 
 static int ina2xx_capture_thread(void *data)
@@ -667,7 +768,9 @@ static int ina2xx_capture_thread(void *data)
 	struct iio_dev *indio_dev = data;
 	struct ina2xx_chip_info *chip = iio_priv(indio_dev);
 	int sampling_us = SAMPLING_PERIOD(chip);
-	int buffer_us;
+	int ret;
+	struct timespec64 next, now, delta;
+	s64 delay_us;
 
 	/*
 	 * Poll a bit faster than the chip internal Fs, in case
@@ -676,13 +779,43 @@ static int ina2xx_capture_thread(void *data)
 	if (!chip->allow_async_readout)
 		sampling_us -= 200;
 
+	ktime_get_ts64(&next);
+
 	do {
-		buffer_us = ina2xx_work_buffer(indio_dev);
-		if (buffer_us < 0)
-			return buffer_us;
+		while (!chip->allow_async_readout) {
+			ret = ina2xx_conversion_ready(indio_dev);
+			if (ret < 0)
+				return ret;
 
-		if (sampling_us > buffer_us)
-			udelay(sampling_us - buffer_us);
+			/*
+			 * If the conversion was not yet finished,
+			 * reset the reference timestamp.
+			 */
+			if (ret == 0)
+				ktime_get_ts64(&next);
+			else
+				break;
+		}
+
+		ret = ina2xx_work_buffer(indio_dev);
+		if (ret < 0)
+			return ret;
+
+		ktime_get_ts64(&now);
+
+		/*
+		 * Advance the timestamp for the next poll by one sampling
+		 * interval, and sleep for the remainder (next - now)
+		 * In case "next" has already passed, the interval is added
+		 * multiple times, i.e. samples are dropped.
+		 */
+		do {
+			timespec64_add_ns(&next, 1000 * sampling_us);
+			delta = timespec64_sub(next, now);
+			delay_us = div_s64(timespec64_to_ns(&delta), 1000);
+		} while (delay_us <= 0);
+
+		usleep_range(delay_us, (delay_us * 3) >> 1);
 
 	} while (!kthread_should_stop());
 
@@ -746,7 +879,6 @@ static IIO_CONST_ATTR_NAMED(ina226_integration_time_available,
 			    integration_time_available,
 			    "0.000140 0.000204 0.000332 0.000588 0.001100 0.002116 0.004156 0.008244");
 
-
 static IIO_DEVICE_ATTR(in_allow_async_readout, S_IRUGO | S_IWUSR,
 		       ina2xx_allow_async_readout_show,
 		       ina2xx_allow_async_readout_store, 0);
@@ -780,6 +912,7 @@ static const struct attribute_group ina226_attribute_group = {
 static const struct iio_info ina219_info = {
 	.attrs = &ina219_attribute_group,
 	.read_raw = ina2xx_read_raw,
+	.read_avail = ina2xx_read_avail,
 	.write_raw = ina2xx_write_raw,
 	.debugfs_reg_access = ina2xx_debug_reg,
 };
@@ -860,6 +993,8 @@ static int ina2xx_probe(struct i2c_client *client,
 		chip->avg = 1;
 		ina219_set_int_time_vbus(chip, INA219_DEFAULT_IT, &val);
 		ina219_set_int_time_vshunt(chip, INA219_DEFAULT_IT, &val);
+		ina219_set_vbus_range_denom(chip, INA219_DEFAULT_BRNG, &val);
+		ina219_set_vshunt_pga_gain(chip, INA219_DEFAULT_PGA, &val);
 	}
 
 	ret = ina2xx_init(chip, val);
diff --git a/drivers/iio/adc/meson_saradc.c b/drivers/iio/adc/meson_saradc.c
index 36047147ce7c..29fa7736d80c 100644
--- a/drivers/iio/adc/meson_saradc.c
+++ b/drivers/iio/adc/meson_saradc.c
@@ -96,8 +96,8 @@
 	#define MESON_SAR_ADC_FIFO_RD_SAMPLE_VALUE_MASK		GENMASK(11, 0)
 
 #define MESON_SAR_ADC_AUX_SW					0x1c
-	#define MESON_SAR_ADC_AUX_SW_MUX_SEL_CHAN_MASK(_chan)	\
-					(GENMASK(10, 8) << (((_chan) - 2) * 2))
+	#define MESON_SAR_ADC_AUX_SW_MUX_SEL_CHAN_SHIFT(_chan)	\
+					(8 + (((_chan) - 2) * 3))
 	#define MESON_SAR_ADC_AUX_SW_VREF_P_MUX			BIT(6)
 	#define MESON_SAR_ADC_AUX_SW_VREF_N_MUX			BIT(5)
 	#define MESON_SAR_ADC_AUX_SW_MODE_SEL			BIT(4)
@@ -221,6 +221,7 @@ enum meson_sar_adc_chan7_mux_sel {
 
 struct meson_sar_adc_data {
 	bool					has_bl30_integration;
+	unsigned long				clock_rate;
 	u32					bandgap_reg;
 	unsigned int				resolution;
 	const char				*name;
@@ -233,7 +234,6 @@ struct meson_sar_adc_priv {
 	const struct meson_sar_adc_data		*data;
 	struct clk				*clkin;
 	struct clk				*core_clk;
-	struct clk				*sana_clk;
 	struct clk				*adc_sel_clk;
 	struct clk				*adc_clk;
 	struct clk_gate				clk_gate;
@@ -622,7 +622,7 @@ static int meson_sar_adc_clk_init(struct iio_dev *indio_dev,
 static int meson_sar_adc_init(struct iio_dev *indio_dev)
 {
 	struct meson_sar_adc_priv *priv = iio_priv(indio_dev);
-	int regval, ret;
+	int regval, i, ret;
 
 	/*
 	 * make sure we start at CH7 input since the other muxes are only used
@@ -677,6 +677,32 @@ static int meson_sar_adc_init(struct iio_dev *indio_dev)
 			   FIELD_PREP(MESON_SAR_ADC_DELAY_INPUT_DLY_SEL_MASK,
 				      1));
 
+	/*
+	 * set up the input channel muxes in MESON_SAR_ADC_CHAN_10_SW
+	 * (0 = SAR_ADC_CH0, 1 = SAR_ADC_CH1)
+	 */
+	regval = FIELD_PREP(MESON_SAR_ADC_CHAN_10_SW_CHAN0_MUX_SEL_MASK, 0);
+	regmap_update_bits(priv->regmap, MESON_SAR_ADC_CHAN_10_SW,
+			   MESON_SAR_ADC_CHAN_10_SW_CHAN0_MUX_SEL_MASK,
+			   regval);
+	regval = FIELD_PREP(MESON_SAR_ADC_CHAN_10_SW_CHAN1_MUX_SEL_MASK, 1);
+	regmap_update_bits(priv->regmap, MESON_SAR_ADC_CHAN_10_SW,
+			   MESON_SAR_ADC_CHAN_10_SW_CHAN1_MUX_SEL_MASK,
+			   regval);
+
+	/*
+	 * set up the input channel muxes in MESON_SAR_ADC_AUX_SW
+	 * (2 = SAR_ADC_CH2, 3 = SAR_ADC_CH3, ...) and enable
+	 * MESON_SAR_ADC_AUX_SW_YP_DRIVE_SW and
+	 * MESON_SAR_ADC_AUX_SW_XP_DRIVE_SW like the vendor driver.
+	 */
+	regval = 0;
+	for (i = 2; i <= 7; i++)
+		regval |= i << MESON_SAR_ADC_AUX_SW_MUX_SEL_CHAN_SHIFT(i);
+	regval |= MESON_SAR_ADC_AUX_SW_YP_DRIVE_SW;
+	regval |= MESON_SAR_ADC_AUX_SW_XP_DRIVE_SW;
+	regmap_write(priv->regmap, MESON_SAR_ADC_AUX_SW, regval);
+
 	ret = clk_set_parent(priv->adc_sel_clk, priv->clkin);
 	if (ret) {
 		dev_err(indio_dev->dev.parent,
@@ -684,7 +710,7 @@ static int meson_sar_adc_init(struct iio_dev *indio_dev)
 		return ret;
 	}
 
-	ret = clk_set_rate(priv->adc_clk, 1200000);
+	ret = clk_set_rate(priv->adc_clk, priv->data->clock_rate);
 	if (ret) {
 		dev_err(indio_dev->dev.parent,
 			"failed to set adc clock rate\n");
@@ -731,12 +757,6 @@ static int meson_sar_adc_hw_enable(struct iio_dev *indio_dev)
 		goto err_core_clk;
 	}
 
-	ret = clk_prepare_enable(priv->sana_clk);
-	if (ret) {
-		dev_err(indio_dev->dev.parent, "failed to enable sana clk\n");
-		goto err_sana_clk;
-	}
-
 	regval = FIELD_PREP(MESON_SAR_ADC_REG0_FIFO_CNT_IRQ_MASK, 1);
 	regmap_update_bits(priv->regmap, MESON_SAR_ADC_REG0,
 			   MESON_SAR_ADC_REG0_FIFO_CNT_IRQ_MASK, regval);
@@ -763,8 +783,6 @@ err_adc_clk:
 	regmap_update_bits(priv->regmap, MESON_SAR_ADC_REG3,
 			   MESON_SAR_ADC_REG3_ADC_EN, 0);
 	meson_sar_adc_set_bandgap(indio_dev, false);
-	clk_disable_unprepare(priv->sana_clk);
-err_sana_clk:
 	clk_disable_unprepare(priv->core_clk);
 err_core_clk:
 	regulator_disable(priv->vref);
@@ -790,7 +808,6 @@ static int meson_sar_adc_hw_disable(struct iio_dev *indio_dev)
 
 	meson_sar_adc_set_bandgap(indio_dev, false);
 
-	clk_disable_unprepare(priv->sana_clk);
 	clk_disable_unprepare(priv->core_clk);
 
 	regulator_disable(priv->vref);
@@ -866,6 +883,7 @@ static const struct iio_info meson_sar_adc_iio_info = {
 
 static const struct meson_sar_adc_data meson_sar_adc_meson8_data = {
 	.has_bl30_integration = false,
+	.clock_rate = 1150000,
 	.bandgap_reg = MESON_SAR_ADC_DELTA_10,
 	.regmap_config = &meson_sar_adc_regmap_config_meson8,
 	.resolution = 10,
@@ -874,6 +892,7 @@ static const struct meson_sar_adc_data meson_sar_adc_meson8_data = {
 
 static const struct meson_sar_adc_data meson_sar_adc_meson8b_data = {
 	.has_bl30_integration = false,
+	.clock_rate = 1150000,
 	.bandgap_reg = MESON_SAR_ADC_DELTA_10,
 	.regmap_config = &meson_sar_adc_regmap_config_meson8,
 	.resolution = 10,
@@ -882,6 +901,7 @@ static const struct meson_sar_adc_data meson_sar_adc_meson8b_data = {
 
 static const struct meson_sar_adc_data meson_sar_adc_gxbb_data = {
 	.has_bl30_integration = true,
+	.clock_rate = 1200000,
 	.bandgap_reg = MESON_SAR_ADC_REG11,
 	.regmap_config = &meson_sar_adc_regmap_config_gxbb,
 	.resolution = 10,
@@ -890,6 +910,7 @@ static const struct meson_sar_adc_data meson_sar_adc_gxbb_data = {
 
 static const struct meson_sar_adc_data meson_sar_adc_gxl_data = {
 	.has_bl30_integration = true,
+	.clock_rate = 1200000,
 	.bandgap_reg = MESON_SAR_ADC_REG11,
 	.regmap_config = &meson_sar_adc_regmap_config_gxbb,
 	.resolution = 12,
@@ -898,6 +919,7 @@ static const struct meson_sar_adc_data meson_sar_adc_gxl_data = {
 
 static const struct meson_sar_adc_data meson_sar_adc_gxm_data = {
 	.has_bl30_integration = true,
+	.clock_rate = 1200000,
 	.bandgap_reg = MESON_SAR_ADC_REG11,
 	.regmap_config = &meson_sar_adc_regmap_config_gxbb,
 	.resolution = 12,
@@ -993,16 +1015,6 @@ static int meson_sar_adc_probe(struct platform_device *pdev)
 		return PTR_ERR(priv->core_clk);
 	}
 
-	priv->sana_clk = devm_clk_get(&pdev->dev, "sana");
-	if (IS_ERR(priv->sana_clk)) {
-		if (PTR_ERR(priv->sana_clk) == -ENOENT) {
-			priv->sana_clk = NULL;
-		} else {
-			dev_err(&pdev->dev, "failed to get sana clk\n");
-			return PTR_ERR(priv->sana_clk);
-		}
-	}
-
 	priv->adc_clk = devm_clk_get(&pdev->dev, "adc_clk");
 	if (IS_ERR(priv->adc_clk)) {
 		if (PTR_ERR(priv->adc_clk) == -ENOENT) {
diff --git a/drivers/iio/adc/qcom-vadc-common.c b/drivers/iio/adc/qcom-vadc-common.c
index 47d24ae5462f..fe3d7826783c 100644
--- a/drivers/iio/adc/qcom-vadc-common.c
+++ b/drivers/iio/adc/qcom-vadc-common.c
@@ -5,6 +5,7 @@
 #include <linux/math64.h>
 #include <linux/log2.h>
 #include <linux/err.h>
+#include <linux/module.h>
 
 #include "qcom-vadc-common.h"
 
@@ -229,3 +230,6 @@ int qcom_vadc_decimation_from_dt(u32 value)
 	return __ffs64(value / VADC_DECIMATION_MIN);
 }
 EXPORT_SYMBOL(qcom_vadc_decimation_from_dt);
+
+MODULE_LICENSE("GPL v2");
+MODULE_DESCRIPTION("Qualcomm ADC common functionality");
diff --git a/drivers/iio/adc/stm32-adc-core.c b/drivers/iio/adc/stm32-adc-core.c
index 6aefef99f935..40be7d9fadbf 100644
--- a/drivers/iio/adc/stm32-adc-core.c
+++ b/drivers/iio/adc/stm32-adc-core.c
@@ -1,3 +1,4 @@
+// SPDX-License-Identifier: GPL-2.0
 /*
  * This file is part of STM32 ADC driver
  *
@@ -6,19 +7,6 @@
  *
  * Inspired from: fsl-imx25-tsadc
  *
- * License type: GPLv2
- *
- * This program is free software; you can redistribute it and/or modify it
- * under the terms of the GNU General Public License version 2 as published by
- * the Free Software Foundation.
- *
- * 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.
- *
- * You should have received a copy of the GNU General Public License along with
- * this program. If not, see <http://www.gnu.org/licenses/>.
  */
 
 #include <linux/clk.h>
diff --git a/drivers/iio/adc/stm32-adc-core.h b/drivers/iio/adc/stm32-adc-core.h
index 250ee958a669..8af507b3f32d 100644
--- a/drivers/iio/adc/stm32-adc-core.h
+++ b/drivers/iio/adc/stm32-adc-core.h
@@ -1,22 +1,10 @@
+/* SPDX-License-Identifier: GPL-2.0 */
 /*
  * This file is part of STM32 ADC driver
  *
  * Copyright (C) 2016, STMicroelectronics - All Rights Reserved
  * Author: Fabrice Gasnier <fabrice.gasnier@st.com>.
  *
- * License type: GPLv2
- *
- * This program is free software; you can redistribute it and/or modify it
- * under the terms of the GNU General Public License version 2 as published by
- * the Free Software Foundation.
- *
- * 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.
- *
- * You should have received a copy of the GNU General Public License along with
- * this program. If not, see <http://www.gnu.org/licenses/>.
  */
 
 #ifndef __STM32_ADC_H
diff --git a/drivers/iio/adc/stm32-adc.c b/drivers/iio/adc/stm32-adc.c
index c9d96f935dba..7f5def465340 100644
--- a/drivers/iio/adc/stm32-adc.c
+++ b/drivers/iio/adc/stm32-adc.c
@@ -1,22 +1,9 @@
+// SPDX-License-Identifier: GPL-2.0
 /*
  * This file is part of STM32 ADC driver
  *
  * Copyright (C) 2016, STMicroelectronics - All Rights Reserved
  * Author: Fabrice Gasnier <fabrice.gasnier@st.com>.
- *
- * License type: GPLv2
- *
- * This program is free software; you can redistribute it and/or modify it
- * under the terms of the GNU General Public License version 2 as published by
- * the Free Software Foundation.
- *
- * 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.
- *
- * You should have received a copy of the GNU General Public License along with
- * this program. If not, see <http://www.gnu.org/licenses/>.
  */
 
 #include <linux/clk.h>
@@ -92,6 +79,7 @@
 #define STM32H7_ADC_SQR3		0x38
 #define STM32H7_ADC_SQR4		0x3C
 #define STM32H7_ADC_DR			0x40
+#define STM32H7_ADC_DIFSEL		0xC0
 #define STM32H7_ADC_CALFACT		0xC4
 #define STM32H7_ADC_CALFACT2		0xC8
 
@@ -153,6 +141,8 @@ enum stm32h7_adc_dmngt {
 /* BOOST bit must be set on STM32H7 when ADC clock is above 20MHz */
 #define STM32H7_BOOST_CLKRATE		20000000UL
 
+#define STM32_ADC_CH_MAX		20	/* max number of channels */
+#define STM32_ADC_CH_SZ			10	/* max channel name size */
 #define STM32_ADC_MAX_SQ		16	/* SQ1..SQ16 */
 #define STM32_ADC_MAX_SMP		7	/* SMPx range is [0..7] */
 #define STM32_ADC_TIMEOUT_US		100000
@@ -297,9 +287,11 @@ struct stm32_adc_cfg {
  * @rx_buf:		dma rx buffer cpu address
  * @rx_dma_buf:		dma rx buffer bus address
  * @rx_buf_sz:		dma rx buffer size
+ * @difsel		bitmask to set single-ended/differential channel
  * @pcsel		bitmask to preselect channels on some devices
  * @smpr_val:		sampling time settings (e.g. smpr1 / smpr2)
  * @cal:		optional calibration data on some devices
+ * @chan_name:		channel name array
  */
 struct stm32_adc {
 	struct stm32_adc_common	*common;
@@ -318,72 +310,37 @@ struct stm32_adc {
 	u8			*rx_buf;
 	dma_addr_t		rx_dma_buf;
 	unsigned int		rx_buf_sz;
+	u32			difsel;
 	u32			pcsel;
 	u32			smpr_val[2];
 	struct stm32_adc_calib	cal;
+	char			chan_name[STM32_ADC_CH_MAX][STM32_ADC_CH_SZ];
 };
 
-/**
- * struct stm32_adc_chan_spec - specification of stm32 adc channel
- * @type:	IIO channel type
- * @channel:	channel number (single ended)
- * @name:	channel name (single ended)
- */
-struct stm32_adc_chan_spec {
-	enum iio_chan_type	type;
-	int			channel;
-	const char		*name;
+struct stm32_adc_diff_channel {
+	u32 vinp;
+	u32 vinn;
 };
 
 /**
  * struct stm32_adc_info - stm32 ADC, per instance config data
- * @channels:		Reference to stm32 channels spec
  * @max_channels:	Number of channels
  * @resolutions:	available resolutions
  * @num_res:		number of available resolutions
  */
 struct stm32_adc_info {
-	const struct stm32_adc_chan_spec *channels;
 	int max_channels;
 	const unsigned int *resolutions;
 	const unsigned int num_res;
 };
 
-/*
- * Input definitions common for all instances:
- * stm32f4 can have up to 16 channels
- * stm32h7 can have up to 20 channels
- */
-static const struct stm32_adc_chan_spec stm32_adc_channels[] = {
-	{ IIO_VOLTAGE, 0, "in0" },
-	{ IIO_VOLTAGE, 1, "in1" },
-	{ IIO_VOLTAGE, 2, "in2" },
-	{ IIO_VOLTAGE, 3, "in3" },
-	{ IIO_VOLTAGE, 4, "in4" },
-	{ IIO_VOLTAGE, 5, "in5" },
-	{ IIO_VOLTAGE, 6, "in6" },
-	{ IIO_VOLTAGE, 7, "in7" },
-	{ IIO_VOLTAGE, 8, "in8" },
-	{ IIO_VOLTAGE, 9, "in9" },
-	{ IIO_VOLTAGE, 10, "in10" },
-	{ IIO_VOLTAGE, 11, "in11" },
-	{ IIO_VOLTAGE, 12, "in12" },
-	{ IIO_VOLTAGE, 13, "in13" },
-	{ IIO_VOLTAGE, 14, "in14" },
-	{ IIO_VOLTAGE, 15, "in15" },
-	{ IIO_VOLTAGE, 16, "in16" },
-	{ IIO_VOLTAGE, 17, "in17" },
-	{ IIO_VOLTAGE, 18, "in18" },
-	{ IIO_VOLTAGE, 19, "in19" },
-};
-
 static const unsigned int stm32f4_adc_resolutions[] = {
 	/* sorted values so the index matches RES[1:0] in STM32F4_ADC_CR1 */
 	12, 10, 8, 6,
 };
 
+/* stm32f4 can have up to 16 channels */
 static const struct stm32_adc_info stm32f4_adc_info = {
-	.channels = stm32_adc_channels,
 	.max_channels = 16,
 	.resolutions = stm32f4_adc_resolutions,
 	.num_res = ARRAY_SIZE(stm32f4_adc_resolutions),
@@ -394,9 +351,9 @@ static const unsigned int stm32h7_adc_resolutions[] = {
 	16, 14, 12, 10, 8,
 };
 
+/* stm32h7 can have up to 20 channels */
 static const struct stm32_adc_info stm32h7_adc_info = {
-	.channels = stm32_adc_channels,
-	.max_channels = 20,
+	.max_channels = STM32_ADC_CH_MAX,
 	.resolutions = stm32h7_adc_resolutions,
 	.num_res = ARRAY_SIZE(stm32h7_adc_resolutions),
 };
@@ -983,15 +940,19 @@ pwr_dwn:
  * stm32h7_adc_prepare() - Leave power down mode to enable ADC.
  * @adc: stm32 adc instance
  * Leave power down mode.
+ * Configure channels as single ended or differential before enabling ADC.
  * Enable ADC.
  * Restore calibration data.
- * Pre-select channels that may be used in PCSEL (required by input MUX / IO).
+ * Pre-select channels that may be used in PCSEL (required by input MUX / IO):
+ * - Only one input is selected for single ended (e.g. 'vinp')
+ * - Two inputs are selected for differential channels (e.g. 'vinp' & 'vinn')
  */
 static int stm32h7_adc_prepare(struct stm32_adc *adc)
 {
 	int ret;
 
 	stm32h7_adc_exit_pwr_down(adc);
+	stm32_adc_writel(adc, STM32H7_ADC_DIFSEL, adc->difsel);
 
 	ret = stm32h7_adc_enable(adc);
 	if (ret)
@@ -1263,10 +1224,23 @@ static int stm32_adc_read_raw(struct iio_dev *indio_dev,
 		return ret;
 
 	case IIO_CHAN_INFO_SCALE:
-		*val = adc->common->vref_mv;
-		*val2 = chan->scan_type.realbits;
+		if (chan->differential) {
+			*val = adc->common->vref_mv * 2;
+			*val2 = chan->scan_type.realbits;
+		} else {
+			*val = adc->common->vref_mv;
+			*val2 = chan->scan_type.realbits;
+		}
 		return IIO_VAL_FRACTIONAL_LOG2;
 
+	case IIO_CHAN_INFO_OFFSET:
+		if (chan->differential)
+			/* ADC_full_scale / 2 */
+			*val = -((1 << chan->scan_type.realbits) / 2);
+		else
+			*val = 0;
+		return IIO_VAL_INT;
+
 	default:
 		return -EINVAL;
 	}
@@ -1315,6 +1289,7 @@ static int stm32_adc_set_watermark(struct iio_dev *indio_dev, unsigned int val)
 {
 	struct stm32_adc *adc = iio_priv(indio_dev);
 	unsigned int watermark = STM32_DMA_BUFFER_SIZE / 2;
+	unsigned int rx_buf_sz = STM32_DMA_BUFFER_SIZE;
 
 	/*
 	 * dma cyclic transfers are used, buffer is split into two periods.
@@ -1323,7 +1298,7 @@ static int stm32_adc_set_watermark(struct iio_dev *indio_dev, unsigned int val)
 	 * - one buffer (period) driver can push with iio_trigger_poll().
 	 */
 	watermark = min(watermark, val * (unsigned)(sizeof(u16)));
-	adc->rx_buf_sz = watermark * 2;
+	adc->rx_buf_sz = min(rx_buf_sz, watermark * 2 * adc->num_conv);
 
 	return 0;
 }
@@ -1628,29 +1603,40 @@ static void stm32_adc_smpr_init(struct stm32_adc *adc, int channel, u32 smp_ns)
 }
 
 static void stm32_adc_chan_init_one(struct iio_dev *indio_dev,
-				    struct iio_chan_spec *chan,
-				    const struct stm32_adc_chan_spec *channel,
-				    int scan_index, u32 smp)
+				    struct iio_chan_spec *chan, u32 vinp,
+				    u32 vinn, int scan_index, bool differential)
 {
 	struct stm32_adc *adc = iio_priv(indio_dev);
-
-	chan->type = channel->type;
-	chan->channel = channel->channel;
-	chan->datasheet_name = channel->name;
+	char *name = adc->chan_name[vinp];
+
+	chan->type = IIO_VOLTAGE;
+	chan->channel = vinp;
+	if (differential) {
+		chan->differential = 1;
+		chan->channel2 = vinn;
+		snprintf(name, STM32_ADC_CH_SZ, "in%d-in%d", vinp, vinn);
+	} else {
+		snprintf(name, STM32_ADC_CH_SZ, "in%d", vinp);
+	}
+	chan->datasheet_name = name;
 	chan->scan_index = scan_index;
 	chan->indexed = 1;
 	chan->info_mask_separate = BIT(IIO_CHAN_INFO_RAW);
-	chan->info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE);
+	chan->info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE) |
+					 BIT(IIO_CHAN_INFO_OFFSET);
 	chan->scan_type.sign = 'u';
 	chan->scan_type.realbits = adc->cfg->adc_info->resolutions[adc->res];
 	chan->scan_type.storagebits = 16;
 	chan->ext_info = stm32_adc_ext_info;
 
-	/* Prepare sampling time settings */
-	stm32_adc_smpr_init(adc, chan->channel, smp);
-
 	/* pre-build selected channels mask */
 	adc->pcsel |= BIT(chan->channel);
+	if (differential) {
+		/* pre-build diff channels mask */
+		adc->difsel |= BIT(chan->channel);
+		/* Also add negative input to pre-selected channels */
+		adc->pcsel |= BIT(chan->channel2);
+	}
 }
 
 static int stm32_adc_chan_of_init(struct iio_dev *indio_dev)
@@ -1658,17 +1644,40 @@ static int stm32_adc_chan_of_init(struct iio_dev *indio_dev)
 	struct device_node *node = indio_dev->dev.of_node;
 	struct stm32_adc *adc = iio_priv(indio_dev);
 	const struct stm32_adc_info *adc_info = adc->cfg->adc_info;
+	struct stm32_adc_diff_channel diff[STM32_ADC_CH_MAX];
 	struct property *prop;
 	const __be32 *cur;
 	struct iio_chan_spec *channels;
-	int scan_index = 0, num_channels, ret;
+	int scan_index = 0, num_channels = 0, num_diff = 0, ret, i;
 	u32 val, smp = 0;
 
-	num_channels = of_property_count_u32_elems(node, "st,adc-channels");
-	if (num_channels < 0 ||
-	    num_channels > adc_info->max_channels) {
+	ret = of_property_count_u32_elems(node, "st,adc-channels");
+	if (ret > adc_info->max_channels) {
 		dev_err(&indio_dev->dev, "Bad st,adc-channels?\n");
-		return num_channels < 0 ? num_channels : -EINVAL;
+		return -EINVAL;
+	} else if (ret > 0) {
+		num_channels += ret;
+	}
+
+	ret = of_property_count_elems_of_size(node, "st,adc-diff-channels",
+					      sizeof(*diff));
+	if (ret > adc_info->max_channels) {
+		dev_err(&indio_dev->dev, "Bad st,adc-diff-channels?\n");
+		return -EINVAL;
+	} else if (ret > 0) {
+		int size = ret * sizeof(*diff) / sizeof(u32);
+
+		num_diff = ret;
+		num_channels += ret;
+		ret = of_property_read_u32_array(node, "st,adc-diff-channels",
+						 (u32 *)diff, size);
+		if (ret)
+			return ret;
+	}
+
+	if (!num_channels) {
+		dev_err(&indio_dev->dev, "No channels configured\n");
+		return -ENODATA;
 	}
 
 	/* Optional sample time is provided either for each, or all channels */
@@ -1689,6 +1698,33 @@ static int stm32_adc_chan_of_init(struct iio_dev *indio_dev)
 			return -EINVAL;
 		}
 
+		/* Channel can't be configured both as single-ended & diff */
+		for (i = 0; i < num_diff; i++) {
+			if (val == diff[i].vinp) {
+				dev_err(&indio_dev->dev,
+					"channel %d miss-configured\n",	val);
+				return -EINVAL;
+			}
+		}
+		stm32_adc_chan_init_one(indio_dev, &channels[scan_index], val,
+					0, scan_index, false);
+		scan_index++;
+	}
+
+	for (i = 0; i < num_diff; i++) {
+		if (diff[i].vinp >= adc_info->max_channels ||
+		    diff[i].vinn >= adc_info->max_channels) {
+			dev_err(&indio_dev->dev, "Invalid channel in%d-in%d\n",
+				diff[i].vinp, diff[i].vinn);
+			return -EINVAL;
+		}
+		stm32_adc_chan_init_one(indio_dev, &channels[scan_index],
+					diff[i].vinp, diff[i].vinn, scan_index,
+					true);
+		scan_index++;
+	}
+
+	for (i = 0; i < scan_index; i++) {
 		/*
 		 * Using of_property_read_u32_index(), smp value will only be
 		 * modified if valid u32 value can be decoded. This allows to
@@ -1696,12 +1732,9 @@ static int stm32_adc_chan_of_init(struct iio_dev *indio_dev)
 		 * value per channel.
 		 */
 		of_property_read_u32_index(node, "st,min-sample-time-nsecs",
-					   scan_index, &smp);
-
-		stm32_adc_chan_init_one(indio_dev, &channels[scan_index],
-					&adc_info->channels[val],
-					scan_index, smp);
-		scan_index++;
+					   i, &smp);
+		/* Prepare sampling time settings */
+		stm32_adc_smpr_init(adc, channels[i].channel, smp);
 	}
 
 	indio_dev->num_channels = scan_index;
diff --git a/drivers/iio/adc/ti_am335x_adc.c b/drivers/iio/adc/ti_am335x_adc.c
index b3e573cc6f5f..80df5a377d30 100644
--- a/drivers/iio/adc/ti_am335x_adc.c
+++ b/drivers/iio/adc/ti_am335x_adc.c
@@ -523,7 +523,7 @@ static int tiadc_read_raw(struct iio_dev *indio_dev,
 	}
 	am335x_tsc_se_adc_done(adc_dev->mfd_tscadc);
 
-	if (found == false)
+	if (!found)
 		ret =  -EBUSY;
 
 err_unlock: