[PATCH v2 0/4] Add DMA support for ti_am335x_adc driver

[PATCH v2 0/4] Add DMA support for ti_am335x_adc driver

[Mugunthan V N]

The ADC has a 64 work depth fifo length which holds the ADC data
till the CPU reads. So when a user program needs a large ADC data
to operate on, then it has to do multiple reads to get its
buffer. Currently if the application asks for 4 samples per
channel with all 8 channels are enabled, kernel can provide only
3 samples per channel when all 8 channels are enabled (logs at
[1]). So with DMA support user can request for large number of
samples at a time (logs at [2]).

Tested the patch on AM437x-gp-evm and AM335x Boneblack with the
patch [3] to enable ADC and pushed a branch for testing [4]

Changes from Initial version:
* Changed DMA api from dma_request_slave_channel_compat() to
  dma_request_chan()
* Changed variable names to have more clear information as per
  comments from Peter.

[1] - http://pastebin.ubuntu.com/23211490/
[2] - http://pastebin.ubuntu.com/23269792/
[3] - http://pastebin.ubuntu.com/23211494/
[4] - git://git.ti.com/~mugunthanvnm/ti-linux-kernel/linux.git iio-dma-v2

Mugunthan V N (4):
  mfd: ti_am335x_tscadc: store physical address
  drivers: iio: ti_am335x_adc: add dma support
  ARM: dts: am33xx: add DMA properties for tscadc
  ARM: dts: am4372: add DMA properties for tscadc

 arch/arm/boot/dts/am33xx.dtsi        |   2 +
 arch/arm/boot/dts/am4372.dtsi        |   2 +
 drivers/iio/adc/ti_am335x_adc.c      | 145 ++++++++++++++++++++++++++++++++++-
 drivers/mfd/ti_am335x_tscadc.c       |   1 +
 include/linux/mfd/ti_am335x_tscadc.h |   8 ++
 5 files changed, 155 insertions(+), 3 deletions(-)

-- 
2.10.0.372.g6fe1b14

[PATCH v2 1/4] mfd: ti_am335x_tscadc: store physical address

[Mugunthan V N]

store the physical address of the device in its priv to use it
for DMA addressing in the client drivers.

Signed-off-by: Mugunthan V N <mugunthanvnm@ti.com>
---
 drivers/mfd/ti_am335x_tscadc.c       | 1 +
 include/linux/mfd/ti_am335x_tscadc.h | 1 +
 2 files changed, 2 insertions(+)

diff --git a/drivers/mfd/ti_am335x_tscadc.c b/drivers/mfd/ti_am335x_tscadc.c
index c8f027b..0f3fab4 100644
--- a/drivers/mfd/ti_am335x_tscadc.c
+++ b/drivers/mfd/ti_am335x_tscadc.c
@@ -183,6 +183,7 @@ static	int ti_tscadc_probe(struct platform_device *pdev)
 		tscadc->irq = err;
 
 	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+	tscadc->tscadc_phys_base = res->start;
 	tscadc->tscadc_base = devm_ioremap_resource(&pdev->dev, res);
 	if (IS_ERR(tscadc->tscadc_base))
 		return PTR_ERR(tscadc->tscadc_base);
diff --git a/include/linux/mfd/ti_am335x_tscadc.h b/include/linux/mfd/ti_am335x_tscadc.h
index 7f55b8b..e45a208 100644
--- a/include/linux/mfd/ti_am335x_tscadc.h
+++ b/include/linux/mfd/ti_am335x_tscadc.h
@@ -155,6 +155,7 @@ struct ti_tscadc_dev {
 	struct device *dev;
 	struct regmap *regmap;
 	void __iomem *tscadc_base;
+	phys_addr_t tscadc_phys_base;
 	int irq;
 	int used_cells;	/* 1-2 */
 	int tsc_wires;
-- 
2.10.0.372.g6fe1b14

[PATCH v2 2/4] drivers: iio: ti_am335x_adc: add dma support

[Mugunthan V N]

This patch adds the required pieces to ti_am335x_adc driver for
DMA support

Signed-off-by: Mugunthan V N <mugunthanvnm@ti.com>
---
 drivers/iio/adc/ti_am335x_adc.c      | 145 ++++++++++++++++++++++++++++++++++-
 include/linux/mfd/ti_am335x_tscadc.h |   7 ++
 2 files changed, 149 insertions(+), 3 deletions(-)

diff --git a/drivers/iio/adc/ti_am335x_adc.c b/drivers/iio/adc/ti_am335x_adc.c
index c3cfacca..7e250be 100644
--- a/drivers/iio/adc/ti_am335x_adc.c
+++ b/drivers/iio/adc/ti_am335x_adc.c
@@ -30,10 +30,28 @@
 #include <linux/iio/buffer.h>
 #include <linux/iio/kfifo_buf.h>
 
+#include <linux/dmaengine.h>
+#include <linux/dma-mapping.h>
+
+#define DMA_BUFFER_SIZE		SZ_2K
+
+struct tiadc_dma {
+	struct dma_slave_config	conf;
+	struct dma_chan		*chan;
+	dma_addr_t		addr;
+	dma_cookie_t		cookie;
+	u8			*buf;
+	int			current_period;
+	int			period_size;
+	u8			fifo_thresh;
+};
+
 struct tiadc_device {
 	struct ti_tscadc_dev *mfd_tscadc;
+	struct tiadc_dma dma;
 	struct mutex fifo1_lock; /* to protect fifo access */
 	int channels;
+	int total_ch_enabled;
 	u8 channel_line[8];
 	u8 channel_step[8];
 	int buffer_en_ch_steps;
@@ -198,6 +216,67 @@ static irqreturn_t tiadc_worker_h(int irq, void *private)
 	return IRQ_HANDLED;
 }
 
+static void tiadc_dma_rx_complete(void *param)
+{
+	struct iio_dev *indio_dev = param;
+	struct tiadc_device *adc_dev = iio_priv(indio_dev);
+	struct tiadc_dma *dma = &adc_dev->dma;
+	u8 *data;
+	int i;
+
+	data = dma->buf + dma->current_period * dma->period_size;
+	dma->current_period = 1 - dma->current_period; /* swap the buffer ID */
+
+	for (i = 0; i < dma->period_size; i += indio_dev->scan_bytes) {
+		iio_push_to_buffers(indio_dev, data);
+		data += indio_dev->scan_bytes;
+	}
+}
+
+static int tiadc_start_dma(struct iio_dev *indio_dev)
+{
+	struct tiadc_device *adc_dev = iio_priv(indio_dev);
+	struct tiadc_dma *dma = &adc_dev->dma;
+	struct dma_async_tx_descriptor *desc;
+
+	dma->current_period = 0; /* We start to fill period 0 */
+	/*
+	 * Make the fifo thresh as the multiple of total number of
+	 * channels enabled, so make sure that cyclic DMA period
+	 * length is also a multiple of total number of channels
+	 * enabled. This ensures that no invalid data is reported
+	 * to the stack via iio_push_to_buffers().
+	 */
+	dma->fifo_thresh = rounddown(FIFO1_THRESHOLD + 1,
+				     adc_dev->total_ch_enabled) - 1;
+	/* Make sure that period length is multiple of fifo thresh level */
+	dma->period_size = rounddown(DMA_BUFFER_SIZE / 2,
+				    (dma->fifo_thresh + 1) * sizeof(u16));
+
+	dma->conf.src_maxburst = dma->fifo_thresh + 1;
+	dmaengine_slave_config(dma->chan, &dma->conf);
+
+	desc = dmaengine_prep_dma_cyclic(dma->chan, dma->addr,
+					 dma->period_size * 2,
+					 dma->period_size, DMA_DEV_TO_MEM,
+					 DMA_PREP_INTERRUPT);
+	if (!desc)
+		return -EBUSY;
+
+	desc->callback = tiadc_dma_rx_complete;
+	desc->callback_param = indio_dev;
+
+	dma->cookie = dmaengine_submit(desc);
+
+	dma_async_issue_pending(dma->chan);
+
+	tiadc_writel(adc_dev, REG_FIFO1THR, dma->fifo_thresh);
+	tiadc_writel(adc_dev, REG_DMA1REQ, dma->fifo_thresh);
+	tiadc_writel(adc_dev, REG_DMAENABLE_SET, DMA_FIFO1);
+
+	return 0;
+}
+
 static int tiadc_buffer_preenable(struct iio_dev *indio_dev)
 {
 	struct tiadc_device *adc_dev = iio_priv(indio_dev);
@@ -218,20 +297,30 @@ static int tiadc_buffer_preenable(struct iio_dev *indio_dev)
 static int tiadc_buffer_postenable(struct iio_dev *indio_dev)
 {
 	struct tiadc_device *adc_dev = iio_priv(indio_dev);
+	struct tiadc_dma *dma = &adc_dev->dma;
+	unsigned int irq_enable;
 	unsigned int enb = 0;
 	u8 bit;
 
 	tiadc_step_config(indio_dev);
-	for_each_set_bit(bit, indio_dev->active_scan_mask, adc_dev->channels)
+	for_each_set_bit(bit, indio_dev->active_scan_mask, adc_dev->channels) {
 		enb |= (get_adc_step_bit(adc_dev, bit) << 1);
+		adc_dev->total_ch_enabled++;
+	}
 	adc_dev->buffer_en_ch_steps = enb;
 
+	if (dma->chan)
+		tiadc_start_dma(indio_dev);
+
 	am335x_tsc_se_set_cache(adc_dev->mfd_tscadc, enb);
 
 	tiadc_writel(adc_dev,  REG_IRQSTATUS, IRQENB_FIFO1THRES
 				| IRQENB_FIFO1OVRRUN | IRQENB_FIFO1UNDRFLW);
-	tiadc_writel(adc_dev,  REG_IRQENABLE, IRQENB_FIFO1THRES
-				| IRQENB_FIFO1OVRRUN);
+
+	irq_enable = IRQENB_FIFO1OVRRUN;
+	if (!dma->chan)
+		irq_enable |= IRQENB_FIFO1THRES;
+	tiadc_writel(adc_dev,  REG_IRQENABLE, irq_enable);
 
 	return 0;
 }
@@ -239,12 +328,18 @@ static int tiadc_buffer_postenable(struct iio_dev *indio_dev)
 static int tiadc_buffer_predisable(struct iio_dev *indio_dev)
 {
 	struct tiadc_device *adc_dev = iio_priv(indio_dev);
+	struct tiadc_dma *dma = &adc_dev->dma;
 	int fifo1count, i, read;
 
 	tiadc_writel(adc_dev, REG_IRQCLR, (IRQENB_FIFO1THRES |
 				IRQENB_FIFO1OVRRUN | IRQENB_FIFO1UNDRFLW));
 	am335x_tsc_se_clr(adc_dev->mfd_tscadc, adc_dev->buffer_en_ch_steps);
 	adc_dev->buffer_en_ch_steps = 0;
+	adc_dev->total_ch_enabled = 0;
+	if (dma->chan) {
+		tiadc_writel(adc_dev, REG_DMAENABLE_CLEAR, 0x2);
+		dmaengine_terminate_async(dma->chan);
+	}
 
 	/* Flush FIFO of leftover data in the time it takes to disable adc */
 	fifo1count = tiadc_readl(adc_dev, REG_FIFO1CNT);
@@ -430,6 +525,38 @@ static const struct iio_info tiadc_info = {
 	.driver_module = THIS_MODULE,
 };
 
+static int tiadc_request_dma(struct platform_device *pdev,
+			     struct tiadc_device *adc_dev)
+{
+	struct tiadc_dma	*dma = &adc_dev->dma;
+	dma_cap_mask_t		mask;
+
+	/* Default slave configuration parameters */
+	dma->conf.direction = DMA_DEV_TO_MEM;
+	dma->conf.src_addr_width = DMA_SLAVE_BUSWIDTH_2_BYTES;
+	dma->conf.src_addr = adc_dev->mfd_tscadc->tscadc_phys_base + REG_FIFO1;
+
+	dma_cap_zero(mask);
+	dma_cap_set(DMA_CYCLIC, mask);
+
+	/* Get a channel for RX */
+	dma->chan = dma_request_chan(adc_dev->mfd_tscadc->dev, "fifo1");
+	if (!dma->chan)
+		return -ENODEV;
+
+	/* RX buffer */
+	dma->buf = dma_alloc_coherent(dma->chan->device->dev, DMA_BUFFER_SIZE,
+				      &dma->addr, GFP_KERNEL);
+	if (!dma->buf)
+		goto err;
+
+	return 0;
+err:
+	dma_release_channel(dma->chan);
+
+	return -ENOMEM;
+}
+
 static int tiadc_parse_dt(struct platform_device *pdev,
 			  struct tiadc_device *adc_dev)
 {
@@ -512,8 +639,14 @@ static int tiadc_probe(struct platform_device *pdev)
 
 	platform_set_drvdata(pdev, indio_dev);
 
+	err = tiadc_request_dma(pdev, adc_dev);
+	if (err && err != -ENODEV)
+		goto err_dma;
+
 	return 0;
 
+err_dma:
+	iio_device_unregister(indio_dev);
 err_buffer_unregister:
 	tiadc_iio_buffered_hardware_remove(indio_dev);
 err_free_channels:
@@ -525,8 +658,14 @@ static int tiadc_remove(struct platform_device *pdev)
 {
 	struct iio_dev *indio_dev = platform_get_drvdata(pdev);
 	struct tiadc_device *adc_dev = iio_priv(indio_dev);
+	struct tiadc_dma *dma = &adc_dev->dma;
 	u32 step_en;
 
+	if (dma->chan) {
+		dma_free_coherent(dma->chan->device->dev, DMA_BUFFER_SIZE,
+				  dma->buf, dma->addr);
+		dma_release_channel(dma->chan);
+	}
 	iio_device_unregister(indio_dev);
 	tiadc_iio_buffered_hardware_remove(indio_dev);
 	tiadc_channels_remove(indio_dev);
diff --git a/include/linux/mfd/ti_am335x_tscadc.h b/include/linux/mfd/ti_am335x_tscadc.h
index e45a208..b9a53e0 100644
--- a/include/linux/mfd/ti_am335x_tscadc.h
+++ b/include/linux/mfd/ti_am335x_tscadc.h
@@ -23,6 +23,8 @@
 #define REG_IRQENABLE		0x02C
 #define REG_IRQCLR		0x030
 #define REG_IRQWAKEUP		0x034
+#define REG_DMAENABLE_SET	0x038
+#define REG_DMAENABLE_CLEAR	0x03c
 #define REG_CTRL		0x040
 #define REG_ADCFSM		0x044
 #define REG_CLKDIV		0x04C
@@ -36,6 +38,7 @@
 #define REG_FIFO0THR		0xE8
 #define REG_FIFO1CNT		0xF0
 #define REG_FIFO1THR		0xF4
+#define REG_DMA1REQ		0xF8
 #define REG_FIFO0		0x100
 #define REG_FIFO1		0x200
 
@@ -126,6 +129,10 @@
 #define FIFOREAD_DATA_MASK (0xfff << 0)
 #define FIFOREAD_CHNLID_MASK (0xf << 16)
 
+/* DMA ENABLE/CLEAR Register */
+#define DMA_FIFO0		BIT(0)
+#define DMA_FIFO1		BIT(1)
+
 /* Sequencer Status */
 #define SEQ_STATUS BIT(5)
 #define CHARGE_STEP		0x11
-- 
2.10.0.372.g6fe1b14

[PATCH v2 3/4] ARM: dts: am33xx: add DMA properties for tscadc

[Mugunthan V N]

Add DMA properties for tscadc

Signed-off-by: Mugunthan V N <mugunthanvnm@ti.com>
---
 arch/arm/boot/dts/am33xx.dtsi | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/arch/arm/boot/dts/am33xx.dtsi b/arch/arm/boot/dts/am33xx.dtsi
index 98748c6..6d607b8 100644
--- a/arch/arm/boot/dts/am33xx.dtsi
+++ b/arch/arm/boot/dts/am33xx.dtsi
@@ -917,6 +917,8 @@
 			interrupts = <16>;
 			ti,hwmods = "adc_tsc";
 			status = "disabled";
+			dmas = <&edma 53 0>, <&edma 57 0>;
+			dma-names = "fifo0", "fifo1";
 
 			tsc {
 				compatible = "ti,am3359-tsc";
-- 
2.10.0.372.g6fe1b14

[PATCH v2 4/4] ARM: dts: am4372: add DMA properties for tscadc

[Mugunthan V N]

Add DMA properties for tscadc

Signed-off-by: Mugunthan V N <mugunthanvnm@ti.com>
---
 arch/arm/boot/dts/am4372.dtsi | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/arch/arm/boot/dts/am4372.dtsi b/arch/arm/boot/dts/am4372.dtsi
index 0fadae5..6094d17 100644
--- a/arch/arm/boot/dts/am4372.dtsi
+++ b/arch/arm/boot/dts/am4372.dtsi
@@ -867,6 +867,8 @@
 			clocks = <&adc_tsc_fck>;
 			clock-names = "fck";
 			status = "disabled";
+			dmas = <&edma 53 0>, <&edma 57 0>;
+			dma-names = "fifo0", "fifo1";
 
 			tsc {
 				compatible = "ti,am3359-tsc";
-- 
2.10.0.372.g6fe1b14

Re: [PATCH v2 2/4] drivers: iio: ti_am335x_adc: add dma support

[Peter Ujfalusi]

On 10/03/16 16:03, Mugunthan V N wrote:
> +static int tiadc_request_dma(struct platform_device *pdev,
> +			     struct tiadc_device *adc_dev)
> +{
> +	struct tiadc_dma	*dma = &adc_dev->dma;
> +	dma_cap_mask_t		mask;
> +
> +	/* Default slave configuration parameters */
> +	dma->conf.direction = DMA_DEV_TO_MEM;
> +	dma->conf.src_addr_width = DMA_SLAVE_BUSWIDTH_2_BYTES;
> +	dma->conf.src_addr = adc_dev->mfd_tscadc->tscadc_phys_base + REG_FIFO1;
> +
> +	dma_cap_zero(mask);
> +	dma_cap_set(DMA_CYCLIC, mask);
> +
> +	/* Get a channel for RX */
> +	dma->chan = dma_request_chan(adc_dev->mfd_tscadc->dev, "fifo1");
> +	if (!dma->chan)
> +		return -ENODEV;

dma_request_chan() ERR_PTR in case of failure, never NULL. You should reuse
the returned error code to support deferred probing.

> +
> +	/* RX buffer */
> +	dma->buf = dma_alloc_coherent(dma->chan->device->dev, DMA_BUFFER_SIZE,
> +				      &dma->addr, GFP_KERNEL);
> +	if (!dma->buf)
> +		goto err;
> +
> +	return 0;
> +err:
> +	dma_release_channel(dma->chan);
> +
> +	return -ENOMEM;
> +}
> +
>  static int tiadc_parse_dt(struct platform_device *pdev,
>  			  struct tiadc_device *adc_dev)
>  {
> @@ -512,8 +639,14 @@ static int tiadc_probe(struct platform_device *pdev)
>  
>  	platform_set_drvdata(pdev, indio_dev);
>  
> +	err = tiadc_request_dma(pdev, adc_dev);
> +	if (err && err != -ENODEV)
> +		goto err_dma;

You should handle the deferred probing for DMA channel.

> +
>  	return 0;
>  
> +err_dma:
> +	iio_device_unregister(indio_dev);
>  err_buffer_unregister:
>  	tiadc_iio_buffered_hardware_remove(indio_dev);
>  err_free_channels:
> @@ -525,8 +658,14 @@ static int tiadc_remove(struct platform_device *pdev)
>  {
>  	struct iio_dev *indio_dev = platform_get_drvdata(pdev);
>  	struct tiadc_device *adc_dev = iio_priv(indio_dev);
> +	struct tiadc_dma *dma = &adc_dev->dma;
>  	u32 step_en;
>  
> +	if (dma->chan) {
> +		dma_free_coherent(dma->chan->device->dev, DMA_BUFFER_SIZE,
> +				  dma->buf, dma->addr);
> +		dma_release_channel(dma->chan);
> +	}
>  	iio_device_unregister(indio_dev);
>  	tiadc_iio_buffered_hardware_remove(indio_dev);
>  	tiadc_channels_remove(indio_dev);
> diff --git a/include/linux/mfd/ti_am335x_tscadc.h b/include/linux/mfd/ti_am335x_tscadc.h
> index e45a208..b9a53e0 100644
> --- a/include/linux/mfd/ti_am335x_tscadc.h
> +++ b/include/linux/mfd/ti_am335x_tscadc.h
> @@ -23,6 +23,8 @@
>  #define REG_IRQENABLE		0x02C
>  #define REG_IRQCLR		0x030
>  #define REG_IRQWAKEUP		0x034
> +#define REG_DMAENABLE_SET	0x038
> +#define REG_DMAENABLE_CLEAR	0x03c
>  #define REG_CTRL		0x040
>  #define REG_ADCFSM		0x044
>  #define REG_CLKDIV		0x04C
> @@ -36,6 +38,7 @@
>  #define REG_FIFO0THR		0xE8
>  #define REG_FIFO1CNT		0xF0
>  #define REG_FIFO1THR		0xF4
> +#define REG_DMA1REQ		0xF8
>  #define REG_FIFO0		0x100
>  #define REG_FIFO1		0x200
>  
> @@ -126,6 +129,10 @@
>  #define FIFOREAD_DATA_MASK (0xfff << 0)
>  #define FIFOREAD_CHNLID_MASK (0xf << 16)
>  
> +/* DMA ENABLE/CLEAR Register */
> +#define DMA_FIFO0		BIT(0)
> +#define DMA_FIFO1		BIT(1)
> +
>  /* Sequencer Status */
>  #define SEQ_STATUS BIT(5)
>  #define CHARGE_STEP		0x11
> 


-- 
Péter

Re: [PATCH v2 2/4] drivers: iio: ti_am335x_adc: add dma support

[Mugunthan V N]

On Tuesday 04 October 2016 02:02 PM, Peter Ujfalusi wrote:
> On 10/03/16 16:03, Mugunthan V N wrote:
>> +static int tiadc_request_dma(struct platform_device *pdev,
>> +			     struct tiadc_device *adc_dev)
>> +{
>> +	struct tiadc_dma	*dma = &adc_dev->dma;
>> +	dma_cap_mask_t		mask;
>> +
>> +	/* Default slave configuration parameters */
>> +	dma->conf.direction = DMA_DEV_TO_MEM;
>> +	dma->conf.src_addr_width = DMA_SLAVE_BUSWIDTH_2_BYTES;
>> +	dma->conf.src_addr = adc_dev->mfd_tscadc->tscadc_phys_base + REG_FIFO1;
>> +
>> +	dma_cap_zero(mask);
>> +	dma_cap_set(DMA_CYCLIC, mask);
>> +
>> +	/* Get a channel for RX */
>> +	dma->chan = dma_request_chan(adc_dev->mfd_tscadc->dev, "fifo1");
>> +	if (!dma->chan)
>> +		return -ENODEV;
> 
> dma_request_chan() ERR_PTR in case of failure, never NULL. You should reuse
> the returned error code to support deferred probing.

Will fix this in v3.

> 
>> +
>> +	/* RX buffer */
>> +	dma->buf = dma_alloc_coherent(dma->chan->device->dev, DMA_BUFFER_SIZE,
>> +				      &dma->addr, GFP_KERNEL);
>> +	if (!dma->buf)
>> +		goto err;
>> +
>> +	return 0;
>> +err:
>> +	dma_release_channel(dma->chan);
>> +
>> +	return -ENOMEM;
>> +}
>> +
>>  static int tiadc_parse_dt(struct platform_device *pdev,
>>  			  struct tiadc_device *adc_dev)
>>  {
>> @@ -512,8 +639,14 @@ static int tiadc_probe(struct platform_device *pdev)
>>  
>>  	platform_set_drvdata(pdev, indio_dev);
>>  
>> +	err = tiadc_request_dma(pdev, adc_dev);
>> +	if (err && err != -ENODEV)
>> +		goto err_dma;
> 
> You should handle the deferred probing for DMA channel.

+	dma->chan = dma_request_chan(adc_dev->mfd_tscadc->dev, "fifo1");
+	if (IS_ERR(dma->chan)) {
+		int ret = PTR_ERR(dma->chan);
+
+		dma->chan = NULL;
+		return ret;
+	}

With this probe defer will be taken care and ADC will continue without
DMA when request channel returns -ENODEV.

Regards
Mugunthan V N

> 
>> +
>>  	return 0;
>>  
>> +err_dma:
>> +	iio_device_unregister(indio_dev);
>>  err_buffer_unregister:
>>  	tiadc_iio_buffered_hardware_remove(indio_dev);
>>  err_free_channels:
>> @@ -525,8 +658,14 @@ static int tiadc_remove(struct platform_device *pdev)
>>  {
>>  	struct iio_dev *indio_dev = platform_get_drvdata(pdev);
>>  	struct tiadc_device *adc_dev = iio_priv(indio_dev);
>> +	struct tiadc_dma *dma = &adc_dev->dma;
>>  	u32 step_en;
>>  
>> +	if (dma->chan) {
>> +		dma_free_coherent(dma->chan->device->dev, DMA_BUFFER_SIZE,
>> +				  dma->buf, dma->addr);
>> +		dma_release_channel(dma->chan);
>> +	}
>>  	iio_device_unregister(indio_dev);
>>  	tiadc_iio_buffered_hardware_remove(indio_dev);
>>  	tiadc_channels_remove(indio_dev);
>> diff --git a/include/linux/mfd/ti_am335x_tscadc.h b/include/linux/mfd/ti_am335x_tscadc.h
>> index e45a208..b9a53e0 100644
>> --- a/include/linux/mfd/ti_am335x_tscadc.h
>> +++ b/include/linux/mfd/ti_am335x_tscadc.h
>> @@ -23,6 +23,8 @@
>>  #define REG_IRQENABLE		0x02C
>>  #define REG_IRQCLR		0x030
>>  #define REG_IRQWAKEUP		0x034
>> +#define REG_DMAENABLE_SET	0x038
>> +#define REG_DMAENABLE_CLEAR	0x03c
>>  #define REG_CTRL		0x040
>>  #define REG_ADCFSM		0x044
>>  #define REG_CLKDIV		0x04C
>> @@ -36,6 +38,7 @@
>>  #define REG_FIFO0THR		0xE8
>>  #define REG_FIFO1CNT		0xF0
>>  #define REG_FIFO1THR		0xF4
>> +#define REG_DMA1REQ		0xF8
>>  #define REG_FIFO0		0x100
>>  #define REG_FIFO1		0x200
>>  
>> @@ -126,6 +129,10 @@
>>  #define FIFOREAD_DATA_MASK (0xfff << 0)
>>  #define FIFOREAD_CHNLID_MASK (0xf << 16)
>>  
>> +/* DMA ENABLE/CLEAR Register */
>> +#define DMA_FIFO0		BIT(0)
>> +#define DMA_FIFO1		BIT(1)
>> +
>>  /* Sequencer Status */
>>  #define SEQ_STATUS BIT(5)
>>  #define CHARGE_STEP		0x11
>>
> 
> 

Re: [PATCH v2 2/4] drivers: iio: ti_am335x_adc: add dma support

[Peter Ujfalusi]

On 10/05/16 09:21, Mugunthan V N wrote:
> On Tuesday 04 October 2016 02:02 PM, Peter Ujfalusi wrote:
>> On 10/03/16 16:03, Mugunthan V N wrote:
>>> +static int tiadc_request_dma(struct platform_device *pdev,
>>> +			     struct tiadc_device *adc_dev)
>>> +{
>>> +	struct tiadc_dma	*dma = &adc_dev->dma;
>>> +	dma_cap_mask_t		mask;
>>> +
>>> +	/* Default slave configuration parameters */
>>> +	dma->conf.direction = DMA_DEV_TO_MEM;
>>> +	dma->conf.src_addr_width = DMA_SLAVE_BUSWIDTH_2_BYTES;
>>> +	dma->conf.src_addr = adc_dev->mfd_tscadc->tscadc_phys_base + REG_FIFO1;
>>> +
>>> +	dma_cap_zero(mask);
>>> +	dma_cap_set(DMA_CYCLIC, mask);
>>> +
>>> +	/* Get a channel for RX */
>>> +	dma->chan = dma_request_chan(adc_dev->mfd_tscadc->dev, "fifo1");
>>> +	if (!dma->chan)
>>> +		return -ENODEV;
>>
>> dma_request_chan() ERR_PTR in case of failure, never NULL. You should reuse
>> the returned error code to support deferred probing.
> 
> Will fix this in v3.
> 
>>
>>> +
>>> +	/* RX buffer */
>>> +	dma->buf = dma_alloc_coherent(dma->chan->device->dev, DMA_BUFFER_SIZE,
>>> +				      &dma->addr, GFP_KERNEL);
>>> +	if (!dma->buf)
>>> +		goto err;
>>> +
>>> +	return 0;
>>> +err:
>>> +	dma_release_channel(dma->chan);
>>> +
>>> +	return -ENOMEM;
>>> +}
>>> +
>>>  static int tiadc_parse_dt(struct platform_device *pdev,
>>>  			  struct tiadc_device *adc_dev)
>>>  {
>>> @@ -512,8 +639,14 @@ static int tiadc_probe(struct platform_device *pdev)
>>>  
>>>  	platform_set_drvdata(pdev, indio_dev);
>>>  
>>> +	err = tiadc_request_dma(pdev, adc_dev);
>>> +	if (err && err != -ENODEV)
>>> +		goto err_dma;
>>
>> You should handle the deferred probing for DMA channel.
> 
> +	dma->chan = dma_request_chan(adc_dev->mfd_tscadc->dev, "fifo1");
> +	if (IS_ERR(dma->chan)) {
> +		int ret = PTR_ERR(dma->chan);
> +
> +		dma->chan = NULL;
> +		return ret;

You don't need the 'ret' variable:
		return PTR_ERR(dma->chan);

> +	}
> 
> With this probe defer will be taken care and ADC will continue without
> DMA when request channel returns -ENODEV.

I would rather have explicit check for deferred probe:

err = tiadc_request_dma(pdev, adc_dev);
if (err && err == -EPROBE_DEFER)
	goto err_dma;


-- 
Péter

Re: [PATCH v2 2/4] drivers: iio: ti_am335x_adc: add dma support

[Mugunthan V N]

On Wednesday 05 October 2016 12:01 PM, Peter Ujfalusi wrote:
> On 10/05/16 09:21, Mugunthan V N wrote:
>> On Tuesday 04 October 2016 02:02 PM, Peter Ujfalusi wrote:
>>> On 10/03/16 16:03, Mugunthan V N wrote:
>>>> +static int tiadc_request_dma(struct platform_device *pdev,
>>>> +			     struct tiadc_device *adc_dev)
>>>> +{
>>>> +	struct tiadc_dma	*dma = &adc_dev->dma;
>>>> +	dma_cap_mask_t		mask;
>>>> +
>>>> +	/* Default slave configuration parameters */
>>>> +	dma->conf.direction = DMA_DEV_TO_MEM;
>>>> +	dma->conf.src_addr_width = DMA_SLAVE_BUSWIDTH_2_BYTES;
>>>> +	dma->conf.src_addr = adc_dev->mfd_tscadc->tscadc_phys_base + REG_FIFO1;
>>>> +
>>>> +	dma_cap_zero(mask);
>>>> +	dma_cap_set(DMA_CYCLIC, mask);
>>>> +
>>>> +	/* Get a channel for RX */
>>>> +	dma->chan = dma_request_chan(adc_dev->mfd_tscadc->dev, "fifo1");
>>>> +	if (!dma->chan)
>>>> +		return -ENODEV;
>>>
>>> dma_request_chan() ERR_PTR in case of failure, never NULL. You should reuse
>>> the returned error code to support deferred probing.
>>
>> Will fix this in v3.
>>
>>>
>>>> +
>>>> +	/* RX buffer */
>>>> +	dma->buf = dma_alloc_coherent(dma->chan->device->dev, DMA_BUFFER_SIZE,
>>>> +				      &dma->addr, GFP_KERNEL);
>>>> +	if (!dma->buf)
>>>> +		goto err;
>>>> +
>>>> +	return 0;
>>>> +err:
>>>> +	dma_release_channel(dma->chan);
>>>> +
>>>> +	return -ENOMEM;
>>>> +}
>>>> +
>>>>  static int tiadc_parse_dt(struct platform_device *pdev,
>>>>  			  struct tiadc_device *adc_dev)
>>>>  {
>>>> @@ -512,8 +639,14 @@ static int tiadc_probe(struct platform_device *pdev)
>>>>  
>>>>  	platform_set_drvdata(pdev, indio_dev);
>>>>  
>>>> +	err = tiadc_request_dma(pdev, adc_dev);
>>>> +	if (err && err != -ENODEV)
>>>> +		goto err_dma;
>>>
>>> You should handle the deferred probing for DMA channel.
>>
>> +	dma->chan = dma_request_chan(adc_dev->mfd_tscadc->dev, "fifo1");
>> +	if (IS_ERR(dma->chan)) {
>> +		int ret = PTR_ERR(dma->chan);
>> +
>> +		dma->chan = NULL;
>> +		return ret;
> 
> You don't need the 'ret' variable:
> 		return PTR_ERR(dma->chan);

So you mean change all *if (dma->chan)* to *if (IS_ERR(dma->chan))*?

> 
>> +	}
>>
>> With this probe defer will be taken care and ADC will continue without
>> DMA when request channel returns -ENODEV.
> 
> I would rather have explicit check for deferred probe:
> 
> err = tiadc_request_dma(pdev, adc_dev);
> if (err && err == -EPROBE_DEFER)
> 	goto err_dma;

But in this case any other failure other than -EPROBE_DEFER will be
masked and ADC will be in PIO mode?

Regards
Mugunthan V N

Re: [PATCH v2 2/4] drivers: iio: ti_am335x_adc: add dma support

[Peter Ujfalusi]

On 10/05/16 11:17, Mugunthan V N wrote:
> On Wednesday 05 October 2016 12:01 PM, Peter Ujfalusi wrote:
>> On 10/05/16 09:21, Mugunthan V N wrote:
>>> On Tuesday 04 October 2016 02:02 PM, Peter Ujfalusi wrote:
>>>> On 10/03/16 16:03, Mugunthan V N wrote:
>>>>> +static int tiadc_request_dma(struct platform_device *pdev,
>>>>> +			     struct tiadc_device *adc_dev)
>>>>> +{
>>>>> +	struct tiadc_dma	*dma = &adc_dev->dma;
>>>>> +	dma_cap_mask_t		mask;
>>>>> +
>>>>> +	/* Default slave configuration parameters */
>>>>> +	dma->conf.direction = DMA_DEV_TO_MEM;
>>>>> +	dma->conf.src_addr_width = DMA_SLAVE_BUSWIDTH_2_BYTES;
>>>>> +	dma->conf.src_addr = adc_dev->mfd_tscadc->tscadc_phys_base + REG_FIFO1;
>>>>> +
>>>>> +	dma_cap_zero(mask);
>>>>> +	dma_cap_set(DMA_CYCLIC, mask);
>>>>> +
>>>>> +	/* Get a channel for RX */
>>>>> +	dma->chan = dma_request_chan(adc_dev->mfd_tscadc->dev, "fifo1");
>>>>> +	if (!dma->chan)
>>>>> +		return -ENODEV;
>>>>
>>>> dma_request_chan() ERR_PTR in case of failure, never NULL. You should reuse
>>>> the returned error code to support deferred probing.
>>>
>>> Will fix this in v3.
>>>
>>>>
>>>>> +
>>>>> +	/* RX buffer */
>>>>> +	dma->buf = dma_alloc_coherent(dma->chan->device->dev, DMA_BUFFER_SIZE,
>>>>> +				      &dma->addr, GFP_KERNEL);
>>>>> +	if (!dma->buf)
>>>>> +		goto err;
>>>>> +
>>>>> +	return 0;
>>>>> +err:
>>>>> +	dma_release_channel(dma->chan);
>>>>> +
>>>>> +	return -ENOMEM;
>>>>> +}
>>>>> +
>>>>>  static int tiadc_parse_dt(struct platform_device *pdev,
>>>>>  			  struct tiadc_device *adc_dev)
>>>>>  {
>>>>> @@ -512,8 +639,14 @@ static int tiadc_probe(struct platform_device *pdev)
>>>>>  
>>>>>  	platform_set_drvdata(pdev, indio_dev);
>>>>>  
>>>>> +	err = tiadc_request_dma(pdev, adc_dev);
>>>>> +	if (err && err != -ENODEV)
>>>>> +		goto err_dma;
>>>>
>>>> You should handle the deferred probing for DMA channel.
>>>
>>> +	dma->chan = dma_request_chan(adc_dev->mfd_tscadc->dev, "fifo1");
>>> +	if (IS_ERR(dma->chan)) {
>>> +		int ret = PTR_ERR(dma->chan);
>>> +
>>> +		dma->chan = NULL;
>>> +		return ret;
>>
>> You don't need the 'ret' variable:
>> 		return PTR_ERR(dma->chan);
> 
> So you mean change all *if (dma->chan)* to *if (IS_ERR(dma->chan))*?

Oh, sorry. Your version was fine as you NULL the dma->chan before the return.

> 
>>
>>> +	}
>>>
>>> With this probe defer will be taken care and ADC will continue without
>>> DMA when request channel returns -ENODEV.
>>
>> I would rather have explicit check for deferred probe:
>>
>> err = tiadc_request_dma(pdev, adc_dev);
>> if (err && err == -EPROBE_DEFER)
>> 	goto err_dma;
> 
> But in this case any other failure other than -EPROBE_DEFER will be
> masked and ADC will be in PIO mode?

Yes, exactly. If we fail to get the DMA channel we should not use the DMA and
we only want to handle the deferred probing.

> 
> Regards
> Mugunthan V N
> 


-- 
Péter

Re: [PATCH v2 2/4] drivers: iio: ti_am335x_adc: add dma support

[Mugunthan V N]

On Wednesday 05 October 2016 02:16 PM, Peter Ujfalusi wrote:
> On 10/05/16 11:17, Mugunthan V N wrote:
>> On Wednesday 05 October 2016 12:01 PM, Peter Ujfalusi wrote:
>>> On 10/05/16 09:21, Mugunthan V N wrote:
>>>> On Tuesday 04 October 2016 02:02 PM, Peter Ujfalusi wrote:
>>>>> On 10/03/16 16:03, Mugunthan V N wrote:
>>>>>> +static int tiadc_request_dma(struct platform_device *pdev,
>>>>>> +			     struct tiadc_device *adc_dev)
>>>>>> +{
>>>>>> +	struct tiadc_dma	*dma = &adc_dev->dma;
>>>>>> +	dma_cap_mask_t		mask;
>>>>>> +
>>>>>> +	/* Default slave configuration parameters */
>>>>>> +	dma->conf.direction = DMA_DEV_TO_MEM;
>>>>>> +	dma->conf.src_addr_width = DMA_SLAVE_BUSWIDTH_2_BYTES;
>>>>>> +	dma->conf.src_addr = adc_dev->mfd_tscadc->tscadc_phys_base + REG_FIFO1;
>>>>>> +
>>>>>> +	dma_cap_zero(mask);
>>>>>> +	dma_cap_set(DMA_CYCLIC, mask);
>>>>>> +
>>>>>> +	/* Get a channel for RX */
>>>>>> +	dma->chan = dma_request_chan(adc_dev->mfd_tscadc->dev, "fifo1");
>>>>>> +	if (!dma->chan)
>>>>>> +		return -ENODEV;
>>>>>
>>>>> dma_request_chan() ERR_PTR in case of failure, never NULL. You should reuse
>>>>> the returned error code to support deferred probing.
>>>>
>>>> Will fix this in v3.
>>>>
>>>>>
>>>>>> +
>>>>>> +	/* RX buffer */
>>>>>> +	dma->buf = dma_alloc_coherent(dma->chan->device->dev, DMA_BUFFER_SIZE,
>>>>>> +				      &dma->addr, GFP_KERNEL);
>>>>>> +	if (!dma->buf)
>>>>>> +		goto err;
>>>>>> +
>>>>>> +	return 0;
>>>>>> +err:
>>>>>> +	dma_release_channel(dma->chan);
>>>>>> +
>>>>>> +	return -ENOMEM;
>>>>>> +}
>>>>>> +
>>>>>>  static int tiadc_parse_dt(struct platform_device *pdev,
>>>>>>  			  struct tiadc_device *adc_dev)
>>>>>>  {
>>>>>> @@ -512,8 +639,14 @@ static int tiadc_probe(struct platform_device *pdev)
>>>>>>  
>>>>>>  	platform_set_drvdata(pdev, indio_dev);
>>>>>>  
>>>>>> +	err = tiadc_request_dma(pdev, adc_dev);
>>>>>> +	if (err && err != -ENODEV)
>>>>>> +		goto err_dma;
>>>>>
>>>>> You should handle the deferred probing for DMA channel.
>>>>
>>>> +	dma->chan = dma_request_chan(adc_dev->mfd_tscadc->dev, "fifo1");
>>>> +	if (IS_ERR(dma->chan)) {
>>>> +		int ret = PTR_ERR(dma->chan);
>>>> +
>>>> +		dma->chan = NULL;
>>>> +		return ret;
>>>
>>> You don't need the 'ret' variable:
>>> 		return PTR_ERR(dma->chan);
>>
>> So you mean change all *if (dma->chan)* to *if (IS_ERR(dma->chan))*?
> 
> Oh, sorry. Your version was fine as you NULL the dma->chan before the return.
> 
>>
>>>
>>>> +	}
>>>>
>>>> With this probe defer will be taken care and ADC will continue without
>>>> DMA when request channel returns -ENODEV.
>>>
>>> I would rather have explicit check for deferred probe:
>>>
>>> err = tiadc_request_dma(pdev, adc_dev);
>>> if (err && err == -EPROBE_DEFER)
>>> 	goto err_dma;
>>
>> But in this case any other failure other than -EPROBE_DEFER will be
>> masked and ADC will be in PIO mode?
> 
> Yes, exactly. If we fail to get the DMA channel we should not use the DMA and
> we only want to handle the deferred probing.
> 

Okay, will update accordingly in next version.

Regards
Mugunthan V N