On Tuesday 04 October 2016 02:02 PM, Peter Ujfalusi wrote:

On 10/03/16 16:03, Mugunthan V N wrote:

quoted

+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.

quoted

+
+	/* 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

quoted

+
 	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