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Commit f438b9da authored by Mugunthan V N's avatar Mugunthan V N Committed by Jonathan Cameron
Browse files

drivers: iio: ti_am335x_adc: add dma support 



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

Signed-off-by: default avatarMugunthan V N <mugunthanvnm@ti.com>
Reviewed-by: default avatarPeter Ujfalusi <peter.ujfalusi@ti.com>
Signed-off-by: default avatarJonathan Cameron <jic23@kernel.org>
parent c9329d86

drivers/iio/adc/ti_am335x_adc.c

+145 −3
Original line number Diff line number Diff line
@@ -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 +525,41 @@ 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 (IS_ERR(dma->chan)) {

		int ret = PTR_ERR(dma->chan);



		dma->chan = NULL;

		return ret;

	}



	/* 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 +642,14 @@ static int tiadc_probe(struct platform_device *pdev) 


	platform_set_drvdata(pdev, indio_dev);



	err = tiadc_request_dma(pdev, adc_dev);

	if (err && err == -EPROBE_DEFER)

		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 +661,14 @@ 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);

include/linux/mfd/ti_am335x_tscadc.h

+7 −0
Original line number Diff line number Diff line
@@ -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