drivers/spi/spi-pxa2xx-dma.c - kernel/msm-4.9 - Gitiles

 /*
  * PXA2xx SPI DMA engine support.
  *
  * Copyright (C) 2013, Intel Corporation
  * Author: Mika Westerberg <mika.westerberg@linux.intel.com>
  *
  * 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.
  */

 #include <linux/device.h>
 #include <linux/dma-mapping.h>
 #include <linux/dmaengine.h>
 #include <linux/pxa2xx_ssp.h>
 #include <linux/scatterlist.h>
 #include <linux/sizes.h>
 #include <linux/spi/spi.h>
 #include <linux/spi/pxa2xx_spi.h>

 #include "spi-pxa2xx.h"

 static int pxa2xx_spi_map_dma_buffer(struct driver_data *drv_data,
 				     enum dma_data_direction dir)
 {
 	int i, nents, len = drv_data->len;
 	struct scatterlist *sg;
 	struct device *dmadev;
 	struct sg_table *sgt;
 	void *buf, *pbuf;

 	if (dir == DMA_TO_DEVICE) {
 		dmadev = drv_data->tx_chan->device->dev;
 		sgt = &drv_data->tx_sgt;
 		buf = drv_data->tx;
 		drv_data->tx_map_len = len;
 	} else {
 		dmadev = drv_data->rx_chan->device->dev;
 		sgt = &drv_data->rx_sgt;
 		buf = drv_data->rx;
 		drv_data->rx_map_len = len;
 	}

 	nents = DIV_ROUND_UP(len, SZ_2K);
 	if (nents != sgt->nents) {
 		int ret;

 		sg_free_table(sgt);
 		ret = sg_alloc_table(sgt, nents, GFP_ATOMIC);
 		if (ret)
 			return ret;
 	}

 	pbuf = buf;
 	for_each_sg(sgt->sgl, sg, sgt->nents, i) {
 		size_t bytes = min_t(size_t, len, SZ_2K);

 		if (buf)
 			sg_set_buf(sg, pbuf, bytes);
 		else
 			sg_set_buf(sg, drv_data->dummy, bytes);

 		pbuf += bytes;
 		len -= bytes;
 	}

 	nents = dma_map_sg(dmadev, sgt->sgl, sgt->nents, dir);
 	if (!nents)
 		return -ENOMEM;

 	return nents;
 }

 static void pxa2xx_spi_unmap_dma_buffer(struct driver_data *drv_data,
 					enum dma_data_direction dir)
 {
 	struct device *dmadev;
 	struct sg_table *sgt;

 	if (dir == DMA_TO_DEVICE) {
 		dmadev = drv_data->tx_chan->device->dev;
 		sgt = &drv_data->tx_sgt;
 	} else {
 		dmadev = drv_data->rx_chan->device->dev;
 		sgt = &drv_data->rx_sgt;
 	}

 	dma_unmap_sg(dmadev, sgt->sgl, sgt->nents, dir);
 }

 static void pxa2xx_spi_unmap_dma_buffers(struct driver_data *drv_data)
 {
 	if (!drv_data->dma_mapped)
 		return;

 	pxa2xx_spi_unmap_dma_buffer(drv_data, DMA_FROM_DEVICE);
 	pxa2xx_spi_unmap_dma_buffer(drv_data, DMA_TO_DEVICE);

 	drv_data->dma_mapped = 0;
 }

 static void pxa2xx_spi_dma_transfer_complete(struct driver_data *drv_data,
 					     bool error)
 {
 	struct spi_message *msg = drv_data->cur_msg;

 	/*
 	 * It is possible that one CPU is handling ROR interrupt and other
 	 * just gets DMA completion. Calling pump_transfers() twice for the
 	 * same transfer leads to problems thus we prevent concurrent calls
 	 * by using ->dma_running.
 	 */
 	if (atomic_dec_and_test(&drv_data->dma_running)) {
 		/*
 		 * If the other CPU is still handling the ROR interrupt we
 		 * might not know about the error yet. So we re-check the
 		 * ROR bit here before we clear the status register.
 		 */
 		if (!error) {
 			u32 status = pxa2xx_spi_read(drv_data, SSSR)
 				     & drv_data->mask_sr;
 			error = status & SSSR_ROR;
 		}

 		/* Clear status & disable interrupts */
 		pxa2xx_spi_write(drv_data, SSCR1,
 				 pxa2xx_spi_read(drv_data, SSCR1)
 				 & ~drv_data->dma_cr1);
 		write_SSSR_CS(drv_data, drv_data->clear_sr);
 		if (!pxa25x_ssp_comp(drv_data))
 			pxa2xx_spi_write(drv_data, SSTO, 0);

 		if (!error) {
 			pxa2xx_spi_unmap_dma_buffers(drv_data);

 			drv_data->tx += drv_data->tx_map_len;
 			drv_data->rx += drv_data->rx_map_len;

 			msg->actual_length += drv_data->len;
 			msg->state = pxa2xx_spi_next_transfer(drv_data);
 		} else {
 			/* In case we got an error we disable the SSP now */
 			pxa2xx_spi_write(drv_data, SSCR0,
 					 pxa2xx_spi_read(drv_data, SSCR0)
 					 & ~SSCR0_SSE);

 			msg->state = ERROR_STATE;
 		}

 		tasklet_schedule(&drv_data->pump_transfers);
 	}
 }

 static void pxa2xx_spi_dma_callback(void *data)
 {
 	pxa2xx_spi_dma_transfer_complete(data, false);
 }

 static struct dma_async_tx_descriptor *
 pxa2xx_spi_dma_prepare_one(struct driver_data *drv_data,
 			   enum dma_transfer_direction dir)
 {
 	struct chip_data *chip = drv_data->cur_chip;
 	enum dma_slave_buswidth width;
 	struct dma_slave_config cfg;
 	struct dma_chan *chan;
 	struct sg_table *sgt;
 	int nents, ret;

 	switch (drv_data->n_bytes) {
 	case 1:
 		width = DMA_SLAVE_BUSWIDTH_1_BYTE;
 		break;
 	case 2:
 		width = DMA_SLAVE_BUSWIDTH_2_BYTES;
 		break;
 	default:
 		width = DMA_SLAVE_BUSWIDTH_4_BYTES;
 		break;
 	}

 	memset(&cfg, 0, sizeof(cfg));
 	cfg.direction = dir;

 	if (dir == DMA_MEM_TO_DEV) {
 		cfg.dst_addr = drv_data->ssdr_physical;
 		cfg.dst_addr_width = width;
 		cfg.dst_maxburst = chip->dma_burst_size;

 		sgt = &drv_data->tx_sgt;
 		nents = drv_data->tx_nents;
 		chan = drv_data->tx_chan;
 	} else {
 		cfg.src_addr = drv_data->ssdr_physical;
 		cfg.src_addr_width = width;
 		cfg.src_maxburst = chip->dma_burst_size;

 		sgt = &drv_data->rx_sgt;
 		nents = drv_data->rx_nents;
 		chan = drv_data->rx_chan;
 	}

 	ret = dmaengine_slave_config(chan, &cfg);
 	if (ret) {
 		dev_warn(&drv_data->pdev->dev, "DMA slave config failed\n");
 		return NULL;
 	}

 	return dmaengine_prep_slave_sg(chan, sgt->sgl, nents, dir,
 				       DMA_PREP_INTERRUPT | DMA_CTRL_ACK);
 }

 bool pxa2xx_spi_dma_is_possible(size_t len)
 {
 	return len <= MAX_DMA_LEN;
 }

 int pxa2xx_spi_map_dma_buffers(struct driver_data *drv_data)
 {
 	const struct chip_data *chip = drv_data->cur_chip;
 	int ret;

 	if (!chip->enable_dma)
 		return 0;

 	/* Don't bother with DMA if we can't do even a single burst */
 	if (drv_data->len < chip->dma_burst_size)
 		return 0;

 	ret = pxa2xx_spi_map_dma_buffer(drv_data, DMA_TO_DEVICE);
 	if (ret <= 0) {
 		dev_warn(&drv_data->pdev->dev, "failed to DMA map TX\n");
 		return 0;
 	}

 	drv_data->tx_nents = ret;

 	ret = pxa2xx_spi_map_dma_buffer(drv_data, DMA_FROM_DEVICE);
 	if (ret <= 0) {
 		pxa2xx_spi_unmap_dma_buffer(drv_data, DMA_TO_DEVICE);
 		dev_warn(&drv_data->pdev->dev, "failed to DMA map RX\n");
 		return 0;
 	}

 	drv_data->rx_nents = ret;
 	return 1;
 }

 irqreturn_t pxa2xx_spi_dma_transfer(struct driver_data *drv_data)
 {
 	u32 status;

 	status = pxa2xx_spi_read(drv_data, SSSR) & drv_data->mask_sr;
 	if (status & SSSR_ROR) {
 		dev_err(&drv_data->pdev->dev, "FIFO overrun\n");

 		dmaengine_terminate_all(drv_data->rx_chan);
 		dmaengine_terminate_all(drv_data->tx_chan);

 		pxa2xx_spi_dma_transfer_complete(drv_data, true);
 		return IRQ_HANDLED;
 	}

 	return IRQ_NONE;
 }

 int pxa2xx_spi_dma_prepare(struct driver_data *drv_data, u32 dma_burst)
 {
 	struct dma_async_tx_descriptor *tx_desc, *rx_desc;

 	tx_desc = pxa2xx_spi_dma_prepare_one(drv_data, DMA_MEM_TO_DEV);
 	if (!tx_desc) {
 		dev_err(&drv_data->pdev->dev,
 			"failed to get DMA TX descriptor\n");
 		return -EBUSY;
 	}

 	rx_desc = pxa2xx_spi_dma_prepare_one(drv_data, DMA_DEV_TO_MEM);
 	if (!rx_desc) {
 		dev_err(&drv_data->pdev->dev,
 			"failed to get DMA RX descriptor\n");
 		return -EBUSY;
 	}

 	/* We are ready when RX completes */
 	rx_desc->callback = pxa2xx_spi_dma_callback;
 	rx_desc->callback_param = drv_data;

 	dmaengine_submit(rx_desc);
 	dmaengine_submit(tx_desc);
 	return 0;
 }

 void pxa2xx_spi_dma_start(struct driver_data *drv_data)
 {
 	dma_async_issue_pending(drv_data->rx_chan);
 	dma_async_issue_pending(drv_data->tx_chan);

 	atomic_set(&drv_data->dma_running, 1);
 }

 int pxa2xx_spi_dma_setup(struct driver_data *drv_data)
 {
 	struct pxa2xx_spi_master *pdata = drv_data->master_info;
 	struct device *dev = &drv_data->pdev->dev;
 	dma_cap_mask_t mask;

 	dma_cap_zero(mask);
 	dma_cap_set(DMA_SLAVE, mask);

 	drv_data->dummy = devm_kzalloc(dev, SZ_2K, GFP_KERNEL);
 	if (!drv_data->dummy)
 		return -ENOMEM;

 	drv_data->tx_chan = dma_request_slave_channel_compat(mask,
 				pdata->dma_filter, pdata->tx_param, dev, "tx");
 	if (!drv_data->tx_chan)
 		return -ENODEV;

 	drv_data->rx_chan = dma_request_slave_channel_compat(mask,
 				pdata->dma_filter, pdata->rx_param, dev, "rx");
 	if (!drv_data->rx_chan) {
 		dma_release_channel(drv_data->tx_chan);
 		drv_data->tx_chan = NULL;
 		return -ENODEV;
 	}

 	return 0;
 }

 void pxa2xx_spi_dma_release(struct driver_data *drv_data)
 {
 	if (drv_data->rx_chan) {
 		dmaengine_terminate_all(drv_data->rx_chan);
 		dma_release_channel(drv_data->rx_chan);
 		sg_free_table(&drv_data->rx_sgt);
 		drv_data->rx_chan = NULL;
 	}
 	if (drv_data->tx_chan) {
 		dmaengine_terminate_all(drv_data->tx_chan);
 		dma_release_channel(drv_data->tx_chan);
 		sg_free_table(&drv_data->tx_sgt);
 		drv_data->tx_chan = NULL;
 	}
 }

 void pxa2xx_spi_dma_resume(struct driver_data *drv_data)
 {
 }

 int pxa2xx_spi_set_dma_burst_and_threshold(struct chip_data *chip,
 					   struct spi_device *spi,
 					   u8 bits_per_word, u32 *burst_code,
 					   u32 *threshold)
 {
 	struct pxa2xx_spi_chip *chip_info = spi->controller_data;

 	/*
 	 * If the DMA burst size is given in chip_info we use that,
 	 * otherwise we use the default. Also we use the default FIFO
 	 * thresholds for now.
 	 */
 	*burst_code = chip_info ? chip_info->dma_burst_size : 1;
 	*threshold = SSCR1_RxTresh(RX_THRESH_DFLT)
 		   | SSCR1_TxTresh(TX_THRESH_DFLT);

 	return 0;
 }
	/*
	* PXA2xx SPI DMA engine support.
	*
	* Copyright (C) 2013, Intel Corporation
	* Author: Mika Westerberg <mika.westerberg@linux.intel.com>
	*
	* 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.
	*/

	#include <linux/device.h>
	#include <linux/dma-mapping.h>
	#include <linux/dmaengine.h>
	#include <linux/pxa2xx_ssp.h>
	#include <linux/scatterlist.h>
	#include <linux/sizes.h>
	#include <linux/spi/spi.h>
	#include <linux/spi/pxa2xx_spi.h>

	#include "spi-pxa2xx.h"

	static int pxa2xx_spi_map_dma_buffer(struct driver_data *drv_data,
	enum dma_data_direction dir)
	{
	int i, nents, len = drv_data->len;
	struct scatterlist *sg;
	struct device *dmadev;
	struct sg_table *sgt;
	void buf, pbuf;

	if (dir == DMA_TO_DEVICE) {
	dmadev = drv_data->tx_chan->device->dev;
	sgt = &drv_data->tx_sgt;
	buf = drv_data->tx;
	drv_data->tx_map_len = len;
	} else {
	dmadev = drv_data->rx_chan->device->dev;
	sgt = &drv_data->rx_sgt;
	buf = drv_data->rx;
	drv_data->rx_map_len = len;
	}

	nents = DIV_ROUND_UP(len, SZ_2K);
	if (nents != sgt->nents) {
	int ret;

	sg_free_table(sgt);
	ret = sg_alloc_table(sgt, nents, GFP_ATOMIC);
	if (ret)
	return ret;
	}

	pbuf = buf;
	for_each_sg(sgt->sgl, sg, sgt->nents, i) {
	size_t bytes = min_t(size_t, len, SZ_2K);

	if (buf)
	sg_set_buf(sg, pbuf, bytes);
	else
	sg_set_buf(sg, drv_data->dummy, bytes);

	pbuf += bytes;
	len -= bytes;
	}

	nents = dma_map_sg(dmadev, sgt->sgl, sgt->nents, dir);
	if (!nents)
	return -ENOMEM;

	return nents;
	}

	static void pxa2xx_spi_unmap_dma_buffer(struct driver_data *drv_data,
	enum dma_data_direction dir)
	{
	struct device *dmadev;
	struct sg_table *sgt;

	if (dir == DMA_TO_DEVICE) {
	dmadev = drv_data->tx_chan->device->dev;
	sgt = &drv_data->tx_sgt;
	} else {
	dmadev = drv_data->rx_chan->device->dev;
	sgt = &drv_data->rx_sgt;
	}

	dma_unmap_sg(dmadev, sgt->sgl, sgt->nents, dir);
	}

	static void pxa2xx_spi_unmap_dma_buffers(struct driver_data *drv_data)
	{
	if (!drv_data->dma_mapped)
	return;

	pxa2xx_spi_unmap_dma_buffer(drv_data, DMA_FROM_DEVICE);
	pxa2xx_spi_unmap_dma_buffer(drv_data, DMA_TO_DEVICE);

	drv_data->dma_mapped = 0;
	}

	static void pxa2xx_spi_dma_transfer_complete(struct driver_data *drv_data,
	bool error)
	{
	struct spi_message *msg = drv_data->cur_msg;

	/*
	* It is possible that one CPU is handling ROR interrupt and other
	* just gets DMA completion. Calling pump_transfers() twice for the
	* same transfer leads to problems thus we prevent concurrent calls
	* by using ->dma_running.
	*/
	if (atomic_dec_and_test(&drv_data->dma_running)) {
	/*
	* If the other CPU is still handling the ROR interrupt we
	* might not know about the error yet. So we re-check the
	* ROR bit here before we clear the status register.
	*/
	if (!error) {
	u32 status = pxa2xx_spi_read(drv_data, SSSR)
	& drv_data->mask_sr;
	error = status & SSSR_ROR;
	}

	/* Clear status & disable interrupts */
	pxa2xx_spi_write(drv_data, SSCR1,
	pxa2xx_spi_read(drv_data, SSCR1)
	& ~drv_data->dma_cr1);
	write_SSSR_CS(drv_data, drv_data->clear_sr);
	if (!pxa25x_ssp_comp(drv_data))
	pxa2xx_spi_write(drv_data, SSTO, 0);

	if (!error) {
	pxa2xx_spi_unmap_dma_buffers(drv_data);

	drv_data->tx += drv_data->tx_map_len;
	drv_data->rx += drv_data->rx_map_len;

	msg->actual_length += drv_data->len;
	msg->state = pxa2xx_spi_next_transfer(drv_data);
	} else {
	/* In case we got an error we disable the SSP now */
	pxa2xx_spi_write(drv_data, SSCR0,
	pxa2xx_spi_read(drv_data, SSCR0)
	& ~SSCR0_SSE);

	msg->state = ERROR_STATE;
	}

	tasklet_schedule(&drv_data->pump_transfers);
	}
	}

	static void pxa2xx_spi_dma_callback(void *data)
	{
	pxa2xx_spi_dma_transfer_complete(data, false);
	}

	static struct dma_async_tx_descriptor *
	pxa2xx_spi_dma_prepare_one(struct driver_data *drv_data,
	enum dma_transfer_direction dir)
	{
	struct chip_data *chip = drv_data->cur_chip;
	enum dma_slave_buswidth width;
	struct dma_slave_config cfg;
	struct dma_chan *chan;
	struct sg_table *sgt;
	int nents, ret;

	switch (drv_data->n_bytes) {
	case 1:
	width = DMA_SLAVE_BUSWIDTH_1_BYTE;
	break;
	case 2:
	width = DMA_SLAVE_BUSWIDTH_2_BYTES;
	break;
	default:
	width = DMA_SLAVE_BUSWIDTH_4_BYTES;
	break;
	}

	memset(&cfg, 0, sizeof(cfg));
	cfg.direction = dir;

	if (dir == DMA_MEM_TO_DEV) {
	cfg.dst_addr = drv_data->ssdr_physical;
	cfg.dst_addr_width = width;
	cfg.dst_maxburst = chip->dma_burst_size;

	sgt = &drv_data->tx_sgt;
	nents = drv_data->tx_nents;
	chan = drv_data->tx_chan;
	} else {
	cfg.src_addr = drv_data->ssdr_physical;
	cfg.src_addr_width = width;
	cfg.src_maxburst = chip->dma_burst_size;

	sgt = &drv_data->rx_sgt;
	nents = drv_data->rx_nents;
	chan = drv_data->rx_chan;
	}

	ret = dmaengine_slave_config(chan, &cfg);
	if (ret) {
	dev_warn(&drv_data->pdev->dev, "DMA slave config failed\n");
	return NULL;
	}

	return dmaengine_prep_slave_sg(chan, sgt->sgl, nents, dir,
	DMA_PREP_INTERRUPT \| DMA_CTRL_ACK);
	}

	bool pxa2xx_spi_dma_is_possible(size_t len)
	{
	return len <= MAX_DMA_LEN;
	}

	int pxa2xx_spi_map_dma_buffers(struct driver_data *drv_data)
	{
	const struct chip_data *chip = drv_data->cur_chip;
	int ret;

	if (!chip->enable_dma)
	return 0;

	/* Don't bother with DMA if we can't do even a single burst */
	if (drv_data->len < chip->dma_burst_size)
	return 0;

	ret = pxa2xx_spi_map_dma_buffer(drv_data, DMA_TO_DEVICE);
	if (ret <= 0) {
	dev_warn(&drv_data->pdev->dev, "failed to DMA map TX\n");
	return 0;
	}

	drv_data->tx_nents = ret;

	ret = pxa2xx_spi_map_dma_buffer(drv_data, DMA_FROM_DEVICE);
	if (ret <= 0) {
	pxa2xx_spi_unmap_dma_buffer(drv_data, DMA_TO_DEVICE);
	dev_warn(&drv_data->pdev->dev, "failed to DMA map RX\n");
	return 0;
	}

	drv_data->rx_nents = ret;
	return 1;
	}

	irqreturn_t pxa2xx_spi_dma_transfer(struct driver_data *drv_data)
	{
	u32 status;

	status = pxa2xx_spi_read(drv_data, SSSR) & drv_data->mask_sr;
	if (status & SSSR_ROR) {
	dev_err(&drv_data->pdev->dev, "FIFO overrun\n");

	dmaengine_terminate_all(drv_data->rx_chan);
	dmaengine_terminate_all(drv_data->tx_chan);

	pxa2xx_spi_dma_transfer_complete(drv_data, true);
	return IRQ_HANDLED;
	}

	return IRQ_NONE;
	}

	int pxa2xx_spi_dma_prepare(struct driver_data *drv_data, u32 dma_burst)
	{
	struct dma_async_tx_descriptor tx_desc, rx_desc;

	tx_desc = pxa2xx_spi_dma_prepare_one(drv_data, DMA_MEM_TO_DEV);
	if (!tx_desc) {
	dev_err(&drv_data->pdev->dev,
	"failed to get DMA TX descriptor\n");
	return -EBUSY;
	}

	rx_desc = pxa2xx_spi_dma_prepare_one(drv_data, DMA_DEV_TO_MEM);
	if (!rx_desc) {
	dev_err(&drv_data->pdev->dev,
	"failed to get DMA RX descriptor\n");
	return -EBUSY;
	}

	/* We are ready when RX completes */
	rx_desc->callback = pxa2xx_spi_dma_callback;
	rx_desc->callback_param = drv_data;

	dmaengine_submit(rx_desc);
	dmaengine_submit(tx_desc);
	return 0;
	}

	void pxa2xx_spi_dma_start(struct driver_data *drv_data)
	{
	dma_async_issue_pending(drv_data->rx_chan);
	dma_async_issue_pending(drv_data->tx_chan);

	atomic_set(&drv_data->dma_running, 1);
	}

	int pxa2xx_spi_dma_setup(struct driver_data *drv_data)
	{
	struct pxa2xx_spi_master *pdata = drv_data->master_info;
	struct device *dev = &drv_data->pdev->dev;
	dma_cap_mask_t mask;

	dma_cap_zero(mask);
	dma_cap_set(DMA_SLAVE, mask);

	drv_data->dummy = devm_kzalloc(dev, SZ_2K, GFP_KERNEL);
	if (!drv_data->dummy)
	return -ENOMEM;

	drv_data->tx_chan = dma_request_slave_channel_compat(mask,
	pdata->dma_filter, pdata->tx_param, dev, "tx");
	if (!drv_data->tx_chan)
	return -ENODEV;

	drv_data->rx_chan = dma_request_slave_channel_compat(mask,
	pdata->dma_filter, pdata->rx_param, dev, "rx");
	if (!drv_data->rx_chan) {
	dma_release_channel(drv_data->tx_chan);
	drv_data->tx_chan = NULL;
	return -ENODEV;
	}

	return 0;
	}

	void pxa2xx_spi_dma_release(struct driver_data *drv_data)
	{
	if (drv_data->rx_chan) {
	dmaengine_terminate_all(drv_data->rx_chan);
	dma_release_channel(drv_data->rx_chan);
	sg_free_table(&drv_data->rx_sgt);
	drv_data->rx_chan = NULL;
	}
	if (drv_data->tx_chan) {
	dmaengine_terminate_all(drv_data->tx_chan);
	dma_release_channel(drv_data->tx_chan);
	sg_free_table(&drv_data->tx_sgt);
	drv_data->tx_chan = NULL;
	}
	}

	void pxa2xx_spi_dma_resume(struct driver_data *drv_data)
	{
	}

	int pxa2xx_spi_set_dma_burst_and_threshold(struct chip_data *chip,
	struct spi_device *spi,
	u8 bits_per_word, u32 *burst_code,
	u32 *threshold)
	{
	struct pxa2xx_spi_chip *chip_info = spi->controller_data;

	/*
	* If the DMA burst size is given in chip_info we use that,
	* otherwise we use the default. Also we use the default FIFO
	* thresholds for now.
	*/
	*burst_code = chip_info ? chip_info->dma_burst_size : 1;
	*threshold = SSCR1_RxTresh(RX_THRESH_DFLT)
	\| SSCR1_TxTresh(TX_THRESH_DFLT);

	return 0;
	}