Re: [PATCH 10/12] spi: omap2-mcspi: add DMA engine support

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On Mon, 23 Apr 2012 17:07:32 +0100, Russell King <rmk+kernel@xxxxxxxxxxxxxxxx> wrote:
> Add DMA engine support to the OMAP SPI driver.  This supplements the
> private DMA API implementation contained within this driver, and the
> driver can be independently switched at build time between using DMA
> engine and the private DMA API for the transmit and receive sides.
> 
> Tested-by: Shubhrajyoti <shubhrajyoti@xxxxxx>
> Signed-off-by: Russell King <rmk+kernel@xxxxxxxxxxxxxxxx>
> ---
>  drivers/spi/spi-omap2-mcspi.c |  184 ++++++++++++++++++++++++++++++++++-------
>  1 files changed, 152 insertions(+), 32 deletions(-)

This patch and the next one appear to be part of a larger series.
Feel free to take them through whatever tree you need to.

Acked-by: Grant Likely <grant.likely@xxxxxxxxxxxx>  (for both)

g.

> 
> diff --git a/drivers/spi/spi-omap2-mcspi.c b/drivers/spi/spi-omap2-mcspi.c
> index bb9274c..b2461d7 100644
> --- a/drivers/spi/spi-omap2-mcspi.c
> +++ b/drivers/spi/spi-omap2-mcspi.c
> @@ -20,6 +20,8 @@
>   * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
>   *
>   */
> +#define USE_DMA_ENGINE_RX
> +#define USE_DMA_ENGINE_TX
>  
>  #include <linux/kernel.h>
>  #include <linux/init.h>
> @@ -28,6 +30,7 @@
>  #include <linux/device.h>
>  #include <linux/delay.h>
>  #include <linux/dma-mapping.h>
> +#include <linux/dmaengine.h>
>  #include <linux/platform_device.h>
>  #include <linux/err.h>
>  #include <linux/clk.h>
> @@ -95,6 +98,8 @@
>  
>  /* We have 2 DMA channels per CS, one for RX and one for TX */
>  struct omap2_mcspi_dma {
> +	struct dma_chan *dma_tx;
> +	struct dma_chan *dma_rx;
>  	int dma_tx_channel;
>  	int dma_rx_channel;
>  
> @@ -290,6 +295,30 @@ static int mcspi_wait_for_reg_bit(void __iomem *reg, unsigned long bit)
>  	return 0;
>  }
>  
> +static void omap2_mcspi_rx_callback(void *data)
> +{
> +	struct spi_device *spi = data;
> +	struct omap2_mcspi *mcspi = spi_master_get_devdata(spi->master);
> +	struct omap2_mcspi_dma *mcspi_dma = &mcspi->dma_channels[spi->chip_select];
> +
> +	complete(&mcspi_dma->dma_rx_completion);
> +
> +	/* We must disable the DMA RX request */
> +	omap2_mcspi_set_dma_req(spi, 1, 0);
> +}
> +
> +static void omap2_mcspi_tx_callback(void *data)
> +{
> +	struct spi_device *spi = data;
> +	struct omap2_mcspi *mcspi = spi_master_get_devdata(spi->master);
> +	struct omap2_mcspi_dma *mcspi_dma = &mcspi->dma_channels[spi->chip_select];
> +
> +	complete(&mcspi_dma->dma_tx_completion);
> +
> +	/* We must disable the DMA TX request */
> +	omap2_mcspi_set_dma_req(spi, 0, 0);
> +}
> +
>  static unsigned
>  omap2_mcspi_txrx_dma(struct spi_device *spi, struct spi_transfer *xfer)
>  {
> @@ -304,6 +333,9 @@ omap2_mcspi_txrx_dma(struct spi_device *spi, struct spi_transfer *xfer)
>  	u8			* rx;
>  	const u8		* tx;
>  	void __iomem		*chstat_reg;
> +	struct dma_slave_config	cfg;
> +	enum dma_slave_buswidth width;
> +	unsigned es;
>  
>  	mcspi = spi_master_get_devdata(spi->master);
>  	mcspi_dma = &mcspi->dma_channels[spi->chip_select];
> @@ -311,6 +343,71 @@ omap2_mcspi_txrx_dma(struct spi_device *spi, struct spi_transfer *xfer)
>  
>  	chstat_reg = cs->base + OMAP2_MCSPI_CHSTAT0;
>  
> +	if (cs->word_len <= 8) {
> +		width = DMA_SLAVE_BUSWIDTH_1_BYTE;
> +		es = 1;
> +	} else if (cs->word_len <= 16) {
> +		width = DMA_SLAVE_BUSWIDTH_2_BYTES;
> +		es = 2;
> +	} else {
> +		width = DMA_SLAVE_BUSWIDTH_4_BYTES;
> +		es = 4;
> +	}
> +
> +	memset(&cfg, 0, sizeof(cfg));
> +	cfg.src_addr = cs->phys + OMAP2_MCSPI_RX0;
> +	cfg.dst_addr = cs->phys + OMAP2_MCSPI_TX0;
> +	cfg.src_addr_width = width;
> +	cfg.dst_addr_width = width;
> +	cfg.src_maxburst = 1;
> +	cfg.dst_maxburst = 1;
> +
> +	if (xfer->tx_buf && mcspi_dma->dma_tx) {
> +		struct dma_async_tx_descriptor *tx;
> +		struct scatterlist sg;
> +
> +		dmaengine_slave_config(mcspi_dma->dma_tx, &cfg);
> +
> +		sg_init_table(&sg, 1);
> +		sg_dma_address(&sg) = xfer->tx_dma;
> +		sg_dma_len(&sg) = xfer->len;
> +
> +		tx = dmaengine_prep_slave_sg(mcspi_dma->dma_tx, &sg, 1,
> +			DMA_MEM_TO_DEV, DMA_PREP_INTERRUPT | DMA_CTRL_ACK);
> +		if (tx) {
> +			tx->callback = omap2_mcspi_tx_callback;
> +			tx->callback_param = spi;
> +			dmaengine_submit(tx);
> +		} else {
> +			/* FIXME: fall back to PIO? */
> +		}
> +	}
> +
> +	if (xfer->rx_buf && mcspi_dma->dma_rx) {
> +		struct dma_async_tx_descriptor *tx;
> +		struct scatterlist sg;
> +		size_t len = xfer->len - es;
> +
> +		dmaengine_slave_config(mcspi_dma->dma_rx, &cfg);
> +
> +		if (l & OMAP2_MCSPI_CHCONF_TURBO)
> +			len -= es;
> +
> +		sg_init_table(&sg, 1);
> +		sg_dma_address(&sg) = xfer->rx_dma;
> +		sg_dma_len(&sg) = len;
> +
> +		tx = dmaengine_prep_slave_sg(mcspi_dma->dma_rx, &sg, 1,
> +			DMA_DEV_TO_MEM, DMA_PREP_INTERRUPT | DMA_CTRL_ACK);
> +		if (tx) {
> +			tx->callback = omap2_mcspi_rx_callback;
> +			tx->callback_param = spi;
> +			dmaengine_submit(tx);
> +		} else {
> +			/* FIXME: fall back to PIO? */
> +		}
> +	}
> +
>  	count = xfer->len;
>  	c = count;
>  	word_len = cs->word_len;
> @@ -332,7 +429,7 @@ omap2_mcspi_txrx_dma(struct spi_device *spi, struct spi_transfer *xfer)
>  		element_count = count >> 2;
>  	}
>  
> -	if (tx != NULL) {
> +	if (tx != NULL && mcspi_dma->dma_tx_channel != -1) {
>  		omap_set_dma_transfer_params(mcspi_dma->dma_tx_channel,
>  				data_type, element_count, 1,
>  				OMAP_DMA_SYNC_ELEMENT,
> @@ -347,7 +444,7 @@ omap2_mcspi_txrx_dma(struct spi_device *spi, struct spi_transfer *xfer)
>  				xfer->tx_dma, 0, 0);
>  	}
>  
> -	if (rx != NULL) {
> +	if (rx != NULL && mcspi_dma->dma_rx_channel != -1) {
>  		elements = element_count - 1;
>  		if (l & OMAP2_MCSPI_CHCONF_TURBO)
>  			elements--;
> @@ -367,12 +464,18 @@ omap2_mcspi_txrx_dma(struct spi_device *spi, struct spi_transfer *xfer)
>  	}
>  
>  	if (tx != NULL) {
> -		omap_start_dma(mcspi_dma->dma_tx_channel);
> +		if (mcspi_dma->dma_tx)
> +			dma_async_issue_pending(mcspi_dma->dma_tx);
> +		else
> +			omap_start_dma(mcspi_dma->dma_tx_channel);
>  		omap2_mcspi_set_dma_req(spi, 0, 1);
>  	}
>  
>  	if (rx != NULL) {
> -		omap_start_dma(mcspi_dma->dma_rx_channel);
> +		if (mcspi_dma->dma_rx)
> +			dma_async_issue_pending(mcspi_dma->dma_rx);
> +		else
> +			omap_start_dma(mcspi_dma->dma_rx_channel);
>  		omap2_mcspi_set_dma_req(spi, 1, 1);
>  	}
>  
> @@ -396,7 +499,10 @@ omap2_mcspi_txrx_dma(struct spi_device *spi, struct spi_transfer *xfer)
>  		dma_unmap_single(&spi->dev, xfer->rx_dma, count, DMA_FROM_DEVICE);
>  		omap2_mcspi_set_enable(spi, 0);
>  
> +		elements = element_count - 1;
> +
>  		if (l & OMAP2_MCSPI_CHCONF_TURBO) {
> +			elements--;
>  
>  			if (likely(mcspi_read_cs_reg(spi, OMAP2_MCSPI_CHSTAT0)
>  				   & OMAP2_MCSPI_CHSTAT_RXS)) {
> @@ -715,50 +821,58 @@ static int omap2_mcspi_setup_transfer(struct spi_device *spi,
>  
>  static void omap2_mcspi_dma_rx_callback(int lch, u16 ch_status, void *data)
>  {
> -	struct spi_device	*spi = data;
> -	struct omap2_mcspi	*mcspi;
> -	struct omap2_mcspi_dma	*mcspi_dma;
> -
> -	mcspi = spi_master_get_devdata(spi->master);
> -	mcspi_dma = &(mcspi->dma_channels[spi->chip_select]);
> -
> -	complete(&mcspi_dma->dma_rx_completion);
> -
> -	/* We must disable the DMA RX request */
> -	omap2_mcspi_set_dma_req(spi, 1, 0);
> +	omap2_mcspi_rx_callback(data);
>  }
>  
>  static void omap2_mcspi_dma_tx_callback(int lch, u16 ch_status, void *data)
>  {
> -	struct spi_device	*spi = data;
> -	struct omap2_mcspi	*mcspi;
> -	struct omap2_mcspi_dma	*mcspi_dma;
> -
> -	mcspi = spi_master_get_devdata(spi->master);
> -	mcspi_dma = &(mcspi->dma_channels[spi->chip_select]);
> -
> -	complete(&mcspi_dma->dma_tx_completion);
> -
> -	/* We must disable the DMA TX request */
> -	omap2_mcspi_set_dma_req(spi, 0, 0);
> +	omap2_mcspi_tx_callback(data);
>  }
>  
> +extern bool omap_dma_filter_fn(struct dma_chan *chan, void *param);
> +
>  static int omap2_mcspi_request_dma(struct spi_device *spi)
>  {
>  	struct spi_master	*master = spi->master;
>  	struct omap2_mcspi	*mcspi;
>  	struct omap2_mcspi_dma	*mcspi_dma;
> +	dma_cap_mask_t mask;
> +	unsigned sig;
>  
>  	mcspi = spi_master_get_devdata(master);
>  	mcspi_dma = mcspi->dma_channels + spi->chip_select;
>  
> +	init_completion(&mcspi_dma->dma_rx_completion);
> +	init_completion(&mcspi_dma->dma_tx_completion);
> +
> +	dma_cap_zero(mask);
> +	dma_cap_set(DMA_SLAVE, mask);
> +#ifdef USE_DMA_ENGINE_RX
> +	sig = mcspi_dma->dma_rx_sync_dev;
> +	mcspi_dma->dma_rx = dma_request_channel(mask, omap_dma_filter_fn, &sig);
> +	if (!mcspi_dma->dma_rx) {
> +		dev_err(&spi->dev, "no RX DMA engine channel for McSPI\n");
> +		return -EAGAIN;
> +	}
> +#else
>  	if (omap_request_dma(mcspi_dma->dma_rx_sync_dev, "McSPI RX",
>  			omap2_mcspi_dma_rx_callback, spi,
>  			&mcspi_dma->dma_rx_channel)) {
>  		dev_err(&spi->dev, "no RX DMA channel for McSPI\n");
>  		return -EAGAIN;
>  	}
> +#endif
>  
> +#ifdef USE_DMA_ENGINE_TX
> +	sig = mcspi_dma->dma_tx_sync_dev;
> +	mcspi_dma->dma_tx = dma_request_channel(mask, omap_dma_filter_fn, &sig);
> +	if (!mcspi_dma->dma_tx) {
> +		dev_err(&spi->dev, "no TX DMA engine channel for McSPI\n");
> +		dma_release_channel(mcspi_dma->dma_rx);
> +		mcspi_dma->dma_rx = NULL;
> +		return -EAGAIN;
> +	}
> +#else
>  	if (omap_request_dma(mcspi_dma->dma_tx_sync_dev, "McSPI TX",
>  			omap2_mcspi_dma_tx_callback, spi,
>  			&mcspi_dma->dma_tx_channel)) {
> @@ -767,9 +881,7 @@ static int omap2_mcspi_request_dma(struct spi_device *spi)
>  		dev_err(&spi->dev, "no TX DMA channel for McSPI\n");
>  		return -EAGAIN;
>  	}
> -
> -	init_completion(&mcspi_dma->dma_rx_completion);
> -	init_completion(&mcspi_dma->dma_tx_completion);
> +#endif
>  
>  	return 0;
>  }
> @@ -803,8 +915,8 @@ static int omap2_mcspi_setup(struct spi_device *spi)
>  			&omap2_mcspi_ctx[mcspi->master->bus_num - 1].cs);
>  	}
>  
> -	if (mcspi_dma->dma_rx_channel == -1
> -			|| mcspi_dma->dma_tx_channel == -1) {
> +	if ((!mcspi_dma->dma_rx && mcspi_dma->dma_rx_channel == -1) ||
> +	    (!mcspi_dma->dma_tx && mcspi_dma->dma_tx_channel == -1)) {
>  		ret = omap2_mcspi_request_dma(spi);
>  		if (ret < 0)
>  			return ret;
> @@ -839,6 +951,14 @@ static void omap2_mcspi_cleanup(struct spi_device *spi)
>  	if (spi->chip_select < spi->master->num_chipselect) {
>  		mcspi_dma = &mcspi->dma_channels[spi->chip_select];
>  
> +		if (mcspi_dma->dma_rx) {
> +			dma_release_channel(mcspi_dma->dma_rx);
> +			mcspi_dma->dma_rx = NULL;
> +		}
> +		if (mcspi_dma->dma_tx) {
> +			dma_release_channel(mcspi_dma->dma_tx);
> +			mcspi_dma->dma_tx = NULL;
> +		}
>  		if (mcspi_dma->dma_rx_channel != -1) {
>  			omap_free_dma(mcspi_dma->dma_rx_channel);
>  			mcspi_dma->dma_rx_channel = -1;
> -- 
> 1.7.4.4
> 
> 
> _______________________________________________
> linux-arm-kernel mailing list
> linux-arm-kernel@xxxxxxxxxxxxxxxxxxx
> http://lists.infradead.org/mailman/listinfo/linux-arm-kernel

-- 
Grant Likely, B.Sc, P.Eng.
Secret Lab Technologies, Ltd.
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