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Commit ff39988a authored by Siva Yerramreddy's avatar Siva Yerramreddy Committed by Greg Kroah-Hartman
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dma: Add support to program MIC x100 status descriptiors 



The MIC X100 DMA engine has a special status descriptor which writes
an 8 byte value to a destination location.  This is used to signal
completion of all DMA descriptors prior to the status descriptor.
This patch add a new DMA engine API which enables updating a
destination address with an 8 byte immediate data value.

Reviewed-by: default avatarNikhil Rao <nikhil.rao@intel.com>
Reviewed-by: default avatarAshutosh Dixit <ashutosh.dixit@intel.com>
Signed-off-by: default avatarLawrynowicz, Jacek <jacek.lawrynowicz@intel.com>
Signed-off-by: default avatarSudeep Dutt <sudeep.dutt@intel.com>
Signed-off-by: default avatarSiva Yerramreddy <yshivakrishna@gmail.com>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent 353649e5

drivers/dma/mic_x100_dma.c

+38 −1
Original line number Diff line number Diff line
@@ -193,8 +193,16 @@ static void mic_dma_prog_intr(struct mic_dma_chan *ch) 
static int mic_dma_do_dma(struct mic_dma_chan *ch, int flags, dma_addr_t src,

			  dma_addr_t dst, size_t len)

{

	if (-ENOMEM == mic_dma_prog_memcpy_desc(ch, src, dst, len))

	if (len && -ENOMEM == mic_dma_prog_memcpy_desc(ch, src, dst, len)) {

		return -ENOMEM;

	} else {

		/* 3 is the maximum number of status descriptors */

		int ret = mic_dma_avail_desc_ring_space(ch, 3);



		if (ret < 0)

			return ret;

	}



	/* Above mic_dma_prog_memcpy_desc() makes sure we have enough space */

	if (flags & DMA_PREP_FENCE) {

		mic_dma_prep_status_desc(&ch->desc_ring[ch->head], 0,
@@ -270,6 +278,33 @@ allocate_tx(struct mic_dma_chan *ch) 
	return tx;

}



/* Program a status descriptor with dst as address and value to be written */

static struct dma_async_tx_descriptor *

mic_dma_prep_status_lock(struct dma_chan *ch, dma_addr_t dst, u64 src_val,

			 unsigned long flags)

{

	struct mic_dma_chan *mic_ch = to_mic_dma_chan(ch);

	int result;



	spin_lock(&mic_ch->prep_lock);

	result = mic_dma_avail_desc_ring_space(mic_ch, 4);

	if (result < 0)

		goto error;

	mic_dma_prep_status_desc(&mic_ch->desc_ring[mic_ch->head], src_val, dst,

				 false);

	mic_dma_hw_ring_inc_head(mic_ch);

	result = mic_dma_do_dma(mic_ch, flags, 0, 0, 0);

	if (result < 0)

		goto error;



	return allocate_tx(mic_ch);

error:

	dev_err(mic_dma_ch_to_device(mic_ch),

		"Error enqueueing dma status descriptor, error=%d\n", result);

	spin_unlock(&mic_ch->prep_lock);

	return NULL;

}



/*

 * Prepare a memcpy descriptor to be added to the ring.

 * Note that the temporary descriptor adds an extra overhead of copying the
@@ -587,6 +622,8 @@ static int mic_dma_register_dma_device(struct mic_dma_device *mic_dma_dev, 
		mic_dma_free_chan_resources;

	mic_dma_dev->dma_dev.device_tx_status = mic_dma_tx_status;

	mic_dma_dev->dma_dev.device_prep_dma_memcpy = mic_dma_prep_memcpy_lock;

	mic_dma_dev->dma_dev.device_prep_dma_imm_data =

		mic_dma_prep_status_lock;

	mic_dma_dev->dma_dev.device_prep_dma_interrupt =

		mic_dma_prep_interrupt_lock;

	mic_dma_dev->dma_dev.device_issue_pending = mic_dma_issue_pending;

include/linux/dmaengine.h

+4 −0
Original line number Diff line number Diff line
@@ -645,6 +645,7 @@ enum dmaengine_alignment { 
 *	The function takes a buffer of size buf_len. The callback function will

 *	be called after period_len bytes have been transferred.

 * @device_prep_interleaved_dma: Transfer expression in a generic way.

 * @device_prep_dma_imm_data: DMA's 8 byte immediate data to the dst address

 * @device_config: Pushes a new configuration to a channel, return 0 or an error

 *	code

 * @device_pause: Pauses any transfer happening on a channel. Returns
@@ -727,6 +728,9 @@ struct dma_device { 
	struct dma_async_tx_descriptor *(*device_prep_interleaved_dma)(

		struct dma_chan *chan, struct dma_interleaved_template *xt,

		unsigned long flags);

	struct dma_async_tx_descriptor *(*device_prep_dma_imm_data)(

		struct dma_chan *chan, dma_addr_t dst, u64 data,

		unsigned long flags);



	int (*device_config)(struct dma_chan *chan,

			     struct dma_slave_config *config);