dmaengine: remove DMA_SG as it is dead code in kernel

There are no in kernel consumers for DMA_SG op. Removing operation,
dead code, and test code in dmatest.

Signed-off-by: Dave Jiang <[email protected]>
Reviewed-by: Linus Walleij <[email protected]>
Cc: Gary Hook <[email protected]>
Cc: Ludovic Desroches <[email protected]>
Cc: Kedareswara rao Appana <[email protected]>
Cc: Li Yang <[email protected]>
Cc: Michal Simek <[email protected]>
Signed-off-by: Vinod Koul <[email protected]>

Author: davejiang

Documentation/dmaengine/provider.txt

@@ -181,13 +181,6 @@ Currently, the types available are:
     - Used by the client drivers to register a callback that will be
       called on a regular basis through the DMA controller interrupt
 
-  * DMA_SG
-    - The device supports memory to memory scatter-gather
-      transfers.
-    - Even though a plain memcpy can look like a particular case of a
-      scatter-gather transfer, with a single chunk to transfer, it's a
-      distinct transaction type in the mem2mem transfers case
-
   * DMA_PRIVATE
     - The devices only supports slave transfers, and as such isn't
       available for async transfers.

drivers/crypto/ccp/ccp-dmaengine.c

@@ -502,27 +502,6 @@ static struct dma_async_tx_descriptor *ccp_prep_dma_memcpy(
 	return &desc->tx_desc;
 }
 
-static struct dma_async_tx_descriptor *ccp_prep_dma_sg(
-	struct dma_chan *dma_chan, struct scatterlist *dst_sg,
-	unsigned int dst_nents, struct scatterlist *src_sg,
-	unsigned int src_nents, unsigned long flags)
-{
-	struct ccp_dma_chan *chan = container_of(dma_chan, struct ccp_dma_chan,
-						 dma_chan);
-	struct ccp_dma_desc *desc;
-
-	dev_dbg(chan->ccp->dev,
-		"%s - src=%p, src_nents=%u dst=%p, dst_nents=%u, flags=%#lx\n",
-		__func__, src_sg, src_nents, dst_sg, dst_nents, flags);
-
-	desc = ccp_create_desc(dma_chan, dst_sg, dst_nents, src_sg, src_nents,
-			       flags);
-	if (!desc)
-		return NULL;
-
-	return &desc->tx_desc;
-}
-
 static struct dma_async_tx_descriptor *ccp_prep_dma_interrupt(
 	struct dma_chan *dma_chan, unsigned long flags)
 {
@@ -704,7 +683,6 @@ int ccp_dmaengine_register(struct ccp_device *ccp)
 	dma_dev->directions = DMA_MEM_TO_MEM;
 	dma_dev->residue_granularity = DMA_RESIDUE_GRANULARITY_DESCRIPTOR;
 	dma_cap_set(DMA_MEMCPY, dma_dev->cap_mask);
-	dma_cap_set(DMA_SG, dma_dev->cap_mask);
 	dma_cap_set(DMA_INTERRUPT, dma_dev->cap_mask);
 
 	/* The DMA channels for this device can be set to public or private,
@@ -740,7 +718,6 @@ int ccp_dmaengine_register(struct ccp_device *ccp)
 
 	dma_dev->device_free_chan_resources = ccp_free_chan_resources;
 	dma_dev->device_prep_dma_memcpy = ccp_prep_dma_memcpy;
-	dma_dev->device_prep_dma_sg = ccp_prep_dma_sg;
 	dma_dev->device_prep_dma_interrupt = ccp_prep_dma_interrupt;
 	dma_dev->device_issue_pending = ccp_issue_pending;
 	dma_dev->device_tx_status = ccp_tx_status;

drivers/dma/at_hdmac.c

@@ -1202,138 +1202,6 @@ atc_prep_slave_sg(struct dma_chan *chan, struct scatterlist *sgl,
 	return NULL;
 }
 
-/**
- * atc_prep_dma_sg - prepare memory to memory scather-gather operation
- * @chan: the channel to prepare operation on
- * @dst_sg: destination scatterlist
- * @dst_nents: number of destination scatterlist entries
- * @src_sg: source scatterlist
- * @src_nents: number of source scatterlist entries
- * @flags: tx descriptor status flags
- */
-static struct dma_async_tx_descriptor *
-atc_prep_dma_sg(struct dma_chan *chan,
-		struct scatterlist *dst_sg, unsigned int dst_nents,
-		struct scatterlist *src_sg, unsigned int src_nents,
-		unsigned long flags)
-{
-	struct at_dma_chan	*atchan = to_at_dma_chan(chan);
-	struct at_desc		*desc = NULL;
-	struct at_desc		*first = NULL;
-	struct at_desc		*prev = NULL;
-	unsigned int		src_width;
-	unsigned int		dst_width;
-	size_t			xfer_count;
-	u32			ctrla;
-	u32			ctrlb;
-	size_t			dst_len = 0, src_len = 0;
-	dma_addr_t		dst = 0, src = 0;
-	size_t			len = 0, total_len = 0;
-
-	if (unlikely(dst_nents == 0 || src_nents == 0))
-		return NULL;
-
-	if (unlikely(dst_sg == NULL || src_sg == NULL))
-		return NULL;
-
-	ctrlb =   ATC_DEFAULT_CTRLB | ATC_IEN
-		| ATC_SRC_ADDR_MODE_INCR
-		| ATC_DST_ADDR_MODE_INCR
-		| ATC_FC_MEM2MEM;
-
-	/*
-	 * loop until there is either no more source or no more destination
-	 * scatterlist entry
-	 */
-	while (true) {
-
-		/* prepare the next transfer */
-		if (dst_len == 0) {
-
-			/* no more destination scatterlist entries */
-			if (!dst_sg || !dst_nents)
-				break;
-
-			dst = sg_dma_address(dst_sg);
-			dst_len = sg_dma_len(dst_sg);
-
-			dst_sg = sg_next(dst_sg);
-			dst_nents--;
-		}
-
-		if (src_len == 0) {
-
-			/* no more source scatterlist entries */
-			if (!src_sg || !src_nents)
-				break;
-
-			src = sg_dma_address(src_sg);
-			src_len = sg_dma_len(src_sg);
-
-			src_sg = sg_next(src_sg);
-			src_nents--;
-		}
-
-		len = min_t(size_t, src_len, dst_len);
-		if (len == 0)
-			continue;
-
-		/* take care for the alignment */
-		src_width = dst_width = atc_get_xfer_width(src, dst, len);
-
-		ctrla = ATC_SRC_WIDTH(src_width) |
-			ATC_DST_WIDTH(dst_width);
-
-		/*
-		 * The number of transfers to set up refer to the source width
-		 * that depends on the alignment.
-		 */
-		xfer_count = len >> src_width;
-		if (xfer_count > ATC_BTSIZE_MAX) {
-			xfer_count = ATC_BTSIZE_MAX;
-			len = ATC_BTSIZE_MAX << src_width;
-		}
-
-		/* create the transfer */
-		desc = atc_desc_get(atchan);
-		if (!desc)
-			goto err_desc_get;
-
-		desc->lli.saddr = src;
-		desc->lli.daddr = dst;
-		desc->lli.ctrla = ctrla | xfer_count;
-		desc->lli.ctrlb = ctrlb;
-
-		desc->txd.cookie = 0;
-		desc->len = len;
-
-		atc_desc_chain(&first, &prev, desc);
-
-		/* update the lengths and addresses for the next loop cycle */
-		dst_len -= len;
-		src_len -= len;
-		dst += len;
-		src += len;
-
-		total_len += len;
-	}
-
-	/* First descriptor of the chain embedds additional information */
-	first->txd.cookie = -EBUSY;
-	first->total_len = total_len;
-
-	/* set end-of-link to the last link descriptor of list*/
-	set_desc_eol(desc);
-
-	first->txd.flags = flags; /* client is in control of this ack */
-
-	return &first->txd;
-
-err_desc_get:
-	atc_desc_put(atchan, first);
-	return NULL;
-}
-
 /**
  * atc_dma_cyclic_check_values
  * Check for too big/unaligned periods and unaligned DMA buffer
@@ -1933,14 +1801,12 @@ static int __init at_dma_probe(struct platform_device *pdev)
 
 	/* setup platform data for each SoC */
 	dma_cap_set(DMA_MEMCPY, at91sam9rl_config.cap_mask);
-	dma_cap_set(DMA_SG, at91sam9rl_config.cap_mask);
 	dma_cap_set(DMA_INTERLEAVE, at91sam9g45_config.cap_mask);
 	dma_cap_set(DMA_MEMCPY, at91sam9g45_config.cap_mask);
 	dma_cap_set(DMA_MEMSET, at91sam9g45_config.cap_mask);
 	dma_cap_set(DMA_MEMSET_SG, at91sam9g45_config.cap_mask);
 	dma_cap_set(DMA_PRIVATE, at91sam9g45_config.cap_mask);
 	dma_cap_set(DMA_SLAVE, at91sam9g45_config.cap_mask);
-	dma_cap_set(DMA_SG, at91sam9g45_config.cap_mask);
 
 	/* get DMA parameters from controller type */
 	plat_dat = at_dma_get_driver_data(pdev);
@@ -2078,16 +1944,12 @@ static int __init at_dma_probe(struct platform_device *pdev)
 		atdma->dma_common.residue_granularity = DMA_RESIDUE_GRANULARITY_BURST;
 	}
 
-	if (dma_has_cap(DMA_SG, atdma->dma_common.cap_mask))
-		atdma->dma_common.device_prep_dma_sg = atc_prep_dma_sg;
-
 	dma_writel(atdma, EN, AT_DMA_ENABLE);
 
-	dev_info(&pdev->dev, "Atmel AHB DMA Controller ( %s%s%s%s), %d channels\n",
+	dev_info(&pdev->dev, "Atmel AHB DMA Controller ( %s%s%s), %d channels\n",
 	  dma_has_cap(DMA_MEMCPY, atdma->dma_common.cap_mask) ? "cpy " : "",
 	  dma_has_cap(DMA_MEMSET, atdma->dma_common.cap_mask) ? "set " : "",
 	  dma_has_cap(DMA_SLAVE, atdma->dma_common.cap_mask)  ? "slave " : "",
-	  dma_has_cap(DMA_SG, atdma->dma_common.cap_mask)  ? "sg-cpy " : "",
 	  plat_dat->nr_channels);
 
 	dma_async_device_register(&atdma->dma_common);

drivers/dma/dmaengine.c

@@ -937,8 +937,6 @@ int dma_async_device_register(struct dma_device *device)
 		!device->device_prep_dma_memset);
 	BUG_ON(dma_has_cap(DMA_INTERRUPT, device->cap_mask) &&
 		!device->device_prep_dma_interrupt);
-	BUG_ON(dma_has_cap(DMA_SG, device->cap_mask) &&
-		!device->device_prep_dma_sg);
 	BUG_ON(dma_has_cap(DMA_CYCLIC, device->cap_mask) &&
 		!device->device_prep_dma_cyclic);
 	BUG_ON(dma_has_cap(DMA_INTERLEAVE, device->cap_mask) &&

drivers/dma/dmatest.c

@@ -52,15 +52,10 @@ module_param(iterations, uint, S_IRUGO | S_IWUSR);
 MODULE_PARM_DESC(iterations,
 		"Iterations before stopping test (default: infinite)");
 
-static unsigned int sg_buffers = 1;
-module_param(sg_buffers, uint, S_IRUGO | S_IWUSR);
-MODULE_PARM_DESC(sg_buffers,
-		"Number of scatter gather buffers (default: 1)");
-
 static unsigned int dmatest;
 module_param(dmatest, uint, S_IRUGO | S_IWUSR);
 MODULE_PARM_DESC(dmatest,
-		"dmatest 0-memcpy 1-slave_sg 2-memset (default: 0)");
+		"dmatest 0-memcpy 1-memset (default: 0)");
 
 static unsigned int xor_sources = 3;
 module_param(xor_sources, uint, S_IRUGO | S_IWUSR);
@@ -471,9 +466,6 @@ static int dmatest_func(void *data)
 		align = dev->fill_align;
 		src_cnt = dst_cnt = 1;
 		is_memset = true;
-	} else if (thread->type == DMA_SG) {
-		align = dev->copy_align;
-		src_cnt = dst_cnt = sg_buffers;
 	} else if (thread->type == DMA_XOR) {
 		/* force odd to ensure dst = src */
 		src_cnt = min_odd(params->xor_sources | 1, dev->max_xor);
@@ -553,8 +545,6 @@ static int dmatest_func(void *data)
 		dma_addr_t srcs[src_cnt];
 		dma_addr_t *dsts;
 		unsigned int src_off, dst_off, len;
-		struct scatterlist tx_sg[src_cnt];
-		struct scatterlist rx_sg[src_cnt];
 
 		total_tests++;
 
@@ -650,15 +640,6 @@ static int dmatest_func(void *data)
 			um->bidi_cnt++;
 		}
 
-		sg_init_table(tx_sg, src_cnt);
-		sg_init_table(rx_sg, src_cnt);
-		for (i = 0; i < src_cnt; i++) {
-			sg_dma_address(&rx_sg[i]) = srcs[i];
-			sg_dma_address(&tx_sg[i]) = dsts[i] + dst_off;
-			sg_dma_len(&tx_sg[i]) = len;
-			sg_dma_len(&rx_sg[i]) = len;
-		}
-
 		if (thread->type == DMA_MEMCPY)
 			tx = dev->device_prep_dma_memcpy(chan,
 							 dsts[0] + dst_off,
@@ -668,9 +649,6 @@ static int dmatest_func(void *data)
 						dsts[0] + dst_off,
 						*(thread->srcs[0] + src_off),
 						len, flags);
-		else if (thread->type == DMA_SG)
-			tx = dev->device_prep_dma_sg(chan, tx_sg, src_cnt,
-						     rx_sg, src_cnt, flags);
 		else if (thread->type == DMA_XOR)
 			tx = dev->device_prep_dma_xor(chan,
 						      dsts[0] + dst_off,
@@ -853,8 +831,6 @@ static int dmatest_add_threads(struct dmatest_info *info,
 		op = "copy";
 	else if (type == DMA_MEMSET)
 		op = "set";
-	else if (type == DMA_SG)
-		op = "sg";
 	else if (type == DMA_XOR)
 		op = "xor";
 	else if (type == DMA_PQ)
@@ -916,15 +892,8 @@ static int dmatest_add_channel(struct dmatest_info *info,
 	}
 
 	if (dma_has_cap(DMA_MEMSET, dma_dev->cap_mask)) {
-		if (dmatest == 2) {
-			cnt = dmatest_add_threads(info, dtc, DMA_MEMSET);
-			thread_count += cnt > 0 ? cnt : 0;
-		}
-	}
-
-	if (dma_has_cap(DMA_SG, dma_dev->cap_mask)) {
 		if (dmatest == 1) {
-			cnt = dmatest_add_threads(info, dtc, DMA_SG);
+			cnt = dmatest_add_threads(info, dtc, DMA_MEMSET);
 			thread_count += cnt > 0 ? cnt : 0;
 		}
 	}
@@ -1002,7 +971,6 @@ static void run_threaded_test(struct dmatest_info *info)
 	request_channels(info, DMA_MEMCPY);
 	request_channels(info, DMA_MEMSET);
 	request_channels(info, DMA_XOR);
-	request_channels(info, DMA_SG);
 	request_channels(info, DMA_PQ);
 }