[PATCH 3/3] dmaengine: IOATDMA: Allocate DMA descriptor ring in contig DMA memory

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Future IOATDMA hardware will take advantage of descriptors residing in
contiguous memory. Setting the descriptor ring in max config DMA memory
of 2MB. Each channel will need 2 of these chunks. This should provide 64k
of 64B descriptors.

Signed-off-by: Dave Jiang <dave.jiang@xxxxxxxxx>
---
 drivers/dma/ioat/dma.c  |   75 ++++++++++++++++++++++++++++++++++++-----------
 drivers/dma/ioat/dma.h  |   11 ++++++-
 drivers/dma/ioat/hw.h   |    2 +
 drivers/dma/ioat/init.c |   27 ++++++++---------
 4 files changed, 81 insertions(+), 34 deletions(-)

diff --git a/drivers/dma/ioat/dma.c b/drivers/dma/ioat/dma.c
index a80b391..8cd56f4 100644
--- a/drivers/dma/ioat/dma.c
+++ b/drivers/dma/ioat/dma.c
@@ -31,6 +31,7 @@
 #include <linux/dma-mapping.h>
 #include <linux/workqueue.h>
 #include <linux/prefetch.h>
+#include <linux/sizes.h>
 #include "dma.h"
 #include "registers.h"
 #include "hw.h"
@@ -290,24 +291,30 @@ static dma_cookie_t ioat_tx_submit_unlock(struct dma_async_tx_descriptor *tx)
 }
 
 static struct ioat_ring_ent *
-ioat_alloc_ring_ent(struct dma_chan *chan, gfp_t flags)
+ioat_alloc_ring_ent(struct dma_chan *chan, int idx, gfp_t flags)
 {
 	struct ioat_dma_descriptor *hw;
 	struct ioat_ring_ent *desc;
 	struct ioatdma_device *ioat_dma;
+	struct ioatdma_chan *ioat_chan = to_ioat_chan(chan);
+	int chunk;
 	dma_addr_t phys;
+	u8 *pos;
+	off_t offs;
 
 	ioat_dma = to_ioatdma_device(chan->device);
-	hw = dma_pool_alloc(ioat_dma->dma_pool, flags, &phys);
-	if (!hw)
-		return NULL;
+
+	chunk = idx / IOAT_DESCS_PER_2M;
+	idx &= (IOAT_DESCS_PER_2M - 1);
+	offs = idx * IOAT_DESC_SZ;
+	pos = (u8 *)ioat_chan->descs[chunk].virt + offs;
+	phys = ioat_chan->descs[chunk].hw + offs;
+	hw = (struct ioat_dma_descriptor *)pos;
 	memset(hw, 0, sizeof(*hw));
 
 	desc = kmem_cache_zalloc(ioat_cache, flags);
-	if (!desc) {
-		dma_pool_free(ioat_dma->dma_pool, hw, phys);
+	if (!desc)
 		return NULL;
-	}
 
 	dma_async_tx_descriptor_init(&desc->txd, chan);
 	desc->txd.tx_submit = ioat_tx_submit_unlock;
@@ -318,29 +325,63 @@ ioat_alloc_ring_ent(struct dma_chan *chan, gfp_t flags)
 
 void ioat_free_ring_ent(struct ioat_ring_ent *desc, struct dma_chan *chan)
 {
-	struct ioatdma_device *ioat_dma;
-
-	ioat_dma = to_ioatdma_device(chan->device);
-	dma_pool_free(ioat_dma->dma_pool, desc->hw, desc->txd.phys);
 	kmem_cache_free(ioat_cache, desc);
 }
 
 struct ioat_ring_ent **
 ioat_alloc_ring(struct dma_chan *c, int order, gfp_t flags)
 {
+	struct ioatdma_chan *ioat_chan = to_ioat_chan(c);
 	struct ioat_ring_ent **ring;
-	int descs = 1 << order;
-	int i;
+	int total_descs = 1 << order;
+	int i, chunks;
 
 	/* allocate the array to hold the software ring */
-	ring = kcalloc(descs, sizeof(*ring), flags);
+	ring = kcalloc(total_descs, sizeof(*ring), flags);
 	if (!ring)
 		return NULL;
-	for (i = 0; i < descs; i++) {
-		ring[i] = ioat_alloc_ring_ent(c, flags);
+
+	ioat_chan->desc_chunks = chunks = (total_descs * IOAT_DESC_SZ) / SZ_2M;
+
+	for (i = 0; i < chunks; i++) {
+		struct ioat_descs *descs = &ioat_chan->descs[i];
+
+		descs->virt = dma_alloc_coherent(to_dev(ioat_chan),
+						 SZ_2M, &descs->hw, flags);
+		if (!descs->virt && (i > 0)) {
+			int idx;
+
+			for (idx = 0; idx < i; idx++) {
+				dma_free_coherent(to_dev(ioat_chan), SZ_2M,
+						  descs->virt, descs->hw);
+				descs->virt = NULL;
+				descs->hw = 0;
+			}
+
+			ioat_chan->desc_chunks = 0;
+			kfree(ring);
+			return NULL;
+		}
+	}
+
+	for (i = 0; i < total_descs; i++) {
+		ring[i] = ioat_alloc_ring_ent(c, i, flags);
 		if (!ring[i]) {
+			int idx;
+
 			while (i--)
 				ioat_free_ring_ent(ring[i], c);
+
+			for (idx = 0; idx < ioat_chan->desc_chunks; idx++) {
+				dma_free_coherent(to_dev(ioat_chan),
+						  SZ_2M,
+						  ioat_chan->descs[idx].virt,
+						  ioat_chan->descs[idx].hw);
+				ioat_chan->descs[idx].virt = NULL;
+				ioat_chan->descs[idx].hw = 0;
+			}
+
+			ioat_chan->desc_chunks = 0;
 			kfree(ring);
 			return NULL;
 		}
@@ -348,7 +389,7 @@ ioat_alloc_ring(struct dma_chan *c, int order, gfp_t flags)
 	}
 
 	/* link descs */
-	for (i = 0; i < descs-1; i++) {
+	for (i = 0; i < total_descs-1; i++) {
 		struct ioat_ring_ent *next = ring[i+1];
 		struct ioat_dma_descriptor *hw = ring[i]->hw;
 
diff --git a/drivers/dma/ioat/dma.h b/drivers/dma/ioat/dma.h
index 5f2f9fb..57a9b83 100644
--- a/drivers/dma/ioat/dma.h
+++ b/drivers/dma/ioat/dma.h
@@ -62,7 +62,6 @@ enum ioat_irq_mode {
  * struct ioatdma_device - internal representation of a IOAT device
  * @pdev: PCI-Express device
  * @reg_base: MMIO register space base address
- * @dma_pool: for allocating DMA descriptors
  * @completion_pool: DMA buffers for completion ops
  * @sed_hw_pool: DMA super descriptor pools
  * @dma_dev: embedded struct dma_device
@@ -76,7 +75,6 @@ enum ioat_irq_mode {
 struct ioatdma_device {
 	struct pci_dev *pdev;
 	void __iomem *reg_base;
-	struct dma_pool *dma_pool;
 	struct dma_pool *completion_pool;
 #define MAX_SED_POOLS	5
 	struct dma_pool *sed_hw_pool[MAX_SED_POOLS];
@@ -90,6 +88,11 @@ struct ioatdma_device {
 	u32 cap;
 };
 
+struct ioat_descs {
+	void *virt;
+	dma_addr_t hw;
+};
+
 struct ioatdma_chan {
 	struct dma_chan dma_chan;
 	void __iomem *reg_base;
@@ -132,6 +135,8 @@ struct ioatdma_chan {
 	u16 produce;
 	struct ioat_ring_ent **ring;
 	spinlock_t prep_lock;
+	struct ioat_descs descs[2];
+	int desc_chunks;
 };
 
 struct ioat_sysfs_entry {
@@ -301,6 +306,8 @@ static inline bool is_ioat_bug(unsigned long err)
 }
 
 #define IOAT_MAX_ORDER 16
+#define IOAT_MAX_DESCS 65536
+#define IOAT_DESCS_PER_2M 32768
 
 static inline u32 ioat_ring_size(struct ioatdma_chan *ioat_chan)
 {
diff --git a/drivers/dma/ioat/hw.h b/drivers/dma/ioat/hw.h
index 690e3b4..8e67895 100644
--- a/drivers/dma/ioat/hw.h
+++ b/drivers/dma/ioat/hw.h
@@ -73,6 +73,8 @@
 
 int system_has_dca_enabled(struct pci_dev *pdev);
 
+#define IOAT_DESC_SZ	64
+
 struct ioat_dma_descriptor {
 	uint32_t	size;
 	union {
diff --git a/drivers/dma/ioat/init.c b/drivers/dma/ioat/init.c
index 6636920..efdee1a 100644
--- a/drivers/dma/ioat/init.c
+++ b/drivers/dma/ioat/init.c
@@ -28,6 +28,7 @@
 #include <linux/prefetch.h>
 #include <linux/dca.h>
 #include <linux/aer.h>
+#include <linux/sizes.h>
 #include "dma.h"
 #include "registers.h"
 #include "hw.h"
@@ -496,15 +497,6 @@ static int ioat_probe(struct ioatdma_device *ioat_dma)
 	struct pci_dev *pdev = ioat_dma->pdev;
 	struct device *dev = &pdev->dev;
 
-	/* DMA coherent memory pool for DMA descriptor allocations */
-	ioat_dma->dma_pool = dma_pool_create("dma_desc_pool", dev,
-					     sizeof(struct ioat_dma_descriptor),
-					     64, 0);
-	if (!ioat_dma->dma_pool) {
-		err = -ENOMEM;
-		goto err_dma_pool;
-	}
-
 	ioat_dma->completion_pool = dma_pool_create("completion_pool", dev,
 						    sizeof(u64),
 						    SMP_CACHE_BYTES,
@@ -512,7 +504,7 @@ static int ioat_probe(struct ioatdma_device *ioat_dma)
 
 	if (!ioat_dma->completion_pool) {
 		err = -ENOMEM;
-		goto err_completion_pool;
+		goto err_out;
 	}
 
 	ioat_enumerate_channels(ioat_dma);
@@ -539,9 +531,7 @@ err_self_test:
 	ioat_disable_interrupts(ioat_dma);
 err_setup_interrupts:
 	dma_pool_destroy(ioat_dma->completion_pool);
-err_completion_pool:
-	dma_pool_destroy(ioat_dma->dma_pool);
-err_dma_pool:
+err_out:
 	return err;
 }
 
@@ -552,7 +542,6 @@ static int ioat_register(struct ioatdma_device *ioat_dma)
 	if (err) {
 		ioat_disable_interrupts(ioat_dma);
 		dma_pool_destroy(ioat_dma->completion_pool);
-		dma_pool_destroy(ioat_dma->dma_pool);
 	}
 
 	return err;
@@ -568,7 +557,6 @@ static void ioat_dma_remove(struct ioatdma_device *ioat_dma)
 
 	dma_async_device_unregister(dma);
 
-	dma_pool_destroy(ioat_dma->dma_pool);
 	dma_pool_destroy(ioat_dma->completion_pool);
 
 	INIT_LIST_HEAD(&dma->channels);
@@ -658,6 +646,15 @@ static void ioat_free_chan_resources(struct dma_chan *c)
 		ioat_free_ring_ent(desc, c);
 	}
 
+	for (i = 0; i < ioat_chan->desc_chunks; i++) {
+		dma_free_coherent(to_dev(ioat_chan), SZ_2M,
+				  ioat_chan->descs[i].virt,
+				  ioat_chan->descs[i].hw);
+		ioat_chan->descs[i].virt = NULL;
+		ioat_chan->descs[i].hw = 0;
+	}
+	ioat_chan->desc_chunks = 0;
+
 	kfree(ioat_chan->ring);
 	ioat_chan->ring = NULL;
 	ioat_chan->alloc_order = 0;

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