ioat2,3: convert to a true ring buffer

Replace the current linked list munged into a ring with a native ring
buffer implementation.  The benefit of this approach is reduced overhead
as many parameters can be derived from ring position with simple pointer
comparisons and descriptor allocation/freeing becomes just a
manipulation of head/tail pointers.

It requires a contiguous allocation for the software descriptor
information.

Since this arrangement is significantly different from the ioat1 chain,
move ioat2,3 support into its own file and header.  Common routines are
exported from driver/dma/ioat/dma.[ch].
Signed-off-by: Maciej Sosnowski <maciej.sosnowski@intel.com>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>

drivers/dma/ioat/Makefile

 obj-$(CONFIG_INTEL_IOATDMA) += ioatdma.o
-ioatdma-objs := pci.o dma.o dca.o
+ioatdma-objs := pci.o dma.o dma_v2.o dca.o

drivers/dma/ioat/dma.h

@@ -62,6 +62,7 @@
  * @idx: per channel data
  * @dca: direct cache access context
  * @intr_quirk: interrupt setup quirk (for ioat_v1 devices)
+ * @enumerate_channels: hw version specific channel enumeration
  */
 
 struct ioatdma_device {
@@ -76,6 +77,7 @@ struct ioatdma_device {
 	struct ioat_chan_common *idx[4];
 	struct dca_provider *dca;
 	void (*intr_quirk)(struct ioatdma_device *device);
+	int (*enumerate_channels)(struct ioatdma_device *device);
 };
 
 struct ioat_chan_common {
@@ -106,6 +108,7 @@ struct ioat_chan_common {
 	struct tasklet_struct cleanup_task;
 };
 
+
 /**
  * struct ioat_dma_chan - internal representation of a DMA channel
  */
@@ -119,7 +122,6 @@ struct ioat_dma_chan {
 	struct list_head used_desc;
 
 	int pending;
-	u16 dmacount;
 	u16 desccount;
 };
 
@@ -135,6 +137,33 @@ static inline struct ioat_dma_chan *to_ioat_chan(struct dma_chan *c)
 	return container_of(chan, struct ioat_dma_chan, base);
 }
 
+/**
+ * ioat_is_complete - poll the status of an ioat transaction
+ * @c: channel handle
+ * @cookie: transaction identifier
+ * @done: if set, updated with last completed transaction
+ * @used: if set, updated with last used transaction
+ */
+static inline enum dma_status
+ioat_is_complete(struct dma_chan *c, dma_cookie_t cookie,
+		 dma_cookie_t *done, dma_cookie_t *used)
+{
+	struct ioat_chan_common *chan = to_chan_common(c);
+	dma_cookie_t last_used;
+	dma_cookie_t last_complete;
+
+	last_used = c->cookie;
+	last_complete = chan->completed_cookie;
+	chan->watchdog_tcp_cookie = cookie;
+
+	if (done)
+		*done = last_complete;
+	if (used)
+		*used = last_used;
+
+	return dma_async_is_complete(cookie, last_complete, last_used);
+}
+
 /* wrapper around hardware descriptor format + additional software fields */
 
 /**
@@ -162,11 +191,22 @@ static inline void ioat_set_tcp_copy_break(unsigned long copybreak)
 	#endif
 }
 
+static inline struct ioat_chan_common *
+ioat_chan_by_index(struct ioatdma_device *device, int index)
+{
+	return device->idx[index];
+}
+
+int ioat_probe(struct ioatdma_device *device);
+int ioat_register(struct ioatdma_device *device);
 int ioat1_dma_probe(struct ioatdma_device *dev, int dca);
-int ioat2_dma_probe(struct ioatdma_device *dev, int dca);
-int ioat3_dma_probe(struct ioatdma_device *dev, int dca);
 void ioat_dma_remove(struct ioatdma_device *device);
 struct dca_provider *ioat_dca_init(struct pci_dev *pdev, void __iomem *iobase);
-struct dca_provider *ioat2_dca_init(struct pci_dev *pdev, void __iomem *iobase);
-struct dca_provider *ioat3_dca_init(struct pci_dev *pdev, void __iomem *iobase);
+unsigned long ioat_get_current_completion(struct ioat_chan_common *chan);
+void ioat_init_channel(struct ioatdma_device *device,
+		       struct ioat_chan_common *chan, int idx,
+		       work_func_t work_fn, void (*tasklet)(unsigned long),
+		       unsigned long tasklet_data);
+void ioat_dma_unmap(struct ioat_chan_common *chan, enum dma_ctrl_flags flags,
+		    size_t len, struct ioat_dma_descriptor *hw);
 #endif /* IOATDMA_H */

drivers/dma/ioat/dma_v2.h

+/*
+ * Copyright(c) 2004 - 2009 Intel Corporation. All rights reserved.
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License as published by the Free
+ * Software Foundation; either version 2 of the License, or (at your option)
+ * any later version.
+ *
+ * This program is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
+ * more details.
+ *
+ * You should have received a copy of the GNU General Public License along with
+ * this program; if not, write to the Free Software Foundation, Inc., 59
+ * Temple Place - Suite 330, Boston, MA  02111-1307, USA.
+ *
+ * The full GNU General Public License is included in this distribution in the
+ * file called COPYING.
+ */
+#ifndef IOATDMA_V2_H
+#define IOATDMA_V2_H
+
+#include <linux/dmaengine.h>
+#include "dma.h"
+#include "hw.h"
+
+
+extern int ioat_pending_level;
+
+/*
+ * workaround for IOAT ver.3.0 null descriptor issue
+ * (channel returns error when size is 0)
+ */
+#define NULL_DESC_BUFFER_SIZE 1
+
+#define IOAT_MAX_ORDER 16
+#define ioat_get_alloc_order() \
+	(min(ioat_ring_alloc_order, IOAT_MAX_ORDER))
+
+/* struct ioat2_dma_chan - ioat v2 / v3 channel attributes
+ * @base: common ioat channel parameters
+ * @xfercap_log; log2 of channel max transfer length (for fast division)
+ * @head: allocated index
+ * @issued: hardware notification point
+ * @tail: cleanup index
+ * @pending: lock free indicator for issued != head
+ * @dmacount: identical to 'head' except for occasionally resetting to zero
+ * @alloc_order: log2 of the number of allocated descriptors
+ * @ring: software ring buffer implementation of hardware ring
+ * @ring_lock: protects ring attributes
+ */
+struct ioat2_dma_chan {
+	struct ioat_chan_common base;
+	size_t xfercap_log;
+	u16 head;
+	u16 issued;
+	u16 tail;
+	u16 dmacount;
+	u16 alloc_order;
+	int pending;
+	struct ioat_ring_ent **ring;
+	spinlock_t ring_lock;
+};
+
+static inline struct ioat2_dma_chan *to_ioat2_chan(struct dma_chan *c)
+{
+	struct ioat_chan_common *chan = to_chan_common(c);
+
+	return container_of(chan, struct ioat2_dma_chan, base);
+}
+
+static inline u16 ioat2_ring_mask(struct ioat2_dma_chan *ioat)
+{
+	return (1 << ioat->alloc_order) - 1;
+}
+
+/* count of descriptors in flight with the engine */
+static inline u16 ioat2_ring_active(struct ioat2_dma_chan *ioat)
+{
+	return (ioat->head - ioat->tail) & ioat2_ring_mask(ioat);
+}
+
+/* count of descriptors pending submission to hardware */
+static inline u16 ioat2_ring_pending(struct ioat2_dma_chan *ioat)
+{
+	return (ioat->head - ioat->issued) & ioat2_ring_mask(ioat);
+}
+
+static inline u16 ioat2_ring_space(struct ioat2_dma_chan *ioat)
+{
+	u16 num_descs = ioat2_ring_mask(ioat) + 1;
+	u16 active = ioat2_ring_active(ioat);
+
+	BUG_ON(active > num_descs);
+
+	return num_descs - active;
+}
+
+/* assumes caller already checked space */
+static inline u16 ioat2_desc_alloc(struct ioat2_dma_chan *ioat, u16 len)
+{
+	ioat->head += len;
+	return ioat->head - len;
+}
+
+static inline u16 ioat2_xferlen_to_descs(struct ioat2_dma_chan *ioat, size_t len)
+{
+	u16 num_descs = len >> ioat->xfercap_log;
+
+	num_descs += !!(len & ((1 << ioat->xfercap_log) - 1));
+	return num_descs;
+}
+
+struct ioat_ring_ent {
+	struct ioat_dma_descriptor *hw;
+	struct dma_async_tx_descriptor txd;
+	size_t len;
+};
+
+static inline struct ioat_ring_ent *
+ioat2_get_ring_ent(struct ioat2_dma_chan *ioat, u16 idx)
+{
+	return ioat->ring[idx & ioat2_ring_mask(ioat)];
+}
+
+int ioat2_dma_probe(struct ioatdma_device *dev, int dca);
+int ioat3_dma_probe(struct ioatdma_device *dev, int dca);
+struct dca_provider *ioat2_dca_init(struct pci_dev *pdev, void __iomem *iobase);
+struct dca_provider *ioat3_dca_init(struct pci_dev *pdev, void __iomem *iobase);
+#endif /* IOATDMA_V2_H */

drivers/dma/ioat/pci.c

@@ -31,6 +31,7 @@
 #include <linux/interrupt.h>
 #include <linux/dca.h>
 #include "dma.h"
+#include "dma_v2.h"
 #include "registers.h"
 #include "hw.h"