[RFC PATCH v2 4/9] add generic dmabounce support
Albert Herranz
albert_herranz at yahoo.es
Mon Mar 1 01:07:57 EST 2010
This patch makes part of the ARM dmabounce code available to other
architectures as a generic API.
See included kernel-doc annotations for the actual API implemented.
An architecture can opt-in for generic dmabounce support by defining
HAVE_DMABOUNCE.
This support will be used later to address DMA memory access restrictions
on the Nintendo Wii video game console.
Signed-off-by: Albert Herranz <albert_herranz at yahoo.es>
---
arch/Kconfig | 3 +
include/linux/dmabounce.h | 77 +++++++++
lib/Kconfig | 10 ++
lib/Makefile | 2 +
lib/dmabounce.c | 395 +++++++++++++++++++++++++++++++++++++++++++++
5 files changed, 487 insertions(+), 0 deletions(-)
create mode 100644 include/linux/dmabounce.h
create mode 100644 lib/dmabounce.c
diff --git a/arch/Kconfig b/arch/Kconfig
index 9d055b4..98ff26d 100644
--- a/arch/Kconfig
+++ b/arch/Kconfig
@@ -130,6 +130,9 @@ config HAVE_CLK
config HAVE_DMA_API_DEBUG
bool
+config HAVE_DMABOUNCE
+ bool
+
config HAVE_DEFAULT_NO_SPIN_MUTEXES
bool
diff --git a/include/linux/dmabounce.h b/include/linux/dmabounce.h
new file mode 100644
index 0000000..d60dc04
--- /dev/null
+++ b/include/linux/dmabounce.h
@@ -0,0 +1,77 @@
+#ifndef _LINUX_DMABOUNCE_H
+#define _LINUX_DMABOUNCE_H
+
+/* FIXME remove later when arch/arm/common/dmabounce.c is updated */
+#ifndef CONFIG_ARM
+
+#ifdef CONFIG_DMABOUNCE
+
+#include <linux/dmapool.h>
+#include <linux/dma-mapping.h>
+#include <linux/list.h>
+#include <linux/types.h>
+#include <linux/device.h>
+
+struct dmabounce_info;
+
+#ifdef CONFIG_DMABOUNCE_STATS
+struct dmabounce_stats {
+ unsigned long total_allocs;
+ unsigned long map_op_count;
+ unsigned long bounce_count;
+};
+extern struct dmabounce_stats *dmabounce_get_stats(struct dmabounce_info *);
+#define DMABOUNCE_DO_STATS(i, X) do { dmabounce_get_stats(i)->X ; } while (0)
+#else
+#define DMABOUNCE_DO_STATS(i, X) do { } while (0)
+#endif /* CONFIG_DMABOUNCE_STATS */
+
+struct dmabounce_pool {
+ unsigned long size;
+ struct dma_pool *pool;
+#ifdef CONFIG_DMABOUNCE_STATS
+ unsigned long allocs;
+#endif
+};
+
+struct dmabounce_buffer {
+ struct list_head node;
+
+ /* original buffer */
+ void *buf;
+ size_t size;
+ enum dma_data_direction dir;
+
+ /* bounced buffer */
+ void *bounce_buf;
+ dma_addr_t bounce_buf_dma;
+
+ struct dmabounce_pool *pool;
+};
+
+extern struct dmabounce_buffer *
+dmabounce_alloc_buffer(struct dmabounce_info *info,
+ void *buf, size_t size, enum dma_data_direction dir,
+ gfp_t gfp);
+extern void dmabounce_free_buffer(struct dmabounce_info *info,
+ struct dmabounce_buffer *bb);
+extern struct dmabounce_buffer *
+dmabounce_find_buffer(struct dmabounce_info *info, dma_addr_t bounce_buf_dma,
+ size_t size, enum dma_data_direction dir);
+
+extern struct dmabounce_info *
+dmabounce_info_alloc(struct device *dev,
+ size_t small_buffer_size, size_t large_buffer_size,
+ size_t align, size_t boundary);
+extern void dmabounce_info_free(struct dmabounce_info *info);
+
+extern int dmabounce_info_register(struct device *dev,
+ struct dmabounce_info *info);
+extern void dmabounce_info_unregister(struct device *dev);
+
+#endif /* CONFIG_DMABOUNCE */
+
+/* FIXME remove later when arch/arm/common/dmabounce.c is updated */
+#endif /* !CONFIG_ARM */
+
+#endif /* _LINUX_DMABOUNCE_H */
diff --git a/lib/Kconfig b/lib/Kconfig
index 97b136f..b53b7dc 100644
--- a/lib/Kconfig
+++ b/lib/Kconfig
@@ -207,4 +207,14 @@ config GENERIC_ATOMIC64
config LRU_CACHE
tristate
+config DMABOUNCE
+ bool
+ depends on HAVE_DMABOUNCE
+ select ZONE_DMA if ARM
+ default y
+
+config DMABOUNCE_STATS
+ bool "Track dmabounce statistics"
+ depends on DMABOUNCE
+
endmenu
diff --git a/lib/Makefile b/lib/Makefile
index 3b0b4a6..097c2ed 100644
--- a/lib/Makefile
+++ b/lib/Makefile
@@ -100,6 +100,8 @@ obj-$(CONFIG_GENERIC_CSUM) += checksum.o
obj-$(CONFIG_GENERIC_ATOMIC64) += atomic64.o
+obj-$(CONFIG_DMABOUNCE) += dmabounce.o
+
hostprogs-y := gen_crc32table
clean-files := crc32table.h
diff --git a/lib/dmabounce.c b/lib/dmabounce.c
new file mode 100644
index 0000000..620d314
--- /dev/null
+++ b/lib/dmabounce.c
@@ -0,0 +1,395 @@
+/*
+ * lib/dmabounce.c
+ *
+ * Generic DMA bounce buffer functions.
+ * Copyright (C) 2010 Albert Herranz <albert_herranz at yahoo.es>
+ *
+ * Based on arch/arm/common/dmabounce.c
+ *
+ * Original version by Brad Parker (brad at heeltoe.com)
+ * Re-written by Christopher Hoover <ch at murgatroid.com>
+ * Made generic by Deepak Saxena <dsaxena at plexity.net>
+ *
+ * Copyright (C) 2002 Hewlett Packard Company.
+ * Copyright (C) 2004 MontaVista Software, Inc.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * version 2 as published by the Free Software Foundation.
+ */
+
+/* FIXME remove later when arch/arm/common/dmabounce.c is updated */
+#ifndef CONFIG_ARM
+
+#define DRV_MODULE_NAME "dmabounce"
+#define DRV_DESCRIPTION "Generic DMA bounce buffer functions"
+#define DRV_AUTHOR "Christopher Hoover <ch at hpl.hp.com>, " \
+ "Deepak Saxena <dsaxena at plexity.net>, " \
+ "Albert Herranz <albert_herranz at yahoo.es>"
+
+#define pr_fmt(fmt) DRV_MODULE_NAME ": " fmt
+#include <linux/kernel.h>
+#include <linux/dma-mapping.h>
+#include <linux/dmapool.h>
+#include <linux/dmabounce.h>
+
+
+struct dmabounce_info {
+ struct device *dev;
+ struct list_head bounce_buffers;
+
+#ifdef CONFIG_DMABOUNCE_STATS
+ struct dmabounce_stats stats;
+ int attr_res;
+#endif
+ struct dmabounce_pool small;
+ struct dmabounce_pool large;
+
+ rwlock_t lock;
+};
+
+#ifdef CONFIG_DMABOUNCE_STATS
+struct dmabounce_stats *dmabounce_get_stats(struct dmabounce_info *info)
+{
+ return &info->stats;
+}
+
+static ssize_t dmabounce_show(struct device *dev,
+ struct device_attribute *attr, char *buf)
+{
+ struct dmabounce_info *info = dev->archdata.dmabounce;
+ return sprintf(buf, "%lu %lu %lu %lu %lu %lu\n",
+ info->small.allocs,
+ info->large.allocs,
+ info->stats.total_allocs -
+ info->small.allocs - info->large.allocs,
+ info->stats.total_allocs,
+ info->stats.map_op_count,
+ info->stats.bounce_count);
+}
+
+static DEVICE_ATTR(dmabounce_stats, 0400, dmabounce_show, NULL);
+#endif /* CONFIG_DMABOUNCE_STATS */
+
+/**
+ * dmabounce_alloc_buffer() - try to allocate a coherent DMA bounce buffer
+ * @info: This dmabounce_info.
+ * @buf: Original buffer virtual address.
+ * @size: Original buffer length.
+ * @dir: Direction of DMA transfer for this buffer.
+ * @gfp: Flags used for memory allocations.
+ *
+ * Use this function to allocate a coherent buffer of size @size associated
+ * to a dmabounce_info structure @info.
+ * The allocation will be performed using the @gfp allocation flags.
+ *
+ * The coherent buffer can be used later to bounce data from/to the
+ * corresponding normal buffer @buf with the specified direction @dir.
+ *
+ * If the buffer cannot be allocated the function returns NULL.
+ * Otherwise, the allocated buffer is returned.
+ */
+struct dmabounce_buffer *
+dmabounce_alloc_buffer(struct dmabounce_info *info,
+ void *buf, size_t size, enum dma_data_direction dir,
+ gfp_t gfp)
+{
+ struct device *dev = info->dev;
+ struct dmabounce_pool *pool = NULL;
+ struct dmabounce_buffer *bb;
+ unsigned long flags;
+
+ dev_dbg(dev, "%s(buf=%p, size=%d, dir=%d)\n", __func__, buf, size, dir);
+
+ if (size <= info->small.size)
+ pool = &info->small;
+ else if (size <= info->large.size)
+ pool = &info->large;
+
+ bb = kzalloc(sizeof(*bb), gfp);
+ if (!bb) {
+ dev_err(dev, "%s: kmalloc failed\n", __func__);
+ goto out;
+ }
+
+ if (pool) {
+ bb->bounce_buf = dma_pool_alloc(pool->pool, gfp,
+ &bb->bounce_buf_dma);
+ } else {
+ bb->bounce_buf = dma_alloc_coherent(dev, size,
+ &bb->bounce_buf_dma, gfp);
+ }
+
+ if (!bb->bounce_buf) {
+ dev_err(dev, "%s: error allocating DMA memory (size=%d)\n",
+ __func__, size);
+ kfree(bb);
+ bb = NULL;
+ goto out;
+ }
+
+#ifdef CONFIG_DMABOUNCE_STATS
+ if (pool)
+ pool->allocs++;
+#endif
+ DMABOUNCE_DO_STATS(info, total_allocs++);
+
+ bb->buf = buf;
+ bb->size = size;
+ bb->dir = dir;
+ bb->pool = pool;
+
+ write_lock_irqsave(&info->lock, flags);
+ list_add(&bb->node, &info->bounce_buffers);
+ write_unlock_irqrestore(&info->lock, flags);
+out:
+ return bb;
+}
+EXPORT_SYMBOL(dmabounce_alloc_buffer);
+
+/**
+ * dmabounce_free_buffer() - free a coherent DMA bounce buffer
+ * @info: This dmabounce_info.
+ * @bb: The coherent DMA bounce buffer to free.
+ *
+ * Free a previously allocated coherent DMA bounce buffer @bb from its
+ * associated dmabounce_info structure @info.
+ *
+ * The coherent DMA bounce buffer @bb must have been previously allocated
+ * using dmabounce_alloc_buffer().
+ */
+void
+dmabounce_free_buffer(struct dmabounce_info *info, struct dmabounce_buffer *bb)
+{
+ unsigned long flags;
+
+ dev_dbg(info->dev, "%s(buf=%p)\n", __func__, bb->buf);
+
+ write_lock_irqsave(&info->lock, flags);
+ list_del(&bb->node);
+ write_unlock_irqrestore(&info->lock, flags);
+
+ if (bb->pool)
+ dma_pool_free(bb->pool->pool, bb->bounce_buf,
+ bb->bounce_buf_dma);
+ else {
+ dma_free_coherent(info->dev, bb->size, bb->bounce_buf,
+ bb->bounce_buf_dma);
+ }
+
+ kfree(bb);
+}
+EXPORT_SYMBOL(dmabounce_free_buffer);
+
+/**
+ * dmabounce_find_buffer() - locate an existing coherent DMA bounce buffer
+ * @info: This dmabounce_info.
+ * @bounce_buf_dma: DMA handle for the bounce buffer to find.
+ * @size: Size of the bounce buffer to find.
+ * @dir: Direction of DMA transfer for the buffer to find.
+ *
+ * Finds a previously allocated coherent DMA bounce buffer associated
+ * to a dmabounce_info structure @info.
+ *
+ * The coherent DMA bounce buffer searched must have the given
+ * @bounce_buf_dma DMA handle, @size size and DMA direction @dir.
+ * If @size is zero, the searched buffer can have any size.
+ *
+ * If no matching coherent DMA bounce buffer is found the function returns
+ * NULL. Otherwise, the matching buffer is returned.
+ */
+struct dmabounce_buffer *
+dmabounce_find_buffer(struct dmabounce_info *info, dma_addr_t bounce_buf_dma,
+ size_t size, enum dma_data_direction dir)
+{
+ struct dmabounce_buffer *bb, *needle = NULL;
+ unsigned long flags;
+
+ read_lock_irqsave(&info->lock, flags);
+
+ list_for_each_entry(bb, &info->bounce_buffers, node) {
+ if (bb->bounce_buf_dma == bounce_buf_dma) {
+ /* we should get a perfect match here */
+ BUG_ON((size && bb->size != size) || bb->dir != dir);
+
+ needle = bb;
+ break;
+ }
+ }
+
+ read_unlock_irqrestore(&info->lock, flags);
+ return needle;
+}
+EXPORT_SYMBOL(dmabounce_find_buffer);
+
+static int dmabounce_init_pool(struct dmabounce_pool *pool,
+ struct device *dev, const char *name,
+ size_t size, size_t align, size_t boundary)
+{
+ pool->size = size;
+#ifdef CONFIG_DMABOUNCE_STATS
+ pool->allocs = 0;
+#endif
+ pool->pool = dma_pool_create(name, dev, size, align, boundary);
+
+ return pool->pool ? 0 : -ENOMEM;
+}
+
+/**
+ * dmabounce_info_alloc() - allocate a dmabounce_info structure
+ * @dev: Device for which coherent memory allocations are done.
+ * @small_buffer_size: Buffer size for allocations from the small pool.
+ * @large_buffer_size: Buffer size for allocations from the large pool.
+ * @align: Alignment for pool based allocations.
+ * @boundary: Boundary for pool based allocations.
+ *
+ * Use this function to allocate a dmabounce_info structure.
+ * A dmabounce_info structure can be used to manage a set of related
+ * coherent DMA bounce buffers.
+ *
+ * Memory for the coherent DMA bounce buffers will be allocated for the
+ * specified device @dev.
+ * If @small_buffer_size or @large_buffer_size are non-zero, allocations
+ * will be tried from the closest associated DMA pool which has a size
+ * greater or equal than the specified @size size. Allocations from DMA
+ * pools will honor the alignment and boundary crossing restrictions
+ * specified in @align and @boundary.
+ * Otherwise, allocations will be performed from non-pool coherent memory.
+ *
+ * If the dmabounce_info structure cannot be allocated the function
+ * returns NULL. Otherwise, the allocated dmabounce_info structure is returned.
+ */
+struct dmabounce_info *
+dmabounce_info_alloc(struct device *dev,
+ size_t small_buffer_size, size_t large_buffer_size,
+ size_t align, size_t boundary)
+{
+ struct dmabounce_info *info;
+ int error;
+
+ info = kzalloc(sizeof(*info), GFP_KERNEL);
+ if (!info) {
+ dev_err(dev, "%s: allocation error\n", __func__);
+ goto out;
+ }
+
+ if (small_buffer_size) {
+ error = dmabounce_init_pool(&info->small, dev,
+ "small_dmabounce_pool",
+ small_buffer_size, align, boundary);
+ if (error) {
+ dev_err(dev, "error %d allocating DMA pool for %zu"
+ " byte objects\n", error, small_buffer_size);
+ goto err_alloc_small;
+ }
+ }
+
+ if (large_buffer_size) {
+ error = dmabounce_init_pool(&info->large, dev,
+ "large_dmabounce_pool",
+ large_buffer_size, align, boundary);
+ if (error) {
+ dev_err(dev, "error %d allocating DMA pool for %zu"
+ " byte objects\n", error, large_buffer_size);
+ goto err_alloc_large;
+ }
+ }
+
+ info->dev = dev;
+ INIT_LIST_HEAD(&info->bounce_buffers);
+ rwlock_init(&info->lock);
+
+ DMABOUNCE_DO_STATS(info, total_allocs = 0);
+ DMABOUNCE_DO_STATS(info, map_op_count = 0);
+ DMABOUNCE_DO_STATS(info, bounce_count = 0);
+ goto out;
+
+err_alloc_large:
+ dma_pool_destroy(info->small.pool);
+err_alloc_small:
+ kfree(info);
+ info = NULL;
+out:
+ return info;
+}
+EXPORT_SYMBOL(dmabounce_info_alloc);
+
+/**
+ * dmabounce_info_free() - free a dmabounce_info
+ * @info: This dmabounce_info.
+ *
+ * Free a previously allocated dmabounce_info structure @info.
+ *
+ * The dmabounce_info structure @info must have been previously allocated
+ * using dmabounce_info_alloc().
+ */
+void dmabounce_info_free(struct dmabounce_info *info)
+{
+ if (!list_empty(&info->bounce_buffers)) {
+ dev_err(info->dev, "freeing dmabounce with pending buffers!\n");
+ BUG();
+ }
+
+ if (info->small.pool)
+ dma_pool_destroy(info->small.pool);
+ if (info->large.pool)
+ dma_pool_destroy(info->large.pool);
+
+ kfree(info);
+}
+EXPORT_SYMBOL(dmabounce_info_free);
+
+/**
+ * dmabounce_info_register() - register a dmabounce_info for a device
+ * @dev: Device for which the dmabounce_info is registered.
+ * @info: dmabounce_info to register.
+ *
+ * Use this function to register a given dmabounce_info @info into a
+ * device @dev.
+ *
+ * A device can only have one dmabounce_info registered with.
+ * The same dmabounce_info may be registered for many devices.
+ */
+int dmabounce_info_register(struct device *dev, struct dmabounce_info *info)
+{
+ if (dev->archdata.dmabounce)
+ return -EBUSY;
+
+ dev->archdata.dmabounce = info;
+
+#ifdef CONFIG_DMABOUNCE_STATS
+ info->attr_res = device_create_file(dev, &dev_attr_dmabounce_stats);
+#endif
+
+ dev_info(dev, pr_fmt("device registered\n"));
+ return 0;
+}
+EXPORT_SYMBOL(dmabounce_info_register);
+
+/**
+ * dmabounce_info_unregister() - unregister the dmabounce_info from a device
+ * @dev: Device for which the dmabounce_info is unregistered.
+ *
+ * Use this function to unregister a previously registered dmabounce_info
+ * from a device @dev.
+ */
+void dmabounce_info_unregister(struct device *dev)
+{
+#ifdef CONFIG_DMABOUNCE_STATS
+ struct dmabounce_info *info = dev->archdata.dmabounce;
+
+ if (info && info->attr_res == 0)
+ device_remove_file(dev, &dev_attr_dmabounce_stats);
+#endif
+ dev->archdata.dmabounce = NULL;
+
+ dev_info(dev, pr_fmt("device unregistered\n"));
+}
+EXPORT_SYMBOL(dmabounce_info_unregister);
+
+MODULE_AUTHOR(DRV_AUTHOR);
+MODULE_DESCRIPTION(DRV_DESCRIPTION);
+MODULE_LICENSE("GPL");
+
+/* FIXME remove later when arch/arm/common/dmabounce.c is updated */
+#endif /* !CONFIG_ARM */
--
1.6.3.3
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