dmaengine: reference counted unmap data

Hang a common 'unmap' object off of dma descriptors for the purpose of
providing a unified unmapping interface.  The lifetime of a mapping may
span multiple descriptors, so these unmap objects are reference counted
by related descriptor.

Cc: Vinod Koul <vinod.koul@intel.com>
Cc: Tomasz Figa <t.figa@samsung.com>
Cc: Dave Jiang <dave.jiang@intel.com>
[bzolnier: fix IS_ENABLED() check]
[bzolnier: fix release ordering in dmaengine_destroy_unmap_pool()]
[bzolnier: fix check for success in dmaengine_init_unmap_pool()]
[bzolnier: use mempool_free() instead of kmem_cache_free()]
[bzolnier: add missing unmap->len initializations]
[bzolnier: add __init tag to dmaengine_init_unmap_pool()]
Signed-off-by: Bartlomiej Zolnierkiewicz <b.zolnierkie@samsung.com>
Signed-off-by: Kyungmin Park <kyungmin.park@samsung.com>
[djbw: move DMAENGINE=n support to this patch for async_tx]
Signed-off-by: Dan Williams <dan.j.williams@intel.com>

2 files changed, 150 insertions, 9 deletions

diff --git a/drivers/dma/dmaengine.c b/drivers/dma/dmaengine.c
index bbc89df6bc56..e721a1caff7f 100644
--- a/drivers/dma/dmaengine.c
+++ b/drivers/dma/dmaengine.c
@@ -65,6 +65,7 @@
 #include <linux/acpi.h>
 #include <linux/acpi_dma.h>
 #include <linux/of_dma.h>
+#include <linux/mempool.h>
 
 static DEFINE_MUTEX(dma_list_mutex);
 static DEFINE_IDR(dma_idr);
@@ -901,6 +902,129 @@ void dma_async_device_unregister(struct dma_device *device)
 }
 EXPORT_SYMBOL(dma_async_device_unregister);
 
+struct dmaengine_unmap_pool {
+        struct kmem_cache *cache;
+        const char *name;
+        mempool_t *pool;
+        size_t size;
+};
+
+#define __UNMAP_POOL(x) { .size = x, .name = "dmaengine-unmap-" __stringify(x) }
+static struct dmaengine_unmap_pool unmap_pool[] = {
+        __UNMAP_POOL(2),
+        #if IS_ENABLED(CONFIG_ASYNC_TX_DMA)
+        __UNMAP_POOL(16),
+        __UNMAP_POOL(128),
+        __UNMAP_POOL(256),
+        #endif
+};
+
+static struct dmaengine_unmap_pool *__get_unmap_pool(int nr)
+{
+        int order = get_count_order(nr);
+
+        switch (order) {
+        case 0 ... 1:
+                return &unmap_pool[0];
+        case 2 ... 4:
+                return &unmap_pool[1];
+        case 5 ... 7:
+                return &unmap_pool[2];
+        case 8:
+                return &unmap_pool[3];
+        default:
+                BUG();
+                return NULL;
+        }
+}
+
+static void dmaengine_unmap(struct kref *kref)
+{
+        struct dmaengine_unmap_data *unmap = container_of(kref, typeof(*unmap), kref);
+        struct device *dev = unmap->dev;
+        int cnt, i;
+
+        cnt = unmap->to_cnt;
+        for (i = 0; i < cnt; i++)
+                dma_unmap_page(dev, unmap->addr[i], unmap->len,
+                               DMA_TO_DEVICE);
+        cnt += unmap->from_cnt;
+        for (; i < cnt; i++)
+                dma_unmap_page(dev, unmap->addr[i], unmap->len,
+                               DMA_FROM_DEVICE);
+        cnt += unmap->bidi_cnt;
+        for (; i < cnt; i++)
+                dma_unmap_page(dev, unmap->addr[i], unmap->len,
+                               DMA_BIDIRECTIONAL);
+        mempool_free(unmap, __get_unmap_pool(cnt)->pool);
+}
+
+void dmaengine_unmap_put(struct dmaengine_unmap_data *unmap)
+{
+        if (unmap)
+                kref_put(&unmap->kref, dmaengine_unmap);
+}
+EXPORT_SYMBOL_GPL(dmaengine_unmap_put);
+
+static void dmaengine_destroy_unmap_pool(void)
+{
+        int i;
+
+        for (i = 0; i < ARRAY_SIZE(unmap_pool); i++) {
+                struct dmaengine_unmap_pool *p = &unmap_pool[i];
+
+                if (p->pool)
+                        mempool_destroy(p->pool);
+                p->pool = NULL;
+                if (p->cache)
+                        kmem_cache_destroy(p->cache);
+                p->cache = NULL;
+        }
+}
+
+static int __init dmaengine_init_unmap_pool(void)
+{
+        int i;
+
+        for (i = 0; i < ARRAY_SIZE(unmap_pool); i++) {
+                struct dmaengine_unmap_pool *p = &unmap_pool[i];
+                size_t size;
+
+                size = sizeof(struct dmaengine_unmap_data) +
+                       sizeof(dma_addr_t) * p->size;
+
+                p->cache = kmem_cache_create(p->name, size, 0,
+                                             SLAB_HWCACHE_ALIGN, NULL);
+                if (!p->cache)
+                        break;
+                p->pool = mempool_create_slab_pool(1, p->cache);
+                if (!p->pool)
+                        break;
+        }
+
+        if (i == ARRAY_SIZE(unmap_pool))
+                return 0;
+
+        dmaengine_destroy_unmap_pool();
+        return -ENOMEM;
+}
+
+static struct dmaengine_unmap_data *
+dmaengine_get_unmap_data(struct device *dev, int nr, gfp_t flags)
+{
+        struct dmaengine_unmap_data *unmap;
+
+        unmap = mempool_alloc(__get_unmap_pool(nr)->pool, flags);
+        if (!unmap)
+                return NULL;
+
+        memset(unmap, 0, sizeof(*unmap));
+        kref_init(&unmap->kref);
+        unmap->dev = dev;
+
+        return unmap;
+}
+
 /**
  * dma_async_memcpy_pg_to_pg - offloaded copy from page to page
  * @chan: DMA channel to offload copy to
@@ -922,24 +1046,34 @@ dma_async_memcpy_pg_to_pg(struct dma_chan *chan, struct page *dest_pg,
 {
         struct dma_device *dev = chan->device;
         struct dma_async_tx_descriptor *tx;
-        dma_addr_t dma_dest, dma_src;
+        struct dmaengine_unmap_data *unmap;
         dma_cookie_t cookie;
         unsigned long flags;
 
-        dma_src = dma_map_page(dev->dev, src_pg, src_off, len, DMA_TO_DEVICE);
-        dma_dest = dma_map_page(dev->dev, dest_pg, dest_off, len,
-                                DMA_FROM_DEVICE);
-        flags = DMA_CTRL_ACK;
-        tx = dev->device_prep_dma_memcpy(chan, dma_dest, dma_src, len, flags);
+        unmap = dmaengine_get_unmap_data(dev->dev, 2, GFP_NOIO);
+        if (!unmap)
+                return -ENOMEM;
+
+        unmap->to_cnt = 1;
+        unmap->from_cnt = 1;
+        unmap->addr[0] = dma_map_page(dev->dev, src_pg, src_off, len,
+                                      DMA_TO_DEVICE);
+        unmap->addr[1] = dma_map_page(dev->dev, dest_pg, dest_off, len,
+                                      DMA_FROM_DEVICE);
+        unmap->len = len;
+        flags = DMA_CTRL_ACK | DMA_COMPL_SKIP_SRC_UNMAP |
+                DMA_COMPL_SKIP_DEST_UNMAP;
+        tx = dev->device_prep_dma_memcpy(chan, unmap->addr[1], unmap->addr[0],
+                                         len, flags);
 
         if (!tx) {
-                dma_unmap_page(dev->dev, dma_src, len, DMA_TO_DEVICE);
-                dma_unmap_page(dev->dev, dma_dest, len, DMA_FROM_DEVICE);
+                dmaengine_unmap_put(unmap);
                 return -ENOMEM;
         }
 
-        tx->callback = NULL;
+        dma_set_unmap(tx, unmap);
         cookie = tx->tx_submit(tx);
+        dmaengine_unmap_put(unmap);
 
         preempt_disable();
         __this_cpu_add(chan->local->bytes_transferred, len);
@@ -1069,6 +1203,10 @@ EXPORT_SYMBOL_GPL(dma_run_dependencies);