diff --git a/dma-helpers.c b/dma-helpers.c
index c29ea6d..5f19a85 100644
--- a/dma-helpers.c
+++ b/dma-helpers.c
@@ -42,7 +42,7 @@ typedef struct {
     BlockDriverAIOCB *acb;
     QEMUSGList *sg;
     uint64_t sector_num;
-    bool to_dev;
+    DMADirection dir;
     bool in_cancel;
     int sg_cur_index;
     dma_addr_t sg_cur_byte;
@@ -76,7 +76,8 @@ static void dma_bdrv_unmap(DMAAIOCB *dbs)
 
     for (i = 0; i < dbs->iov.niov; ++i) {
         cpu_physical_memory_unmap(dbs->iov.iov[i].iov_base,
-                                  dbs->iov.iov[i].iov_len, !dbs->to_dev,
+                                  dbs->iov.iov[i].iov_len,
+                                  dbs->dir != DMA_DIRECTION_TO_DEVICE,
                                   dbs->iov.iov[i].iov_len);
     }
     qemu_iovec_reset(&dbs->iov);
@@ -123,7 +124,8 @@ static void dma_bdrv_cb(void *opaque, int ret)
     while (dbs->sg_cur_index < dbs->sg->nsg) {
         cur_addr = dbs->sg->sg[dbs->sg_cur_index].base + dbs->sg_cur_byte;
         cur_len = dbs->sg->sg[dbs->sg_cur_index].len - dbs->sg_cur_byte;
-        mem = cpu_physical_memory_map(cur_addr, &cur_len, !dbs->to_dev);
+        mem = cpu_physical_memory_map(cur_addr, &cur_len,
+                                      dbs->dir != DMA_DIRECTION_TO_DEVICE);
         if (!mem)
             break;
         qemu_iovec_add(&dbs->iov, mem, cur_len);
@@ -170,11 +172,11 @@ static AIOPool dma_aio_pool = {
 BlockDriverAIOCB *dma_bdrv_io(
     BlockDriverState *bs, QEMUSGList *sg, uint64_t sector_num,
     DMAIOFunc *io_func, BlockDriverCompletionFunc *cb,
-    void *opaque, bool to_dev)
+    void *opaque, DMADirection dir)
 {
     DMAAIOCB *dbs = qemu_aio_get(&dma_aio_pool, bs, cb, opaque);
 
-    trace_dma_bdrv_io(dbs, bs, sector_num, to_dev);
+    trace_dma_bdrv_io(dbs, bs, sector_num, (dir == DMA_DIRECTION_TO_DEVICE));
 
     dbs->acb = NULL;
     dbs->bs = bs;
@@ -182,7 +184,7 @@ BlockDriverAIOCB *dma_bdrv_io(
     dbs->sector_num = sector_num;
     dbs->sg_cur_index = 0;
     dbs->sg_cur_byte = 0;
-    dbs->to_dev = to_dev;
+    dbs->dir = dir;
     dbs->io_func = io_func;
     dbs->bh = NULL;
     qemu_iovec_init(&dbs->iov, sg->nsg);
@@ -195,14 +197,16 @@ BlockDriverAIOCB *dma_bdrv_read(BlockDriverState *bs,
                                 QEMUSGList *sg, uint64_t sector,
                                 void (*cb)(void *opaque, int ret), void *opaque)
 {
-    return dma_bdrv_io(bs, sg, sector, bdrv_aio_readv, cb, opaque, false);
+    return dma_bdrv_io(bs, sg, sector, bdrv_aio_readv, cb, opaque,
+                       DMA_DIRECTION_FROM_DEVICE);
 }
 
 BlockDriverAIOCB *dma_bdrv_write(BlockDriverState *bs,
                                  QEMUSGList *sg, uint64_t sector,
                                  void (*cb)(void *opaque, int ret), void *opaque)
 {
-    return dma_bdrv_io(bs, sg, sector, bdrv_aio_writev, cb, opaque, true);
+    return dma_bdrv_io(bs, sg, sector, bdrv_aio_writev, cb, opaque,
+                       DMA_DIRECTION_TO_DEVICE);
 }
 
 
diff --git a/dma.h b/dma.h
index 20e86d2..05ac325 100644
--- a/dma.h
+++ b/dma.h
@@ -17,6 +17,11 @@
 
 typedef struct ScatterGatherEntry ScatterGatherEntry;
 
+typedef enum {
+    DMA_DIRECTION_TO_DEVICE = 0,
+    DMA_DIRECTION_FROM_DEVICE = 1,
+} DMADirection;
+
 struct QEMUSGList {
     ScatterGatherEntry *sg;
     int nsg;
@@ -29,11 +34,6 @@ typedef target_phys_addr_t dma_addr_t;
 
 #define DMA_ADDR_FMT TARGET_FMT_plx
 
-typedef enum {
-    DMA_DIRECTION_TO_DEVICE = 0,
-    DMA_DIRECTION_FROM_DEVICE = 1,
-} DMADirection;
-
 struct ScatterGatherEntry {
     dma_addr_t base;
     dma_addr_t len;
@@ -51,7 +51,7 @@ typedef BlockDriverAIOCB *DMAIOFunc(BlockDriverState *bs, int64_t sector_num,
 BlockDriverAIOCB *dma_bdrv_io(BlockDriverState *bs,
                               QEMUSGList *sg, uint64_t sector_num,
                               DMAIOFunc *io_func, BlockDriverCompletionFunc *cb,
-                              void *opaque, bool to_dev);
+                              void *opaque, DMADirection dir);
 BlockDriverAIOCB *dma_bdrv_read(BlockDriverState *bs,
                                 QEMUSGList *sg, uint64_t sector,
                                 BlockDriverCompletionFunc *cb, void *opaque);
diff --git a/hw/ide/core.c b/hw/ide/core.c
index 4d568ac..43da841 100644
--- a/hw/ide/core.c
+++ b/hw/ide/core.c
@@ -604,7 +604,8 @@ void ide_dma_cb(void *opaque, int ret)
         break;
     case IDE_DMA_TRIM:
         s->bus->dma->aiocb = dma_bdrv_io(s->bs, &s->sg, sector_num,
-                                         ide_issue_trim, ide_dma_cb, s, true);
+                                         ide_issue_trim, ide_dma_cb, s,
+                                         DMA_DIRECTION_TO_DEVICE);
         break;
     }
     return;
diff --git a/hw/ide/macio.c b/hw/ide/macio.c
index a4df244..7b38d9e 100644
--- a/hw/ide/macio.c
+++ b/hw/ide/macio.c
@@ -149,7 +149,8 @@ static void pmac_ide_transfer_cb(void *opaque, int ret)
         break;
     case IDE_DMA_TRIM:
         m->aiocb = dma_bdrv_io(s->bs, &s->sg, sector_num,
-                               ide_issue_trim, pmac_ide_transfer_cb, s, true);
+                               ide_issue_trim, pmac_ide_transfer_cb, s,
+                               DMA_DIRECTION_TO_DEVICE);
         break;
     }
     return;
