hw/dma.c: Fix conversion of ioport_register* to MemoryRegion

The commit 5822993 introduced a 1-shift for
some offset in DMA emulation.

Before the previous commit, which converted ioport_register_* to
MemoryRegion, the DMA controller registered 8 ioports with the following
formula:
base + ((8 + i) << d->shift) where 0 <= i < 8
When an IO occured within a Memory Region, DMA callback receives an
offset relative to the start address. Here the start address is:
base + (8 << d->shift).
The offset should be: (i << d->shift). After the shift is reverted, the
offsets are 0..7 not 1..8.

Fixes LP#1089996.

Reported-by: Andreas Gustafsson <gson@gson.org>
Signed-off-by: Julien Grall <julien.grall@citrix.com>
Tested-by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Andreas Färber <afaerber@suse.de>

hw/dma.c

@@ -201,15 +201,15 @@ static void write_cont(void *opaque, hwaddr nport, uint64_t data,
 
     iport = (nport >> d->dshift) & 0x0f;
     switch (iport) {
-    case 0x01:                  /* command */
+    case 0x00:                  /* command */
         if ((data != 0) && (data & CMD_NOT_SUPPORTED)) {
             dolog("command %"PRIx64" not supported\n", data);
             return;
         }
         d->command = data;
         break;
 
-    case 0x02:
+    case 0x01:
         ichan = data & 3;
         if (data & 4) {
             d->status |= 1 << (ichan + 4);
@@ -221,15 +221,15 @@ static void write_cont(void *opaque, hwaddr nport, uint64_t data,
         DMA_run();
         break;
 
-    case 0x03:                  /* single mask */
+    case 0x02:                  /* single mask */
         if (data & 4)
             d->mask |= 1 << (data & 3);
         else
             d->mask &= ~(1 << (data & 3));
         DMA_run();
         break;
 
-    case 0x04:                  /* mode */
+    case 0x03:                  /* mode */
         {
             ichan = data & 3;
 #ifdef DEBUG_DMA
@@ -248,23 +248,23 @@ static void write_cont(void *opaque, hwaddr nport, uint64_t data,
             break;
         }
 
-    case 0x05:                  /* clear flip flop */
+    case 0x04:                  /* clear flip flop */
         d->flip_flop = 0;
         break;
 
-    case 0x06:                  /* reset */
+    case 0x05:                  /* reset */
         d->flip_flop = 0;
         d->mask = ~0;
         d->status = 0;
         d->command = 0;
         break;
 
-    case 0x07:                  /* clear mask for all channels */
+    case 0x06:                  /* clear mask for all channels */
         d->mask = 0;
         DMA_run();
         break;
 
-    case 0x08:                  /* write mask for all channels */
+    case 0x07:                  /* write mask for all channels */
         d->mask = data;
         DMA_run();
         break;
@@ -289,11 +289,11 @@ static uint64_t read_cont(void *opaque, hwaddr nport, unsigned size)
 
     iport = (nport >> d->dshift) & 0x0f;
     switch (iport) {
-    case 0x08:                  /* status */
+    case 0x00:                  /* status */
         val = d->status;
         d->status &= 0xf0;
         break;
-    case 0x0f:                  /* mask */
+    case 0x01:                  /* mask */
         val = d->mask;
         break;
     default:
@@ -468,7 +468,7 @@ void DMA_schedule(int nchan)
 static void dma_reset(void *opaque)
 {
     struct dma_cont *d = opaque;
-    write_cont(d, (0x06 << d->dshift), 0, 1);
+    write_cont(d, (0x05 << d->dshift), 0, 1);
 }
 
 static int dma_phony_handler (void *opaque, int nchan, int dma_pos, int dma_len)