hw/nand: Support multiple reads following READ STATUS

After receiving READ STATUS command all subsequent IO reads should return
the status register value until another command is issued.

Signed-off-by: Juha Riihimäki <juha.riihimaki@nokia.com>
[Riku Voipio: Fixes and restructuring patchset]
Signed-off-by: Riku Voipio <riku.voipio@iki.fi>
[Peter Maydell: More fixes and cleanups for upstream submission]
Signed-off-by:  Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Andrzej Zaborowski <andrew.zaborowski@intel.com>

hw/nand.c

diff --git a/hw/nand.c b/hw/nand.c
index 4d1dff1..1eefe28 100644
--- a/hw/nand.c
+++ b/hw/nand.c
@@ -496,9 +496,14 @@
     for (offset = s->buswidth; offset--;) {
         x |= s->ioaddr[offset] << (offset << 3);
     }
-    s->addr   += s->buswidth;
-    s->ioaddr += s->buswidth;
-    s->iolen  -= s->buswidth;
+    /* after receiving READ STATUS command all subsequent reads will
+     * return the status register value until another command is issued
+     */
+    if (s->cmd != NAND_CMD_READSTATUS) {
+        s->addr   += s->buswidth;
+        s->ioaddr += s->buswidth;
+        s->iolen  -= s->buswidth;
+    }
     return x;
 }