[CELL] spufs: fix read and write for decr_status file

The decr_status in the LSCSA is valid only in the sequence of context
restore. Thus, it's nonsense to read and/or write it through spufs.

This patch changes decr_status node to access MFC_CNTL[Ds] in the CSA.
Signed-off-by: Masato Noguchi <Masato.Noguchi@jp.sony.com>
Signed-off-by: Jeremy Kerr <jk@ozlabs.org>
Signed-off-by: Arnd Bergmann <arnd.bergmann@de.ibm.com>

arch/powerpc/platforms/cell/spufs/file.c

@@ -1651,17 +1651,21 @@ DEFINE_SIMPLE_ATTRIBUTE(spufs_decr_ops, spufs_decr_get, spufs_decr_set,
 static void spufs_decr_status_set(void *data, u64 val)
 {
 	struct spu_context *ctx = data;
-	struct spu_lscsa *lscsa = ctx->csa.lscsa;
 	spu_acquire_saved(ctx);
-	lscsa->decr_status.slot[0] = (u32) val;
+	if (val)
+		ctx->csa.priv2.mfc_control_RW |= MFC_CNTL_DECREMENTER_RUNNING;
+	else
+		ctx->csa.priv2.mfc_control_RW &= ~MFC_CNTL_DECREMENTER_RUNNING;
 	spu_release_saved(ctx);
 }
 
 static u64 __spufs_decr_status_get(void *data)
 {
 	struct spu_context *ctx = data;
-	struct spu_lscsa *lscsa = ctx->csa.lscsa;
-	return lscsa->decr_status.slot[0];
+	if (ctx->csa.priv2.mfc_control_RW & MFC_CNTL_DECREMENTER_RUNNING)
+		return SPU_DECR_STATUS_RUNNING;
+	else
+		return 0;
 }
 
 static u64 spufs_decr_status_get(void *data)