powerpc/pseries/iommu: Move window-removing part of remove_ddw into remove_dma_window

Move the window-removing part of remove_ddw into a new function
(remove_dma_window), so it can be used to remove other DMA windows.

It's useful for removing DMA windows that don't create DIRECT64_PROPNAME
property, like the default DMA window from the device, which uses
"ibm,dma-window".
Signed-off-by: Leonardo Bras <leobras.c@gmail.com>
Tested-by: David Dai <zdai@linux.vnet.ibm.com>
Reviewed-by: Alexey Kardashevskiy <aik@ozlabs.ru>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20200805030455.123024-4-leobras.c@gmail.com

arch/powerpc/platforms/pseries/iommu.c

@@ -781,25 +781,14 @@ static int __init disable_ddw_setup(char *str)
 
 early_param("disable_ddw", disable_ddw_setup);
 
-static void remove_ddw(struct device_node *np, bool remove_prop)
+static void remove_dma_window(struct device_node *np, u32 *ddw_avail,
+			      struct property *win)
 {
 	struct dynamic_dma_window_prop *dwp;
-	struct property *win64;
-	u32 ddw_avail[DDW_APPLICABLE_SIZE];
 	u64 liobn;
-	int ret = 0;
-
-	ret = of_property_read_u32_array(np, "ibm,ddw-applicable",
-					 &ddw_avail[0], DDW_APPLICABLE_SIZE);
-
-	win64 = of_find_property(np, DIRECT64_PROPNAME, NULL);
-	if (!win64)
-		return;
-
-	if (ret || win64->length < sizeof(*dwp))
-		goto delprop;
+	int ret;
 
-	dwp = win64->value;
+	dwp = win->value;
 	liobn = (u64)be32_to_cpu(dwp->liobn);
 
 	/* clear the whole window, note the arg is in kernel pages */
@@ -821,10 +810,30 @@ static void remove_ddw(struct device_node *np, bool remove_prop)
 		pr_debug("%pOF: successfully removed direct window: rtas returned "
 			"%d to ibm,remove-pe-dma-window(%x) %llx\n",
 			np, ret, ddw_avail[DDW_REMOVE_PE_DMA_WIN], liobn);
+}
+
+static void remove_ddw(struct device_node *np, bool remove_prop)
+{
+	struct property *win;
+	u32 ddw_avail[DDW_APPLICABLE_SIZE];
+	int ret = 0;
+
+	ret = of_property_read_u32_array(np, "ibm,ddw-applicable",
+					 &ddw_avail[0], DDW_APPLICABLE_SIZE);
+	if (ret)
+		return;
+
+	win = of_find_property(np, DIRECT64_PROPNAME, NULL);
+	if (!win)
+		return;
+
+	if (win->length >= sizeof(struct dynamic_dma_window_prop))
+		remove_dma_window(np, ddw_avail, win);
+
+	if (!remove_prop)
+		return;
 
-delprop:
-	if (remove_prop)
-		ret = of_remove_property(np, win64);
+	ret = of_remove_property(np, win);
 	if (ret)
 		pr_warn("%pOF: failed to remove direct window property: %d\n",
 			np, ret);