device_tree: qemu_fdt_getprop_cell converted to use the error API

This patch aligns the prototype with qemu_fdt_getprop. The caller
can choose whether the function self-asserts on error (passing
&error_fatal as Error ** argument, corresponding to the legacy behavior),
or behaves differently such as simply output a message.

In this later case the caller can use the new lenp parameter to interpret
the error if any.

Signed-off-by: Eric Auger <eric.auger@linaro.org>
Reviewed-by: Peter Crosthwaite <crosthwaite.peter@gmail.com>
Signed-off-by: Alex Williamson <alex.williamson@redhat.com>

device_tree.c

@@ -350,15 +350,22 @@ const void *qemu_fdt_getprop(void *fdt, const char *node_path,
 }
 
 uint32_t qemu_fdt_getprop_cell(void *fdt, const char *node_path,
-                               const char *property)
+                               const char *property, int *lenp, Error **errp)
 {
     int len;
-    const uint32_t *p = qemu_fdt_getprop(fdt, node_path, property, &len,
-                                         &error_fatal);
-    if (len != 4) {
-        error_report("%s: %s/%s not 4 bytes long (not a cell?)",
-                     __func__, node_path, property);
-        exit(1);
+    const uint32_t *p;
+
+    if (!lenp) {
+        lenp = &len;
+    }
+    p = qemu_fdt_getprop(fdt, node_path, property, lenp, errp);
+    if (!p) {
+        return 0;
+    } else if (*lenp != 4) {
+        error_setg(errp, "%s: %s/%s not 4 bytes long (not a cell?)",
+                   __func__, node_path, property);
+        *lenp = -EINVAL;
+        return 0;
     }
     return be32_to_cpu(*p);
 }

hw/arm/boot.c

@@ -437,8 +437,10 @@ static int load_dtb(hwaddr addr, const struct arm_boot_info *binfo,
         return 0;
     }
 
-    acells = qemu_fdt_getprop_cell(fdt, "/", "#address-cells");
-    scells = qemu_fdt_getprop_cell(fdt, "/", "#size-cells");
+    acells = qemu_fdt_getprop_cell(fdt, "/", "#address-cells",
+                                   NULL, &error_fatal);
+    scells = qemu_fdt_getprop_cell(fdt, "/", "#size-cells",
+                                   NULL, &error_fatal);
     if (acells == 0 || scells == 0) {
         fprintf(stderr, "dtb file invalid (#address-cells or #size-cells 0)\n");
         goto fail;

hw/arm/vexpress.c

@@ -478,8 +478,10 @@ static void vexpress_modify_dtb(const struct arm_boot_info *info, void *fdt)
     uint32_t acells, scells, intc;
     const VEDBoardInfo *daughterboard = (const VEDBoardInfo *)info;
 
-    acells = qemu_fdt_getprop_cell(fdt, "/", "#address-cells");
-    scells = qemu_fdt_getprop_cell(fdt, "/", "#size-cells");
+    acells = qemu_fdt_getprop_cell(fdt, "/", "#address-cells",
+                                   NULL, &error_fatal);
+    scells = qemu_fdt_getprop_cell(fdt, "/", "#size-cells",
+                                   NULL, &error_fatal);
     intc = find_int_controller(fdt);
     if (!intc) {
         /* Not fatal, we just won't provide virtio. This will

include/sysemu/device_tree.h

@@ -67,8 +67,20 @@ int qemu_fdt_setprop_phandle(void *fdt, const char *node_path,
 const void *qemu_fdt_getprop(void *fdt, const char *node_path,
                              const char *property, int *lenp,
                              Error **errp);
+/**
+ * qemu_fdt_getprop_cell: retrieve the value of a given 4 byte property
+ * @fdt: pointer to the device tree blob
+ * @node_path: node path
+ * @property: name of the property to find
+ * @lenp: fdt error if any or -EINVAL if the property size is different from
+ *        4 bytes, or 4 (expected length of the property) upon success.
+ * @errp: handle to an error object
+ *
+ * returns the property value on success
+ */
 uint32_t qemu_fdt_getprop_cell(void *fdt, const char *node_path,
-                               const char *property);
+                               const char *property, int *lenp,
+                               Error **errp);
 uint32_t qemu_fdt_get_phandle(void *fdt, const char *path);
 uint32_t qemu_fdt_alloc_phandle(void *fdt);
 int qemu_fdt_nop_node(void *fdt, const char *node_path);