[Qemu-devel] [PATCH 1/2] device_tree: Add qemu_devtree_setprop_sized_cells() utility function

[Peter Maydell]

We already have a qemu_devtree_setprop_cells() which sets a dtb
property to an array of cells whose values are specified by varargs.
However for the fairly common case of setting a property to a list
of addresses or of address,size pairs the number of cells used by
each element in the list depends on the parent's #address-cells
and #size-cells properties. To make this easier we provide an analogous
qemu_devtree_setprop_sized_cells() function which allows the number
of cells used by each element to be specified.

Signed-off-by: Peter Maydell <address@hidden>
---
 device_tree.c                |   48 ++++++++++++++++++++++++++++++++++++++++++
 include/sysemu/device_tree.h |   29 +++++++++++++++++++++++++
 2 files changed, 77 insertions(+)

diff --git a/device_tree.c b/device_tree.c
index 69be9da..15a081c 100644
--- a/device_tree.c
+++ b/device_tree.c
@@ -319,3 +319,51 @@ void qemu_devtree_dumpdtb(void *fdt, int size)
     }
 
 }
+
+int qemu_devtree_setprop_sized_cells(void *fdt, const char *node_path,
+                                     const char *property, ...)
+{
+    uint32_t *propcells;
+    uint32_t propsize = 0;
+    va_list ap;
+    uint32_t ncells;
+    uint64_t value;
+    int i, argnum;
+
+    va_start(ap, property);
+    for (;;) {
+        ncells = va_arg(ap, uint32_t);
+        if (!ncells) {
+            break;
+        }
+        assert(ncells < 3);
+        propsize += ncells;
+        value = va_arg(ap, uint64_t);
+    }
+    va_end(ap);
+
+    propcells = g_new0(uint32_t, propsize);
+
+    i = 0;
+    va_start(ap, property);
+    for (argnum = 1; ; argnum++) {
+        uint32_t hival;
+
+        ncells = va_arg(ap, uint32_t);
+        if (!ncells) {
+            break;
+        }
+        value = va_arg(ap, uint64_t);
+        hival = cpu_to_be32(value >> 32);
+        if (ncells > 1) {
+            propcells[i++] = hival;
+        } else if (hival != 0) {
+            return argnum;
+        }
+        propcells[i++] = cpu_to_be32(value);
+    }
+    va_end(ap);
+
+    return qemu_devtree_setprop(fdt, node_path, property, propcells,
+                                propsize * sizeof(uint32_t));
+}
diff --git a/include/sysemu/device_tree.h b/include/sysemu/device_tree.h
index f0b3f35..d7691f9 100644
--- a/include/sysemu/device_tree.h
+++ b/include/sysemu/device_tree.h
@@ -51,4 +51,33 @@ int qemu_devtree_add_subnode(void *fdt, const char *name);
 
 void qemu_devtree_dumpdtb(void *fdt, int size);
 
+/**
+ * qemu_devtree_setprop_sized_cells:
+ * @fdt: device tree blob
+ * @node_path: node to set property on
+ * @property: property to set
+ * @...: 0-terminated list of uint32_t number-of-cells, uint64_t value pairs
+ *
+ * Set the specified property on the specified node in the device tree
+ * to be an array of cells. The values of the cells are specified via
+ * the varargs list, which alternates between "number of cells used by
+ * this value" and "value" (terminated when number-of-cells is zero).
+ * number-of-cells must be either 1 or 2 (other values will assert()).
+ *
+ * This function is useful because device tree nodes often have cell arrays
+ * which are either lists of addresses or lists of address,size tuples, but
+ * the number of cells used for each element vary depending on the
+ * #address-cells and #size-cells properties of their parent node.
+ * If you know all your cell elements are one cell wide you can use the
+ * simpler qemu_devtree_setprop_cells().
+ *
+ * Return value: 0 on success, <0 if setting the property failed,
+ * n (for n>0) if value n wouldn't fit in the required number of cells.
+ * (This slightly odd convention is for the benefit of callers who might
+ * wish to print different error messages depending on which value
+ * was too large to fit, since values might be user-specified.)
+ */
+int qemu_devtree_setprop_sized_cells(void *fdt, const char *node_path,
+                                     const char *property, ...);
+
 #endif /* __DEVICE_TREE_H__ */
-- 
1.7.9.5