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[Qemu-devel] [PATCH v2] device_tree: Add support for reading device tree
From: |
Peter Maydell |
Subject: |
[Qemu-devel] [PATCH v2] device_tree: Add support for reading device tree properties |
Date: |
Tue, 10 Jul 2012 14:32:16 +0100 |
Add support for reading device tree properties (both generic
and single-cell ones) to QEMU's convenience wrapper layer.
Signed-off-by: Peter Maydell <address@hidden>
---
Here's a v2:
* added qemu_devtree_get_one_cell_from_prop() which reads a single cell from
a property which is an array of cells
* NB that qemu_devtree_getprop() isn't implemented in terms of this because
that would give worse error handling.
I still think that having this new function is misguided:
* nobody's using it
* it breaks the current model where functions at the qemu_devtree and
libfdt levels deal only with entire properties and do not look inside
them to operate on only part of the property value
But here's a patch so we can argue about something concrete.
device_tree.c | 49 +++++++++++++++++++++++++++++++++++++++++++++++++
device_tree.h | 6 ++++++
2 files changed, 55 insertions(+), 0 deletions(-)
diff --git a/device_tree.c b/device_tree.c
index b366fdd..3a8ff13 100644
--- a/device_tree.c
+++ b/device_tree.c
@@ -178,6 +178,55 @@ int qemu_devtree_setprop_string(void *fdt, const char
*node_path,
return r;
}
+const void *qemu_devtree_getprop(void *fdt, const char *node_path,
+ const char *property, int *lenp)
+{
+ int len;
+ const void *r;
+ if (!lenp) {
+ lenp = &len;
+ }
+ r = fdt_getprop(fdt, findnode_nofail(fdt, node_path), property, lenp);
+ if (!r) {
+ fprintf(stderr, "%s: Couldn't get %s/%s: %s\n", __func__,
+ node_path, property, fdt_strerror(*lenp));
+ exit(1);
+ }
+ return r;
+}
+
+uint32_t qemu_devtree_get_one_cell_from_prop(void *fdt, const char *node_path,
+ const char *property, int idx)
+{
+ int len;
+ const uint32_t *p = qemu_devtree_getprop(fdt, node_path, property, &len);
+ if (len % 4 != 0) {
+ fprintf(stderr, "%s: %s/%s not multiple of 4 bytes long "
+ "(not cells?)\n",
+ __func__, node_path, property);
+ exit(1);
+ }
+ if (len < (idx + 1) * 4) {
+ fprintf(stderr, "%s: %s/%s wrong length to contain %d cells\n",
+ __func__, node_path, property, idx + 1);
+ exit(1);
+ }
+ return be32_to_cpu(p[idx]);
+}
+
+uint32_t qemu_devtree_getprop_cell(void *fdt, const char *node_path,
+ const char *property)
+{
+ int len;
+ const uint32_t *p = qemu_devtree_getprop(fdt, node_path, property, &len);
+ if (len != 4) {
+ fprintf(stderr, "%s: %s/%s not 4 bytes long (not a cell?)\n",
+ __func__, node_path, property);
+ exit(1);
+ }
+ return be32_to_cpu(*p);
+}
+
uint32_t qemu_devtree_get_phandle(void *fdt, const char *path)
{
uint32_t r;
diff --git a/device_tree.h b/device_tree.h
index 2244270..86669ea 100644
--- a/device_tree.h
+++ b/device_tree.h
@@ -28,6 +28,12 @@ int qemu_devtree_setprop_string(void *fdt, const char
*node_path,
int qemu_devtree_setprop_phandle(void *fdt, const char *node_path,
const char *property,
const char *target_node_path);
+const void *qemu_devtree_getprop(void *fdt, const char *node_path,
+ const char *property, int *lenp);
+uint32_t qemu_devtree_getprop_cell(void *fdt, const char *node_path,
+ const char *property);
+uint32_t qemu_devtree_get_one_cell_from_prop(void *fdt, const char *node_path,
+ const char *property, int idx);
uint32_t qemu_devtree_get_phandle(void *fdt, const char *path);
uint32_t qemu_devtree_alloc_phandle(void *fdt);
int qemu_devtree_nop_node(void *fdt, const char *node_path);
--
1.7.1
- [Qemu-devel] [PATCH v2] device_tree: Add support for reading device tree properties,
Peter Maydell <=