[PATCH kvm-unit-tests 02/15] devicetree: introduce dt_get_initrd

[Andrew Jones <drjones@redhat.com>]

Allow DT users to find the initrd if one is passed on the
QEMU command line.

Signed-off-by: Andrew Jones <drjones@redhat.com>
---
 lib/devicetree.h | 10 ++++++++++
 lib/devicetree.c | 34 ++++++++++++++++++++++++++++++++++
 2 files changed, 44 insertions(+)

diff --git a/lib/devicetree.h b/lib/devicetree.h
index 9a4d910b6450..93c7ebc63bd8 100644
--- a/lib/devicetree.h
+++ b/lib/devicetree.h
@@ -220,6 +220,16 @@ extern int dt_get_bootargs(const char **bootargs);
 extern int dt_get_default_console_node(void);
 
 /*
+ * dt_get_initrd gets the physical address of the initrd and its
+ * size from /chosen
+ * returns
+ *  - zero on success
+ *  - a negative FDT_ERR_* value on failure, and @initrd will be
+ *    set to NULL and @size set to zero
+ */
+extern int dt_get_initrd(const char **initrd, u32 *size);
+
+/*
  * dt_get_memory_params gets the memory parameters from the /memory node(s)
  * storing each memory region ("address size" tuple) in consecutive entries
  * of @regs, up to @nr_regs
diff --git a/lib/devicetree.c b/lib/devicetree.c
index 509649b917cf..2b89178a109b 100644
--- a/lib/devicetree.c
+++ b/lib/devicetree.c
@@ -282,6 +282,40 @@ int dt_get_default_console_node(void)
 	return fdt_path_offset(fdt, prop->data);
 }
 
+int dt_get_initrd(const char **initrd, u32 *size)
+{
+	const struct fdt_property *prop;
+	const char *start, *end;
+	int node, len;
+	u32 *data;
+
+	*initrd = NULL;
+	*size = 0;
+
+	node = fdt_path_offset(fdt, "/chosen");
+	if (node < 0)
+		return node;
+
+	prop = fdt_get_property(fdt, node, "linux,initrd-start", &len);
+	if (!prop)
+		return len;
+	data = (u32 *)prop->data;
+	start = (const char *)(unsigned long)fdt32_to_cpu(*data);
+
+	prop = fdt_get_property(fdt, node, "linux,initrd-end", &len);
+	if (!prop) {
+		assert(len != -FDT_ERR_NOTFOUND);
+		return len;
+	}
+	data = (u32 *)prop->data;
+	end = (const char *)(unsigned long)fdt32_to_cpu(*data);
+
+	*initrd = start;
+	*size = (unsigned long)end - (unsigned long)start;
+
+	return 0;
+}
+
 int dt_init(const void *fdt_ptr)
 {
 	int ret;
-- 
2.9.3