[Qemu-devel] [PATCH v4 1/2] ARM: Allow boards to provide an fdt blob

[Peter Maydell <peter.maydell@linaro.org>]

From: John Rigby <john.rigby@linaro.org>

If no fdt is provided on command line and the new field
get_dtb in struct arm_boot_info is set then call it to
get a device tree blob.

Signed-off-by: John Rigby <john.rigby@linaro.org>
[PMM: minor tweaks and cleanup]
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
---
 hw/arm/boot.c        |   32 ++++++++++++++++++++------------
 include/hw/arm/arm.h |    7 +++++++
 2 files changed, 27 insertions(+), 12 deletions(-)

diff --git a/hw/arm/boot.c b/hw/arm/boot.c
index 2cbeefd..9d790b7 100644
--- a/hw/arm/boot.c
+++ b/hw/arm/boot.c
@@ -228,23 +228,31 @@ static void set_kernel_args_old(const struct arm_boot_info *info)
 static int load_dtb(hwaddr addr, const struct arm_boot_info *binfo)
 {
     void *fdt = NULL;
-    char *filename;
     int size, rc;
     uint32_t acells, scells;
 
-    filename = qemu_find_file(QEMU_FILE_TYPE_BIOS, binfo->dtb_filename);
-    if (!filename) {
-        fprintf(stderr, "Couldn't open dtb file %s\n", binfo->dtb_filename);
-        goto fail;
-    }
+    if (binfo->dtb_filename) {
+        char *filename;
+        filename = qemu_find_file(QEMU_FILE_TYPE_BIOS, binfo->dtb_filename);
+        if (!filename) {
+            fprintf(stderr, "Couldn't open dtb file %s\n", binfo->dtb_filename);
+            goto fail;
+        }
 
-    fdt = load_device_tree(filename, &size);
-    if (!fdt) {
-        fprintf(stderr, "Couldn't open dtb file %s\n", filename);
+        fdt = load_device_tree(filename, &size);
+        if (!fdt) {
+            fprintf(stderr, "Couldn't open dtb file %s\n", filename);
+            g_free(filename);
+            goto fail;
+        }
         g_free(filename);
-        goto fail;
+    } else if (binfo->get_dtb) {
+        fdt = binfo->get_dtb(binfo, &size);
+        if (!fdt) {
+            fprintf(stderr, "Board was unable to create a dtb blob\n");
+            goto fail;
+        }
     }
-    g_free(filename);
 
     acells = qemu_devtree_getprop_cell(fdt, "/", "#address-cells");
     scells = qemu_devtree_getprop_cell(fdt, "/", "#size-cells");
@@ -436,7 +444,7 @@ void arm_load_kernel(ARMCPU *cpu, struct arm_boot_info *info)
         /* for device tree boot, we pass the DTB directly in r2. Otherwise
          * we point to the kernel args.
          */
-        if (info->dtb_filename) {
+        if (info->dtb_filename || info->get_dtb) {
             /* Place the DTB after the initrd in memory. Note that some
              * kernels will trash anything in the 4K page the initrd
              * ends in, so make sure the DTB isn't caught up in that.
diff --git a/include/hw/arm/arm.h b/include/hw/arm/arm.h
index bae87c6..4e51a9e 100644
--- a/include/hw/arm/arm.h
+++ b/include/hw/arm/arm.h
@@ -55,6 +55,13 @@ struct arm_boot_info {
                                  const struct arm_boot_info *info);
     void (*secondary_cpu_reset_hook)(ARMCPU *cpu,
                                      const struct arm_boot_info *info);
+    /* if a board is able to create a dtb without a dtb file then it
+     * sets get_dtb. This will only be used if no dtb file is provided
+     * by the user. On success, sets *size to the length of the created
+     * dtb, and returns a pointer to it. (The caller must free this memory
+     * with g_free() when it has finished with it.) On failure, returns NULL.
+     */
+    void *(*get_dtb)(const struct arm_boot_info *info, int *size);
     /* if a board needs to be able to modify a device tree provided by
      * the user it should implement this hook.
      */
-- 
1.7.9.5