[PATCH 2/3] of/fdt: Rework early_init_dt_scan_root() to call directly

[Rob Herring]

Use of the of_scan_flat_dt() function predates libfdt and is discouraged
as libfdt provides a nicer set of APIs. Rework early_init_dt_scan_root()
to be called directly and use libfdt.

Cc: Michael Ellerman <m...@ellerman.id.au>
Cc: Benjamin Herrenschmidt <b...@kernel.crashing.org>
Cc: Paul Mackerras <pau...@samba.org>
Cc: Frank Rowand <frowand.l...@gmail.com>
Cc: linuxppc-dev@lists.ozlabs.org
Signed-off-by: Rob Herring <r...@kernel.org>
---
 arch/powerpc/kernel/prom.c |  4 ++--
 drivers/of/fdt.c           | 14 +++++++-------
 include/linux/of_fdt.h     |  3 +--
 3 files changed, 10 insertions(+), 11 deletions(-)

diff --git a/arch/powerpc/kernel/prom.c b/arch/powerpc/kernel/prom.c
index c6c398ccd98a..6e1a106f02eb 100644
--- a/arch/powerpc/kernel/prom.c
+++ b/arch/powerpc/kernel/prom.c
@@ -748,7 +748,7 @@ void __init early_init_devtree(void *params)
        of_scan_flat_dt(early_init_dt_scan_chosen_ppc, boot_command_line);
 
        /* Scan memory nodes and rebuild MEMBLOCKs */
-       of_scan_flat_dt(early_init_dt_scan_root, NULL);
+       early_init_dt_scan_root();
        of_scan_flat_dt(early_init_dt_scan_memory_ppc, NULL);
 
        parse_early_param();
@@ -857,7 +857,7 @@ void __init early_get_first_memblock_info(void *params, 
phys_addr_t *size)
         * mess the memblock.
         */
        add_mem_to_memblock = 0;
-       of_scan_flat_dt(early_init_dt_scan_root, NULL);
+       early_init_dt_scan_root();
        of_scan_flat_dt(early_init_dt_scan_memory_ppc, NULL);
        add_mem_to_memblock = 1;
 
diff --git a/drivers/of/fdt.c b/drivers/of/fdt.c
index 1f1705f76263..5e216555fe4f 100644
--- a/drivers/of/fdt.c
+++ b/drivers/of/fdt.c
@@ -1042,13 +1042,14 @@ int __init early_init_dt_scan_chosen_stdout(void)
 /*
  * early_init_dt_scan_root - fetch the top level address and size cells
  */
-int __init early_init_dt_scan_root(unsigned long node, const char *uname,
-                                  int depth, void *data)
+int __init early_init_dt_scan_root(void)
 {
        const __be32 *prop;
+       const void *fdt = initial_boot_params;
+       int node = fdt_path_offset(fdt, "/");
 
-       if (depth != 0)
-               return 0;
+       if (node < 0)
+               return -ENODEV;
 
        dt_root_size_cells = OF_ROOT_NODE_SIZE_CELLS_DEFAULT;
        dt_root_addr_cells = OF_ROOT_NODE_ADDR_CELLS_DEFAULT;
@@ -1063,8 +1064,7 @@ int __init early_init_dt_scan_root(unsigned long node, 
const char *uname,
                dt_root_addr_cells = be32_to_cpup(prop);
        pr_debug("dt_root_addr_cells = %x\n", dt_root_addr_cells);
 
-       /* break now */
-       return 1;
+       return 0;
 }
 
 u64 __init dt_mem_next_cell(int s, const __be32 **cellp)
@@ -1263,7 +1263,7 @@ void __init early_init_dt_scan_nodes(void)
        int rc;
 
        /* Initialize {size,address}-cells info */
-       of_scan_flat_dt(early_init_dt_scan_root, NULL);
+       early_init_dt_scan_root();
 
        /* Retrieve various information from the /chosen node */
        rc = early_init_dt_scan_chosen(boot_command_line);
diff --git a/include/linux/of_fdt.h b/include/linux/of_fdt.h
index 654722235df6..df3d31926c3c 100644
--- a/include/linux/of_fdt.h
+++ b/include/linux/of_fdt.h
@@ -68,8 +68,7 @@ extern void early_init_dt_add_memory_arch(u64 base, u64 size);
 extern u64 dt_mem_next_cell(int s, const __be32 **cellp);
 
 /* Early flat tree scan hooks */
-extern int early_init_dt_scan_root(unsigned long node, const char *uname,
-                                  int depth, void *data);
+extern int early_init_dt_scan_root(void);
 
 extern bool early_init_dt_scan(void *params);
 extern bool early_init_dt_verify(void *params);
-- 
2.32.0