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

From: Rob Herring
Date: Thu Nov 18 2021 - 13:12:24 EST


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 <mpe@xxxxxxxxxxxxxx>
Cc: Benjamin Herrenschmidt <benh@xxxxxxxxxxxxxxxxxxx>
Cc: Paul Mackerras <paulus@xxxxxxxxx>
Cc: Frank Rowand <frowand.list@xxxxxxxxx>
Cc: linuxppc-dev@xxxxxxxxxxxxxxxx
Signed-off-by: Rob Herring <robh@xxxxxxxxxx>
---
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