[PATCH 0/3] of/fdt: Rework early FDT scanning functions

[PATCH 0/3] of/fdt: Rework early FDT scanning functions

[Rob Herring]

The early FDT scanning functions use of_scan_flat_dt() which implements 
its own node walking method. This function predates libfdt and is an 
unnecessary indirection. This series reworks 
early_init_dt_scan_chosen(), early_init_dt_scan_root(), and 
early_init_dt_scan_memory() to be called directly and use libfdt calls.

Ultimately, I want to remove of_scan_flat_dt(). Most of the remaining 
of_scan_flat_dt() users are in powerpc.

Rob


Rob Herring (3):
  of/fdt: Rework early_init_dt_scan_chosen() to call directly
  of/fdt: Rework early_init_dt_scan_root() to call directly
  of/fdt: Rework early_init_dt_scan_memory() to call directly

 arch/mips/ralink/of.c                |  16 +---
 arch/powerpc/kernel/prom.c           |  22 ++---
 arch/powerpc/mm/nohash/kaslr_booke.c |   4 +-
 drivers/of/fdt.c                     | 121 ++++++++++++++-------------
 include/linux/of_fdt.h               |   9 +-
 5 files changed, 79 insertions(+), 93 deletions(-)

-- 
2.32.0

[PATCH 1/3] of/fdt: Rework early_init_dt_scan_chosen() 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_chosen() to be called directly and use libfdt.

Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Frank Rowand <frowand.list@gmail.com>
Cc: linuxppc-dev@lists.ozlabs.org
Signed-off-by: Rob Herring <robh@kernel.org>
---
 arch/powerpc/kernel/prom.c           |  2 +-
 arch/powerpc/mm/nohash/kaslr_booke.c |  4 +--
 drivers/of/fdt.c                     | 39 ++++++++++++++--------------
 include/linux/of_fdt.h               |  3 +--
 4 files changed, 22 insertions(+), 26 deletions(-)

diff --git a/arch/powerpc/kernel/prom.c b/arch/powerpc/kernel/prom.c
index 2e67588f6f6e..c6c398ccd98a 100644
--- a/arch/powerpc/kernel/prom.c
+++ b/arch/powerpc/kernel/prom.c
@@ -402,7 +402,7 @@ static int __init early_init_dt_scan_chosen_ppc(unsigned long node,
 	const unsigned long *lprop; /* All these set by kernel, so no need to convert endian */
 
 	/* Use common scan routine to determine if this is the chosen node */
-	if (early_init_dt_scan_chosen(node, uname, depth, data) == 0)
+	if (early_init_dt_scan_chosen(data) < 0)
 		return 0;
 
 #ifdef CONFIG_PPC64
diff --git a/arch/powerpc/mm/nohash/kaslr_booke.c b/arch/powerpc/mm/nohash/kaslr_booke.c
index 8fc49b1b4a91..90debe19ab4c 100644
--- a/arch/powerpc/mm/nohash/kaslr_booke.c
+++ b/arch/powerpc/mm/nohash/kaslr_booke.c
@@ -44,9 +44,7 @@ struct regions __initdata regions;
 
 static __init void kaslr_get_cmdline(void *fdt)
 {
-	int node = fdt_path_offset(fdt, "/chosen");
-
-	early_init_dt_scan_chosen(node, "chosen", 1, boot_command_line);
+	early_init_dt_scan_chosen(boot_command_line);
 }
 
 static unsigned long __init rotate_xor(unsigned long hash, const void *area,
diff --git a/drivers/of/fdt.c b/drivers/of/fdt.c
index bdca35284ceb..1f1705f76263 100644
--- a/drivers/of/fdt.c
+++ b/drivers/of/fdt.c
@@ -1124,18 +1124,18 @@ int __init early_init_dt_scan_memory(unsigned long node, const char *uname,
 	return 0;
 }
 
-int __init early_init_dt_scan_chosen(unsigned long node, const char *uname,
-				     int depth, void *data)
+int __init early_init_dt_scan_chosen(char *cmdline)
 {
-	int l;
+	int l, node;
 	const char *p;
 	const void *rng_seed;
+	const void *fdt = initial_boot_params;
 
-	pr_debug("search \"chosen\", depth: %d, uname: %s\n", depth, uname);
-
-	if (depth != 1 || !data ||
-	    (strcmp(uname, "chosen") != 0 && strcmp(uname, "chosen@0") != 0))
-		return 0;
+	node = fdt_path_offset(fdt, "/chosen");
+	if (node < 0)
+		node = fdt_path_offset(fdt, "/chosen@0");
+	if (node < 0)
+		return -ENOENT;
 
 	early_init_dt_check_for_initrd(node);
 	early_init_dt_check_for_elfcorehdr(node);
@@ -1144,7 +1144,7 @@ int __init early_init_dt_scan_chosen(unsigned long node, const char *uname,
 	/* Retrieve command line */
 	p = of_get_flat_dt_prop(node, "bootargs", &l);
 	if (p != NULL && l > 0)
-		strlcpy(data, p, min(l, COMMAND_LINE_SIZE));
+		strlcpy(cmdline, p, min(l, COMMAND_LINE_SIZE));
 
 	/*
 	 * CONFIG_CMDLINE is meant to be a default in case nothing else
@@ -1153,18 +1153,18 @@ int __init early_init_dt_scan_chosen(unsigned long node, const char *uname,
 	 */
 #ifdef CONFIG_CMDLINE
 #if defined(CONFIG_CMDLINE_EXTEND)
-	strlcat(data, " ", COMMAND_LINE_SIZE);
-	strlcat(data, CONFIG_CMDLINE, COMMAND_LINE_SIZE);
+	strlcat(cmdline, " ", COMMAND_LINE_SIZE);
+	strlcat(cmdline, CONFIG_CMDLINE, COMMAND_LINE_SIZE);
 #elif defined(CONFIG_CMDLINE_FORCE)
-	strlcpy(data, CONFIG_CMDLINE, COMMAND_LINE_SIZE);
+	strlcpy(cmdline, CONFIG_CMDLINE, COMMAND_LINE_SIZE);
 #else
 	/* No arguments from boot loader, use kernel's  cmdl*/
-	if (!((char *)data)[0])
-		strlcpy(data, CONFIG_CMDLINE, COMMAND_LINE_SIZE);
+	if (!((char *)cmdline)[0])
+		strlcpy(cmdline, CONFIG_CMDLINE, COMMAND_LINE_SIZE);
 #endif
 #endif /* CONFIG_CMDLINE */
 
-	pr_debug("Command line is: %s\n", (char *)data);
+	pr_debug("Command line is: %s\n", (char *)cmdline);
 
 	rng_seed = of_get_flat_dt_prop(node, "rng-seed", &l);
 	if (rng_seed && l > 0) {
@@ -1178,8 +1178,7 @@ int __init early_init_dt_scan_chosen(unsigned long node, const char *uname,
 				fdt_totalsize(initial_boot_params));
 	}
 
-	/* break now */
-	return 1;
+	return 0;
 }
 
 #ifndef MIN_MEMBLOCK_ADDR
@@ -1261,14 +1260,14 @@ bool __init early_init_dt_verify(void *params)
 
 void __init early_init_dt_scan_nodes(void)
 {
-	int rc = 0;
+	int rc;
 
 	/* Initialize {size,address}-cells info */
 	of_scan_flat_dt(early_init_dt_scan_root, NULL);
 
 	/* Retrieve various information from the /chosen node */
-	rc = of_scan_flat_dt(early_init_dt_scan_chosen, boot_command_line);
-	if (!rc)
+	rc = early_init_dt_scan_chosen(boot_command_line);
+	if (rc)
 		pr_warn("No chosen node found, continuing without\n");
 
 	/* Setup memory, calling early_init_dt_add_memory_arch */
diff --git a/include/linux/of_fdt.h b/include/linux/of_fdt.h
index cf48983d3c86..654722235df6 100644
--- a/include/linux/of_fdt.h
+++ b/include/linux/of_fdt.h
@@ -58,8 +58,7 @@ extern int of_flat_dt_is_compatible(unsigned long node, const char *name);
 extern unsigned long of_get_flat_dt_root(void);
 extern uint32_t of_get_flat_dt_phandle(unsigned long node);
 
-extern int early_init_dt_scan_chosen(unsigned long node, const char *uname,
-				     int depth, void *data);
+extern int early_init_dt_scan_chosen(char *cmdline);
 extern int early_init_dt_scan_memory(unsigned long node, const char *uname,
 				     int depth, void *data);
 extern int early_init_dt_scan_chosen_stdout(void);
-- 
2.32.0

Re: [PATCH 1/3] of/fdt: Rework early_init_dt_scan_chosen() to call directly

[Frank Rowand]

On 11/18/21 1:12 PM, Rob Herring wrote:
> 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_chosen() to be called directly and use libfdt.
> 
> Cc: Michael Ellerman <mpe@ellerman.id.au>
> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
> Cc: Paul Mackerras <paulus@samba.org>
> Cc: Frank Rowand <frowand.list@gmail.com>
> Cc: linuxppc-dev@lists.ozlabs.org
> Signed-off-by: Rob Herring <robh@kernel.org>
> ---
>  arch/powerpc/kernel/prom.c           |  2 +-
>  arch/powerpc/mm/nohash/kaslr_booke.c |  4 +--
>  drivers/of/fdt.c                     | 39 ++++++++++++++--------------
>  include/linux/of_fdt.h               |  3 +--
>  4 files changed, 22 insertions(+), 26 deletions(-)
> 
> diff --git a/arch/powerpc/kernel/prom.c b/arch/powerpc/kernel/prom.c
> index 2e67588f6f6e..c6c398ccd98a 100644
> --- a/arch/powerpc/kernel/prom.c
> +++ b/arch/powerpc/kernel/prom.c
> @@ -402,7 +402,7 @@ static int __init early_init_dt_scan_chosen_ppc(unsigned long node,
>  	const unsigned long *lprop; /* All these set by kernel, so no need to convert endian */
>  
>  	/* Use common scan routine to determine if this is the chosen node */
> -	if (early_init_dt_scan_chosen(node, uname, depth, data) == 0)
> +	if (early_init_dt_scan_chosen(data) < 0)
>  		return 0;
>  
>  #ifdef CONFIG_PPC64
> diff --git a/arch/powerpc/mm/nohash/kaslr_booke.c b/arch/powerpc/mm/nohash/kaslr_booke.c
> index 8fc49b1b4a91..90debe19ab4c 100644
> --- a/arch/powerpc/mm/nohash/kaslr_booke.c
> +++ b/arch/powerpc/mm/nohash/kaslr_booke.c
> @@ -44,9 +44,7 @@ struct regions __initdata regions;
>  
>  static __init void kaslr_get_cmdline(void *fdt)
>  {
> -	int node = fdt_path_offset(fdt, "/chosen");
> -
> -	early_init_dt_scan_chosen(node, "chosen", 1, boot_command_line);
> +	early_init_dt_scan_chosen(boot_command_line);
>  }
>  
>  static unsigned long __init rotate_xor(unsigned long hash, const void *area,
> diff --git a/drivers/of/fdt.c b/drivers/of/fdt.c
> index bdca35284ceb..1f1705f76263 100644
> --- a/drivers/of/fdt.c
> +++ b/drivers/of/fdt.c
> @@ -1124,18 +1124,18 @@ int __init early_init_dt_scan_memory(unsigned long node, const char *uname,
>  	return 0;
>  }
>  
> -int __init early_init_dt_scan_chosen(unsigned long node, const char *uname,
> -				     int depth, void *data)
> +int __init early_init_dt_scan_chosen(char *cmdline)
>  {
> -	int l;
> +	int l, node;
>  	const char *p;
>  	const void *rng_seed;
> +	const void *fdt = initial_boot_params;
>  
> -	pr_debug("search \"chosen\", depth: %d, uname: %s\n", depth, uname);
> -
> -	if (depth != 1 || !data ||
> -	    (strcmp(uname, "chosen") != 0 && strcmp(uname, "chosen@0") != 0))
> -		return 0;
> +	node = fdt_path_offset(fdt, "/chosen");
> +	if (node < 0)
> +		node = fdt_path_offset(fdt, "/chosen@0");
> +	if (node < 0)
> +		return -ENOENT;
>  
>  	early_init_dt_check_for_initrd(node);
>  	early_init_dt_check_for_elfcorehdr(node);
> @@ -1144,7 +1144,7 @@ int __init early_init_dt_scan_chosen(unsigned long node, const char *uname,
>  	/* Retrieve command line */
>  	p = of_get_flat_dt_prop(node, "bootargs", &l);
>  	if (p != NULL && l > 0)
> -		strlcpy(data, p, min(l, COMMAND_LINE_SIZE));
> +		strlcpy(cmdline, p, min(l, COMMAND_LINE_SIZE));
>  
>  	/*
>  	 * CONFIG_CMDLINE is meant to be a default in case nothing else
> @@ -1153,18 +1153,18 @@ int __init early_init_dt_scan_chosen(unsigned long node, const char *uname,
>  	 */
>  #ifdef CONFIG_CMDLINE
>  #if defined(CONFIG_CMDLINE_EXTEND)
> -	strlcat(data, " ", COMMAND_LINE_SIZE);
> -	strlcat(data, CONFIG_CMDLINE, COMMAND_LINE_SIZE);
> +	strlcat(cmdline, " ", COMMAND_LINE_SIZE);
> +	strlcat(cmdline, CONFIG_CMDLINE, COMMAND_LINE_SIZE);
>  #elif defined(CONFIG_CMDLINE_FORCE)
> -	strlcpy(data, CONFIG_CMDLINE, COMMAND_LINE_SIZE);
> +	strlcpy(cmdline, CONFIG_CMDLINE, COMMAND_LINE_SIZE);
>  #else
>  	/* No arguments from boot loader, use kernel's  cmdl*/
> -	if (!((char *)data)[0])
> -		strlcpy(data, CONFIG_CMDLINE, COMMAND_LINE_SIZE);
> +	if (!((char *)cmdline)[0])
> +		strlcpy(cmdline, CONFIG_CMDLINE, COMMAND_LINE_SIZE);
>  #endif
>  #endif /* CONFIG_CMDLINE */
>  
> -	pr_debug("Command line is: %s\n", (char *)data);
> +	pr_debug("Command line is: %s\n", (char *)cmdline);
>  
>  	rng_seed = of_get_flat_dt_prop(node, "rng-seed", &l);
>  	if (rng_seed && l > 0) {
> @@ -1178,8 +1178,7 @@ int __init early_init_dt_scan_chosen(unsigned long node, const char *uname,
>  				fdt_totalsize(initial_boot_params));
>  	}
>  
> -	/* break now */
> -	return 1;
> +	return 0;
>  }
>  
>  #ifndef MIN_MEMBLOCK_ADDR
> @@ -1261,14 +1260,14 @@ bool __init early_init_dt_verify(void *params)
>  
>  void __init early_init_dt_scan_nodes(void)
>  {
> -	int rc = 0;
> +	int rc;
>  
>  	/* Initialize {size,address}-cells info */
>  	of_scan_flat_dt(early_init_dt_scan_root, NULL);
>  
>  	/* Retrieve various information from the /chosen node */
> -	rc = of_scan_flat_dt(early_init_dt_scan_chosen, boot_command_line);
> -	if (!rc)
> +	rc = early_init_dt_scan_chosen(boot_command_line);
> +	if (rc)
>  		pr_warn("No chosen node found, continuing without\n");
>  
>  	/* Setup memory, calling early_init_dt_add_memory_arch */
> diff --git a/include/linux/of_fdt.h b/include/linux/of_fdt.h
> index cf48983d3c86..654722235df6 100644
> --- a/include/linux/of_fdt.h
> +++ b/include/linux/of_fdt.h
> @@ -58,8 +58,7 @@ extern int of_flat_dt_is_compatible(unsigned long node, const char *name);
>  extern unsigned long of_get_flat_dt_root(void);
>  extern uint32_t of_get_flat_dt_phandle(unsigned long node);
>  
> -extern int early_init_dt_scan_chosen(unsigned long node, const char *uname,
> -				     int depth, void *data);
> +extern int early_init_dt_scan_chosen(char *cmdline);
>  extern int early_init_dt_scan_memory(unsigned long node, const char *uname,
>  				     int depth, void *data);
>  extern int early_init_dt_scan_chosen_stdout(void);
> 

patch 1/3

Reviewed-by: Frank Rowand <frank.rowand@sony.com>

[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 <mpe@ellerman.id.au>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Frank Rowand <frowand.list@gmail.com>
Cc: linuxppc-dev@lists.ozlabs.org
Signed-off-by: Rob Herring <robh@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

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

[Frank Rowand]

On 11/18/21 1:12 PM, Rob Herring wrote:
> 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@ellerman.id.au>
> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
> Cc: Paul Mackerras <paulus@samba.org>
> Cc: Frank Rowand <frowand.list@gmail.com>
> Cc: linuxppc-dev@lists.ozlabs.org
> Signed-off-by: Rob Herring <robh@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);
> 

Reviewed-by: Frank Rowand <frank.rowand@sony.com>

[PATCH 3/3] of/fdt: Rework early_init_dt_scan_memory() 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_memory() to be called directly and use libfdt.

Cc: John Crispin <john@phrozen.org>
Cc: Thomas Bogendoerfer <tsbogend@alpha.franken.de>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Frank Rowand <frowand.list@gmail.com>
Cc: linux-mips@vger.kernel.org
Cc: linuxppc-dev@lists.ozlabs.org
Signed-off-by: Rob Herring <robh@kernel.org>
---
 arch/mips/ralink/of.c      | 16 ++-------
 arch/powerpc/kernel/prom.c | 16 ++++-----
 drivers/of/fdt.c           | 68 ++++++++++++++++++++------------------
 include/linux/of_fdt.h     |  3 +-
 4 files changed, 47 insertions(+), 56 deletions(-)

diff --git a/arch/mips/ralink/of.c b/arch/mips/ralink/of.c
index 0135376c5de5..e1d79523343a 100644
--- a/arch/mips/ralink/of.c
+++ b/arch/mips/ralink/of.c
@@ -53,17 +53,6 @@ void __init device_tree_init(void)
 	unflatten_and_copy_device_tree();
 }
 
-static int memory_dtb;
-
-static int __init early_init_dt_find_memory(unsigned long node,
-				const char *uname, int depth, void *data)
-{
-	if (depth == 1 && !strcmp(uname, "memory@0"))
-		memory_dtb = 1;
-
-	return 0;
-}
-
 void __init plat_mem_setup(void)
 {
 	void *dtb;
@@ -77,9 +66,8 @@ void __init plat_mem_setup(void)
 	dtb = get_fdt();
 	__dt_setup_arch(dtb);
 
-	of_scan_flat_dt(early_init_dt_find_memory, NULL);
-	if (memory_dtb)
-		of_scan_flat_dt(early_init_dt_scan_memory, NULL);
+	if (!early_init_dt_scan_memory())
+		return;
 	else if (soc_info.mem_detect)
 		soc_info.mem_detect();
 	else if (soc_info.mem_size)
diff --git a/arch/powerpc/kernel/prom.c b/arch/powerpc/kernel/prom.c
index 6e1a106f02eb..63762a3b75e8 100644
--- a/arch/powerpc/kernel/prom.c
+++ b/arch/powerpc/kernel/prom.c
@@ -532,19 +532,19 @@ static int  __init early_init_drmem_lmb(struct drmem_lmb *lmb,
 }
 #endif /* CONFIG_PPC_PSERIES */
 
-static int __init early_init_dt_scan_memory_ppc(unsigned long node,
-						const char *uname,
-						int depth, void *data)
+static int __init early_init_dt_scan_memory_ppc(void)
 {
 #ifdef CONFIG_PPC_PSERIES
-	if (depth == 1 &&
-	    strcmp(uname, "ibm,dynamic-reconfiguration-memory") == 0) {
+	const void *fdt = initial_boot_params;
+	int node = fdt_path_offset(fdt, "/ibm,dynamic-reconfiguration-memory");
+
+	if (node > 0) {
 		walk_drmem_lmbs_early(node, NULL, early_init_drmem_lmb);
 		return 0;
 	}
 #endif
 	
-	return early_init_dt_scan_memory(node, uname, depth, data);
+	return early_init_dt_scan_memory();
 }
 
 /*
@@ -749,7 +749,7 @@ void __init early_init_devtree(void *params)
 
 	/* Scan memory nodes and rebuild MEMBLOCKs */
 	early_init_dt_scan_root();
-	of_scan_flat_dt(early_init_dt_scan_memory_ppc, NULL);
+	early_init_dt_scan_memory_ppc();
 
 	parse_early_param();
 
@@ -858,7 +858,7 @@ void __init early_get_first_memblock_info(void *params, phys_addr_t *size)
 	 */
 	add_mem_to_memblock = 0;
 	early_init_dt_scan_root();
-	of_scan_flat_dt(early_init_dt_scan_memory_ppc, NULL);
+	early_init_dt_scan_memory_ppc();
 	add_mem_to_memblock = 1;
 
 	if (size)
diff --git a/drivers/of/fdt.c b/drivers/of/fdt.c
index 5e216555fe4f..a799117886f4 100644
--- a/drivers/of/fdt.c
+++ b/drivers/of/fdt.c
@@ -1078,49 +1078,53 @@ u64 __init dt_mem_next_cell(int s, const __be32 **cellp)
 /*
  * early_init_dt_scan_memory - Look for and parse memory nodes
  */
-int __init early_init_dt_scan_memory(unsigned long node, const char *uname,
-				     int depth, void *data)
+int __init early_init_dt_scan_memory(void)
 {
-	const char *type = of_get_flat_dt_prop(node, "device_type", NULL);
-	const __be32 *reg, *endp;
-	int l;
-	bool hotpluggable;
+	int node;
+	const void *fdt = initial_boot_params;
 
-	/* We are scanning "memory" nodes only */
-	if (type == NULL || strcmp(type, "memory") != 0)
-		return 0;
+	fdt_for_each_subnode(node, fdt, 0) {
+		const char *type = of_get_flat_dt_prop(node, "device_type", NULL);
+		const __be32 *reg, *endp;
+		int l;
+		bool hotpluggable;
 
-	reg = of_get_flat_dt_prop(node, "linux,usable-memory", &l);
-	if (reg == NULL)
-		reg = of_get_flat_dt_prop(node, "reg", &l);
-	if (reg == NULL)
-		return 0;
+		/* We are scanning "memory" nodes only */
+		if (type == NULL || strcmp(type, "memory") != 0)
+			continue;
 
-	endp = reg + (l / sizeof(__be32));
-	hotpluggable = of_get_flat_dt_prop(node, "hotpluggable", NULL);
+		reg = of_get_flat_dt_prop(node, "linux,usable-memory", &l);
+		if (reg == NULL)
+			reg = of_get_flat_dt_prop(node, "reg", &l);
+		if (reg == NULL)
+			return 0;
 
-	pr_debug("memory scan node %s, reg size %d,\n", uname, l);
+		endp = reg + (l / sizeof(__be32));
+		hotpluggable = of_get_flat_dt_prop(node, "hotpluggable", NULL);
 
-	while ((endp - reg) >= (dt_root_addr_cells + dt_root_size_cells)) {
-		u64 base, size;
+		pr_debug("memory scan node %s, reg size %d,\n",
+			fdt_get_name(fdt, node, NULL), l);
 
-		base = dt_mem_next_cell(dt_root_addr_cells, &reg);
-		size = dt_mem_next_cell(dt_root_size_cells, &reg);
+		while ((endp - reg) >= (dt_root_addr_cells + dt_root_size_cells)) {
+			u64 base, size;
 
-		if (size == 0)
-			continue;
-		pr_debug(" - %llx, %llx\n", base, size);
+			base = dt_mem_next_cell(dt_root_addr_cells, &reg);
+			size = dt_mem_next_cell(dt_root_size_cells, &reg);
 
-		early_init_dt_add_memory_arch(base, size);
+			if (size == 0)
+				continue;
+			pr_debug(" - %llx, %llx\n", base, size);
 
-		if (!hotpluggable)
-			continue;
+			early_init_dt_add_memory_arch(base, size);
 
-		if (memblock_mark_hotplug(base, size))
-			pr_warn("failed to mark hotplug range 0x%llx - 0x%llx\n",
-				base, base + size);
-	}
+			if (!hotpluggable)
+				continue;
 
+			if (memblock_mark_hotplug(base, size))
+				pr_warn("failed to mark hotplug range 0x%llx - 0x%llx\n",
+					base, base + size);
+		}
+	}
 	return 0;
 }
 
@@ -1271,7 +1275,7 @@ void __init early_init_dt_scan_nodes(void)
 		pr_warn("No chosen node found, continuing without\n");
 
 	/* Setup memory, calling early_init_dt_add_memory_arch */
-	of_scan_flat_dt(early_init_dt_scan_memory, NULL);
+	early_init_dt_scan_memory();
 
 	/* Handle linux,usable-memory-range property */
 	memblock_cap_memory_range(cap_mem_addr, cap_mem_size);
diff --git a/include/linux/of_fdt.h b/include/linux/of_fdt.h
index df3d31926c3c..914739f3c192 100644
--- a/include/linux/of_fdt.h
+++ b/include/linux/of_fdt.h
@@ -59,8 +59,7 @@ extern unsigned long of_get_flat_dt_root(void);
 extern uint32_t of_get_flat_dt_phandle(unsigned long node);
 
 extern int early_init_dt_scan_chosen(char *cmdline);
-extern int early_init_dt_scan_memory(unsigned long node, const char *uname,
-				     int depth, void *data);
+extern int early_init_dt_scan_memory(void);
 extern int early_init_dt_scan_chosen_stdout(void);
 extern void early_init_fdt_scan_reserved_mem(void);
 extern void early_init_fdt_reserve_self(void);
-- 
2.32.0

Re: [PATCH 3/3] of/fdt: Rework early_init_dt_scan_memory() to call directly

[Frank Rowand]

On 11/18/21 1:12 PM, Rob Herring wrote:
> 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_memory() to be called directly and use libfdt.
> 
> Cc: John Crispin <john@phrozen.org>
> Cc: Thomas Bogendoerfer <tsbogend@alpha.franken.de>
> Cc: Michael Ellerman <mpe@ellerman.id.au>
> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
> Cc: Paul Mackerras <paulus@samba.org>
> Cc: Frank Rowand <frowand.list@gmail.com>
> Cc: linux-mips@vger.kernel.org
> Cc: linuxppc-dev@lists.ozlabs.org
> Signed-off-by: Rob Herring <robh@kernel.org>
> ---
>  arch/mips/ralink/of.c      | 16 ++-------
>  arch/powerpc/kernel/prom.c | 16 ++++-----
>  drivers/of/fdt.c           | 68 ++++++++++++++++++++------------------
>  include/linux/of_fdt.h     |  3 +-
>  4 files changed, 47 insertions(+), 56 deletions(-)
> 
> diff --git a/arch/mips/ralink/of.c b/arch/mips/ralink/of.c
> index 0135376c5de5..e1d79523343a 100644
> --- a/arch/mips/ralink/of.c
> +++ b/arch/mips/ralink/of.c
> @@ -53,17 +53,6 @@ void __init device_tree_init(void)
>  	unflatten_and_copy_device_tree();
>  }
>  
> -static int memory_dtb;
> -
> -static int __init early_init_dt_find_memory(unsigned long node,
> -				const char *uname, int depth, void *data)
> -{
> -	if (depth == 1 && !strcmp(uname, "memory@0"))
> -		memory_dtb = 1;
> -
> -	return 0;
> -}
> -
>  void __init plat_mem_setup(void)
>  {
>  	void *dtb;
> @@ -77,9 +66,8 @@ void __init plat_mem_setup(void)
>  	dtb = get_fdt();
>  	__dt_setup_arch(dtb);
>  
> -	of_scan_flat_dt(early_init_dt_find_memory, NULL);
> -	if (memory_dtb)
> -		of_scan_flat_dt(early_init_dt_scan_memory, NULL);
> +	if (!early_init_dt_scan_memory())
> +		return;
>  	else if (soc_info.mem_detect)

The previous chunk is now:

   if (XXX)
      return;

instead of:

   if (XXX)
      YYY();

so "else if (soc_info.mem_detect)" should be:

  if (soc_info.mem_detect)

>  		soc_info.mem_detect();
>  	else if (soc_info.mem_size)
> diff --git a/arch/powerpc/kernel/prom.c b/arch/powerpc/kernel/prom.c
> index 6e1a106f02eb..63762a3b75e8 100644
> --- a/arch/powerpc/kernel/prom.c
> +++ b/arch/powerpc/kernel/prom.c
> @@ -532,19 +532,19 @@ static int  __init early_init_drmem_lmb(struct drmem_lmb *lmb,
>  }
>  #endif /* CONFIG_PPC_PSERIES */
>  
> -static int __init early_init_dt_scan_memory_ppc(unsigned long node,
> -						const char *uname,
> -						int depth, void *data)
> +static int __init early_init_dt_scan_memory_ppc(void)
>  {
>  #ifdef CONFIG_PPC_PSERIES
> -	if (depth == 1 &&
> -	    strcmp(uname, "ibm,dynamic-reconfiguration-memory") == 0) {
> +	const void *fdt = initial_boot_params;
> +	int node = fdt_path_offset(fdt, "/ibm,dynamic-reconfiguration-memory");
> +
> +	if (node > 0) {
>  		walk_drmem_lmbs_early(node, NULL, early_init_drmem_lmb);
>  		return 0;
>  	}
>  #endif
>  	
> -	return early_init_dt_scan_memory(node, uname, depth, data);
> +	return early_init_dt_scan_memory();
>  }
>  
>  /*
> @@ -749,7 +749,7 @@ void __init early_init_devtree(void *params)
>  
>  	/* Scan memory nodes and rebuild MEMBLOCKs */
>  	early_init_dt_scan_root();
> -	of_scan_flat_dt(early_init_dt_scan_memory_ppc, NULL);
> +	early_init_dt_scan_memory_ppc();
>  
>  	parse_early_param();
>  
> @@ -858,7 +858,7 @@ void __init early_get_first_memblock_info(void *params, phys_addr_t *size)
>  	 */
>  	add_mem_to_memblock = 0;
>  	early_init_dt_scan_root();
> -	of_scan_flat_dt(early_init_dt_scan_memory_ppc, NULL);
> +	early_init_dt_scan_memory_ppc();
>  	add_mem_to_memblock = 1;
>  
>  	if (size)
> diff --git a/drivers/of/fdt.c b/drivers/of/fdt.c
> index 5e216555fe4f..a799117886f4 100644
> --- a/drivers/of/fdt.c
> +++ b/drivers/of/fdt.c
> @@ -1078,49 +1078,53 @@ u64 __init dt_mem_next_cell(int s, const __be32 **cellp)
>  /*
>   * early_init_dt_scan_memory - Look for and parse memory nodes
>   */
> -int __init early_init_dt_scan_memory(unsigned long node, const char *uname,
> -				     int depth, void *data)
> +int __init early_init_dt_scan_memory(void)
>  {
> -	const char *type = of_get_flat_dt_prop(node, "device_type", NULL);
> -	const __be32 *reg, *endp;
> -	int l;
> -	bool hotpluggable;
> +	int node;
> +	const void *fdt = initial_boot_params;
>  
> -	/* We are scanning "memory" nodes only */
> -	if (type == NULL || strcmp(type, "memory") != 0)
> -		return 0;
> +	fdt_for_each_subnode(node, fdt, 0) {
> +		const char *type = of_get_flat_dt_prop(node, "device_type", NULL);
> +		const __be32 *reg, *endp;
> +		int l;
> +		bool hotpluggable;
>  
> -	reg = of_get_flat_dt_prop(node, "linux,usable-memory", &l);
> -	if (reg == NULL)
> -		reg = of_get_flat_dt_prop(node, "reg", &l);
> -	if (reg == NULL)
> -		return 0;
> +		/* We are scanning "memory" nodes only */
> +		if (type == NULL || strcmp(type, "memory") != 0)
> +			continue;
>  
> -	endp = reg + (l / sizeof(__be32));
> -	hotpluggable = of_get_flat_dt_prop(node, "hotpluggable", NULL);
> +		reg = of_get_flat_dt_prop(node, "linux,usable-memory", &l);
> +		if (reg == NULL)
> +			reg = of_get_flat_dt_prop(node, "reg", &l);
> +		if (reg == NULL)
> +			return 0;

                        Should be "continue" instead of "return 0"?

>  
> -	pr_debug("memory scan node %s, reg size %d,\n", uname, l);
> +		endp = reg + (l / sizeof(__be32));
> +		hotpluggable = of_get_flat_dt_prop(node, "hotpluggable", NULL);
>  
> -	while ((endp - reg) >= (dt_root_addr_cells + dt_root_size_cells)) {
> -		u64 base, size;
> +		pr_debug("memory scan node %s, reg size %d,\n",
> +			fdt_get_name(fdt, node, NULL), l);

Second line of pr_debug() should be indented one more space.

>  
> -		base = dt_mem_next_cell(dt_root_addr_cells, &reg);
> -		size = dt_mem_next_cell(dt_root_size_cells, &reg);
> +		while ((endp - reg) >= (dt_root_addr_cells + dt_root_size_cells)) {
> +			u64 base, size;
>  
> -		if (size == 0)
> -			continue;
> -		pr_debug(" - %llx, %llx\n", base, size);
> +			base = dt_mem_next_cell(dt_root_addr_cells, &reg);
> +			size = dt_mem_next_cell(dt_root_size_cells, &reg);
>  
> -		early_init_dt_add_memory_arch(base, size);
> +			if (size == 0)
> +				continue;
> +			pr_debug(" - %llx, %llx\n", base, size);
>  
> -		if (!hotpluggable)
> -			continue;
> +			early_init_dt_add_memory_arch(base, size);
>  
> -		if (memblock_mark_hotplug(base, size))
> -			pr_warn("failed to mark hotplug range 0x%llx - 0x%llx\n",
> -				base, base + size);
> -	}
> +			if (!hotpluggable)
> +				continue;
>  
> +			if (memblock_mark_hotplug(base, size))
> +				pr_warn("failed to mark hotplug range 0x%llx - 0x%llx\n",
> +					base, base + size);
> +		}
> +	}
>  	return 0;
>  }
>  
> @@ -1271,7 +1275,7 @@ void __init early_init_dt_scan_nodes(void)
>  		pr_warn("No chosen node found, continuing without\n");
>  
>  	/* Setup memory, calling early_init_dt_add_memory_arch */
> -	of_scan_flat_dt(early_init_dt_scan_memory, NULL);
> +	early_init_dt_scan_memory();
>  
>  	/* Handle linux,usable-memory-range property */
>  	memblock_cap_memory_range(cap_mem_addr, cap_mem_size);
> diff --git a/include/linux/of_fdt.h b/include/linux/of_fdt.h
> index df3d31926c3c..914739f3c192 100644
> --- a/include/linux/of_fdt.h
> +++ b/include/linux/of_fdt.h
> @@ -59,8 +59,7 @@ extern unsigned long of_get_flat_dt_root(void);
>  extern uint32_t of_get_flat_dt_phandle(unsigned long node);
>  
>  extern int early_init_dt_scan_chosen(char *cmdline);
> -extern int early_init_dt_scan_memory(unsigned long node, const char *uname,
> -				     int depth, void *data);
> +extern int early_init_dt_scan_memory(void);
>  extern int early_init_dt_scan_chosen_stdout(void);
>  extern void early_init_fdt_scan_reserved_mem(void);
>  extern void early_init_fdt_reserve_self(void);
> 

Re: [PATCH 0/3] of/fdt: Rework early FDT scanning functions

[Frank Rowand]

On 11/18/21 1:12 PM, Rob Herring wrote:
> The early FDT scanning functions use of_scan_flat_dt() which implements 
> its own node walking method. This function predates libfdt and is an 
> unnecessary indirection. This series reworks 
> early_init_dt_scan_chosen(), early_init_dt_scan_root(), and 
> early_init_dt_scan_memory() to be called directly and use libfdt calls.
> 
> Ultimately, I want to remove of_scan_flat_dt(). Most of the remaining 
> of_scan_flat_dt() users are in powerpc.
> 
> Rob
> 
> 
> Rob Herring (3):
>   of/fdt: Rework early_init_dt_scan_chosen() to call directly
>   of/fdt: Rework early_init_dt_scan_root() to call directly
>   of/fdt: Rework early_init_dt_scan_memory() to call directly
> 
>  arch/mips/ralink/of.c                |  16 +---
>  arch/powerpc/kernel/prom.c           |  22 ++---
>  arch/powerpc/mm/nohash/kaslr_booke.c |   4 +-
>  drivers/of/fdt.c                     | 121 ++++++++++++++-------------
>  include/linux/of_fdt.h               |   9 +-
>  5 files changed, 79 insertions(+), 93 deletions(-)
> 


"checkpatch --strict" reports some "CHECK" issues, but review of the patches
for correctness becomes much more difficult if they are addressed, so they
should be ignored for this series.

-Frank