[U-Boot] [PATCH v3] PXE: FDT: Add support for fdt in PXE

[Chander Kashyap]

Now DT support is becomming common for all new SoC's. Hence it is better to
have option for getting specific FDT from the remote server.

This patch adds support for new lable i.e. fdt. If fdt_addr is specified
then load fdt blob from the remote server to fdt_address.

Signed-off-by: Chander Kashyap <chander.kashyap at linaro.org>
---
Changes in v2:
	- Removed the duplicate code.
changes in v3:
	- Added documentation for "fdt" lable in doc/README.pxe 

 common/cmd_pxe.c |   23 +++++++++++++++++++++++
 doc/README.pxe   |   10 ++++++++--
 2 files changed, 31 insertions(+), 2 deletions(-)

diff --git a/common/cmd_pxe.c b/common/cmd_pxe.c
index 6b31dea..0c81e08 100644
--- a/common/cmd_pxe.c
+++ b/common/cmd_pxe.c
@@ -450,6 +450,7 @@ struct pxe_label {
 	char *kernel;
 	char *append;
 	char *initrd;
+	char *fdt;
 	int attempted;
 	int localboot;
 	struct list_head list;
@@ -517,6 +518,9 @@ static void label_destroy(struct pxe_label *label)
 	if (label->initrd)
 		free(label->initrd);
 
+	if (label->fdt)
+		free(label->fdt);
+
 	free(label);
 }
 
@@ -541,6 +545,9 @@ static void label_print(void *data)
 
 	if (label->initrd)
 		printf("\t\tinitrd: %s\n", label->initrd);
+
+	if (label->fdt)
+		printf("\tfdt: %s\n", label->fdt);
 }
 
 /*
@@ -633,6 +640,15 @@ static void label_boot(struct pxe_label *label)
 	 */
 	bootm_argv[3] = getenv("fdt_addr");
 
+	/* if fdt label is defined then get fdt from server */
+	if (bootm_argv[3] && label->fdt) {
+		if (get_relfile_envaddr(label->fdt, "fdt_addr") < 0) {
+			printf("Skipping %s for failure retrieving fdt\n",
+					label->name);
+			return;
+		}
+	}
+
 	if (bootm_argv[3])
 		bootm_argc = 4;
 
@@ -658,6 +674,7 @@ enum token_type {
 	T_DEFAULT,
 	T_PROMPT,
 	T_INCLUDE,
+	T_FDT,
 	T_INVALID
 };
 
@@ -685,6 +702,7 @@ static const struct token keywords[] = {
 	{"append", T_APPEND},
 	{"initrd", T_INITRD},
 	{"include", T_INCLUDE},
+	{"fdt", T_FDT},
 	{NULL, T_INVALID}
 };
 
@@ -1074,6 +1092,11 @@ static int parse_label(char **c, struct pxe_menu *cfg)
 				err = parse_sliteral(c, &label->initrd);
 			break;
 
+		case T_FDT:
+			if (!label->fdt)
+				err = parse_sliteral(c, &label->fdt);
+			break;
+
 		case T_LOCALBOOT:
 			err = parse_integer(c, &label->localboot);
 			break;
diff --git a/doc/README.pxe b/doc/README.pxe
index 2bbf53d..835ca5a 100644
--- a/doc/README.pxe
+++ b/doc/README.pxe
@@ -93,8 +93,9 @@ pxe boot
      be passed to the bootm command to boot the kernel. These environment
      variables are required to be set.
 
-     fdt_addr - the location of a fdt blob. If this is set, it will be passed
-     to bootm when booting a kernel.
+     fdt_addr - locations in RAM at which 'pxe boot' will store the fdt blob
+     it retrieves from tftp, if "fdt" lable is defined in pxe file. If this is
+     set, it will be passed to bootm when booting a kernel.
 
 pxe file format
 ===============
@@ -156,6 +157,11 @@ initrd <path>	    - if this label is chosen, use tftp to retrieve the initrd
 		      the initrd_addr_r environment variable, and that address
 		      will be passed to bootm.
 
+fdt <path>	    - if this label is chosen, use tftp to retrieve the fdt blob
+		      at <path>. it will be stored at the address indicated in
+		      the fdt_addr environment variable, and that address will
+		      be passed to bootm.
+
 localboot <flag>    - Run the command defined by "localcmd" in the environment.
 		      <flag> is ignored and is only here to match the syntax of
 		      PXELINUX config files.
-- 
1.7.9.5