* Modify bootm command to support booting with flat device trees

Patch by Matthew McClintock 26-June-2006

README

@@ -447,6 +447,11 @@ The following options need to be configured:
 		Board code has addition modification that it wants to make
 		to the flat device tree before handing it off to the kernel
 
+		CONFIG_OF_BOOT_CPU
+
+		This define fills in the correct boot cpu in the boot
+		param header, the default value is zero if undefined.
+
 - Serial Ports:
 		CFG_PL010_SERIAL
 
@@ -3013,6 +3018,55 @@ format!) to the "bootm" command:
 
 	bash#
 
+Boot Linux and pass a flat device tree:
+-----------
+
+First, U-Boot must be compiled with the appropriate defines. See the section
+titled "Linux Kernel Interface" above for a more in depth explanation. The
+following is an example of how to start a kernel and pass an updated
+flat device tree:
+
+=> print oftaddr
+oftaddr=0x300000
+=> print oft
+oft=oftrees/mpc8540ads.dtb
+=> tftp $oftaddr $oft
+Speed: 1000, full duplex
+Using TSEC0 device
+TFTP from server 192.168.1.1; our IP address is 192.168.1.101
+Filename 'oftrees/mpc8540ads.dtb'.
+Load address: 0x300000
+Loading: #
+done
+Bytes transferred = 4106 (100a hex)
+=> tftp $loadaddr $bootfile
+Speed: 1000, full duplex
+Using TSEC0 device
+TFTP from server 192.168.1.1; our IP address is 192.168.1.2
+Filename 'uImage'.
+Load address: 0x200000
+Loading:############
+done
+Bytes transferred = 1029407 (fb51f hex)
+=> print loadaddr
+loadaddr=200000
+=> print oftaddr
+oftaddr=0x300000
+=> bootm $loadaddr - $oftaddr
+## Booting image at 00200000 ...
+   Image Name:   Linux-2.6.17-dirty
+   Image Type:   PowerPC Linux Kernel Image (gzip compressed)
+   Data Size:    1029343 Bytes = 1005.2 kB
+   Load Address: 00000000
+   Entry Point:  00000000
+   Verifying Checksum ... OK
+   Uncompressing Kernel Image ... OK
+Booting using flat device tree at 0x300000
+Using MPC85xx ADS machine description
+Memory CAM mapping: CAM0=256Mb, CAM1=256Mb, CAM2=0Mb residual: 0Mb
+[snip]
+
+
 More About U-Boot Image Types:
 ------------------------------
 

common/cmd_bootm.c

@@ -465,6 +465,13 @@ U_BOOT_CMD(
  	"[addr [arg ...]]\n    - boot application image stored in memory\n"
  	"\tpassing arguments 'arg ...'; when booting a Linux kernel,\n"
  	"\t'arg' can be the address of an initrd image\n"
+#ifdef CONFIG_OF_FLAT_TREE
+	"\tWhen booting a Linux kernel which requires a flat device-tree\n"
+	"\ta third argument is required which is the address of the of the\n"
+	"\tdevice-tree blob. To boot that kernel without an initrd image,\n"
+	"\tuse a '-' for the second argument. If you do not pass a third\n"
+	"\ta bd_info struct will be passed instead\n"
+#endif
 );
 
 #ifdef CONFIG_SILENT_CONSOLE
@@ -500,11 +507,6 @@ fixup_silent_linux ()
 }
 #endif /* CONFIG_SILENT_CONSOLE */
 
-#ifdef CONFIG_OF_FLAT_TREE
-extern const unsigned char oftree_dtb[];
-extern const unsigned int oftree_dtb_len;
-#endif
-
 #ifdef CONFIG_PPC
 static void
 do_bootm_linux (cmd_tbl_t *cmdtp, int flag,
@@ -616,7 +618,17 @@ do_bootm_linux (cmd_tbl_t *cmdtp, int flag,
 	/*
 	 * Check if there is an initrd image
 	 */
+
+#ifdef CONFIG_OF_FLAT_TREE
+	/* Look for a '-' which indicates to ignore the ramdisk argument */
+	if (argc >= 3 && strcmp(argv[2], "-") ==  0) {
+			debug ("Skipping initrd\n");
+			data = 0;
+		}
+	else
+#endif
 	if (argc >= 3) {
+		debug ("Not skipping initrd\n");
 		SHOW_BOOT_PROGRESS (9);
 
 		addr = simple_strtoul(argv[2], NULL, 16);
@@ -724,6 +736,15 @@ do_bootm_linux (cmd_tbl_t *cmdtp, int flag,
 		len = data = 0;
 	}
 
+#ifdef CONFIG_OF_FLAT_TREE
+	if (argc >= 3)
+	{
+		of_flat_tree = (char *) simple_strtoul(argv[3], NULL, 16);
+		printf ("Booting using flat device tree at 0x%x\n",
+				of_flat_tree);
+	}
+#endif
+
 	if (!data) {
 		debug ("No initrd\n");
 	}
@@ -793,15 +814,6 @@ do_bootm_linux (cmd_tbl_t *cmdtp, int flag,
 		initrd_end = 0;
 	}
 
-#ifdef CONFIG_OF_FLAT_TREE
-	if (initrd_start == 0)
-		of_flat_tree = (char *)(((ulong)kbd - OF_FLAT_TREE_MAX_SIZE -
-					sizeof(bd_t)) & ~0xF);
-	else
-		of_flat_tree = (char *)((initrd_start - OF_FLAT_TREE_MAX_SIZE -
-					sizeof(bd_t)) & ~0xF);
-#endif
-
 	debug ("## Transferring control to Linux (at address %08lx) ...\n",
 		(ulong)kernel);