ipq806x: activate ATAG DTB mangle and EA8500 rootblock in dts

The command-line arguments provided by the boot loader will be
appended to a new device tree property: bootloader-args.
If there is a property "append-rootblock" in DT under /chosen
and a root= option in bootloaders command line it will be parsed
and added to DT bootargs with the form: <append-rootblock>XX.
Only command line ATAG will be processed, the rest of the ATAGs
sent by bootloader will be ignored.
This is usefull in dual boot systems, to get the current root partition
without afecting the rest of the system.

Signed-off-by: Adrian Panella <ianchi74@outlook.com>

3 files changed, 190 insertions, 1 deletions

diff --git a/target/linux/ipq806x/config-4.4 b/target/linux/ipq806x/config-4.4
index 555247aba5..a6badc9a52 100644
--- a/target/linux/ipq806x/config-4.4
+++ b/target/linux/ipq806x/config-4.4
@@ -37,7 +37,10 @@ CONFIG_ARM_AMBA=y
 CONFIG_ARM_APPENDED_DTB=y
 CONFIG_ARM_ARCH_TIMER=y
 CONFIG_ARM_ARCH_TIMER_EVTSTREAM=y
-# CONFIG_ARM_ATAG_DTB_COMPAT is not set
+CONFIG_ARM_ATAG_DTB_COMPAT=y
+# CONFIG_ARM_ATAG_DTB_COMPAT_CMDLINE_EXTEND is not set
+# CONFIG_ARM_ATAG_DTB_COMPAT_CMDLINE_FROM_BOOTLOADER is not set
+CONFIG_ARM_ATAG_DTB_COMPAT_CMDLINE_MANGLE=y
 CONFIG_ARM_CCI=y
 CONFIG_ARM_CCI400_COMMON=y
 CONFIG_ARM_CCI400_PMU=y
diff --git a/target/linux/ipq806x/files/arch/arm/boot/dts/qcom-ipq8064-ea8500.dts b/target/linux/ipq806x/files/arch/arm/boot/dts/qcom-ipq8064-ea8500.dts
index 2c5e1107a1..4576a715ef 100644
--- a/target/linux/ipq806x/files/arch/arm/boot/dts/qcom-ipq8064-ea8500.dts
+++ b/target/linux/ipq806x/files/arch/arm/boot/dts/qcom-ipq8064-ea8500.dts
@@ -29,6 +29,7 @@
 	chosen {
 		bootargs = "console=ttyMSM0,115200n8"; 
 		linux,stdout-path = "serial0:115200n8";
+		append-rootblock = "ubi.mtd=";  /* append to bootargs adding the root deviceblock nbr from bootloader */
 	};
 
 	soc {
diff --git a/target/linux/ipq806x/patches-4.4/996-ATAG_DTB_COMPAT_CMDLINE_MANGLE.patch b/target/linux/ipq806x/patches-4.4/996-ATAG_DTB_COMPAT_CMDLINE_MANGLE.patch
new file mode 100644
index 0000000000..490886ee44
--- /dev/null
+++ b/target/linux/ipq806x/patches-4.4/996-ATAG_DTB_COMPAT_CMDLINE_MANGLE.patch
@@ -0,0 +1,185 @@
+Author: Adrian Panella <ianchi74@outlook.com>
+Date:   Fri Jun 10 19:10:15 2016 -0500
+
+generic: Mangle bootloader's kernel arguments
+
+The command-line arguments provided by the boot loader will be
+appended to a new device tree property: bootloader-args.
+If there is a property "append-rootblock" in DT under /chosen
+and a root= option in bootloaders command line it will be parsed
+and added to DT bootargs with the form: <append-rootblock>XX.
+Only command line ATAG will be processed, the rest of the ATAGs
+sent by bootloader will be ignored.
+This is usefull in dual boot systems, to get the current root partition
+without afecting the rest of the system.
+
+
+Signed-off-by: Adrian Panella <ianchi74@outlook.com>
+
+--- a/arch/arm/Kconfig
++++ b/arch/arm/Kconfig
+@@ -1927,6 +1927,17 @@ config ARM_ATAG_DTB_COMPAT_CMDLINE_EXTEN
+ 	  The command-line arguments provided by the boot loader will be
+ 	  appended to the the device tree bootargs property.
+ 
++config ARM_ATAG_DTB_COMPAT_CMDLINE_MANGLE
++	bool "Append rootblock parsing bootloader's kernel arguments"
++	help
++	  The command-line arguments provided by the boot loader will be
++	  appended to a new device tree property: bootloader-args.
++	  If there is a property "append-rootblock" in DT under /chosen 
++	  and a root= option in bootloaders command line it will be parsed 
++	  and added to DT bootargs with the form: <append-rootblock>XX.
++	  Only command line ATAG will be processed, the rest of the ATAGs
++	  sent by bootloader will be ignored.
++
+ endchoice
+ 
+ config CMDLINE
+--- a/arch/arm/boot/compressed/atags_to_fdt.c
++++ b/arch/arm/boot/compressed/atags_to_fdt.c
+@@ -3,6 +3,8 @@
+ 
+ #if defined(CONFIG_ARM_ATAG_DTB_COMPAT_CMDLINE_EXTEND)
+ #define do_extend_cmdline 1
++#elif defined(CONFIG_ARM_ATAG_DTB_COMPAT_CMDLINE_MANGLE)
++#define do_extend_cmdline 1
+ #else
+ #define do_extend_cmdline 0
+ #endif
+@@ -66,6 +68,59 @@ static uint32_t get_cell_size(const void
+ 	return cell_size;
+ }
+ 
++#if defined(CONFIG_ARM_ATAG_DTB_COMPAT_CMDLINE_MANGLE)
++
++static char *append_rootblock(char *dest, const char *str, int len, void *fdt)
++{
++	char *ptr, *end;
++	char *root="root=";
++	int i, l;
++	const char *rootblock;
++
++	//ARM doesn't have __HAVE_ARCH_STRSTR, so search manually
++	ptr = str - 1;
++
++	do {
++		ptr++;
++		//first find an 'r' at the begining or after a space
++		do {
++			ptr = strchr(ptr, 'r');
++			if(!ptr) return dest;
++
++		} while (ptr != str && *(ptr-1) != ' ');
++
++		//then check for the rest
++		for(i = 1; i <= 4; i++)
++			if(*(ptr+i) != *(root+i)) break;
++
++	} while (i != 5);
++
++	end = strchr(ptr, ' ');
++	end = end ? (end - 1) : (strchr(ptr, 0) - 1);
++
++	//find partition number (assumes format root=/dev/mtdXX | /dev/mtdblockXX | yy:XX )
++	for( i = 0; end >= ptr && *end >= '0' && *end <= '9'; end--, i++);
++	ptr = end + 1;
++
++	/* if append-rootblock property is set use it to append to command line */
++	rootblock = getprop(fdt, "/chosen", "append-rootblock", &l);
++	if(rootblock != NULL) {
++		if(*dest != ' ') {
++			*dest = ' ';
++			dest++;
++			len++;
++		}
++		if (len + l + i <= COMMAND_LINE_SIZE) {
++			memcpy(dest, rootblock, l);
++			dest += l - 1;
++			memcpy(dest, ptr, i);
++			dest += i;
++		}
++	}
++	return dest;
++}
++#endif
++
+ static void merge_fdt_bootargs(void *fdt, const char *fdt_cmdline)
+ {
+ 	char cmdline[COMMAND_LINE_SIZE];
+@@ -85,12 +134,21 @@ static void merge_fdt_bootargs(void *fdt
+ 
+ 	/* and append the ATAG_CMDLINE */
+ 	if (fdt_cmdline) {
++
++#if defined(CONFIG_ARM_ATAG_DTB_COMPAT_CMDLINE_MANGLE)
++		//save original bootloader args
++		//and append ubi.mtd with root partition number to current cmdline
++		setprop_string(fdt, "/chosen", "bootloader-args", fdt_cmdline);
++		ptr = append_rootblock(ptr, fdt_cmdline, len, fdt);
++
++#else
+ 		len = strlen(fdt_cmdline);
+ 		if (ptr - cmdline + len + 2 < COMMAND_LINE_SIZE) {
+ 			*ptr++ = ' ';
+ 			memcpy(ptr, fdt_cmdline, len);
+ 			ptr += len;
+ 		}
++#endif
+ 	}
+ 	*ptr = '\0';
+ 
+@@ -147,7 +205,9 @@ int atags_to_fdt(void *atag_list, void *
+ 			else
+ 				setprop_string(fdt, "/chosen", "bootargs",
+ 					       atag->u.cmdline.cmdline);
+-		} else if (atag->hdr.tag == ATAG_MEM) {
++		}
++#ifndef CONFIG_ARM_ATAG_DTB_COMPAT_CMDLINE_MANGLE
++		else if (atag->hdr.tag == ATAG_MEM) {
+ 			if (memcount >= sizeof(mem_reg_property)/4)
+ 				continue;
+ 			if (!atag->u.mem.size)
+@@ -186,6 +246,10 @@ int atags_to_fdt(void *atag_list, void *
+ 		setprop(fdt, "/memory", "reg", mem_reg_property,
+ 			4 * memcount * memsize);
+ 	}
++#else
++
++	}
++#endif
+ 
+ 	return fdt_pack(fdt);
+ }
+--- a/init/main.c
++++ b/init/main.c
+@@ -88,6 +88,10 @@
+ #include <asm/sections.h>
+ #include <asm/cacheflush.h>
+ 
++#if defined(CONFIG_ARM_ATAG_DTB_COMPAT_CMDLINE_MANGLE)
++#include <linux/of.h>
++#endif
++
+ static int kernel_init(void *);
+ 
+ extern void init_IRQ(void);
+@@ -585,6 +589,18 @@ asmlinkage __visible void __init start_k
+ 	page_alloc_init();
+ 
+ 	pr_notice("Kernel command line: %s\n", boot_command_line);
++
++#if defined(CONFIG_ARM_ATAG_DTB_COMPAT_CMDLINE_MANGLE)
++	//Show bootloader's original command line for reference
++	if(of_chosen) {
++		const char *prop = of_get_property(of_chosen, "bootloader-args", NULL);
++		if(prop)
++			pr_notice("Bootloader command line (ignored): %s\n", prop);
++		else
++			pr_notice("Bootloader command line not present\n");
++	}
++#endif
++
+ 	parse_early_param();
+ 	after_dashes = parse_args("Booting kernel",
+ 				  static_command_line, __start___param,