mvebu: fix broken console on WRT32X (venom)

The console bootarg is being corrupted on boot, causing various issues
including broken sysupgrade.
Utilising the bootargs mangle patch from other targets, hardcode the console
arguments and fetch the rootfs from the bootloader.

Kernel command line: console=ttyS0,115200 root=/dev/mtdblock8

Bootloader command line (ignored): console= root=/dev/mtdblock8

Please cherry pick to 18.06 too

Signed-off-by: Michael Gray <michael.gray@lantisproject.com>
(cherry picked from commit 4fdc6ca31bda4aad2a65b8460b0caa5c60f87f41)

3 files changed, 208 insertions, 0 deletions

diff --git a/target/linux/mvebu/config-4.14 b/target/linux/mvebu/config-4.14
index a48a3c8c5e..694ecdfb82 100644
--- a/target/linux/mvebu/config-4.14
+++ b/target/linux/mvebu/config-4.14
@@ -42,6 +42,7 @@ CONFIG_ARM_APPENDED_DTB=y
 CONFIG_ARM_ATAG_DTB_COMPAT=y
 # CONFIG_ARM_ATAG_DTB_COMPAT_CMDLINE_EXTEND is not set
 CONFIG_ARM_ATAG_DTB_COMPAT_CMDLINE_FROM_BOOTLOADER=y
+CONFIG_ARM_ATAG_DTB_COMPAT_CMDLINE_MANGLE=y
 CONFIG_ARM_CPU_SUSPEND=y
 CONFIG_ARM_CRYPTO=y
 CONFIG_ARM_ERRATA_720789=y
diff --git a/target/linux/mvebu/files-4.14/arch/arm/boot/dts/armada-385-linksys-venom.dts b/target/linux/mvebu/files-4.14/arch/arm/boot/dts/armada-385-linksys-venom.dts
index ea44c8f0d2..00a4ee9f39 100644
--- a/target/linux/mvebu/files-4.14/arch/arm/boot/dts/armada-385-linksys-venom.dts
+++ b/target/linux/mvebu/files-4.14/arch/arm/boot/dts/armada-385-linksys-venom.dts
@@ -46,7 +46,13 @@
 	model = "Linksys WRT32X";
 	compatible = "linksys,venom", "linksys,armada385", "marvell,armada385",
 		     "marvell,armada380";
+
+	chosen {
+		bootargs = "console=ttyS0,115200";
+		stdout-path = "serial0:115200n8";
+		append-rootblock = "root=/dev/mtdblock";
 	};
+};
 
 	&expander0 {
 			wan_amber@0 {
diff --git a/target/linux/mvebu/patches-4.14/006-mvebu-Mangle-bootloader-s-kernel-arguments.patch b/target/linux/mvebu/patches-4.14/006-mvebu-Mangle-bootloader-s-kernel-arguments.patch
new file mode 100644
index 0000000000..53275607e0
--- /dev/null
+++ b/target/linux/mvebu/patches-4.14/006-mvebu-Mangle-bootloader-s-kernel-arguments.patch
@@ -0,0 +1,201 @@
+From 71270226b14733a4b1f2cde58ea9265caa50b38d Mon Sep 17 00:00:00 2001
+From: Adrian Panella <ianchi74@outlook.com>
+Date: Thu, 9 Mar 2017 09:37:17 +0100
+Subject: [PATCH 67/69] 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>
+
+This patch has been modified to be mvebu specific. The original patch 
+did not pass the bootloader cmdline on if no append-rootblock stanza 
+was found, resulting in blank cmdline and failure to boot.
+
+Signed-off-by: Michael Gray <michael.gray@lantisproject.com>
+---
+ arch/arm/Kconfig                        | 11 +++++
+ arch/arm/boot/compressed/atags_to_fdt.c | 72 ++++++++++++++++++++++++++++++++-
+ init/main.c                             | 16 ++++++++
+ 3 files changed, 98 insertions(+), 1 deletion(-)
+
+--- a/arch/arm/Kconfig
++++ b/arch/arm/Kconfig
+@@ -1948,6 +1948,17 @@ 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 +68,65 @@ 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 {
++		//first find an 'r' at the begining or after a space
++		do {
++			ptr++;
++			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;
++		}
++	} else {
++		len = strlen(str);
++		if (len + 1 < COMMAND_LINE_SIZE) {
++			memcpy(dest, str, len);
++			dest += len;
++		}
++	}
++	return dest;
++}
++#endif
++
+ static void merge_fdt_bootargs(void *fdt, const char *fdt_cmdline)
+ {
+ 	char cmdline[COMMAND_LINE_SIZE];
+@@ -85,12 +140,21 @@ 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 +211,9 @@ 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 +252,10 @@ 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
+@@ -89,6 +89,10 @@
+ #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);
+@@ -540,6 +544,18 @@ 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,