target/linux/ipq806x/patches-4.4/996-ATAG_DTB_COMPAT_CMDLINE_MANGLE.patch

   1 Author: Adrian Panella <ianchi74@outlook.com>
   2 Date:   Fri Jun 10 19:10:15 2016 -0500
   3
   4 generic: Mangle bootloader's kernel arguments
   5
   6 The command-line arguments provided by the boot loader will be
   7 appended to a new device tree property: bootloader-args.
   8 If there is a property "append-rootblock" in DT under /chosen
   9 and a root= option in bootloaders command line it will be parsed
  10 and added to DT bootargs with the form: <append-rootblock>XX.
  11 Only command line ATAG will be processed, the rest of the ATAGs
  12 sent by bootloader will be ignored.
  13 This is usefull in dual boot systems, to get the current root partition
  14 without afecting the rest of the system.
  15
  16
  17 Signed-off-by: Adrian Panella <ianchi74@outlook.com>
  18
  19 --- a/arch/arm/Kconfig
  20 +++ b/arch/arm/Kconfig
  21 @@ -1928,6 +1928,17 @@ config ARM_ATAG_DTB_COMPAT_CMDLINE_EXTEN
  22           The command-line arguments provided by the boot loader will be
  23           appended to the the device tree bootargs property.
  24
  25 +config ARM_ATAG_DTB_COMPAT_CMDLINE_MANGLE
  26 +       bool "Append rootblock parsing bootloader's kernel arguments"
  27 +       help
  28 +         The command-line arguments provided by the boot loader will be
  29 +         appended to a new device tree property: bootloader-args.
  30 +         If there is a property "append-rootblock" in DT under /chosen
  31 +         and a root= option in bootloaders command line it will be parsed
  32 +         and added to DT bootargs with the form: <append-rootblock>XX.
  33 +         Only command line ATAG will be processed, the rest of the ATAGs
  34 +         sent by bootloader will be ignored.
  35 +
  36  endchoice
  37
  38  config CMDLINE
  39 --- a/arch/arm/boot/compressed/atags_to_fdt.c
  40 +++ b/arch/arm/boot/compressed/atags_to_fdt.c
  41 @@ -3,6 +3,8 @@
  42
  43  #if defined(CONFIG_ARM_ATAG_DTB_COMPAT_CMDLINE_EXTEND)
  44  #define do_extend_cmdline 1
  45 +#elif defined(CONFIG_ARM_ATAG_DTB_COMPAT_CMDLINE_MANGLE)
  46 +#define do_extend_cmdline 1
  47  #else
  48  #define do_extend_cmdline 0
  49  #endif
  50 @@ -66,6 +68,59 @@ static uint32_t get_cell_size(const void
  51         return cell_size;
  52  }
  53
  54 +#if defined(CONFIG_ARM_ATAG_DTB_COMPAT_CMDLINE_MANGLE)
  55 +
  56 +static char *append_rootblock(char *dest, const char *str, int len, void *fdt)
  57 +{
  58 +       char *ptr, *end;
  59 +       char *root="root=";
  60 +       int i, l;
  61 +       const char *rootblock;
  62 +
  63 +       //ARM doesn't have __HAVE_ARCH_STRSTR, so search manually
  64 +       ptr = str - 1;
  65 +
  66 +       do {
  67 +               //first find an 'r' at the begining or after a space
  68 +               do {
  69 +                       ptr++;
  70 +                       ptr = strchr(ptr, 'r');
  71 +                       if(!ptr) return dest;
  72 +
  73 +               } while (ptr != str && *(ptr-1) != ' ');
  74 +
  75 +               //then check for the rest
  76 +               for(i = 1; i <= 4; i++)
  77 +                       if(*(ptr+i) != *(root+i)) break;
  78 +
  79 +       } while (i != 5);
  80 +
  81 +       end = strchr(ptr, ' ');
  82 +       end = end ? (end - 1) : (strchr(ptr, 0) - 1);
  83 +
  84 +       //find partition number (assumes format root=/dev/mtdXX | /dev/mtdblockXX | yy:XX )
  85 +       for( i = 0; end >= ptr && *end >= '0' && *end <= '9'; end--, i++);
  86 +       ptr = end + 1;
  87 +
  88 +       /* if append-rootblock property is set use it to append to command line */
  89 +       rootblock = getprop(fdt, "/chosen", "append-rootblock", &l);
  90 +       if(rootblock != NULL) {
  91 +               if(*dest != ' ') {
  92 +                       *dest = ' ';
  93 +                       dest++;
  94 +                       len++;
  95 +               }
  96 +               if (len + l + i <= COMMAND_LINE_SIZE) {
  97 +                       memcpy(dest, rootblock, l);
  98 +                       dest += l - 1;
  99 +                       memcpy(dest, ptr, i);
 100 +                       dest += i;
 101 +               }
 102 +       }
 103 +       return dest;
 104 +}
 105 +#endif
 106 +
 107  static void merge_fdt_bootargs(void *fdt, const char *fdt_cmdline)
 108  {
 109         char cmdline[COMMAND_LINE_SIZE];
 110 @@ -85,12 +140,21 @@ static void merge_fdt_bootargs(void *fdt
 111
 112         /* and append the ATAG_CMDLINE */
 113         if (fdt_cmdline) {
 114 +
 115 +#if defined(CONFIG_ARM_ATAG_DTB_COMPAT_CMDLINE_MANGLE)
 116 +               //save original bootloader args
 117 +               //and append ubi.mtd with root partition number to current cmdline
 118 +               setprop_string(fdt, "/chosen", "bootloader-args", fdt_cmdline);
 119 +               ptr = append_rootblock(ptr, fdt_cmdline, len, fdt);
 120 +
 121 +#else
 122                 len = strlen(fdt_cmdline);
 123                 if (ptr - cmdline + len + 2 < COMMAND_LINE_SIZE) {
 124                         *ptr++ = ' ';
 125                         memcpy(ptr, fdt_cmdline, len);
 126                         ptr += len;
 127                 }
 128 +#endif
 129         }
 130         *ptr = '\0';
 131
 132 @@ -147,7 +211,9 @@ int atags_to_fdt(void *atag_list, void *
 133                         else
 134                                 setprop_string(fdt, "/chosen", "bootargs",
 135                                                atag->u.cmdline.cmdline);
 136 -               } else if (atag->hdr.tag == ATAG_MEM) {
 137 +               }
 138 +#ifndef CONFIG_ARM_ATAG_DTB_COMPAT_CMDLINE_MANGLE
 139 +               else if (atag->hdr.tag == ATAG_MEM) {
 140                         if (memcount >= sizeof(mem_reg_property)/4)
 141                                 continue;
 142                         if (!atag->u.mem.size)
 143 @@ -186,6 +252,10 @@ int atags_to_fdt(void *atag_list, void *
 144                 setprop(fdt, "/memory", "reg", mem_reg_property,
 145                         4 * memcount * memsize);
 146         }
 147 +#else
 148 +
 149 +       }
 150 +#endif
 151
 152         return fdt_pack(fdt);
 153  }
 154 --- a/init/main.c
 155 +++ b/init/main.c
 156 @@ -88,6 +88,10 @@
 157  #include <asm/sections.h>
 158  #include <asm/cacheflush.h>
 159
 160 +#if defined(CONFIG_ARM_ATAG_DTB_COMPAT_CMDLINE_MANGLE)
 161 +#include <linux/of.h>
 162 +#endif
 163 +
 164  static int kernel_init(void *);
 165
 166  extern void init_IRQ(void);
 167 @@ -560,6 +564,18 @@ asmlinkage __visible void __init start_k
 168         page_alloc_init();
 169
 170         pr_notice("Kernel command line: %s\n", boot_command_line);
 171 +
 172 +#if defined(CONFIG_ARM_ATAG_DTB_COMPAT_CMDLINE_MANGLE)
 173 +       //Show bootloader's original command line for reference
 174 +       if(of_chosen) {
 175 +               const char *prop = of_get_property(of_chosen, "bootloader-args", NULL);
 176 +               if(prop)
 177 +                       pr_notice("Bootloader command line (ignored): %s\n", prop);
 178 +               else
 179 +                       pr_notice("Bootloader command line not present\n");
 180 +       }
 181 +#endif
 182 +
 183         parse_early_param();
 184         after_dashes = parse_args("Booting kernel",
 185                                   static_command_line, __start___param,