MIPS: Add support for GZIP / BZIP2 / LZMA compressed kernel images

This patch helps to generate smaller kernel images for linux-MIPS,

Here is the effect when using lzma:

$ ls -sh vmlinux
7.1M vmlinux
$ ls -sh vmlinuz
1.5M vmlinuz

Have tested the 32bit kernel on Qemu/Malta and 64bit kernel on FuLoong
Mini PC. both of them work well. and also, tested by Alexander Clouter
on an AR7 based Linksys WAG54Gv2, and by Manuel Lauss on an Alchemy
board.

This -v2 version incorporate the feedback from Ralf, and add the
following changes:

1. add .ecoff, .bin, .erec format support
2. only enable it and the debug source code for the machines we tested
3. a dozen of fixups and cleanups

and if you want to enable it for your board, please try to select
SYS_SUPPORTS_ZBOOT for it, and if the board have an 16550 compatible
uart, you can select SYS_SUPPORTS_ZBOOT_UART16550 directly. and then
sending the relative patches to Ralf.

Tested-by: Manuel Lauss <manuel.lauss@googlemail.com>
Tested-by: Alexander Clouter <alex@digriz.org.uk>
Signed-off-by: Wu Zhangjin <wuzhangjin@gmail.com>
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

1 files changed, 126 insertions, 0 deletions

diff --git a/arch/mips/boot/compressed/decompress.c b/arch/mips/boot/compressed/decompress.c
new file mode 100644
index 000000000000..67330c2f7318
--- /dev/null
+++ b/arch/mips/boot/compressed/decompress.c
@@ -0,0 +1,126 @@
+/*
+ * Misc. bootloader code for many machines.
+ *
+ * Copyright 2001 MontaVista Software Inc.
+ * Author: Matt Porter <mporter@mvista.com> Derived from
+ * arch/ppc/boot/prep/misc.c
+ *
+ * Copyright (C) 2009 Lemote, Inc. & Institute of Computing Technology
+ * Author: Wu Zhangjin <wuzj@lemote.com>
+ *
+ * This program is free software; you can redistribute  it and/or modify it
+ * under  the terms of  the GNU General  Public License as published by the
+ * Free Software Foundation;  either version 2 of the  License, or (at your
+ * option) any later version.
+ */
+
+#include <linux/types.h>
+#include <linux/kernel.h>
+
+#include <asm/addrspace.h>
+
+/* These two variables specify the free mem region
+ * that can be used for temporary malloc area
+ */
+unsigned long free_mem_ptr;
+unsigned long free_mem_end_ptr;
+char *zimage_start;
+
+/* The linker tells us where the image is. */
+extern unsigned char __image_begin, __image_end;
+extern unsigned char __ramdisk_begin, __ramdisk_end;
+unsigned long initrd_size;
+
+/* debug interfaces  */
+extern void puts(const char *s);
+extern void puthex(unsigned long long val);
+
+void error(char *x)
+{
+        puts("\n\n");
+        puts(x);
+        puts("\n\n -- System halted");
+
+        while (1)
+                ;       /* Halt */
+}
+
+/* activate the code for pre-boot environment */
+#define STATIC static
+
+#ifdef CONFIG_KERNEL_GZIP
+void *memcpy(void *dest, const void *src, size_t n)
+{
+        int i;
+        const char *s = src;
+        char *d = dest;
+
+        for (i = 0; i < n; i++)
+                d[i] = s[i];
+        return dest;
+}
+#include "../../../../lib/decompress_inflate.c"
+#endif
+
+#ifdef CONFIG_KERNEL_BZIP2
+void *memset(void *s, int c, size_t n)
+{
+        int i;
+        char *ss = s;
+
+        for (i = 0; i < n; i++)
+                ss[i] = c;
+        return s;
+}
+#include "../../../../lib/decompress_bunzip2.c"
+#endif
+
+#ifdef CONFIG_KERNEL_LZMA
+#include "../../../../lib/decompress_unlzma.c"
+#endif
+
+void decompress_kernel(unsigned long boot_heap_start)
+{
+        int zimage_size;
+
+        /*
+         * We link ourself to an arbitrary low address.  When we run, we
+         * relocate outself to that address.  __image_beign points to
+         * the part of the image where the zImage is. -- Tom
+         */
+        zimage_start = (char *)(unsigned long)(&__image_begin);
+        zimage_size = (unsigned long)(&__image_end) -
+            (unsigned long)(&__image_begin);
+
+        /*
+         * The zImage and initrd will be between start and _end, so they've
+         * already been moved once.  We're good to go now. -- Tom
+         */
+        puts("zimage at:     ");
+        puthex((unsigned long)zimage_start);
+        puts(" ");
+        puthex((unsigned long)(zimage_size + zimage_start));
+        puts("\n");
+
+        if (initrd_size) {
+                puts("initrd at:     ");
+                puthex((unsigned long)(&__ramdisk_begin));
+                puts(" ");
+                puthex((unsigned long)(&__ramdisk_end));
+                puts("\n");
+        }
+
+        /* this area are prepared for mallocing when decompressing */
+        free_mem_ptr = boot_heap_start;
+        free_mem_end_ptr = boot_heap_start + BOOT_HEAP_SIZE;
+
+        /* Display standard Linux/MIPS boot prompt for kernel args */
+        puts("Uncompressing Linux at load address ");
+        puthex(VMLINUX_LOAD_ADDRESS_ULL);
+        puts("\n");
+        /* Decompress the kernel with according algorithm */
+        decompress(zimage_start, zimage_size, 0, 0,
+                   (void *)VMLINUX_LOAD_ADDRESS_ULL, 0, error);
+        /* FIXME: is there a need to flush cache here? */
+        puts("Now, booting the kernel...\n");
+}