[PATCH] powerpc: Add back support for booting from BootX (#2)

ARCH=powerpc couldn't boot from BootX as it uses a "different" way of
getting in the kernel. This patch adds the necessary trampolines,
creating a flattened device-tree from the tree passed from MacOS, and
initializing the btext engine early for really-early debugging.
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: Paul Mackerras <paulus@samba.org>

arch/powerpc/kernel/head_32.S

@@ -125,6 +125,19 @@ __start:
 	bl	prom_init
 	trap
 
+/*
+ * Check for BootX signature when supporting PowerMac and branch to
+ * appropriate trampoline if it's present
+ */
+#ifdef CONFIG_PPC_PMAC
+1:	lis	r31,0x426f
+	ori	r31,r31,0x6f58
+	cmpw	0,r3,r31
+	bne	1f
+	bl	bootx_init
+	trap
+#endif /* CONFIG_PPC_PMAC */
+
 1:	mr	r31,r3			/* save parameters */
 	mr	r30,r4
 	li	r24,0			/* cpu # */

arch/powerpc/platforms/powermac/Makefile

+CFLAGS_bootx_init.o  		+= -fPIC
+
 obj-y				+= pic.o setup.o time.o feature.o pci.o \
 				   sleep.o low_i2c.o cache.o
 obj-$(CONFIG_PMAC_BACKLIGHT)	+= backlight.o
@@ -6,5 +8,6 @@ obj-$(CONFIG_CPU_FREQ_PMAC64)	+= cpufreq_64.o
 obj-$(CONFIG_NVRAM)		+= nvram.o
 # ppc64 pmac doesn't define CONFIG_NVRAM but needs nvram stuff
 obj-$(CONFIG_PPC64)		+= nvram.o
+obj-$(CONFIG_PPC32)		+= bootx_init.o
 obj-$(CONFIG_SMP)		+= smp.o
 obj-$(CONFIG_PPC_MERGE)		+= udbg_scc.o udbg_adb.o

include/asm-powerpc/bootx.h

+/*
+ * This file describes the structure passed from the BootX application
+ * (for MacOS) when it is used to boot Linux.
+ *
+ * Written by Benjamin Herrenschmidt.
+ */
+
+
+#ifndef __ASM_BOOTX_H__
+#define __ASM_BOOTX_H__
+
+#ifdef macintosh
+#include <Types.h>
+#include "linux_type_defs.h"
+#endif
+
+#ifdef macintosh
+/* All this requires PowerPC alignment */
+#pragma options align=power
+#endif
+
+/* On kernel entry:
+ *
+ * r3 = 0x426f6f58    ('BooX')
+ * r4 = pointer to boot_infos
+ * r5 = NULL
+ *
+ * Data and instruction translation disabled, interrupts
+ * disabled, kernel loaded at physical 0x00000000 on PCI
+ * machines (will be different on NuBus).
+ */
+
+#define BOOT_INFO_VERSION               5
+#define BOOT_INFO_COMPATIBLE_VERSION    1
+
+/* Bit in the architecture flag mask. More to be defined in
+   future versions. Note that either BOOT_ARCH_PCI or
+   BOOT_ARCH_NUBUS is set. The other BOOT_ARCH_NUBUS_xxx are
+   set additionally when BOOT_ARCH_NUBUS is set.
+ */
+#define BOOT_ARCH_PCI                   0x00000001UL
+#define BOOT_ARCH_NUBUS                 0x00000002UL
+#define BOOT_ARCH_NUBUS_PDM             0x00000010UL
+#define BOOT_ARCH_NUBUS_PERFORMA        0x00000020UL
+#define BOOT_ARCH_NUBUS_POWERBOOK       0x00000040UL
+
+/*  Maximum number of ranges in phys memory map */
+#define MAX_MEM_MAP_SIZE				26
+
+/* This is the format of an element in the physical memory map. Note that
+   the map is optional and current BootX will only build it for pre-PCI
+   machines */
+typedef struct boot_info_map_entry
+{
+    __u32       physAddr;                /* Physical starting address */
+    __u32       size;                    /* Size in bytes */
+} boot_info_map_entry_t;
+
+
+/* Here are the boot informations that are passed to the bootstrap
+ * Note that the kernel arguments and the device tree are appended
+ * at the end of this structure. */
+typedef struct boot_infos
+{
+    /* Version of this structure */
+    __u32       version;
+    /* backward compatible down to version: */
+    __u32       compatible_version;
+
+    /* NEW (vers. 2) this holds the current _logical_ base addr of
+       the frame buffer (for use by early boot message) */
+    __u8*       logicalDisplayBase;
+
+    /* NEW (vers. 4) Apple's machine identification */
+    __u32       machineID;
+
+    /* NEW (vers. 4) Detected hw architecture */
+    __u32       architecture;
+
+    /* The device tree (internal addresses relative to the beginning of the tree,
+     * device tree offset relative to the beginning of this structure).
+     * On pre-PCI macintosh (BOOT_ARCH_PCI bit set to 0 in architecture), this
+     * field is 0.
+     */
+    __u32       deviceTreeOffset;        /* Device tree offset */
+    __u32       deviceTreeSize;          /* Size of the device tree */
+
+    /* Some infos about the current MacOS display */
+    __u32       dispDeviceRect[4];       /* left,top,right,bottom */
+    __u32       dispDeviceDepth;         /* (8, 16 or 32) */
+    __u8*       dispDeviceBase;          /* base address (physical) */
+    __u32       dispDeviceRowBytes;      /* rowbytes (in bytes) */
+    __u32       dispDeviceColorsOffset;  /* Colormap (8 bits only) or 0 (*) */
+    /* Optional offset in the registry to the current
+     * MacOS display. (Can be 0 when not detected) */
+     __u32      dispDeviceRegEntryOffset;
+
+    /* Optional pointer to boot ramdisk (offset from this structure) */
+    __u32       ramDisk;
+    __u32       ramDiskSize;             /* size of ramdisk image */
+
+    /* Kernel command line arguments (offset from this structure) */
+    __u32       kernelParamsOffset;
+
+    /* ALL BELOW NEW (vers. 4) */
+
+    /* This defines the physical memory. Valid with BOOT_ARCH_NUBUS flag
+       (non-PCI) only. On PCI, memory is contiguous and it's size is in the
+       device-tree. */
+    boot_info_map_entry_t
+    	        physMemoryMap[MAX_MEM_MAP_SIZE]; /* Where the phys memory is */
+    __u32       physMemoryMapSize;               /* How many entries in map */
+
+
+    /* The framebuffer size (optional, currently 0) */
+    __u32       frameBufferSize;         /* Represents a max size, can be 0. */
+
+    /* NEW (vers. 5) */
+
+    /* Total params size (args + colormap + device tree + ramdisk) */
+    __u32       totalParamsSize;
+
+} boot_infos_t;
+
+/* (*) The format of the colormap is 256 * 3 * 2 bytes. Each color index
+ * is represented by 3 short words containing a 16 bits (unsigned) color
+ * component. Later versions may contain the gamma table for direct-color
+ * devices here.
+ */
+#define BOOTX_COLORTABLE_SIZE    (256UL*3UL*2UL)
+
+/* BootX passes the device-tree using a format that comes from earlier
+ * ppc32 kernels. This used to match what is in prom.h, but not anymore
+ * so we now define it here
+ */
+struct bootx_dt_prop {
+	u32	name;
+	int	length;
+	u32	value;
+	u32	next;
+};
+
+struct bootx_dt_node {
+	u32	unused0;
+	u32	unused1;
+	u32	phandle;	/* not really available */
+	u32	unused2;
+	u32	unused3;
+	u32	unused4;
+	u32	unused5;
+	u32	full_name;
+	u32	properties;
+	u32	parent;
+	u32	child;
+	u32	sibling;
+	u32	next;
+	u32	allnext;
+};
+
+extern void bootx_init(unsigned long r4, unsigned long phys);
+
+#ifdef macintosh
+#pragma options align=reset
+#endif
+
+#endif