/*
   * arch/alpha/boot/bootp.c
   *
   * Copyright (C) 1997 Jay Estabrook
   *
   * This file is used for creating a bootp file for the Linux/AXP kernel
   *
   * based significantly on the arch/alpha/boot/main.c of Linus Torvalds
   */
  #include <linux/kernel.h>
  #include <linux/slab.h>
  #include <linux/string.h>
  #include <generated/utsrelease.h>
  #include <linux/mm.h>
  
  #include <asm/console.h>
  #include <asm/hwrpb.h>
  #include <asm/pgtable.h>
  #include <asm/io.h>
  
  #include <stdarg.h>
  
  #include "ksize.h"
  
  extern unsigned long switch_to_osf_pal(unsigned long nr,
  	struct pcb_struct * pcb_va, struct pcb_struct * pcb_pa,
  	unsigned long *vptb);
  
  extern void move_stack(unsigned long new_stack);
  
  struct hwrpb_struct *hwrpb = INIT_HWRPB;
  static struct pcb_struct pcb_va[1];
  
  /*
   * Find a physical address of a virtual object..
   *
   * This is easy using the virtual page table address.
   */
  
  static inline void *
  find_pa(unsigned long *vptb, void *ptr)
  {
  	unsigned long address = (unsigned long) ptr;
  	unsigned long result;
  
  	result = vptb[address >> 13];
  	result >>= 32;
  	result <<= 13;
  	result |= address & 0x1fff;
  	return (void *) result;
  }	
  
  /*
   * This function moves into OSF/1 pal-code, and has a temporary
   * PCB for that. The kernel proper should replace this PCB with
   * the real one as soon as possible.
   *
   * The page table muckery in here depends on the fact that the boot
   * code has the L1 page table identity-map itself in the second PTE
   * in the L1 page table. Thus the L1-page is virtually addressable
   * itself (through three levels) at virtual address 0x200802000.
   */
  
  #define VPTB	((unsigned long *) 0x200000000)
  #define L1	((unsigned long *) 0x200802000)
  
  void
  pal_init(void)
  {
  	unsigned long i, rev;
  	struct percpu_struct * percpu;
  	struct pcb_struct * pcb_pa;
  
  	/* Create the dummy PCB.  */
  	pcb_va->ksp = 0;
  	pcb_va->usp = 0;
  	pcb_va->ptbr = L1[1] >> 32;
  	pcb_va->asn = 0;
  	pcb_va->pcc = 0;
  	pcb_va->unique = 0;
  	pcb_va->flags = 1;
  	pcb_va->res1 = 0;
  	pcb_va->res2 = 0;
  	pcb_pa = find_pa(VPTB, pcb_va);
  
  	/*
  	 * a0 = 2 (OSF)
  	 * a1 = return address, but we give the asm the vaddr of the PCB
  	 * a2 = physical addr of PCB
  	 * a3 = new virtual page table pointer
  	 * a4 = KSP (but the asm sets it)
  	 */
  	srm_printk("Switching to OSF PAL-code .. ");
  
  	i = switch_to_osf_pal(2, pcb_va, pcb_pa, VPTB);
  	if (i) {
  		srm_printk("failed, code %ld
  ", i);
  		__halt();
  	}
  
  	percpu = (struct percpu_struct *)
  		(INIT_HWRPB->processor_offset + (unsigned long) INIT_HWRPB);
  	rev = percpu->pal_revision = percpu->palcode_avail[2];
  
  	srm_printk("Ok (rev %lx)
  ", rev);
  
  	tbia(); /* do it directly in case we are SMP */
  }
  
  static inline void
  load(unsigned long dst, unsigned long src, unsigned long count)
  {
  	memcpy((void *)dst, (void *)src, count);
  }
  
  /*
   * Start the kernel.
   */
  static inline void
  runkernel(void)
  {
  	__asm__ __volatile__(
  		"bis %0,%0,$27
  \t"
  		"jmp ($27)"
  		: /* no outputs: it doesn't even return */
  		: "r" (START_ADDR));
  }
  
  extern char _end;
  #define KERNEL_ORIGIN \
  	((((unsigned long)&_end) + 511) & ~511)
  
  void
  start_kernel(void)
  {
  	/*
  	 * Note that this crufty stuff with static and envval
  	 * and envbuf is because:
  	 *
  	 * 1. Frequently, the stack is short, and we don't want to overrun;
  	 * 2. Frequently the stack is where we are going to copy the kernel to;
  	 * 3. A certain SRM console required the GET_ENV output to stack.
  	 *    ??? A comment in the aboot sources indicates that the GET_ENV
  	 *    destination must be quadword aligned.  Might this explain the
  	 *    behaviour, rather than requiring output to the stack, which
  	 *    seems rather far-fetched.
  	 */
  	static long nbytes;
  	static char envval[256] __attribute__((aligned(8)));
  	static unsigned long initrd_start;
  
  	srm_printk("Linux/AXP bootp loader for Linux " UTS_RELEASE "
  ");
  	if (INIT_HWRPB->pagesize != 8192) {
  		srm_printk("Expected 8kB pages, got %ldkB
  ",
  		           INIT_HWRPB->pagesize >> 10);
  		return;
  	}
  	if (INIT_HWRPB->vptb != (unsigned long) VPTB) {
  		srm_printk("Expected vptb at %p, got %p
  ",
  			   VPTB, (void *)INIT_HWRPB->vptb);
  		return;
  	}
  	pal_init();
  
  	/* The initrd must be page-aligned.  See below for the 
  	   cause of the magic number 5.  */
  	initrd_start = ((START_ADDR + 5*KERNEL_SIZE + PAGE_SIZE) |
  			(PAGE_SIZE-1)) + 1;
  #ifdef INITRD_IMAGE_SIZE
  	srm_printk("Initrd positioned at %#lx
  ", initrd_start);
  #endif
  
  	/*
  	 * Move the stack to a safe place to ensure it won't be
  	 * overwritten by kernel image.
  	 */
  	move_stack(initrd_start - PAGE_SIZE);
  
  	nbytes = callback_getenv(ENV_BOOTED_OSFLAGS, envval, sizeof(envval));
  	if (nbytes < 0 || nbytes >= sizeof(envval)) {
  		nbytes = 0;
  	}
  	envval[nbytes] = '\0';
  	srm_printk("Loading the kernel...'%s'
  ", envval);
  
  	/* NOTE: *no* callbacks or printouts from here on out!!! */
  
  	/* This is a hack, as some consoles seem to get virtual 20000000 (ie
  	 * where the SRM console puts the kernel bootp image) memory
  	 * overlapping physical memory where the kernel wants to be put,
  	 * which causes real problems when attempting to copy the former to
  	 * the latter... :-(
  	 *
  	 * So, we first move the kernel virtual-to-physical way above where
  	 * we physically want the kernel to end up, then copy it from there
  	 * to its final resting place... ;-}
  	 *
  	 * Sigh...  */
  
  #ifdef INITRD_IMAGE_SIZE
  	load(initrd_start, KERNEL_ORIGIN+KERNEL_SIZE, INITRD_IMAGE_SIZE);
  #endif
          load(START_ADDR+(4*KERNEL_SIZE), KERNEL_ORIGIN, KERNEL_SIZE);
          load(START_ADDR, START_ADDR+(4*KERNEL_SIZE), KERNEL_SIZE);
  
  	memset((char*)ZERO_PGE, 0, PAGE_SIZE);
  	strcpy((char*)ZERO_PGE, envval);
  #ifdef INITRD_IMAGE_SIZE
  	((long *)(ZERO_PGE+256))[0] = initrd_start;
  	((long *)(ZERO_PGE+256))[1] = INITRD_IMAGE_SIZE;
  #endif
  
  	runkernel();
  }