/*
   * Routines for doing kexec-based kdump.
   *
   * Copyright (C) 2005, IBM Corp.
   *
   * Created by: Michael Ellerman
   *
   * This source code is licensed under the GNU General Public License,
   * Version 2.  See the file COPYING for more details.
   */
  
  #undef DEBUG

  #include <linux/crash_dump.h>
  #include <linux/bootmem.h>

  #include <linux/memblock.h>

  #include <asm/code-patching.h>

  #include <asm/kdump.h>

  #include <asm/prom.h>

  #include <asm/firmware.h>

  #include <asm/uaccess.h>

  #include <asm/rtas.h>

  
  #ifdef DEBUG
  #include <asm/udbg.h>
  #define DBG(fmt...) udbg_printf(fmt)
  #else
  #define DBG(fmt...)
  #endif

  #ifndef CONFIG_NONSTATIC_KERNEL

  void __init reserve_kdump_trampoline(void)

  {

  	memblock_reserve(0, KDUMP_RESERVE_LIMIT);

  }

  static void __init create_trampoline(unsigned long addr)
  {

  	unsigned int *p = (unsigned int *)addr;

  	/* The maximum range of a single instruction branch, is the current
  	 * instruction's address + (32 MB - 4) bytes. For the trampoline we
  	 * need to branch to current address + 32 MB. So we insert a nop at
  	 * the trampoline address, then the next instruction (+ 4 bytes)
  	 * does a branch to (32 MB - 4). The net effect is that when we
  	 * branch to "addr" we jump to ("addr" + 32 MB). Although it requires
  	 * two instructions it doesn't require any registers.
  	 */

  	patch_instruction(p, PPC_INST_NOP);

  	patch_branch(++p, addr + PHYSICAL_START, 0);

  }

  void __init setup_kdump_trampoline(void)

  {
  	unsigned long i;

  	DBG(" -> setup_kdump_trampoline()
  ");

  
  	for (i = KDUMP_TRAMPOLINE_START; i < KDUMP_TRAMPOLINE_END; i += 8) {
  		create_trampoline(i);
  	}

  #ifdef CONFIG_PPC_PSERIES

  	create_trampoline(__pa(system_reset_fwnmi) - PHYSICAL_START);
  	create_trampoline(__pa(machine_check_fwnmi) - PHYSICAL_START);

  #endif /* CONFIG_PPC_PSERIES */

  	DBG(" <- setup_kdump_trampoline()
  ");

  }

  #endif /* CONFIG_NONSTATIC_KERNEL */

  static int __init parse_savemaxmem(char *p)
  {
  	if (p)
  		saved_max_pfn = (memparse(p, &p) >> PAGE_SHIFT) - 1;

  	return 1;

  }
  __setup("savemaxmem=", parse_savemaxmem);

  
  static size_t copy_oldmem_vaddr(void *vaddr, char *buf, size_t csize,
                                 unsigned long offset, int userbuf)
  {
  	if (userbuf) {
  		if (copy_to_user((char __user *)buf, (vaddr + offset), csize))
  			return -EFAULT;
  	} else
  		memcpy(buf, (vaddr + offset), csize);
  
  	return csize;
  }

  /**

   * copy_oldmem_page - copy one page from "oldmem"
   * @pfn: page frame number to be copied
   * @buf: target memory address for the copy; this can be in kernel address
   *      space or user address space (see @userbuf)
   * @csize: number of bytes to copy
   * @offset: offset in bytes into the page (based on pfn) to begin the copy
   * @userbuf: if set, @buf is in user address space, use copy_to_user(),
   *      otherwise @buf is in kernel address space, use memcpy().
   *
   * Copy a page from "oldmem". For this page, there is no pte mapped
   * in the current kernel. We stitch up a pte, similar to kmap_atomic.
   */
  ssize_t copy_oldmem_page(unsigned long pfn, char *buf,
  			size_t csize, unsigned long offset, int userbuf)
  {
  	void  *vaddr;
  
  	if (!csize)
  		return 0;

  	csize = min_t(size_t, csize, PAGE_SIZE);

  	if ((min_low_pfn < pfn) && (pfn < max_pfn)) {

  		vaddr = __va(pfn << PAGE_SHIFT);
  		csize = copy_oldmem_vaddr(vaddr, buf, csize, offset, userbuf);
  	} else {
  		vaddr = __ioremap(pfn << PAGE_SHIFT, PAGE_SIZE, 0);
  		csize = copy_oldmem_vaddr(vaddr, buf, csize, offset, userbuf);
  		iounmap(vaddr);
  	}

  	return csize;
  }

  
  #ifdef CONFIG_PPC_RTAS
  /*
   * The crashkernel region will almost always overlap the RTAS region, so
   * we have to be careful when shrinking the crashkernel region.
   */
  void crash_free_reserved_phys_range(unsigned long begin, unsigned long end)
  {
  	unsigned long addr;
  	const u32 *basep, *sizep;
  	unsigned int rtas_start = 0, rtas_end = 0;
  
  	basep = of_get_property(rtas.dev, "linux,rtas-base", NULL);
  	sizep = of_get_property(rtas.dev, "rtas-size", NULL);
  
  	if (basep && sizep) {
  		rtas_start = *basep;
  		rtas_end = *basep + *sizep;
  	}
  
  	for (addr = begin; addr < end; addr += PAGE_SIZE) {
  		/* Does this page overlap with the RTAS region? */
  		if (addr <= rtas_end && ((addr + PAGE_SIZE) > rtas_start))
  			continue;
  
  		ClearPageReserved(pfn_to_page(addr >> PAGE_SHIFT));
  		init_page_count(pfn_to_page(addr >> PAGE_SHIFT));
  		free_page((unsigned long)__va(addr));
  		totalram_pages++;
  	}
  }
  #endif