/* linux/arch/arm/plat-s3c/pm-check.c
   *  originally in linux/arch/arm/plat-s3c24xx/pm.c
   *
   * Copyright (c) 2004-2008 Simtec Electronics
   *	http://armlinux.simtec.co.uk
   *	Ben Dooks <ben@simtec.co.uk>
   *
   * S3C Power Mangament - suspend/resume memory corruptiuon check.
   *
   * This program is free software; you can redistribute it and/or modify
   * it under the terms of the GNU General Public License version 2 as
   * published by the Free Software Foundation.
  */
  
  #include <linux/kernel.h>
  #include <linux/suspend.h>
  #include <linux/init.h>
  #include <linux/crc32.h>
  #include <linux/ioport.h>
  #include <linux/slab.h>
  
  #include <plat/pm.h>
  
  #if CONFIG_SAMSUNG_PM_CHECK_CHUNKSIZE < 1
  #error CONFIG_SAMSUNG_PM_CHECK_CHUNKSIZE must be a positive non-zero value
  #endif
  
  /* suspend checking code...
   *
   * this next area does a set of crc checks over all the installed
   * memory, so the system can verify if the resume was ok.
   *
   * CONFIG_SAMSUNG_PM_CHECK_CHUNKSIZE defines the block-size for the CRC,
   * increasing it will mean that the area corrupted will be less easy to spot,
   * and reducing the size will cause the CRC save area to grow
  */
  
  #define CHECK_CHUNKSIZE (CONFIG_SAMSUNG_PM_CHECK_CHUNKSIZE * 1024)
  
  static u32 crc_size;	/* size needed for the crc block */
  static u32 *crcs;	/* allocated over suspend/resume */
  
  typedef u32 *(run_fn_t)(struct resource *ptr, u32 *arg);
  
  /* s3c_pm_run_res
   *
   * go through the given resource list, and look for system ram
  */
  
  static void s3c_pm_run_res(struct resource *ptr, run_fn_t fn, u32 *arg)
  {
  	while (ptr != NULL) {
  		if (ptr->child != NULL)
  			s3c_pm_run_res(ptr->child, fn, arg);
  
  		if ((ptr->flags & IORESOURCE_MEM) &&
  		    strcmp(ptr->name, "System RAM") == 0) {
  			S3C_PMDBG("Found system RAM at %08lx..%08lx
  ",
  				  (unsigned long)ptr->start,
  				  (unsigned long)ptr->end);
  			arg = (fn)(ptr, arg);
  		}
  
  		ptr = ptr->sibling;
  	}
  }
  
  static void s3c_pm_run_sysram(run_fn_t fn, u32 *arg)
  {
  	s3c_pm_run_res(&iomem_resource, fn, arg);
  }
  
  static u32 *s3c_pm_countram(struct resource *res, u32 *val)
  {
  	u32 size = (u32)resource_size(res);
  
  	size += CHECK_CHUNKSIZE-1;
  	size /= CHECK_CHUNKSIZE;
  
  	S3C_PMDBG("Area %08lx..%08lx, %d blocks
  ",
  		  (unsigned long)res->start, (unsigned long)res->end, size);
  
  	*val += size * sizeof(u32);
  	return val;
  }
  
  /* s3c_pm_prepare_check
   *
   * prepare the necessary information for creating the CRCs. This
   * must be done before the final save, as it will require memory
   * allocating, and thus touching bits of the kernel we do not
   * know about.
  */
  
  void s3c_pm_check_prepare(void)
  {
  	crc_size = 0;
  
  	s3c_pm_run_sysram(s3c_pm_countram, &crc_size);
  
  	S3C_PMDBG("s3c_pm_prepare_check: %u checks needed
  ", crc_size);
  
  	crcs = kmalloc(crc_size+4, GFP_KERNEL);
  	if (crcs == NULL)
  		printk(KERN_ERR "Cannot allocated CRC save area
  ");
  }
  
  static u32 *s3c_pm_makecheck(struct resource *res, u32 *val)
  {
  	unsigned long addr, left;
  
  	for (addr = res->start; addr < res->end;
  	     addr += CHECK_CHUNKSIZE) {
  		left = res->end - addr;
  
  		if (left > CHECK_CHUNKSIZE)
  			left = CHECK_CHUNKSIZE;
  
  		*val = crc32_le(~0, phys_to_virt(addr), left);
  		val++;
  	}
  
  	return val;
  }
  
  /* s3c_pm_check_store
   *
   * compute the CRC values for the memory blocks before the final
   * sleep.
  */
  
  void s3c_pm_check_store(void)
  {
  	if (crcs != NULL)
  		s3c_pm_run_sysram(s3c_pm_makecheck, crcs);
  }
  
  /* in_region
   *
   * return TRUE if the area defined by ptr..ptr+size contains the
   * what..what+whatsz
  */
  
  static inline int in_region(void *ptr, int size, void *what, size_t whatsz)
  {
  	if ((what+whatsz) < ptr)
  		return 0;
  
  	if (what > (ptr+size))
  		return 0;
  
  	return 1;
  }
  
  /**
   * s3c_pm_runcheck() - helper to check a resource on restore.
   * @res: The resource to check
   * @vak: Pointer to list of CRC32 values to check.
   *
   * Called from the s3c_pm_check_restore() via s3c_pm_run_sysram(), this
   * function runs the given memory resource checking it against the stored
   * CRC to ensure that memory is restored. The function tries to skip as
   * many of the areas used during the suspend process.
   */
  static u32 *s3c_pm_runcheck(struct resource *res, u32 *val)
  {
  	unsigned long addr;
  	unsigned long left;
  	void *stkpage;
  	void *ptr;
  	u32 calc;
  
  	stkpage = (void *)((u32)&calc & ~PAGE_MASK);
  
  	for (addr = res->start; addr < res->end;
  	     addr += CHECK_CHUNKSIZE) {
  		left = res->end - addr;
  
  		if (left > CHECK_CHUNKSIZE)
  			left = CHECK_CHUNKSIZE;
  
  		ptr = phys_to_virt(addr);
  
  		if (in_region(ptr, left, stkpage, 4096)) {
  			S3C_PMDBG("skipping %08lx, has stack in
  ", addr);
  			goto skip_check;
  		}
  
  		if (in_region(ptr, left, crcs, crc_size)) {
  			S3C_PMDBG("skipping %08lx, has crc block in
  ", addr);
  			goto skip_check;
  		}
  
  		/* calculate and check the checksum */
  
  		calc = crc32_le(~0, ptr, left);
  		if (calc != *val) {
  			printk(KERN_ERR "Restore CRC error at "
  			       "%08lx (%08x vs %08x)
  ", addr, calc, *val);
  
  			S3C_PMDBG("Restore CRC error at %08lx (%08x vs %08x)
  ",
  			    addr, calc, *val);
  		}
  
  	skip_check:
  		val++;
  	}
  
  	return val;
  }
  
  /**
   * s3c_pm_check_restore() - memory check called on resume
   *
   * check the CRCs after the restore event and free the memory used
   * to hold them
  */
  void s3c_pm_check_restore(void)
  {
  	if (crcs != NULL)
  		s3c_pm_run_sysram(s3c_pm_runcheck, crcs);
  }
  
  /**
   * s3c_pm_check_cleanup() - free memory resources
   *
   * Free the resources that where allocated by the suspend
   * memory check code. We do this separately from the
   * s3c_pm_check_restore() function as we cannot call any
   * functions that might sleep during that resume.
   */
  void s3c_pm_check_cleanup(void)
  {
  	kfree(crcs);
  	crcs = NULL;
  }