/*
   * Memory subsystem initialization for Hexagon
   *
   * Copyright (c) 2010-2013, The Linux Foundation. All rights reserved.
   *
   * This program is free software; you can redistribute it and/or modify
   * it under the terms of the GNU General Public License version 2 and
   * only version 2 as published by the Free Software Foundation.
   *
   * This program is distributed in the hope that it will be useful,
   * but WITHOUT ANY WARRANTY; without even the implied warranty of
   * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   * GNU General Public License for more details.
   *
   * You should have received a copy of the GNU General Public License
   * along with this program; if not, write to the Free Software
   * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
   * 02110-1301, USA.
   */
  
  #include <linux/init.h>
  #include <linux/mm.h>
  #include <linux/bootmem.h>
  #include <asm/atomic.h>
  #include <linux/highmem.h>
  #include <asm/tlb.h>
  #include <asm/sections.h>
  #include <asm/vm_mmu.h>
  
  /*
   * Define a startpg just past the end of the kernel image and a lastpg
   * that corresponds to the end of real or simulated platform memory.
   */
  #define bootmem_startpg (PFN_UP(((unsigned long) _end) - PAGE_OFFSET + PHYS_OFFSET))
  
  unsigned long bootmem_lastpg;	/*  Should be set by platform code  */
  unsigned long __phys_offset;	/*  physical kernel offset >> 12  */
  
  /*  Set as variable to limit PMD copies  */
  int max_kernel_seg = 0x303;
  
  /*  think this should be (page_size-1) the way it's used...*/
  unsigned long zero_page_mask;
  
  /*  indicate pfn's of high memory  */
  unsigned long highstart_pfn, highend_pfn;
  
  DEFINE_PER_CPU(struct mmu_gather, mmu_gathers);
  
  /* Default cache attribute for newly created page tables */
  unsigned long _dflt_cache_att = CACHEDEF;
  
  /*
   * The current "generation" of kernel map, which should not roll
   * over until Hell freezes over.  Actual bound in years needs to be
   * calculated to confirm.
   */
  DEFINE_SPINLOCK(kmap_gen_lock);
  
  /*  checkpatch says don't init this to 0.  */
  unsigned long long kmap_generation;
  
  /*
   * mem_init - initializes memory
   *
   * Frees up bootmem
   * Fixes up more stuff for HIGHMEM
   * Calculates and displays memory available/used
   */
  void __init mem_init(void)
  {
  	/*  No idea where this is actually declared.  Seems to evade LXR.  */
  	free_all_bootmem();
  	mem_init_print_info(NULL);
  
  	/*
  	 *  To-Do:  someone somewhere should wipe out the bootmem map
  	 *  after we're done?
  	 */
  
  	/*
  	 * This can be moved to some more virtual-memory-specific
  	 * initialization hook at some point.  Set the init_mm
  	 * descriptors "context" value to point to the initial
  	 * kernel segment table's physical address.
  	 */
  	init_mm.context.ptbase = __pa(init_mm.pgd);
  }
  
  /*
   * free_initmem - frees memory used by stuff declared with __init
   *
   * Todo:  free pages between __init_begin and __init_end; possibly
   * some devtree related stuff as well.
   */
  void __init_refok free_initmem(void)
  {
  }
  
  /*
   * free_initrd_mem - frees...  initrd memory.
   * @start - start of init memory
   * @end - end of init memory
   *
   * Apparently has to be passed the address of the initrd memory.
   *
   * Wrapped by #ifdef CONFIG_BLKDEV_INITRD
   */
  void free_initrd_mem(unsigned long start, unsigned long end)
  {
  }
  
  void sync_icache_dcache(pte_t pte)
  {
  	unsigned long addr;
  	struct page *page;
  
  	page = pte_page(pte);
  	addr = (unsigned long) page_address(page);
  
  	__vmcache_idsync(addr, PAGE_SIZE);
  }
  
  /*
   * In order to set up page allocator "nodes",
   * somebody has to call free_area_init() for UMA.
   *
   * In this mode, we only have one pg_data_t
   * structure: contig_mem_data.
   */
  void __init paging_init(void)
  {
  	unsigned long zones_sizes[MAX_NR_ZONES] = {0, };
  
  	/*
  	 *  This is not particularly well documented anywhere, but
  	 *  give ZONE_NORMAL all the memory, including the big holes
  	 *  left by the kernel+bootmem_map which are already left as reserved
  	 *  in the bootmem_map; free_area_init should see those bits and
  	 *  adjust accordingly.
  	 */
  
  	zones_sizes[ZONE_NORMAL] = max_low_pfn;
  
  	free_area_init(zones_sizes);  /*  sets up the zonelists and mem_map  */
  
  	/*
  	 * Start of high memory area.  Will probably need something more
  	 * fancy if we...  get more fancy.
  	 */
  	high_memory = (void *)((bootmem_lastpg + 1) << PAGE_SHIFT);
  }
  
  #ifndef DMA_RESERVE
  #define DMA_RESERVE		(4)
  #endif
  
  #define DMA_CHUNKSIZE		(1<<22)
  #define DMA_RESERVED_BYTES	(DMA_RESERVE * DMA_CHUNKSIZE)
  
  /*
   * Pick out the memory size.  We look for mem=size,
   * where size is "size[KkMm]"
   */
  static int __init early_mem(char *p)
  {
  	unsigned long size;
  	char *endp;
  
  	size = memparse(p, &endp);
  
  	bootmem_lastpg = PFN_DOWN(size);
  
  	return 0;
  }
  early_param("mem", early_mem);
  
  size_t hexagon_coherent_pool_size = (size_t) (DMA_RESERVE << 22);
  
  void __init setup_arch_memory(void)
  {
  	int bootmap_size;
  	/*  XXX Todo: this probably should be cleaned up  */
  	u32 *segtable = (u32 *) &swapper_pg_dir[0];
  	u32 *segtable_end;
  
  	/*
  	 * Set up boot memory allocator
  	 *
  	 * The Gorman book also talks about these functions.
  	 * This needs to change for highmem setups.
  	 */
  
  	/*  Prior to this, bootmem_lastpg is actually mem size  */
  	bootmem_lastpg += ARCH_PFN_OFFSET;
  
  	/* Memory size needs to be a multiple of 16M */
  	bootmem_lastpg = PFN_DOWN((bootmem_lastpg << PAGE_SHIFT) &
  		~((BIG_KERNEL_PAGE_SIZE) - 1));
  
  	/*
  	 * Reserve the top DMA_RESERVE bytes of RAM for DMA (uncached)
  	 * memory allocation
  	 */
  
  	max_low_pfn = bootmem_lastpg - PFN_DOWN(DMA_RESERVED_BYTES);
  	min_low_pfn = ARCH_PFN_OFFSET;
  	bootmap_size =  init_bootmem_node(NODE_DATA(0), bootmem_startpg, min_low_pfn, max_low_pfn);
  
  	printk(KERN_INFO "bootmem_startpg:  0x%08lx
  ", bootmem_startpg);
  	printk(KERN_INFO "bootmem_lastpg:  0x%08lx
  ", bootmem_lastpg);
  	printk(KERN_INFO "bootmap_size:  %d
  ", bootmap_size);
  	printk(KERN_INFO "min_low_pfn:  0x%08lx
  ", min_low_pfn);
  	printk(KERN_INFO "max_low_pfn:  0x%08lx
  ", max_low_pfn);
  
  	/*
  	 * The default VM page tables (will be) populated with
  	 * VA=PA+PAGE_OFFSET mapping.  We go in and invalidate entries
  	 * higher than what we have memory for.
  	 */
  
  	/*  this is pointer arithmetic; each entry covers 4MB  */
  	segtable = segtable + (PAGE_OFFSET >> 22);
  
  	/*  this actually only goes to the end of the first gig  */
  	segtable_end = segtable + (1<<(30-22));
  
  	/*
  	 * Move forward to the start of empty pages; take into account
  	 * phys_offset shift.
  	 */
  
  	segtable += (bootmem_lastpg-ARCH_PFN_OFFSET)>>(22-PAGE_SHIFT);
  	{
  		int i;
  
  		for (i = 1 ; i <= DMA_RESERVE ; i++)
  			segtable[-i] = ((segtable[-i] & __HVM_PTE_PGMASK_4MB)
  				| __HVM_PTE_R | __HVM_PTE_W | __HVM_PTE_X
  				| __HEXAGON_C_UNC << 6
  				| __HVM_PDE_S_4MB);
  	}
  
  	printk(KERN_INFO "clearing segtable from %p to %p
  ", segtable,
  		segtable_end);
  	while (segtable < (segtable_end-8))
  		*(segtable++) = __HVM_PDE_S_INVALID;
  	/* stop the pointer at the device I/O 4MB page  */
  
  	printk(KERN_INFO "segtable = %p (should be equal to _K_io_map)
  ",
  		segtable);
  
  #if 0
  	/*  Other half of the early device table from vm_init_segtable. */
  	printk(KERN_INFO "&_K_init_devicetable = 0x%08x
  ",
  		(unsigned long) _K_init_devicetable-PAGE_OFFSET);
  	*segtable = ((u32) (unsigned long) _K_init_devicetable-PAGE_OFFSET) |
  		__HVM_PDE_S_4KB;
  	printk(KERN_INFO "*segtable = 0x%08x
  ", *segtable);
  #endif
  
  	/*
  	 * Free all the memory that wasn't taken up by the bootmap, the DMA
  	 * reserve, or kernel itself.
  	 */
  	free_bootmem(PFN_PHYS(bootmem_startpg) + bootmap_size,
  		     PFN_PHYS(bootmem_lastpg - bootmem_startpg) - bootmap_size -
  		     DMA_RESERVED_BYTES);
  
  	/*
  	 *  The bootmem allocator seemingly just lives to feed memory
  	 *  to the paging system
  	 */
  	printk(KERN_INFO "PAGE_SIZE=%lu
  ", PAGE_SIZE);
  	paging_init();  /*  See Gorman Book, 2.3  */
  
  	/*
  	 *  At this point, the page allocator is kind of initialized, but
  	 *  apparently no pages are available (just like with the bootmem
  	 *  allocator), and need to be freed themselves via mem_init(),
  	 *  which is called by start_kernel() later on in the process
  	 */
  }