/* Copyright (C) 2004  David Decotigny
    Copyright (C) 2000  The KOS Team
 
    This program is free software; you can redistribute it and/or
    modify it under the terms of the GNU General Public License
    as published by the Free Software Foundation; either version 2
    of the License, or (at your option) any later version.
    
    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., 59 Temple Place - Suite 330, Boston, MA 02111-1307,
    USA. 
 */
 #ifndef _SOS_PHYSMEM_H_
 #define _SOS_PHYSMEM_H_
 
 /**
  * @file physmem.h
  *
  * Physical pages of memory
  */
 
 #include <sos/errno.h>
 #include <sos/types.h>
 #include <sos/macros.h>
 
 /** The size of a physical page (arch-dependent) */
 #define SOS_PAGE_SIZE  (4*1024)
 
 /** The corresponding shift */
 #define SOS_PAGE_SHIFT 12 /* 4 kB = 2^12 B */
 
 /** The corresponding mask */
 #define SOS_PAGE_MASK  ((1<<12) - 1)
 
 #define SOS_PAGE_ALIGN_INF(val)  \
   SOS_ALIGN_INF((val), SOS_PAGE_SIZE)
 #define SOS_PAGE_ALIGN_SUP(val)  \
   SOS_ALIGN_SUP((val), SOS_PAGE_SIZE)
 #define SOS_IS_PAGE_ALIGNED(val) \
   SOS_IS_ALIGNED((val), SOS_PAGE_SIZE)
 
 /**
  * This is the reserved physical interval for the x86 video memory and
  * BIOS area. In physmem.c, we have to mark this area as "nonfree" in
  * order to prevent from allocating it. And in paging.c, we'd better
  * map it in virtual space if we really want to be able to print to
  * the screen (for debugging purpose, at least): for this, the
  * simplest is to identity-map this area in virtual space (note
  * however that this mapping could also be non-identical).
  */
 #define BIOS_N_VIDEO_START 0xa0000
 #define BIOS_N_VIDEO_END   0x100000
 
 
 /**
  * Initialize the physical memory subsystem, for the physical area [0,
  * ram_size). This routine takes into account the BIOS and video
  * areas, to prevent them from future allocations.
  *
  * @param ram_size The size of the RAM that will be managed by this subsystem
  *
  * @param kernel_core_base The lowest address for which the kernel
  * assumes identity mapping (ie virtual address == physical address)
  * will be stored here
  *
  * @param kernel_core_top The top address for which the kernel
  * assumes identity mapping (ie virtual address == physical address)
  * will be stored here
  */
 sos_ret_t sos_physmem_subsystem_setup(sos_size_t ram_size,
                                       /* out */sos_paddr_t *kernel_core_base,
                                       /* out */sos_paddr_t *kernel_core_top);
 
 
 /**
  * Retrieve the total number of pages, and the number of free pages
  *
  * @note both parameters may be NULL
  */
 sos_ret_t sos_physmem_get_state(/* out */sos_count_t *total_ppages,
                                 /* out */sos_count_t *nonfree_ppages);
 
 
 /**
  * Get a free page.
  *
  * @return The (physical) address of the (physical) page allocated, or
  * NULL when none currently available.
  *
  * @param can_block TRUE if the function is allowed to block
  * @note The page returned has a reference count equal to 1.
  */
 sos_paddr_t sos_physmem_ref_physpage_new(sos_bool_t can_block);
 
 
 /**
  * Increment the reference count of a given physical page. Useful for
  * VM code which tries to map a precise physical address.
  *
  * @param ppage_paddr Physical address of the page (MUST be page-aligned)
  *
  * @return TRUE when the page was previously referenced, FALSE when
  * the page was previously unreferenced, <0 when the page address is
  * invalid.
  */
 sos_ret_t sos_physmem_ref_physpage_at(sos_paddr_t ppage_paddr);
 
 
 /**
  * Decrement the reference count of the given physical page. When the
  * reference count of the page reaches 0, the page is marked free, ie
  * is available for future sos_physmem_ref_physpage_new()
  *
  * @param ppage_paddr Physical address of the page (MUST be page-aligned)
  *
  * @return FALSE when the page is still referenced, TRUE when the page
  * is now unreferenced, <0 when the page address is invalid
  */
 sos_ret_t sos_physmem_unref_physpage(sos_paddr_t ppage_paddr);
 
 
 /**
  * Return the reference count of the given page
  *
  * @return >= 0 (the referebce count of the page) if the physical
  * address is valid, or an error status
  */
 sos_ret_t sos_physmem_get_physpage_refcount(sos_paddr_t ppage_paddr);
 
 
 
 /*
  * In some cases (Page Tables on x86 for example), the physical pages
  * might contain a set of slots available for "allocation" (x86
  * example: a PT contains a set of PTE). We provide here a set of
  * functions to manage a per-page additional counter that holds this
  * number of slots currently in use in the page.
  *
  * A newly allocated physical page has a occupation count of 0.
  *
  * The management of this counter is up to the subsystem that manages
  * the page (mainly: paging), however a simple set of rules applies:
  *   - it can only be incremented/decremented if the page is referenced
  *   - when it reaches 0, no automatic action is undertaken
  * The first rule means in particular that a page whose reference
  * count reaches 0 (=> being freed) cannot have a occupation_cnt
  * value > 0 ! The system will be HALTED if this ever happens
  */
 
 
 /**
  * Increment the occupation count of the given physical page.
  *
  * @param ppage_paddr Physical address of the page (MUST be page-aligned)
  *
  * @return TRUE when the occupation count was previously NON-ZERO, FALSE
  * when this occupation count was 0, <0 when the page address is invalid.
  *
  * @note the page MUST be marked as REFERENCED by somebody !
  */
 sos_ret_t sos_physmem_inc_physpage_occupation(sos_paddr_t ppage_paddr);
 
 
 /**
  * Decrement the occupation count of the given physical page.
  *
  * @param ppage_paddr Physical address of the page (MUST be page-aligned)
  *
  * @return FALSE when the occupation count is still NON-ZERO, TRUE when the
  * page now is ZERO, <0 when the page address is invalid
  *
  * @note the page MUST be marked as REFERENCED by somebody !
  */
 sos_ret_t sos_physmem_dec_physpage_occupation(sos_paddr_t ppage_paddr);
 
 
 #include <sos/kmem_vmm.h>
 
 /**
  * Return the kernel memory allocation range associated with the given
  * physical page, or NULL when page has no associated range
  *
  * @param ppage_paddr Physical address of the page (MUST be page-aligned)
  */
 struct sos_kmem_range* sos_physmem_get_kmem_range(sos_paddr_t ppage_paddr);
 
 
 /**
  * Set the kernel memory allocation range associated to the given
  * physical page.
  *
  * @param ppage_paddr Physical address of the page (MUST be page-aligned)
  *
  * @return error if page is invalid
  */
 sos_ret_t sos_physmem_set_kmem_range(sos_paddr_t ppage_paddr,
                                      struct sos_kmem_range *range);
 
 #endif /* _SOS_PHYSMEM_H_ */