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+/* 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 "used" 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
+ */
+sos_ret_t sos_physmem_get_state(/* out */sos_count_t *total_ppages,
+				/* out */sos_count_t *used_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 in use, FALSE when the
+ * page was previously in the free list, <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 this
+ * reference count reaches 0, the page is marked free, ie is available
+ * for future sos_physmem_get_physpage()
+ *
+ * @param ppage_paddr Physical address of the page (MUST be page-aligned)
+ *
+ * @return FALSE when the page is still in use, 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);
+
+
+#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_ */