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/* SPDX-License-Identifier: copyleft-next-0.3.1 */
/* Copyright 2021 - 2022, Kim Kuparinen < kimi.h.kuparinen@gmail.com > */
/**
* @file dmem.c
* Handle device memory, i.e. anything outside the physical RAM.
*
* \todo Handle NUMA.
*/
#include <kmi/assert.h>
#include <kmi/dmem.h>
/** Region before RAM. */
static struct mem_region_root pre_ram = { 0 };
/** Region after RAM. */
static struct mem_region_root post_ram = { 0 };
stat_t init_devmem(pm_t ram_base, pm_t ram_top)
{
size_t pre_pages = __pages(ram_base);
size_t ram_pages = __pages(ram_top - ram_base);
/* -1 being the effective highest address possible */
size_t post_pages = __pages(-1) - ram_pages - pre_pages;
init_region(&pre_ram, 0, pre_pages, 0);
init_region(&post_ram, ram_top, post_pages, 0);
return OK;
}
/**
* Select between the area before RAM or after RAM, depending on \p addr.
*
* @param addr Physical address of device.
* @return Corresponding device memory region or NULL if \p addr is within RAM.
*/
static struct mem_region_root *__select_region(pm_t addr)
{
if (addr < get_ram_base())
return &pre_ram;
if (addr > (get_ram_base() + get_ram_size()))
return &post_ram;
return NULL;
}
vm_t alloc_devmem(struct tcb *t, pm_t start, size_t bytes, vmflags_t flags)
{
assert(t && is_proc(t));
struct mem_region_root *region = __select_region(start);
if (!region)
return NULL;
vm_t v = alloc_region(region, bytes, &bytes, flags);
if (!v)
return NULL;
if (map_fixed_region(t->proc.vmem, v, start, bytes, flags)) {
unmap_region(t->proc.vmem, v, bytes);
free_region(region, v);
return NULL;
}
return v;
}
stat_t free_devmem(struct tcb *t, vm_t start)
{
assert(t && is_proc(t));
pm_t addr = 0;
stat_vpage(t->proc.vmem, start, &addr, NULL, NULL);
struct mem_region_root *region = __select_region((pm_t)__pa(addr));
if (!region)
return ERR_INVAL;
struct mem_region *m = find_used_region(region, start);
if (!m)
return ERR_NF;
vm_t base = __addr(m->start);
vm_t end = __addr(m->end);
size_t size = end - base;
unmap_fixed_region(t->proc.vmem, base, size);
free_region(region, base);
return OK;
}
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