intmem.c

linux内核源码

/*
 * Simple allocator for internal RAM in ETRAX FS
 *
 * Copyright (c) 2004 Axis Communications AB.
 */

#include <linux/list.h>
#include <linux/slab.h>
#include <asm/io.h>
#include <asm/arch/memmap.h>

#define STATUS_FREE 0
#define STATUS_ALLOCATED 1

struct intmem_allocation {
	struct list_head entry;
	unsigned int size;
	unsigned offset;
	char status;
};


static struct list_head intmem_allocations;
static void* intmem_virtual;

static void crisv32_intmem_init(void)
{
	static int initiated = 0;
	if (!initiated) {
		struct intmem_allocation* alloc =
		  (struct intmem_allocation*)kmalloc(sizeof *alloc, GFP_KERNEL);
		INIT_LIST_HEAD(&intmem_allocations);
		intmem_virtual = ioremap(MEM_INTMEM_START, MEM_INTMEM_SIZE);
		initiated = 1;
		alloc->size = MEM_INTMEM_SIZE;
		alloc->offset = 0;
		alloc->status = STATUS_FREE;
		list_add_tail(&alloc->entry, &intmem_allocations);
	}
}

void* crisv32_intmem_alloc(unsigned size, unsigned align)
{
	struct intmem_allocation* allocation;
	struct intmem_allocation* tmp;
	void* ret = NULL;

	preempt_disable();
	crisv32_intmem_init();

	list_for_each_entry_safe(allocation, tmp, &intmem_allocations, entry) {
		int alignment = allocation->offset % align;
		alignment = alignment ? align - alignment : alignment;

		if (allocation->status == STATUS_FREE &&
		    allocation->size >= size + alignment) {
			if (allocation->size > size + alignment) {
				struct intmem_allocation* alloc =
					(struct intmem_allocation*)
					kmalloc(sizeof *alloc, GFP_ATOMIC);
				alloc->status = STATUS_FREE;
				alloc->size = allocation->size - size - alignment;
				alloc->offset = allocation->offset + size;
				list_add(&alloc->entry, &allocation->entry);

				if (alignment) {
					struct intmem_allocation* tmp;
					tmp = (struct intmem_allocation*)
						kmalloc(sizeof *tmp, GFP_ATOMIC);
					tmp->offset = allocation->offset;
					tmp->size = alignment;
					tmp->status = STATUS_FREE;
					allocation->offset += alignment;
					list_add_tail(&tmp->entry, &allocation->entry);
				}
			}
			allocation->status = STATUS_ALLOCATED;
			allocation->size = size;
			ret = (void*)((int)intmem_virtual + allocation->offset);
		}
	}
	preempt_enable();
	return ret;
}

void crisv32_intmem_free(void* addr)
{
	struct intmem_allocation* allocation;
	struct intmem_allocation* tmp;

	if (addr == NULL)
		return;

	preempt_disable();
	crisv32_intmem_init();

	list_for_each_entry_safe(allocation, tmp, &intmem_allocations, entry) {
		if (allocation->offset == (int)(addr - intmem_virtual)) {
			struct intmem_allocation* prev =
			  list_entry(allocation->entry.prev,
			             struct intmem_allocation, entry);
			struct intmem_allocation* next =
			  list_entry(allocation->entry.next,
				     struct intmem_allocation, entry);

			allocation->status = STATUS_FREE;
			/* Join with prev and/or next if also free */
			if (prev->status == STATUS_FREE) {
				prev->size += allocation->size;
				list_del(&allocation->entry);
				kfree(allocation);
				allocation = prev;
			}
			if (next->status == STATUS_FREE) {
				allocation->size += next->size;
				list_del(&next->entry);
				kfree(next);
			}
			preempt_enable();
			return;
		}
	}
	preempt_enable();
}

void* crisv32_intmem_phys_to_virt(unsigned long addr)
{
	return (void*)(addr - MEM_INTMEM_START+
	               (unsigned long)intmem_virtual);
}

unsigned long crisv32_intmem_virt_to_phys(void* addr)
{
	return (unsigned long)((unsigned long )addr -
	  (unsigned long)intmem_virtual + MEM_INTMEM_START);
}