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/*
* Copyright (C) 2010 ARM Limited. All rights reserved.
*
* This program is free software and is provided to you under the terms of the GNU General Public License version 2
* as published by the Free Software Foundation, and any use by you of this program is subject to the terms of such GNU licence.
*
* A copy of the licence is included with the program, and can also be obtained from Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
*/

/* needed to detect kernel version specific code */
#include <linux/version.h>

#if LINUX_VERSION_CODE >= KERNEL_VERSION(2,6,26)
#include <linux/semaphore.h>
#else /* pre 2.6.26 the file was in the arch specific location */
#include <asm/semaphore.h>
#endif

#include <linux/mm.h>
#include <linux/slab.h>
#include <asm/atomic.h>
#include <linux/vmalloc.h>
#include "ump_kernel_common.h"
#include "ump_kernel_memory_backend.h"



#define UMP_BLOCK_SIZE (256UL * 1024UL) /* 256kB, remember to keep the ()s */



typedef struct block_info
{
struct block_info * next;
} block_info;



typedef struct block_allocator
{
struct semaphore mutex;
block_info * all_blocks;
block_info * first_free;
u32 base;
u32 num_blocks;
u32 num_free;
} block_allocator;


static void block_allocator_shutdown(ump_memory_backend * backend);
static int block_allocator_allocate(void* ctx, ump_dd_mem * mem);
static void block_allocator_release(void * ctx, ump_dd_mem * handle);
static inline u32 get_phys(block_allocator * allocator, block_info * block);



/*
* Create dedicated memory backend
*/
ump_memory_backend * ump_block_allocator_create(u32 base_address, u32 size)
{
ump_memory_backend * backend;
block_allocator * allocator;
u32 usable_size;
u32 num_blocks;

usable_size = (size + UMP_BLOCK_SIZE - 1) & ~(UMP_BLOCK_SIZE - 1);
num_blocks = usable_size / UMP_BLOCK_SIZE;

if (0 == usable_size)
{
DBG_MSG(1, ("Memory block of size %u is unusable\n", size));
return NULL;
}

DBG_MSG(5, ("Creating dedicated UMP memory backend. Base address: 0x%08x, size: 0x%08x\n", base_address, size));
DBG_MSG(6, ("%u usable bytes which becomes %u blocks\n", usable_size, num_blocks));

backend = kzalloc(sizeof(ump_memory_backend), GFP_KERNEL);
if (NULL != backend)
{
allocator = kmalloc(sizeof(block_allocator), GFP_KERNEL);
if (NULL != allocator)
{
allocator->all_blocks = kmalloc(sizeof(block_allocator) * num_blocks, GFP_KERNEL);
if (NULL != allocator->all_blocks)
{
int i;

allocator->first_free = NULL;
allocator->num_blocks = num_blocks;
allocator->num_free = num_blocks;
allocator->base = base_address;
sema_init(&allocator->mutex, 1);

for (i = 0; i < num_blocks; i++)
{
allocator->all_blocks[i].next = allocator->first_free;
allocator->first_free = &allocator->all_blocks[i];
}

backend->ctx = allocator;
backend->allocate = block_allocator_allocate;
backend->release = block_allocator_release;
backend->shutdown = block_allocator_shutdown;
backend->pre_allocate_physical_check = NULL;
backend->adjust_to_mali_phys = NULL;
backend->get = NULL;
backend->set = NULL;

return backend;
}
kfree(allocator);
}
kfree(backend);
}

return NULL;
}



/*
* Destroy specified dedicated memory backend
*/
static void block_allocator_shutdown(ump_memory_backend * backend)
{
block_allocator * allocator;

BUG_ON(!backend);
BUG_ON(!backend->ctx);

allocator = (block_allocator*)backend->ctx;

DBG_MSG_IF(1, allocator->num_free != allocator->num_blocks, ("%u blocks still in use during shutdown\n", allocator->num_blocks - allocator->num_free));

kfree(allocator->all_blocks);
kfree(allocator);
kfree(backend);
}



static int block_allocator_allocate(void* ctx, ump_dd_mem * mem)
{
block_allocator * allocator;
u32 left;
block_info * last_allocated = NULL;
int i = 0;

BUG_ON(!ctx);
BUG_ON(!mem);

allocator = (block_allocator*)ctx;
left = mem->size_bytes;

BUG_ON(!left);
BUG_ON(!&allocator->mutex);

mem->nr_blocks = ((left + UMP_BLOCK_SIZE - 1) & ~(UMP_BLOCK_SIZE - 1)) / UMP_BLOCK_SIZE;
mem->block_array = (ump_dd_physical_block*)vmalloc(sizeof(ump_dd_physical_block) * mem->nr_blocks);
if (NULL == mem->block_array)
{
MSG_ERR(("Failed to allocate block array\n"));
return 0;
}

if (down_interruptible(&allocator->mutex))
{
MSG_ERR(("Could not get mutex to do block_allocate\n"));
return 0;
}

mem->size_bytes = 0;

while ((left > 0) && (allocator->first_free))
{
block_info * block;

block = allocator->first_free;
allocator->first_free = allocator->first_free->next;
block->next = last_allocated;
last_allocated = block;
allocator->num_free--;

mem->block_array[i].addr = get_phys(allocator, block);
mem->block_array[i].size = UMP_BLOCK_SIZE;
mem->size_bytes += UMP_BLOCK_SIZE;

i++;

if (left < UMP_BLOCK_SIZE) left = 0;
else left -= UMP_BLOCK_SIZE;
}

if (left)
{
block_info * block;
/* release all memory back to the pool */
while (last_allocated)
{
block = last_allocated->next;
last_allocated->next = allocator->first_free;
allocator->first_free = last_allocated;
last_allocated = block;
allocator->num_free++;
}

vfree(mem->block_array);
mem->backend_info = NULL;
mem->block_array = NULL;

DBG_MSG(4, ("Could not find a mem-block for the allocation.\n"));
up(&allocator->mutex);

return 0;
}

mem->backend_info = last_allocated;

up(&allocator->mutex);

return 1;
}



static void block_allocator_release(void * ctx, ump_dd_mem * handle)
{
block_allocator * allocator;
block_info * block, * next;

BUG_ON(!ctx);
BUG_ON(!handle);

allocator = (block_allocator*)ctx;
block = (block_info*)handle->backend_info;
BUG_ON(!block);

if (down_interruptible(&allocator->mutex))
{
MSG_ERR(("Allocator release: Failed to get mutex - memory leak\n"));
return;
}

while (block)
{
next = block->next;

BUG_ON( (block < allocator->all_blocks) || (block > (allocator->all_blocks + allocator->num_blocks)));

block->next = allocator->first_free;
allocator->first_free = block;
allocator->num_free++;

block = next;
}
DBG_MSG(3, ("%d blocks free after release call\n", allocator->num_free));
up(&allocator->mutex);

vfree(handle->block_array);
handle->block_array = NULL;
}



/*
* Helper function for calculating the physical base adderss of a memory block
*/
static inline u32 get_phys(block_allocator * allocator, block_info * block)
{
return allocator->base + ((block - allocator->all_blocks) * UMP_BLOCK_SIZE);
}
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