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sram.c

/*
 * mach-davinci/sram.c - DaVinci simple SRAM allocator
 *
 * Copyright (C) 2009 David Brownell
 *
 * 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.
 */
#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/init.h>
#include <linux/genalloc.h>

#include <mach/common.h>
#include <mach/memory.h>
#include <mach/sram.h>


static struct gen_pool *sram_pool;

void *sram_alloc(size_t len, dma_addr_t *dma)
{
      unsigned long vaddr;
      dma_addr_t dma_base = davinci_soc_info.sram_dma;

      if (dma)
            *dma = 0;
      if (!sram_pool || (dma && !dma_base))
            return NULL;

      vaddr = gen_pool_alloc(sram_pool, len);
      if (!vaddr)
            return NULL;

      if (dma)
            *dma = dma_base + (vaddr - SRAM_VIRT);
      return (void *)vaddr;

}
EXPORT_SYMBOL(sram_alloc);

void sram_free(void *addr, size_t len)
{
      gen_pool_free(sram_pool, (unsigned long) addr, len);
}
EXPORT_SYMBOL(sram_free);


/*
 * REVISIT This supports CPU and DMA access to/from SRAM, but it
 * doesn't (yet?) support some other notable uses of SRAM:  as TCM
 * for data and/or instructions; and holding code needed to enter
 * and exit suspend states (while DRAM can't be used).
 */
static int __init sram_init(void)
{
      unsigned len = davinci_soc_info.sram_len;
      int status = 0;

      if (len) {
            len = min(len, SRAM_SIZE);
            sram_pool = gen_pool_create(ilog2(SRAM_GRANULARITY), -1);
            if (!sram_pool)
                  status = -ENOMEM;
      }
      if (sram_pool)
            status = gen_pool_add(sram_pool, SRAM_VIRT, len, -1);
      WARN_ON(status < 0);
      return status;
}
core_initcall(sram_init);


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