release/src-rt-6.x.4708/linux/linux-2.6.36/arch/arm/mach-davinci/sram.c

   1 /*
   2  * mach-davinci/sram.c - DaVinci simple SRAM allocator
   3  *
   4  * Copyright (C) 2009 David Brownell
   5  *
   6  * This program is free software; you can redistribute it and/or modify
   7  * it under the terms of the GNU General Public License as published by
   8  * the Free Software Foundation; either version 2 of the License, or
   9  * (at your option) any later version.
  10  */
  11 #include <linux/module.h>
  12 #include <linux/init.h>
  13 #include <linux/genalloc.h>
  14
  15 #include <mach/common.h>
  16 #include <mach/sram.h>
  17
  18 static struct gen_pool *sram_pool;
  19
  20 void *sram_alloc(size_t len, dma_addr_t *dma)
  21 {
  22         unsigned long vaddr;
  23         dma_addr_t dma_base = davinci_soc_info.sram_dma;
  24
  25         if (dma)
  26                 *dma = 0;
  27         if (!sram_pool || (dma && !dma_base))
  28                 return NULL;
  29
  30         vaddr = gen_pool_alloc(sram_pool, len);
  31         if (!vaddr)
  32                 return NULL;
  33
  34         if (dma)
  35                 *dma = dma_base + (vaddr - SRAM_VIRT);
  36         return (void *)vaddr;
  37
  38 }
  39 EXPORT_SYMBOL(sram_alloc);
  40
  41 void sram_free(void *addr, size_t len)
  42 {
  43         gen_pool_free(sram_pool, (unsigned long) addr, len);
  44 }
  45 EXPORT_SYMBOL(sram_free);
  46
  47
  48 /*
  49  * REVISIT This supports CPU and DMA access to/from SRAM, but it
  50  * doesn't (yet?) support some other notable uses of SRAM:  as TCM
  51  * for data and/or instructions; and holding code needed to enter
  52  * and exit suspend states (while DRAM can't be used).
  53  */
  54 static int __init sram_init(void)
  55 {
  56         unsigned len = davinci_soc_info.sram_len;
  57         int status = 0;
  58
  59         if (len) {
  60                 len = min_t(unsigned, len, SRAM_SIZE);
  61                 sram_pool = gen_pool_create(ilog2(SRAM_GRANULARITY), -1);
  62                 if (!sram_pool)
  63                         status = -ENOMEM;
  64         }
  65         if (sram_pool)
  66                 status = gen_pool_add(sram_pool, SRAM_VIRT, len, -1);
  67         WARN_ON(status < 0);
  68         return status;
  69 }
  70 core_initcall(sram_init);