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/kernel.h>
  13 #include <linux/init.h>
  14 #include <linux/genalloc.h>
  15
  16 #include <mach/common.h>
  17 #include <mach/memory.h>
  18 #include <mach/sram.h>
  19
  20
  21 static struct gen_pool *sram_pool;
  22
  23 void *sram_alloc(size_t len, dma_addr_t *dma)
  24 {
  25         unsigned long vaddr;
  26         dma_addr_t dma_base = davinci_soc_info.sram_dma;
  27
  28         if (dma)
  29                 *dma = 0;
  30         if (!sram_pool || (dma && !dma_base))
  31                 return NULL;
  32
  33         vaddr = gen_pool_alloc(sram_pool, len);
  34         if (!vaddr)
  35                 return NULL;
  36
  37         if (dma)
  38                 *dma = dma_base + (vaddr - SRAM_VIRT);
  39         return (void *)vaddr;
  40
  41 }
  42 EXPORT_SYMBOL(sram_alloc);
  43
  44 void sram_free(void *addr, size_t len)
  45 {
  46         gen_pool_free(sram_pool, (unsigned long) addr, len);
  47 }
  48 EXPORT_SYMBOL(sram_free);
  49
  50
  51 /*
  52  * REVISIT This supports CPU and DMA access to/from SRAM, but it
  53  * doesn't (yet?) support some other notable uses of SRAM:  as TCM
  54  * for data and/or instructions; and holding code needed to enter
  55  * and exit suspend states (while DRAM can't be used).
  56  */
  57 static int __init sram_init(void)
  58 {
  59         unsigned len = davinci_soc_info.sram_len;
  60         int status = 0;
  61
  62         if (len) {
  63                 len = min_t(unsigned, len, SRAM_SIZE);
  64                 sram_pool = gen_pool_create(ilog2(SRAM_GRANULARITY), -1);
  65                 if (!sram_pool)
  66                         status = -ENOMEM;
  67         }
  68         if (sram_pool)
  69                 status = gen_pool_add(sram_pool, SRAM_VIRT, len, -1);
  70         WARN_ON(status < 0);
  71         return status;
  72 }
  73 core_initcall(sram_init);
  74