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/io.h>
  14 #include <linux/genalloc.h>
  15
  16 #include <mach/common.h>
  17 #include <mach/sram.h>
  18
  19 static struct gen_pool *sram_pool;
  20
  21 struct gen_pool *sram_get_gen_pool(void)
  22 {
  23         return sram_pool;
  24 }
  25
  26 void *sram_alloc(size_t len, dma_addr_t *dma)
  27 {
  28         unsigned long vaddr;
  29         dma_addr_t dma_base = davinci_soc_info.sram_dma;
  30
  31         if (dma)
  32                 *dma = 0;
  33         if (!sram_pool || (dma && !dma_base))
  34                 return NULL;
  35
  36         vaddr = gen_pool_alloc(sram_pool, len);
  37         if (!vaddr)
  38                 return NULL;
  39
  40         if (dma)
  41                 *dma = gen_pool_virt_to_phys(sram_pool, vaddr);
  42         return (void *)vaddr;
  43
  44 }
  45 EXPORT_SYMBOL(sram_alloc);
  46
  47 void sram_free(void *addr, size_t len)
  48 {
  49         gen_pool_free(sram_pool, (unsigned long) addr, len);
  50 }
  51 EXPORT_SYMBOL(sram_free);
  52
  53
  54 /*
  55  * REVISIT This supports CPU and DMA access to/from SRAM, but it
  56  * doesn't (yet?) support some other notable uses of SRAM:  as TCM
  57  * for data and/or instructions; and holding code needed to enter
  58  * and exit suspend states (while DRAM can't be used).
  59  */
  60 static int __init sram_init(void)
  61 {
  62         phys_addr_t phys = davinci_soc_info.sram_dma;
  63         unsigned len = davinci_soc_info.sram_len;
  64         int status = 0;
  65         void __iomem *addr;
  66
  67         if (len) {
  68                 len = min_t(unsigned, len, SRAM_SIZE);
  69                 sram_pool = gen_pool_create(ilog2(SRAM_GRANULARITY), -1);
  70                 if (!sram_pool)
  71                         status = -ENOMEM;
  72         }
  73
  74         if (sram_pool) {
  75                 addr = ioremap(phys, len);
  76                 if (!addr)
  77                         return -ENOMEM;
  78                 status = gen_pool_add_virt(sram_pool, (unsigned long) addr,
  79                                            phys, len, -1);
  80                 if (status < 0)
  81                         iounmap(addr);
  82         }
  83
  84         WARN_ON(status < 0);
  85         return status;
  86 }
  87 core_initcall(sram_init);
  88