arch/arm/plat-omap/sram.c

   1 /*
   2  * linux/arch/arm/plat-omap/sram.c
   3  *
   4  * OMAP SRAM detection and management
   5  *
   6  * Copyright (C) 2005 Nokia Corporation
   7  * Written by Tony Lindgren <tony@atomide.com>
   8  *
   9  * Copyright (C) 2009-2012 Texas Instruments
  10  * Added OMAP4/5 support - Santosh Shilimkar <santosh.shilimkar@ti.com>
  11  *
  12  * This program is free software; you can redistribute it and/or modify
  13  * it under the terms of the GNU General Public License version 2 as
  14  * published by the Free Software Foundation.
  15  */
  16 #undef DEBUG
  17
  18 #include <linux/module.h>
  19 #include <linux/kernel.h>
  20 #include <linux/init.h>
  21 #include <linux/io.h>
  22
  23 #include <asm/fncpy.h>
  24 #include <asm/tlb.h>
  25 #include <asm/cacheflush.h>
  26
  27 #include <asm/mach/map.h>
  28
  29 #include <plat/sram.h>
  30
  31 #define ROUND_DOWN(value,boundary)      ((value) & (~((boundary)-1)))
  32
  33 static void __iomem *omap_sram_base;
  34 static unsigned long omap_sram_skip;
  35 static unsigned long omap_sram_size;
  36 static void __iomem *omap_sram_ceil;
  37
  38 /*
  39  * Memory allocator for SRAM: calculates the new ceiling address
  40  * for pushing a function using the fncpy API.
  41  *
  42  * Note that fncpy requires the returned address to be aligned
  43  * to an 8-byte boundary.
  44  */
  45 void *omap_sram_push_address(unsigned long size)
  46 {
  47         unsigned long available, new_ceil = (unsigned long)omap_sram_ceil;
  48
  49         available = omap_sram_ceil - (omap_sram_base + omap_sram_skip);
  50
  51         if (size > available) {
  52                 pr_err("Not enough space in SRAM\n");
  53                 return NULL;
  54         }
  55
  56         new_ceil -= size;
  57         new_ceil = ROUND_DOWN(new_ceil, FNCPY_ALIGN);
  58         omap_sram_ceil = IOMEM(new_ceil);
  59
  60         return (void *)omap_sram_ceil;
  61 }
  62
  63 /*
  64  * The SRAM context is lost during off-idle and stack
  65  * needs to be reset.
  66  */
  67 void omap_sram_reset(void)
  68 {
  69         omap_sram_ceil = omap_sram_base + omap_sram_size;
  70 }
  71
  72 /*
  73  * Note that we cannot use ioremap for SRAM, as clock init needs SRAM early.
  74  */
  75 void __init omap_map_sram(unsigned long start, unsigned long size,
  76                                  unsigned long skip, int cached)
  77 {
  78         if (size == 0)
  79                 return;
  80
  81         start = ROUND_DOWN(start, PAGE_SIZE);
  82         omap_sram_size = size;
  83         omap_sram_skip = skip;
  84         omap_sram_base = __arm_ioremap_exec(start, size, cached);
  85         if (!omap_sram_base) {
  86                 pr_err("SRAM: Could not map\n");
  87                 return;
  88         }
  89
  90         omap_sram_reset();
  91
  92         /*
  93          * Looks like we need to preserve some bootloader code at the
  94          * beginning of SRAM for jumping to flash for reboot to work...
  95          */
  96         memset_io(omap_sram_base + omap_sram_skip, 0,
  97                   omap_sram_size - omap_sram_skip);
  98 }