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 #include <asm/set_memory.h>
  27
  28 #include <asm/mach/map.h>
  29
  30 #include <plat/sram.h>
  31
  32 #define ROUND_DOWN(value,boundary)      ((value) & (~((boundary)-1)))
  33
  34 static void __iomem *omap_sram_base;
  35 static unsigned long omap_sram_skip;
  36 static unsigned long omap_sram_size;
  37 static void __iomem *omap_sram_ceil;
  38
  39 /*
  40  * Memory allocator for SRAM: calculates the new ceiling address
  41  * for pushing a function using the fncpy API.
  42  *
  43  * Note that fncpy requires the returned address to be aligned
  44  * to an 8-byte boundary.
  45  */
  46 static void *omap_sram_push_address(unsigned long size)
  47 {
  48         unsigned long available, new_ceil = (unsigned long)omap_sram_ceil;
  49
  50         available = omap_sram_ceil - (omap_sram_base + omap_sram_skip);
  51
  52         if (size > available) {
  53                 pr_err("Not enough space in SRAM\n");
  54                 return NULL;
  55         }
  56
  57         new_ceil -= size;
  58         new_ceil = ROUND_DOWN(new_ceil, FNCPY_ALIGN);
  59         omap_sram_ceil = IOMEM(new_ceil);
  60
  61         return (void *)omap_sram_ceil;
  62 }
  63
  64 void *omap_sram_push(void *funcp, unsigned long size)
  65 {
  66         void *sram;
  67         unsigned long base;
  68         int pages;
  69         void *dst = NULL;
  70
  71         sram = omap_sram_push_address(size);
  72         if (!sram)
  73                 return NULL;
  74
  75         base = (unsigned long)sram & PAGE_MASK;
  76         pages = PAGE_ALIGN(size) / PAGE_SIZE;
  77
  78         set_memory_rw(base, pages);
  79
  80         dst = fncpy(sram, funcp, size);
  81
  82         set_memory_ro(base, pages);
  83         set_memory_x(base, pages);
  84
  85         return dst;
  86 }
  87
  88 /*
  89  * The SRAM context is lost during off-idle and stack
  90  * needs to be reset.
  91  */
  92 void omap_sram_reset(void)
  93 {
  94         omap_sram_ceil = omap_sram_base + omap_sram_size;
  95 }
  96
  97 /*
  98  * Note that we cannot use ioremap for SRAM, as clock init needs SRAM early.
  99  */
 100 void __init omap_map_sram(unsigned long start, unsigned long size,
 101                                  unsigned long skip, int cached)
 102 {
 103         unsigned long base;
 104         int pages;
 105
 106         if (size == 0)
 107                 return;
 108
 109         start = ROUND_DOWN(start, PAGE_SIZE);
 110         omap_sram_size = size;
 111         omap_sram_skip = skip;
 112         omap_sram_base = __arm_ioremap_exec(start, size, cached);
 113         if (!omap_sram_base) {
 114                 pr_err("SRAM: Could not map\n");
 115                 return;
 116         }
 117
 118         omap_sram_reset();
 119
 120         /*
 121          * Looks like we need to preserve some bootloader code at the
 122          * beginning of SRAM for jumping to flash for reboot to work...
 123          */
 124         memset_io(omap_sram_base + omap_sram_skip, 0,
 125                   omap_sram_size - omap_sram_skip);
 126
 127         base = (unsigned long)omap_sram_base;
 128         pages = PAGE_ALIGN(omap_sram_size) / PAGE_SIZE;
 129
 130         set_memory_ro(base, pages);
 131         set_memory_x(base, pages);
 132 }