arch/arm/plat-omap/sram.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * linux/arch/arm/plat-omap/sram.c
   4  *
   5  * OMAP SRAM detection and management
   6  *
   7  * Copyright (C) 2005 Nokia Corporation
   8  * Written by Tony Lindgren <tony@atomide.com>
   9  *
  10  * Copyright (C) 2009-2012 Texas Instruments
  11  * Added OMAP4/5 support - Santosh Shilimkar <santosh.shilimkar@ti.com>
  12  */
  13 #undef DEBUG
  14
  15 #include <linux/module.h>
  16 #include <linux/kernel.h>
  17 #include <linux/init.h>
  18 #include <linux/io.h>
  19
  20 #include <asm/fncpy.h>
  21 #include <asm/tlb.h>
  22 #include <asm/cacheflush.h>
  23 #include <asm/set_memory.h>
  24
  25 #include <asm/mach/map.h>
  26
  27 #include <plat/sram.h>
  28
  29 #define ROUND_DOWN(value,boundary)      ((value) & (~((boundary)-1)))
  30
  31 static void __iomem *omap_sram_base;
  32 static unsigned long omap_sram_skip;
  33 static unsigned long omap_sram_size;
  34 static void __iomem *omap_sram_ceil;
  35
  36 /*
  37  * Memory allocator for SRAM: calculates the new ceiling address
  38  * for pushing a function using the fncpy API.
  39  *
  40  * Note that fncpy requires the returned address to be aligned
  41  * to an 8-byte boundary.
  42  */
  43 static void *omap_sram_push_address(unsigned long size)
  44 {
  45         unsigned long available, new_ceil = (unsigned long)omap_sram_ceil;
  46
  47         available = omap_sram_ceil - (omap_sram_base + omap_sram_skip);
  48
  49         if (size > available) {
  50                 pr_err("Not enough space in SRAM\n");
  51                 return NULL;
  52         }
  53
  54         new_ceil -= size;
  55         new_ceil = ROUND_DOWN(new_ceil, FNCPY_ALIGN);
  56         omap_sram_ceil = IOMEM(new_ceil);
  57
  58         return (void *)omap_sram_ceil;
  59 }
  60
  61 void *omap_sram_push(void *funcp, unsigned long size)
  62 {
  63         void *sram;
  64         unsigned long base;
  65         int pages;
  66         void *dst = NULL;
  67
  68         sram = omap_sram_push_address(size);
  69         if (!sram)
  70                 return NULL;
  71
  72         base = (unsigned long)sram & PAGE_MASK;
  73         pages = PAGE_ALIGN(size) / PAGE_SIZE;
  74
  75         set_memory_rw(base, pages);
  76
  77         dst = fncpy(sram, funcp, size);
  78
  79         set_memory_ro(base, pages);
  80         set_memory_x(base, pages);
  81
  82         return dst;
  83 }
  84
  85 /*
  86  * The SRAM context is lost during off-idle and stack
  87  * needs to be reset.
  88  */
  89 void omap_sram_reset(void)
  90 {
  91         omap_sram_ceil = omap_sram_base + omap_sram_size;
  92 }
  93
  94 /*
  95  * Note that we cannot use ioremap for SRAM, as clock init needs SRAM early.
  96  */
  97 void __init omap_map_sram(unsigned long start, unsigned long size,
  98                                  unsigned long skip, int cached)
  99 {
 100         unsigned long base;
 101         int pages;
 102
 103         if (size == 0)
 104                 return;
 105
 106         start = ROUND_DOWN(start, PAGE_SIZE);
 107         omap_sram_size = size;
 108         omap_sram_skip = skip;
 109         omap_sram_base = __arm_ioremap_exec(start, size, cached);
 110         if (!omap_sram_base) {
 111                 pr_err("SRAM: Could not map\n");
 112                 return;
 113         }
 114
 115         omap_sram_reset();
 116
 117         /*
 118          * Looks like we need to preserve some bootloader code at the
 119          * beginning of SRAM for jumping to flash for reboot to work...
 120          */
 121         memset_io(omap_sram_base + omap_sram_skip, 0,
 122                   omap_sram_size - omap_sram_skip);
 123
 124         base = (unsigned long)omap_sram_base;
 125         pages = PAGE_ALIGN(omap_sram_size) / PAGE_SIZE;
 126
 127         set_memory_ro(base, pages);
 128         set_memory_x(base, pages);
 129 }