sram.c
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/*
* linux/arch/arm/plat-omap/sram.c
*
* OMAP SRAM detection and management
*
* Copyright (C) 2005 Nokia Corporation
* Written by Tony Lindgren <tony@atomide.com>
*
* Copyright (C) 2009-2012 Texas Instruments
* Added OMAP4/5 support - Santosh Shilimkar <santosh.shilimkar@ti.com>
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License version 2 as
* published by the Free Software Foundation.
*/
#undef DEBUG
#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/init.h>
#include <linux/io.h>
#include <asm/fncpy.h>
#include <asm/tlb.h>
#include <asm/cacheflush.h>
#include <asm/mach/map.h>
#include <plat/sram.h>
#define ROUND_DOWN(value,boundary) ((value) & (~((boundary)-1)))
static void __iomem *omap_sram_base;
static unsigned long omap_sram_skip;
static unsigned long omap_sram_size;
static void __iomem *omap_sram_ceil;
/*
* Memory allocator for SRAM: calculates the new ceiling address
* for pushing a function using the fncpy API.
*
* Note that fncpy requires the returned address to be aligned
* to an 8-byte boundary.
*/
void *omap_sram_push_address(unsigned long size)
{
unsigned long available, new_ceil = (unsigned long)omap_sram_ceil;
available = omap_sram_ceil - (omap_sram_base + omap_sram_skip);
if (size > available) {
pr_err("Not enough space in SRAM\n");
return NULL;
}
new_ceil -= size;
new_ceil = ROUND_DOWN(new_ceil, FNCPY_ALIGN);
omap_sram_ceil = IOMEM(new_ceil);
return (void *)omap_sram_ceil;
}
/*
* The SRAM context is lost during off-idle and stack
* needs to be reset.
*/
void omap_sram_reset(void)
{
omap_sram_ceil = omap_sram_base + omap_sram_size;
}
/*
* Note that we cannot use ioremap for SRAM, as clock init needs SRAM early.
*/
void __init omap_map_sram(unsigned long start, unsigned long size,
unsigned long skip, int cached)
{
if (size == 0)
return;
start = ROUND_DOWN(start, PAGE_SIZE);
omap_sram_size = size;
omap_sram_skip = skip;
omap_sram_base = __arm_ioremap_exec(start, size, cached);
if (!omap_sram_base) {
pr_err("SRAM: Could not map\n");
return;
}
omap_sram_reset();
/*
* Looks like we need to preserve some bootloader code at the
* beginning of SRAM for jumping to flash for reboot to work...
*/
memset_io(omap_sram_base + omap_sram_skip, 0,
omap_sram_size - omap_sram_skip);
}