text: // SPDX-License-Identifier: GPL-2.0-only
  /*
   * 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>
   */
  #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/set_memory.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.
   */
  static 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;
  }
  
  void *omap_sram_push(void *funcp, unsigned long size)
  {
  	void *sram;
  	unsigned long base;
  	int pages;
  	void *dst = NULL;
  
  	sram = omap_sram_push_address(size);
  	if (!sram)
  		return NULL;
  
  	base = (unsigned long)sram & PAGE_MASK;
  	pages = PAGE_ALIGN(size) / PAGE_SIZE;
  
  	set_memory_rw(base, pages);
  
  	dst = fncpy(sram, funcp, size);
  
  	set_memory_ro(base, pages);
  	set_memory_x(base, pages);
  
  	return dst;
  }
  
  /*
   * 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)
  {
  	unsigned long base;
  	int pages;
  
  	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);
  
  	base = (unsigned long)omap_sram_base;
  	pages = PAGE_ALIGN(omap_sram_size) / PAGE_SIZE;
  
  	set_memory_ro(base, pages);
  	set_memory_x(base, pages);
  }
  