/******************************************************************************
* Copyright (c) 2011 Xilinx, Inc.  All rights reserved. 
* 
* Xilinx, Inc. 
* XILINX IS PROVIDING THIS DESIGN, CODE, OR INFORMATION "AS IS" AS A 
* COURTESY TO YOU.  BY PROVIDING THIS DESIGN, CODE, OR INFORMATION AS 
* ONE POSSIBLE   IMPLEMENTATION OF THIS FEATURE, APPLICATION OR 
* STANDARD, XILINX IS MAKING NO REPRESENTATION THAT THIS IMPLEMENTATION 
* IS FREE FROM ANY CLAIMS OF INFRINGEMENT, AND YOU ARE RESPONSIBLE 
* FOR OBTAINING ANY RIGHTS YOU MAY REQUIRE FOR YOUR IMPLEMENTATION. 
* XILINX EXPRESSLY DISCLAIMS ANY WARRANTY WHATSOEVER WITH RESPECT TO 
* THE ADEQUACY OF THE IMPLEMENTATION, INCLUDING BUT NOT LIMITED TO 
* ANY WARRANTIES OR REPRESENTATIONS THAT THIS IMPLEMENTATION IS FREE 
* FROM CLAIMS OF INFRINGEMENT, IMPLIED WARRANTIES OF MERCHANTABILITY 
* AND FITNESS FOR A PARTICULAR PURPOSE. 
*
* microblaze_scrub ()
*
*    Scrub LMB memory and all internal BRAMs (data cache, instruction cache,
*    MMU UTLB and branch target cache) in MicroBlaze to reduce the possibility
*    of an uncorrectable error when fault tolerance support is enabled.
*
*    This routine assumes that the processor is in privileged mode when it is
*    called, if the MMU is enabled.
*
*    Call this routine regularly from a timer interrupt.
*
*    Parameters:
*       None
*
* $Id: microblaze_scrub.S,v 1.1.2.1 2011/05/17 04:37:32 sadanan Exp $
*
*******************************************************************************/

#include "xparameters.h"

/* Define if fault tolerance is used */
#ifdef XPAR_MICROBLAZE_FAULT_TOLERANT
  #if XPAR_MICROBLAZE_FAULT_TOLERANT > 0
    #define FAULT_TOLERANT
  #endif
#endif

/* Define if LMB is used and can be scrubbed */
#if defined(XPAR_MICROBLAZE_D_LMB) &&            \
	    defined(XPAR_DLMB_CNTLR_BASEADDR) && \
	    defined(XPAR_DLMB_CNTLR_HIGHADDR)
  #if XPAR_MICROBLAZE_D_LMB == 1
    #define HAS_SCRUBBABLE_LMB
    #define DLMB_MASK (XPAR_DLMB_CNTLR_HIGHADDR - XPAR_DLMB_CNTLR_BASEADDR)
  #endif
#endif

/* Set default cache line lengths */
#ifndef XPAR_MICROBLAZE_DCACHE_LINE_LEN
  #define XPAR_MICROBLAZE_DCACHE_LINE_LEN   4
#endif

#ifndef XPAR_MICROBLAZE_ICACHE_LINE_LEN
  #define XPAR_MICROBLAZE_ICACHE_LINE_LEN   4
#endif

/* Define if internal Data Cache BRAMs are used */
#if defined(XPAR_MICROBLAZE_USE_DCACHE) && defined(XPAR_MICROBLAZE_DCACHE_BYTE_SIZE)
  #if XPAR_MICROBLAZE_USE_DCACHE == 1 && XPAR_MICROBLAZE_DCACHE_BYTE_SIZE > 1024
    #define HAS_BRAM_DCACHE
    #define DCACHE_INCREMENT (XPAR_MICROBLAZE_DCACHE_LINE_LEN * 4)
    #define DCACHE_MASK (XPAR_MICROBLAZE_DCACHE_BYTE_SIZE - 1)
  #endif
#endif

/* Define if internal Instruction Cache BRAMs are used */
#if defined(XPAR_MICROBLAZE_USE_ICACHE) && defined(XPAR_MICROBLAZE_CACHE_BYTE_SIZE)
  #if XPAR_MICROBLAZE_USE_ICACHE == 1 && XPAR_MICROBLAZE_CACHE_BYTE_SIZE > 1024
    #define HAS_BRAM_ICACHE
    #define ICACHE_INCREMENT (XPAR_MICROBLAZE_ICACHE_LINE_LEN * 4)
    #define ICACHE_MASK (XPAR_MICROBLAZE_CACHE_BYTE_SIZE - 1)
  #endif
#endif

/* Define if internal MMU UTLB BRAM is used */
#ifdef XPAR_MICROBLAZE_USE_MMU
  #if XPAR_MICROBLAZE_USE_MMU > 1
    #define HAS_BRAM_MMU_UTLB
  #endif
#endif

/* Define if internal BTC BRAM is used, and match BTC clear to a complete cache scrub */
#if defined(XPAR_MICROBLAZE_USE_BRANCH_TARGET_CACHE) && \
    defined(XPAR_MICROBLAZE_BRANCH_TARGET_CACHE_SIZE)
  #if XPAR_MICROBLAZE_USE_BRANCH_TARGET_CACHE == 1
    #if XPAR_MICROBLAZE_BRANCH_TARGET_CACHE_SIZE == 0 || \
	XPAR_MICROBLAZE_BRANCH_TARGET_CACHE_SIZE >  4
      #define HAS_BRAM_BRANCH_TARGET_CACHE
      #ifdef HAS_BRAM_DCACHE
	#define BTC_MASK_D (XPAR_MICROBLAZE_DCACHE_BYTE_SIZE/DCACHE_INCREMENT-1)
      #else
	#define BTC_MASK_D 256
      #endif
      #ifdef HAS_BRAM_ICACHE
	#define BTC_MASK_I (XPAR_MICROBLAZE_CACHE_BYTE_SIZE/ICACHE_INCREMENT-1)
      #else
	#define BTC_MASK_I 256
      #endif
      #if BTC_MASK_D > BTC_MASK_I
	#define BTC_MASK BTC_MASK_D
      #else
	#define BTC_MASK BTC_MASK_I
      #endif
    #endif
  #endif
#endif

/* Define index offsets to persistent data used by this routine */
#define DLMB_INDEX_OFFSET     0
#define DCACHE_INDEX_OFFSET   4
#define ICACHE_INDEX_OFFSET   8
#define MMU_INDEX_OFFSET      12
#define BTC_CALL_COUNT_OFFSET 16

	.text
	.globl	microblaze_scrub
	.ent	microblaze_scrub
	.align	2

microblaze_scrub:
#ifdef FAULT_TOLERANT
	la	r6, r0, L_persistent_data		/* Get pointer to data */

#ifdef HAS_SCRUBBABLE_LMB
L_dlmb:
	lwi	r5, r6, DLMB_INDEX_OFFSET		/* Get dlmb index */
	lw	r7, r5, r0				/* Load and store */
	sw	r7, r5, r0
	addik	r5, r5, 4				/* Increment and save dlmb index */
	andi	r5, r5, DLMB_MASK
	swi	r5, r6, DLMB_INDEX_OFFSET
#endif /* HAS_SCRUBBABLE_LMB */

#ifdef HAS_BRAM_DCACHE
L_dcache:
	lwi	r5, r6, DCACHE_INDEX_OFFSET		/* Get dcache line index */
	wdc	r5, r0					/* Invalidate data cache line */
	addik	r5, r5, DCACHE_INCREMENT		/* Increment and save entry index */
	andi	r5, r5, DCACHE_MASK
	swi	r5, r6, DCACHE_INDEX_OFFSET
#endif /* HAS_BRAM_DCACHE */

#ifdef HAS_BRAM_ICACHE
L_icache:
	lwi	r5, r6, ICACHE_INDEX_OFFSET		/* Get icache line index */
	wic	r5, r0					/* Invalidate data cache line */
	addik	r5, r5, ICACHE_INCREMENT		/* Increment and save entry index */
	andi	r5, r5, ICACHE_MASK
	swi	r5, r6, ICACHE_INDEX_OFFSET
#endif /* HAS_BRAM_ICACHE */

#ifdef HAS_BRAM_MMU_UTLB
L_mmu:
	lwi	r5, r6, MMU_INDEX_OFFSET		/* Get UTLB entry index */
	mts	rtlbx, r5				/* Access next entry in UTLB */
	mts	rtlbhi, r0				/* Clear the UTLB entry */

	addik	r5, r5, 1				/* Increment and save entry index */
	andi	r5, r5, 0x3F
	swi	r5, r6, MMU_INDEX_OFFSET
#endif /* HAS_BRAM_MMU_UTLB */

#ifdef HAS_BRAM_BRANCH_TARGET_CACHE
L_btc:
	lwi	r5, r6, BTC_CALL_COUNT_OFFSET		/* Get BTC call count offset */
	addik	r5, r5, 1				/* Increment and save call count */
	andi	r5, r5, BTC_MASK
	swi	r5, r6, BTC_CALL_COUNT_OFFSET

	bnei	r5, L_skip_btc_scrub			/* Skip scrub unless count wrap */
	bri	4					/* Clear branch target cache */
L_skip_btc_scrub:
#endif /* HAS_BRAM_BRANCH_TARGET_CACHE */

#endif /* FAULT_TOLERANT */
L_done:
	rtsd	r15, 8					/* Return */
	nop
	.end	microblaze_scrub

	/* Persistent data used by this routine */
	.data
	.align	2
L_persistent_data:
	.long	0					/* dlmb index      */
	.long	0					/* dcache index    */
	.long	0					/* icache index    */
	.long	0					/* mmu entry index */
	.long	0					/* btc call count  */
