text: // SPDX-License-Identifier: GPL-2.0+
  /*
   * (C) Copyright 2010-2011 Texas Instruments, <www.ti.com>
   * Mansoor Ahamed <mansoor.ahamed@ti.com>
   *
   * BCH Error Location Module (ELM) support.
   *
   * NOTE:
   * 1. Supports only continuous mode. Dont see need for page mode in uboot
   * 2. Supports only syndrome polynomial 0. i.e. poly local variable is
   *    always set to ELM_DEFAULT_POLY. Dont see need for other polynomial
   *    sets in uboot
   */
  
  #include <common.h>
  #include <asm/io.h>
  #include <linux/errno.h>
  #include <linux/mtd/omap_elm.h>
  #include <asm/arch/hardware.h>
  
  #define DRIVER_NAME		"omap-elm"
  #define ELM_DEFAULT_POLY (0)
  
  struct elm *elm_cfg;
  
  /**
   * elm_load_syndromes - Load BCH syndromes based on bch_type selection
   * @syndrome: BCH syndrome
   * @bch_type: BCH4/BCH8/BCH16
   * @poly: Syndrome Polynomial set to use
   */
  static void elm_load_syndromes(u8 *syndrome, enum bch_level bch_type, u8 poly)
  {
  	u32 *ptr;
  	u32 val;
  
  	/* reg 0 */
  	ptr = &elm_cfg->syndrome_fragments[poly].syndrome_fragment_x[0];
  	val = syndrome[0] | (syndrome[1] << 8) | (syndrome[2] << 16) |
  				(syndrome[3] << 24);
  	writel(val, ptr);
  	/* reg 1 */
  	ptr = &elm_cfg->syndrome_fragments[poly].syndrome_fragment_x[1];
  	val = syndrome[4] | (syndrome[5] << 8) | (syndrome[6] << 16) |
  				(syndrome[7] << 24);
  	writel(val, ptr);
  
  	if (bch_type == BCH_8_BIT || bch_type == BCH_16_BIT) {
  		/* reg 2 */
  		ptr = &elm_cfg->syndrome_fragments[poly].syndrome_fragment_x[2];
  		val = syndrome[8] | (syndrome[9] << 8) | (syndrome[10] << 16) |
  				(syndrome[11] << 24);
  		writel(val, ptr);
  		/* reg 3 */
  		ptr = &elm_cfg->syndrome_fragments[poly].syndrome_fragment_x[3];
  		val = syndrome[12] | (syndrome[13] << 8) |
  			(syndrome[14] << 16) | (syndrome[15] << 24);
  		writel(val, ptr);
  	}
  
  	if (bch_type == BCH_16_BIT) {
  		/* reg 4 */
  		ptr = &elm_cfg->syndrome_fragments[poly].syndrome_fragment_x[4];
  		val = syndrome[16] | (syndrome[17] << 8) |
  			(syndrome[18] << 16) | (syndrome[19] << 24);
  		writel(val, ptr);
  
  		/* reg 5 */
  		ptr = &elm_cfg->syndrome_fragments[poly].syndrome_fragment_x[5];
  		val = syndrome[20] | (syndrome[21] << 8) |
  			(syndrome[22] << 16) | (syndrome[23] << 24);
  		writel(val, ptr);
  
  		/* reg 6 */
  		ptr = &elm_cfg->syndrome_fragments[poly].syndrome_fragment_x[6];
  		val = syndrome[24] | (syndrome[25] << 8) |
  			(syndrome[26] << 16) | (syndrome[27] << 24);
  		writel(val, ptr);
  	}
  }
  
  /**
   * elm_check_errors - Check for BCH errors and return error locations
   * @syndrome: BCH syndrome
   * @bch_type: BCH4/BCH8/BCH16
   * @error_count: Returns number of errrors in the syndrome
   * @error_locations: Returns error locations (in decimal) in this array
   *
   * Check the provided syndrome for BCH errors and return error count
   * and locations in the array passed. Returns -1 if error is not correctable,
   * else returns 0
   */
  int elm_check_error(u8 *syndrome, enum bch_level bch_type, u32 *error_count,
  		u32 *error_locations)
  {
  	u8 poly = ELM_DEFAULT_POLY;
  	s8 i;
  	u32 location_status;
  
  	elm_load_syndromes(syndrome, bch_type, poly);
  
  	/* start processing */
  	writel((readl(&elm_cfg->syndrome_fragments[poly].syndrome_fragment_x[6])
  				| ELM_SYNDROME_FRAGMENT_6_SYNDROME_VALID),
  		&elm_cfg->syndrome_fragments[poly].syndrome_fragment_x[6]);
  
  	/* wait for processing to complete */
  	while ((readl(&elm_cfg->irqstatus) & (0x1 << poly)) != 0x1)
  		;
  	/* clear status */
  	writel((readl(&elm_cfg->irqstatus) | (0x1 << poly)),
  			&elm_cfg->irqstatus);
  
  	/* check if correctable */
  	location_status = readl(&elm_cfg->error_location[poly].location_status);
  	if (!(location_status & ELM_LOCATION_STATUS_ECC_CORRECTABLE_MASK)) {
  		printf("%s: uncorrectable ECC errors\n", DRIVER_NAME);
  		return -EBADMSG;
  	}
  
  	/* get error count */
  	*error_count = readl(&elm_cfg->error_location[poly].location_status) &
  					ELM_LOCATION_STATUS_ECC_NB_ERRORS_MASK;
  
  	for (i = 0; i < *error_count; i++) {
  		error_locations[i] =
  		     readl(&elm_cfg->error_location[poly].error_location_x[i]);
  	}
  
  	return 0;
  }
  
  
  /**
   * elm_config - Configure ELM module
   * @level: 4 / 8 / 16 bit BCH
   *
   * Configure ELM module based on BCH level.
   * Set mode as continuous mode.
   * Currently we are using only syndrome 0 and syndromes 1 to 6 are not used.
   * Also, the mode is set only for syndrome 0
   */
  int elm_config(enum bch_level level)
  {
  	u32 val;
  	u8 poly = ELM_DEFAULT_POLY;
  	u32 buffer_size = 0x7FF;
  
  	/* config size and level */
  	val = (u32)(level) & ELM_LOCATION_CONFIG_ECC_BCH_LEVEL_MASK;
  	val |= ((buffer_size << ELM_LOCATION_CONFIG_ECC_SIZE_POS) &
  				ELM_LOCATION_CONFIG_ECC_SIZE_MASK);
  	writel(val, &elm_cfg->location_config);
  
  	/* config continous mode */
  	/* enable interrupt generation for syndrome polynomial set */
  	writel((readl(&elm_cfg->irqenable) | (0x1 << poly)),
  			&elm_cfg->irqenable);
  	/* set continuous mode for the syndrome polynomial set */
  	writel((readl(&elm_cfg->page_ctrl) & ~(0x1 << poly)),
  			&elm_cfg->page_ctrl);
  
  	return 0;
  }
  
  /**
   * elm_reset - Do a soft reset of ELM
   *
   * Perform a soft reset of ELM and return after reset is done.
   */
  void elm_reset(void)
  {
  	/* initiate reset */
  	writel((readl(&elm_cfg->sysconfig) | ELM_SYSCONFIG_SOFTRESET),
  			&elm_cfg->sysconfig);
  
  	/* wait for reset complete and normal operation */
  	while ((readl(&elm_cfg->sysstatus) & ELM_SYSSTATUS_RESETDONE) !=
  		ELM_SYSSTATUS_RESETDONE)
  		;
  }
  
  /**
   * elm_init - Initialize ELM module
   *
   * Initialize ELM support. Currently it does only base address init
   * and ELM reset.
   */
  void elm_init(void)
  {
  	elm_cfg = (struct elm *)ELM_BASE;
  	elm_reset();
  }
  