/*
   * Error Location Module
   *
   * Copyright (C) 2012 Texas Instruments Incorporated - http://www.ti.com/
   *
   * This program is free software; you can redistribute it and/or modify
   * it under the terms of the GNU General Public License as published by
   * the Free Software Foundation; either version 2 of the License, or
   * (at your option) any later version.
   *
   * This program is distributed in the hope that it will be useful,
   * but WITHOUT ANY WARRANTY; without even the implied warranty of
   * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
   * GNU General Public License for more details.
   *
   */
  
  #include <linux/platform_device.h>
  #include <linux/module.h>
  #include <linux/interrupt.h>
  #include <linux/io.h>
  #include <linux/of.h>
  #include <linux/sched.h>
  #include <linux/pm_runtime.h>
  #include <linux/platform_data/elm.h>
  
  #define ELM_SYSCONFIG			0x010
  #define ELM_IRQSTATUS			0x018
  #define ELM_IRQENABLE			0x01c
  #define ELM_LOCATION_CONFIG		0x020
  #define ELM_PAGE_CTRL			0x080
  #define ELM_SYNDROME_FRAGMENT_0		0x400
  #define ELM_SYNDROME_FRAGMENT_1		0x404
  #define ELM_SYNDROME_FRAGMENT_2		0x408
  #define ELM_SYNDROME_FRAGMENT_3		0x40c
  #define ELM_SYNDROME_FRAGMENT_4		0x410
  #define ELM_SYNDROME_FRAGMENT_5		0x414
  #define ELM_SYNDROME_FRAGMENT_6		0x418
  #define ELM_LOCATION_STATUS		0x800
  #define ELM_ERROR_LOCATION_0		0x880
  
  /* ELM Interrupt Status Register */
  #define INTR_STATUS_PAGE_VALID		BIT(8)
  
  /* ELM Interrupt Enable Register */
  #define INTR_EN_PAGE_MASK		BIT(8)
  
  /* ELM Location Configuration Register */
  #define ECC_BCH_LEVEL_MASK		0x3
  
  /* ELM syndrome */
  #define ELM_SYNDROME_VALID		BIT(16)
  
  /* ELM_LOCATION_STATUS Register */
  #define ECC_CORRECTABLE_MASK		BIT(8)
  #define ECC_NB_ERRORS_MASK		0x1f
  
  /* ELM_ERROR_LOCATION_0-15 Registers */
  #define ECC_ERROR_LOCATION_MASK		0x1fff
  
  #define ELM_ECC_SIZE			0x7ff
  
  #define SYNDROME_FRAGMENT_REG_SIZE	0x40
  #define ERROR_LOCATION_SIZE		0x100
  
  struct elm_registers {
  	u32 elm_irqenable;
  	u32 elm_sysconfig;
  	u32 elm_location_config;
  	u32 elm_page_ctrl;
  	u32 elm_syndrome_fragment_6[ERROR_VECTOR_MAX];
  	u32 elm_syndrome_fragment_5[ERROR_VECTOR_MAX];
  	u32 elm_syndrome_fragment_4[ERROR_VECTOR_MAX];
  	u32 elm_syndrome_fragment_3[ERROR_VECTOR_MAX];
  	u32 elm_syndrome_fragment_2[ERROR_VECTOR_MAX];
  	u32 elm_syndrome_fragment_1[ERROR_VECTOR_MAX];
  	u32 elm_syndrome_fragment_0[ERROR_VECTOR_MAX];
  };
  
  struct elm_info {
  	struct device *dev;
  	void __iomem *elm_base;
  	struct completion elm_completion;
  	struct list_head list;
  	enum bch_ecc bch_type;
  	struct elm_registers elm_regs;
  };
  
  static LIST_HEAD(elm_devices);
  
  static void elm_write_reg(struct elm_info *info, int offset, u32 val)
  {
  	writel(val, info->elm_base + offset);
  }
  
  static u32 elm_read_reg(struct elm_info *info, int offset)
  {
  	return readl(info->elm_base + offset);
  }
  
  /**
   * elm_config - Configure ELM module
   * @dev:	ELM device
   * @bch_type:	Type of BCH ecc
   */
  int elm_config(struct device *dev, enum bch_ecc bch_type)
  {
  	u32 reg_val;
  	struct elm_info *info = dev_get_drvdata(dev);
  
  	if (!info) {
  		dev_err(dev, "Unable to configure elm - device not probed?
  ");
  		return -ENODEV;
  	}
  
  	reg_val = (bch_type & ECC_BCH_LEVEL_MASK) | (ELM_ECC_SIZE << 16);
  	elm_write_reg(info, ELM_LOCATION_CONFIG, reg_val);
  	info->bch_type = bch_type;
  
  	return 0;
  }
  EXPORT_SYMBOL(elm_config);
  
  /**
   * elm_configure_page_mode - Enable/Disable page mode
   * @info:	elm info
   * @index:	index number of syndrome fragment vector
   * @enable:	enable/disable flag for page mode
   *
   * Enable page mode for syndrome fragment index
   */
  static void elm_configure_page_mode(struct elm_info *info, int index,
  		bool enable)
  {
  	u32 reg_val;
  
  	reg_val = elm_read_reg(info, ELM_PAGE_CTRL);
  	if (enable)
  		reg_val |= BIT(index);	/* enable page mode */
  	else
  		reg_val &= ~BIT(index);	/* disable page mode */
  
  	elm_write_reg(info, ELM_PAGE_CTRL, reg_val);
  }
  
  /**
   * elm_load_syndrome - Load ELM syndrome reg
   * @info:	elm info
   * @err_vec:	elm error vectors
   * @ecc:	buffer with calculated ecc
   *
   * Load syndrome fragment registers with calculated ecc in reverse order.
   */
  static void elm_load_syndrome(struct elm_info *info,
  		struct elm_errorvec *err_vec, u8 *ecc)
  {
  	int i, offset;
  	u32 val;
  
  	for (i = 0; i < ERROR_VECTOR_MAX; i++) {
  
  		/* Check error reported */
  		if (err_vec[i].error_reported) {
  			elm_configure_page_mode(info, i, true);
  			offset = ELM_SYNDROME_FRAGMENT_0 +
  				SYNDROME_FRAGMENT_REG_SIZE * i;
  
  			/* BCH8 */
  			if (info->bch_type) {
  
  				/* syndrome fragment 0 = ecc[9-12B] */
  				val = cpu_to_be32(*(u32 *) &ecc[9]);
  				elm_write_reg(info, offset, val);
  
  				/* syndrome fragment 1 = ecc[5-8B] */
  				offset += 4;
  				val = cpu_to_be32(*(u32 *) &ecc[5]);
  				elm_write_reg(info, offset, val);
  
  				/* syndrome fragment 2 = ecc[1-4B] */
  				offset += 4;
  				val = cpu_to_be32(*(u32 *) &ecc[1]);
  				elm_write_reg(info, offset, val);
  
  				/* syndrome fragment 3 = ecc[0B] */
  				offset += 4;
  				val = ecc[0];
  				elm_write_reg(info, offset, val);
  			} else {
  				/* syndrome fragment 0 = ecc[20-52b] bits */
  				val = (cpu_to_be32(*(u32 *) &ecc[3]) >> 4) |
  					((ecc[2] & 0xf) << 28);
  				elm_write_reg(info, offset, val);
  
  				/* syndrome fragment 1 = ecc[0-20b] bits */
  				offset += 4;
  				val = cpu_to_be32(*(u32 *) &ecc[0]) >> 12;
  				elm_write_reg(info, offset, val);
  			}
  		}
  
  		/* Update ecc pointer with ecc byte size */
  		ecc += info->bch_type ? BCH8_SIZE : BCH4_SIZE;
  	}
  }
  
  /**
   * elm_start_processing - start elm syndrome processing
   * @info:	elm info
   * @err_vec:	elm error vectors
   *
   * Set syndrome valid bit for syndrome fragment registers for which
   * elm syndrome fragment registers are loaded. This enables elm module
   * to start processing syndrome vectors.
   */
  static void elm_start_processing(struct elm_info *info,
  		struct elm_errorvec *err_vec)
  {
  	int i, offset;
  	u32 reg_val;
  
  	/*
  	 * Set syndrome vector valid, so that ELM module
  	 * will process it for vectors error is reported
  	 */
  	for (i = 0; i < ERROR_VECTOR_MAX; i++) {
  		if (err_vec[i].error_reported) {
  			offset = ELM_SYNDROME_FRAGMENT_6 +
  				SYNDROME_FRAGMENT_REG_SIZE * i;
  			reg_val = elm_read_reg(info, offset);
  			reg_val |= ELM_SYNDROME_VALID;
  			elm_write_reg(info, offset, reg_val);
  		}
  	}
  }
  
  /**
   * elm_error_correction - locate correctable error position
   * @info:	elm info
   * @err_vec:	elm error vectors
   *
   * On completion of processing by elm module, error location status
   * register updated with correctable/uncorrectable error information.
   * In case of correctable errors, number of errors located from
   * elm location status register & read the positions from
   * elm error location register.
   */
  static void elm_error_correction(struct elm_info *info,
  		struct elm_errorvec *err_vec)
  {
  	int i, j, errors = 0;
  	int offset;
  	u32 reg_val;
  
  	for (i = 0; i < ERROR_VECTOR_MAX; i++) {
  
  		/* Check error reported */
  		if (err_vec[i].error_reported) {
  			offset = ELM_LOCATION_STATUS + ERROR_LOCATION_SIZE * i;
  			reg_val = elm_read_reg(info, offset);
  
  			/* Check correctable error or not */
  			if (reg_val & ECC_CORRECTABLE_MASK) {
  				offset = ELM_ERROR_LOCATION_0 +
  					ERROR_LOCATION_SIZE * i;
  
  				/* Read count of correctable errors */
  				err_vec[i].error_count = reg_val &
  					ECC_NB_ERRORS_MASK;
  
  				/* Update the error locations in error vector */
  				for (j = 0; j < err_vec[i].error_count; j++) {
  
  					reg_val = elm_read_reg(info, offset);
  					err_vec[i].error_loc[j] = reg_val &
  						ECC_ERROR_LOCATION_MASK;
  
  					/* Update error location register */
  					offset += 4;
  				}
  
  				errors += err_vec[i].error_count;
  			} else {
  				err_vec[i].error_uncorrectable = true;
  			}
  
  			/* Clearing interrupts for processed error vectors */
  			elm_write_reg(info, ELM_IRQSTATUS, BIT(i));
  
  			/* Disable page mode */
  			elm_configure_page_mode(info, i, false);
  		}
  	}
  }
  
  /**
   * elm_decode_bch_error_page - Locate error position
   * @dev:	device pointer
   * @ecc_calc:	calculated ECC bytes from GPMC
   * @err_vec:	elm error vectors
   *
   * Called with one or more error reported vectors & vectors with
   * error reported is updated in err_vec[].error_reported
   */
  void elm_decode_bch_error_page(struct device *dev, u8 *ecc_calc,
  		struct elm_errorvec *err_vec)
  {
  	struct elm_info *info = dev_get_drvdata(dev);
  	u32 reg_val;
  
  	/* Enable page mode interrupt */
  	reg_val = elm_read_reg(info, ELM_IRQSTATUS);
  	elm_write_reg(info, ELM_IRQSTATUS, reg_val & INTR_STATUS_PAGE_VALID);
  	elm_write_reg(info, ELM_IRQENABLE, INTR_EN_PAGE_MASK);
  
  	/* Load valid ecc byte to syndrome fragment register */
  	elm_load_syndrome(info, err_vec, ecc_calc);
  
  	/* Enable syndrome processing for which syndrome fragment is updated */
  	elm_start_processing(info, err_vec);
  
  	/* Wait for ELM module to finish locating error correction */
  	wait_for_completion(&info->elm_completion);
  
  	/* Disable page mode interrupt */
  	reg_val = elm_read_reg(info, ELM_IRQENABLE);
  	elm_write_reg(info, ELM_IRQENABLE, reg_val & ~INTR_EN_PAGE_MASK);
  	elm_error_correction(info, err_vec);
  }
  EXPORT_SYMBOL(elm_decode_bch_error_page);
  
  static irqreturn_t elm_isr(int this_irq, void *dev_id)
  {
  	u32 reg_val;
  	struct elm_info *info = dev_id;
  
  	reg_val = elm_read_reg(info, ELM_IRQSTATUS);
  
  	/* All error vectors processed */
  	if (reg_val & INTR_STATUS_PAGE_VALID) {
  		elm_write_reg(info, ELM_IRQSTATUS,
  				reg_val & INTR_STATUS_PAGE_VALID);
  		complete(&info->elm_completion);
  		return IRQ_HANDLED;
  	}
  
  	return IRQ_NONE;
  }
  
  static int elm_probe(struct platform_device *pdev)
  {
  	int ret = 0;
  	struct resource *res, *irq;
  	struct elm_info *info;
  
  	info = devm_kzalloc(&pdev->dev, sizeof(*info), GFP_KERNEL);
  	if (!info) {
  		dev_err(&pdev->dev, "failed to allocate memory
  ");
  		return -ENOMEM;
  	}
  
  	info->dev = &pdev->dev;
  
  	irq = platform_get_resource(pdev, IORESOURCE_IRQ, 0);
  	if (!irq) {
  		dev_err(&pdev->dev, "no irq resource defined
  ");
  		return -ENODEV;
  	}
  
  	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
  	info->elm_base = devm_ioremap_resource(&pdev->dev, res);
  	if (IS_ERR(info->elm_base))
  		return PTR_ERR(info->elm_base);
  
  	ret = devm_request_irq(&pdev->dev, irq->start, elm_isr, 0,
  			pdev->name, info);
  	if (ret) {
  		dev_err(&pdev->dev, "failure requesting irq %i
  ", irq->start);
  		return ret;
  	}
  
  	pm_runtime_enable(&pdev->dev);
  	if (pm_runtime_get_sync(&pdev->dev)) {
  		ret = -EINVAL;
  		pm_runtime_disable(&pdev->dev);
  		dev_err(&pdev->dev, "can't enable clock
  ");
  		return ret;
  	}
  
  	init_completion(&info->elm_completion);
  	INIT_LIST_HEAD(&info->list);
  	list_add(&info->list, &elm_devices);
  	platform_set_drvdata(pdev, info);
  	return ret;
  }
  
  static int elm_remove(struct platform_device *pdev)
  {
  	pm_runtime_put_sync(&pdev->dev);
  	pm_runtime_disable(&pdev->dev);
  	return 0;
  }
  
  /**
   * elm_context_save
   * saves ELM configurations to preserve them across Hardware powered-down
   */
  static int elm_context_save(struct elm_info *info)
  {
  	struct elm_registers *regs = &info->elm_regs;
  	enum bch_ecc bch_type = info->bch_type;
  	u32 offset = 0, i;
  
  	regs->elm_irqenable       = elm_read_reg(info, ELM_IRQENABLE);
  	regs->elm_sysconfig       = elm_read_reg(info, ELM_SYSCONFIG);
  	regs->elm_location_config = elm_read_reg(info, ELM_LOCATION_CONFIG);
  	regs->elm_page_ctrl       = elm_read_reg(info, ELM_PAGE_CTRL);
  	for (i = 0; i < ERROR_VECTOR_MAX; i++) {
  		offset = i * SYNDROME_FRAGMENT_REG_SIZE;
  		switch (bch_type) {
  		case BCH8_ECC:
  			regs->elm_syndrome_fragment_3[i] = elm_read_reg(info,
  					ELM_SYNDROME_FRAGMENT_3 + offset);
  			regs->elm_syndrome_fragment_2[i] = elm_read_reg(info,
  					ELM_SYNDROME_FRAGMENT_2 + offset);
  		case BCH4_ECC:
  			regs->elm_syndrome_fragment_1[i] = elm_read_reg(info,
  					ELM_SYNDROME_FRAGMENT_1 + offset);
  			regs->elm_syndrome_fragment_0[i] = elm_read_reg(info,
  					ELM_SYNDROME_FRAGMENT_0 + offset);
  			break;
  		default:
  			return -EINVAL;
  		}
  		/* ELM SYNDROME_VALID bit in SYNDROME_FRAGMENT_6[] needs
  		 * to be saved for all BCH schemes*/
  		regs->elm_syndrome_fragment_6[i] = elm_read_reg(info,
  					ELM_SYNDROME_FRAGMENT_6 + offset);
  	}
  	return 0;
  }
  
  /**
   * elm_context_restore
   * writes configurations saved duing power-down back into ELM registers
   */
  static int elm_context_restore(struct elm_info *info)
  {
  	struct elm_registers *regs = &info->elm_regs;
  	enum bch_ecc bch_type = info->bch_type;
  	u32 offset = 0, i;
  
  	elm_write_reg(info, ELM_IRQENABLE,	 regs->elm_irqenable);
  	elm_write_reg(info, ELM_SYSCONFIG,	 regs->elm_sysconfig);
  	elm_write_reg(info, ELM_LOCATION_CONFIG, regs->elm_location_config);
  	elm_write_reg(info, ELM_PAGE_CTRL,	 regs->elm_page_ctrl);
  	for (i = 0; i < ERROR_VECTOR_MAX; i++) {
  		offset = i * SYNDROME_FRAGMENT_REG_SIZE;
  		switch (bch_type) {
  		case BCH8_ECC:
  			elm_write_reg(info, ELM_SYNDROME_FRAGMENT_3 + offset,
  					regs->elm_syndrome_fragment_3[i]);
  			elm_write_reg(info, ELM_SYNDROME_FRAGMENT_2 + offset,
  					regs->elm_syndrome_fragment_2[i]);
  		case BCH4_ECC:
  			elm_write_reg(info, ELM_SYNDROME_FRAGMENT_1 + offset,
  					regs->elm_syndrome_fragment_1[i]);
  			elm_write_reg(info, ELM_SYNDROME_FRAGMENT_0 + offset,
  					regs->elm_syndrome_fragment_0[i]);
  			break;
  		default:
  			return -EINVAL;
  		}
  		/* ELM_SYNDROME_VALID bit to be set in last to trigger FSM */
  		elm_write_reg(info, ELM_SYNDROME_FRAGMENT_6 + offset,
  					regs->elm_syndrome_fragment_6[i] &
  							 ELM_SYNDROME_VALID);
  	}
  	return 0;
  }
  
  static int elm_suspend(struct device *dev)
  {
  	struct elm_info *info = dev_get_drvdata(dev);
  	elm_context_save(info);
  	pm_runtime_put_sync(dev);
  	return 0;
  }
  
  static int elm_resume(struct device *dev)
  {
  	struct elm_info *info = dev_get_drvdata(dev);
  	pm_runtime_get_sync(dev);
  	elm_context_restore(info);
  	return 0;
  }
  
  static SIMPLE_DEV_PM_OPS(elm_pm_ops, elm_suspend, elm_resume);
  
  #ifdef CONFIG_OF
  static const struct of_device_id elm_of_match[] = {
  	{ .compatible = "ti,am3352-elm" },
  	{},
  };
  MODULE_DEVICE_TABLE(of, elm_of_match);
  #endif
  
  static struct platform_driver elm_driver = {
  	.driver	= {
  		.name	= "elm",
  		.owner	= THIS_MODULE,
  		.of_match_table = of_match_ptr(elm_of_match),
  		.pm	= &elm_pm_ops,
  	},
  	.probe	= elm_probe,
  	.remove	= elm_remove,
  };
  
  module_platform_driver(elm_driver);
  
  MODULE_DESCRIPTION("ELM driver for BCH error correction");
  MODULE_AUTHOR("Texas Instruments");
  MODULE_ALIAS("platform: elm");
  MODULE_LICENSE("GPL v2");