// SPDX-License-Identifier: GPL-2.0-or-later
/*
 * Error Location Module
 *
 * Copyright (C) 2012 Texas Instruments Incorporated - https://www.ti.com/
 */

#define DRIVER_NAME     "omap-elm"

#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;
        int ecc_steps;
        int ecc_syndrome_size;
};

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
 * @ecc_steps:  ECC steps to assign to config
 * @ecc_step_size:      ECC step size to assign to config
 * @ecc_syndrome_size:  ECC syndrome size to assign to config
 */
int elm_config(struct device *dev, enum bch_ecc bch_type,
        int ecc_steps, int ecc_step_size, int ecc_syndrome_size)
{
        u32 reg_val;
        struct elm_info *info = dev_get_drvdata(dev);

        if (!info) {
                dev_err(dev, "Unable to configure elm - device not probed?\n");
                return -EPROBE_DEFER;
        }
        /* ELM cannot detect ECC errors for chunks > 1KB */
        if (ecc_step_size > ((ELM_ECC_SIZE + 1) / 2)) {
                dev_err(dev, "unsupported config ecc-size=%d\n", ecc_step_size);
                return -EINVAL;
        }
        /* ELM support 8 error syndrome process */
        if (ecc_steps > ERROR_VECTOR_MAX && ecc_steps % ERROR_VECTOR_MAX) {
                dev_err(dev, "unsupported config ecc-step=%d\n", ecc_steps);
                return -EINVAL;
        }

        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;
        info->ecc_steps         = ecc_steps;
        info->ecc_syndrome_size = ecc_syndrome_size;

        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 < info->ecc_steps; 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;
                        switch (info->bch_type) {
                        case BCH8_ECC:
                                /* syndrome fragment 0 = ecc[9-12B] */
                                val = (__force u32)cpu_to_be32(*(u32 *)&ecc[9]);
                                elm_write_reg(info, offset, val);

                                /* syndrome fragment 1 = ecc[5-8B] */
                                offset += 4;
                                val = (__force u32)cpu_to_be32(*(u32 *)&ecc[5]);
                                elm_write_reg(info, offset, val);

                                /* syndrome fragment 2 = ecc[1-4B] */
                                offset += 4;
                                val = (__force u32)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);
                                break;
                        case BCH4_ECC:
                                /* syndrome fragment 0 = ecc[20-52b] bits */
                                val = ((__force u32)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 = (__force u32)cpu_to_be32(*(u32 *)&ecc[0]) >> 12;
                                elm_write_reg(info, offset, val);
                                break;
                        case BCH16_ECC:
                                val = (__force u32)cpu_to_be32(*(u32 *)&ecc[22]);
                                elm_write_reg(info, offset, val);
                                offset += 4;
                                val = (__force u32)cpu_to_be32(*(u32 *)&ecc[18]);
                                elm_write_reg(info, offset, val);
                                offset += 4;
                                val = (__force u32)cpu_to_be32(*(u32 *)&ecc[14]);
                                elm_write_reg(info, offset, val);
                                offset += 4;
                                val = (__force u32)cpu_to_be32(*(u32 *)&ecc[10]);
                                elm_write_reg(info, offset, val);
                                offset += 4;
                                val = (__force u32)cpu_to_be32(*(u32 *)&ecc[6]);
                                elm_write_reg(info, offset, val);
                                offset += 4;
                                val = (__force u32)cpu_to_be32(*(u32 *)&ecc[2]);
                                elm_write_reg(info, offset, val);
                                offset += 4;
                                val = (__force u32)cpu_to_be32(*(u32 *)&ecc[0]) >> 16;
                                elm_write_reg(info, offset, val);
                                break;
                        default:
                                pr_err("invalid config bch_type\n");
                        }
                }

                /* Update ecc pointer with ecc byte size */
                ecc += info->ecc_syndrome_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 < info->ecc_steps; 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;
        int offset;
        u32 reg_val;

        for (i = 0; i < info->ecc_steps; 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;
                                }
                        } 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 elm_info *info;
        int irq;

        info = devm_kzalloc(&pdev->dev, sizeof(*info), GFP_KERNEL);
        if (!info)
                return -ENOMEM;

        info->dev = &pdev->dev;

        irq = platform_get_irq(pdev, 0);
        if (irq < 0)
                return irq;

        info->elm_base = devm_platform_ioremap_resource(pdev, 0);
        if (IS_ERR(info->elm_base))
                return PTR_ERR(info->elm_base);

        ret = devm_request_irq(&pdev->dev, irq, elm_isr, 0,
                               pdev->name, info);
        if (ret) {
                dev_err(&pdev->dev, "failure requesting %d\n", irq);
                return ret;
        }

        pm_runtime_enable(&pdev->dev);
        if (pm_runtime_get_sync(&pdev->dev) < 0) {
                ret = -EINVAL;
                pm_runtime_put_sync(&pdev->dev);
                pm_runtime_disable(&pdev->dev);
                dev_err(&pdev->dev, "can't enable clock\n");
                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 void elm_remove(struct platform_device *pdev)
{
        pm_runtime_put_sync(&pdev->dev);
        pm_runtime_disable(&pdev->dev);
}

#ifdef CONFIG_PM_SLEEP
/*
 * 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 BCH16_ECC:
                        regs->elm_syndrome_fragment_6[i] = elm_read_reg(info,
                                        ELM_SYNDROME_FRAGMENT_6 + offset);
                        regs->elm_syndrome_fragment_5[i] = elm_read_reg(info,
                                        ELM_SYNDROME_FRAGMENT_5 + offset);
                        regs->elm_syndrome_fragment_4[i] = elm_read_reg(info,
                                        ELM_SYNDROME_FRAGMENT_4 + offset);
                        fallthrough;
                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);
                        fallthrough;
                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 BCH16_ECC:
                        elm_write_reg(info, ELM_SYNDROME_FRAGMENT_6 + offset,
                                        regs->elm_syndrome_fragment_6[i]);
                        elm_write_reg(info, ELM_SYNDROME_FRAGMENT_5 + offset,
                                        regs->elm_syndrome_fragment_5[i]);
                        elm_write_reg(info, ELM_SYNDROME_FRAGMENT_4 + offset,
                                        regs->elm_syndrome_fragment_4[i]);
                        fallthrough;
                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]);
                        fallthrough;
                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;
}
#endif

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" },
        { .compatible = "ti,am64-elm" },
        {},
};
MODULE_DEVICE_TABLE(of, elm_of_match);
#endif

static struct platform_driver elm_driver = {
        .driver = {
                .name   = DRIVER_NAME,
                .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:" DRIVER_NAME);
MODULE_LICENSE("GPL v2");