/*
 * Oxford Semiconductor OXNAS NAND driver

 * Copyright (C) 2016 Neil Armstrong <narmstrong@baylibre.com>
 * Heavily based on plat_nand.c :
 * Author: Vitaly Wool <vitalywool@gmail.com>
 * Copyright (C) 2013 Ma Haijun <mahaijuns@gmail.com>
 * Copyright (C) 2012 John Crispin <blogic@openwrt.org>
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation.
 *
 */

#include <linux/err.h>
#include <linux/io.h>
#include <linux/module.h>
#include <linux/platform_device.h>
#include <linux/slab.h>
#include <linux/clk.h>
#include <linux/reset.h>
#include <linux/mtd/mtd.h>
#include <linux/mtd/rawnand.h>
#include <linux/mtd/partitions.h>
#include <linux/of.h>

/* Nand commands */
#define OXNAS_NAND_CMD_ALE              BIT(18)
#define OXNAS_NAND_CMD_CLE              BIT(19)

#define OXNAS_NAND_MAX_CHIPS    1

struct oxnas_nand_ctrl {
        struct nand_hw_control base;
        void __iomem *io_base;
        struct clk *clk;
        struct nand_chip *chips[OXNAS_NAND_MAX_CHIPS];
};

static uint8_t oxnas_nand_read_byte(struct mtd_info *mtd)
{
        struct nand_chip *chip = mtd_to_nand(mtd);
        struct oxnas_nand_ctrl *oxnas = nand_get_controller_data(chip);

        return readb(oxnas->io_base);
}

static void oxnas_nand_read_buf(struct mtd_info *mtd, u8 *buf, int len)
{
        struct nand_chip *chip = mtd_to_nand(mtd);
        struct oxnas_nand_ctrl *oxnas = nand_get_controller_data(chip);

        ioread8_rep(oxnas->io_base, buf, len);
}

static void oxnas_nand_write_buf(struct mtd_info *mtd, const u8 *buf, int len)
{
        struct nand_chip *chip = mtd_to_nand(mtd);
        struct oxnas_nand_ctrl *oxnas = nand_get_controller_data(chip);

        iowrite8_rep(oxnas->io_base, buf, len);
}

/* Single CS command control */
static void oxnas_nand_cmd_ctrl(struct mtd_info *mtd, int cmd,
                                unsigned int ctrl)
{
        struct nand_chip *chip = mtd_to_nand(mtd);
        struct oxnas_nand_ctrl *oxnas = nand_get_controller_data(chip);

        if (ctrl & NAND_CLE)
                writeb(cmd, oxnas->io_base + OXNAS_NAND_CMD_CLE);
        else if (ctrl & NAND_ALE)
                writeb(cmd, oxnas->io_base + OXNAS_NAND_CMD_ALE);
}

/*
 * Probe for the NAND device.
 */
static int oxnas_nand_probe(struct platform_device *pdev)
{
        struct device_node *np = pdev->dev.of_node;
        struct device_node *nand_np;
        struct oxnas_nand_ctrl *oxnas;
        struct nand_chip *chip;
        struct mtd_info *mtd;
        struct resource *res;
        int nchips = 0;
        int count = 0;
        int err = 0;

        /* Allocate memory for the device structure (and zero it) */
        oxnas = devm_kzalloc(&pdev->dev, sizeof(*oxnas),
                             GFP_KERNEL);
        if (!oxnas)
                return -ENOMEM;

        nand_hw_control_init(&oxnas->base);

        res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
        oxnas->io_base = devm_ioremap_resource(&pdev->dev, res);
        if (IS_ERR(oxnas->io_base))
                return PTR_ERR(oxnas->io_base);

        oxnas->clk = devm_clk_get(&pdev->dev, NULL);
        if (IS_ERR(oxnas->clk))
                oxnas->clk = NULL;

        /* Only a single chip node is supported */
        count = of_get_child_count(np);
        if (count > 1)
                return -EINVAL;

        err = clk_prepare_enable(oxnas->clk);
        if (err)
                return err;

        device_reset_optional(&pdev->dev);

        for_each_child_of_node(np, nand_np) {
                chip = devm_kzalloc(&pdev->dev, sizeof(struct nand_chip),
                                    GFP_KERNEL);
                if (!chip) {
                        err = -ENOMEM;
                        goto err_clk_unprepare;
                }

                chip->controller = &oxnas->base;

                nand_set_flash_node(chip, nand_np);
                nand_set_controller_data(chip, oxnas);

                mtd = nand_to_mtd(chip);
                mtd->dev.parent = &pdev->dev;
                mtd->priv = chip;

                chip->cmd_ctrl = oxnas_nand_cmd_ctrl;
                chip->read_buf = oxnas_nand_read_buf;
                chip->read_byte = oxnas_nand_read_byte;
                chip->write_buf = oxnas_nand_write_buf;
                chip->chip_delay = 30;

                /* Scan to find existence of the device */
                err = nand_scan(mtd, 1);
                if (err)
                        goto err_clk_unprepare;

                err = mtd_device_register(mtd, NULL, 0);
                if (err) {
                        nand_release(mtd);
                        goto err_clk_unprepare;
                }

                oxnas->chips[nchips] = chip;
                ++nchips;
        }

        /* Exit if no chips found */
        if (!nchips) {
                err = -ENODEV;
                goto err_clk_unprepare;
        }

        platform_set_drvdata(pdev, oxnas);

        return 0;

err_clk_unprepare:
        clk_disable_unprepare(oxnas->clk);
        return err;
}

static int oxnas_nand_remove(struct platform_device *pdev)
{
        struct oxnas_nand_ctrl *oxnas = platform_get_drvdata(pdev);

        if (oxnas->chips[0])
                nand_release(nand_to_mtd(oxnas->chips[0]));

        clk_disable_unprepare(oxnas->clk);

        return 0;
}

static const struct of_device_id oxnas_nand_match[] = {
        { .compatible = "oxsemi,ox820-nand" },
        {},
};
MODULE_DEVICE_TABLE(of, oxnas_nand_match);

static struct platform_driver oxnas_nand_driver = {
        .probe  = oxnas_nand_probe,
        .remove = oxnas_nand_remove,
        .driver = {
                .name           = "oxnas_nand",
                .of_match_table = oxnas_nand_match,
        },
};

module_platform_driver(oxnas_nand_driver);

MODULE_LICENSE("GPL");
MODULE_AUTHOR("Neil Armstrong <narmstrong@baylibre.com>");
MODULE_DESCRIPTION("Oxnas NAND driver");
MODULE_ALIAS("platform:oxnas_nand");