// SPDX-License-Identifier: GPL-2.0-only
/*
 * Updated, and converted to generic GPIO based driver by Russell King.
 *
 * Written by Ben Dooks <ben@simtec.co.uk>
 *   Based on 2.4 version by Mark Whittaker
 *
 * © 2004 Simtec Electronics
 *
 * Device driver for NAND flash that uses a memory mapped interface to
 * read/write the NAND commands and data, and GPIO pins for control signals
 * (the DT binding refers to this as "GPIO assisted NAND flash")
 */

#include <linux/kernel.h>
#include <linux/err.h>
#include <linux/slab.h>
#include <linux/module.h>
#include <linux/platform_device.h>
#include <linux/gpio/consumer.h>
#include <linux/io.h>
#include <linux/mtd/mtd.h>
#include <linux/mtd/rawnand.h>
#include <linux/mtd/partitions.h>
#include <linux/mtd/nand-gpio.h>
#include <linux/of.h>
#include <linux/of_address.h>
#include <linux/delay.h>

struct gpiomtd {
        struct nand_controller  base;
        void __iomem            *io;
        void __iomem            *io_sync;
        struct nand_chip        nand_chip;
        struct gpio_nand_platdata plat;
        struct gpio_desc *nce; /* Optional chip enable */
        struct gpio_desc *cle;
        struct gpio_desc *ale;
        struct gpio_desc *rdy;
        struct gpio_desc *nwp; /* Optional write protection */
};

static inline struct gpiomtd *gpio_nand_getpriv(struct mtd_info *mtd)
{
        return container_of(mtd_to_nand(mtd), struct gpiomtd, nand_chip);
}


#ifdef CONFIG_ARM
/* gpio_nand_dosync()
 *
 * Make sure the GPIO state changes occur in-order with writes to NAND
 * memory region.
 * Needed on PXA due to bus-reordering within the SoC itself (see section on
 * I/O ordering in PXA manual (section 2.3, p35)
 */
static void gpio_nand_dosync(struct gpiomtd *gpiomtd)
{
        unsigned long tmp;

        if (gpiomtd->io_sync) {
                /*
                 * Linux memory barriers don't cater for what's required here.
                 * What's required is what's here - a read from a separate
                 * region with a dependency on that read.
                 */
                tmp = readl(gpiomtd->io_sync);
                asm volatile("mov %1, %0\n" : "=r" (tmp) : "r" (tmp));
        }
}
#else
static inline void gpio_nand_dosync(struct gpiomtd *gpiomtd) {}
#endif

static int gpio_nand_exec_instr(struct nand_chip *chip,
                                const struct nand_op_instr *instr)
{
        struct gpiomtd *gpiomtd = gpio_nand_getpriv(nand_to_mtd(chip));
        unsigned int i;

        switch (instr->type) {
        case NAND_OP_CMD_INSTR:
                gpio_nand_dosync(gpiomtd);
                gpiod_set_value(gpiomtd->cle, 1);
                gpio_nand_dosync(gpiomtd);
                writeb(instr->ctx.cmd.opcode, gpiomtd->io);
                gpio_nand_dosync(gpiomtd);
                gpiod_set_value(gpiomtd->cle, 0);
                return 0;

        case NAND_OP_ADDR_INSTR:
                gpio_nand_dosync(gpiomtd);
                gpiod_set_value(gpiomtd->ale, 1);
                gpio_nand_dosync(gpiomtd);
                for (i = 0; i < instr->ctx.addr.naddrs; i++)
                        writeb(instr->ctx.addr.addrs[i], gpiomtd->io);
                gpio_nand_dosync(gpiomtd);
                gpiod_set_value(gpiomtd->ale, 0);
                return 0;

        case NAND_OP_DATA_IN_INSTR:
                gpio_nand_dosync(gpiomtd);
                if ((chip->options & NAND_BUSWIDTH_16) &&
                    !instr->ctx.data.force_8bit)
                        ioread16_rep(gpiomtd->io, instr->ctx.data.buf.in,
                                     instr->ctx.data.len / 2);
                else
                        ioread8_rep(gpiomtd->io, instr->ctx.data.buf.in,
                                    instr->ctx.data.len);
                return 0;

        case NAND_OP_DATA_OUT_INSTR:
                gpio_nand_dosync(gpiomtd);
                if ((chip->options & NAND_BUSWIDTH_16) &&
                    !instr->ctx.data.force_8bit)
                        iowrite16_rep(gpiomtd->io, instr->ctx.data.buf.out,
                                      instr->ctx.data.len / 2);
                else
                        iowrite8_rep(gpiomtd->io, instr->ctx.data.buf.out,
                                     instr->ctx.data.len);
                return 0;

        case NAND_OP_WAITRDY_INSTR:
                if (!gpiomtd->rdy)
                        return nand_soft_waitrdy(chip, instr->ctx.waitrdy.timeout_ms);

                return nand_gpio_waitrdy(chip, gpiomtd->rdy,
                                         instr->ctx.waitrdy.timeout_ms);

        default:
                return -EINVAL;
        }

        return 0;
}

static int gpio_nand_exec_op(struct nand_chip *chip,
                             const struct nand_operation *op,
                             bool check_only)
{
        struct gpiomtd *gpiomtd = gpio_nand_getpriv(nand_to_mtd(chip));
        unsigned int i;
        int ret = 0;

        if (check_only)
                return 0;

        gpio_nand_dosync(gpiomtd);
        gpiod_set_value(gpiomtd->nce, 0);
        for (i = 0; i < op->ninstrs; i++) {
                ret = gpio_nand_exec_instr(chip, &op->instrs[i]);
                if (ret)
                        break;

                if (op->instrs[i].delay_ns)
                        ndelay(op->instrs[i].delay_ns);
        }
        gpio_nand_dosync(gpiomtd);
        gpiod_set_value(gpiomtd->nce, 1);

        return ret;
}

static int gpio_nand_attach_chip(struct nand_chip *chip)
{
        if (chip->ecc.engine_type == NAND_ECC_ENGINE_TYPE_SOFT &&
            chip->ecc.algo == NAND_ECC_ALGO_UNKNOWN)
                chip->ecc.algo = NAND_ECC_ALGO_HAMMING;

        return 0;
}

static const struct nand_controller_ops gpio_nand_ops = {
        .exec_op = gpio_nand_exec_op,
        .attach_chip = gpio_nand_attach_chip,
};

#ifdef CONFIG_OF
static const struct of_device_id gpio_nand_id_table[] = {
        { .compatible = "gpio-control-nand" },
        {}
};
MODULE_DEVICE_TABLE(of, gpio_nand_id_table);

static int gpio_nand_get_config_of(const struct device *dev,
                                   struct gpio_nand_platdata *plat)
{
        u32 val;

        if (!dev->of_node)
                return -ENODEV;

        if (!of_property_read_u32(dev->of_node, "bank-width", &val)) {
                if (val == 2) {
                        plat->options |= NAND_BUSWIDTH_16;
                } else if (val != 1) {
                        dev_err(dev, "invalid bank-width %u\n", val);
                        return -EINVAL;
                }
        }

        if (!of_property_read_u32(dev->of_node, "chip-delay", &val))
                plat->chip_delay = val;

        return 0;
}

static struct resource *gpio_nand_get_io_sync_of(struct platform_device *pdev)
{
        struct resource *r;
        u64 addr;

        if (of_property_read_u64(pdev->dev.of_node,
                                       "gpio-control-nand,io-sync-reg", &addr))
                return NULL;

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

        r->start = addr;
        r->end = r->start + 0x3;
        r->flags = IORESOURCE_MEM;

        return r;
}
#else /* CONFIG_OF */
static inline int gpio_nand_get_config_of(const struct device *dev,
                                          struct gpio_nand_platdata *plat)
{
        return -ENOSYS;
}

static inline struct resource *
gpio_nand_get_io_sync_of(struct platform_device *pdev)
{
        return NULL;
}
#endif /* CONFIG_OF */

static inline int gpio_nand_get_config(const struct device *dev,
                                       struct gpio_nand_platdata *plat)
{
        int ret = gpio_nand_get_config_of(dev, plat);

        if (!ret)
                return ret;

        if (dev_get_platdata(dev)) {
                memcpy(plat, dev_get_platdata(dev), sizeof(*plat));
                return 0;
        }

        return -EINVAL;
}

static inline struct resource *
gpio_nand_get_io_sync(struct platform_device *pdev)
{
        struct resource *r = gpio_nand_get_io_sync_of(pdev);

        if (r)
                return r;

        return platform_get_resource(pdev, IORESOURCE_MEM, 1);
}

static void gpio_nand_remove(struct platform_device *pdev)
{
        struct gpiomtd *gpiomtd = platform_get_drvdata(pdev);
        struct nand_chip *chip = &gpiomtd->nand_chip;
        int ret;

        ret = mtd_device_unregister(nand_to_mtd(chip));
        WARN_ON(ret);
        nand_cleanup(chip);

        /* Enable write protection and disable the chip */
        if (gpiomtd->nwp && !IS_ERR(gpiomtd->nwp))
                gpiod_set_value(gpiomtd->nwp, 0);
        if (gpiomtd->nce && !IS_ERR(gpiomtd->nce))
                gpiod_set_value(gpiomtd->nce, 0);
}

static int gpio_nand_probe(struct platform_device *pdev)
{
        struct gpiomtd *gpiomtd;
        struct nand_chip *chip;
        struct mtd_info *mtd;
        struct resource *res;
        struct device *dev = &pdev->dev;
        int ret = 0;

        if (!dev->of_node && !dev_get_platdata(dev))
                return -EINVAL;

        gpiomtd = devm_kzalloc(dev, sizeof(*gpiomtd), GFP_KERNEL);
        if (!gpiomtd)
                return -ENOMEM;

        chip = &gpiomtd->nand_chip;

        gpiomtd->io = devm_platform_ioremap_resource(pdev, 0);
        if (IS_ERR(gpiomtd->io))
                return PTR_ERR(gpiomtd->io);

        res = gpio_nand_get_io_sync(pdev);
        if (res) {
                gpiomtd->io_sync = devm_ioremap_resource(dev, res);
                if (IS_ERR(gpiomtd->io_sync))
                        return PTR_ERR(gpiomtd->io_sync);
        }

        ret = gpio_nand_get_config(dev, &gpiomtd->plat);
        if (ret)
                return ret;

        /* Just enable the chip */
        gpiomtd->nce = devm_gpiod_get_optional(dev, "nce", GPIOD_OUT_HIGH);
        if (IS_ERR(gpiomtd->nce))
                return PTR_ERR(gpiomtd->nce);

        /* We disable write protection once we know probe() will succeed */
        gpiomtd->nwp = devm_gpiod_get_optional(dev, "nwp", GPIOD_OUT_LOW);
        if (IS_ERR(gpiomtd->nwp)) {
                ret = PTR_ERR(gpiomtd->nwp);
                goto out_ce;
        }

        gpiomtd->ale = devm_gpiod_get(dev, "ale", GPIOD_OUT_LOW);
        if (IS_ERR(gpiomtd->ale)) {
                ret = PTR_ERR(gpiomtd->ale);
                goto out_ce;
        }

        gpiomtd->cle = devm_gpiod_get(dev, "cle", GPIOD_OUT_LOW);
        if (IS_ERR(gpiomtd->cle)) {
                ret = PTR_ERR(gpiomtd->cle);
                goto out_ce;
        }

        gpiomtd->rdy = devm_gpiod_get_optional(dev, "rdy", GPIOD_IN);
        if (IS_ERR(gpiomtd->rdy)) {
                ret = PTR_ERR(gpiomtd->rdy);
                goto out_ce;
        }

        nand_controller_init(&gpiomtd->base);
        gpiomtd->base.ops = &gpio_nand_ops;

        nand_set_flash_node(chip, pdev->dev.of_node);
        chip->options           = gpiomtd->plat.options;
        chip->controller        = &gpiomtd->base;

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

        platform_set_drvdata(pdev, gpiomtd);

        /* Disable write protection, if wired up */
        if (gpiomtd->nwp && !IS_ERR(gpiomtd->nwp))
                gpiod_direction_output(gpiomtd->nwp, 1);

        /*
         * This driver assumes that the default ECC engine should be TYPE_SOFT.
         * Set ->engine_type before registering the NAND devices in order to
         * provide a driver specific default value.
         */
        chip->ecc.engine_type = NAND_ECC_ENGINE_TYPE_SOFT;

        ret = nand_scan(chip, 1);
        if (ret)
                goto err_wp;

        if (gpiomtd->plat.adjust_parts)
                gpiomtd->plat.adjust_parts(&gpiomtd->plat, mtd->size);

        ret = mtd_device_register(mtd, gpiomtd->plat.parts,
                                  gpiomtd->plat.num_parts);
        if (!ret)
                return 0;

err_wp:
        if (gpiomtd->nwp && !IS_ERR(gpiomtd->nwp))
                gpiod_set_value(gpiomtd->nwp, 0);
out_ce:
        if (gpiomtd->nce && !IS_ERR(gpiomtd->nce))
                gpiod_set_value(gpiomtd->nce, 0);

        return ret;
}

static struct platform_driver gpio_nand_driver = {
        .probe          = gpio_nand_probe,
        .remove         = gpio_nand_remove,
        .driver         = {
                .name   = "gpio-nand",
                .of_match_table = of_match_ptr(gpio_nand_id_table),
        },
};

module_platform_driver(gpio_nand_driver);

MODULE_LICENSE("GPL");
MODULE_AUTHOR("Ben Dooks <ben@simtec.co.uk>");
MODULE_DESCRIPTION("GPIO NAND Driver");