// SPDX-License-Identifier: GPL-2.0
/*
 * Cortina Systems Gemini OF physmap add-on
 * Copyright (C) 2017 Linus Walleij <linus.walleij@linaro.org>
 *
 * This SoC has an elaborate flash control register, so we need to
 * detect and set it up when booting on this platform.
 */
#include <linux/export.h>
#include <linux/of.h>
#include <linux/mtd/map.h>
#include <linux/mtd/xip.h>
#include <linux/mfd/syscon.h>
#include <linux/platform_device.h>
#include <linux/regmap.h>
#include <linux/bitops.h>
#include <linux/pinctrl/consumer.h>
#include "physmap-gemini.h"

/*
 * The Flash-relevant parts of the global status register
 * These would also be relevant for a NAND driver.
 */
#define GLOBAL_STATUS                   0x04
#define FLASH_TYPE_MASK                 (0x3 << 24)
#define FLASH_TYPE_NAND_2K              (0x3 << 24)
#define FLASH_TYPE_NAND_512             (0x2 << 24)
#define FLASH_TYPE_PARALLEL             (0x1 << 24)
#define FLASH_TYPE_SERIAL               (0x0 << 24)
/* if parallel */
#define FLASH_WIDTH_16BIT               (1 << 23)       /* else 8 bit */
/* if serial */
#define FLASH_ATMEL                     (1 << 23)       /* else STM */

#define FLASH_SIZE_MASK                 (0x3 << 21)
#define NAND_256M                       (0x3 << 21)     /* and more */
#define NAND_128M                       (0x2 << 21)
#define NAND_64M                        (0x1 << 21)
#define NAND_32M                        (0x0 << 21)
#define ATMEL_16M                       (0x3 << 21)     /* and more */
#define ATMEL_8M                        (0x2 << 21)
#define ATMEL_4M_2M                     (0x1 << 21)
#define ATMEL_1M                        (0x0 << 21)     /* and less */
#define STM_32M                         (1 << 22)       /* and more */
#define STM_16M                         (0 << 22)       /* and less */

#define FLASH_PARALLEL_HIGH_PIN_CNT     (1 << 20)       /* else low pin cnt */

struct gemini_flash {
        struct device *dev;
        struct pinctrl *p;
        struct pinctrl_state *enabled_state;
        struct pinctrl_state *disabled_state;
};

/* Static local state */
static struct gemini_flash *gf;

static void gemini_flash_enable_pins(void)
{
        int ret;

        if (IS_ERR(gf->enabled_state))
                return;
        ret = pinctrl_select_state(gf->p, gf->enabled_state);
        if (ret)
                dev_err(gf->dev, "failed to enable pins\n");
}

static void gemini_flash_disable_pins(void)
{
        int ret;

        if (IS_ERR(gf->disabled_state))
                return;
        ret = pinctrl_select_state(gf->p, gf->disabled_state);
        if (ret)
                dev_err(gf->dev, "failed to disable pins\n");
}

static map_word __xipram gemini_flash_map_read(struct map_info *map,
                                               unsigned long ofs)
{
        map_word ret;

        gemini_flash_enable_pins();
        ret = inline_map_read(map, ofs);
        gemini_flash_disable_pins();

        return ret;
}

static void __xipram gemini_flash_map_write(struct map_info *map,
                                            const map_word datum,
                                            unsigned long ofs)
{
        gemini_flash_enable_pins();
        inline_map_write(map, datum, ofs);
        gemini_flash_disable_pins();
}

static void __xipram gemini_flash_map_copy_from(struct map_info *map,
                                                void *to, unsigned long from,
                                                ssize_t len)
{
        gemini_flash_enable_pins();
        inline_map_copy_from(map, to, from, len);
        gemini_flash_disable_pins();
}

static void __xipram gemini_flash_map_copy_to(struct map_info *map,
                                              unsigned long to,
                                              const void *from, ssize_t len)
{
        gemini_flash_enable_pins();
        inline_map_copy_to(map, to, from, len);
        gemini_flash_disable_pins();
}

int of_flash_probe_gemini(struct platform_device *pdev,
                          struct device_node *np,
                          struct map_info *map)
{
        struct regmap *rmap;
        struct device *dev = &pdev->dev;
        u32 val;
        int ret;

        /* Multiplatform guard */
        if (!of_device_is_compatible(np, "cortina,gemini-flash"))
                return 0;

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

        rmap = syscon_regmap_lookup_by_phandle(np, "syscon");
        if (IS_ERR(rmap)) {
                dev_err(dev, "no syscon\n");
                return PTR_ERR(rmap);
        }

        ret = regmap_read(rmap, GLOBAL_STATUS, &val);
        if (ret) {
                dev_err(dev, "failed to read global status register\n");
                return -ENODEV;
        }
        dev_dbg(dev, "global status reg: %08x\n", val);

        /*
         * It would be contradictory if a physmap flash was NOT parallel.
         */
        if ((val & FLASH_TYPE_MASK) != FLASH_TYPE_PARALLEL) {
                dev_err(dev, "flash is not parallel\n");
                return -ENODEV;
        }

        /*
         * Complain if DT data and hardware definition is different.
         */
        if (val & FLASH_WIDTH_16BIT) {
                if (map->bankwidth != 2)
                        dev_warn(dev, "flash hardware say flash is 16 bit wide but DT says it is %d bits wide\n",
                                 map->bankwidth * 8);
        } else {
                if (map->bankwidth != 1)
                        dev_warn(dev, "flash hardware say flash is 8 bit wide but DT says it is %d bits wide\n",
                                 map->bankwidth * 8);
        }

        gf->p = devm_pinctrl_get(dev);
        if (IS_ERR(gf->p)) {
                dev_err(dev, "no pinctrl handle\n");
                ret = PTR_ERR(gf->p);
                return ret;
        }

        gf->enabled_state = pinctrl_lookup_state(gf->p, "enabled");
        if (IS_ERR(gf->enabled_state))
                dev_err(dev, "no enabled pin control state\n");

        gf->disabled_state = pinctrl_lookup_state(gf->p, "disabled");
        if (IS_ERR(gf->enabled_state)) {
                dev_err(dev, "no disabled pin control state\n");
        } else {
                ret = pinctrl_select_state(gf->p, gf->disabled_state);
                if (ret)
                        dev_err(gf->dev, "failed to disable pins\n");
        }

        map->read = gemini_flash_map_read;
        map->write = gemini_flash_map_write;
        map->copy_from = gemini_flash_map_copy_from;
        map->copy_to = gemini_flash_map_copy_to;

        dev_info(dev, "initialized Gemini-specific physmap control\n");

        return 0;
}