/*
 * LPDDR flash memory device operations. This module provides read, write,
 * erase, lock/unlock support for LPDDR flash memories
 * (C) 2008 Korolev Alexey <akorolev@infradead.org>
 * (C) 2008 Vasiliy Leonenko <vasiliy.leonenko@gmail.com>
 * Many thanks to Roman Borisov for initial enabling
 *
 * 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.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
 * 02110-1301, USA.
 * TODO:
 * Implement VPP management
 * Implement XIP support
 * Implement OTP support
 */
#include <linux/mtd/pfow.h>
#include <linux/mtd/qinfo.h>
#include <linux/slab.h>
#include <linux/module.h>

static int lpddr_read(struct mtd_info *mtd, loff_t adr, size_t len,
                                        size_t *retlen, u_char *buf);
static int lpddr_write_buffers(struct mtd_info *mtd, loff_t to,
                                size_t len, size_t *retlen, const u_char *buf);
static int lpddr_writev(struct mtd_info *mtd, const struct kvec *vecs,
                                unsigned long count, loff_t to, size_t *retlen);
static int lpddr_erase(struct mtd_info *mtd, struct erase_info *instr);
static int lpddr_lock(struct mtd_info *mtd, loff_t ofs, uint64_t len);
static int lpddr_unlock(struct mtd_info *mtd, loff_t ofs, uint64_t len);
static int lpddr_point(struct mtd_info *mtd, loff_t adr, size_t len,
                        size_t *retlen, void **mtdbuf, resource_size_t *phys);
static int lpddr_unpoint(struct mtd_info *mtd, loff_t adr, size_t len);
static int get_chip(struct map_info *map, struct flchip *chip, int mode);
static int chip_ready(struct map_info *map, struct flchip *chip, int mode);
static void put_chip(struct map_info *map, struct flchip *chip);

struct mtd_info *lpddr_cmdset(struct map_info *map)
{
        struct lpddr_private *lpddr = map->fldrv_priv;
        struct flchip_shared *shared;
        struct flchip *chip;
        struct mtd_info *mtd;
        int numchips;
        int i, j;

        mtd = kzalloc(sizeof(*mtd), GFP_KERNEL);
        if (!mtd)
                return NULL;
        mtd->priv = map;
        mtd->type = MTD_NORFLASH;

        /* Fill in the default mtd operations */
        mtd->_read = lpddr_read;
        mtd->type = MTD_NORFLASH;
        mtd->flags = MTD_CAP_NORFLASH;
        mtd->flags &= ~MTD_BIT_WRITEABLE;
        mtd->_erase = lpddr_erase;
        mtd->_write = lpddr_write_buffers;
        mtd->_writev = lpddr_writev;
        mtd->_lock = lpddr_lock;
        mtd->_unlock = lpddr_unlock;
        if (map_is_linear(map)) {
                mtd->_point = lpddr_point;
                mtd->_unpoint = lpddr_unpoint;
        }
        mtd->size = 1 << lpddr->qinfo->DevSizeShift;
        mtd->erasesize = 1 << lpddr->qinfo->UniformBlockSizeShift;
        mtd->writesize = 1 << lpddr->qinfo->BufSizeShift;

        shared = kmalloc(sizeof(struct flchip_shared) * lpddr->numchips,
                                                GFP_KERNEL);
        if (!shared) {
                kfree(lpddr);
                kfree(mtd);
                return NULL;
        }

        chip = &lpddr->chips[0];
        numchips = lpddr->numchips / lpddr->qinfo->HWPartsNum;
        for (i = 0; i < numchips; i++) {
                shared[i].writing = shared[i].erasing = NULL;
                mutex_init(&shared[i].lock);
                for (j = 0; j < lpddr->qinfo->HWPartsNum; j++) {
                        *chip = lpddr->chips[i];
                        chip->start += j << lpddr->chipshift;
                        chip->oldstate = chip->state = FL_READY;
                        chip->priv = &shared[i];
                        /* those should be reset too since
                           they create memory references. */
                        init_waitqueue_head(&chip->wq);
                        mutex_init(&chip->mutex);
                        chip++;
                }
        }

        return mtd;
}
EXPORT_SYMBOL(lpddr_cmdset);

static int wait_for_ready(struct map_info *map, struct flchip *chip,
                unsigned int chip_op_time)
{
        unsigned int timeo, reset_timeo, sleep_time;
        unsigned int dsr;
        flstate_t chip_state = chip->state;
        int ret = 0;

        /* set our timeout to 8 times the expected delay */
        timeo = chip_op_time * 8;
        if (!timeo)
                timeo = 500000;
        reset_timeo = timeo;
        sleep_time = chip_op_time / 2;

        for (;;) {
                dsr = CMDVAL(map_read(map, map->pfow_base + PFOW_DSR));
                if (dsr & DSR_READY_STATUS)
                        break;
                if (!timeo) {
                        printk(KERN_ERR "%s: Flash timeout error state %d \n",
                                                        map->name, chip_state);
                        ret = -ETIME;
                        break;
                }

                /* OK Still waiting. Drop the lock, wait a while and retry. */
                mutex_unlock(&chip->mutex);
                if (sleep_time >= 1000000/HZ) {
                        /*
                         * Half of the normal delay still remaining
                         * can be performed with a sleeping delay instead
                         * of busy waiting.
                         */
                        msleep(sleep_time/1000);
                        timeo -= sleep_time;
                        sleep_time = 1000000/HZ;
                } else {
                        udelay(1);
                        cond_resched();
                        timeo--;
                }
                mutex_lock(&chip->mutex);

                while (chip->state != chip_state) {
                        /* Someone's suspended the operation: sleep */
                        DECLARE_WAITQUEUE(wait, current);
                        set_current_state(TASK_UNINTERRUPTIBLE);
                        add_wait_queue(&chip->wq, &wait);
                        mutex_unlock(&chip->mutex);
                        schedule();
                        remove_wait_queue(&chip->wq, &wait);
                        mutex_lock(&chip->mutex);
                }
                if (chip->erase_suspended || chip->write_suspended)  {
                        /* Suspend has occurred while sleep: reset timeout */
                        timeo = reset_timeo;
                        chip->erase_suspended = chip->write_suspended = 0;
                }
        }
        /* check status for errors */
        if (dsr & DSR_ERR) {
                /* Clear DSR*/
                map_write(map, CMD(~(DSR_ERR)), map->pfow_base + PFOW_DSR);
                printk(KERN_WARNING"%s: Bad status on wait: 0x%x \n",
                                map->name, dsr);
                print_drs_error(dsr);
                ret = -EIO;
        }
        chip->state = FL_READY;
        return ret;
}

static int get_chip(struct map_info *map, struct flchip *chip, int mode)
{
        int ret;
        DECLARE_WAITQUEUE(wait, current);

 retry:
        if (chip->priv && (mode == FL_WRITING || mode == FL_ERASING)
                && chip->state != FL_SYNCING) {
                /*
                 * OK. We have possibility for contension on the write/erase
                 * operations which are global to the real chip and not per
                 * partition.  So let's fight it over in the partition which
                 * currently has authority on the operation.
                 *
                 * The rules are as follows:
                 *
                 * - any write operation must own shared->writing.
                 *
                 * - any erase operation must own _both_ shared->writing and
                 *   shared->erasing.
                 *
                 * - contension arbitration is handled in the owner's context.
                 *
                 * The 'shared' struct can be read and/or written only when
                 * its lock is taken.
                 */
                struct flchip_shared *shared = chip->priv;
                struct flchip *contender;
                mutex_lock(&shared->lock);
                contender = shared->writing;
                if (contender && contender != chip) {
                        /*
                         * The engine to perform desired operation on this
                         * partition is already in use by someone else.
                         * Let's fight over it in the context of the chip
                         * currently using it.  If it is possible to suspend,
                         * that other partition will do just that, otherwise
                         * it'll happily send us to sleep.  In any case, when
                         * get_chip returns success we're clear to go ahead.
                         */
                        ret = mutex_trylock(&contender->mutex);
                        mutex_unlock(&shared->lock);
                        if (!ret)
                                goto retry;
                        mutex_unlock(&chip->mutex);
                        ret = chip_ready(map, contender, mode);
                        mutex_lock(&chip->mutex);

                        if (ret == -EAGAIN) {
                                mutex_unlock(&contender->mutex);
                                goto retry;
                        }
                        if (ret) {
                                mutex_unlock(&contender->mutex);
                                return ret;
                        }
                        mutex_lock(&shared->lock);

                        /* We should not own chip if it is already in FL_SYNCING
                         * state. Put contender and retry. */
                        if (chip->state == FL_SYNCING) {
                                put_chip(map, contender);
                                mutex_unlock(&contender->mutex);
                                goto retry;
                        }
                        mutex_unlock(&contender->mutex);
                }

                /* Check if we have suspended erase on this chip.
                   Must sleep in such a case. */
                if (mode == FL_ERASING && shared->erasing
                    && shared->erasing->oldstate == FL_ERASING) {
                        mutex_unlock(&shared->lock);
                        set_current_state(TASK_UNINTERRUPTIBLE);
                        add_wait_queue(&chip->wq, &wait);
                        mutex_unlock(&chip->mutex);
                        schedule();
                        remove_wait_queue(&chip->wq, &wait);
                        mutex_lock(&chip->mutex);
                        goto retry;
                }

                /* We now own it */
                shared->writing = chip;
                if (mode == FL_ERASING)
                        shared->erasing = chip;
                mutex_unlock(&shared->lock);
        }

        ret = chip_ready(map, chip, mode);
        if (ret == -EAGAIN)
                goto retry;

        return ret;
}

static int chip_ready(struct map_info *map, struct flchip *chip, int mode)
{
        struct lpddr_private *lpddr = map->fldrv_priv;
        int ret = 0;
        DECLARE_WAITQUEUE(wait, current);

        /* Prevent setting state FL_SYNCING for chip in suspended state. */
        if (FL_SYNCING == mode && FL_READY != chip->oldstate)
                goto sleep;

        switch (chip->state) {
        case FL_READY:
        case FL_JEDEC_QUERY:
                return 0;

        case FL_ERASING:
                if (!lpddr->qinfo->SuspEraseSupp ||
                        !(mode == FL_READY || mode == FL_POINT))
                        goto sleep;

                map_write(map, CMD(LPDDR_SUSPEND),
                        map->pfow_base + PFOW_PROGRAM_ERASE_SUSPEND);
                chip->oldstate = FL_ERASING;
                chip->state = FL_ERASE_SUSPENDING;
                ret = wait_for_ready(map, chip, 0);
                if (ret) {
                        /* Oops. something got wrong. */
                        /* Resume and pretend we weren't here.  */
                        put_chip(map, chip);
                        printk(KERN_ERR "%s: suspend operation failed."
                                        "State may be wrong \n", map->name);
                        return -EIO;
                }
                chip->erase_suspended = 1;
                chip->state = FL_READY;
                return 0;
                /* Erase suspend */
        case FL_POINT:
                /* Only if there's no operation suspended... */
                if (mode == FL_READY && chip->oldstate == FL_READY)
                        return 0;

        default:
sleep:
                set_current_state(TASK_UNINTERRUPTIBLE);
                add_wait_queue(&chip->wq, &wait);
                mutex_unlock(&chip->mutex);
                schedule();
                remove_wait_queue(&chip->wq, &wait);
                mutex_lock(&chip->mutex);
                return -EAGAIN;
        }
}

static void put_chip(struct map_info *map, struct flchip *chip)
{
        if (chip->priv) {
                struct flchip_shared *shared = chip->priv;
                mutex_lock(&shared->lock);
                if (shared->writing == chip && chip->oldstate == FL_READY) {
                        /* We own the ability to write, but we're done */
                        shared->writing = shared->erasing;
                        if (shared->writing && shared->writing != chip) {
                                /* give back the ownership */
                                struct flchip *loaner = shared->writing;
                                mutex_lock(&loaner->mutex);
                                mutex_unlock(&shared->lock);
                                mutex_unlock(&chip->mutex);
                                put_chip(map, loaner);
                                mutex_lock(&chip->mutex);
                                mutex_unlock(&loaner->mutex);
                                wake_up(&chip->wq);
                                return;
                        }
                        shared->erasing = NULL;
                        shared->writing = NULL;
                } else if (shared->erasing == chip && shared->writing != chip) {
                        /*
                         * We own the ability to erase without the ability
                         * to write, which means the erase was suspended
                         * and some other partition is currently writing.
                         * Don't let the switch below mess things up since
                         * we don't have ownership to resume anything.
                         */
                        mutex_unlock(&shared->lock);
                        wake_up(&chip->wq);
                        return;
                }
                mutex_unlock(&shared->lock);
        }

        switch (chip->oldstate) {
        case FL_ERASING:
                map_write(map, CMD(LPDDR_RESUME),
                                map->pfow_base + PFOW_COMMAND_CODE);
                map_write(map, CMD(LPDDR_START_EXECUTION),
                                map->pfow_base + PFOW_COMMAND_EXECUTE);
                chip->oldstate = FL_READY;
                chip->state = FL_ERASING;
                break;
        case FL_READY:
                break;
        default:
                printk(KERN_ERR "%s: put_chip() called with oldstate %d!\n",
                                map->name, chip->oldstate);
        }
        wake_up(&chip->wq);
}

static int do_write_buffer(struct map_info *map, struct flchip *chip,
                        unsigned long adr, const struct kvec **pvec,
                        unsigned long *pvec_seek, int len)
{
        struct lpddr_private *lpddr = map->fldrv_priv;
        map_word datum;
        int ret, wbufsize, word_gap, words;
        const struct kvec *vec;
        unsigned long vec_seek;
        unsigned long prog_buf_ofs;

        wbufsize = 1 << lpddr->qinfo->BufSizeShift;

        mutex_lock(&chip->mutex);
        ret = get_chip(map, chip, FL_WRITING);
        if (ret) {
                mutex_unlock(&chip->mutex);
                return ret;
        }
        /* Figure out the number of words to write */
        word_gap = (-adr & (map_bankwidth(map)-1));
        words = (len - word_gap + map_bankwidth(map) - 1) / map_bankwidth(map);
        if (!word_gap) {
                words--;
        } else {
                word_gap = map_bankwidth(map) - word_gap;
                adr -= word_gap;
                datum = map_word_ff(map);
        }
        /* Write data */
        /* Get the program buffer offset from PFOW register data first*/
        prog_buf_ofs = map->pfow_base + CMDVAL(map_read(map,
                                map->pfow_base + PFOW_PROGRAM_BUFFER_OFFSET));
        vec = *pvec;
        vec_seek = *pvec_seek;
        do {
                int n = map_bankwidth(map) - word_gap;

                if (n > vec->iov_len - vec_seek)
                        n = vec->iov_len - vec_seek;
                if (n > len)
                        n = len;

                if (!word_gap && (len < map_bankwidth(map)))
                        datum = map_word_ff(map);

                datum = map_word_load_partial(map, datum,
                                vec->iov_base + vec_seek, word_gap, n);

                len -= n;
                word_gap += n;
                if (!len || word_gap == map_bankwidth(map)) {
                        map_write(map, datum, prog_buf_ofs);
                        prog_buf_ofs += map_bankwidth(map);
                        word_gap = 0;
                }

                vec_seek += n;
                if (vec_seek == vec->iov_len) {
                        vec++;
                        vec_seek = 0;
                }
        } while (len);
        *pvec = vec;
        *pvec_seek = vec_seek;

        /* GO GO GO */
        send_pfow_command(map, LPDDR_BUFF_PROGRAM, adr, wbufsize, NULL);
        chip->state = FL_WRITING;
        ret = wait_for_ready(map, chip, (1<<lpddr->qinfo->ProgBufferTime));
        if (ret)        {
                printk(KERN_WARNING"%s Buffer program error: %d at %lx; \n",
                        map->name, ret, adr);
                goto out;
        }

 out:   put_chip(map, chip);
        mutex_unlock(&chip->mutex);
        return ret;
}

static int do_erase_oneblock(struct mtd_info *mtd, loff_t adr)
{
        struct map_info *map = mtd->priv;
        struct lpddr_private *lpddr = map->fldrv_priv;
        int chipnum = adr >> lpddr->chipshift;
        struct flchip *chip = &lpddr->chips[chipnum];
        int ret;

        mutex_lock(&chip->mutex);
        ret = get_chip(map, chip, FL_ERASING);
        if (ret) {
                mutex_unlock(&chip->mutex);
                return ret;
        }
        send_pfow_command(map, LPDDR_BLOCK_ERASE, adr, 0, NULL);
        chip->state = FL_ERASING;
        ret = wait_for_ready(map, chip, (1<<lpddr->qinfo->BlockEraseTime)*1000);
        if (ret) {
                printk(KERN_WARNING"%s Erase block error %d at : %llx\n",
                        map->name, ret, adr);
                goto out;
        }
 out:   put_chip(map, chip);
        mutex_unlock(&chip->mutex);
        return ret;
}

static int lpddr_read(struct mtd_info *mtd, loff_t adr, size_t len,
                        size_t *retlen, u_char *buf)
{
        struct map_info *map = mtd->priv;
        struct lpddr_private *lpddr = map->fldrv_priv;
        int chipnum = adr >> lpddr->chipshift;
        struct flchip *chip = &lpddr->chips[chipnum];
        int ret = 0;

        mutex_lock(&chip->mutex);
        ret = get_chip(map, chip, FL_READY);
        if (ret) {
                mutex_unlock(&chip->mutex);
                return ret;
        }

        map_copy_from(map, buf, adr, len);
        *retlen = len;

        put_chip(map, chip);
        mutex_unlock(&chip->mutex);
        return ret;
}

static int lpddr_point(struct mtd_info *mtd, loff_t adr, size_t len,
                        size_t *retlen, void **mtdbuf, resource_size_t *phys)
{
        struct map_info *map = mtd->priv;
        struct lpddr_private *lpddr = map->fldrv_priv;
        int chipnum = adr >> lpddr->chipshift;
        unsigned long ofs, last_end = 0;
        struct flchip *chip = &lpddr->chips[chipnum];
        int ret = 0;

        if (!map->virt)
                return -EINVAL;

        /* ofs: offset within the first chip that the first read should start */
        ofs = adr - (chipnum << lpddr->chipshift);
        *mtdbuf = (void *)map->virt + chip->start + ofs;

        while (len) {
                unsigned long thislen;

                if (chipnum >= lpddr->numchips)
                        break;

                /* We cannot point across chips that are virtually disjoint */
                if (!last_end)
                        last_end = chip->start;
                else if (chip->start != last_end)
                        break;

                if ((len + ofs - 1) >> lpddr->chipshift)
                        thislen = (1<<lpddr->chipshift) - ofs;
                else
                        thislen = len;
                /* get the chip */
                mutex_lock(&chip->mutex);
                ret = get_chip(map, chip, FL_POINT);
                mutex_unlock(&chip->mutex);
                if (ret)
                        break;

                chip->state = FL_POINT;
                chip->ref_point_counter++;
                *retlen += thislen;
                len -= thislen;

                ofs = 0;
                last_end += 1 << lpddr->chipshift;
                chipnum++;
                chip = &lpddr->chips[chipnum];
        }
        return 0;
}

static int lpddr_unpoint (struct mtd_info *mtd, loff_t adr, size_t len)
{
        struct map_info *map = mtd->priv;
        struct lpddr_private *lpddr = map->fldrv_priv;
        int chipnum = adr >> lpddr->chipshift, err = 0;
        unsigned long ofs;

        /* ofs: offset within the first chip that the first read should start */
        ofs = adr - (chipnum << lpddr->chipshift);

        while (len) {
                unsigned long thislen;
                struct flchip *chip;

                chip = &lpddr->chips[chipnum];
                if (chipnum >= lpddr->numchips)
                        break;

                if ((len + ofs - 1) >> lpddr->chipshift)
                        thislen = (1<<lpddr->chipshift) - ofs;
                else
                        thislen = len;

                mutex_lock(&chip->mutex);
                if (chip->state == FL_POINT) {
                        chip->ref_point_counter--;
                        if (chip->ref_point_counter == 0)
                                chip->state = FL_READY;
                } else {
                        printk(KERN_WARNING "%s: Warning: unpoint called on non"
                                        "pointed region\n", map->name);
                        err = -EINVAL;
                }

                put_chip(map, chip);
                mutex_unlock(&chip->mutex);

                len -= thislen;
                ofs = 0;
                chipnum++;
        }

        return err;
}

static int lpddr_write_buffers(struct mtd_info *mtd, loff_t to, size_t len,
                                size_t *retlen, const u_char *buf)
{
        struct kvec vec;

        vec.iov_base = (void *) buf;
        vec.iov_len = len;

        return lpddr_writev(mtd, &vec, 1, to, retlen);
}


static int lpddr_writev(struct mtd_info *mtd, const struct kvec *vecs,
                                unsigned long count, loff_t to, size_t *retlen)
{
        struct map_info *map = mtd->priv;
        struct lpddr_private *lpddr = map->fldrv_priv;
        int ret = 0;
        int chipnum;
        unsigned long ofs, vec_seek, i;
        int wbufsize = 1 << lpddr->qinfo->BufSizeShift;
        size_t len = 0;

        for (i = 0; i < count; i++)
                len += vecs[i].iov_len;

        if (!len)
                return 0;

        chipnum = to >> lpddr->chipshift;

        ofs = to;
        vec_seek = 0;

        do {
                /* We must not cross write block boundaries */
                int size = wbufsize - (ofs & (wbufsize-1));

                if (size > len)
                        size = len;

                ret = do_write_buffer(map, &lpddr->chips[chipnum],
                                          ofs, &vecs, &vec_seek, size);
                if (ret)
                        return ret;

                ofs += size;
                (*retlen) += size;
                len -= size;

                /* Be nice and reschedule with the chip in a usable
                 * state for other processes */
                cond_resched();

        } while (len);

        return 0;
}

static int lpddr_erase(struct mtd_info *mtd, struct erase_info *instr)
{
        unsigned long ofs, len;
        int ret;
        struct map_info *map = mtd->priv;
        struct lpddr_private *lpddr = map->fldrv_priv;
        int size = 1 << lpddr->qinfo->UniformBlockSizeShift;

        ofs = instr->addr;
        len = instr->len;

        while (len > 0) {
                ret = do_erase_oneblock(mtd, ofs);
                if (ret)
                        return ret;
                ofs += size;
                len -= size;
        }

        return 0;
}

#define DO_XXLOCK_LOCK          1
#define DO_XXLOCK_UNLOCK        2
static int do_xxlock(struct mtd_info *mtd, loff_t adr, uint32_t len, int thunk)
{
        int ret = 0;
        struct map_info *map = mtd->priv;
        struct lpddr_private *lpddr = map->fldrv_priv;
        int chipnum = adr >> lpddr->chipshift;
        struct flchip *chip = &lpddr->chips[chipnum];

        mutex_lock(&chip->mutex);
        ret = get_chip(map, chip, FL_LOCKING);
        if (ret) {
                mutex_unlock(&chip->mutex);
                return ret;
        }

        if (thunk == DO_XXLOCK_LOCK) {
                send_pfow_command(map, LPDDR_LOCK_BLOCK, adr, adr + len, NULL);
                chip->state = FL_LOCKING;
        } else if (thunk == DO_XXLOCK_UNLOCK) {
                send_pfow_command(map, LPDDR_UNLOCK_BLOCK, adr, adr + len, NULL);
                chip->state = FL_UNLOCKING;
        } else
                BUG();

        ret = wait_for_ready(map, chip, 1);
        if (ret)        {
                printk(KERN_ERR "%s: block unlock error status %d \n",
                                map->name, ret);
                goto out;
        }
out:    put_chip(map, chip);
        mutex_unlock(&chip->mutex);
        return ret;
}

static int lpddr_lock(struct mtd_info *mtd, loff_t ofs, uint64_t len)
{
        return do_xxlock(mtd, ofs, len, DO_XXLOCK_LOCK);
}

static int lpddr_unlock(struct mtd_info *mtd, loff_t ofs, uint64_t len)
{
        return do_xxlock(mtd, ofs, len, DO_XXLOCK_UNLOCK);
}

MODULE_LICENSE("GPL");
MODULE_AUTHOR("Alexey Korolev <akorolev@infradead.org>");
MODULE_DESCRIPTION("MTD driver for LPDDR flash chips");