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/*

 * MTD Oops/Panic logger

 *

 * Copyright (C) 2007 Nokia Corporation. All rights reserved.

 *

 * Author: Richard Purdie <rpurdie@openedhand.com>

 *

 * 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.

 *

 * 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 St, Fifth Floor, Boston, MA

 * 02110-1301 USA

 *

 */

#include <linux/kernel.h>

#include <linux/module.h>

#include <linux/console.h>

#include <linux/vmalloc.h>

#include <linux/workqueue.h>

#include <linux/sched.h>

#include <linux/wait.h>

#include <linux/mtd/mtd.h>

#define OOPS_PAGE_SIZE 4096

static struct mtdoops_context {

        int mtd_index;

        struct work_struct work;

        struct mtd_info *mtd;

        int oops_pages;

        int nextpage;

        int nextcount;

        void *oops_buf;

        int ready;

        int writecount;

} oops_cxt;

static void mtdoops_erase_callback(struct erase_info *done)

{

        wait_queue_head_t *wait_q = (wait_queue_head_t *)done->priv;

        wake_up(wait_q);

}

static int mtdoops_erase_block(struct mtd_info *mtd, int offset)

{

        struct erase_info erase;

        DECLARE_WAITQUEUE(wait, current);

        wait_queue_head_t wait_q;

        int ret;

        init_waitqueue_head(&wait_q);

        erase.mtd = mtd;

        erase.callback = mtdoops_erase_callback;

        erase.addr = offset;

        if (mtd->erasesize < OOPS_PAGE_SIZE)

                erase.len = OOPS_PAGE_SIZE;

        else

                erase.len = mtd->erasesize;

        erase.priv = (u_long)&wait_q;

        set_current_state(TASK_INTERRUPTIBLE);

        add_wait_queue(&wait_q, &wait);

        ret = mtd->erase(mtd, &erase);

        if (ret) {

                set_current_state(TASK_RUNNING);

                remove_wait_queue(&wait_q, &wait);

                printk (KERN_WARNING "mtdoops: erase of region [0x%x, 0x%x] "

                                     "on \"%s\" failed\n",

                        erase.addr, erase.len, mtd->name);

                return ret;

        }

        schedule();  /* Wait for erase to finish. */

        remove_wait_queue(&wait_q, &wait);

        return 0;

}

static int mtdoops_inc_counter(struct mtdoops_context *cxt)

{

        struct mtd_info *mtd = cxt->mtd;

        size_t retlen;

        u32 count;

        int ret;

        cxt->nextpage++;

        if (cxt->nextpage > cxt->oops_pages)

                cxt->nextpage = 0;

        cxt->nextcount++;

        if (cxt->nextcount == 0xffffffff)

                cxt->nextcount = 0;

        ret = mtd->read(mtd, cxt->nextpage * OOPS_PAGE_SIZE, 4,

                        &retlen, (u_char *) &count);

        if ((retlen != 4) || (ret < 0)) {

                printk(KERN_ERR "mtdoops: Read failure at %d (%td of 4 read)"

                                ", err %d.\n", cxt->nextpage * OOPS_PAGE_SIZE,

                                retlen, ret);

                return 1;

        }

        /* See if we need to erase the next block */

        if (count != 0xffffffff)

                return 1;

        printk(KERN_DEBUG "mtdoops: Ready %d, %d (no erase)\n",

                        cxt->nextpage, cxt->nextcount);

        cxt->ready = 1;

        return 0;

}

static void mtdoops_prepare(struct mtdoops_context *cxt)

{

        struct mtd_info *mtd = cxt->mtd;

        int i = 0, j, ret, mod;

        /* We were unregistered */

        if (!mtd)

                return;

        mod = (cxt->nextpage * OOPS_PAGE_SIZE) % mtd->erasesize;

        if (mod != 0) {

                cxt->nextpage = cxt->nextpage + ((mtd->erasesize - mod) / OOPS_PAGE_SIZE);

                if (cxt->nextpage > cxt->oops_pages)

                        cxt->nextpage = 0;

        }

        while (mtd->block_isbad &&

                        mtd->block_isbad(mtd, cxt->nextpage * OOPS_PAGE_SIZE)) {

badblock:

                printk(KERN_WARNING "mtdoops: Bad block at %08x\n",

                                cxt->nextpage * OOPS_PAGE_SIZE);

                i++;

                cxt->nextpage = cxt->nextpage + (mtd->erasesize / OOPS_PAGE_SIZE);

                if (cxt->nextpage > cxt->oops_pages)

                        cxt->nextpage = 0;

                if (i == (cxt->oops_pages / (mtd->erasesize / OOPS_PAGE_SIZE))) {

                        printk(KERN_ERR "mtdoops: All blocks bad!\n");

                        return;

                }

        }

        for (j = 0, ret = -1; (j < 3) && (ret < 0); j++)

                ret = mtdoops_erase_block(mtd, cxt->nextpage * OOPS_PAGE_SIZE);

        if (ret < 0) {

                if (mtd->block_markbad)

                        mtd->block_markbad(mtd, cxt->nextpage * OOPS_PAGE_SIZE);

                goto badblock;

        }

        printk(KERN_DEBUG "mtdoops: Ready %d, %d \n", cxt->nextpage, cxt->nextcount);

        cxt->ready = 1;

}

static void mtdoops_workfunc(struct work_struct *work)

{

        struct mtdoops_context *cxt =

                        container_of(work, struct mtdoops_context, work);

        mtdoops_prepare(cxt);

}

static int find_next_position(struct mtdoops_context *cxt)

{

        struct mtd_info *mtd = cxt->mtd;

        int page, maxpos = 0;

        u32 count, maxcount = 0xffffffff;

        size_t retlen;

        for (page = 0; page < cxt->oops_pages; page++) {

                mtd->read(mtd, page * OOPS_PAGE_SIZE, 4, &retlen, (u_char *) &count);

                if (count == 0xffffffff)

                        continue;

                if (maxcount == 0xffffffff) {

                        maxcount = count;

                        maxpos = page;

                } else if ((count < 0x40000000) && (maxcount > 0xc0000000)) {

                        maxcount = count;

                        maxpos = page;

                } else if ((count > maxcount) && (count < 0xc0000000)) {

                        maxcount = count;

                        maxpos = page;

                } else if ((count > maxcount) && (count > 0xc0000000)

                                        && (maxcount > 0x80000000)) {

                        maxcount = count;

                        maxpos = page;

                }

        }

        if (maxcount == 0xffffffff) {

                cxt->nextpage = 0;

                cxt->nextcount = 1;

                cxt->ready = 1;

                printk(KERN_DEBUG "mtdoops: Ready %d, %d (first init)\n",

                                cxt->nextpage, cxt->nextcount);

                return 0;

        }

        cxt->nextpage = maxpos;

        cxt->nextcount = maxcount;

        return mtdoops_inc_counter(cxt);

}

static void mtdoops_notify_add(struct mtd_info *mtd)

{

        struct mtdoops_context *cxt = &oops_cxt;

        int ret;

        if ((mtd->index != cxt->mtd_index) || cxt->mtd_index < 0)

                return;

        if (mtd->size < (mtd->erasesize * 2)) {

                printk(KERN_ERR "MTD partition %d not big enough for mtdoops\n",

                                mtd->index);

                return;

        }

        cxt->mtd = mtd;

        cxt->oops_pages = mtd->size / OOPS_PAGE_SIZE;

        ret = find_next_position(cxt);

        if (ret == 1)

                mtdoops_prepare(cxt);

        printk(KERN_DEBUG "mtdoops: Attached to MTD device %d\n", mtd->index);

}

static void mtdoops_notify_remove(struct mtd_info *mtd)

{

        struct mtdoops_context *cxt = &oops_cxt;

        if ((mtd->index != cxt->mtd_index) || cxt->mtd_index < 0)

                return;

        cxt->mtd = NULL;

        flush_scheduled_work();

}

static void mtdoops_console_sync(void)

{

        struct mtdoops_context *cxt = &oops_cxt;

        struct mtd_info *mtd = cxt->mtd;

        size_t retlen;

        int ret;

        if (!cxt->ready || !mtd)

                return;

        if (cxt->writecount == 0)

                return;

        if (cxt->writecount < OOPS_PAGE_SIZE)

                memset(cxt->oops_buf + cxt->writecount, 0xff,

                                        OOPS_PAGE_SIZE - cxt->writecount);

        ret = mtd->write(mtd, cxt->nextpage * OOPS_PAGE_SIZE,

                                        OOPS_PAGE_SIZE, &retlen, cxt->oops_buf);

        cxt->ready = 0;

        cxt->writecount = 0;

        if ((retlen != OOPS_PAGE_SIZE) || (ret < 0))

                printk(KERN_ERR "mtdoops: Write failure at %d (%td of %d written), err %d.\n",

                        cxt->nextpage * OOPS_PAGE_SIZE, retlen, OOPS_PAGE_SIZE, ret);

        ret = mtdoops_inc_counter(cxt);

        if (ret == 1)

                schedule_work(&cxt->work);

}

static void

mtdoops_console_write(struct console *co, const char *s, unsigned int count)

{

        struct mtdoops_context *cxt = co->data;

        struct mtd_info *mtd = cxt->mtd;

        int i;

        if (!oops_in_progress) {

                mtdoops_console_sync();

                return;

        }

        if (!cxt->ready || !mtd)

                return;

        if (cxt->writecount == 0) {

                u32 *stamp = cxt->oops_buf;

                *stamp = cxt->nextcount;

                cxt->writecount = 4;

        }

        if ((count + cxt->writecount) > OOPS_PAGE_SIZE)

                count = OOPS_PAGE_SIZE - cxt->writecount;

        for (i = 0; i < count; i++, s++)

                *((char *)(cxt->oops_buf) + cxt->writecount + i) = *s;

        cxt->writecount = cxt->writecount + count;

}

static int __init mtdoops_console_setup(struct console *co, char *options)

{

        struct mtdoops_context *cxt = co->data;

        if (cxt->mtd_index != -1)

                return -EBUSY;

        if (co->index == -1)

                return -EINVAL;

        cxt->mtd_index = co->index;

        return 0;

}

static struct mtd_notifier mtdoops_notifier = {

        .add    = mtdoops_notify_add,

        .remove = mtdoops_notify_remove,

};

static struct console mtdoops_console = {

        .name           = "ttyMTD",

        .write          = mtdoops_console_write,

        .setup          = mtdoops_console_setup,

        .unblank        = mtdoops_console_sync,

        .flags          = CON_PRINTBUFFER,

        .index          = -1,

        .data           = &oops_cxt,

};

static int __init mtdoops_console_init(void)

{

        struct mtdoops_context *cxt = &oops_cxt;

        cxt->mtd_index = -1;

        cxt->oops_buf = vmalloc(OOPS_PAGE_SIZE);

        if (!cxt->oops_buf) {

                printk(KERN_ERR "Failed to allocate oops buffer workspace\n");

                return -ENOMEM;

        }

        INIT_WORK(&cxt->work, mtdoops_workfunc);

        register_console(&mtdoops_console);

        register_mtd_user(&mtdoops_notifier);

        return 0;

}

static void __exit mtdoops_console_exit(void)

{

        struct mtdoops_context *cxt = &oops_cxt;

        unregister_mtd_user(&mtdoops_notifier);

        unregister_console(&mtdoops_console);

        vfree(cxt->oops_buf);

}

subsys_initcall(mtdoops_console_init);

module_exit(mtdoops_console_exit);

MODULE_LICENSE("GPL");

MODULE_AUTHOR("Richard Purdie <rpurdie@openedhand.com>");

MODULE_DESCRIPTION("MTD Oops/Panic console logger/driver");