text: /****************************************************************************
   * drivers/mtd/rammtd.c
   *
   *   Copyright (C) 2011-2013 Gregory Nutt. All rights reserved.
   *   Author: Gregory Nutt <gnutt@nuttx.org>
   *
   * Redistribution and use in source and binary forms, with or without
   * modification, are permitted provided that the following conditions
   * are met:
   *
   * 1. Redistributions of source code must retain the above copyright
   *    notice, this list of conditions and the following disclaimer.
   * 2. Redistributions in binary form must reproduce the above copyright
   *    notice, this list of conditions and the following disclaimer in
   *    the documentation and/or other materials provided with the
   *    distribution.
   * 3. Neither the name NuttX nor the names of its contributors may be
   *    used to endorse or promote products derived from this software
   *    without specific prior written permission.
   *
   * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
   * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
   * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
   * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
   * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
   * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
   * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
   * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
   * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
   * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
   * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
   * POSSIBILITY OF SUCH DAMAGE.
   *
   ****************************************************************************/
  
  /****************************************************************************
   * Included Files
   ****************************************************************************/
  
  #include <nuttx/config.h>
  
  #include <sys/types.h>
  #include <stdint.h>
  #include <string.h>
  #include <assert.h>
  #include <errno.h>
  #include <debug.h>
  
  #include <nuttx/kmalloc.h>
  #include <nuttx/fs/ioctl.h>
  #include <nuttx/mtd/mtd.h>
  
  /****************************************************************************
   * Pre-processor Definitions
   ****************************************************************************/
  /* Configuration ************************************************************/
  
  #ifndef CONFIG_RAMMTD_BLOCKSIZE
  #  define CONFIG_RAMMTD_BLOCKSIZE 512
  #endif
  
  #ifndef CONFIG_RAMMTD_ERASESIZE
  #  define CONFIG_RAMMTD_ERASESIZE 4096
  #endif
  
  #ifndef CONFIG_RAMMTD_ERASESTATE
  #  define CONFIG_RAMMTD_ERASESTATE 0xff
  #endif
  
  #if CONFIG_RAMMTD_ERASESTATE != 0xff && CONFIG_RAMMTD_ERASESTATE != 0x00
  #  error "Unsupported value for CONFIG_RAMMTD_ERASESTATE"
  #endif
  
  #if CONFIG_RAMMTD_BLOCKSIZE > CONFIG_RAMMTD_ERASESIZE
  #  error "Must have CONFIG_RAMMTD_BLOCKSIZE <= CONFIG_RAMMTD_ERASESIZE"
  #endif
  
  #undef  RAMMTD_BLKPER
  #define RAMMTD_BLKPER (CONFIG_RAMMTD_ERASESIZE/CONFIG_RAMMTD_BLOCKSIZE)
  
  #if RAMMTD_BLKPER*CONFIG_RAMMTD_BLOCKSIZE != CONFIG_RAMMTD_ERASESIZE
  #  error "CONFIG_RAMMTD_ERASESIZE must be an even multiple of CONFIG_RAMMTD_BLOCKSIZE"
  #endif
  
  /****************************************************************************
   * Private Types
   ****************************************************************************/
  
  /* This type represents the state of the MTD device.  The struct mtd_dev_s
   * must appear at the beginning of the definition so that you can freely
   * cast between pointers to struct mtd_dev_s and struct ram_dev_s.
   */
  
  struct ram_dev_s
  {
    struct mtd_dev_s mtd;      /* MTD device */
    FAR uint8_t     *start;    /* Start of RAM */
    size_t           nblocks;  /* Number of erase blocks */
  };
  
  /****************************************************************************
   * Private Function Prototypes
   ****************************************************************************/
  
  /* The RAM MTD driver may be useful just as it is, but another good use of
   * the RAM MTD driver is as a FLASH simulation -- to support testing of FLASH
   * based logic without having FLASH.  CONFIG_RAMMTD_FLASHSIM will add some
   * extra logic to improve the level of FLASH simulation.
   */
  
  #define ram_read(dest, src, len) memcpy(dest, src, len)
  #ifdef CONFIG_RAMMTD_FLASHSIM
  static void *ram_write(FAR void *dest, FAR const void *src, size_t len);
  #else
  #  define ram_write(dest, src, len) memcpy(dest, src, len)
  #endif
  
  /* MTD driver methods */
  
  static int ram_erase(FAR struct mtd_dev_s *dev, off_t startblock, size_t nblocks);
  static ssize_t ram_bread(FAR struct mtd_dev_s *dev, off_t startblock, size_t nblocks,
                            FAR uint8_t *buf);
  static ssize_t ram_bwrite(FAR struct mtd_dev_s *dev, off_t startblock, size_t nblocks,
                             FAR const uint8_t *buf);
  static ssize_t ram_byteread(FAR struct mtd_dev_s *dev, off_t offset,
                              size_t nbytes, FAR uint8_t *buf);
  #ifdef CONFIG_MTD_BYTE_WRITE
  static ssize_t ram_bytewrite(FAR struct mtd_dev_s *dev, off_t offset,
                               size_t nbytes, FAR const uint8_t *buf);
  #endif
  static int ram_ioctl(FAR struct mtd_dev_s *dev, int cmd, unsigned long arg);
  
  /****************************************************************************
   * Private Functions
   ****************************************************************************/
  
  /****************************************************************************
   * Name: ram_write
   ****************************************************************************/
  
  #ifdef CONFIG_RAMMTD_FLASHSIM
  static void *ram_write(FAR void *dest, FAR const void *src, size_t len)
  {
    FAR uint8_t       *pout = (FAR uint8_t *)dest;
    FAR const uint8_t *pin  = (FAR const uint8_t *)src;
  
    while (len-- > 0)
      {
        /* Get the source and destination values */
  
        uint8_t oldvalue = *pout;
        uint8_t srcvalue = *pin++;
        uint8_t newvalue;
  
        /* Get the new destination value, accounting for bits that cannot be
         * changes because they are not in the erased state.
         */
  
  #if CONFIG_RAMMTD_ERASESTATE == 0xff
        newvalue = oldvalue & srcvalue; /* We can only clear bits */
  #else /* CONFIG_RAMMTD_ERASESTATE == 0x00 */
        newvalue = oldvalue | srcvalue; /* We can only set bits */
  #endif
  
        /* Report any attempt to change the value of bits that are not in the
         * erased state.
         */
  
  #ifdef CONFIG_DEBUG_FEATURES
        if (newvalue != srcvalue)
          {
            _err("ERROR: Bad write: source=%02x dest=%02x result=%02x\n",
                srcvalue, oldvalue, newvalue);
          }
  #endif
  
        /* Write the modified value to simulated FLASH */
  
        *pout++ = newvalue;
      }
  
    return dest;
  }
  #endif
  
  /****************************************************************************
   * Name: ram_erase
   ****************************************************************************/
  
  static int ram_erase(FAR struct mtd_dev_s *dev, off_t startblock,
                       size_t nblocks)
  {
    FAR struct ram_dev_s *priv = (FAR struct ram_dev_s *)dev;
    off_t offset;
    size_t nbytes;
  
    DEBUGASSERT(dev);
  
    /* Don't let the erase exceed the size of the ram buffer */
  
    if (startblock >= priv->nblocks)
      {
        return 0;
      }
  
    if (startblock + nblocks > priv->nblocks)
      {
        nblocks = priv->nblocks - startblock;
      }
  
    /* Convert the erase block to a logical block and the number of blocks
     * in logical block numbers
     */
  
    startblock *= RAMMTD_BLKPER;
    nblocks    *= RAMMTD_BLKPER;
  
    /* Get the offset corresponding to the first block and the size
     * corresponding to the number of blocks.
     */
  
    offset = startblock * CONFIG_RAMMTD_BLOCKSIZE;
    nbytes = nblocks * CONFIG_RAMMTD_BLOCKSIZE;
  
    /* Then erase the data in RAM */
  
    memset(&priv->start[offset], CONFIG_RAMMTD_ERASESTATE, nbytes);
    return OK;
  }
  
  /****************************************************************************
   * Name: ram_bread
   ****************************************************************************/
  
  static ssize_t ram_bread(FAR struct mtd_dev_s *dev, off_t startblock, size_t nblocks,
                            FAR uint8_t *buf)
  {
    FAR struct ram_dev_s *priv = (FAR struct ram_dev_s *)dev;
    off_t offset;
    off_t maxblock;
    size_t nbytes;
  
    DEBUGASSERT(dev && buf);
  
    /* Don't let the read exceed the size of the ram buffer */
  
    maxblock = priv->nblocks * RAMMTD_BLKPER;
    if (startblock >= maxblock)
      {
        return 0;
      }
  
    if (startblock + nblocks > maxblock)
      {
        nblocks = maxblock - startblock;
      }
  
    /* Get the offset corresponding to the first block and the size
     * corresponding to the number of blocks.
     */
  
    offset = startblock * CONFIG_RAMMTD_BLOCKSIZE;
    nbytes = nblocks * CONFIG_RAMMTD_BLOCKSIZE;
  
    /* Then read the data frp, RAM */
  
    ram_read(buf, &priv->start[offset], nbytes);
    return nblocks;
  }
  
  /****************************************************************************
   * Name: ram_bwrite
   ****************************************************************************/
  
  static ssize_t ram_bwrite(FAR struct mtd_dev_s *dev, off_t startblock,
                            size_t nblocks, FAR const uint8_t *buf)
  {
    FAR struct ram_dev_s *priv = (FAR struct ram_dev_s *)dev;
    off_t offset;
    off_t maxblock;
    size_t nbytes;
  
    DEBUGASSERT(dev && buf);
  
    /* Don't let the write exceed the size of the ram buffer */
  
    maxblock = priv->nblocks * RAMMTD_BLKPER;
    if (startblock >= maxblock)
      {
        return 0;
      }
  
    if (startblock + nblocks > maxblock)
      {
        nblocks = maxblock - startblock;
      }
  
    /* Get the offset corresponding to the first block and the size
     * corresponding to the number of blocks.
     */
  
    offset = startblock * CONFIG_RAMMTD_BLOCKSIZE;
    nbytes = nblocks * CONFIG_RAMMTD_BLOCKSIZE;
  
    /* Then write the data to RAM */
  
    ram_write(&priv->start[offset], buf, nbytes);
    return nblocks;
  }
  
  /****************************************************************************
   * Name: ram_byteread
   ****************************************************************************/
  
  static ssize_t ram_byteread(FAR struct mtd_dev_s *dev, off_t offset,
                              size_t nbytes, FAR uint8_t *buf)
  {
    FAR struct ram_dev_s *priv = (FAR struct ram_dev_s *)dev;
  
    DEBUGASSERT(dev && buf);
  
    /* Don't let read read past end of buffer */
  
    if (offset + nbytes > priv->nblocks * CONFIG_RAMMTD_ERASESIZE)
     {
       return 0;
     }
  
    ram_read(buf, &priv->start[offset], nbytes);
    return nbytes;
  }
  
  /****************************************************************************
   * Name: ram_bytewrite
   ****************************************************************************/
  
  #ifdef CONFIG_MTD_BYTE_WRITE
  static ssize_t ram_bytewrite(FAR struct mtd_dev_s *dev, off_t offset,
                               size_t nbytes, FAR const uint8_t *buf)
  {
    FAR struct ram_dev_s *priv = (FAR struct ram_dev_s *)dev;
    off_t maxaddr;
  
    DEBUGASSERT(dev && buf);
  
    /* Don't let the write exceed the size of the ram buffer */
  
    maxaddr = priv->nblocks * CONFIG_RAMMTD_ERASESIZE;
    if (offset + nbytes > maxaddr)
      {
        return 0;
      }
  
    /* Then write the data to RAM */
  
    ram_write(&priv->start[offset], buf, nbytes);
    return nbytes;
  }
  #endif
  
  /****************************************************************************
   * Name: ram_ioctl
   ****************************************************************************/
  
  static int ram_ioctl(FAR struct mtd_dev_s *dev, int cmd, unsigned long arg)
  {
    FAR struct ram_dev_s *priv = (FAR struct ram_dev_s *)dev;
    int ret = -EINVAL; /* Assume good command with bad parameters */
  
    switch (cmd)
      {
        case MTDIOC_GEOMETRY:
          {
            FAR struct mtd_geometry_s *geo = (FAR struct mtd_geometry_s *)((uintptr_t)arg);
            if (geo)
              {
                /* Populate the geometry structure with information need to know
                 * the capacity and how to access the device.
                 */
  
                geo->blocksize    = CONFIG_RAMMTD_BLOCKSIZE;
                geo->erasesize    = CONFIG_RAMMTD_ERASESIZE;
                geo->neraseblocks = priv->nblocks;
                ret               = OK;
            }
          }
          break;
  
        case MTDIOC_XIPBASE:
          {
            FAR void **ppv = (FAR void**)((uintptr_t)arg);
            if (ppv)
              {
                /* Return (void*) base address of device memory */
  
                *ppv = (FAR void *)priv->start;
                ret  = OK;
              }
          }
          break;
  
        case MTDIOC_BULKERASE:
          {
              size_t size = priv->nblocks * CONFIG_RAMMTD_ERASESIZE;
  
              /* Erase the entire device */
  
              memset(priv->start, CONFIG_RAMMTD_ERASESTATE, size);
              ret = OK;
          }
          break;
  
        default:
          ret = -ENOTTY; /* Bad command */
          break;
      }
  
    return ret;
  }
  
  /****************************************************************************
   * Public Functions
   ****************************************************************************/
  
  /****************************************************************************
   * Name: rammtd_initialize
   *
   * Description:
   *   Create and initialize a RAM MTD device instance.
   *
   * Input Parameters:
   *   start - Address of the beginning of the allocated RAM regions.
   *   size  - The size in bytes of the allocated RAM region.
   *
   ****************************************************************************/
  
  FAR struct mtd_dev_s *rammtd_initialize(FAR uint8_t *start, size_t size)
  {
    FAR struct ram_dev_s *priv;
    size_t nblocks;
  
    /* Create an instance of the RAM MTD device state structure */
  
    priv = (FAR struct ram_dev_s *)kmm_zalloc(sizeof(struct ram_dev_s));
    if (!priv)
      {
        ferr("ERROR: Failed to allocate the RAM MTD state structure\n");
        return NULL;
      }
  
    /* Force the size to be an even number of the erase block size */
  
    nblocks = size / CONFIG_RAMMTD_ERASESIZE;
    if (nblocks < 1)
      {
        ferr("ERROR: Need to provide at least one full erase block\n");
        return NULL;
      }
  
    /* Perform initialization as necessary. (unsupported methods were
     * nullified by kmm_zalloc).
     */
  
    priv->mtd.erase  = ram_erase;
    priv->mtd.bread  = ram_bread;
    priv->mtd.bwrite = ram_bwrite;
    priv->mtd.read   = ram_byteread;
  #ifdef CONFIG_MTD_BYTE_WRITE
    priv->mtd.write  = ram_bytewrite;
  #endif
    priv->mtd.ioctl  = ram_ioctl;
  
    priv->start      = start;
    priv->nblocks    = nblocks;
  
    /* Register the MTD with the procfs system if enabled */
  
  #ifdef CONFIG_MTD_REGISTRATION
    mtd_register(&priv->mtd, "rammtd");
  #endif
  
    return &priv->mtd;
  }
  