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mxc_iim.c

/*
 * Copyright 2009 Freescale Semiconductor, Inc. All Rights Reserved.
 */

/*
 * The code contained herein is licensed under the GNU General Public
 * License. You may obtain a copy of the GNU General Public License
 * Version 2 or later at the following locations:
 *
 * http://www.opensource.org/licenses/gpl-license.html
 * http://www.gnu.org/copyleft/gpl.html
 */

#include <linux/fs.h>
#include <linux/init.h>
#include <linux/platform_device.h>
#include <linux/err.h>
#include <linux/mm.h>
#include <linux/clk.h>
#include <linux/miscdevice.h>

static unsigned long iim_reg_base, iim_reg_end, iim_reg_size;
static struct clk *iim_clk;
static struct device *iim_dev;

/*!
 * MXC IIM interface - memory map function
 * This function maps 4KB IIM registers from IIM base address.
 *
 * @param file         struct file *
 * @param vma          structure vm_area_struct *
 *
 * @return       Return 0 on success or negative error code on error
 */
static int mxc_iim_mmap(struct file *file, struct vm_area_struct *vma)
{
      vma->vm_page_prot = pgprot_noncached(vma->vm_page_prot);

      /* Remap-pfn-range will mark the range VM_IO and VM_RESERVED */
      if (remap_pfn_range(vma,
                      vma->vm_start,
                      iim_reg_base >> PAGE_SHIFT,
                      iim_reg_size,
                      vma->vm_page_prot))
            return -EAGAIN;

      return 0;
}

/*!
 * MXC IIM interface - open function
 *
 * @param inode        struct inode *
 * @param filp         struct file *
 *
 * @return       Return 0 on success or negative error code on error
 */
static int mxc_iim_open(struct inode *inode, struct file *filp)
{
      iim_clk = clk_get(NULL, "iim_clk");
      if (IS_ERR(iim_clk)) {
            dev_err(iim_dev, "No IIM clock defined\n");
            return -ENODEV;
      }
      clk_enable(iim_clk);

      return 0;
}

/*!
 * MXC IIM interface - release function
 *
 * @param inode        struct inode *
 * @param filp         struct file *
 *
 * @return       Return 0 on success or negative error code on error
 */
static int mxc_iim_release(struct inode *inode, struct file *filp)
{
      clk_disable(iim_clk);
      clk_put(iim_clk);
      return 0;
}

static const struct file_operations mxc_iim_fops = {
      .mmap = mxc_iim_mmap,
      .open = mxc_iim_open,
      .release = mxc_iim_release,
};

static struct miscdevice mxc_iim_miscdev = {
      .minor = MISC_DYNAMIC_MINOR,
      .name = "mxc_iim",
      .fops = &mxc_iim_fops,
};

/*!
 * This function is called by the driver framework to get iim base/end address
 * and register iim misc device.
 *
 * @param   dev   The device structure for IIM passed in by the driver
 *                framework.
 *
 * @return      Returns 0 on success or negative error code on error
 */
static int mxc_iim_probe(struct platform_device *pdev)
{
      struct resource *res;
      int ret;

      iim_dev = &pdev->dev;

      res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
      if (IS_ERR(res)) {
            dev_err(iim_dev, "Unable to get IIM resource\n");
            return -ENODEV;
      }

      iim_reg_base = res->start;
      iim_reg_end = res->end;
      iim_reg_size = iim_reg_end - iim_reg_base + 1;

      ret = misc_register(&mxc_iim_miscdev);
      if (ret)
            return ret;

      return 0;
}

static int mxc_iim_remove(struct platform_device *pdev)
{
      misc_deregister(&mxc_iim_miscdev);
      return 0;
}

static struct platform_driver mxc_iim_driver = {
      .driver = {
               .owner = THIS_MODULE,
               .name = "mxc_iim",
               },
      .probe = mxc_iim_probe,
      .remove = mxc_iim_remove,
};

static int __init mxc_iim_dev_init(void)
{
      return platform_driver_register(&mxc_iim_driver);
}

static void __exit mxc_iim_dev_cleanup(void)
{
      platform_driver_unregister(&mxc_iim_driver);
}

module_init(mxc_iim_dev_init);
module_exit(mxc_iim_dev_cleanup);

MODULE_AUTHOR("Freescale Semiconductor, Inc.");
MODULE_DESCRIPTION("MXC IIM driver");
MODULE_LICENSE("GPL");
MODULE_ALIAS_MISCDEV(MISC_DYNAMIC_MINOR);

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