/*
 * American Megatrends ROM Driver
 * There wasn't a copyright here, so idk
 */

#include <asm/io.h>
#include <linux/version.h>
#include <linux/mm.h>
#include <linux/interrupt.h>
#include <linux/module.h>
#include <linux/slab.h>
#include <linux/kernel.h>
#include <linux/fs.h>
#include <linux/version.h>

#define LINUX_PRE_2_6   (LINUX_VERSION_CODE <  KERNEL_VERSION(2, 6, 0))
#define LINUX_POST_2_6  (LINUX_VERSION_CODE >= KERNEL_VERSION(2, 6, 0))

#if LINUX_PRE_2_6
#include <linux/wrapper.h>
#else
#define mem_map_reserve(p)   set_bit  (PG_reserved, &((p)->flags))
#define mem_map_unreserve(p) clear_bit(PG_reserved, &((p)->flags))
#endif

#define CMD_ALLOC       0x4160
#define CMD_FREE        0x4161
#define CMD_LOCK_KB     0x4162
#define CMD_UNLOCK_KB   0x4163

/*
 * ioctl data packet used to communicate instructions to the driver
 */
typedef struct _struct_AMIFL_alloc_params {
	long size;
	unsigned long kvirtlen;
	void *kmallocptr;
	void *kvirtadd;
	void *kphysadd;
} AMIFL_alloc_params;

static int *kmalloc_area = NULL;
static int *kmalloc_ptr = NULL;
static unsigned long kmalloc_len = 0L;
static int kcount = 0;
static int major;
static AMIFL_alloc_params kmalloc_drv[128];

/*
 * Section: Character Device Implementation
 * ============================================================================
 */

#if LINUX_POST_2_6
static int chardev_open_count = 0;
#endif

/**
 * Character Device open action
 */
int AMI_chrdrv_open(struct inode *inode, struct file *file)
{
#if LINUX_PRE_2_6
	MOD_INC_USE_COUNT;
#else
	if (chardev_open_count > 0) {
		return -EBUSY;
	}

	++chardev_open_count;
	try_module_get(THIS_MODULE);
#endif

	return (0);
}

int AMI_chrdrv_release(struct inode *inode, struct file *file)
{
#if LINUX_PRE_2_6
	MOD_DEC_USE_COUNT;
#else
	--chardev_open_count;
	module_put(THIS_MODULE);
#endif

	return (0);
}

#if defined(HAVE_UNLOCKED_IOCTL)
long AMI_chrdrv_ioctl(struct file *_unused_file, unsigned int cmd, unsigned long arg)
#else
int AMI_chrdrv_ioctl(struct inode *_unused_inode, unsigned int cmd, unsigned long arg)
#endif
{
	switch (cmd) {
	case CMD_ALLOC:
		{
			unsigned long virt_addr;
			AMIFL_alloc_params arg_kernel_space;

			if (kcount >= 128) {
				return -EINVAL;
			}

			kmalloc_ptr = NULL;

			if (!arg || kmalloc_ptr) {
				return -EINVAL;
			}

			copy_from_user((void *) &arg_kernel_space, (void *) arg,
				       sizeof(AMIFL_alloc_params));

			if (arg_kernel_space.size > 128 * 1024) {
				return -EINVAL;
			}

			kmalloc_len = ((arg_kernel_space.size + PAGE_SIZE - 1) & PAGE_MASK);
			kmalloc_ptr = kmalloc((kmalloc_len + 2 * PAGE_SIZE), GFP_DMA | GFP_KERNEL);
			kmalloc_area =
			    (int *) (((unsigned long) kmalloc_ptr + PAGE_SIZE - 1) & PAGE_MASK);

			for (virt_addr = (unsigned long) kmalloc_area;
			     virt_addr < (unsigned long) kmalloc_area + kmalloc_len;
			     virt_addr += PAGE_SIZE) {
				mem_map_reserve(virt_to_page(virt_addr));
			}

			{
				int i;
				for (i = 0; i < (kmalloc_len / sizeof(int)); ++i) {
					kmalloc_area[i] = 0xAFD00000 + i;
				}
			}

			kmalloc_drv[kcount].size = arg_kernel_space.size;
			kmalloc_drv[kcount].kmallocptr = kmalloc_ptr;
			kmalloc_drv[kcount].kvirtlen = kmalloc_len;
			kmalloc_drv[kcount].kvirtadd = kmalloc_area;
			kmalloc_drv[kcount].kphysadd =
			    (void *) ((unsigned long) virt_to_phys(kmalloc_area));
			++kcount;

			arg_kernel_space.kvirtadd = kmalloc_area;
			arg_kernel_space.kphysadd =
			    (void *) ((unsigned long) virt_to_phys(kmalloc_area));

			copy_to_user((void *) arg, (void *) &arg_kernel_space,
				     sizeof(AMIFL_alloc_params));

			return 0;
		}
	case CMD_FREE:
		{
			unsigned long virt_addr;
			AMIFL_alloc_params arg_kernel_space;
			int isearch = 0;

			copy_from_user((void *) &arg_kernel_space, (void *) arg,
				       sizeof(AMIFL_alloc_params));

			if (kcount > 0) {
				for (isearch = 0; isearch < kcount; isearch++) {
					if (kmalloc_drv[isearch].kphysadd ==
					    arg_kernel_space.kphysadd)
						break;
				}
				if (isearch >= kcount)
					return 0;
				kmalloc_ptr = kmalloc_drv[isearch].kmallocptr;
				kmalloc_area = kmalloc_drv[isearch].kvirtadd;
				kmalloc_len = kmalloc_drv[isearch].kvirtlen;
			} else
				return 0;
			if (kmalloc_ptr) {
				for (virt_addr = (unsigned long) kmalloc_area;
				     virt_addr < (unsigned long) kmalloc_area + kmalloc_len;
				     virt_addr += PAGE_SIZE) {
					mem_map_unreserve(virt_to_page(virt_addr));
				}

				if (kmalloc_ptr) {
					kfree(kmalloc_ptr);
				}

				kmalloc_len = 0L;
				kmalloc_ptr = NULL;
				kmalloc_area = NULL;
				kcount--;

				if (isearch != kcount) {
					kmalloc_drv[isearch].size = kmalloc_drv[kcount].size;
					kmalloc_drv[isearch].kmallocptr =
					    kmalloc_drv[kcount].kmallocptr;
					kmalloc_drv[isearch].kvirtlen =
					    kmalloc_drv[kcount].kvirtlen;
					kmalloc_drv[isearch].kvirtadd =
					    kmalloc_drv[kcount].kvirtadd;
					kmalloc_drv[isearch].kphysadd =
					    kmalloc_drv[kcount].kphysadd;
				}

				kmalloc_drv[kcount].size = 0;
				kmalloc_drv[kcount].kmallocptr = NULL;
				kmalloc_drv[kcount].kvirtlen = 0;
				kmalloc_drv[kcount].kvirtadd = NULL;
				kmalloc_drv[kcount].kphysadd = NULL;
			}
			return 0;
		}
	case CMD_LOCK_KB:
		disable_irq(1);
		return 0;
	case CMD_UNLOCK_KB:
		enable_irq(1);
		return 0;
	}
	return -ENOTTY;
}

int AMI_chrdrv_mmap(struct file *file, struct vm_area_struct *vma)
{
	unsigned long offset = vma->vm_pgoff << PAGE_SHIFT;
	unsigned long size = vma->vm_end - vma->vm_start;

	if (offset & ~PAGE_MASK) {
		return -ENXIO;
	}
	if (!kmalloc_ptr) {
		return (-ENXIO);
	}
	if (size > kmalloc_len) {
		return (-ENXIO);
	}
	if ((offset + size) > kmalloc_len) {
		return -ENXIO;
	}
	if ((vma->vm_flags & VM_WRITE) && !(vma->vm_flags & VM_SHARED)) {
		return (-EINVAL);
	}

	vma->vm_flags |= VM_LOCKED;

	{
		unsigned long pfn = virt_to_phys((void *) ((unsigned long) kmalloc_area));

#if LINUX_POST_2_6
		int remap_result = remap_pfn_range(vma,
						   vma->vm_start,
						   pfn >> PAGE_SHIFT,
						   size,
						   PAGE_SHARED);
#else
		int remap_result = remap_page_range(vma,
						    vma->vm_start,
						    pfn,
						    size,
						    PAGE_SHARED);
#endif

		if (remap_result) {
			return -ENXIO;
		}
	}

	return (0);
}

#if defined(HAVE_UNLOCKED_IOCTL)
#define $IOCTL_FIELD unlocked_ioctl
#else
#define $IOCTL_FIELD ioctl
#endif

struct file_operations AMI_chrdrv_fops = {
      owner:THIS_MODULE,
      open:AMI_chrdrv_open,
      release:AMI_chrdrv_release,
      mmap:AMI_chrdrv_mmap,
      $IOCTL_FIELD:AMI_chrdrv_ioctl,
};

/*
 * Section: Linux Kernel Module Setup 
 * ============================================================================
 */

#if LINUX_POST_2_6

MODULE_AUTHOR("American Megatrends Inc.");
MODULE_DESCRIPTION("AMI Flash Update utility driver");
MODULE_LICENSE("Proprietary");

#endif

static int /* module_init */ amifldrv_init_module(void)
{
	major = register_chrdev(0, "amifldrv", &AMI_chrdrv_fops);

	if (major < 0) {
		return -EIO;
	}

	memset(kmalloc_drv, 0, sizeof(AMIFL_alloc_params) * 128);

	return (0);
}

static void /* module_exit */ amifldrv_cleanup_module(void)
{
	unsigned long virt_addr;
	if (kcount > 0) {
		{
			int iloop;
			for (iloop = 0; iloop < kcount; ++iloop) {
				kmalloc_ptr = kmalloc_drv[iloop].kmallocptr;
				kmalloc_area = kmalloc_drv[iloop].kvirtadd;
				kmalloc_len = kmalloc_drv[iloop].kvirtlen;
				if (kmalloc_ptr) {
					for (virt_addr = (unsigned long) kmalloc_area;
					     virt_addr < (unsigned long) kmalloc_area + kmalloc_len;
					     virt_addr += PAGE_SIZE) {
						mem_map_unreserve(virt_to_page(virt_addr));
					}

					if (kmalloc_ptr) {
						kfree(kmalloc_ptr);
					}
				}
			}
		}
		kcount = 0;
	}

	unregister_chrdev(major, "amifldrv");

	return;
}

module_init(amifldrv_init_module);
module_exit(amifldrv_cleanup_module);