/*********************************************
 * Benjamin Krill <ben@codiert.org>
 *********************************************/
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/init.h>
#include "fpgafs.h"

#define FPGAFS_MAX_LLDRV 3

static struct fpgafs_lldrv *lldrv[FPGAFS_MAX_LLDRV];
static struct fpgafs_lldrv *lldrv_cur;
static int lldrv_count = 0x0;
static DEFINE_SPINLOCK(fpgafs_lldrv_lock);

struct fpga_context* alloc_fpga_context(void)
{
	struct fpga_context *ctx;
	ctx = kzalloc(sizeof *ctx, GFP_KERNEL);
	if (!ctx)
		goto out;

	/* do some stuff */

out:
	return ctx;
}

void free_fpga_context(struct fpga_context *ctx)
{
	if (ctx->load_buf)
		kfree(ctx->load_buf);

	kfree(ctx);
	return;
}

ssize_t fpgafs_send_data(struct file *file, const char __user *buf,
                                size_t len, loff_t *pos)
{
	return (lldrv_cur) ?
		lldrv_cur->send((struct fpga_context*)file->private_data, buf, len)
		: -EBUSY;
}
EXPORT_SYMBOL_GPL(fpgafs_send_data);

ssize_t fpgafs_recv_data(struct file *file, char __user *buf,
                                size_t len, loff_t *pos)
{
	return (lldrv_cur) ?
		lldrv_cur->recv((struct fpga_context*)file->private_data, buf, len)
		: -EBUSY;
}
EXPORT_SYMBOL_GPL(fpgafs_recv_data);

ssize_t fpgafs_write_load(struct file *file, const char __user *buf,
                                size_t len, loff_t *pos)
{
	return (lldrv_cur) ?
		lldrv_cur->write_load((struct fpga_context*)file->private_data, buf, len)
		: -EBUSY;
}
EXPORT_SYMBOL_GPL(fpgafs_write_load);

ssize_t fpgafs_read_load(struct file *file, char __user *buf,
                                size_t len, loff_t *pos)
{
	return (lldrv_cur) ?
		lldrv_cur->read_load((struct fpga_context*)file->private_data, buf, len)
		: -EBUSY;
}
EXPORT_SYMBOL_GPL(fpgafs_read_load);

/* low level un-/register functions */
int fpgafs_register_lldrv(struct fpgafs_lldrv *drv)
{
	unsigned long flags;
	int i;

	spin_lock_irqsave(&fpgafs_lldrv_lock, flags);
	if (lldrv_count == FPGAFS_MAX_LLDRV)
		return -EBUSY;

	/* find free space */
	for(i=0; i < FPGAFS_MAX_LLDRV; i++)
		if (lldrv[lldrv_count] == NULL) {
			lldrv[lldrv_count] = drv;
			break;
		}

	if (lldrv[lldrv_count]->init)
		lldrv[lldrv_count]->init();

	lldrv_cur = lldrv[lldrv_count];

	lldrv_count++;

	spin_unlock_irqrestore(&fpgafs_lldrv_lock, flags);
	return 0;
}
EXPORT_SYMBOL_GPL(fpgafs_register_lldrv);

int fpgafs_unregister_lldrv(struct fpgafs_lldrv *drv)
{
	unsigned long flags;
	int i,k;

	spin_lock_irqsave(&fpgafs_lldrv_lock, flags);

	for(i=0; i < FPGAFS_MAX_LLDRV; i++) {
		if (lldrv[i] == drv) {

			/* call the exit function */
			if (lldrv[i]->exit)
				lldrv[i]->exit();

			lldrv[i] = NULL;

			/* if current, search another low level driver */
			if (lldrv_cur == drv) {
				lldrv_cur = NULL;
				for(k=0; k < FPGAFS_MAX_LLDRV; k++)
					if (lldrv[k]) {
						lldrv_cur = lldrv[k];
						break;
					}
			}
			break;
		}
	}

	lldrv_count--;

	spin_unlock_irqrestore(&fpgafs_lldrv_lock, flags);
	return 0;
}
EXPORT_SYMBOL_GPL(fpgafs_unregister_lldrv);