/*
 * jvdg_usbgadget driver as kernel module - sysfs interface
 *
 * Copyright (C) 2011 Julien Viard de Galbert
 *
 *	This program is free software; you can redistribute it and/or
 *	modify it under the terms of the GNU General Public License as
 *	published by the Free Software Foundation, version 2.
 *
 * written using those tutorials as support:
 * - http://linuxdevcenter.com/pub/a/linux/2007/07/05/devhelloworld-a-simple-introduction-to-device-drivers-under-linux.html by Valerie Henson
 * - http://www.linuxjournal.com/article/7353 by Greg Kroah-Hartman
 */

#define DEBUG

#include <linux/errno.h>
#include <linux/init.h>
#include <linux/module.h>
#include <linux/usb.h>

/* Ids form our USBTiny config */
#define VENDOR_ID	0x6666
#define PRODUCT_ID	0x0001

/* Commands from our USB device AVR code */
enum
{
	// Generic requests
	USBTINY_ECHO,		// echo test
	USBTINY_READ,		// read byte
	USBTINY_WRITE,		// write byte
	USBTINY_CLR,		// clear bit 
	USBTINY_SET,		// set bit
	//
	USBTINY_KEY_READ	// read key status
};


/* table of devices that work with this driver */
static struct usb_device_id id_table [] = {
	{ USB_DEVICE(VENDOR_ID, PRODUCT_ID) },
	{ },
};
MODULE_DEVICE_TABLE (usb, id_table);


struct jvdg_usbg {
	struct usb_device *	udev;
	unsigned char		leds;
	unsigned char		keys;
};

static void change_leds(struct jvdg_usbg *dev)
{
	int retval;
	unsigned char *buffer;

	buffer = kmalloc(8, GFP_KERNEL);
	if (!buffer) {
		dev_err(&dev->udev->dev, "out of memory\n");
		return;
	}

	dev_dbg(&dev->udev->dev, "leds = %.2x\n", dev->leds);

	retval = usb_control_msg(dev->udev,
				usb_sndctrlpipe(dev->udev, 0),
				USBTINY_WRITE,
				0xc0,
				dev->leds,
				1,
				buffer,
				0,
				2000);
	if (retval)
		dev_dbg(&dev->udev->dev, "retval = %d\n", retval);
	kfree(buffer);
}

static void read_leds(struct jvdg_usbg *dev)
{
	int retval;
	unsigned char *buffer;

	buffer = kmalloc(8, GFP_KERNEL);
	if (!buffer) {
		dev_err(&dev->udev->dev, "out of memory\n");
		return;
	}

	retval = usb_control_msg(dev->udev,
				usb_rcvctrlpipe(dev->udev, 0),
				USBTINY_READ,
				0xc0,
				0,
				0,
				buffer,
				1,
				2000);

	if (retval)
		dev_dbg(&dev->udev->dev, "retval = %d\n", retval);

	dev->leds = buffer[0];
	dev_dbg(&dev->udev->dev, "leds = %.2x\n", dev->leds);

	kfree(buffer);
}


static void read_keys(struct jvdg_usbg *dev)
{
	int retval;
	unsigned char *buffer;

	buffer = kmalloc(8, GFP_KERNEL);
	if (!buffer) {
		dev_err(&dev->udev->dev, "out of memory\n");
		return;
	}

	retval = usb_control_msg(dev->udev,
				usb_rcvctrlpipe(dev->udev, 0),
				USBTINY_KEY_READ,
				0xc0,
				0,
				0,
				buffer,	
				1,
				2000);

	if (retval)
		dev_dbg(&dev->udev->dev, "retval = %d\n", retval);

	dev->keys = buffer[0];
	dev_dbg(&dev->udev->dev, "keys = %.2x\n", dev->keys);

	kfree(buffer);
}


static ssize_t show_leds(struct device *dev, struct device_attribute *attr, char *buf)
{
	struct usb_interface *intf = to_usb_interface(dev);
	struct jvdg_usbg *led = usb_get_intfdata(intf);

	read_leds(led);

	return sprintf(buf, "%d\n", led->leds);
}

static ssize_t set_leds(struct device *dev, struct device_attribute *attr, const char *buf, size_t count)
{
	struct usb_interface *intf = to_usb_interface(dev);
	struct jvdg_usbg *led = usb_get_intfdata(intf);
	int temp = simple_strtoul(buf, NULL, 0);

	led->leds = temp & 0xf;
	change_leds(led);
	return count;
}

static DEVICE_ATTR(leds, S_IRUGO | S_IWUSR, show_leds, set_leds);


static ssize_t show_keys(struct device *dev, struct device_attribute *attr, char *buf)
{
	struct usb_interface *intf = to_usb_interface(dev);
	struct jvdg_usbg *keys = usb_get_intfdata(intf);

	read_keys(keys);

	return sprintf(buf, "%d\n", keys->keys);
}

static DEVICE_ATTR(keys, S_IRUGO, show_keys, NULL);



static int jvdg_usbg_probe(struct usb_interface *interface, const struct usb_device_id *id)
{
	struct usb_device *udev = interface_to_usbdev(interface);
	struct jvdg_usbg *dev = NULL;
	int retval = -ENOMEM;

	dev = kzalloc(sizeof(struct jvdg_usbg), GFP_KERNEL);
	if (dev == NULL) {
		dev_err(&interface->dev, "Out of memory\n");
		goto error_mem;
	}

	dev->udev = usb_get_dev(udev);

	usb_set_intfdata (interface, dev);

	retval = device_create_file(&interface->dev, &dev_attr_leds);
	if (retval)
		goto error;

	retval = device_create_file(&interface->dev, &dev_attr_keys);
	if (retval)
		goto error;

	dev_info(&interface->dev, "jvdg USBGadget device now attached\n");
	return 0;

error:
	device_remove_file(&interface->dev, &dev_attr_leds);
	device_remove_file(&interface->dev, &dev_attr_keys);
	usb_set_intfdata (interface, NULL);
	usb_put_dev(dev->udev);
	kfree(dev);
error_mem:
	return retval;
}

static void jvdg_usbg_disconnect(struct usb_interface *interface)
{
	struct jvdg_usbg *dev;

	dev = usb_get_intfdata (interface);

	device_remove_file(&interface->dev, &dev_attr_leds);
	device_remove_file(&interface->dev, &dev_attr_keys);

	/* first remove the files, then set the pointer to NULL */
	usb_set_intfdata (interface, NULL);

	usb_put_dev(dev->udev);

	kfree(dev);

	dev_info(&interface->dev, "jvdg USBGadget now disconnected\n");
}


static struct usb_driver jvdg_usbg_driver = {
	.name =		"jvdg_usbgadget",
	.probe =	jvdg_usbg_probe,
	.disconnect =	jvdg_usbg_disconnect,
	.id_table =	id_table,
};

static int __init jvdg_usbg_init(void)
{
	int retval = 0;

	retval = usb_register(&jvdg_usbg_driver);
	if (retval)
		err("usb_register failed. Error number %d", retval);
	return retval;
}

static void __exit jvdg_usbg_exit(void)
{
	usb_deregister(&jvdg_usbg_driver);
}

module_init (jvdg_usbg_init);
module_exit (jvdg_usbg_exit);

MODULE_AUTHOR("Julien Viard de Galbert <julien@silicone.homelinux.org>");
MODULE_DESCRIPTION("JVdG USB Gadget Driver");
MODULE_LICENSE("GPL");