/*
   * Input driver to ExplorerPS/2 device driver module.
   *
   * Copyright (c) 1999-2002 Vojtech Pavlik
   * Copyright (c) 2004      Dmitry Torokhov
   *
   * This program is free software; you can redistribute it and/or modify
   * it under the terms of the GNU General Public License version 2 as published by
   * the Free Software Foundation.
   */
  
  #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
  
  #define MOUSEDEV_MINOR_BASE	32
  #define MOUSEDEV_MINORS		31
  #define MOUSEDEV_MIX		63
  
  #include <linux/sched.h>
  #include <linux/slab.h>
  #include <linux/poll.h>
  #include <linux/module.h>
  #include <linux/init.h>
  #include <linux/input.h>
  #include <linux/random.h>
  #include <linux/major.h>
  #include <linux/device.h>
  #include <linux/cdev.h>
  #include <linux/kernel.h>
  
  MODULE_AUTHOR("Vojtech Pavlik <vojtech@ucw.cz>");
  MODULE_DESCRIPTION("Mouse (ExplorerPS/2) device interfaces");
  MODULE_LICENSE("GPL");
  
  #ifndef CONFIG_INPUT_MOUSEDEV_SCREEN_X
  #define CONFIG_INPUT_MOUSEDEV_SCREEN_X	1024
  #endif
  #ifndef CONFIG_INPUT_MOUSEDEV_SCREEN_Y
  #define CONFIG_INPUT_MOUSEDEV_SCREEN_Y	768
  #endif
  
  static int xres = CONFIG_INPUT_MOUSEDEV_SCREEN_X;
  module_param(xres, uint, 0644);
  MODULE_PARM_DESC(xres, "Horizontal screen resolution");
  
  static int yres = CONFIG_INPUT_MOUSEDEV_SCREEN_Y;
  module_param(yres, uint, 0644);
  MODULE_PARM_DESC(yres, "Vertical screen resolution");
  
  static unsigned tap_time = 200;
  module_param(tap_time, uint, 0644);
  MODULE_PARM_DESC(tap_time, "Tap time for touchpads in absolute mode (msecs)");
  
  struct mousedev_hw_data {
  	int dx, dy, dz;
  	int x, y;
  	int abs_event;
  	unsigned long buttons;
  };
  
  struct mousedev {
  	int open;
  	struct input_handle handle;
  	wait_queue_head_t wait;
  	struct list_head client_list;
  	spinlock_t client_lock; /* protects client_list */
  	struct mutex mutex;
  	struct device dev;
  	struct cdev cdev;
  	bool exist;
  
  	struct list_head mixdev_node;
  	bool opened_by_mixdev;
  
  	struct mousedev_hw_data packet;
  	unsigned int pkt_count;
  	int old_x[4], old_y[4];
  	int frac_dx, frac_dy;
  	unsigned long touch;
  
  	int (*open_device)(struct mousedev *mousedev);
  	void (*close_device)(struct mousedev *mousedev);
  };
  
  enum mousedev_emul {
  	MOUSEDEV_EMUL_PS2,
  	MOUSEDEV_EMUL_IMPS,
  	MOUSEDEV_EMUL_EXPS
  };
  
  struct mousedev_motion {
  	int dx, dy, dz;
  	unsigned long buttons;
  };
  
  #define PACKET_QUEUE_LEN	16
  struct mousedev_client {
  	struct fasync_struct *fasync;
  	struct mousedev *mousedev;
  	struct list_head node;
  
  	struct mousedev_motion packets[PACKET_QUEUE_LEN];
  	unsigned int head, tail;
  	spinlock_t packet_lock;
  	int pos_x, pos_y;
  
  	signed char ps2[6];
  	unsigned char ready, buffer, bufsiz;
  	unsigned char imexseq, impsseq;
  	enum mousedev_emul mode;
  	unsigned long last_buttons;
  };
  
  #define MOUSEDEV_SEQ_LEN	6
  
  static unsigned char mousedev_imps_seq[] = { 0xf3, 200, 0xf3, 100, 0xf3, 80 };
  static unsigned char mousedev_imex_seq[] = { 0xf3, 200, 0xf3, 200, 0xf3, 80 };
  
  static struct mousedev *mousedev_mix;
  static LIST_HEAD(mousedev_mix_list);
  
  #define fx(i)  (mousedev->old_x[(mousedev->pkt_count - (i)) & 03])
  #define fy(i)  (mousedev->old_y[(mousedev->pkt_count - (i)) & 03])
  
  static void mousedev_touchpad_event(struct input_dev *dev,
  				    struct mousedev *mousedev,
  				    unsigned int code, int value)
  {
  	int size, tmp;
  	enum { FRACTION_DENOM = 128 };
  
  	switch (code) {
  
  	case ABS_X:
  
  		fx(0) = value;
  		if (mousedev->touch && mousedev->pkt_count >= 2) {
  			size = input_abs_get_max(dev, ABS_X) -
  					input_abs_get_min(dev, ABS_X);
  			if (size == 0)
  				size = 256 * 2;
  
  			tmp = ((value - fx(2)) * 256 * FRACTION_DENOM) / size;
  			tmp += mousedev->frac_dx;
  			mousedev->packet.dx = tmp / FRACTION_DENOM;
  			mousedev->frac_dx =
  				tmp - mousedev->packet.dx * FRACTION_DENOM;
  		}
  		break;
  
  	case ABS_Y:
  		fy(0) = value;
  		if (mousedev->touch && mousedev->pkt_count >= 2) {
  			/* use X size for ABS_Y to keep the same scale */
  			size = input_abs_get_max(dev, ABS_X) -
  					input_abs_get_min(dev, ABS_X);
  			if (size == 0)
  				size = 256 * 2;
  
  			tmp = -((value - fy(2)) * 256 * FRACTION_DENOM) / size;
  			tmp += mousedev->frac_dy;
  			mousedev->packet.dy = tmp / FRACTION_DENOM;
  			mousedev->frac_dy = tmp -
  				mousedev->packet.dy * FRACTION_DENOM;
  		}
  		break;
  	}
  }
  
  static void mousedev_abs_event(struct input_dev *dev, struct mousedev *mousedev,
  				unsigned int code, int value)
  {
  	int min, max, size;
  
  	switch (code) {
  
  	case ABS_X:
  		min = input_abs_get_min(dev, ABS_X);
  		max = input_abs_get_max(dev, ABS_X);
  
  		size = max - min;
  		if (size == 0)
  			size = xres ? : 1;
  
  		value = clamp(value, min, max);
  
  		mousedev->packet.x = ((value - min) * xres) / size;
  		mousedev->packet.abs_event = 1;
  		break;
  
  	case ABS_Y:
  		min = input_abs_get_min(dev, ABS_Y);
  		max = input_abs_get_max(dev, ABS_Y);
  
  		size = max - min;
  		if (size == 0)
  			size = yres ? : 1;
  
  		value = clamp(value, min, max);
  
  		mousedev->packet.y = yres - ((value - min) * yres) / size;
  		mousedev->packet.abs_event = 1;
  		break;
  	}
  }
  
  static void mousedev_rel_event(struct mousedev *mousedev,
  				unsigned int code, int value)
  {
  	switch (code) {
  	case REL_X:
  		mousedev->packet.dx += value;
  		break;
  
  	case REL_Y:
  		mousedev->packet.dy -= value;
  		break;
  
  	case REL_WHEEL:
  		mousedev->packet.dz -= value;
  		break;
  	}
  }
  
  static void mousedev_key_event(struct mousedev *mousedev,
  				unsigned int code, int value)
  {
  	int index;
  
  	switch (code) {
  
  	case BTN_TOUCH:
  	case BTN_0:
  	case BTN_LEFT:		index = 0; break;
  
  	case BTN_STYLUS:
  	case BTN_1:
  	case BTN_RIGHT:		index = 1; break;
  
  	case BTN_2:
  	case BTN_FORWARD:
  	case BTN_STYLUS2:
  	case BTN_MIDDLE:	index = 2; break;
  
  	case BTN_3:
  	case BTN_BACK:
  	case BTN_SIDE:		index = 3; break;
  
  	case BTN_4:
  	case BTN_EXTRA:		index = 4; break;
  
  	default:		return;
  	}
  
  	if (value) {
  		set_bit(index, &mousedev->packet.buttons);
  		set_bit(index, &mousedev_mix->packet.buttons);
  	} else {
  		clear_bit(index, &mousedev->packet.buttons);
  		clear_bit(index, &mousedev_mix->packet.buttons);
  	}
  }
  
  static void mousedev_notify_readers(struct mousedev *mousedev,
  				    struct mousedev_hw_data *packet)
  {
  	struct mousedev_client *client;
  	struct mousedev_motion *p;
  	unsigned int new_head;
  	int wake_readers = 0;
  
  	rcu_read_lock();
  	list_for_each_entry_rcu(client, &mousedev->client_list, node) {
  
  		/* Just acquire the lock, interrupts already disabled */
  		spin_lock(&client->packet_lock);
  
  		p = &client->packets[client->head];
  		if (client->ready && p->buttons != mousedev->packet.buttons) {
  			new_head = (client->head + 1) % PACKET_QUEUE_LEN;
  			if (new_head != client->tail) {
  				p = &client->packets[client->head = new_head];
  				memset(p, 0, sizeof(struct mousedev_motion));
  			}
  		}
  
  		if (packet->abs_event) {
  			p->dx += packet->x - client->pos_x;
  			p->dy += packet->y - client->pos_y;
  			client->pos_x = packet->x;
  			client->pos_y = packet->y;
  		}
  
  		client->pos_x += packet->dx;
  		client->pos_x = client->pos_x < 0 ?
  			0 : (client->pos_x >= xres ? xres : client->pos_x);
  		client->pos_y += packet->dy;
  		client->pos_y = client->pos_y < 0 ?
  			0 : (client->pos_y >= yres ? yres : client->pos_y);
  
  		p->dx += packet->dx;
  		p->dy += packet->dy;
  		p->dz += packet->dz;
  		p->buttons = mousedev->packet.buttons;
  
  		if (p->dx || p->dy || p->dz ||
  		    p->buttons != client->last_buttons)
  			client->ready = 1;
  
  		spin_unlock(&client->packet_lock);
  
  		if (client->ready) {
  			kill_fasync(&client->fasync, SIGIO, POLL_IN);
  			wake_readers = 1;
  		}
  	}
  	rcu_read_unlock();
  
  	if (wake_readers)
  		wake_up_interruptible(&mousedev->wait);
  }
  
  static void mousedev_touchpad_touch(struct mousedev *mousedev, int value)
  {
  	if (!value) {
  		if (mousedev->touch &&
  		    time_before(jiffies,
  				mousedev->touch + msecs_to_jiffies(tap_time))) {
  			/*
  			 * Toggle left button to emulate tap.
  			 * We rely on the fact that mousedev_mix always has 0
  			 * motion packet so we won't mess current position.
  			 */
  			set_bit(0, &mousedev->packet.buttons);
  			set_bit(0, &mousedev_mix->packet.buttons);
  			mousedev_notify_readers(mousedev, &mousedev_mix->packet);
  			mousedev_notify_readers(mousedev_mix,
  						&mousedev_mix->packet);
  			clear_bit(0, &mousedev->packet.buttons);
  			clear_bit(0, &mousedev_mix->packet.buttons);
  		}
  		mousedev->touch = mousedev->pkt_count = 0;
  		mousedev->frac_dx = 0;
  		mousedev->frac_dy = 0;
  
  	} else if (!mousedev->touch)
  		mousedev->touch = jiffies;
  }
  
  static void mousedev_event(struct input_handle *handle,
  			   unsigned int type, unsigned int code, int value)
  {
  	struct mousedev *mousedev = handle->private;
  
  	switch (type) {
  
  	case EV_ABS:
  		/* Ignore joysticks */
  		if (test_bit(BTN_TRIGGER, handle->dev->keybit))
  			return;
  
  		if (test_bit(BTN_TOOL_FINGER, handle->dev->keybit))
  			mousedev_touchpad_event(handle->dev,
  						mousedev, code, value);
  		else
  			mousedev_abs_event(handle->dev, mousedev, code, value);
  
  		break;
  
  	case EV_REL:
  		mousedev_rel_event(mousedev, code, value);
  		break;
  
  	case EV_KEY:
  		if (value != 2) {
  			if (code == BTN_TOUCH &&
  			    test_bit(BTN_TOOL_FINGER, handle->dev->keybit))
  				mousedev_touchpad_touch(mousedev, value);
  			else
  				mousedev_key_event(mousedev, code, value);
  		}
  		break;
  
  	case EV_SYN:
  		if (code == SYN_REPORT) {
  			if (mousedev->touch) {
  				mousedev->pkt_count++;
  				/*
  				 * Input system eats duplicate events,
  				 * but we need all of them to do correct
  				 * averaging so apply present one forward
  				 */
  				fx(0) = fx(1);
  				fy(0) = fy(1);
  			}
  
  			mousedev_notify_readers(mousedev, &mousedev->packet);
  			mousedev_notify_readers(mousedev_mix, &mousedev->packet);
  
  			mousedev->packet.dx = mousedev->packet.dy =
  				mousedev->packet.dz = 0;
  			mousedev->packet.abs_event = 0;
  		}
  		break;
  	}
  }
  
  static int mousedev_fasync(int fd, struct file *file, int on)
  {
  	struct mousedev_client *client = file->private_data;
  
  	return fasync_helper(fd, file, on, &client->fasync);
  }
  
  static void mousedev_free(struct device *dev)
  {
  	struct mousedev *mousedev = container_of(dev, struct mousedev, dev);
  
  	input_put_device(mousedev->handle.dev);
  	kfree(mousedev);
  }
  
  static int mousedev_open_device(struct mousedev *mousedev)
  {
  	int retval;
  
  	retval = mutex_lock_interruptible(&mousedev->mutex);
  	if (retval)
  		return retval;
  
  	if (!mousedev->exist)
  		retval = -ENODEV;
  	else if (!mousedev->open++) {
  		retval = input_open_device(&mousedev->handle);
  		if (retval)
  			mousedev->open--;
  	}
  
  	mutex_unlock(&mousedev->mutex);
  	return retval;
  }
  
  static void mousedev_close_device(struct mousedev *mousedev)
  {
  	mutex_lock(&mousedev->mutex);
  
  	if (mousedev->exist && !--mousedev->open)
  		input_close_device(&mousedev->handle);
  
  	mutex_unlock(&mousedev->mutex);
  }
  
  /*
   * Open all available devices so they can all be multiplexed in one.
   * stream. Note that this function is called with mousedev_mix->mutex
   * held.
   */
  static int mixdev_open_devices(struct mousedev *mixdev)
  {
  	int error;
  
  	error = mutex_lock_interruptible(&mixdev->mutex);
  	if (error)
  		return error;
  
  	if (!mixdev->open++) {
  		struct mousedev *mousedev;
  
  		list_for_each_entry(mousedev, &mousedev_mix_list, mixdev_node) {
  			if (!mousedev->opened_by_mixdev) {
  				if (mousedev_open_device(mousedev))
  					continue;
  
  				mousedev->opened_by_mixdev = true;
  			}
  		}
  	}
  
  	mutex_unlock(&mixdev->mutex);
  	return 0;
  }
  
  /*
   * Close all devices that were opened as part of multiplexed
   * device. Note that this function is called with mousedev_mix->mutex
   * held.
   */
  static void mixdev_close_devices(struct mousedev *mixdev)
  {
  	mutex_lock(&mixdev->mutex);
  
  	if (!--mixdev->open) {
  		struct mousedev *mousedev;
  
  		list_for_each_entry(mousedev, &mousedev_mix_list, mixdev_node) {
  			if (mousedev->opened_by_mixdev) {
  				mousedev->opened_by_mixdev = false;
  				mousedev_close_device(mousedev);
  			}
  		}
  	}
  
  	mutex_unlock(&mixdev->mutex);
  }
  
  
  static void mousedev_attach_client(struct mousedev *mousedev,
  				   struct mousedev_client *client)
  {
  	spin_lock(&mousedev->client_lock);
  	list_add_tail_rcu(&client->node, &mousedev->client_list);
  	spin_unlock(&mousedev->client_lock);
  }
  
  static void mousedev_detach_client(struct mousedev *mousedev,
  				   struct mousedev_client *client)
  {
  	spin_lock(&mousedev->client_lock);
  	list_del_rcu(&client->node);
  	spin_unlock(&mousedev->client_lock);
  	synchronize_rcu();
  }
  
  static int mousedev_release(struct inode *inode, struct file *file)
  {
  	struct mousedev_client *client = file->private_data;
  	struct mousedev *mousedev = client->mousedev;
  
  	mousedev_detach_client(mousedev, client);
  	kfree(client);
  
  	mousedev->close_device(mousedev);
  
  	return 0;
  }
  
  static int mousedev_open(struct inode *inode, struct file *file)
  {
  	struct mousedev_client *client;
  	struct mousedev *mousedev;
  	int error;
  
  #ifdef CONFIG_INPUT_MOUSEDEV_PSAUX
  	if (imajor(inode) == MISC_MAJOR)
  		mousedev = mousedev_mix;
  	else
  #endif
  		mousedev = container_of(inode->i_cdev, struct mousedev, cdev);
  
  	client = kzalloc(sizeof(struct mousedev_client), GFP_KERNEL);
  	if (!client)
  		return -ENOMEM;
  
  	spin_lock_init(&client->packet_lock);
  	client->pos_x = xres / 2;
  	client->pos_y = yres / 2;
  	client->mousedev = mousedev;
  	mousedev_attach_client(mousedev, client);
  
  	error = mousedev->open_device(mousedev);
  	if (error)
  		goto err_free_client;
  
  	file->private_data = client;
  	nonseekable_open(inode, file);
  
  	return 0;
  
   err_free_client:
  	mousedev_detach_client(mousedev, client);
  	kfree(client);
  	return error;
  }
  
  static inline int mousedev_limit_delta(int delta, int limit)
  {
  	return delta > limit ? limit : (delta < -limit ? -limit : delta);
  }
  
  static void mousedev_packet(struct mousedev_client *client,
  			    signed char *ps2_data)
  {
  	struct mousedev_motion *p = &client->packets[client->tail];
  
  	ps2_data[0] = 0x08 |
  		((p->dx < 0) << 4) | ((p->dy < 0) << 5) | (p->buttons & 0x07);
  	ps2_data[1] = mousedev_limit_delta(p->dx, 127);
  	ps2_data[2] = mousedev_limit_delta(p->dy, 127);
  	p->dx -= ps2_data[1];
  	p->dy -= ps2_data[2];
  
  	switch (client->mode) {
  	case MOUSEDEV_EMUL_EXPS:
  		ps2_data[3] = mousedev_limit_delta(p->dz, 7);
  		p->dz -= ps2_data[3];
  		ps2_data[3] = (ps2_data[3] & 0x0f) | ((p->buttons & 0x18) << 1);
  		client->bufsiz = 4;
  		break;
  
  	case MOUSEDEV_EMUL_IMPS:
  		ps2_data[0] |=
  			((p->buttons & 0x10) >> 3) | ((p->buttons & 0x08) >> 1);
  		ps2_data[3] = mousedev_limit_delta(p->dz, 127);
  		p->dz -= ps2_data[3];
  		client->bufsiz = 4;
  		break;
  
  	case MOUSEDEV_EMUL_PS2:
  	default:
  		ps2_data[0] |=
  			((p->buttons & 0x10) >> 3) | ((p->buttons & 0x08) >> 1);
  		p->dz = 0;
  		client->bufsiz = 3;
  		break;
  	}
  
  	if (!p->dx && !p->dy && !p->dz) {
  		if (client->tail == client->head) {
  			client->ready = 0;
  			client->last_buttons = p->buttons;
  		} else
  			client->tail = (client->tail + 1) % PACKET_QUEUE_LEN;
  	}
  }
  
  static void mousedev_generate_response(struct mousedev_client *client,
  					int command)
  {
  	client->ps2[0] = 0xfa; /* ACK */
  
  	switch (command) {
  
  	case 0xeb: /* Poll */
  		mousedev_packet(client, &client->ps2[1]);
  		client->bufsiz++; /* account for leading ACK */
  		break;
  
  	case 0xf2: /* Get ID */
  		switch (client->mode) {
  		case MOUSEDEV_EMUL_PS2:
  			client->ps2[1] = 0;
  			break;
  		case MOUSEDEV_EMUL_IMPS:
  			client->ps2[1] = 3;
  			break;
  		case MOUSEDEV_EMUL_EXPS:
  			client->ps2[1] = 4;
  			break;
  		}
  		client->bufsiz = 2;
  		break;
  
  	case 0xe9: /* Get info */
  		client->ps2[1] = 0x60; client->ps2[2] = 3; client->ps2[3] = 200;
  		client->bufsiz = 4;
  		break;
  
  	case 0xff: /* Reset */
  		client->impsseq = client->imexseq = 0;
  		client->mode = MOUSEDEV_EMUL_PS2;
  		client->ps2[1] = 0xaa; client->ps2[2] = 0x00;
  		client->bufsiz = 3;
  		break;
  
  	default:
  		client->bufsiz = 1;
  		break;
  	}
  	client->buffer = client->bufsiz;
  }
  
  static ssize_t mousedev_write(struct file *file, const char __user *buffer,
  				size_t count, loff_t *ppos)
  {
  	struct mousedev_client *client = file->private_data;
  	unsigned char c;
  	unsigned int i;
  
  	for (i = 0; i < count; i++) {
  
  		if (get_user(c, buffer + i))
  			return -EFAULT;
  
  		spin_lock_irq(&client->packet_lock);
  
  		if (c == mousedev_imex_seq[client->imexseq]) {
  			if (++client->imexseq == MOUSEDEV_SEQ_LEN) {
  				client->imexseq = 0;
  				client->mode = MOUSEDEV_EMUL_EXPS;
  			}
  		} else
  			client->imexseq = 0;
  
  		if (c == mousedev_imps_seq[client->impsseq]) {
  			if (++client->impsseq == MOUSEDEV_SEQ_LEN) {
  				client->impsseq = 0;
  				client->mode = MOUSEDEV_EMUL_IMPS;
  			}
  		} else
  			client->impsseq = 0;
  
  		mousedev_generate_response(client, c);
  
  		spin_unlock_irq(&client->packet_lock);
  	}
  
  	kill_fasync(&client->fasync, SIGIO, POLL_IN);
  	wake_up_interruptible(&client->mousedev->wait);
  
  	return count;
  }
  
  static ssize_t mousedev_read(struct file *file, char __user *buffer,
  			     size_t count, loff_t *ppos)
  {
  	struct mousedev_client *client = file->private_data;
  	struct mousedev *mousedev = client->mousedev;
  	signed char data[sizeof(client->ps2)];
  	int retval = 0;
  
  	if (!client->ready && !client->buffer && mousedev->exist &&
  	    (file->f_flags & O_NONBLOCK))
  		return -EAGAIN;
  
  	retval = wait_event_interruptible(mousedev->wait,
  			!mousedev->exist || client->ready || client->buffer);
  	if (retval)
  		return retval;
  
  	if (!mousedev->exist)
  		return -ENODEV;
  
  	spin_lock_irq(&client->packet_lock);
  
  	if (!client->buffer && client->ready) {
  		mousedev_packet(client, client->ps2);
  		client->buffer = client->bufsiz;
  	}
  
  	if (count > client->buffer)
  		count = client->buffer;
  
  	memcpy(data, client->ps2 + client->bufsiz - client->buffer, count);
  	client->buffer -= count;
  
  	spin_unlock_irq(&client->packet_lock);
  
  	if (copy_to_user(buffer, data, count))
  		return -EFAULT;
  
  	return count;
  }
  
  /* No kernel lock - fine */
  static unsigned int mousedev_poll(struct file *file, poll_table *wait)
  {
  	struct mousedev_client *client = file->private_data;
  	struct mousedev *mousedev = client->mousedev;
  	unsigned int mask;
  
  	poll_wait(file, &mousedev->wait, wait);
  
  	mask = mousedev->exist ? POLLOUT | POLLWRNORM : POLLHUP | POLLERR;
  	if (client->ready || client->buffer)
  		mask |= POLLIN | POLLRDNORM;
  
  	return mask;
  }
  
  static const struct file_operations mousedev_fops = {
  	.owner		= THIS_MODULE,
  	.read		= mousedev_read,
  	.write		= mousedev_write,
  	.poll		= mousedev_poll,
  	.open		= mousedev_open,
  	.release	= mousedev_release,
  	.fasync		= mousedev_fasync,
  	.llseek		= noop_llseek,
  };
  
  /*
   * Mark device non-existent. This disables writes, ioctls and
   * prevents new users from opening the device. Already posted
   * blocking reads will stay, however new ones will fail.
   */
  static void mousedev_mark_dead(struct mousedev *mousedev)
  {
  	mutex_lock(&mousedev->mutex);
  	mousedev->exist = false;
  	mutex_unlock(&mousedev->mutex);
  }
  
  /*
   * Wake up users waiting for IO so they can disconnect from
   * dead device.
   */
  static void mousedev_hangup(struct mousedev *mousedev)
  {
  	struct mousedev_client *client;
  
  	spin_lock(&mousedev->client_lock);
  	list_for_each_entry(client, &mousedev->client_list, node)
  		kill_fasync(&client->fasync, SIGIO, POLL_HUP);
  	spin_unlock(&mousedev->client_lock);
  
  	wake_up_interruptible(&mousedev->wait);
  }
  
  static void mousedev_cleanup(struct mousedev *mousedev)
  {
  	struct input_handle *handle = &mousedev->handle;
  
  	mousedev_mark_dead(mousedev);
  	mousedev_hangup(mousedev);
  
  	cdev_del(&mousedev->cdev);
  
  	/* mousedev is marked dead so no one else accesses mousedev->open */
  	if (mousedev->open)
  		input_close_device(handle);
  }
  
  static int mousedev_reserve_minor(bool mixdev)
  {
  	int minor;
  
  	if (mixdev) {
  		minor = input_get_new_minor(MOUSEDEV_MIX, 1, false);
  		if (minor < 0)
  			pr_err("failed to reserve mixdev minor: %d
  ", minor);
  	} else {
  		minor = input_get_new_minor(MOUSEDEV_MINOR_BASE,
  					    MOUSEDEV_MINORS, true);
  		if (minor < 0)
  			pr_err("failed to reserve new minor: %d
  ", minor);
  	}
  
  	return minor;
  }
  
  static struct mousedev *mousedev_create(struct input_dev *dev,
  					struct input_handler *handler,
  					bool mixdev)
  {
  	struct mousedev *mousedev;
  	int minor;
  	int error;
  
  	minor = mousedev_reserve_minor(mixdev);
  	if (minor < 0) {
  		error = minor;
  		goto err_out;
  	}
  
  	mousedev = kzalloc(sizeof(struct mousedev), GFP_KERNEL);
  	if (!mousedev) {
  		error = -ENOMEM;
  		goto err_free_minor;
  	}
  
  	INIT_LIST_HEAD(&mousedev->client_list);
  	INIT_LIST_HEAD(&mousedev->mixdev_node);
  	spin_lock_init(&mousedev->client_lock);
  	mutex_init(&mousedev->mutex);
  	lockdep_set_subclass(&mousedev->mutex,
  			     mixdev ? SINGLE_DEPTH_NESTING : 0);
  	init_waitqueue_head(&mousedev->wait);
  
  	if (mixdev) {
  		dev_set_name(&mousedev->dev, "mice");
  
  		mousedev->open_device = mixdev_open_devices;
  		mousedev->close_device = mixdev_close_devices;
  	} else {
  		int dev_no = minor;
  		/* Normalize device number if it falls into legacy range */
  		if (dev_no < MOUSEDEV_MINOR_BASE + MOUSEDEV_MINORS)
  			dev_no -= MOUSEDEV_MINOR_BASE;
  		dev_set_name(&mousedev->dev, "mouse%d", dev_no);
  
  		mousedev->open_device = mousedev_open_device;
  		mousedev->close_device = mousedev_close_device;
  	}
  
  	mousedev->exist = true;
  	mousedev->handle.dev = input_get_device(dev);
  	mousedev->handle.name = dev_name(&mousedev->dev);
  	mousedev->handle.handler = handler;
  	mousedev->handle.private = mousedev;
  
  	mousedev->dev.class = &input_class;
  	if (dev)
  		mousedev->dev.parent = &dev->dev;
  	mousedev->dev.devt = MKDEV(INPUT_MAJOR, minor);
  	mousedev->dev.release = mousedev_free;
  	device_initialize(&mousedev->dev);
  
  	if (!mixdev) {
  		error = input_register_handle(&mousedev->handle);
  		if (error)
  			goto err_free_mousedev;
  	}
  
  	cdev_init(&mousedev->cdev, &mousedev_fops);
  	mousedev->cdev.kobj.parent = &mousedev->dev.kobj;
  	error = cdev_add(&mousedev->cdev, mousedev->dev.devt, 1);
  	if (error)
  		goto err_unregister_handle;
  
  	error = device_add(&mousedev->dev);
  	if (error)
  		goto err_cleanup_mousedev;
  
  	return mousedev;
  
   err_cleanup_mousedev:
  	mousedev_cleanup(mousedev);
   err_unregister_handle:
  	if (!mixdev)
  		input_unregister_handle(&mousedev->handle);
   err_free_mousedev:
  	put_device(&mousedev->dev);
   err_free_minor:
  	input_free_minor(minor);
   err_out:
  	return ERR_PTR(error);
  }
  
  static void mousedev_destroy(struct mousedev *mousedev)
  {
  	device_del(&mousedev->dev);
  	mousedev_cleanup(mousedev);
  	input_free_minor(MINOR(mousedev->dev.devt));
  	if (mousedev != mousedev_mix)
  		input_unregister_handle(&mousedev->handle);
  	put_device(&mousedev->dev);
  }
  
  static int mixdev_add_device(struct mousedev *mousedev)
  {
  	int retval;
  
  	retval = mutex_lock_interruptible(&mousedev_mix->mutex);
  	if (retval)
  		return retval;
  
  	if (mousedev_mix->open) {
  		retval = mousedev_open_device(mousedev);
  		if (retval)
  			goto out;
  
  		mousedev->opened_by_mixdev = true;
  	}
  
  	get_device(&mousedev->dev);
  	list_add_tail(&mousedev->mixdev_node, &mousedev_mix_list);
  
   out:
  	mutex_unlock(&mousedev_mix->mutex);
  	return retval;
  }
  
  static void mixdev_remove_device(struct mousedev *mousedev)
  {
  	mutex_lock(&mousedev_mix->mutex);
  
  	if (mousedev->opened_by_mixdev) {
  		mousedev->opened_by_mixdev = false;
  		mousedev_close_device(mousedev);
  	}
  
  	list_del_init(&mousedev->mixdev_node);
  	mutex_unlock(&mousedev_mix->mutex);
  
  	put_device(&mousedev->dev);
  }
  
  static int mousedev_connect(struct input_handler *handler,
  			    struct input_dev *dev,
  			    const struct input_device_id *id)
  {
  	struct mousedev *mousedev;
  	int error;
  
  	mousedev = mousedev_create(dev, handler, false);
  	if (IS_ERR(mousedev))
  		return PTR_ERR(mousedev);
  
  	error = mixdev_add_device(mousedev);
  	if (error) {
  		mousedev_destroy(mousedev);
  		return error;
  	}
  
  	return 0;
  }
  
  static void mousedev_disconnect(struct input_handle *handle)
  {
  	struct mousedev *mousedev = handle->private;
  
  	mixdev_remove_device(mousedev);
  	mousedev_destroy(mousedev);
  }
  
  static const struct input_device_id mousedev_ids[] = {
  	{
  		.flags = INPUT_DEVICE_ID_MATCH_EVBIT |
  				INPUT_DEVICE_ID_MATCH_KEYBIT |
  				INPUT_DEVICE_ID_MATCH_RELBIT,
  		.evbit = { BIT_MASK(EV_KEY) | BIT_MASK(EV_REL) },
  		.keybit = { [BIT_WORD(BTN_LEFT)] = BIT_MASK(BTN_LEFT) },
  		.relbit = { BIT_MASK(REL_X) | BIT_MASK(REL_Y) },
  	},	/* A mouse like device, at least one button,
  		   two relative axes */
  	{
  		.flags = INPUT_DEVICE_ID_MATCH_EVBIT |
  				INPUT_DEVICE_ID_MATCH_RELBIT,
  		.evbit = { BIT_MASK(EV_KEY) | BIT_MASK(EV_REL) },
  		.relbit = { BIT_MASK(REL_WHEEL) },
  	},	/* A separate scrollwheel */
  	{
  		.flags = INPUT_DEVICE_ID_MATCH_EVBIT |
  				INPUT_DEVICE_ID_MATCH_KEYBIT |
  				INPUT_DEVICE_ID_MATCH_ABSBIT,
  		.evbit = { BIT_MASK(EV_KEY) | BIT_MASK(EV_ABS) },
  		.keybit = { [BIT_WORD(BTN_TOUCH)] = BIT_MASK(BTN_TOUCH) },
  		.absbit = { BIT_MASK(ABS_X) | BIT_MASK(ABS_Y) },
  	},	/* A tablet like device, at least touch detection,
  		   two absolute axes */
  	{
  		.flags = INPUT_DEVICE_ID_MATCH_EVBIT |
  				INPUT_DEVICE_ID_MATCH_KEYBIT |
  				INPUT_DEVICE_ID_MATCH_ABSBIT,
  		.evbit = { BIT_MASK(EV_KEY) | BIT_MASK(EV_ABS) },
  		.keybit = { [BIT_WORD(BTN_TOOL_FINGER)] =
  				BIT_MASK(BTN_TOOL_FINGER) },
  		.absbit = { BIT_MASK(ABS_X) | BIT_MASK(ABS_Y) |
  				BIT_MASK(ABS_PRESSURE) |
  				BIT_MASK(ABS_TOOL_WIDTH) },
  	},	/* A touchpad */
  	{
  		.flags = INPUT_DEVICE_ID_MATCH_EVBIT |
  			INPUT_DEVICE_ID_MATCH_KEYBIT |
  			INPUT_DEVICE_ID_MATCH_ABSBIT,
  		.evbit = { BIT_MASK(EV_KEY) | BIT_MASK(EV_ABS) },
  		.keybit = { [BIT_WORD(BTN_LEFT)] = BIT_MASK(BTN_LEFT) },
  		.absbit = { BIT_MASK(ABS_X) | BIT_MASK(ABS_Y) },
  	},	/* Mouse-like device with absolute X and Y but ordinary
  		   clicks, like hp ILO2 High Performance mouse */
  
  	{ },	/* Terminating entry */
  };
  
  MODULE_DEVICE_TABLE(input, mousedev_ids);
  
  static struct input_handler mousedev_handler = {
  	.event		= mousedev_event,
  	.connect	= mousedev_connect,
  	.disconnect	= mousedev_disconnect,
  	.legacy_minors	= true,
  	.minor		= MOUSEDEV_MINOR_BASE,
  	.name		= "mousedev",
  	.id_table	= mousedev_ids,
  };
  
  #ifdef CONFIG_INPUT_MOUSEDEV_PSAUX
  #include <linux/miscdevice.h>
  
  static struct miscdevice psaux_mouse = {
  	.minor	= PSMOUSE_MINOR,
  	.name	= "psaux",
  	.fops	= &mousedev_fops,
  };
  
  static bool psaux_registered;
  
  static void __init mousedev_psaux_register(void)
  {
  	int error;
  
  	error = misc_register(&psaux_mouse);
  	if (error)
  		pr_warn("could not register psaux device, error: %d
  ",
  			   error);
  	else
  		psaux_registered = true;
  }
  
  static void __exit mousedev_psaux_unregister(void)
  {
  	if (psaux_registered)
  		misc_deregister(&psaux_mouse);
  }
  #else
  static inline void mousedev_psaux_register(void) { }
  static inline void mousedev_psaux_unregister(void) { }
  #endif
  
  static int __init mousedev_init(void)
  {
  	int error;
  
  	mousedev_mix = mousedev_create(NULL, &mousedev_handler, true);
  	if (IS_ERR(mousedev_mix))
  		return PTR_ERR(mousedev_mix);
  
  	error = input_register_handler(&mousedev_handler);
  	if (error) {
  		mousedev_destroy(mousedev_mix);
  		return error;
  	}
  
  	mousedev_psaux_register();
  
  	pr_info("PS/2 mouse device common for all mice
  ");
  
  	return 0;
  }
  
  static void __exit mousedev_exit(void)
  {
  	mousedev_psaux_unregister();
  	input_unregister_handler(&mousedev_handler);
  	mousedev_destroy(mousedev_mix);
  }
  
  module_init(mousedev_init);
  module_exit(mousedev_exit);