joydev.c

来自「linux 内核源代码」· C语言 代码 · 共 900 行 · 第 1/2 页

/*
 * Joystick device driver for the input driver suite.
 *
 * Copyright (c) 1999-2002 Vojtech Pavlik
 * Copyright (c) 1999 Colin Van Dyke
 *
 * 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; either version 2 of the License, or
 * (at your option) any later version.
 */

#include <asm/io.h>
#include <asm/system.h>
#include <linux/delay.h>
#include <linux/errno.h>
#include <linux/joystick.h>
#include <linux/input.h>
#include <linux/kernel.h>
#include <linux/major.h>
#include <linux/slab.h>
#include <linux/mm.h>
#include <linux/miscdevice.h>
#include <linux/module.h>
#include <linux/poll.h>
#include <linux/init.h>
#include <linux/device.h>

MODULE_AUTHOR("Vojtech Pavlik <[e-mail]>");
MODULE_DESCRIPTION("Joystick device interfaces");
MODULE_SUPPORTED_DEVICE("input/js");
MODULE_LICENSE("GPL");

#define JOYDEV_MINOR_BASE	0
#define JOYDEV_MINORS		16
#define JOYDEV_BUFFER_SIZE	64

struct joydev {
	int exist;
	int open;
	int minor;
	char name[16];
	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 js_corr corr[ABS_MAX + 1];
	struct JS_DATA_SAVE_TYPE glue;
	int nabs;
	int nkey;
	__u16 keymap[KEY_MAX - BTN_MISC + 1];
	__u16 keypam[KEY_MAX - BTN_MISC + 1];
	__u8 absmap[ABS_MAX + 1];
	__u8 abspam[ABS_MAX + 1];
	__s16 abs[ABS_MAX + 1];
};

struct joydev_client {
	struct js_event buffer[JOYDEV_BUFFER_SIZE];
	int head;
	int tail;
	int startup;
	spinlock_t buffer_lock; /* protects access to buffer, head and tail */
	struct fasync_struct *fasync;
	struct joydev *joydev;
	struct list_head node;
};

static struct joydev *joydev_table[JOYDEV_MINORS];
static DEFINE_MUTEX(joydev_table_mutex);

static int joydev_correct(int value, struct js_corr *corr)
{
	switch (corr->type) {

	case JS_CORR_NONE:
		break;

	case JS_CORR_BROKEN:
		value = value > corr->coef[0] ? (value < corr->coef[1] ? 0 :
			((corr->coef[3] * (value - corr->coef[1])) >> 14)) :
			((corr->coef[2] * (value - corr->coef[0])) >> 14);
		break;

	default:
		return 0;
	}

	return value < -32767 ? -32767 : (value > 32767 ? 32767 : value);
}

static void joydev_pass_event(struct joydev_client *client,
			      struct js_event *event)
{
	struct joydev *joydev = client->joydev;

	/*
	 * IRQs already disabled, just acquire the lock
	 */
	spin_lock(&client->buffer_lock);

	client->buffer[client->head] = *event;

	if (client->startup == joydev->nabs + joydev->nkey) {
		client->head++;
		client->head &= JOYDEV_BUFFER_SIZE - 1;
		if (client->tail == client->head)
			client->startup = 0;
	}

	spin_unlock(&client->buffer_lock);

	kill_fasync(&client->fasync, SIGIO, POLL_IN);
}

static void joydev_event(struct input_handle *handle,
			 unsigned int type, unsigned int code, int value)
{
	struct joydev *joydev = handle->private;
	struct joydev_client *client;
	struct js_event event;

	switch (type) {

	case EV_KEY:
		if (code < BTN_MISC || value == 2)
			return;
		event.type = JS_EVENT_BUTTON;
		event.number = joydev->keymap[code - BTN_MISC];
		event.value = value;
		break;

	case EV_ABS:
		event.type = JS_EVENT_AXIS;
		event.number = joydev->absmap[code];
		event.value = joydev_correct(value,
					&joydev->corr[event.number]);
		if (event.value == joydev->abs[event.number])
			return;
		joydev->abs[event.number] = event.value;
		break;

	default:
		return;
	}

	event.time = jiffies_to_msecs(jiffies);

	rcu_read_lock();
	list_for_each_entry_rcu(client, &joydev->client_list, node)
		joydev_pass_event(client, &event);
	rcu_read_unlock();

	wake_up_interruptible(&joydev->wait);
}

static int joydev_fasync(int fd, struct file *file, int on)
{
	int retval;
	struct joydev_client *client = file->private_data;

	retval = fasync_helper(fd, file, on, &client->fasync);

	return retval < 0 ? retval : 0;
}

static void joydev_free(struct device *dev)
{
	struct joydev *joydev = container_of(dev, struct joydev, dev);

	kfree(joydev);
}

static void joydev_attach_client(struct joydev *joydev,
				 struct joydev_client *client)
{
	spin_lock(&joydev->client_lock);
	list_add_tail_rcu(&client->node, &joydev->client_list);
	spin_unlock(&joydev->client_lock);
	synchronize_rcu();
}

static void joydev_detach_client(struct joydev *joydev,
				 struct joydev_client *client)
{
	spin_lock(&joydev->client_lock);
	list_del_rcu(&client->node);
	spin_unlock(&joydev->client_lock);
	synchronize_rcu();
}

static int joydev_open_device(struct joydev *joydev)
{
	int retval;

	retval = mutex_lock_interruptible(&joydev->mutex);
	if (retval)
		return retval;

	if (!joydev->exist)
		retval = -ENODEV;
	else if (!joydev->open++) {
		retval = input_open_device(&joydev->handle);
		if (retval)
			joydev->open--;
	}

	mutex_unlock(&joydev->mutex);
	return retval;
}

static void joydev_close_device(struct joydev *joydev)
{
	mutex_lock(&joydev->mutex);

	if (joydev->exist && !--joydev->open)
		input_close_device(&joydev->handle);

	mutex_unlock(&joydev->mutex);
}

/*
 * Wake up users waiting for IO so they can disconnect from
 * dead device.
 */
static void joydev_hangup(struct joydev *joydev)
{
	struct joydev_client *client;

	spin_lock(&joydev->client_lock);
	list_for_each_entry(client, &joydev->client_list, node)
		kill_fasync(&client->fasync, SIGIO, POLL_HUP);
	spin_unlock(&joydev->client_lock);

	wake_up_interruptible(&joydev->wait);
}

static int joydev_release(struct inode *inode, struct file *file)
{
	struct joydev_client *client = file->private_data;
	struct joydev *joydev = client->joydev;

	joydev_fasync(-1, file, 0);
	joydev_detach_client(joydev, client);
	kfree(client);

	joydev_close_device(joydev);
	put_device(&joydev->dev);

	return 0;
}

static int joydev_open(struct inode *inode, struct file *file)
{
	struct joydev_client *client;
	struct joydev *joydev;
	int i = iminor(inode) - JOYDEV_MINOR_BASE;
	int error;

	if (i >= JOYDEV_MINORS)
		return -ENODEV;

	error = mutex_lock_interruptible(&joydev_table_mutex);
	if (error)
		return error;
	joydev = joydev_table[i];
	if (joydev)
		get_device(&joydev->dev);
	mutex_unlock(&joydev_table_mutex);

	if (!joydev)
		return -ENODEV;

	client = kzalloc(sizeof(struct joydev_client), GFP_KERNEL);
	if (!client) {
		error = -ENOMEM;
		goto err_put_joydev;
	}

	spin_lock_init(&client->buffer_lock);
	client->joydev = joydev;
	joydev_attach_client(joydev, client);

	error = joydev_open_device(joydev);
	if (error)
		goto err_free_client;

	file->private_data = client;
	return 0;

 err_free_client:
	joydev_detach_client(joydev, client);
	kfree(client);
 err_put_joydev:
	put_device(&joydev->dev);
	return error;
}

static int joydev_generate_startup_event(struct joydev_client *client,
					 struct input_dev *input,
					 struct js_event *event)
{
	struct joydev *joydev = client->joydev;
	int have_event;

	spin_lock_irq(&client->buffer_lock);

	have_event = client->startup < joydev->nabs + joydev->nkey;

	if (have_event) {

		event->time = jiffies_to_msecs(jiffies);
		if (client->startup < joydev->nkey) {
			event->type = JS_EVENT_BUTTON | JS_EVENT_INIT;
			event->number = client->startup;
			event->value = !!test_bit(joydev->keypam[event->number],
						  input->key);
		} else {
			event->type = JS_EVENT_AXIS | JS_EVENT_INIT;
			event->number = client->startup - joydev->nkey;
			event->value = joydev->abs[event->number];
		}
		client->startup++;
	}

	spin_unlock_irq(&client->buffer_lock);

	return have_event;
}

static int joydev_fetch_next_event(struct joydev_client *client,
				   struct js_event *event)
{
	int have_event;

	spin_lock_irq(&client->buffer_lock);

	have_event = client->head != client->tail;
	if (have_event) {
		*event = client->buffer[client->tail++];
		client->tail &= JOYDEV_BUFFER_SIZE - 1;
	}

	spin_unlock_irq(&client->buffer_lock);

	return have_event;
}

/*
 * Old joystick interface
 */
static ssize_t joydev_0x_read(struct joydev_client *client,
			      struct input_dev *input,
			      char __user *buf)
{
	struct joydev *joydev = client->joydev;
	struct JS_DATA_TYPE data;
	int i;

	spin_lock_irq(&input->event_lock);

	/*
	 * Get device state
	 */
	for (data.buttons = i = 0; i < 32 && i < joydev->nkey; i++)
		data.buttons |=
			test_bit(joydev->keypam[i], input->key) ? (1 << i) : 0;
	data.x = (joydev->abs[0] / 256 + 128) >> joydev->glue.JS_CORR.x;
	data.y = (joydev->abs[1] / 256 + 128) >> joydev->glue.JS_CORR.y;

	/*
	 * Reset reader's event queue
	 */
	spin_lock(&client->buffer_lock);
	client->startup = 0;
	client->tail = client->head;
	spin_unlock(&client->buffer_lock);

	spin_unlock_irq(&input->event_lock);

	if (copy_to_user(buf, &data, sizeof(struct JS_DATA_TYPE)))
		return -EFAULT;

	return sizeof(struct JS_DATA_TYPE);
}

static inline int joydev_data_pending(struct joydev_client *client)
{
	struct joydev *joydev = client->joydev;

	return client->startup < joydev->nabs + joydev->nkey ||
		client->head != client->tail;
}

static ssize_t joydev_read(struct file *file, char __user *buf,
			   size_t count, loff_t *ppos)
{
	struct joydev_client *client = file->private_data;
	struct joydev *joydev = client->joydev;
	struct input_dev *input = joydev->handle.dev;
	struct js_event event;
	int retval;

	if (!joydev->exist)
		return -ENODEV;

	if (count < sizeof(struct js_event))
		return -EINVAL;

	if (count == sizeof(struct JS_DATA_TYPE))
		return joydev_0x_read(client, input, buf);

	if (!joydev_data_pending(client) && (file->f_flags & O_NONBLOCK))
		return -EAGAIN;

	retval = wait_event_interruptible(joydev->wait,
			!joydev->exist || joydev_data_pending(client));
	if (retval)
		return retval;

	if (!joydev->exist)
		return -ENODEV;

	while (retval + sizeof(struct js_event) <= count &&
	       joydev_generate_startup_event(client, input, &event)) {

		if (copy_to_user(buf + retval, &event, sizeof(struct js_event)))
			return -EFAULT;

		retval += sizeof(struct js_event);
	}

	while (retval + sizeof(struct js_event) <= count &&
	       joydev_fetch_next_event(client, &event)) {

		if (copy_to_user(buf + retval, &event, sizeof(struct js_event)))
			return -EFAULT;

		retval += sizeof(struct js_event);
	}

	return retval;
}

/* No kernel lock - fine */
static unsigned int joydev_poll(struct file *file, poll_table *wait)
{