path: root/drivers/gpu/vga/vgaarb.c

/*
 * vgaarb.c: Implements the VGA arbitration. For details refer to
 * Documentation/vgaarbiter.txt
 *
 *
 * (C) Copyright 2005 Benjamin Herrenschmidt <benh@kernel.crashing.org>
 * (C) Copyright 2007 Paulo R. Zanoni <przanoni@gmail.com>
 * (C) Copyright 2007, 2009 Tiago Vignatti <vignatti@freedesktop.org>
 *
 * Permission is hereby granted, free of charge, to any person obtaining a
 * copy of this software and associated documentation files (the "Software"),
 * to deal in the Software without restriction, including without limitation
 * the rights to use, copy, modify, merge, publish, distribute, sublicense,
 * and/or sell copies of the Software, and to permit persons to whom the
 * Software is furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice (including the next
 * paragraph) shall be included in all copies or substantial portions of the
 * Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
 * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
 * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
 * DEALINGS
 * IN THE SOFTWARE.
 *
 */

#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/pci.h>
#include <linux/errno.h>
#include <linux/init.h>
#include <linux/list.h>
#include <linux/sched.h>
#include <linux/wait.h>
#include <linux/spinlock.h>
#include <linux/poll.h>
#include <linux/miscdevice.h>
#include <linux/slab.h>

#include <linux/uaccess.h>

#include <linux/vgaarb.h>

static void vga_arbiter_notify_clients(void);
/*
 * We keep a list of all vga devices in the system to speed
 * up the various operations of the arbiter
 */
struct vga_device {
	struct list_head list;
	struct pci_dev *pdev;
	unsigned int decodes;	/* what does it decodes */
	unsigned int owns;	/* what does it owns */
	unsigned int locks;	/* what does it locks */
	unsigned int io_lock_cnt;	/* legacy IO lock count */
	unsigned int mem_lock_cnt;	/* legacy MEM lock count */
	unsigned int io_norm_cnt;	/* normal IO count */
	unsigned int mem_norm_cnt;	/* normal MEM count */

	/* allow IRQ enable/disable hook */
	void *cookie;
	void (*irq_set_state)(void *cookie, bool enable);
	unsigned int (*set_vga_decode)(void *cookie, bool decode);
};

static LIST_HEAD(vga_list);
static int vga_count, vga_decode_count;
static bool vga_arbiter_used;
static DEFINE_SPINLOCK(vga_lock);
static DECLARE_WAIT_QUEUE_HEAD(vga_wait_queue);


static const char *vga_iostate_to_str(unsigned int iostate)
{
	/* Ignore VGA_RSRC_IO and VGA_RSRC_MEM */
	iostate &= VGA_RSRC_LEGACY_IO | VGA_RSRC_LEGACY_MEM;
	switch (iostate) {
	case VGA_RSRC_LEGACY_IO | VGA_RSRC_LEGACY_MEM:
		return "io+mem";
	case VGA_RSRC_LEGACY_IO:
		return "io";
	case VGA_RSRC_LEGACY_MEM:
		return "mem";
	}
	return "none";
}

static int vga_str_to_iostate(char *buf, int str_size, int *io_state)
{
	/* we could in theory hand out locks on IO and mem
	 * separately to userspace but it can cause deadlocks */
	if (strncmp(buf, "none", 4) == 0) {
		*io_state = VGA_RSRC_NONE;
		return 1;
	}

	/* XXX We're not chekcing the str_size! */
	if (strncmp(buf, "io+mem", 6) == 0)
		goto both;
	else if (strncmp(buf, "io", 2) == 0)
		goto both;
	else if (strncmp(buf