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vgaarb.c
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vgaarb.c
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// SPDX-License-Identifier: MIT
/*
* vgaarb.c: Implements the VGA arbitration. For details refer to
* Documentation/gpu/vgaarbiter.rst
*
* (C) Copyright 2005 Benjamin Herrenschmidt <[email protected]>
* (C) Copyright 2007 Paulo R. Zanoni <[email protected]>
* (C) Copyright 2007, 2009 Tiago Vignatti <[email protected]>
*/
#define pr_fmt(fmt) "vgaarb: " fmt
#define vgaarb_dbg(dev, fmt, arg...) dev_dbg(dev, "vgaarb: " fmt, ##arg)
#define vgaarb_info(dev, fmt, arg...) dev_info(dev, "vgaarb: " fmt, ##arg)
#define vgaarb_err(dev, fmt, arg...) dev_err(dev, "vgaarb: " fmt, ##arg)
#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/signal.h>
#include <linux/wait.h>
#include <linux/spinlock.h>
#include <linux/poll.h>
#include <linux/miscdevice.h>
#include <linux/slab.h>
#include <linux/screen_info.h>
#include <linux/vt.h>
#include <linux/console.h>
#include <linux/acpi.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 */
bool bridge_has_one_vga;
bool is_firmware_default; /* device selected by firmware */
unsigned int (*set_decode)(struct pci_dev *pdev, 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, "mem", 3) == 0)
goto both;
return 0;
both:
*io_state = VGA_RSRC_LEGACY_IO | VGA_RSRC_LEGACY_MEM;
return 1;
}
/* this is only used a cookie - it should not be dereferenced */
static struct pci_dev *vga_default;
/* Find somebody in our list */
static struct vga_device *vgadev_find(struct pci_dev *pdev)
{
struct vga_device *vgadev;
list_for_each_entry(vgadev, &vga_list, list)
if (pdev == vgadev->pdev)
return vgadev;
return NULL;
}
/**
* vga_default_device - return the default VGA device, for vgacon
*
* This can be defined by the platform. The default implementation
* is rather dumb and will probably only work properly on single
* vga card setups and/or x86 platforms.
*
* If your VGA default device is not PCI, you'll have to return
* NULL here. In this case, I assume it will not conflict with
* any PCI card. If this is not true, I'll have to define two archs
* hooks for enabling/disabling the VGA default device if that is
* possible. This may be a problem with real _ISA_ VGA cards, in
* addition to a PCI one. I don't know at this point how to deal
* with that card. Can theirs IOs be disabled at all ? If not, then
* I suppose it's a matter of having the proper arch hook telling
* us about it, so we basically never allow anybody to succeed a
* vga_get()...
*/
struct pci_dev *vga_default_device(void)
{
return vga_default;
}
EXPORT_SYMBOL_GPL(vga_default_device);
void vga_set_default_device(struct pci_dev *pdev)
{
if (vga_default == pdev)
return;
pci_dev_put(vga_default);
vga_default = pci_dev_get(pdev);
}
/**
* vga_remove_vgacon - deactivete vga console
*
* Unbind and unregister vgacon in case pdev is the default vga
* device. Can be called by gpu drivers on initialization to make
* sure vga register access done by vgacon will not disturb the
* device.
*
* @pdev: pci device.
*/
#if !defined(CONFIG_VGA_CONSOLE)
int vga_remove_vgacon(struct pci_dev *pdev)
{
return 0;
}
#elif !defined(CONFIG_DUMMY_CONSOLE)
int vga_remove_vgacon(struct pci_dev *pdev)
{
return -ENODEV;
}
#else
int vga_remove_vgacon(struct pci_dev *pdev)
{
int ret = 0;
if (pdev != vga_default)
return 0;
vgaarb_info(&pdev->dev, "deactivate vga console\n");
console_lock();
if (con_is_bound(&vga_con))
ret = do_take_over_console(&dummy_con, 0,
MAX_NR_CONSOLES - 1, 1);
if (ret == 0) {
ret = do_unregister_con_driver(&vga_con);
/* Ignore "already unregistered". */
if (ret == -ENODEV)
ret = 0;
}
console_unlock();
return ret;
}
#endif
EXPORT_SYMBOL(vga_remove_vgacon);
/* If we don't ever use VGA arb we should avoid
turning off anything anywhere due to old X servers getting
confused about the boot device not being VGA */
static void vga_check_first_use(void)
{
/* we should inform all GPUs in the system that
* VGA arb has occurred and to try and disable resources
* if they can */
if (!vga_arbiter_used) {
vga_arbiter_used = true;
vga_arbiter_notify_clients();
}
}
static struct vga_device *__vga_tryget(struct vga_device *vgadev,
unsigned int rsrc)
{
struct device *dev = &vgadev->pdev->dev;
unsigned int wants, legacy_wants, match;
struct vga_device *conflict;
unsigned int pci_bits;
u32 flags = 0;
/* Account for "normal" resources to lock. If we decode the legacy,
* counterpart, we need to request it as well
*/
if ((rsrc & VGA_RSRC_NORMAL_IO) &&
(vgadev->decodes & VGA_RSRC_LEGACY_IO))
rsrc |= VGA_RSRC_LEGACY_IO;
if ((rsrc & VGA_RSRC_NORMAL_MEM) &&
(vgadev->decodes & VGA_RSRC_LEGACY_MEM))
rsrc |= VGA_RSRC_LEGACY_MEM;
vgaarb_dbg(dev, "%s: %d\n", __func__, rsrc);
vgaarb_dbg(dev, "%s: owns: %d\n", __func__, vgadev->owns);
/* Check what resources we need to acquire */
wants = rsrc & ~vgadev->owns;
/* We already own everything, just mark locked & bye bye */
if (wants == 0)
goto lock_them;
/* We don't need to request a legacy resource, we just enable
* appropriate decoding and go
*/
legacy_wants = wants & VGA_RSRC_LEGACY_MASK;
if (legacy_wants == 0)
goto enable_them;
/* Ok, we don't, let's find out how we need to kick off */
list_for_each_entry(conflict, &vga_list, list) {
unsigned int lwants = legacy_wants;
unsigned int change_bridge = 0;
/* Don't conflict with myself */
if (vgadev == conflict)
continue;
/* We have a possible conflict. before we go further, we must
* check if we sit on the same bus as the conflicting device.
* if we don't, then we must tie both IO and MEM resources
* together since there is only a single bit controlling
* VGA forwarding on P2P bridges
*/
if (vgadev->pdev->bus != conflict->pdev->bus) {
change_bridge = 1;
lwants = VGA_RSRC_LEGACY_IO | VGA_RSRC_LEGACY_MEM;
}
/* Check if the guy has a lock on the resource. If he does,
* return the conflicting entry
*/
if (conflict->locks & lwants)
return conflict;
/* Ok, now check if it owns the resource we want. We can
* lock resources that are not decoded, therefore a device
* can own resources it doesn't decode.
*/
match = lwants & conflict->owns;
if (!match)
continue;
/* looks like he doesn't have a lock, we can steal
* them from him
*/
flags = 0;
pci_bits = 0;
/* If we can't control legacy resources via the bridge, we
* also need to disable normal decoding.
*/
if (!conflict->bridge_has_one_vga) {
if ((match & conflict->decodes) & VGA_RSRC_LEGACY_MEM)
pci_bits |= PCI_COMMAND_MEMORY;
if ((match & conflict->decodes) & VGA_RSRC_LEGACY_IO)
pci_bits |= PCI_COMMAND_IO;
if (pci_bits)
flags |= PCI_VGA_STATE_CHANGE_DECODES;
}
if (change_bridge)
flags |= PCI_VGA_STATE_CHANGE_BRIDGE;
pci_set_vga_state(conflict->pdev, false, pci_bits, flags);
conflict->owns &= ~match;
/* If we disabled normal decoding, reflect it in owns */
if (pci_bits & PCI_COMMAND_MEMORY)
conflict->owns &= ~VGA_RSRC_NORMAL_MEM;
if (pci_bits & PCI_COMMAND_IO)
conflict->owns &= ~VGA_RSRC_NORMAL_IO;
}
enable_them:
/* ok dude, we got it, everybody conflicting has been disabled, let's
* enable us. Mark any bits in "owns" regardless of whether we
* decoded them. We can lock resources we don't decode, therefore
* we must track them via "owns".
*/
flags = 0;
pci_bits = 0;
if (!vgadev->bridge_has_one_vga) {
flags |= PCI_VGA_STATE_CHANGE_DECODES;
if (wants & (VGA_RSRC_LEGACY_MEM|VGA_RSRC_NORMAL_MEM))
pci_bits |= PCI_COMMAND_MEMORY;
if (wants & (VGA_RSRC_LEGACY_IO|VGA_RSRC_NORMAL_IO))
pci_bits |= PCI_COMMAND_IO;
}
if (wants & VGA_RSRC_LEGACY_MASK)
flags |= PCI_VGA_STATE_CHANGE_BRIDGE;
pci_set_vga_state(vgadev->pdev, true, pci_bits, flags);
vgadev->owns |= wants;
lock_them:
vgadev->locks |= (rsrc & VGA_RSRC_LEGACY_MASK);
if (rsrc & VGA_RSRC_LEGACY_IO)
vgadev->io_lock_cnt++;
if (rsrc & VGA_RSRC_LEGACY_MEM)
vgadev->mem_lock_cnt++;
if (rsrc & VGA_RSRC_NORMAL_IO)
vgadev->io_norm_cnt++;
if (rsrc & VGA_RSRC_NORMAL_MEM)
vgadev->mem_norm_cnt++;
return NULL;
}
static void __vga_put(struct vga_device *vgadev, unsigned int rsrc)
{
struct device *dev = &vgadev->pdev->dev;
unsigned int old_locks = vgadev->locks;
vgaarb_dbg(dev, "%s\n", __func__);
/* Update our counters, and account for equivalent legacy resources
* if we decode them
*/
if ((rsrc & VGA_RSRC_NORMAL_IO) && vgadev->io_norm_cnt > 0) {
vgadev->io_norm_cnt--;
if (vgadev->decodes & VGA_RSRC_LEGACY_IO)
rsrc |= VGA_RSRC_LEGACY_IO;
}
if ((rsrc & VGA_RSRC_NORMAL_MEM) && vgadev->mem_norm_cnt > 0) {
vgadev->mem_norm_cnt--;
if (vgadev->decodes & VGA_RSRC_LEGACY_MEM)
rsrc |= VGA_RSRC_LEGACY_MEM;
}
if ((rsrc & VGA_RSRC_LEGACY_IO) && vgadev->io_lock_cnt > 0)
vgadev->io_lock_cnt--;
if ((rsrc & VGA_RSRC_LEGACY_MEM) && vgadev->mem_lock_cnt > 0)
vgadev->mem_lock_cnt--;
/* Just clear lock bits, we do lazy operations so we don't really
* have to bother about anything else at this point
*/
if (vgadev->io_lock_cnt == 0)
vgadev->locks &= ~VGA_RSRC_LEGACY_IO;
if (vgadev->mem_lock_cnt == 0)
vgadev->locks &= ~VGA_RSRC_LEGACY_MEM;
/* Kick the wait queue in case somebody was waiting if we actually
* released something
*/
if (old_locks != vgadev->locks)
wake_up_all(&vga_wait_queue);
}
/**
* vga_get - acquire & locks VGA resources
* @pdev: pci device of the VGA card or NULL for the system default
* @rsrc: bit mask of resources to acquire and lock
* @interruptible: blocking should be interruptible by signals ?
*
* This function acquires VGA resources for the given card and mark those
* resources locked. If the resource requested are "normal" (and not legacy)
* resources, the arbiter will first check whether the card is doing legacy
* decoding for that type of resource. If yes, the lock is "converted" into a
* legacy resource lock.
*
* The arbiter will first look for all VGA cards that might conflict and disable
* their IOs and/or Memory access, including VGA forwarding on P2P bridges if
* necessary, so that the requested resources can be used. Then, the card is
* marked as locking these resources and the IO and/or Memory accesses are
* enabled on the card (including VGA forwarding on parent P2P bridges if any).
*
* This function will block if some conflicting card is already locking one of
* the required resources (or any resource on a different bus segment, since P2P
* bridges don't differentiate VGA memory and IO afaik). You can indicate
* whether this blocking should be interruptible by a signal (for userland
* interface) or not.
*
* Must not be called at interrupt time or in atomic context. If the card
* already owns the resources, the function succeeds. Nested calls are
* supported (a per-resource counter is maintained)
*
* On success, release the VGA resource again with vga_put().
*
* Returns:
*
* 0 on success, negative error code on failure.
*/
int vga_get(struct pci_dev *pdev, unsigned int rsrc, int interruptible)
{
struct vga_device *vgadev, *conflict;
unsigned long flags;
wait_queue_entry_t wait;
int rc = 0;
vga_check_first_use();
/* The one who calls us should check for this, but lets be sure... */
if (pdev == NULL)
pdev = vga_default_device();
if (pdev == NULL)
return 0;
for (;;) {
spin_lock_irqsave(&vga_lock, flags);
vgadev = vgadev_find(pdev);
if (vgadev == NULL) {
spin_unlock_irqrestore(&vga_lock, flags);
rc = -ENODEV;
break;
}
conflict = __vga_tryget(vgadev, rsrc);
spin_unlock_irqrestore(&vga_lock, flags);
if (conflict == NULL)
break;
/* We have a conflict, we wait until somebody kicks the
* work queue. Currently we have one work queue that we
* kick each time some resources are released, but it would
* be fairly easy to have a per device one so that we only
* need to attach to the conflicting device
*/
init_waitqueue_entry(&wait, current);
add_wait_queue(&vga_wait_queue, &wait);
set_current_state(interruptible ?
TASK_INTERRUPTIBLE :
TASK_UNINTERRUPTIBLE);
if (interruptible && signal_pending(current)) {
__set_current_state(TASK_RUNNING);
remove_wait_queue(&vga_wait_queue, &wait);
rc = -ERESTARTSYS;
break;
}
schedule();
remove_wait_queue(&vga_wait_queue, &wait);
}
return rc;
}
EXPORT_SYMBOL(vga_get);
/**
* vga_tryget - try to acquire & lock legacy VGA resources
* @pdev: pci devivce of VGA card or NULL for system default
* @rsrc: bit mask of resources to acquire and lock
*
* This function performs the same operation as vga_get(), but will return an
* error (-EBUSY) instead of blocking if the resources are already locked by
* another card. It can be called in any context
*
* On success, release the VGA resource again with vga_put().
*
* Returns:
*
* 0 on success, negative error code on failure.
*/
static int vga_tryget(struct pci_dev *pdev, unsigned int rsrc)
{
struct vga_device *vgadev;
unsigned long flags;
int rc = 0;
vga_check_first_use();
/* The one who calls us should check for this, but lets be sure... */
if (pdev == NULL)
pdev = vga_default_device();
if (pdev == NULL)
return 0;
spin_lock_irqsave(&vga_lock, flags);
vgadev = vgadev_find(pdev);
if (vgadev == NULL) {
rc = -ENODEV;
goto bail;
}
if (__vga_tryget(vgadev, rsrc))
rc = -EBUSY;
bail:
spin_unlock_irqrestore(&vga_lock, flags);
return rc;
}
/**
* vga_put - release lock on legacy VGA resources
* @pdev: pci device of VGA card or NULL for system default
* @rsrc: but mask of resource to release
*
* This fuction releases resources previously locked by vga_get() or
* vga_tryget(). The resources aren't disabled right away, so that a subsequence
* vga_get() on the same card will succeed immediately. Resources have a
* counter, so locks are only released if the counter reaches 0.
*/
void vga_put(struct pci_dev *pdev, unsigned int rsrc)
{
struct vga_device *vgadev;
unsigned long flags;
/* The one who calls us should check for this, but lets be sure... */
if (pdev == NULL)
pdev = vga_default_device();
if (pdev == NULL)
return;
spin_lock_irqsave(&vga_lock, flags);
vgadev = vgadev_find(pdev);
if (vgadev == NULL)
goto bail;
__vga_put(vgadev, rsrc);
bail:
spin_unlock_irqrestore(&vga_lock, flags);
}
EXPORT_SYMBOL(vga_put);
static bool vga_is_firmware_default(struct pci_dev *pdev)
{
#if defined(CONFIG_X86) || defined(CONFIG_IA64)
u64 base = screen_info.lfb_base;
u64 size = screen_info.lfb_size;
u64 limit;
resource_size_t start, end;
unsigned long flags;
int i;
/* Select the device owning the boot framebuffer if there is one */
if (screen_info.capabilities & VIDEO_CAPABILITY_64BIT_BASE)
base |= (u64)screen_info.ext_lfb_base << 32;
limit = base + size;
/* Does firmware framebuffer belong to us? */
for (i = 0; i < DEVICE_COUNT_RESOURCE; i++) {
flags = pci_resource_flags(pdev, i);
if ((flags & IORESOURCE_MEM) == 0)
continue;
start = pci_resource_start(pdev, i);
end = pci_resource_end(pdev, i);
if (!start || !end)
continue;
if (base < start || limit >= end)
continue;
return true;
}
#endif
return false;
}
static bool vga_arb_integrated_gpu(struct device *dev)
{
#if defined(CONFIG_ACPI)
struct acpi_device *adev = ACPI_COMPANION(dev);
return adev && !strcmp(acpi_device_hid(adev), ACPI_VIDEO_HID);
#else
return false;
#endif
}
/*
* Return true if vgadev is a better default VGA device than the best one
* we've seen so far.
*/
static bool vga_is_boot_device(struct vga_device *vgadev)
{
struct vga_device *boot_vga = vgadev_find(vga_default_device());
struct pci_dev *pdev = vgadev->pdev;
u16 cmd, boot_cmd;
/*
* We select the default VGA device in this order:
* Firmware framebuffer (see vga_arb_select_default_device())
* Legacy VGA device (owns VGA_RSRC_LEGACY_MASK)
* Non-legacy integrated device (see vga_arb_select_default_device())
* Non-legacy discrete device (see vga_arb_select_default_device())
* Other device (see vga_arb_select_default_device())
*/
/*
* We always prefer a firmware default device, so if we've already
* found one, there's no need to consider vgadev.
*/
if (boot_vga && boot_vga->is_firmware_default)
return false;
if (vga_is_firmware_default(pdev)) {
vgadev->is_firmware_default = true;
return true;
}
/*
* A legacy VGA device has MEM and IO enabled and any bridges
* leading to it have PCI_BRIDGE_CTL_VGA enabled so the legacy
* resources ([mem 0xa0000-0xbffff], [io 0x3b0-0x3bb], etc) are
* routed to it.
*
* We use the first one we find, so if we've already found one,
* vgadev is no better.
*/
if (boot_vga &&
(boot_vga->owns & VGA_RSRC_LEGACY_MASK) == VGA_RSRC_LEGACY_MASK)
return false;
if ((vgadev->owns & VGA_RSRC_LEGACY_MASK) == VGA_RSRC_LEGACY_MASK)
return true;
/*
* If we haven't found a legacy VGA device, accept a non-legacy
* device. It may have either IO or MEM enabled, and bridges may
* not have PCI_BRIDGE_CTL_VGA enabled, so it may not be able to
* use legacy VGA resources. Prefer an integrated GPU over others.
*/
pci_read_config_word(pdev, PCI_COMMAND, &cmd);
if (cmd & (PCI_COMMAND_IO | PCI_COMMAND_MEMORY)) {
/*
* An integrated GPU overrides a previous non-legacy
* device. We expect only a single integrated GPU, but if
* there are more, we use the *last* because that was the
* previous behavior.
*/
if (vga_arb_integrated_gpu(&pdev->dev))
return true;
/*
* We prefer the first non-legacy discrete device we find.
* If we already found one, vgadev is no better.
*/
if (boot_vga) {
pci_read_config_word(boot_vga->pdev, PCI_COMMAND,
&boot_cmd);
if (boot_cmd & (PCI_COMMAND_IO | PCI_COMMAND_MEMORY))
return false;
}
return true;
}
/*
* vgadev has neither IO nor MEM enabled. If we haven't found any
* other VGA devices, it is the best candidate so far.
*/
if (!boot_vga)
return true;
return false;
}
/*
* Rules for using a bridge to control a VGA descendant decoding: if a bridge
* has only one VGA descendant then it can be used to control the VGA routing
* for that device. It should always use the bridge closest to the device to
* control it. If a bridge has a direct VGA descendant, but also have a sub-
* bridge VGA descendant then we cannot use that bridge to control the direct
* VGA descendant. So for every device we register, we need to iterate all
* its parent bridges so we can invalidate any devices using them properly.
*/
static void vga_arbiter_check_bridge_sharing(struct vga_device *vgadev)
{
struct vga_device *same_bridge_vgadev;
struct pci_bus *new_bus, *bus;
struct pci_dev *new_bridge, *bridge;
vgadev->bridge_has_one_vga = true;
if (list_empty(&vga_list)) {
vgaarb_info(&vgadev->pdev->dev, "bridge control possible\n");
return;
}
/* okay iterate the new devices bridge hierarachy */
new_bus = vgadev->pdev->bus;
while (new_bus) {
new_bridge = new_bus->self;
/* go through list of devices already registered */
list_for_each_entry(same_bridge_vgadev, &vga_list, list) {
bus = same_bridge_vgadev->pdev->bus;
bridge = bus->self;
/* see if the share a bridge with this device */
if (new_bridge == bridge) {
/*
* If their direct parent bridge is the same
* as any bridge of this device then it can't
* be used for that device.
*/
same_bridge_vgadev->bridge_has_one_vga = false;
}
/*
* Now iterate the previous devices bridge hierarchy.
* If the new devices parent bridge is in the other
* devices hierarchy then we can't use it to control
* this device
*/
while (bus) {
bridge = bus->self;
if (bridge && bridge == vgadev->pdev->bus->self)
vgadev->bridge_has_one_vga = false;
bus = bus->parent;
}
}
new_bus = new_bus->parent;
}
if (vgadev->bridge_has_one_vga)
vgaarb_info(&vgadev->pdev->dev, "bridge control possible\n");
else
vgaarb_info(&vgadev->pdev->dev, "no bridge control possible\n");
}
/*
* Currently, we assume that the "initial" setup of the system is
* not sane, that is we come up with conflicting devices and let
* the arbiter's client decides if devices decodes or not legacy
* things.
*/
static bool vga_arbiter_add_pci_device(struct pci_dev *pdev)
{
struct vga_device *vgadev;
unsigned long flags;
struct pci_bus *bus;
struct pci_dev *bridge;
u16 cmd;
/* Only deal with VGA class devices */
if ((pdev->class >> 8) != PCI_CLASS_DISPLAY_VGA)
return false;
/* Allocate structure */
vgadev = kzalloc(sizeof(struct vga_device), GFP_KERNEL);
if (vgadev == NULL) {
vgaarb_err(&pdev->dev, "failed to allocate VGA arbiter data\n");
/*
* What to do on allocation failure ? For now, let's just do
* nothing, I'm not sure there is anything saner to be done.
*/
return false;
}
/* Take lock & check for duplicates */
spin_lock_irqsave(&vga_lock, flags);
if (vgadev_find(pdev) != NULL) {
BUG_ON(1);
goto fail;
}
vgadev->pdev = pdev;
/* By default, assume we decode everything */
vgadev->decodes = VGA_RSRC_LEGACY_IO | VGA_RSRC_LEGACY_MEM |
VGA_RSRC_NORMAL_IO | VGA_RSRC_NORMAL_MEM;
/* by default mark it as decoding */
vga_decode_count++;
/* Mark that we "own" resources based on our enables, we will
* clear that below if the bridge isn't forwarding
*/
pci_read_config_word(pdev, PCI_COMMAND, &cmd);
if (cmd & PCI_COMMAND_IO)
vgadev->owns |= VGA_RSRC_LEGACY_IO;
if (cmd & PCI_COMMAND_MEMORY)
vgadev->owns |= VGA_RSRC_LEGACY_MEM;
/* Check if VGA cycles can get down to us */
bus = pdev->bus;
while (bus) {
bridge = bus->self;
if (bridge) {
u16 l;
pci_read_config_word(bridge, PCI_BRIDGE_CONTROL, &l);
if (!(l & PCI_BRIDGE_CTL_VGA)) {
vgadev->owns = 0;
break;
}
}
bus = bus->parent;
}
if (vga_is_boot_device(vgadev)) {
vgaarb_info(&pdev->dev, "setting as boot VGA device%s\n",
vga_default_device() ?
" (overriding previous)" : "");
vga_set_default_device(pdev);
}
vga_arbiter_check_bridge_sharing(vgadev);
/* Add to the list */
list_add_tail(&vgadev->list, &vga_list);
vga_count++;
vgaarb_info(&pdev->dev, "VGA device added: decodes=%s,owns=%s,locks=%s\n",
vga_iostate_to_str(vgadev->decodes),
vga_iostate_to_str(vgadev->owns),
vga_iostate_to_str(vgadev->locks));
spin_unlock_irqrestore(&vga_lock, flags);
return true;
fail:
spin_unlock_irqrestore(&vga_lock, flags);
kfree(vgadev);
return false;
}
static bool vga_arbiter_del_pci_device(struct pci_dev *pdev)
{
struct vga_device *vgadev;
unsigned long flags;
bool ret = true;
spin_lock_irqsave(&vga_lock, flags);
vgadev = vgadev_find(pdev);
if (vgadev == NULL) {
ret = false;
goto bail;
}
if (vga_default == pdev)
vga_set_default_device(NULL);
if (vgadev->decodes & (VGA_RSRC_LEGACY_IO | VGA_RSRC_LEGACY_MEM))
vga_decode_count--;
/* Remove entry from list */
list_del(&vgadev->list);
vga_count--;
/* Wake up all possible waiters */
wake_up_all(&vga_wait_queue);
bail:
spin_unlock_irqrestore(&vga_lock, flags);
kfree(vgadev);
return ret;
}
/* this is called with the lock */
static inline void vga_update_device_decodes(struct vga_device *vgadev,
int new_decodes)
{
struct device *dev = &vgadev->pdev->dev;
int old_decodes, decodes_removed, decodes_unlocked;
old_decodes = vgadev->decodes;
decodes_removed = ~new_decodes & old_decodes;
decodes_unlocked = vgadev->locks & decodes_removed;
vgadev->decodes = new_decodes;
vgaarb_info(dev, "changed VGA decodes: olddecodes=%s,decodes=%s:owns=%s\n",
vga_iostate_to_str(old_decodes),
vga_iostate_to_str(vgadev->decodes),
vga_iostate_to_str(vgadev->owns));
/* if we removed locked decodes, lock count goes to zero, and release */
if (decodes_unlocked) {
if (decodes_unlocked & VGA_RSRC_LEGACY_IO)
vgadev->io_lock_cnt = 0;
if (decodes_unlocked & VGA_RSRC_LEGACY_MEM)
vgadev->mem_lock_cnt = 0;
__vga_put(vgadev, decodes_unlocked);
}
/* change decodes counter */
if (old_decodes & VGA_RSRC_LEGACY_MASK &&
!(new_decodes & VGA_RSRC_LEGACY_MASK))
vga_decode_count--;
if (!(old_decodes & VGA_RSRC_LEGACY_MASK) &&
new_decodes & VGA_RSRC_LEGACY_MASK)
vga_decode_count++;
vgaarb_dbg(dev, "decoding count now is: %d\n", vga_decode_count);
}
static void __vga_set_legacy_decoding(struct pci_dev *pdev,
unsigned int decodes,
bool userspace)
{
struct vga_device *vgadev;
unsigned long flags;
decodes &= VGA_RSRC_LEGACY_MASK;
spin_lock_irqsave(&vga_lock, flags);
vgadev = vgadev_find(pdev);
if (vgadev == NULL)
goto bail;
/* don't let userspace futz with kernel driver decodes */
if (userspace && vgadev->set_decode)
goto bail;
/* update the device decodes + counter */
vga_update_device_decodes(vgadev, decodes);
/* XXX if somebody is going from "doesn't decode" to "decodes" state
* here, additional care must be taken as we may have pending owner
* ship of non-legacy region ...
*/
bail:
spin_unlock_irqrestore(&vga_lock, flags);
}
/**
* vga_set_legacy_decoding
* @pdev: pci device of the VGA card
* @decodes: bit mask of what legacy regions the card decodes
*
* Indicates to the arbiter if the card decodes legacy VGA IOs, legacy VGA
* Memory, both, or none. All cards default to both, the card driver (fbdev for
* example) should tell the arbiter if it has disabled legacy decoding, so the
* card can be left out of the arbitration process (and can be safe to take
* interrupts at any time.
*/
void vga_set_legacy_decoding(struct pci_dev *pdev, unsigned int decodes)
{
__vga_set_legacy_decoding(pdev, decodes, false);
}
EXPORT_SYMBOL(vga_set_legacy_decoding);
/**
* vga_client_register - register or unregister a VGA arbitration client
* @pdev: pci device of the VGA client
* @set_decode: vga decode change callback
*
* Clients have two callback mechanisms they can use.
*
* @set_decode callback: If a client can disable its GPU VGA resource, it
* will get a callback from this to set the encode/decode state.
*
* Rationale: we cannot disable VGA decode resources unconditionally some single
* GPU laptops seem to require ACPI or BIOS access to the VGA registers to
* control things like backlights etc. Hopefully newer multi-GPU laptops do
* something saner, and desktops won't have any special ACPI for this. The
* driver will get a callback when VGA arbitration is first used by userspace
* since some older X servers have issues.
*
* This function does not check whether a client for @pdev has been registered
* already.
*
* To unregister just call vga_client_unregister().
*
* Returns: 0 on success, -1 on failure
*/
int vga_client_register(struct pci_dev *pdev,
unsigned int (*set_decode)(struct pci_dev *pdev, bool decode))
{
int ret = -ENODEV;
struct vga_device *vgadev;
unsigned long flags;
spin_lock_irqsave(&vga_lock, flags);
vgadev = vgadev_find(pdev);
if (!vgadev)
goto bail;
vgadev->set_decode = set_decode;
ret = 0;
bail:
spin_unlock_irqrestore(&vga_lock, flags);
return ret;
}
EXPORT_SYMBOL(vga_client_register);