Re: [PATCH] vga: implements VGA arbitration on Linux

From: Jesse Barnes
Date: Mon Aug 17 2009 - 13:37:52 EST

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In reply to: Tiago Vignatti: "Re: [PATCH] vga: implements VGA arbitration on Linux"
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Can you send a patch for this stuff? Maybe it could be rolled in with
a fix for the warnings...

Thanks,
Jesse

On Sun, 16 Aug 2009 18:17:46 +0300
Tiago Vignatti <tiago.vignatti@xxxxxxxxx> wrote:

>
> Hi Jesse,
>
> Just for completeness, there are some perfectionisms clean ups that I
> catch bellow.
>
>
> On Tue, Aug 11, 2009 at 07:52:06AM +0200, Dave Airlie wrote:
> > From: Tiago Vignatti <tiago.vignatti@xxxxxxxxx>
> >
> > Background:
> > Graphic devices are accessed through ranges in I/O or memory space.
> > While most modern devices allow relocation of such ranges, some
> > "Legacy" VGA devices implemented on PCI will typically have the
> > same "hard-decoded" addresses as they did on ISA. For more details
> > see "PCI Bus Binding to IEEE Std 1275-1994 Standard for Boot
> > (Initialization Configuration) Firmware Revision 2.1" Section 7,
> > Legacy Devices.
> >
> > The Resource Access Control (RAC) module inside the X server
> > currently does
>
> RAC already gone away. Finally!
>
>
> > the task of arbitration when more than one legacy device co-exists
> > on the same machine. But the problem happens when these devices are
> > trying to be accessed by different userspace clients (e.g. two
> > server in parallel). Their address assignments conflict. Therefore
> > an arbitration scheme _outside_ of the X server is needed to
> > control the sharing of these resources. This document
> ^^^^^^^^
> AFAIK a patch is not a
> document :)
>
>
> > introduces the operation of the VGA arbiter implemented for Linux
> > kernel.
> >
> > Signed-off-by: Tiago Vignatti <tiago.vignatti@xxxxxxxxx>
> > Signed-off-by: Dave Airlie <airlied@xxxxxxxxxx>
> > ---
> > drivers/gpu/Makefile | 2 +-
> > drivers/gpu/vga/Kconfig | 10 +
> > drivers/gpu/vga/Makefile | 1 +
> > drivers/gpu/vga/vgaarb.c | 1206
> > ++++++++++++++++++++++++++++++++++++++++++++++
> > drivers/pci/pci.c | 44 ++ drivers/video/Kconfig | 2 +
> > include/linux/pci.h | 2 +
> > include/linux/vgaarb.h | 195 ++++++++
> > 8 files changed, 1461 insertions(+), 1 deletions(-)
> > create mode 100644 drivers/gpu/vga/Kconfig
> > create mode 100644 drivers/gpu/vga/Makefile
> > create mode 100644 drivers/gpu/vga/vgaarb.c
> > create mode 100644 include/linux/vgaarb.h
> >
> > diff --git a/drivers/gpu/Makefile b/drivers/gpu/Makefile
> > index de566cf..30879df 100644
> > --- a/drivers/gpu/Makefile
> > +++ b/drivers/gpu/Makefile
> > @@ -1 +1 @@
> > -obj-y += drm/
> > +obj-y += drm/ vga/
> > diff --git a/drivers/gpu/vga/Kconfig b/drivers/gpu/vga/Kconfig
> > new file mode 100644
> > index 0000000..790e675
> > --- /dev/null
> > +++ b/drivers/gpu/vga/Kconfig
> > @@ -0,0 +1,10 @@
> > +config VGA_ARB
> > + bool "VGA Arbitration" if EMBEDDED
> > + default y
> > + depends on PCI
> > + help
> > + Some "legacy" VGA devices implemented on PCI typically
> > have the same
> > + hard-decoded addresses as they did on ISA. When multiple
> > PCI devices
> > + are accessed at same time they need some kind of
> > coordination. Please
> > + see Documentation/vgaarbiter.txt for more details. Select
> > this to
> > + enable VGA arbiter.
> > diff --git a/drivers/gpu/vga/Makefile b/drivers/gpu/vga/Makefile
> > new file mode 100644
> > index 0000000..7cc8c1e
> > --- /dev/null
> > +++ b/drivers/gpu/vga/Makefile
> > @@ -0,0 +1 @@
> > +obj-$(CONFIG_VGA_ARB) += vgaarb.o
> > diff --git a/drivers/gpu/vga/vgaarb.c b/drivers/gpu/vga/vgaarb.c
> > new file mode 100644
> > index 0000000..199138f
> > --- /dev/null
> > +++ b/drivers/gpu/vga/vgaarb.c
> > @@ -0,0 +1,1206 @@
> > +/*
> > + * vgaarb.c
> > + *
> > + * (C) Copyright 2005 Benjamin Herrenschmidt
> > <benh@xxxxxxxxxxxxxxxxxxx>
> > + * (C) Copyright 2007 Paulo R. Zanoni <przanoni@xxxxxxxxx>
> > + * (C) Copyright 2007, 2009 Tiago Vignatti
> > <vignatti@xxxxxxxxxxxxxxx>
> > + *
> > + * Implements the VGA arbitration. For details refer to
> > + * Documentation/vgaarbiter.txt
> > + */
> > +
> > +#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/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, "mem", 3) == 0)
> > + goto both;
> > + return 0;
> > +both:
> > + *io_state = VGA_RSRC_LEGACY_IO | VGA_RSRC_LEGACY_MEM;
> > + return 1;
> > +}
> > +
> > +#ifndef __ARCH_HAS_VGA_DEFAULT_DEVICE
> > +/* this is only used a cookie - it should not be dereferenced */
> > +static struct pci_dev *vga_default;
> > +#endif
> > +
> > +static void vga_arb_device_card_gone(struct pci_dev *pdev);
> > +
> > +/* 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;
> > +}
> > +
> > +/* Returns the default VGA device (vgacon's babe) */
> > +#ifndef __ARCH_HAS_VGA_DEFAULT_DEVICE
> > +struct pci_dev *vga_default_device(void)
> > +{
> > + return vga_default;
> > +}
> > +#endif
> > +
> > +static inline void vga_irq_set_state(struct vga_device *vgadev,
> > bool state) +{
> > + if (vgadev->irq_set_state)
> > + vgadev->irq_set_state(vgadev->cookie, state);
> > +}
> > +
> > +
> > +/* 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 occured 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)
> > +{
> > + unsigned int wants, legacy_wants, match;
> > + struct vga_device *conflict;
> > + unsigned int pci_bits;
> > + /* 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;
> > +
> > + pr_devel("%s: %d\n", __func__, rsrc);
> > + pr_devel("%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;
> > +
> > + /* Check if the architecture allows a conflict
> > between those
> > + * 2 devices or if they are on separate domains
> > + */
> > + if (!vga_conflicts(vgadev->pdev, conflict->pdev))
> > + 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 he owns the resource we want.
> > We don't need
> > + * to check "decodes" since it should be impossible
> > to own
> > + * own legacy resources you don't decode unless I
> > have a bug
> > + * in this code...
> > + */
> > + WARN_ON(conflict->owns & ~conflict->decodes);
> > + match = lwants & conflict->owns;
> > + if (!match)
> > + continue;
> > +
> > + /* looks like he doesn't have a lock, we can steal
> > + * them from him
> > + */
> > + vga_irq_set_state(conflict, false);
> > +
> > + pci_bits = 0;
> > + if (lwants &
> > (VGA_RSRC_LEGACY_MEM|VGA_RSRC_NORMAL_MEM))
> > + pci_bits |= PCI_COMMAND_MEMORY;
> > + if (lwants &
> > (VGA_RSRC_LEGACY_IO|VGA_RSRC_NORMAL_IO))
> > + pci_bits |= PCI_COMMAND_IO;
> > +
> > + pci_set_vga_state(conflict->pdev, false, pci_bits,
> > + change_bridge);
> > + conflict->owns &= ~lwants;
> > + /* If he also owned non-legacy, that is no longer
> > the case */
> > + if (lwants & VGA_RSRC_LEGACY_MEM)
> > + conflict->owns &= ~VGA_RSRC_NORMAL_MEM;
> > + if (lwants & VGA_RSRC_LEGACY_IO)
> > + conflict->owns &= ~VGA_RSRC_NORMAL_IO;
> > + }
> > +
> > +enable_them:
> > + /* ok dude, we got it, everybody conflicting has been
> > disabled, let's
> > + * enable us. Make sure we don't mark a bit in "owns" that
> > we don't
> > + * also have in "decodes". We can lock resources we don't
> > decode but
> > + * not own them.
> > + */
> > + pci_bits = 0;
> > + 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;
> > + pci_set_vga_state(vgadev->pdev, true, pci_bits, !!(wants &
> > VGA_RSRC_LEGACY_MASK)); +
> > + vga_irq_set_state(vgadev, true);
> > + vgadev->owns |= (wants & vgadev->decodes);
> > +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)
> > +{
> > + unsigned int old_locks = vgadev->locks;
> > +
> > + pr_devel("%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);
> > +}
> > +
> > +int vga_get(struct pci_dev *pdev, unsigned int rsrc, int
> > interruptible) +{
> > + struct vga_device *vgadev, *conflict;
> > + unsigned long flags;
> > + wait_queue_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 (signal_pending(current)) {
> > + rc = -EINTR;
> > + break;
> > + }
> > + schedule();
> > + remove_wait_queue(&vga_wait_queue, &wait);
> > + set_current_state(TASK_RUNNING);
> > + }
> > + return rc;
> > +}
> > +EXPORT_SYMBOL(vga_get);
> > +
> > +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;
> > +}
> > +EXPORT_SYMBOL(vga_tryget);
> > +
> > +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);
> > +
> > +/*
> > + * 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 = kmalloc(sizeof(struct vga_device), GFP_KERNEL);
> > + if (vgadev == NULL) {
> > + pr_err("vgaarb: failed to allocate pci device\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;
> > + }
> > +
> > + memset(vgadev, 0, sizeof(*vgadev));
> > +
> > + /* 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;
> > + }
> > +
> > + /* Deal with VGA default device. Use first enabled one
> > + * by default if arch doesn't have it's own hook
> > + */
> > +#ifndef __ARCH_HAS_VGA_DEFAULT_DEVICE
> > + if (vga_default == NULL &&
> > + ((vgadev->owns & VGA_RSRC_LEGACY_MASK) ==
> > VGA_RSRC_LEGACY_MASK))
> > + vga_default = pci_dev_get(pdev);
> > +#endif
> > +
> > + /* Add to the list */
> > + list_add(&vgadev->list, &vga_list);
> > + vga_count++;
> > + pr_info("vgaarb: device added:
> > PCI:%s,decodes=%s,owns=%s,locks=%s\n",
> > + pci_name(pdev),
> > + 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) {
> > + pci_dev_put(vga_default);
> > + vga_default = 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--;
> > + /* Notify userland driver that the device is gone so it
> > discards
> > + * it's copies of the pci_dev pointer
> > + */
> > + vga_arb_device_card_gone(pdev);
> > +
> > + /* 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)
> > +{
> > + int old_decodes;
> > + struct vga_device *new_vgadev, *conflict;
> > +
> > + old_decodes = vgadev->decodes;
> > + vgadev->decodes = new_decodes;
> > +
> > + pr_info("vgaarb: device changed decodes:
> > PCI:%s,olddecodes=%s,decodes=%s:owns=%s\n",
> > + pci_name(vgadev->pdev),
> > + vga_iostate_to_str(old_decodes),
> > + vga_iostate_to_str(vgadev->decodes),
> > + vga_iostate_to_str(vgadev->owns));
> > +
> > +
> > + /* if we own the decodes we should move them along to
> > + another card */
> > + if ((vgadev->owns & old_decodes) && (vga_count > 1)) {
> > + /* set us to own nothing */
> > + vgadev->owns &= ~old_decodes;
> > + list_for_each_entry(new_vgadev, &vga_list, list) {
> > + if ((new_vgadev != vgadev) &&
> > + (new_vgadev->decodes &
> > VGA_RSRC_LEGACY_MASK)) {
> > + pr_info("vgaarb: transferring owner
> > from PCI:%s to PCI:%s\n", pci_name(vgadev->pdev),
> > pci_name(new_vgadev->pdev));
> > + conflict = __vga_tryget(new_vgadev,
> > VGA_RSRC_LEGACY_MASK);
> > + if (!conflict)
> > + __vga_put(new_vgadev,
> > VGA_RSRC_LEGACY_MASK);
> > + break;
> > + }
> > + }
> > + }
> > +
> > + /* change decodes counter */
> > + if (old_decodes != new_decodes) {
> > + if (new_decodes & (VGA_RSRC_LEGACY_IO |
> > VGA_RSRC_LEGACY_MEM))
> > + vga_decode_count++;
> > + else
> > + vga_decode_count--;
> > + }
> > +}
> > +
> > +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_vga_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);
> > +}
> > +
> > +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);
> > +
> > +/* return number of active VGA devices */
> > +/* call with NULL to unregister */
> > +int vga_client_register(struct pci_dev *pdev, void *cookie,
> > + void (*irq_set_state)(void *cookie, bool
> > state),
> > + unsigned int (*set_vga_decode)(void
> > *cookie, bool decode)) +{
> > + int ret = -1;
> > + struct vga_device *vgadev;
> > + unsigned long flags;
> > +
> > + spin_lock_irqsave(&vga_lock, flags);
> > + vgadev = vgadev_find(pdev);
> > + if (!vgadev)
> > + goto bail;
> > +
> > + vgadev->irq_set_state = irq_set_state;
> > + vgadev->set_vga_decode = set_vga_decode;
> > + vgadev->cookie = cookie;
> > + ret = 0;
> > +
> > +bail:
> > + spin_unlock_irqrestore(&vga_lock, flags);
> > + return ret;
> > +
> > +}
> > +EXPORT_SYMBOL(vga_client_register);
> > +
> > +/*
> > + * Char driver implementation
> > + *
> > + * Semantics is:
> > + *
> > + * open : open user instance of the arbitrer. by default,
> > it's
> > + * attached to the default VGA device of the system.
> > + *
> > + * close : close user instance, release locks
> > + *
> > + * read : return a string indicating the status of the
> > target.
> > + * an IO state string is of the form
> > {io,mem,io+mem,none},
> > + * mc and ic are respectively mem and io lock
> > counts (for
> > + * debugging/diagnostic only). "decodes" indicate
> > what the
> > + * card currently decodes, "owns" indicates what is
> > currently
> > + * enabled on it, and "locks" indicates what is
> > locked by this
> > + * card. If the card is unplugged, we get "invalid"
> > then for
> > + * card_ID and an -ENODEV error is returned for any
> > command
> > + * until a new card is targeted
> > + *
> > + *
> > "<card_ID>,decodes=<io_state>,owns=<io_state>,locks=<io_state>
> > (ic,mc)"
> > + *
> > + * write : write a command to the arbiter. List of commands
> > is:
> > + *
> > + * target <card_ID> : switch target to card <card_ID> (see
> > below)
> > + * lock <io_state> : acquires locks on target ("none" is
> > invalid io_state)
> > + * trylock <io_state> : non-blocking acquire locks on target
> > + * unlock <io_state> : release locks on target
> > + * unlock all : release all locks on target held by this
> > user
> > + * decodes <io_state> : set the legacy decoding attributes for
> > the card
> > + *
> > + * poll : event if something change on any card (not just
> > the target)
> > + *
> > + * card_ID is of the form "PCI:domain:bus:dev.fn". It can be set
> > to "default"
> > + * to go back to the system default card (TODO: not implemented
> > yet).
> > + * Currently, only PCI is supported as a prefix, but the userland
> > API may
> > + * support other bus types in the future, even if the current
> > kernel
> > + * implementation doesn't.
> > + *
> > + * Note about locks:
> > + *
> > + * The driver keeps track of which user has what locks on which
> > card. It
> > + * supports stacking, like the kernel one. This complexifies the
> > implementation
> > + * a bit, but makes the arbiter more tolerant to userspace
> > problems and able
> > + * to properly cleanup in all cases when a process dies.
> > + * Currently, a max of 16 cards simultaneously can have locks
> > issued from
> > + * userspace for a given user (file descriptor instance) of the
> > arbiter.
> > + *
> > + * If the device is hot-unplugged, there is a hook inside the
> > module to notify
> > + * they being added/removed in the system and automatically
> > added/removed in
> > + * the arbiter.
> > + */
> > +
> > +#define MAX_USER_CARDS 16
> > +#define PCI_INVALID_CARD ((struct pci_dev *)-1UL)
> > +
> > +/*
> > + * Each user has an array of these, tracking which cards have locks
> > + */
> > +struct vga_arb_user_card {
> > + struct pci_dev *pdev;
> > + unsigned int mem_cnt;
> > + unsigned int io_cnt;
> > +};
> > +
> > +struct vga_arb_private {
> > + struct list_head list;
> > + struct pci_dev *target;
> > + struct vga_arb_user_card cards[MAX_USER_CARDS];
> > + spinlock_t lock;
> > +};
> > +
> > +static LIST_HEAD(vga_user_list);
> > +static DEFINE_SPINLOCK(vga_user_lock);
> > +
> > +
> > +/*
> > + * This function gets a string in the format:
> > "PCI:domain:bus:dev.fn" and
> > + * returns the respective values. If the string is not in this
> > format,
> > + * it returns 0.
> > + */
> > +static int vga_pci_str_to_vars(char *buf, int count, unsigned int
> > *domain,
> > + unsigned int *bus, unsigned int
> > *devfn) +{
> > + int n;
> > + unsigned int slot, func;
> > +
> > +
> > + n = sscanf(buf, "PCI:%x:%x:%x.%x", domain, bus, &slot,
> > &func);
> > + if (n != 4)
> > + return 0;
> > +
> > + *devfn = PCI_DEVFN(slot, func);
> > +
> > + return 1;
> > +}
> > +
> > +static ssize_t vga_arb_read(struct file *file, char __user * buf,
> > + size_t count, loff_t *ppos)
> > +{
> > + struct vga_arb_private *priv = file->private_data;
> > + struct vga_device *vgadev;
> > + struct pci_dev *pdev;
> > + unsigned long flags;
> > + size_t len;
> > + int rc;
> > + char *lbuf;
> > +
> > + lbuf = kmalloc(1024, GFP_KERNEL);
> > + if (lbuf == NULL)
> > + return -ENOMEM;
> > +
> > + /* Shields against vga_arb_device_card_gone (pci_dev going
> > + * away), and allows access to vga list
> > + */
> > + spin_lock_irqsave(&vga_lock, flags);
> > +
> > + /* If we are targetting the default, use it */
> > + pdev = priv->target;
> > + if (pdev == NULL || pdev == PCI_INVALID_CARD) {
> > + spin_unlock_irqrestore(&vga_lock, flags);
> > + len = sprintf(lbuf, "invalid");
> > + goto done;
> > + }
> > +
> > + /* Find card vgadev structure */
> > + vgadev = vgadev_find(pdev);
> > + if (vgadev == NULL) {
> > + /* Wow, it's not in the list, that shouldn't happen,
> > + * let's fix us up and return invalid card
> > + */
> > + if (pdev == priv->target)
> > + vga_arb_device_card_gone(pdev);
> > + spin_unlock_irqrestore(&vga_lock, flags);
> > + len = sprintf(lbuf, "invalid");
> > + goto done;
> > + }
> > +
> > + /* Fill the buffer with infos */
> > + len = snprintf(lbuf, 1024,
> > +
> > "count:%d,PCI:%s,decodes=%s,owns=%s,locks=%s(%d:%d)\n",
> > + vga_decode_count, pci_name(pdev),
> > + vga_iostate_to_str(vgadev->decodes),
> > + vga_iostate_to_str(vgadev->owns),
> > + vga_iostate_to_str(vgadev->locks),
> > + vgadev->io_lock_cnt, vgadev->mem_lock_cnt);
> > +
> > + spin_unlock_irqrestore(&vga_lock, flags);
> > +done:
> > +
> > + /* Copy that to user */
> > + if (len > count)
> > + len = count;
> > + rc = copy_to_user(buf, lbuf, len);
> > + kfree(lbuf);
> > + if (rc)
> > + return -EFAULT;
> > + return len;
> > +}
> > +
> > +/*
> > + * TODO: To avoid parsing inside kernel and to improve the speed
> > we may
> > + * consider use ioctl here
> > + */
> > +static ssize_t vga_arb_write(struct file *file, const char __user
> > * buf,
> > + size_t count, loff_t *ppos)
> > +{
> > + struct vga_arb_private *priv = file->private_data;
> > + struct vga_arb_user_card *uc = NULL;
> > + struct pci_dev *pdev;
> > +
> > + unsigned int io_state;
> > +
> > + char *kbuf, *curr_pos;
> > + size_t remaining = count;
> > +
> > + int ret_val;
> > + int i;
> > +
> > +
> > + kbuf = kmalloc(count + 1, GFP_KERNEL);
> > + if (!kbuf)
> > + return -ENOMEM;
> > +
> > + if (copy_from_user(kbuf, buf, count)) {
> > + kfree(kbuf);
> > + return -EFAULT;
> > + }
> > + curr_pos = kbuf;
> > + kbuf[count] = '\0'; /* Just to make sure... */
> > +
> > + if (strncmp(curr_pos, "lock ", 5) == 0) {
> > + curr_pos += 5;
> > + remaining -= 5;
> > +
> > + pr_devel("client 0x%X called 'lock'\n", (int)priv);
> > +
> > + if (!vga_str_to_iostate(curr_pos, remaining,
> > &io_state)) {
> > + ret_val = -EPROTO;
> > + goto done;
> > + }
> > + if (io_state == VGA_RSRC_NONE) {
> > + ret_val = -EPROTO;
> > + goto done;
> > + }
> > +
> > + pdev = priv->target;
> > + if (priv->target == NULL) {
> > + ret_val = -ENODEV;
> > + goto done;
> > + }
> > +
> > + vga_get_uninterruptible(pdev, io_state);
> > +
> > + /* Update the client's locks lists... */
> > + for (i = 0; i < MAX_USER_CARDS; i++) {
> > + if (priv->cards[i].pdev == pdev) {
> > + if (io_state & VGA_RSRC_LEGACY_IO)
> > + priv->cards[i].io_cnt++;
> > + if (io_state & VGA_RSRC_LEGACY_MEM)
> > + priv->cards[i].mem_cnt++;
> > + break;
> > + }
> > + }
> > +
> > + ret_val = count;
> > + goto done;
> > + } else if (strncmp(curr_pos, "unlock ", 7) == 0) {
> > + curr_pos += 7;
> > + remaining -= 7;
> > +
> > + pr_devel("client 0x%X called 'unlock'\n",
> > (int)priv); +
> > + if (strncmp(curr_pos, "all", 3) == 0)
> > + io_state = VGA_RSRC_LEGACY_IO |
> > VGA_RSRC_LEGACY_MEM;
> > + else {
> > + if (!vga_str_to_iostate
> > + (curr_pos, remaining, &io_state)) {
> > + ret_val = -EPROTO;
> > + goto done;
> > + }
> > + /* TODO: Add this?
> > + if (io_state == VGA_RSRC_NONE) {
> > + ret_val = -EPROTO;
> > + goto done;
> > + }
> > + */
> > + }
> > +
> > + pdev = priv->target;
> > + if (priv->target == NULL) {
> > + ret_val = -ENODEV;
> > + goto done;
> > + }
> > + for (i = 0; i < MAX_USER_CARDS; i++) {
> > + if (priv->cards[i].pdev == pdev)
> > + uc = &priv->cards[i];
> > + }
> > +
> > + if (!uc)
> > + return -EINVAL;
> > +
> > + if (io_state & VGA_RSRC_LEGACY_IO && uc->io_cnt ==
> > 0)
> > + return -EINVAL;
> > +
> > + if (io_state & VGA_RSRC_LEGACY_MEM && uc->mem_cnt
> > == 0)
> > + return -EINVAL;
> > +
> > + vga_put(pdev, io_state);
> > +
> > + if (io_state & VGA_RSRC_LEGACY_IO)
> > + uc->io_cnt--;
> > + if (io_state & VGA_RSRC_LEGACY_MEM)
> > + uc->mem_cnt--;
> > +
> > + ret_val = count;
> > + goto done;
> > + } else if (strncmp(curr_pos, "trylock ", 8) == 0) {
> > + curr_pos += 8;
> > + remaining -= 8;
> > +
> > + pr_devel("client 0x%X called 'trylock'\n",
> > (int)priv); +
> > + if (!vga_str_to_iostate(curr_pos, remaining,
> > &io_state)) {
> > + ret_val = -EPROTO;
> > + goto done;
> > + }
> > + /* TODO: Add this?
> > + if (io_state == VGA_RSRC_NONE) {
> > + ret_val = -EPROTO;
> > + goto done;
> > + }
> > + */
> > +
> > + pdev = priv->target;
> > + if (priv->target == NULL) {
> > + ret_val = -ENODEV;
> > + goto done;
> > + }
> > +
> > + if (vga_tryget(pdev, io_state)) {
> > + /* Update the client's locks lists... */
> > + for (i = 0; i < MAX_USER_CARDS; i++) {
> > + if (priv->cards[i].pdev == pdev) {
> > + if (io_state &
> > VGA_RSRC_LEGACY_IO)
> > +
> > priv->cards[i].io_cnt++;
> > + if (io_state &
> > VGA_RSRC_LEGACY_MEM)
> > +
> > priv->cards[i].mem_cnt++;
> > + break;
> > + }
> > + }
> > + ret_val = count;
> > + goto done;
> > + } else {
> > + ret_val = -EBUSY;
> > + goto done;
> > + }
> > +
> > + } else if (strncmp(curr_pos, "target ", 7) == 0) {
> > + unsigned int domain, bus, devfn;
> > + struct vga_device *vgadev;
> > +
> > + curr_pos += 7;
> > + remaining -= 7;
> > + pr_devel("client 0x%X called 'target'\n",
> > (int)priv);
> > + /* if target is default */
> > + if (!strncmp(buf, "default", 7))
> > + pdev = pci_dev_get(vga_default_device());
> > + else {
> > + if (!vga_pci_str_to_vars(curr_pos,
> > remaining,
> > + &domain, &bus,
> > &devfn)) {
> > + ret_val = -EPROTO;
> > + goto done;
> > + }
> > +
> > + pdev = pci_get_bus_and_slot(bus, devfn);
> > + if (!pdev) {
> > + pr_info("vgaarb: invalid PCI
> > address!\n");
> > + ret_val = -ENODEV;
> > + goto done;
> > + }
> > + }
> > +
> > + vgadev = vgadev_find(pdev);
> > + if (vgadev == NULL) {
> > + pr_info("vgaarb: this pci device is not a
> > vga device\n");
> > + pci_dev_put(pdev);
> > + ret_val = -ENODEV;
> > + goto done;
> > + }
> > +
> > + priv->target = pdev;
> > + for (i = 0; i < MAX_USER_CARDS; i++) {
> > + if (priv->cards[i].pdev == pdev)
> > + break;
> > + if (priv->cards[i].pdev == NULL) {
> > + priv->cards[i].pdev = pdev;
> > + priv->cards[i].io_cnt = 0;
> > + priv->cards[i].mem_cnt = 0;
> > + break;
> > + }
> > + }
> > + if (i == MAX_USER_CARDS) {
> > + pr_err("vgaarb: maximum user cards number
> > reached!\n");
> > + pci_dev_put(pdev);
> > + /* XXX: which value to return? */
> > + ret_val = -ENOMEM;
> > + goto done;
> > + }
> > +
> > + ret_val = count;
> > + pci_dev_put(pdev);
> > + goto done;
> > +
> > +
> > + } else if (strncmp(curr_pos, "decodes ", 8) == 0) {
> > + curr_pos += 8;
> > + remaining -= 8;
> > + pr_devel("vgaarb: client 0x%X called 'decodes'\n",
> > (int)priv); +
> > + if (!vga_str_to_iostate(curr_pos, remaining,
> > &io_state)) {
> > + ret_val = -EPROTO;
> > + goto done;
> > + }
> > + pdev = priv->target;
> > + if (priv->target == NULL) {
> > + ret_val = -ENODEV;
> > + goto done;
> > + }
> > +
> > + __vga_set_legacy_decoding(pdev, io_state, true);
> > + ret_val = count;
> > + goto done;
> > + }
> > + /* If we got here, the message written is not part of the
> > protocol! */
> > + kfree(kbuf);
> > + return -EPROTO;
> > +
> > +done:
> > + kfree(kbuf);
> > + return ret_val;
> > +}
> > +
> > +static unsigned int vga_arb_fpoll(struct file *file, poll_table *
> > wait) +{
> > + struct vga_arb_private *priv = file->private_data;
> > +
> > + pr_devel("%s\n", __func__);
> > +
> > + if (priv == NULL)
> > + return -ENODEV;
> > + poll_wait(file, &vga_wait_queue, wait);
> > + return POLLIN;
> > +}
> > +
> > +static int vga_arb_open(struct inode *inode, struct file *file)
> > +{
> > + struct vga_arb_private *priv;
> > + unsigned long flags;
> > +
> > + pr_devel("%s\n", __func__);
> > +
> > + priv = kmalloc(sizeof(struct vga_arb_private), GFP_KERNEL);
> > + if (priv == NULL)
> > + return -ENOMEM;
> > + memset(priv, 0, sizeof(*priv));
> > + spin_lock_init(&priv->lock);
> > + file->private_data = priv;
> > +
> > + spin_lock_irqsave(&vga_user_lock, flags);
> > + list_add(&priv->list, &vga_user_list);
> > + spin_unlock_irqrestore(&vga_user_lock, flags);
> > +
> > + /* Set the client' lists of locks */
> > + priv->target = vga_default_device(); /* Maybe this is still
> > null! */
> > + priv->cards[0].pdev = priv->target;
> > + priv->cards[0].io_cnt = 0;
> > + priv->cards[0].mem_cnt = 0;
> > +
> > +
> > + return 0;
> > +}
> > +
> > +static int vga_arb_release(struct inode *inode, struct file *file)
> > +{
> > + struct vga_arb_private *priv = file->private_data;
> > + struct vga_arb_user_card *uc;
> > + unsigned long flags;
> > + int i;
> > +
> > + pr_devel("%s\n", __func__);
> > +
> > + if (priv == NULL)
> > + return -ENODEV;
> > +
> > + spin_lock_irqsave(&vga_user_lock, flags);
> > + list_del(&priv->list);
> > + for (i = 0; i < MAX_USER_CARDS; i++) {
> > + uc = &priv->cards[i];
> > + if (uc->pdev == NULL)
> > + continue;
> > + pr_devel("uc->io_cnt == %d, uc->mem_cnt == %d\n",
> > + uc->io_cnt, uc->mem_cnt);
> > + while (uc->io_cnt--)
> > + vga_put(uc->pdev, VGA_RSRC_LEGACY_IO);
> > + while (uc->mem_cnt--)
> > + vga_put(uc->pdev, VGA_RSRC_LEGACY_MEM);
> > + }
> > + spin_unlock_irqrestore(&vga_user_lock, flags);
> > +
> > + kfree(priv);
> > +
> > + return 0;
> > +}
> > +
> > +static void vga_arb_device_card_gone(struct pci_dev *pdev)
> > +{
> > +}
> > +
> > +/*
> > + * callback any registered clients to let them know we have a
> > + * change in VGA cards
> > + */
> > +static void vga_arbiter_notify_clients(void)
> > +{
> > + struct vga_device *vgadev;
> > + unsigned long flags;
> > + uint32_t new_decodes;
> > + bool new_state;
> > +
> > + if (!vga_arbiter_used)
> > + return;
> > +
> > + spin_lock_irqsave(&vga_lock, flags);
> > + list_for_each_entry(vgadev, &vga_list, list) {
> > + if (vga_count > 1)
> > + new_state = false;
> > + else
> > + new_state = true;
> > + if (vgadev->set_vga_decode) {
> > + new_decodes =
> > vgadev->set_vga_decode(vgadev->cookie, new_state);
> > + vga_update_device_decodes(vgadev,
> > new_decodes);
> > + }
> > + }
> > + spin_unlock_irqrestore(&vga_lock, flags);
> > +}
> > +
> > +static int pci_notify(struct notifier_block *nb, unsigned long
> > action,
> > + void *data)
> > +{
> > + struct device *dev = data;
> > + struct pci_dev *pdev = to_pci_dev(dev);
> > + bool notify = false;
> > +
> > + pr_devel("%s\n", __func__);
> > +
> > + /* For now we're only intereted in devices added and
> > removed. I didn't
> > + * test this thing here, so someone needs to double check
> > for the
> > + * cases of hotplugable vga cards. */
> > + if (action == BUS_NOTIFY_ADD_DEVICE)
> > + notify = vga_arbiter_add_pci_device(pdev);
> > + else if (action == BUS_NOTIFY_DEL_DEVICE)
> > + notify = vga_arbiter_del_pci_device(pdev);
> > +
> > + if (notify)
> > + vga_arbiter_notify_clients();
> > + return 0;
> > +}
> > +
> > +static struct notifier_block pci_notifier = {
> > + .notifier_call = pci_notify,
> > +};
> > +
> > +static const struct file_operations vga_arb_device_fops = {
> > + .read = vga_arb_read,
> > + .write = vga_arb_write,
> > + .poll = vga_arb_fpoll,
> > + .open = vga_arb_open,
> > + .release = vga_arb_release,
> > +};
> > +
> > +static struct miscdevice vga_arb_device = {
> > + MISC_DYNAMIC_MINOR, "vga_arbiter", &vga_arb_device_fops
> > +};
> > +
> > +static int __init vga_arb_device_init(void)
> > +{
> > + int rc;
> > + struct pci_dev *pdev;
> > +
> > + rc = misc_register(&vga_arb_device);
> > + if (rc < 0)
> > + pr_err("vgaarb: error %d registering device\n", rc);
> > +
> > + bus_register_notifier(&pci_bus_type, &pci_notifier);
> > +
> > + /* We add all pci devices satisfying vga class in the
> > arbiter by
> > + * default */
> > + pdev = NULL;
> > + while ((pdev =
> > + pci_get_subsys(PCI_ANY_ID, PCI_ANY_ID, PCI_ANY_ID,
> > + PCI_ANY_ID, pdev)) != NULL)
> > + vga_arbiter_add_pci_device(pdev);
> > +
> > + pr_info("vgaarb: loaded\n");
> > + return rc;
> > +}
> > +subsys_initcall(vga_arb_device_init);
> > diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c
> > index dbd0f94..d837606 100644
> > --- a/drivers/pci/pci.c
> > +++ b/drivers/pci/pci.c
> > @@ -2502,6 +2502,50 @@ int pci_resource_bar(struct pci_dev *dev,
> > int resno, enum pci_bar_type *type) return 0;
> > }
> >
> > +/**
> > + * pci_set_vga_state - set VGA decode state on device and parents
> > if requested
> > + * @dev the PCI device
> > + * @decode - true = enable decoding, false = disable decoding
> > + * @command_bits PCI_COMMAND_IO and/or PCI_COMMAND_MEMORY
> > + * @change_bridge - traverse ancestors and change bridges
> > + */
> > +int pci_set_vga_state(struct pci_dev *dev, bool decode,
> > + unsigned int command_bits, bool change_bridge)
> > +{
> > + struct pci_bus *bus;
> > + struct pci_dev *bridge;
> > + u16 cmd;
> > +
> > + WARN_ON(command_bits &
> > ~(PCI_COMMAND_IO|PCI_COMMAND_MEMORY)); +
> > + pci_read_config_word(dev, PCI_COMMAND, &cmd);
> > + if (decode == true)
> > + cmd |= command_bits;
> > + else
> > + cmd &= ~command_bits;
> > + pci_write_config_word(dev, PCI_COMMAND, cmd);
> > +
> > + if (change_bridge == false)
> > + return 0;
> > +
> > + bus = dev->bus;
> > + while (bus) {
> > + bridge = bus->self;
> > + if (bridge) {
> > + pci_read_config_word(bridge,
> > PCI_BRIDGE_CONTROL,
> > + &cmd);
> > + if (decode == true)
> > + cmd |= PCI_BRIDGE_CTL_VGA;
> > + else
> > + cmd &= ~PCI_BRIDGE_CTL_VGA;
> > + pci_write_config_word(bridge,
> > PCI_BRIDGE_CONTROL,
> > + cmd);
> > + }
> > + bus = bus->parent;
> > + }
> > + return 0;
> > +}
> > +
> > #define RESOURCE_ALIGNMENT_PARAM_SIZE COMMAND_LINE_SIZE
> > static char
> > resource_alignment_param[RESOURCE_ALIGNMENT_PARAM_SIZE] = {0};
> > spinlock_t resource_alignment_lock = SPIN_LOCK_UNLOCKED; diff --git
> > a/drivers/video/Kconfig b/drivers/video/Kconfig index
> > 3b54b39..a0d9ee1 100644 --- a/drivers/video/Kconfig
> > +++ b/drivers/video/Kconfig
> > @@ -7,6 +7,8 @@ menu "Graphics support"
> >
> > source "drivers/char/agp/Kconfig"
> >
> > +source "drivers/gpu/vga/Kconfig"
> > +
> > source "drivers/gpu/drm/Kconfig"
> >
> > config VGASTATE
> > diff --git a/include/linux/pci.h b/include/linux/pci.h
> > index 115fb7b..7ba6eba 100644
> > --- a/include/linux/pci.h
> > +++ b/include/linux/pci.h
> > @@ -805,6 +805,8 @@ int pci_cfg_space_size_ext(struct pci_dev *dev);
> > int pci_cfg_space_size(struct pci_dev *dev);
> > unsigned char pci_bus_max_busnr(struct pci_bus *bus);
> >
> > +int pci_set_vga_state(struct pci_dev *pdev, bool decode,
> > + unsigned int command_bits, bool
> > change_bridge); /* kmem_cache style wrapper around
> > pci_alloc_consistent() */
> >
> > #include <linux/dmapool.h>
> > diff --git a/include/linux/vgaarb.h b/include/linux/vgaarb.h
> > new file mode 100644
> > index 0000000..68229ce
> > --- /dev/null
> > +++ b/include/linux/vgaarb.h
> > @@ -0,0 +1,195 @@
> > +/*
> > + * vgaarb.c
> ^^^^^^^^
> change to vgaarb.h
>
> > + *
> > + * (C) Copyright 2005 Benjamin Herrenschmidt
> > <benh@xxxxxxxxxxxxxxxxxxx>
> > + * (C) Copyright 2007 Paulo R. Zanoni <przanoni@xxxxxxxxx>
> > + * (C) Copyright 2007, 2009 Tiago Vignatti
> > <vignatti@xxxxxxxxxxxxxxx>
> > + */
> > +
> > +#ifndef LINUX_VGA_H
> > +
> > +#include <asm/vga.h>
> > +
> > +/* Legacy VGA regions */
> > +#define VGA_RSRC_NONE 0x00
> > +#define VGA_RSRC_LEGACY_IO 0x01
> > +#define VGA_RSRC_LEGACY_MEM 0x02
> > +#define VGA_RSRC_LEGACY_MASK (VGA_RSRC_LEGACY_IO |
> > VGA_RSRC_LEGACY_MEM) +/* Non-legacy access */
> > +#define VGA_RSRC_NORMAL_IO 0x04
> > +#define VGA_RSRC_NORMAL_MEM 0x08
> > +
> > +/* Passing that instead of a pci_dev to use the system "default"
> > + * device, that is the one used by vgacon. Archs will probably
> > + * have to provide their own vga_default_device();
> > + */
> > +#define VGA_DEFAULT_DEVICE (NULL)
> > +
> > +/* For use by clients */
> > +
> > +/**
> > + * 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.
> > + */
> > +extern void vga_set_legacy_decoding(struct pci_dev *pdev,
> > +
> > unsigned int decodes); +
> > +/**
> > + * 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
> > + * wether 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, inlcuding 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 accesse 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 differenciate VGA memory
> > and IO
> > + * afaik). You can indicate wether 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)
> > + */
> > +
> > +extern int vga_get(struct pci_dev *pdev, unsigned int rsrc,
> > +
> > int interruptible); +
> > +/**
> > + * vga_get_interruptible
> > + *
> > + * Shortcut to vga_get
> > + */
> > +
> > +static inline int vga_get_interruptible(struct pci_dev *pdev,
> > +
> > unsigned int rsrc) +{
> > + return vga_get(pdev, rsrc, 1);
> > +}
> > +
> > +/**
> > + * vga_get_interruptible
> > + *
> > + * Shortcut to vga_get
> > + */
> > +
> > +static inline int vga_get_uninterruptible(struct pci_dev *pdev,
> > +
> > unsigned int rsrc) +{
> > + return vga_get(pdev, rsrc, 0);
> > +}
> > +
> > +/**
> > + * 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
> > + */
> > +
> > +extern int vga_tryget(struct pci_dev *pdev, unsigned int rsrc);
> > +
> > +/**
> > + * 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 function 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.
> > + */
> > +
> > +extern void vga_put(struct pci_dev *pdev, unsigned int rsrc);
> > +
> > +
> > +/**
> > + * vga_default_device
> > + *
> > + * 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()...
> > + */
> > +
> > +#ifndef __ARCH_HAS_VGA_DEFAULT_DEVICE
> > +extern struct pci_dev *vga_default_device(void);
> > +#endif
> > +
> > +/**
> > + * vga_conflicts
> > + *
> > + * Architectures should define this if they have several
> > + * independant PCI domains that can afford concurrent VGA
> > + * decoding
> > + */
> > +
> > +#ifndef __ARCH_HAS_VGA_CONFLICT
> > +static inline int vga_conflicts(struct pci_dev *p1, struct pci_dev
> > *p2) +{
> > + return 1;
> > +}
> > +#endif
> > +
> > +/*
> > + * Register a client with the VGA arbitration logic
> > + * return value: number of VGA devices in system.
> > + *
> > + * Clients have two callback mechanisms they can use.
> > + * irq enable/disable callback -
> > + * If a client can't disable its GPUs VGA resources, then we
> > + * need to be able to ask it to turn off its irqs when we
> > + * turn off its mem and io decoding.
> > + * set_vga_decode
> > + * If a client can disable its GPU VGA resource, it will
> > + * get a callback from this to set the encode/decode state
> > + *
> > + * Clients with disable abilities should check the return value
> > + * of this function and if the VGA device count is > 1, should
> > + * disable VGA decoding resources.
> > + *
> > + * 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.
> > + */
> > +int vga_client_register(struct pci_dev *pdev, void *cookie,
> > + void (*irq_set_state)(void *cookie, bool
> > state),
> > + unsigned int (*set_vga_decode)(void
> > *cookie, bool state)); +
> > +#endif /* LINUX_VGA_H */
> > --
> > 1.6.0.6
> Tiago
>
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Jesse Barnes, Intel Open Source Technology Center
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