diff options
| -rw-r--r-- | drivers/gpu/drm/drm_aperture.c | 221 | ||||
| -rw-r--r-- | include/drm/drm_aperture.h | 4 |
2 files changed, 221 insertions, 4 deletions
diff --git a/drivers/gpu/drm/drm_aperture.c b/drivers/gpu/drm/drm_aperture.c index e034dd7f9b09..33bf018c3bdf 100644 --- a/drivers/gpu/drm/drm_aperture.c +++ b/drivers/gpu/drm/drm_aperture.c @@ -1,9 +1,18 @@ // SPDX-License-Identifier: MIT +#include <linux/device.h> #include <linux/fb.h> +#include <linux/list.h> +#include <linux/mutex.h> +#include <linux/pci.h> +#include <linux/platform_device.h> /* for firmware helpers */ +#include <linux/slab.h> +#include <linux/types.h> #include <linux/vgaarb.h> #include <drm/drm_aperture.h> +#include <drm/drm_drv.h> +#include <drm/drm_print.h> /** * DOC: overview @@ -62,8 +71,200 @@ * framebuffer apertures automatically. Device drivers without knowledge of * the framebuffer's location shall call drm_aperture_remove_framebuffers(), * which removes all drivers for known framebuffer. + * + * Drivers that are susceptible to being removed by other drivers, such as + * generic EFI or VESA drivers, have to register themselves as owners of their + * given framebuffer memory. Ownership of the framebuffer memory is achived + * by calling devm_aperture_acquire_from_firmware(). On success, the driver + * is the owner of the framebuffer range. The function fails if the + * framebuffer is already by another driver. See below for an example. + * + * .. code-block:: c + * + * static int acquire_framebuffers(struct drm_device *dev, struct platform_device *pdev) + * { + * resource_size_t base, size; + * + * mem = platform_get_resource(pdev, IORESOURCE_MEM, 0); + * if (!mem) + * return -EINVAL; + * base = mem->start; + * size = resource_size(mem); + * + * return devm_acquire_aperture_from_firmware(dev, base, size); + * } + * + * static int probe(struct platform_device *pdev) + * { + * struct drm_device *dev; + * int ret; + * + * // ... Initialize the device... + * dev = devm_drm_dev_alloc(); + * ... + * + * // ... and acquire ownership of the framebuffer. + * ret = acquire_framebuffers(dev, pdev); + * if (ret) + * return ret; + * + * drm_dev_register(dev, 0); + * + * return 0; + * } + * + * The generic driver is now subject to forced removal by other drivers. This + * only works for platform drivers that support hot unplug. + * When a driver calls drm_aperture_remove_conflicting_framebuffers() et al + * for the registered framebuffer range, the aperture helpers call + * platform_device_unregister() and the generic driver unloads itself. It + * may not access the device's registers, framebuffer memory, ROM, etc + * afterwards. */ +struct drm_aperture { + struct drm_device *dev; + resource_size_t base; + resource_size_t size; + struct list_head lh; + void (*detach)(struct drm_device *dev); +}; + +static LIST_HEAD(drm_apertures); +static DEFINE_MUTEX(drm_apertures_lock); + +static bool overlap(resource_size_t base1, resource_size_t end1, + resource_size_t base2, resource_size_t end2) +{ + return (base1 < end2) && (end1 > base2); +} + +static void devm_aperture_acquire_release(void *data) +{ + struct drm_aperture *ap = data; + bool detached = !ap->dev; + + if (detached) + return; + + mutex_lock(&drm_apertures_lock); + list_del(&ap->lh); + mutex_unlock(&drm_apertures_lock); +} + +static int devm_aperture_acquire(struct drm_device *dev, + resource_size_t base, resource_size_t size, + void (*detach)(struct drm_device *)) +{ + size_t end = base + size; + struct list_head *pos; + struct drm_aperture *ap; + + mutex_lock(&drm_apertures_lock); + + list_for_each(pos, &drm_apertures) { + ap = container_of(pos, struct drm_aperture, lh); + if (overlap(base, end, ap->base, ap->base + ap->size)) + return -EBUSY; + } + + ap = devm_kzalloc(dev->dev, sizeof(*ap), GFP_KERNEL); + if (!ap) + return -ENOMEM; + + ap->dev = dev; + ap->base = base; + ap->size = size; + ap->detach = detach; + INIT_LIST_HEAD(&ap->lh); + + list_add(&ap->lh, &drm_apertures); + + mutex_unlock(&drm_apertures_lock); + + return devm_add_action_or_reset(dev->dev, devm_aperture_acquire_release, ap); +} + +static void drm_aperture_detach_firmware(struct drm_device *dev) +{ + struct platform_device *pdev = to_platform_device(dev->dev); + + /* + * Remove the device from the device hierarchy. This is the right thing + * to do for firmware-based DRM drivers, such as EFI, VESA or VGA. After + * the new driver takes over the hardware, the firmware device's state + * will be lost. + * + * For non-platform devices, a new callback would be required. + * + * If the aperture helpers ever need to handle native drivers, this call + * would only have to unplug the DRM device, so that the hardware device + * stays around after detachment. + */ + platform_device_unregister(pdev); +} + +/** + * devm_aperture_acquire_from_firmware - Acquires ownership of a firmware framebuffer + * on behalf of a DRM driver. + * @dev: the DRM device to own the framebuffer memory + * @base: the framebuffer's byte offset in physical memory + * @size: the framebuffer size in bytes + * + * Installs the given device as the new owner of the framebuffer. The function + * expects the framebuffer to be provided by a platform device that has been + * set up by firmware. Firmware can be any generic interface, such as EFI, + * VESA, VGA, etc. If the native hardware driver takes over ownership of the + * framebuffer range, the firmware state gets lost. Aperture helpers will then + * unregister the platform device automatically. Acquired apertures are + * released automatically if the underlying device goes away. + * + * The function fails if the framebuffer range, or parts of it, is currently + * owned by another driver. To evict current owners, callers should use + * drm_aperture_remove_conflicting_framebuffers() et al. before calling this + * function. The function also fails if the given device is not a platform + * device. + * + * Returns: + * 0 on success, or a negative errno value otherwise. + */ +int devm_aperture_acquire_from_firmware(struct drm_device *dev, resource_size_t base, + resource_size_t size) +{ + if (drm_WARN_ON(dev, !dev_is_platform(dev->dev))) + return -EINVAL; + + return devm_aperture_acquire(dev, base, size, drm_aperture_detach_firmware); +} +EXPORT_SYMBOL(devm_aperture_acquire_from_firmware); + +static void drm_aperture_detach_drivers(resource_size_t base, resource_size_t size) +{ + resource_size_t end = base + size; + struct list_head *pos, *n; + + mutex_lock(&drm_apertures_lock); + + list_for_each_safe(pos, n, &drm_apertures) { + struct drm_aperture *ap = + container_of(pos, struct drm_aperture, lh); + struct drm_device *dev = ap->dev; + + if (WARN_ON_ONCE(!dev)) + continue; + + if (!overlap(base, end, ap->base, ap->base + ap->size)) + continue; + + ap->dev = NULL; /* detach from device */ + list_del(&ap->lh); + + ap->detach(dev); + } + + mutex_unlock(&drm_apertures_lock); +} + /** * drm_aperture_remove_conflicting_framebuffers - remove existing framebuffers in the given range * @base: the aperture's base address in physical memory @@ -94,10 +295,13 @@ int drm_aperture_remove_conflicting_framebuffers(resource_size_t base, resource_ ret = remove_conflicting_framebuffers(a, name, primary); kfree(a); - return ret; -#else - return 0; + if (ret) + return ret; #endif + + drm_aperture_detach_drivers(base, size); + + return 0; } EXPORT_SYMBOL(drm_aperture_remove_conflicting_framebuffers); @@ -115,7 +319,16 @@ EXPORT_SYMBOL(drm_aperture_remove_conflicting_framebuffers); */ int drm_aperture_remove_conflicting_pci_framebuffers(struct pci_dev *pdev, const char *name) { - int ret = 0; + resource_size_t base, size; + int bar, ret = 0; + + for (bar = 0; bar < PCI_STD_NUM_BARS; ++bar) { + if (!(pci_resource_flags(pdev, bar) & IORESOURCE_MEM)) + continue; + base = pci_resource_start(pdev, bar); + size = pci_resource_len(pdev, bar); + drm_aperture_detach_drivers(base, size); + } /* * WARNING: Apparently we must kick fbdev drivers before vgacon, diff --git a/include/drm/drm_aperture.h b/include/drm/drm_aperture.h index 23cc01647ed3..6c148078780c 100644 --- a/include/drm/drm_aperture.h +++ b/include/drm/drm_aperture.h @@ -5,8 +5,12 @@ #include <linux/types.h> +struct drm_device; struct pci_dev; +int devm_aperture_acquire_from_firmware(struct drm_device *dev, resource_size_t base, + resource_size_t size); + int drm_aperture_remove_conflicting_framebuffers(resource_size_t base, resource_size_t size, bool primary, const char *name); |