diff options
| -rw-r--r-- | Documentation/gpu/drm-internals.rst | 12 | ||||
| -rw-r--r-- | drivers/gpu/drm/Makefile | 2 | ||||
| -rw-r--r-- | drivers/gpu/drm/drm_aperture.c | 114 | ||||
| -rw-r--r-- | include/drm/drm_aperture.h | 31 |
4 files changed, 158 insertions, 1 deletions
diff --git a/Documentation/gpu/drm-internals.rst b/Documentation/gpu/drm-internals.rst index 12272b168580..06af044c882f 100644 --- a/Documentation/gpu/drm-internals.rst +++ b/Documentation/gpu/drm-internals.rst @@ -75,6 +75,18 @@ update it, its value is mostly useless. The DRM core prints it to the kernel log at initialization time and passes it to userspace through the DRM_IOCTL_VERSION ioctl. +Managing Ownership of the Framebuffer Aperture +---------------------------------------------- + +.. kernel-doc:: drivers/gpu/drm/drm_aperture.c + :doc: overview + +.. kernel-doc:: include/drm/drm_aperture.h + :internal: + +.. kernel-doc:: drivers/gpu/drm/drm_aperture.c + :export: + Device Instance and Driver Handling ----------------------------------- diff --git a/drivers/gpu/drm/Makefile b/drivers/gpu/drm/Makefile index 5279db4392df..89e747fedc00 100644 --- a/drivers/gpu/drm/Makefile +++ b/drivers/gpu/drm/Makefile @@ -3,7 +3,7 @@ # Makefile for the drm device driver. This driver provides support for the # Direct Rendering Infrastructure (DRI) in XFree86 4.1.0 and higher. -drm-y := drm_auth.o drm_cache.o \ +drm-y := drm_aperture.o drm_auth.o drm_cache.o \ drm_file.o drm_gem.o drm_ioctl.o drm_irq.o \ drm_drv.o \ drm_sysfs.o drm_hashtab.o drm_mm.o \ diff --git a/drivers/gpu/drm/drm_aperture.c b/drivers/gpu/drm/drm_aperture.c new file mode 100644 index 000000000000..929dcbc0758a --- /dev/null +++ b/drivers/gpu/drm/drm_aperture.c @@ -0,0 +1,114 @@ +// SPDX-License-Identifier: MIT + +#include <drm/drm_aperture.h> +#include <drm/drm_fb_helper.h> + +/** + * DOC: overview + * + * A graphics device might be supported by different drivers, but only one + * driver can be active at any given time. Many systems load a generic + * graphics drivers, such as EFI-GOP or VESA, early during the boot process. + * During later boot stages, they replace the generic driver with a dedicated, + * hardware-specific driver. To take over the device the dedicated driver + * first has to remove the generic driver. DRM aperture functions manage + * ownership of DRM framebuffer memory and hand-over between drivers. + * + * DRM drivers should call drm_aperture_remove_conflicting_framebuffers() + * at the top of their probe function. The function removes any generic + * driver that is currently associated with the given framebuffer memory. + * If the framebuffer is located at PCI BAR 0, the rsp code looks as in the + * example given below. + * + * .. code-block:: c + * + * static int remove_conflicting_framebuffers(struct pci_dev *pdev) + * { + * bool primary = false; + * resource_size_t base, size; + * int ret; + * + * base = pci_resource_start(pdev, 0); + * size = pci_resource_len(pdev, 0); + * #ifdef CONFIG_X86 + * primary = pdev->resource[PCI_ROM_RESOURCE].flags & IORESOURCE_ROM_SHADOW; + * #endif + * + * return drm_aperture_remove_conflicting_framebuffers(base, size, primary, + * "example driver"); + * } + * + * static int probe(struct pci_dev *pdev) + * { + * int ret; + * + * // Remove any generic drivers... + * ret = remove_conflicting_framebuffers(pdev); + * if (ret) + * return ret; + * + * // ... and initialize the hardware. + * ... + * + * drm_dev_register(); + * + * return 0; + * } + * + * PCI device drivers should call + * drm_aperture_remove_conflicting_pci_framebuffers() and let it detect the + * 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. + */ + +/** + * drm_aperture_remove_conflicting_framebuffers - remove existing framebuffers in the given range + * @base: the aperture's base address in physical memory + * @size: aperture size in bytes + * @primary: also kick vga16fb if present + * @name: requesting driver name + * + * This function removes graphics device drivers which use memory range described by + * @base and @size. + * + * Returns: + * 0 on success, or a negative errno code otherwise + */ +int drm_aperture_remove_conflicting_framebuffers(resource_size_t base, resource_size_t size, + bool primary, const char *name) +{ + struct apertures_struct *a; + int ret; + + a = alloc_apertures(1); + if (!a) + return -ENOMEM; + + a->ranges[0].base = base; + a->ranges[0].size = size; + + ret = drm_fb_helper_remove_conflicting_framebuffers(a, name, primary); + kfree(a); + + return ret; +} +EXPORT_SYMBOL(drm_aperture_remove_conflicting_framebuffers); + +/** + * drm_aperture_remove_conflicting_pci_framebuffers - remove existing framebuffers for PCI devices + * @pdev: PCI device + * @name: requesting driver name + * + * This function removes graphics device drivers using memory range configured + * for any of @pdev's memory bars. The function assumes that PCI device with + * shadowed ROM drives a primary display and so kicks out vga16fb. + * + * Returns: + * 0 on success, or a negative errno code otherwise + */ +int drm_aperture_remove_conflicting_pci_framebuffers(struct pci_dev *pdev, const char *name) +{ + return drm_fb_helper_remove_conflicting_pci_framebuffers(pdev, name); +} +EXPORT_SYMBOL(drm_aperture_remove_conflicting_pci_framebuffers); diff --git a/include/drm/drm_aperture.h b/include/drm/drm_aperture.h new file mode 100644 index 000000000000..23cc01647ed3 --- /dev/null +++ b/include/drm/drm_aperture.h @@ -0,0 +1,31 @@ +/* SPDX-License-Identifier: MIT */ + +#ifndef _DRM_APERTURE_H_ +#define _DRM_APERTURE_H_ + +#include <linux/types.h> + +struct pci_dev; + +int drm_aperture_remove_conflicting_framebuffers(resource_size_t base, resource_size_t size, + bool primary, const char *name); + +int drm_aperture_remove_conflicting_pci_framebuffers(struct pci_dev *pdev, const char *name); + +/** + * drm_aperture_remove_framebuffers - remove all existing framebuffers + * @primary: also kick vga16fb if present + * @name: requesting driver name + * + * This function removes all graphics device drivers. Use this function on systems + * that can have their framebuffer located anywhere in memory. + * + * Returns: + * 0 on success, or a negative errno code otherwise + */ +static inline int drm_aperture_remove_framebuffers(bool primary, const char *name) +{ + return drm_aperture_remove_conflicting_framebuffers(0, (resource_size_t)-1, primary, name); +} + +#endif |