Adding upstream version 6.6.15.upstream/6.6.15

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 192 insertions, 0 deletions

diff --git a/drivers/gpu/drm/drm_aperture.c b/drivers/gpu/drm/drm_aperture.c
new file mode 100644
index 0000000000..5729f3bb43
--- /dev/null
+++ b/drivers/gpu/drm/drm_aperture.c
@@ -0,0 +1,192 @@
+// SPDX-License-Identifier: MIT
+
+#include <linux/aperture.h>
+#include <linux/platform_device.h>
+
+#include <drm/drm_aperture.h>
+#include <drm/drm_drv.h>
+#include <drm/drm_print.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 const struct drm_driver example_driver = {
+ *		...
+ *	};
+ *
+ *	static int remove_conflicting_framebuffers(struct pci_dev *pdev)
+ *	{
+ *		resource_size_t base, size;
+ *		int ret;
+ *
+ *		base = pci_resource_start(pdev, 0);
+ *		size = pci_resource_len(pdev, 0);
+ *
+ *		return drm_aperture_remove_conflicting_framebuffers(base, size,
+ *		                                                    &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.
+ *
+ * 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 achieved
+ * 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 owned 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.
+ */
+
+/**
+ * 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)
+{
+	struct platform_device *pdev;
+
+	if (drm_WARN_ON(dev, !dev_is_platform(dev->dev)))
+		return -EINVAL;
+
+	pdev = to_platform_device(dev->dev);
+
+	return devm_aperture_acquire_for_platform_device(pdev, base, size);
+}
+EXPORT_SYMBOL(devm_aperture_acquire_from_firmware);
+
+/**
+ * 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
+ * @req_driver: requesting DRM driver
+ *
+ * This function removes graphics device drivers which use the 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,
+						 const struct drm_driver *req_driver)
+{
+	return aperture_remove_conflicting_devices(base, size, req_driver->name);
+}
+EXPORT_SYMBOL(drm_aperture_remove_conflicting_framebuffers);
+
+/**
+ * drm_aperture_remove_conflicting_pci_framebuffers - remove existing framebuffers for PCI devices
+ * @pdev: PCI device
+ * @req_driver: requesting DRM driver
+ *
+ * This function removes graphics device drivers using the memory range configured
+ * for any of @pdev's memory bars. The function assumes that a 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 struct drm_driver *req_driver)
+{
+	return aperture_remove_conflicting_pci_devices(pdev, req_driver->name);
+}
+EXPORT_SYMBOL(drm_aperture_remove_conflicting_pci_framebuffers);