1 // SPDX-License-Identifier: MIT
4 #include <linux/device.h>
19  * A graphics device might be supported by different drivers, but only one
21  * graphics drivers, such as EFI-GOP or VESA, early during the boot process.
23  * hardware-specific driver. To take over the device, the dedicated driver
25  * ownership of framebuffer memory and hand-over between drivers.
30  * An example for a graphics device on the platform bus is shown below.
32  * .. code-block:: c
42  *			return -ENODEV;
43  *		base = mem->start;
61  * The given example reads the platform device's I/O-memory range from the
62  * device instance. An active framebuffer will be located within this range.
66  * the device.
68  * While the given example uses a platform device, the aperture helpers work
70  * device drivers can also call aperture_remove_conflicting_pci_devices() and
71  * let the function detect the apertures automatically. Device drivers without
82  * .. code-block:: c
91  *			return -ENODEV;
92  *		base = mem->start;
107  *		// Hot-unplug the device
129  * Once hot unplugged from hardware, it may not access the device's
134 	struct device *dev;
138 	void (*detach)(struct device *dev);
153 	bool detached = !ap->dev;  in devm_aperture_acquire_release()
159 	list_del(&ap->lh);  in devm_aperture_acquire_release()
163 static int devm_aperture_acquire(struct device *dev,  in devm_aperture_acquire()
165 				 void (*detach)(struct device *))  in devm_aperture_acquire()  argument
175 		if (overlap(base, end, ap->base, ap->base + ap->size)) {  in devm_aperture_acquire()
177 			return -EBUSY;  in devm_aperture_acquire()
184 		return -ENOMEM;  in devm_aperture_acquire()
187 	ap->dev = dev;  in devm_aperture_acquire()
188 	ap->base = base;  in devm_aperture_acquire()
189 	ap->size = size;  in devm_aperture_acquire()
190 	ap->detach = detach;  in devm_aperture_acquire()
191 	INIT_LIST_HEAD(&ap->lh);  in devm_aperture_acquire()
193 	list_add(&ap->lh, &apertures);  in devm_aperture_acquire()
200 static void aperture_detach_platform_device(struct device *dev)  in aperture_detach_platform_device()
205 	 * Remove the device from the device hierarchy. This is the right thing  in aperture_detach_platform_device()
206 	 * to do for firmware-based fb drivers, such as EFI, VESA or VGA. After  in aperture_detach_platform_device()
207 	 * the new driver takes over the hardware, the firmware device's state  in aperture_detach_platform_device()
210 	 * For non-platform devices, a new callback would be required.  in aperture_detach_platform_device()
213 	 * would only have to unplug the DRM device, so that the hardware device  in aperture_detach_platform_device()
220  * devm_aperture_acquire_for_platform_device - Acquires ownership of an aperture
221  *                                             on behalf of a platform device.
222  * @pdev:	the platform device to own the aperture
226  * Installs the given device as the new owner of the aperture. The function
227  * expects the aperture to be provided by a platform device. If another
229  * unregister the platform device automatically. All acquired apertures are
230  * released automatically when the underlying device goes away.
233  * owned by another device. To evict current owners, callers should use
243 	return devm_aperture_acquire(&pdev->dev, base, size, aperture_detach_platform_device);  in devm_aperture_acquire_for_platform_device()
256 		struct device *dev = ap->dev;  in aperture_detach_devices()
261 		if (!overlap(base, end, ap->base, ap->base + ap->size))  in aperture_detach_devices()
264 		ap->dev = NULL; /* detach from device */  in aperture_detach_devices()
265 		list_del(&ap->lh);  in aperture_detach_devices()
267 		ap->detach(dev);  in aperture_detach_devices()
274  * aperture_remove_conflicting_devices - remove devices in the given range
288 	 * If a driver asked to unregister a platform device registered by  in aperture_remove_conflicting_devices()
307  * __aperture_remove_legacy_vga_devices - remove legacy VGA devices of a PCI devices
308  * @pdev: PCI device
311  * framebuffer or a console. This is useful if you have a VGA-compatible
312  * PCI graphics device with framebuffers in non-BAR locations. Drivers
342  * aperture_remove_conflicting_pci_devices - remove existing framebuffers for PCI devices
343  * @pdev: PCI device
347  * memory bars. The function assumes that PCI device with shadowed ROM
348  * drives a primary display and therefore kicks out vga16fb as well.
355 	bool primary = false;  in aperture_remove_conflicting_pci_devices()  local
361 		primary = true;  in aperture_remove_conflicting_pci_devices()
363 	if (primary)  in aperture_remove_conflicting_pci_devices()
377 	 * If this is the primary adapter, there could be a VGA device  in aperture_remove_conflicting_pci_devices()
379 	 * device as well.  in aperture_remove_conflicting_pci_devices()
381 	if (primary)  in aperture_remove_conflicting_pci_devices()