/* SPDX-License-Identifier: GPL-2.0 or MIT */ /* * Copyright (c) 2024 Intel * Copyright (c) 2024 Red Hat */ #ifndef __DRM_PANIC_H__#define __DRM_PANIC_H__ #include <linux/module.h>#include <linux/types.h>#include <linux/iosys-map.h> #include <drm/drm_device.h>#include <drm/drm_fourcc.h> /** * struct drm_scanout_buffer - DRM scanout buffer * * This structure holds the information necessary for drm_panic to draw the * panic screen, and display it. */struct drm_scanout_buffer {	/**	 * @format:	 *	 * drm format of the scanout buffer.	 */	const struct drm_format_info *format; 	/**	 * @map:	 *	 * Virtual address of the scanout buffer, either in memory or iomem.	 * The scanout buffer should be in linear format, and can be directly	 * sent to the display hardware. Tearing is not an issue for the panic	 * screen.	 */	struct iosys_map map[DRM_FORMAT_MAX_PLANES]; 	/**	 * @width: Width of the scanout buffer, in pixels.	 */	unsigned int width; 	/**	 * @height: Height of the scanout buffer, in pixels.	 */	unsigned int height; 	/**	 * @pitch: Length in bytes between the start of two consecutive lines.	 */	unsigned int pitch[DRM_FORMAT_MAX_PLANES]; 	/**	 * @set_pixel: Optional function, to set a pixel color on the	 * framebuffer. It allows to handle special tiling format inside the	 * driver.	 */	void (*set_pixel)(struct drm_scanout_buffer *sb, unsigned int x,			  unsigned int y, u32 color); }; #ifdef CONFIG_DRM_PANIC /** * drm_panic_trylock - try to enter the panic printing critical section * @dev: struct drm_device * @flags: unsigned long irq flags you need to pass to the unlock() counterpart * * This function must be called by any panic printing code. The panic printing * attempt must be aborted if the trylock fails. * * Panic printing code can make the following assumptions while holding the * panic lock: * * - Anything protected by drm_panic_lock() and drm_panic_unlock() pairs is safe *   to access. * * - Furthermore the panic printing code only registers in drm_dev_unregister() *   and gets removed in drm_dev_unregister(). This allows the panic code to *   safely access any state which is invariant in between these two function *   calls, like the list of planes &drm_mode_config.plane_list or most of the *   struct drm_plane structure. * * Specifically thanks to the protection around plane updates in * drm_atomic_helper_swap_state() the following additional guarantees hold: * * - It is safe to deference the drm_plane.state pointer. * * - Anything in struct drm_plane_state or the driver's subclass thereof which *   stays invariant after the atomic check code has finished is safe to access. *   Specifically this includes the reference counted pointers to framebuffer *   and buffer objects. * * - Anything set up by &drm_plane_helper_funcs.fb_prepare and cleaned up *   &drm_plane_helper_funcs.fb_cleanup is safe to access, as long as it stays *   invariant between these two calls. This also means that for drivers using *   dynamic buffer management the framebuffer is pinned, and therefer all *   relevant datastructures can be accessed without taking any further locks *   (which would be impossible in panic context anyway). * * - Importantly, software and hardware state set up by *   &drm_plane_helper_funcs.begin_fb_access and *   &drm_plane_helper_funcs.end_fb_access is not safe to access. * * Drivers must not make any assumptions about the actual state of the hardware, * unless they explicitly protected these hardware access with drm_panic_lock() * and drm_panic_unlock(). * * Return: * %0 when failing to acquire the raw spinlock, nonzero on success. */#define drm_panic_trylock(dev, flags) \	raw_spin_trylock_irqsave(&(dev)->mode_config.panic_lock, flags) /** * drm_panic_lock - protect panic printing relevant state * @dev: struct drm_device * @flags: unsigned long irq flags you need to pass to the unlock() counterpart * * This function must be called to protect software and hardware state that the * panic printing code must be able to rely on. The protected sections must be * as small as possible. It uses the irqsave/irqrestore variant, and can be * called from irq handler. Examples include: * * - Access to peek/poke or other similar registers, if that is the way the *   driver prints the pixels into the scanout buffer at panic time. * * - Updates to pointers like &drm_plane.state, allowing the panic handler to *   safely deference these. This is done in drm_atomic_helper_swap_state(). * * - An state that isn't invariant and that the driver must be able to access *   during panic printing. */ #define drm_panic_lock(dev, flags) \	raw_spin_lock_irqsave(&(dev)->mode_config.panic_lock, flags) /** * drm_panic_unlock - end of the panic printing critical section * @dev: struct drm_device * @flags: irq flags that were returned when acquiring the lock * * Unlocks the raw spinlock acquired by either drm_panic_lock() or * drm_panic_trylock(). */#define drm_panic_unlock(dev, flags) \	raw_spin_unlock_irqrestore(&(dev)->mode_config.panic_lock, flags) #else static inline bool drm_panic_trylock(struct drm_device *dev, unsigned long flags){	return true;} static inline void drm_panic_lock(struct drm_device *dev, unsigned long flags) {}static inline void drm_panic_unlock(struct drm_device *dev, unsigned long flags) {} #endif #endif /* __DRM_PANIC_H__ */