drm/i915: Add intel_bo_panic_setup() and intel_bo_panic_finish()

Implement both functions for i915 and xe, they prepare the work for
drm_panic support.
They both use kmap_try_from_panic(), and map one page at a time, to
write the panic screen on the framebuffer.

Signed-off-by: Jocelyn Falempe <jfalempe@redhat.com>
Link: https://lore.kernel.org/r/20250624091501.257661-8-jfalempe@redhat.com
Signed-off-by: Maarten Lankhorst <dev@lankhorst.se>

1 files changed, 64 insertions, 0 deletions

diff --git a/drivers/gpu/drm/xe/display/intel_bo.c b/drivers/gpu/drm/xe/display/intel_bo.c
index 926fcd9c86e1..bbb504f8e242 100644
--- a/drivers/gpu/drm/xe/display/intel_bo.c
+++ b/drivers/gpu/drm/xe/display/intel_bo.c
@@ -1,8 +1,11 @@
 // SPDX-License-Identifier: MIT
 /* Copyright © 2024 Intel Corporation */
 
+#include <drm/drm_cache.h>
 #include <drm/drm_gem.h>
+#include <drm/drm_panic.h>
 
+#include "intel_fb.h"
 #include "intel_display_types.h"
 
 #include "xe_bo.h"
@@ -73,6 +76,50 @@ struct xe_framebuffer {
 	struct xe_panic_data panic;
 };
 
+static inline struct xe_panic_data *to_xe_panic_data(struct intel_framebuffer *fb)
+{
+	return &container_of_const(fb, struct xe_framebuffer, base)->panic;
+}
+
+static void xe_panic_kunmap(struct xe_panic_data *panic)
+{
+	if (panic->vaddr) {
+		drm_clflush_virt_range(panic->vaddr, PAGE_SIZE);
+		kunmap_local(panic->vaddr);
+		panic->vaddr = NULL;
+	}
+}
+
+/*
+ * The scanout buffer pages are not mapped, so for each pixel,
+ * use kmap_local_page_try_from_panic() to map the page, and write the pixel.
+ * Try to keep the map from the previous pixel, to avoid too much map/unmap.
+ */
+static void xe_panic_page_set_pixel(struct drm_scanout_buffer *sb, unsigned int x,
+				    unsigned int y, u32 color)
+{
+	struct intel_framebuffer *fb = (struct intel_framebuffer *)sb->private;
+	struct xe_panic_data *panic = to_xe_panic_data(fb);
+	struct xe_bo *bo = gem_to_xe_bo(intel_fb_bo(&fb->base));
+	unsigned int new_page;
+	unsigned int offset;
+
+	offset = y * sb->pitch[0] + x * sb->format->cpp[0];
+
+	new_page = offset >> PAGE_SHIFT;
+	offset = offset % PAGE_SIZE;
+	if (new_page != panic->page) {
+		xe_panic_kunmap(panic);
+		panic->page = new_page;
+		panic->vaddr = ttm_bo_kmap_try_from_panic(&bo->ttm,
+							  panic->page);
+	}
+	if (panic->vaddr) {
+		u32 *pix = panic->vaddr + offset;
+		*pix = color;
+	}
+}
+
 struct intel_framebuffer *intel_bo_alloc_framebuffer(void)
 {
 	struct xe_framebuffer *xe_fb;
@@ -83,3 +130,20 @@ struct intel_framebuffer *intel_bo_alloc_framebuffer(void)
 	return NULL;
 }
 
+int intel_bo_panic_setup(struct drm_scanout_buffer *sb)
+{
+	struct intel_framebuffer *fb = (struct intel_framebuffer *)sb->private;
+	struct xe_panic_data *panic = to_xe_panic_data(fb);
+
+	panic->page = -1;
+	sb->set_pixel = xe_panic_page_set_pixel;
+	return 0;
+}
+
+void intel_bo_panic_finish(struct intel_framebuffer *fb)
+{
+	struct xe_panic_data *panic = to_xe_panic_data(fb);
+
+	xe_panic_kunmap(panic);
+	panic->page = -1;
+}