[PATCH v4 12/14] drm/panic: Internalize panic locking in DRM core and helpers

[Thomas Zimmermann <tzimmermann@suse.de>]

None of the DRM drivers handles panic locking. Declare the interfaces
in an internal header file. Move the trylock required during the panic
into the DRM core's sources.

Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
Reviewed-by: Jocelyn Falempe <jfalempe@redhat.com>
---
 Documentation/gpu/drm-kms.rst        |  3 ++
 MAINTAINERS                          |  3 +-
 drivers/gpu/drm/drm_atomic_helper.c  |  2 +-
 drivers/gpu/drm/drm_drv.c            |  2 +-
 drivers/gpu/drm/drm_panic.c          |  4 ++
 drivers/gpu/drm/drm_panic_internal.h | 55 +++++++++++++++++++++++
 include/drm/drm_panic.h              | 65 ----------------------------
 7 files changed, 66 insertions(+), 68 deletions(-)
 create mode 100644 drivers/gpu/drm/drm_panic_internal.h

diff --git a/Documentation/gpu/drm-kms.rst b/Documentation/gpu/drm-kms.rst
index 0dd440a14946..8988fd64369b 100644
--- a/Documentation/gpu/drm-kms.rst
+++ b/Documentation/gpu/drm-kms.rst
@@ -421,6 +421,9 @@ Plane Panic Functions Reference
 .. kernel-doc:: include/drm/drm_panic.h
    :internal:
 
+.. kernel-doc:: drivers/gpu/drm/drm_panic_internal.h
+   :internal:
+
 .. kernel-doc:: drivers/gpu/drm/drm_panic.c
    :export:
 
diff --git a/MAINTAINERS b/MAINTAINERS
index 2e01cc9ff176..eb7ee0bfc6af 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -9124,7 +9124,8 @@ S:	Supported
 T:	git https://gitlab.freedesktop.org/drm/misc/kernel.git
 F:	drivers/gpu/drm/drm_draw.c
 F:	drivers/gpu/drm/drm_draw_internal.h
-F:	drivers/gpu/drm/drm_panic*.c
+F:	drivers/gpu/drm/drm_panic.c
+F:	drivers/gpu/drm/drm_panic_internal.h
 F:	drivers/gpu/drm/tests/drm_panic_test.c
 F:	include/drm/drm_panic.h
 F:	include/drm/drm_panic_helper.h
diff --git a/drivers/gpu/drm/drm_atomic_helper.c b/drivers/gpu/drm/drm_atomic_helper.c
index 285aac3554df..af3934df3313 100644
--- a/drivers/gpu/drm/drm_atomic_helper.c
+++ b/drivers/gpu/drm/drm_atomic_helper.c
@@ -41,7 +41,6 @@
 #include <drm/drm_drv.h>
 #include <drm/drm_framebuffer.h>
 #include <drm/drm_gem_atomic_helper.h>
-#include <drm/drm_panic.h>
 #include <drm/drm_print.h>
 #include <drm/drm_self_refresh_helper.h>
 #include <drm/drm_vblank.h>
@@ -49,6 +48,7 @@
 
 #include "drm_crtc_helper_internal.h"
 #include "drm_crtc_internal.h"
+#include "drm_panic_internal.h"
 
 /**
  * DOC: overview
diff --git a/drivers/gpu/drm/drm_drv.c b/drivers/gpu/drm/drm_drv.c
index 8c0879c336e5..64055514acbf 100644
--- a/drivers/gpu/drm/drm_drv.c
+++ b/drivers/gpu/drm/drm_drv.c
@@ -51,13 +51,13 @@
 #include <drm/drm_file.h>
 #include <drm/drm_managed.h>
 #include <drm/drm_mode_object.h>
-#include <drm/drm_panic.h>
 #include <drm/drm_print.h>
 #include <drm/drm_privacy_screen_machine.h>
 #include <drm/drm_ras_genl_family.h>
 
 #include "drm_crtc_internal.h"
 #include "drm_internal.h"
+#include "drm_panic_internal.h"
 
 MODULE_AUTHOR("Gareth Hughes, Leif Delgass, José Fonseca, Jon Smirl");
 MODULE_DESCRIPTION("DRM shared core routines");
diff --git a/drivers/gpu/drm/drm_panic.c b/drivers/gpu/drm/drm_panic.c
index 2bb172231dd0..4836e974f86d 100644
--- a/drivers/gpu/drm/drm_panic.c
+++ b/drivers/gpu/drm/drm_panic.c
@@ -35,6 +35,7 @@
 
 #include "drm_crtc_internal.h"
 #include "drm_draw_internal.h"
+#include "drm_panic_internal.h"
 
 MODULE_AUTHOR("Jocelyn Falempe");
 MODULE_DESCRIPTION("DRM panic handler");
@@ -975,6 +976,9 @@ int drm_plane_helper_display_panic_screen(struct drm_plane *plane, const char *d
 }
 EXPORT_SYMBOL(drm_plane_helper_display_panic_screen);
 
+#define drm_panic_trylock(dev, flags) \
+	raw_spin_trylock_irqsave(&(dev)->mode_config.panic_lock, flags)
+
 static void drm_panic_display_panic_screen(struct drm_plane *plane, const char *description)
 {
 #if defined(CONFIG_DRM_PANIC_FOREGROUND_COLOR)
diff --git a/drivers/gpu/drm/drm_panic_internal.h b/drivers/gpu/drm/drm_panic_internal.h
new file mode 100644
index 000000000000..c68d64c56e15
--- /dev/null
+++ b/drivers/gpu/drm/drm_panic_internal.h
@@ -0,0 +1,55 @@
+/* SPDX-License-Identifier: GPL-2.0 or MIT */
+
+/*
+ * Copyright (c) 2024 Intel
+ * Copyright (c) 2024 Red Hat
+ */
+
+#ifndef __DRM_PANIC_INTERNAL_H__
+#define __DRM_PANIC_INTERNAL_H__
+
+#include <linux/spinlock.h>
+
+struct drm_device;
+
+#ifdef CONFIG_DRM_PANIC
+
+/**
+ * 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 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_INTERNAL_H__ */
diff --git a/include/drm/drm_panic.h b/include/drm/drm_panic.h
index 430df536de14..99572b7eeab9 100644
--- a/include/drm/drm_panic.h
+++ b/include/drm/drm_panic.h
@@ -8,11 +8,9 @@
 #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 page;
@@ -85,71 +83,8 @@ struct drm_scanout_buffer {
 	 * set_pixel()
 	 */
 	void *private;
-
 };
 
-#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
- *
- * The panic-printing code calls this function. The panic printing attempt must
- * be aborted if the trylock fails.
- *
- * 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
-
 #if defined(CONFIG_DRM_PANIC_SCREEN_QR_CODE)
 size_t drm_panic_qr_max_data_size(u8 version, size_t url_len);
 
-- 
2.55.0