[Intel-xe] [RFC 2/2] drm/xe: Register OOB workarounds

[Lucas De Marchi]

Some workarounds can't be implemented in the xe_wa.c as entries
on a table since they need to be spread throughout the driver.
Provide a mechanism to allow "registering" these workarounds so they can
later be dumped together with the others.

This uses a trick to define the static const entry when checking if the
workarounds is "enabled". That entry is put in a specific section so
later we can access all the entries in that section. Normally the linker
provides the __start_<section>/__stop_<section> symbols. However since
the kernel itself uses a linker script, this doesn't work, hence provide
our own custom linker script to do what is missing.

Signed-off-by: Lucas De Marchi <lucas.demarchi at intel.com>
---
 drivers/gpu/drm/xe/Makefile       |  2 ++
 drivers/gpu/drm/xe/xe.lds         |  8 ++++++++
 drivers/gpu/drm/xe/xe_guc.c       |  6 +++---
 drivers/gpu/drm/xe/xe_rtp_types.h |  8 ++++++++
 drivers/gpu/drm/xe/xe_wa.c        | 14 ++++++++++++--
 drivers/gpu/drm/xe/xe_wa.h        | 10 ++++++++++
 6 files changed, 43 insertions(+), 5 deletions(-)
 create mode 100644 drivers/gpu/drm/xe/xe.lds

diff --git a/drivers/gpu/drm/xe/Makefile b/drivers/gpu/drm/xe/Makefile
index aceca651de57..9cbcc0ed06b2 100644
--- a/drivers/gpu/drm/xe/Makefile
+++ b/drivers/gpu/drm/xe/Makefile
@@ -216,6 +216,8 @@ ifeq ($(CONFIG_DRM_FBDEV_EMULATION),y)
 	xe-$(CONFIG_DRM_XE_DISPLAY) += display/intel_fbdev.o
 endif
 
+LDFLAGS_xe.o := -T $(srctree)/$(src)/xe.lds
+
 obj-$(CONFIG_DRM_XE) += xe.o
 obj-$(CONFIG_DRM_XE_KUNIT_TEST) += tests/
 
diff --git a/drivers/gpu/drm/xe/xe.lds b/drivers/gpu/drm/xe/xe.lds
new file mode 100644
index 000000000000..a2187eab2c8b
--- /dev/null
+++ b/drivers/gpu/drm/xe/xe.lds
@@ -0,0 +1,8 @@
+SECTIONS
+{
+    .rodata.__xe_wa_oob	ALIGN(8) : {
+        __start___xe_wa_oob = .;
+        *(__xe_wa_oob)
+        __stop___xe_wa_oob = .;
+    }
+}
diff --git a/drivers/gpu/drm/xe/xe_guc.c b/drivers/gpu/drm/xe/xe_guc.c
index ee71b969bcbf..608ac2a022e8 100644
--- a/drivers/gpu/drm/xe/xe_guc.c
+++ b/drivers/gpu/drm/xe/xe_guc.c
@@ -20,6 +20,7 @@
 #include "xe_mmio.h"
 #include "xe_platform_types.h"
 #include "xe_uc_fw.h"
+#include "xe_wa.h"
 #include "xe_wopcm.h"
 
 static struct xe_gt *
@@ -134,9 +135,8 @@ static u32 guc_ctl_wa_flags(struct xe_guc *guc)
 	struct xe_gt *gt = guc_to_gt(guc);
 	u32 flags = 0;
 
-	/* Wa_22012773006:gen11,gen12 < XeHP */
-	if (GRAPHICS_VER(xe) >= 11 &&
-	    GRAPHICS_VERx100(xe) < 1250)
+	if (XE_WA("22012773006",
+		  GRAPHICS_VER(xe) >= 11 && GRAPHICS_VERx100(xe) < 1250))
 		flags |= GUC_WA_POLLCS;
 
 	/* Wa_16011759253 */
diff --git a/drivers/gpu/drm/xe/xe_rtp_types.h b/drivers/gpu/drm/xe/xe_rtp_types.h
index e87f1b280d96..4f7832d074bd 100644
--- a/drivers/gpu/drm/xe/xe_rtp_types.h
+++ b/drivers/gpu/drm/xe/xe_rtp_types.h
@@ -101,4 +101,12 @@ struct xe_rtp_entry {
 	u8 flags;
 };
 
+/**
+ * struct xe_rtp_entry - Entry in a special section, used for "out-of-band"
+ *			 definitions
+ */
+struct xe_rtp_oob_entry {
+	const char *name;
+};
+
 #endif
diff --git a/drivers/gpu/drm/xe/xe_wa.c b/drivers/gpu/drm/xe/xe_wa.c
index 100315c03014..26fb91aae014 100644
--- a/drivers/gpu/drm/xe/xe_wa.c
+++ b/drivers/gpu/drm/xe/xe_wa.c
@@ -72,8 +72,8 @@
  *      engine registers are restored in a context restore sequence. This is
  *      currently not used in the driver.
  *
- * - Other:  There are WAs that, due to their nature, cannot be applied from a
- *   central place. Those are peppered around the rest of the code, as needed.
+ * - Other/OOB:  There are WAs that, due to their nature, cannot be applied from
+ *   a central place. Those are peppered around the rest of the code, as needed.
  *   Workarounds related to the display IP are the main example.
  *
  * .. [1] Technically, some registers are powercontext saved & restored, so they
@@ -92,6 +92,9 @@
 #define _MMIO(x)	_XE_RTP_REG(x)
 #define MCR_REG(x)	_XE_RTP_MCR_REG(x)
 
+extern const struct xe_rtp_oob_entry __start___xe_wa_oob[];
+extern const struct xe_rtp_oob_entry __stop___xe_wa_oob[];
+
 __diag_push();
 __diag_ignore_all("-Woverride-init", "Allow field overrides in table");
 
@@ -665,6 +668,7 @@ void xe_wa_process_lrc(struct xe_hw_engine *hwe)
 void xe_wa_dump(struct xe_device *xe, struct drm_printer *p)
 {
 	const struct xe_rtp_entry *entry;
+	const struct xe_rtp_oob_entry *oob_entry;
 
 	drm_printf(p, "Workarounds\n");
 
@@ -679,4 +683,10 @@ void xe_wa_dump(struct xe_device *xe, struct drm_printer *p)
 	drm_printf(p, "\tLRC\n");
 	for (entry = lrc_was; entry && entry->name; entry++)
 		drm_printf(p, "\t\t%s\n", entry->name);
+
+	drm_printf(p, "\tOOB\n");
+	for (oob_entry = __start___xe_wa_oob;
+	     oob_entry < __stop___xe_wa_oob;
+	     oob_entry++)
+		drm_printf(p, "\t\t%s\n", oob_entry->name);
 }
diff --git a/drivers/gpu/drm/xe/xe_wa.h b/drivers/gpu/drm/xe/xe_wa.h
index 97d104b7e566..212fc9b4efe6 100644
--- a/drivers/gpu/drm/xe/xe_wa.h
+++ b/drivers/gpu/drm/xe/xe_wa.h
@@ -6,6 +6,8 @@
 #ifndef _XE_WA_
 #define _XE_WA_
 
+#include "xe_rtp_types.h"
+
 struct drm_printer;
 struct xe_device;
 struct xe_gt;
@@ -19,4 +21,12 @@ void xe_wa_dump(struct xe_device *xe, struct drm_printer *p);
 
 void xe_reg_whitelist_process_engine(struct xe_hw_engine *hwe);
 
+#define XE_WA(name__, cond__) ({					\
+	static const struct xe_rtp_oob_entry entry__			\
+	__used __aligned(8) __section("__xe_wa_oob") = {		\
+		.name = name__,						\
+	};								\
+	cond__;								\
+})
+
 #endif
-- 
2.39.0