drm/xe: Add support for OOB workarounds

There are WAs that, due to their nature, cannot be applied from a
central place like xe_wa.c. Those are peppered around the rest of the
code, as needed. Now they have a new name:  "out-of-band workarounds".

These workarounds have their names and rules still grouped in xe_wa.c,
inside the xe_wa_oob array, which is generated at compile time by
xe_wa_oob.rules and the hostprog xe_gen_wa_oob. The code generation
guarantees that the header xe_wa_oob.h contains the IDs for the
workarounds that match the index in the table. This way the runtime
checks that are spread throughout the code are simple tests against the
bitmap saved during initialization.

v2: Fix prev_name tracking not working when it's empty, i.e. when there
    is more than 1 continuation rule.

Reviewed-by: Matt Roper <matthew.d.roper@intel.com>
Link: https://lore.kernel.org/r/20230526164358.86393-13-lucas.demarchi@intel.com
Signed-off-by: Lucas De Marchi <lucas.demarchi@intel.com>
Signed-off-by: Rodrigo Vivi <rodrigo.vivi@intel.com>

drivers/gpu/drm/xe/.gitignore

@@ -1,2 +1,4 @@
 # SPDX-License-Identifier: GPL-2.0-only
 *.hdrtest
+/generated
+/xe_gen_wa_oob

drivers/gpu/drm/xe/Makefile

@@ -29,6 +29,19 @@ CFLAGS_xe_pci.o = $(call cc-disable-warning, override-init)
 
 subdir-ccflags-y += -I$(obj) -I$(srctree)/$(src)
 
+# generated sources
+hostprogs := xe_gen_wa_oob
+
+generated_oob := $(obj)/generated/xe_wa_oob.c $(obj)/generated/xe_wa_oob.h
+
+quiet_cmd_wa_oob = GEN     $(notdir $(generated_oob))
+      cmd_wa_oob = mkdir -p $(@D); $^ $(generated_oob)
+
+$(generated_oob) &: $(obj)/xe_gen_wa_oob $(srctree)/$(src)/xe_wa_oob.rules
+	$(call cmd,wa_oob)
+
+$(obj)/xe_wa.o: $(generated_oob)
+
 # Please keep these build lists sorted!
 
 # core driver code

drivers/gpu/drm/xe/xe_gen_wa_oob.c

@@ -0,0 +1,165 @@
+// SPDX-License-Identifier: MIT
+/*
+ * Copyright © 2023 Intel Corporation
+ */
+
+#define _GNU_SOURCE
+#include <ctype.h>
+#include <errno.h>
+#include <stdbool.h>
+#include <stdio.h>
+#include <string.h>
+
+#define HEADER \
+	"// SPDX-License-Identifier: MIT\n" \
+	"\n" \
+	"/*\n" \
+	" * DO NOT MODIFY.\n" \
+	" *\n" \
+	" * This file was generated from rules: %s\n" \
+	" */\n" \
+	"#ifndef _GENERATED_XE_WA_OOB_\n" \
+	"#define _GENERATED_XE_WA_OOB_\n" \
+	"\n" \
+	"enum {\n"
+
+#define FOOTER \
+	"};\n" \
+	"\n" \
+	"#endif\n"
+
+static void print_usage(FILE *f)
+{
+	fprintf(f, "usage: %s <input-rule-file> <generated-c-source-file> <generated-c-header-file>\n",
+		program_invocation_short_name);
+}
+
+static void print_parse_error(const char *err_msg, const char *line,
+			      unsigned int lineno)
+{
+	fprintf(stderr, "ERROR: %s\nERROR: %u: %.60s\n",
+		err_msg, lineno, line);
+}
+
+static char *strip(char *line, size_t linelen)
+{
+	while (isspace(*(line + linelen)))
+		linelen--;
+
+	line[linelen - 1] = '\0';
+
+	return  line + strspn(line, " \f\n\r\t\v");
+}
+
+#define MAX_LINE_LEN 4096
+static int parse(FILE *input, FILE *csource, FILE *cheader)
+{
+	char line[MAX_LINE_LEN + 1];
+	char *name, *prev_name = NULL, *rules;
+	unsigned int lineno = 0, idx = 0;
+
+	while (fgets(line, sizeof(line), input)) {
+		size_t linelen;
+		bool is_continuation;
+
+		if (line[0] == '\0' || line[0] == '#' || line[0] == '\n') {
+			lineno++;
+			continue;
+		}
+
+		linelen = strlen(line);
+		if (linelen == MAX_LINE_LEN) {
+			print_parse_error("line too long", line, lineno);
+			return -EINVAL;
+		}
+
+		is_continuation = isspace(line[0]);
+		name = strip(line, linelen);
+
+		if (!is_continuation) {
+			name = strtok(name, " \t");
+			rules = strtok(NULL, "");
+		} else {
+			if (!prev_name) {
+				print_parse_error("invalid rule continuation",
+						  line, lineno);
+				return -EINVAL;
+			}
+
+			rules = name;
+			name = NULL;
+		}
+
+		if (rules[0] == '\0') {
+			print_parse_error("invalid empty rule\n", line, lineno);
+			return -EINVAL;
+		}
+
+		if (name) {
+			fprintf(cheader, "\tXE_WA_OOB_%s = %u,\n", name, idx);
+			fprintf(csource, "{ XE_RTP_NAME(\"%s\"), XE_RTP_RULES(%s) },\n",
+				name, rules);
+		} else {
+			fprintf(csource, "{ XE_RTP_NAME(NULL), XE_RTP_RULES(%s) },\n",
+				rules);
+		}
+
+		idx++;
+		lineno++;
+		if (!is_continuation)
+			prev_name = name;
+	}
+
+	fprintf(cheader, "\t_XE_WA_OOB_COUNT = %u\n", idx);
+
+	return 0;
+}
+
+int main(int argc, const char *argv[])
+{
+	enum {
+		ARGS_INPUT,
+		ARGS_CSOURCE,
+		ARGS_CHEADER,
+		_ARGS_COUNT
+	};
+	struct {
+		const char *fn;
+		const char *mode;
+		FILE *f;
+	} args[] = {
+		[ARGS_INPUT] = { .fn = argv[1], .mode = "r" },
+		[ARGS_CSOURCE] = { .fn = argv[2], .mode = "w" },
+		[ARGS_CHEADER] = { .fn = argv[3], .mode = "w" },
+	};
+	int ret = 1;
+
+	if (argc < 3) {
+		fprintf(stderr, "ERROR: wrong arguments\n");
+		print_usage(stderr);
+		return 1;
+	}
+
+	for (int i = 0; i < _ARGS_COUNT; i++) {
+		args[i].f = fopen(args[i].fn, args[i].mode);
+		if (!args[i].f) {
+			fprintf(stderr, "ERROR: Can't open %s: %m\n",
+				args[i].fn);
+			goto err;
+		}
+	}
+
+	fprintf(args[ARGS_CHEADER].f, HEADER, args[ARGS_INPUT].fn);
+	ret = parse(args[ARGS_INPUT].f, args[ARGS_CSOURCE].f,
+		    args[ARGS_CHEADER].f);
+	if (!ret)
+		fprintf(args[ARGS_CHEADER].f, FOOTER);
+
+err:
+	for (int i = 0; i < _ARGS_COUNT; i++) {
+		if (args[i].f)
+			fclose(args[i].f);
+	}
+
+	return ret;
+}

drivers/gpu/drm/xe/xe_gt.c

@@ -321,6 +321,7 @@ int xe_gt_init_early(struct xe_gt *gt)
 		return err;
 
 	xe_wa_process_gt(gt);
+	xe_wa_process_oob(gt);
 	xe_tuning_process_gt(gt);
 
 	return 0;

drivers/gpu/drm/xe/xe_gt_types.h

@@ -368,6 +368,8 @@ struct xe_gt {
 		unsigned long *engine;
 		/** @lrc: bitmap with active LRC workarounds */
 		unsigned long *lrc;
+		/** @oob: bitmap with active OOB workaroudns */
+		unsigned long *oob;
 	} wa_active;
 };
 

drivers/gpu/drm/xe/xe_wa.c

@@ -9,6 +9,7 @@
 #include <kunit/visibility.h>
 #include <linux/compiler_types.h>
 
+#include "generated/xe_wa_oob.h"
 #include "regs/xe_engine_regs.h"
 #include "regs/xe_gt_regs.h"
 #include "regs/xe_regs.h"
@@ -73,8 +74,8 @@
  *      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
@@ -579,8 +580,31 @@ static const struct xe_rtp_entry_sr lrc_was[] = {
 	{}
 };
 
+static __maybe_unused const struct xe_rtp_entry oob_was[] = {
+#include <generated/xe_wa_oob.c>
+	{}
+};
+
+static_assert(ARRAY_SIZE(oob_was) - 1 == _XE_WA_OOB_COUNT);
+
 __diag_pop();
 
+/**
+ * xe_wa_process_oob - process OOB workaround table
+ * @gt: GT instance to process workarounds for
+ *
+ * Process OOB workaround table for this platform, marking in @gt the
+ * workarounds that are active.
+ */
+void xe_wa_process_oob(struct xe_gt *gt)
+{
+	struct xe_rtp_process_ctx ctx = XE_RTP_PROCESS_CTX_INITIALIZER(gt);
+
+	xe_rtp_process_ctx_enable_active_tracking(&ctx, gt->wa_active.oob,
+						  ARRAY_SIZE(oob_was));
+	xe_rtp_process(&ctx, oob_was);
+}
+
 /**
  * xe_wa_process_gt - process GT workaround table
  * @gt: GT instance to process workarounds for
@@ -641,13 +665,14 @@ void xe_wa_process_lrc(struct xe_hw_engine *hwe)
 int xe_wa_init(struct xe_gt *gt)
 {
 	struct xe_device *xe = gt_to_xe(gt);
-	size_t n_lrc, n_engine, n_gt, total;
+	size_t n_oob, n_lrc, n_engine, n_gt, total;
 	unsigned long *p;
 
 	n_gt = BITS_TO_LONGS(ARRAY_SIZE(gt_was));
 	n_engine = BITS_TO_LONGS(ARRAY_SIZE(engine_was));
 	n_lrc = BITS_TO_LONGS(ARRAY_SIZE(lrc_was));
-	total = n_gt + n_engine + n_lrc;
+	n_oob = BITS_TO_LONGS(ARRAY_SIZE(oob_was));
+	total = n_gt + n_engine + n_lrc + n_oob;
 
 	p = drmm_kzalloc(&xe->drm, sizeof(*p) * total, GFP_KERNEL);
 	if (!p)
@@ -658,6 +683,8 @@ int xe_wa_init(struct xe_gt *gt)
 	gt->wa_active.engine = p;
 	p += n_engine;
 	gt->wa_active.lrc = p;
+	p += n_lrc;
+	gt->wa_active.oob = p;
 
 	return 0;
 }
@@ -677,4 +704,9 @@ void xe_wa_dump(struct xe_gt *gt, struct drm_printer *p)
 	drm_printf(p, "\nLRC Workarounds\n");
 	for_each_set_bit(idx, gt->wa_active.lrc, ARRAY_SIZE(lrc_was))
 		drm_printf_indent(p, 1, "%s\n", lrc_was[idx].name);
+
+	drm_printf(p, "\nOOB Workarounds\n");
+	for_each_set_bit(idx, gt->wa_active.oob, ARRAY_SIZE(oob_was))
+		if (oob_was[idx].name)
+			drm_printf_indent(p, 1, "%s\n", oob_was[idx].name);
 }

drivers/gpu/drm/xe/xe_wa.h

@@ -11,6 +11,7 @@ struct xe_gt;
 struct xe_hw_engine;
 
 int xe_wa_init(struct xe_gt *gt);
+void xe_wa_process_oob(struct xe_gt *gt);
 void xe_wa_process_gt(struct xe_gt *gt);
 void xe_wa_process_engine(struct xe_hw_engine *hwe);
 void xe_wa_process_lrc(struct xe_hw_engine *hwe);
@@ -18,4 +19,12 @@ void xe_wa_process_lrc(struct xe_hw_engine *hwe);
 void xe_reg_whitelist_process_engine(struct xe_hw_engine *hwe);
 void xe_wa_dump(struct xe_gt *gt, struct drm_printer *p);
 
+/**
+ * XE_WA - Out-of-band workarounds, that don't fit the lifecycle any
+ *         other more specific type
+ * @gt__: gt instance
+ * @id__: XE_OOB_<id__>, as generated by build system in generated/xe_wa_oob.h
+ */
+#define XE_WA(gt__, id__) test_bit(XE_WA_OOB_ ## id__, (gt__)->wa_active.oob)
+
 #endif