acpi: Add PPTT support

This patch adds code to generate Processor Properties
Topology Tables (PPTT) compliant to the ACPI 6.4 specification.

 - The 'acpi_get_pptt_topology' hook is mandatory once ACPI_PPTT
 is selected. Its purpose is to return a pointer to a topology tree,
 which describes the relationship between CPUs and caches. The hook
 can be provided by, for example, mainboard code.

Background: We are currently working on mainboard code for qemu-sbsa
and Neoverse N2. Both require a valid PPTT table. Patch was tested
against the qemu-sbsa board.

Change-Id: Ia119e1ba15756704668116bdbc655190ec94ff10
Signed-off-by: David Milosevic <David.Milosevic@9elements.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/78071
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Arthur Heymans <arthur@aheymans.xyz>
Reviewed-by: Lean Sheng Tan <sheng.tan@9elements.com>

src/acpi/Kconfig

@@ -91,3 +91,17 @@ config MAX_ACPI_TABLE_SIZE_KB
 	default 144
 	help
 	  Set the maximum size of all ACPI tables in KiB.
+
+config ACPI_PPTT
+	bool
+	depends on HAVE_ACPI_TABLES
+	help
+	  Selected to build an ACPI Processor Properties Topology Table.
+
+config ACPI_PPTT_MAX_CACHES
+	int
+	depends on ACPI_PPTT
+	default 4
+	help
+	  This variable sets the maximum number of distinct caches per
+	  topology level. Increasing this option also increases stack usage.

src/acpi/Makefile.inc

@@ -8,6 +8,7 @@ ramstage-y += acpi_apic.c
 ramstage-y += acpi_dmar.c
 ramstage-y += acpi_hpet.c
 endif
+ramstage-$(CONFIG_ACPI_PPTT) += acpi_pptt.c
 ramstage-y += acpigen.c
 ramstage-y += acpigen_dptf.c
 ramstage-y += acpigen_dsm.c

src/acpi/acpi.c

@@ -1204,6 +1204,18 @@ unsigned long acpi_create_lpi_desc_ncst(acpi_lpi_desc_ncst_t *lpi_desc, uint16_t
 	return lpi_desc->header.length;
 }
 
+static void acpi_create_pptt(acpi_header_t *header, void *unused)
+{
+	if (!CONFIG(ACPI_PPTT))
+		return;
+
+	if (acpi_fill_header(header, "PPTT", PPTT, sizeof(acpi_pptt_t)) != CB_SUCCESS)
+		return;
+
+	acpi_pptt_t *pptt = (acpi_pptt_t *)header;
+	acpi_create_pptt_body(pptt);
+}
+
 static uint8_t acpi_spcr_type(void)
 {
 	/* 16550-compatible with parameters defined in Generic Address Structure */
@@ -1394,6 +1406,7 @@ unsigned long write_acpi_tables(const unsigned long start)
 		{ acpi_create_bert, NULL, sizeof(acpi_bert_t) },
 		{ acpi_create_spcr, NULL, sizeof(acpi_spcr_t) },
 		{ acpi_create_gtdt, NULL, sizeof(acpi_gtdt_t) },
+		{ acpi_create_pptt, NULL, sizeof(acpi_pptt_t) },
 	};
 
 	current = start;
@@ -1743,6 +1756,8 @@ int get_acpi_table_revision(enum acpi_tables table)
 		return 4;
 	case GTDT:
 		return 3;
+	case PPTT: /* ACPI 6.4 */
+		return 3;
 	default:
 		return -1;
 	}

src/acpi/acpi_pptt.c

@@ -0,0 +1,186 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+
+#include <acpi/acpi.h>
+#include <include/assert.h>
+#include <console/console.h>
+
+/*
+ * A structure to hold a cache pointer
+ * and its corresponding reference within
+ * the PPTT table.
+ */
+struct cache_reference {
+	struct pptt_cache *cache; // cache pointer
+	u32                ref;   // and its reference within PPTT
+};
+
+/*
+ * A list of 'struct cache_reference', used
+ * to keep track of generated caches per topology level.
+ */
+struct cache_list {
+	u32                    n_caches;                                // number of caches in list
+	struct cache_reference cache_refs[CONFIG_ACPI_PPTT_MAX_CACHES]; // cache reference list
+};
+
+/*
+ * Start of the PPTT table. Constant
+ * value as soon as we enter acpi_create_pptt_body.
+ */
+static uintptr_t pptt_start;
+
+/* --- Helper Functions (non exposed) --- */
+
+static inline u32 node_to_reference(const void *node)
+{
+	/*
+	 * References are the offset from the start
+	 * of the PPTT table.
+	 *
+	 *    PPTT
+	 * +---------+ <- pptt_start (acpi_pptt_t) <---+
+	 * |         |                                 | node - pptt_start
+	 * |         |                                 |
+	 * +---------+ <- node (cpu or cache) <--------+
+	 * |         |
+	 * |         |
+	 * |         |
+	 * +---------+
+	 */
+	return ((uintptr_t)node - pptt_start);
+}
+
+static u32 count_resources(struct pptt_cpu_resources *res)
+{
+	u32 n_resources = 0;
+
+	while (res != NULL) {
+		n_resources += 1;
+		res = res->next;
+	}
+
+	return n_resources;
+}
+
+static u32 cache_list_ref_of(struct cache_list *cache_list, const struct pptt_cache *cache)
+{
+	/*
+	 * Lookup the PPTT reference of 'cache'.
+	 * Return 0, if no PPTT structure exists for 'cache'.
+	 */
+
+	for (int i = 0; i < cache_list->n_caches; i++) {
+		if (cache_list->cache_refs[i].cache == cache)
+			return cache_list->cache_refs[i].ref;
+	}
+
+	/* no cache reference found */
+	return 0;
+}
+
+static inline void cache_list_append(struct cache_list *cache_list, struct pptt_cache *cache, const u32 ref)
+{
+	printk(BIOS_DEBUG, "acpi: pptt: cache=%p ref=%u\n", cache, ref);
+
+	cache_list->cache_refs[cache_list->n_caches].cache = cache;
+	cache_list->cache_refs[cache_list->n_caches].ref   = ref;
+
+	cache_list->n_caches += 1;
+}
+
+static u32 new_pptt_cache(unsigned long *current, struct pptt_cache *cache, struct cache_list *cache_list)
+{
+	static u32 unique_cache_id = 1;
+	u32 current_reference      = 0;
+
+	if ((current_reference = cache_list_ref_of(cache_list, cache)) != 0)
+		return current_reference;
+
+	if (cache_list->n_caches >= CONFIG_ACPI_PPTT_MAX_CACHES) {
+		printk(BIOS_WARNING, "acpi: pptt: Too many distinct caches! PPTT incomplete.\n");
+		return 0;
+	}
+
+	acpi_pptt_cache_node_t *cache_node = (acpi_pptt_cache_node_t *)*current;
+	memset(cache_node, 0x0, sizeof(acpi_pptt_cache_node_t));
+
+	cache_node->type   = PPTT_NODE_TYPE_CACHE;
+	cache_node->length = sizeof(acpi_pptt_cache_node_t);
+
+	cache_node->flags         = cache->flags.raw;
+	cache_node->size          = cache->size;
+	cache_node->n_sets        = cache->numsets;
+	cache_node->associativity = cache->associativity;
+
+	cache_node->attributes = cache->attributes;
+	cache_node->line_size  = cache->line_size;
+	cache_node->cache_id   = unique_cache_id++;
+
+	*current += cache_node->length;
+
+	current_reference = node_to_reference(cache_node);
+	cache_list_append(cache_list, cache, current_reference);
+
+	if (cache->next_level != NULL)
+		cache_node->next_level = new_pptt_cache(current, cache->next_level, cache_list);
+
+	return current_reference;
+}
+
+static u32 new_pptt_cpu(unsigned long *current, const struct pptt_topology *cpu, const u32 parent_ref, struct cache_list *cache_list)
+{
+	acpi_pptt_cpu_node_t *cpu_node = (acpi_pptt_cpu_node_t *)*current;
+
+	const u32 n_resources      = count_resources(cpu->resources);
+	const u32 structure_length = sizeof(acpi_pptt_cpu_node_t) + (n_resources * sizeof(u32));
+
+	memset(cpu_node, 0x0, structure_length);
+
+	cpu_node->type         = PPTT_NODE_TYPE_CPU;
+	cpu_node->length       = structure_length;
+	cpu_node->flags        = cpu->flags.raw;
+	cpu_node->processor_id = cpu->processor_id;
+	cpu_node->parent       = parent_ref;
+
+	*current += cpu_node->length;
+
+	for (struct pptt_cpu_resources *it = cpu->resources; it != NULL; it = it->next)
+		cpu_node->resources[cpu_node->n_resources++] = new_pptt_cache(current, it->cache, cache_list);
+
+	return node_to_reference(cpu_node);
+}
+
+static void setup_topology(const struct pptt_topology *node, const u32 parent_ref, unsigned long *current)
+{
+	struct cache_list cache_list = {
+		.cache_refs = { },
+		.n_caches   = 0
+	};
+
+	while (node != NULL) {
+		const u32 cpu_ref = new_pptt_cpu(current, node, parent_ref, &cache_list);
+		setup_topology(node->child, cpu_ref, current);
+
+		node = node->sibling;
+	}
+}
+
+/* --- PPTT generation helper functions (exposed) --- */
+
+void acpi_create_pptt_body(acpi_pptt_t *pptt)
+{
+	/* set start of pptt table */
+	pptt_start = (uintptr_t)pptt;
+
+	/* locate start of pptt body */
+	unsigned long current = (unsigned long)(pptt->body);
+
+	/* retrieve processor topology */
+	const struct pptt_topology *topology_tree = acpi_get_pptt_topology();
+
+	/* write processor properties topology table to memory */
+	setup_topology(topology_tree, 0, &current);
+
+	/* update length field in pptt header */
+	pptt->header.length = current - (unsigned long)pptt;
+}