acpi: Add a linker list for ACPI tables

At present we call lots of functions to generate the required ACPI tables.
It would be better to standardise these functions and allow them to be
automatically collected and used when needed.

Add a linker list to handle this.

Signed-off-by: Simon Glass <sjg@chromium.org>

include/dm/acpi.h

@@ -27,6 +27,8 @@
 
 #if !defined(__ACPI__)
 
+#include <linker_lists.h>
+
 struct nhlt;
 struct udevice;
 
@@ -68,6 +70,48 @@ struct acpi_ctx {
 	int ltop;
 };
 
+/**
+ * enum acpi_writer_flags_t - flags to use for the ACPI writers
+ */
+enum acpi_writer_flags_t {
+	ACPIWF_ALIGN64_,
+};
+
+struct acpi_writer;
+
+/**
+ * acpi_writer_func() - Function that can write an ACPI table
+ *
+ * @ctx: ACPI context to use for writing
+ * @entry: Linker-list entry for this writer
+ * @return 0 if OK, -ve on error
+ */
+typedef int (*acpi_writer_func)(struct acpi_ctx *ctx,
+				const struct acpi_writer *entry);
+
+/**
+ * struct acpi_writer - an ACPI table that can be written
+ *
+ * @name: Name of the writer
+ * @table: Table name that is generated (e.g. "DSDT")
+ * @h_write: Writer function
+ */
+struct acpi_writer {
+	const char *name;
+	const char *table;
+	acpi_writer_func h_write;
+	int flags;
+};
+
+/* Declare a new ACPI table writer */
+#define ACPI_WRITER(_name, _table, _write, _flags)					\
+	ll_entry_declare(struct acpi_writer, _name, acpi_writer) = {	\
+		.name = #_name,						\
+		.table = _table,					\
+		.h_write = _write,					\
+		.flags = _flags,					\
+	}
+
 /**
  * struct acpi_ops - ACPI operations supported by driver model
  */
@@ -240,6 +284,19 @@ int acpi_get_path(const struct udevice *dev, char *out_path, int maxlen);
  */
 void acpi_reset_items(void);
 
+/**
+ * acpi_write_one() - Call a single ACPI writer entry
+ *
+ * This handles aligning the context afterwards, if the entry flags indicate
+ * that.
+ *
+ * @ctx: ACPI context to use
+ * @entry: Entry to call
+ * @return 0 if OK, -ENOENT if this writer produced an empty entry, other -ve
+ * value on error
+ */
+int acpi_write_one(struct acpi_ctx *ctx, const struct acpi_writer *entry);
+
 #endif /* __ACPI__ */
 
 #endif

lib/acpi/acpi_writer.c

@@ -0,0 +1,91 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * Handles writing the declared ACPI tables
+ *
+ * Copyright 2021 Google LLC
+ */
+
+#define LOG_CATEGORY LOGC_ACPI
+
+#include <common.h>
+#include <log.h>
+#include <malloc.h>
+#include <mapmem.h>
+#include <acpi/acpi_table.h>
+#include <asm/global_data.h>
+#include <dm/acpi.h>
+
+DECLARE_GLOBAL_DATA_PTR;
+
+int acpi_write_one(struct acpi_ctx *ctx, const struct acpi_writer *entry)
+{
+	int ret;
+
+	log_debug("%s: writing table '%s'\n", entry->name,
+		  entry->table);
+	ctx->tab_start = ctx->current;
+	ret = entry->h_write(ctx, entry);
+	if (ret == -ENOENT) {
+		log_debug("%s: Omitted due to being empty\n",
+			  entry->name);
+		ret = 0;
+		ctx->current = ctx->tab_start;	/* drop the table */
+		return ret;
+	}
+	if (ret)
+		return log_msg_ret("write", ret);
+
+	acpi_align(ctx);
+
+	return 0;
+}
+
+static int acpi_write_all(struct acpi_ctx *ctx)
+{
+	const struct acpi_writer *writer =
+		 ll_entry_start(struct acpi_writer, acpi_writer);
+	const int n_ents = ll_entry_count(struct acpi_writer, acpi_writer);
+	const struct acpi_writer *entry;
+	int ret;
+
+	for (entry = writer; entry != writer + n_ents; entry++) {
+		ret = acpi_write_one(ctx, entry);
+		if (ret && ret != -ENOENT)
+			return log_msg_ret("one", ret);
+	}
+
+	return 0;
+}
+
+/*
+ * QEMU's version of write_acpi_tables is defined in drivers/misc/qfw.c
+ */
+ulong write_acpi_tables(ulong start_addr)
+{
+	struct acpi_ctx *ctx;
+	ulong addr;
+	void *start;
+	int ret;
+
+	ctx = calloc(1, sizeof(*ctx));
+	if (!ctx)
+		return log_msg_ret("mem", -ENOMEM);
+	gd->acpi_ctx = ctx;
+
+	start = map_sysmem(start_addr, 0);
+
+	log_debug("ACPI: Writing ACPI tables at %lx\n", start_addr);
+
+	acpi_reset_items();
+
+	ret = acpi_write_all(ctx);
+	if (ret) {
+		log_err("Failed to write ACPI tables (err=%d)\n", ret);
+		return log_msg_ret("write", -ENOMEM);
+	}
+
+	addr = map_to_sysmem(ctx->current);
+	log_debug("ACPI current = %lx\n", addr);
+
+	return addr;
+}