1 files changed, 148 insertions, 0 deletions
diff --git a/src/interface/linux/linux_acpi.c b/src/interface/linux/linux_acpi.c
new file mode 100644
index 000000000..e658936f2
--- /dev/null
+++ b/src/interface/linux/linux_acpi.c
@@ -0,0 +1,148 @@
+/*
+ * Copyright (C) 2021 Michael Brown <mbrown@fensystems.co.uk>.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License as
+ * published by the Free Software Foundation; either version 2 of the
+ * License, or any later version.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
+ * 02110-1301, USA.
+ */
+
+FILE_LICENCE ( GPL2_OR_LATER );
+
+#include <stdlib.h>
+#include <stdio.h>
+#include <errno.h>
+#include <ipxe/linux_api.h>
+#include <ipxe/linux_sysfs.h>
+#include <ipxe/linux.h>
+#include <ipxe/list.h>
+#include <ipxe/init.h>
+#include <ipxe/umalloc.h>
+#include <ipxe/acpi.h>
+
+/** ACPI sysfs directory */
+#define ACPI_SYSFS_PREFIX "/sys/firmware/acpi/tables/"
+
+/** A cached ACPI table */
+struct linux_acpi_table {
+	/** List of cached tables */
+	struct list_head list;
+	/** Signature */
+	uint32_t signature;
+	/** Index */
+	unsigned int index;
+	/** Cached data */
+	userptr_t data;
+};
+
+/** List of cached ACPI tables */
+static LIST_HEAD ( linux_acpi_tables );
+
+/**
+ * Locate ACPI table
+ *
+ * @v signature		Requested table signature
+ * @v index		Requested index of table with this signature
+ * @ret table		Table, or UNULL if not found
+ */
+static userptr_t linux_acpi_find ( uint32_t signature, unsigned int index ) {
+	struct linux_acpi_table *table;
+	struct acpi_header *header;
+	union {
+		uint32_t signature;
+		char filename[5];
+	} u;
+	static const char prefix[] = ACPI_SYSFS_PREFIX;
+	char filename[ sizeof ( prefix ) - 1 /* NUL */ + 4 /* signature */
+		       + 3 /* "999" */ + 1 /* NUL */ ];
+	int len;
+	int rc;
+
+	/* Check for existing table */
+	list_for_each_entry ( table, &linux_acpi_tables, list ) {
+		if ( ( table->signature == signature ) &&
+		     ( table->index == index ) )
+			return table->data;
+	}
+
+	/* Allocate a new table */
+	table = malloc ( sizeof ( *table ) );
+	if ( ! table )
+		goto err_alloc;
+	table->signature = signature;
+	table->index = index;
+
+	/* Construct filename (including numeric suffix) */
+	memset ( &u, 0, sizeof ( u ) );
+	u.signature = le32_to_cpu ( signature );
+	snprintf ( filename, sizeof ( filename ), "%s%s%d", prefix,
+		   u.filename, ( index + 1 ) );
+
+	/* Read file (with or without numeric suffix for index 0) */
+	len = linux_sysfs_read ( filename, &table->data );
+	if ( ( len < 0 ) && ( index == 0 ) ) {
+		filename[ sizeof ( prefix ) - 1 /* NUL */ +
+			  4 /* signature */ ] = '\0';
+		len = linux_sysfs_read ( filename, &table->data );
+	}
+	if ( len < 0 ) {
+		rc = len;
+		DBGC ( &linux_acpi_tables, "ACPI could not read %s: %s\n",
+		       filename, strerror ( rc ) );
+		goto err_read;
+	}
+	header = user_to_virt ( table->data, 0 );
+	if ( ( ( ( size_t ) len ) < sizeof ( *header ) ) ||
+	     ( ( ( size_t ) len ) < le32_to_cpu ( header->length ) ) ) {
+		rc = -ENOENT;
+		DBGC ( &linux_acpi_tables, "ACPI underlength %s (%d bytes)\n",
+		       filename, len );
+		goto err_len;
+	}
+
+	/* Add to list of tables */
+	list_add ( &table->list, &linux_acpi_tables );
+	DBGC ( &linux_acpi_tables, "ACPI cached %s\n", filename );
+
+	return table->data;
+
+ err_len:
+	ufree ( table->data );
+ err_read:
+	free ( table );
+ err_alloc:
+	return UNULL;
+}
+
+/**
+ * Free cached ACPI data
+ *
+ */
+static void linux_acpi_shutdown ( int booting __unused ) {
+	struct linux_acpi_table *table;
+	struct linux_acpi_table *tmp;
+
+	list_for_each_entry_safe ( table, tmp, &linux_acpi_tables, list ) {
+		list_del ( &table->list );
+		ufree ( table->data );
+		free ( table );
+	}
+}
+
+/** ACPI shutdown function */
+struct startup_fn linux_acpi_startup_fn __startup_fn ( STARTUP_NORMAL ) = {
+	.name = "linux_acpi",
+	.shutdown = linux_acpi_shutdown,
+};
+
+PROVIDE_ACPI ( linux, acpi_find, linux_acpi_find );