[linux] Provide ACPI settings via /sys/firmware/acpi/tables

Signed-off-by: Michael Brown <mcb30@ipxe.org>

src/config/defaults/linux.h

@@ -21,6 +21,7 @@ FILE_LICENCE ( GPL2_OR_LATER );
 #define REBOOT_NULL
 #define PCIAPI_LINUX
 #define DMAAPI_FLAT
+#define ACPI_LINUX
 
 #define DRIVERS_LINUX
 

src/include/ipxe/acpi.h

@@ -360,6 +360,7 @@ extern userptr_t acpi_find_via_rsdt ( uint32_t signature, unsigned int index );
 /* Include all architecture-independent ACPI API headers */
 #include <ipxe/null_acpi.h>
 #include <ipxe/efi/efi_acpi.h>
+#include <ipxe/linux/linux_acpi.h>
 
 /* Include all architecture-dependent ACPI API headers */
 #include <bits/acpi.h>

src/include/ipxe/linux/linux_acpi.h

@@ -0,0 +1,18 @@
+#ifndef _IPXE_LINUX_ACPI_H
+#define _IPXE_LINUX_ACPI_H
+
+/** @file
+ *
+ * iPXE ACPI API for Linux
+ *
+ */
+
+FILE_LICENCE ( GPL2_OR_LATER_OR_UBDL );
+
+#ifdef ACPI_LINUX
+#define ACPI_PREFIX_linux
+#else
+#define ACPI_PREFIX_linux __linux_
+#endif
+
+#endif /* _IPXE_LINUX_ACPI_H */

src/interface/linux/linux_acpi.c

@@ -0,0 +1,173 @@
+/*
+ * 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.h>
+#include <ipxe/list.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 */
+	void *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 */ ];
+	ssize_t rlen;
+	size_t len;
+	void *data;
+	int fd;
+
+	/* Check for existing table */
+	list_for_each_entry ( table, &linux_acpi_tables, list ) {
+		if ( ( table->signature == signature ) &&
+		     ( table->index == index ) )
+			return virt_to_user ( table->data );
+	}
+
+	/* Allocate a new table */
+	table = malloc ( sizeof ( *table ) );
+	if ( ! table )
+		goto err_alloc;
+	table->signature = signature;
+	table->index = index;
+
+	/* Construct filename */
+	memset ( &u, 0, sizeof ( u ) );
+	u.signature = le32_to_cpu ( signature );
+	snprintf ( filename, sizeof ( filename ), "%s%s%d", prefix,
+		   u.filename, ( index + 1 ) );
+
+	/* Open file */
+	fd = linux_open ( filename, O_RDONLY );
+	if ( ( fd < 0 ) && ( index == 0 ) ) {
+		filename[ sizeof ( prefix ) - 1 /* NUL */ +
+			  4 /* signature */ ] = '\0';
+		fd = linux_open ( filename, O_RDONLY );
+	}
+	if ( fd < 0 ) {
+		DBGC ( &linux_acpi_tables, "ACPI could not open %s: %s\n",
+		       filename, linux_strerror ( linux_errno ) );
+		goto err_open;
+	}
+
+	/* Read header */
+	rlen = linux_read ( fd, &header, sizeof ( header ) );
+	if ( rlen < 0 ) {
+		DBGC ( &linux_acpi_tables, "ACPI could not read %s header: "
+		       "%s\n", filename, linux_strerror ( linux_errno ) );
+		goto err_header;
+	}
+	if ( ( ( size_t ) rlen ) != sizeof ( header ) ) {
+		DBGC ( &linux_acpi_tables, "ACPI underlength %s header\n",
+		       filename );
+		goto err_header_len;
+	}
+
+	/* Parse header */
+	len = le32_to_cpu ( header.length );
+	if ( len < sizeof ( header ) ) {
+		DBGC ( &linux_acpi_tables, "ACPI malformed %s header\n",
+		       filename );
+		goto err_malformed;
+	}
+
+	/* Allocate data */
+	table->data = malloc ( len );
+	if ( ! table->data )
+		goto err_data;
+
+	/* Read table */
+	memcpy ( table->data, &header, sizeof ( header ) );
+	data = ( table->data + sizeof ( header ) );
+	len -= sizeof ( header );
+	while ( len ) {
+		rlen = linux_read ( fd, data, len );
+		if ( rlen < 0 ) {
+			DBGC ( &linux_acpi_tables, "ACPI could not read %s: "
+			       "%s\n", filename,
+			       linux_strerror ( linux_errno ) );
+			goto err_body;
+		}
+		if ( rlen == 0 ) {
+			DBGC ( &linux_acpi_tables, "ACPI underlength %s\n",
+			       filename );
+			goto err_body_len;
+		}
+		data += rlen;
+		len -= rlen;
+	}
+
+	/* Close file */
+	linux_close ( fd );
+
+	/* Add to list of tables */
+	list_add ( &table->list, &linux_acpi_tables );
+	DBGC ( &linux_acpi_tables, "ACPI cached %s\n", filename );
+
+	return virt_to_user ( table->data );
+
+ err_body_len:
+ err_body:
+	free ( table->data );
+ err_data:
+ err_malformed:
+ err_header_len:
+ err_header:
+	linux_close ( fd );
+ err_open:
+	free ( table );
+ err_alloc:
+	return UNULL;
+}
+
+PROVIDE_ACPI ( linux, acpi_find, linux_acpi_find );