Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756874AbcCaJnk (ORCPT ); Thu, 31 Mar 2016 05:43:40 -0400 Received: from mga09.intel.com ([134.134.136.24]:61946 "EHLO mga09.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756607AbcCaJhp (ORCPT ); Thu, 31 Mar 2016 05:37:45 -0400 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.24,421,1455004800"; d="scan'208";a="945123440" From: Octavian Purdila To: "Rafael J. Wysocki" , Len Brown , Matt Fleming , Mark Brown , Wolfram Sang Cc: Joel Becker , Christoph Hellwig , linux-acpi@vger.kernel.org, linux-efi@vger.kernel.org, linux-i2c@vger.kernel.org, linux-spi@vger.kernel.org, linux-kernel@vger.kernel.org, irina.tirdea@intel.com, Octavian Purdila Subject: [RFC PATCH 02/10] acpi: install SSDT tables from initrd Date: Thu, 31 Mar 2016 12:36:58 +0300 Message-Id: <1459417026-6697-3-git-send-email-octavian.purdila@intel.com> X-Mailer: git-send-email 1.9.1 In-Reply-To: <1459417026-6697-1-git-send-email-octavian.purdila@intel.com> References: <1459417026-6697-1-git-send-email-octavian.purdila@intel.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 6493 Lines: 204 This patch allows loading user defined SSDTs from the first, uncompressed, initrd. The SSDT aml code must be stored in files under the /kernel/firmware/acpi/overlay path. Signed-off-by: Octavian Purdila --- Documentation/acpi/ssdt-overlays.txt | 94 ++++++++++++++++++++++++++++++++++++ drivers/acpi/bus.c | 63 ++++++++++++++++++++++++ 2 files changed, 157 insertions(+) create mode 100644 Documentation/acpi/ssdt-overlays.txt diff --git a/Documentation/acpi/ssdt-overlays.txt b/Documentation/acpi/ssdt-overlays.txt new file mode 100644 index 0000000..a94c3f9 --- /dev/null +++ b/Documentation/acpi/ssdt-overlays.txt @@ -0,0 +1,94 @@ + +In order to support ACPI open-ended hardware configurations (e.g. development +boards) we need a way to augment the ACPI configuration provided by the firmware +image. A common example is connecting sensors on I2C / SPI buses on development +boards. + +Although this can be accomplished by creating a kernel platform driver or +recompiling the firmware image with updated ACPI tables, neither is practical: +the former proliferates board specific kernel code while the latter requires +access to firmware tools which are often not publicly available. + +Because ACPI supports external references in AML code a more practical +way to augment firmware ACPI configuration is by dynamically loading +user defined SSDT tables that contain the board specific information. + +For example, to enumerate a Bosch BMA222E accelerometer on the I2C bus of the +Minnowboard MAX development board exposed via the LSE connector [1], the +following ASL code can be used: + +DefinitionBlock ("minnowmax.aml", "SSDT", 1, "Vendor", "Accel", 0x00000003) +{ + External (\_SB.I2C6, DeviceObj) + + Scope (\_SB.I2C6) + { + Device (STAC) + { + Name (_ADR, Zero) + Name (_HID, "BMA222E") + + Method (_CRS, 0, Serialized) + { + Name (RBUF, ResourceTemplate () + { + I2cSerialBus (0x0018, ControllerInitiated, 0x00061A80, + AddressingMode7Bit, "\\_SB.I2C6", 0x00, + ResourceConsumer, ,) + GpioInt (Edge, ActiveHigh, Exclusive, PullDown, 0x0000, + "\\_SB.GPO2", 0x00, ResourceConsumer, , ) + { // Pin list + 0 + } + }) + Return (RBUF) + } + } + } +} + +which can then be compiled to AML binary format: + +$ iasl minnowmax.asl + +Intel ACPI Component Architecture +ASL Optimizing Compiler version 20140214-64 [Mar 29 2014] +Copyright (c) 2000 - 2014 Intel Corporation + +ASL Input: minnomax.asl - 30 lines, 614 bytes, 7 keywords +AML Output: minnowmax.aml - 165 bytes, 6 named objects, 1 executable opcodes + +[1] http://wiki.minnowboard.org/MinnowBoard_MAX#Low_Speed_Expansion_Connector_.28Top.29 + +The resulting AML code can then be loaded by the kernel using one of the methods +below. + +== Loading ACPI SSDTs from initrd == + +This option allows loading of user defined SSDTs from initrd and it is useful +when the system does not support EFI or when there is not enough EFI storage. + +It works in a similar way with initrd based ACPI tables overrides: SSDT aml code +must be placed in the first, uncompressed, initrd under the +"kernel/firmware/acpi/overlay" path. We use a different path than the initrd +tables override to avoid conflicts with the override feature. + +Multiple files can be used and this will translate in loading multiple +tables. Only tables with the SSDT signature will be loaded. + +Here is an example: + +# Add the raw ACPI tables to an uncompressed cpio archive. +# They must be put into a /kernel/firmware/acpi/overlay directory inside the +# cpio archive. +# The uncompressed cpio archive must be the first. +# Other, typically compressed cpio archives, must be +# concatenated on top of the uncompressed one. +mkdir -p kernel/firmware/acpi +cp ssdt.aml kernel/firmware/acpi + +# Create the uncompressed cpio archive and concatenate the original initrd +# on top: +find kernel | cpio -H newc --create > /boot/instrumented_initrd +cat /boot/initrd >>/boot/instrumented_initrd + diff --git a/drivers/acpi/bus.c b/drivers/acpi/bus.c index 891c42d..5e0d076 100644 --- a/drivers/acpi/bus.c +++ b/drivers/acpi/bus.c @@ -37,9 +37,14 @@ #include #include #include +#include +#include #include "internal.h" +#undef pr_fmt +#define pr_fmt(fmt) "ACPI: " fmt + #define _COMPONENT ACPI_BUS_COMPONENT ACPI_MODULE_NAME("bus"); @@ -863,6 +868,62 @@ static int __init acpi_bus_init_irq(void) return 0; } +void __init acpi_load_initrd_ssdts(void) +{ + void *data = (void *)initrd_start; + int size = initrd_end - initrd_start; + const char *path = "kernel/firmware/acpi/overlay"; + long offset = 0; + struct cpio_data file; + struct acpi_table_header *header; + void *table; + acpi_status status; + + while (true) { + file = find_cpio_data(path, data, size, &offset); + if (!file.data) + break; + + data += offset; + size -= offset; + + if (file.size < sizeof(struct acpi_table_header)) { + pr_err("initrd table smaller than ACPI header [%s%s]\n", + path, file.name); + continue; + } + + header = file.data; + + if (file.size != header->length) { + pr_err("initrd file / table length mismatch [%s%s]\n", + path, file.name); + continue; + } + + if (memcmp(header->signature, ACPI_SIG_SSDT, 4)) { + pr_warn("skipping non-SSDT initrd table [%s%s]\n", + path, file.name); + continue; + } + + table = kmemdup(file.data, file.size, GFP_KERNEL); + if (!table) + continue; + + status = acpi_install_table((uintptr_t)table, 0); + if (ACPI_FAILURE(status)) { + pr_err("failed to install SSDT from initrd [%s%s]\n", + path, file.name); + kfree(table); + } + + pr_info("installed SSDT table found in initrd [%s%s][0x%x]\n", + path, file.name, header->length); + add_taint(TAINT_OVERLAY_ACPI_TABLE, LOCKDEP_STILL_OK); + } +} + /** * acpi_early_init - Initialize ACPICA and populate the ACPI namespace. * @@ -911,6 +972,8 @@ void __init acpi_early_init(void) goto error0; } + acpi_load_initrd_ssdts(); + status = acpi_load_tables(); if (ACPI_FAILURE(status)) { printk(KERN_ERR PREFIX -- 1.9.1