From patchwork Tue Dec 17 00:16:37 2013 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: al.stone@linaro.org X-Patchwork-Id: 3357791 Return-Path: X-Original-To: patchwork-linux-arm@patchwork.kernel.org Delivered-To: patchwork-parsemail@patchwork2.web.kernel.org Received: from mail.kernel.org (mail.kernel.org [198.145.19.201]) by patchwork2.web.kernel.org (Postfix) with ESMTP id DB757C0D4A for ; Tue, 17 Dec 2013 00:18:50 +0000 (UTC) Received: from mail.kernel.org (localhost [127.0.0.1]) by mail.kernel.org (Postfix) with ESMTP id EB8282025B for ; Tue, 17 Dec 2013 00:18:49 +0000 (UTC) Received: from casper.infradead.org (casper.infradead.org [85.118.1.10]) (using TLSv1.2 with cipher DHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id E95B72024D for ; Tue, 17 Dec 2013 00:18:48 +0000 (UTC) Received: from merlin.infradead.org ([2001:4978:20e::2]) by casper.infradead.org with esmtps (Exim 4.80.1 #2 (Red Hat Linux)) id 1VsiME-0006b4-18; Tue, 17 Dec 2013 00:17:54 +0000 Received: from localhost ([::1] helo=merlin.infradead.org) by merlin.infradead.org with esmtp (Exim 4.80.1 #2 (Red Hat Linux)) id 1VsiM2-0002Re-Sj; Tue, 17 Dec 2013 00:17:42 +0000 Received: from mail-ie0-f176.google.com ([209.85.223.176]) by merlin.infradead.org with esmtps (Exim 4.80.1 #2 (Red Hat Linux)) id 1VsiLb-0002MU-3o for linux-arm-kernel@lists.infradead.org; Tue, 17 Dec 2013 00:17:17 +0000 Received: by mail-ie0-f176.google.com with SMTP id at1so7464551iec.21 for ; Mon, 16 Dec 2013 16:16:52 -0800 (PST) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20130820; h=x-gm-message-state:from:to:cc:subject:date:message-id:in-reply-to :references; bh=kyQ7A6e/Upa6NttzsmzXrDJaNmF68zDZTlVixfnmPOY=; b=Exz2aH8ucsh2bjWaCAdXN4jgY1wPof7id90Eo+VME44RFysZ1oGrf4aw3cXxxiiqKa maFWTNipZkaHVvCGrPg5VzCWWxJdFHxsIsjuWjbaaO1NZeZixnG8aytgjiipF8+x8B49 zmIf14lPaQ/pf4/SLQSiYu9HXXaFgcqeq8gxBk4ATL+v3uye/F0OCNCRL9TnYgkW5M1m IEf25kLRObUMScN0gKt8v1C5sOsexJ4jJz6bacBzPhxEeJI6T3c4G5v8ALj/9Kk9M8LH 3X2hyE7ul1adRN3ZmTIHfQFzNtGnJdTEucl5B7DjTMZmE8g1NR1RhjdNG26M4C9i9yO3 9dWQ== X-Gm-Message-State: ALoCoQnSqkgLG8XRd8wLx8DPFApCn0tTc9hjcRVQVyJbhOfV/JUNBKNbZJKmpNX4bt9Gi/aTFaXe X-Received: by 10.43.124.134 with SMTP id go6mr116143icc.84.1387239411933; Mon, 16 Dec 2013 16:16:51 -0800 (PST) Received: from fidelio.ahs3.com (74-93-232-46-Colorado.hfc.comcastbusiness.net. [74.93.232.46]) by mx.google.com with ESMTPSA id j3sm12877632igj.9.2013.12.16.16.16.50 for (version=TLSv1.2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Mon, 16 Dec 2013 16:16:51 -0800 (PST) From: al.stone@linaro.org To: linux-acpi@vger.kernel.org, linux-arm-kernel@lists.infradead.org Subject: [PATCH v4 1/5] ACPI: introduce CONFIG_ACPI_REDUCED_HARDWARE to enable this ACPI mode Date: Mon, 16 Dec 2013 17:16:37 -0700 Message-Id: <1387239401-13918-2-git-send-email-al.stone@linaro.org> X-Mailer: git-send-email 1.8.3.1 In-Reply-To: <1387239401-13918-1-git-send-email-al.stone@linaro.org> References: <1387239401-13918-1-git-send-email-al.stone@linaro.org> X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20131216_191715_264081_5023DACB X-CRM114-Status: GOOD ( 18.01 ) X-Spam-Score: -0.1 (/) Cc: Hanjun Guo , patches@linaro.org, Al Stone , linaro-kernel@lists.linaro.org, linaro-acpi@lists.linaro.org X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.15 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , MIME-Version: 1.0 Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+patchwork-linux-arm=patchwork.kernel.org@lists.infradead.org X-Spam-Status: No, score=-2.2 required=5.0 tests=BAYES_00, RCVD_IN_DNSWL_MED, RP_MATCHES_RCVD, SUSPICIOUS_RECIPS, UNPARSEABLE_RELAY autolearn=unavailable version=3.3.1 X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on mail.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP From: Al Stone Hardware reduced mode, despite the name, exists primarily to allow newer platforms to use a much simpler form of ACPI that does not require supporting the legacy of previous versions of the specification. This mode was first introduced in the ACPI 5.0 specification, but because it is so much simpler and reduces the size of the object code needed to support ACPI, it is likely to be used more often in the near future. To enable the hardware reduced mode of ACPI on some platforms (such as ARM), we need to modify the kernel code and set ACPI_REDUCED_HARDWARE to TRUE in the ACPICA source. For ARM/ARM64, hardware reduced ACPI should be the only mode used; legacy mode would require modifications to SoCs in order to provide several x86-specific hardware features (e.g., an NMI and SMI support). We set ACPI_REDUCED_HARDWARE to TRUE in the ACPICA source by introducing a kernel config item to enable/disable ACPI_REDUCED_HARDWARE. We can then change the kernel config instead of having to modify the kernel source directly to enable the reduced hardware mode of ACPI. Lv Zheng suggested that this configuration item does not belong in ACPICA, the upstream source for much of the ACPI internals, but rather to the Linux kernel itself. Hence, we introduce this flag so that we can make ACPI_REDUCED_HARDWARE configurable. For the details of the discussion, please refer to: http://www.spinics.net/lists/linux-acpi/msg46369.html Even though support for X86 in hardware reduced mode is possible, it is NOT enabled. Extensive effort has gone into the Linux kernel so that there is a single kernel image than can run on all x86 hardware; the kernel changes run-time behavior to adapt to the hardware being used. This is not currently possible with the existing ACPICA infrastructure but only presents a problem on achitectures supporting both hardware-reduced and legacy modes of ACPI -- i.e., on x86 only. The problem with the current ACPICA code base is that if one builds legacy ACPI (a proper superset of hardware-reduced), the kernel can run in hardware- reduced with the proper ACPI tables, but there is still ACPICA code that could be executed even though it is not allowed by the specification. If one builds a hardware-reduced only ACPI, the kernel cannot run with ACPI tables that are for legacy mode. To ensure compliance with ACPI, one must therefore build two separate kernels. Once this problem has been properly fixed, we can then enable x86 hardware-reduced mode and use a single kernel. Signed-off-by: Hanjun Guo Signed-off-by: Al Stone --- drivers/acpi/Kconfig | 8 ++++++++ include/acpi/platform/aclinux.h | 6 ++++++ 2 files changed, 14 insertions(+) diff --git a/drivers/acpi/Kconfig b/drivers/acpi/Kconfig index 5d92485..53f0f16 100644 --- a/drivers/acpi/Kconfig +++ b/drivers/acpi/Kconfig @@ -343,6 +343,14 @@ config ACPI_BGRT data from the firmware boot splash. It will appear under /sys/firmware/acpi/bgrt/ . +config ACPI_REDUCED_HARDWARE + bool "Hardware-reduced ACPI support" + depends on ARM || ARM64 + help + This config adds support for Hardware-reduced ACPI. When this option + is selected, will generate a specialized version of ACPICA that ONLY + supports the ACPI "reduced hardware". + source "drivers/acpi/apei/Kconfig" config ACPI_EXTLOG diff --git a/include/acpi/platform/aclinux.h b/include/acpi/platform/aclinux.h index 28f4f4d..a33f502 100644 --- a/include/acpi/platform/aclinux.h +++ b/include/acpi/platform/aclinux.h @@ -52,6 +52,12 @@ #ifdef __KERNEL__ +/* Compile for reduced hardware mode if requested for this kernel config */ + +#ifdef CONFIG_ACPI_REDUCED_HARDWARE +#define ACPI_REDUCED_HARDWARE 1 +#endif + #include #include #include