From patchwork Thu Jan 28 02:57:30 2016 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: "Gabriel L. Somlo" X-Patchwork-Id: 574509 Return-Path: X-Original-To: incoming@patchwork.ozlabs.org Delivered-To: patchwork-incoming@bilbo.ozlabs.org Received: from lists.gnu.org (lists.gnu.org [IPv6:2001:4830:134:3::11]) (using TLSv1 with cipher AES256-SHA (256/256 bits)) (No client certificate requested) by ozlabs.org (Postfix) with ESMTPS id 68FD9140779 for ; Thu, 28 Jan 2016 13:59:53 +1100 (AEDT) Received: from localhost ([::1]:53594 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1aOcoJ-0007cb-Jw for incoming@patchwork.ozlabs.org; Wed, 27 Jan 2016 21:59:51 -0500 Received: from eggs.gnu.org ([2001:4830:134:3::10]:52689) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1aOcmq-0005BK-7O for qemu-devel@nongnu.org; Wed, 27 Jan 2016 21:58:21 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1aOcmp-0003ai-6f for qemu-devel@nongnu.org; Wed, 27 Jan 2016 21:58:20 -0500 Received: from relay-06.andrew.cmu.edu ([128.2.157.21]:35157 helo=relay.andrew.cmu.edu) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1aOcmp-0003ac-12 for qemu-devel@nongnu.org; Wed, 27 Jan 2016 21:58:19 -0500 Received: from HEDWIG.ini.cmu.edu (HEDWIG.INI.CMU.EDU [128.2.16.51]) by relay.andrew.cmu.edu (8.14.8/8.14.8) with ESMTP id u0S2vUma001004; Wed, 27 Jan 2016 21:57:32 -0500 From: "Gabriel L. Somlo" To: gregkh@linuxfoundation.org, robh+dt@kernel.org, pawel.moll@arm.com, mark.rutland@arm.com, ijc+devicetree@hellion.org.uk, galak@codeaurora.org, arnd@arndb.de, lersek@redhat.com, ralf@linux-mips.org, rmk+kernel@arm.linux.org.uk, eric@anholt.net, hanjun.guo@linaro.org, zajec5@gmail.com, sudeep.holla@arm.com, agross@codeaurora.org, linux-api@vger.kernel.org, linux-kernel@vger.kernel.org, devicetree@vger.kernel.org Date: Wed, 27 Jan 2016 21:57:30 -0500 Message-Id: <1453949850-13076-5-git-send-email-somlo@cmu.edu> X-Mailer: git-send-email 2.4.3 In-Reply-To: <1453949850-13076-1-git-send-email-somlo@cmu.edu> References: <1453949850-13076-1-git-send-email-somlo@cmu.edu> X-Scanned-By: MIMEDefang 2.74 on 128.2.157.21 X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.4.x X-Received-From: 128.2.157.21 Cc: peter.maydell@linaro.org, ehabkost@redhat.com, ard.biesheuvel@linaro.org, matt@codeblueprint.co.uk, stefanha@gmail.com, mst@redhat.com, qemu-devel@nongnu.org, leif.lindholm@linaro.org, luto@amacapital.net, kraxel@redhat.com, pbonzini@redhat.com, imammedo@redhat.com, revol@free.fr, rth@twiddle.net Subject: [Qemu-devel] [PATCH v7 4/4] devicetree: update documentation for fw_cfg ARM bindings X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.14 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org Sender: qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org From: Gabriel Somlo Remove fw_cfg hardware interface details from Documentation/devicetree/bindings/arm/fw-cfg.txt, and replace them with a pointer to the authoritative documentation in the QEMU source tree. Signed-off-by: Gabriel Somlo Cc: Laszlo Ersek Acked-by: Rob Herring Reviewed-by: Laszlo Ersek --- Documentation/devicetree/bindings/arm/fw-cfg.txt | 38 ++---------------------- 1 file changed, 2 insertions(+), 36 deletions(-) diff --git a/Documentation/devicetree/bindings/arm/fw-cfg.txt b/Documentation/devicetree/bindings/arm/fw-cfg.txt index 953fb64..fd54e1d 100644 --- a/Documentation/devicetree/bindings/arm/fw-cfg.txt +++ b/Documentation/devicetree/bindings/arm/fw-cfg.txt @@ -11,43 +11,9 @@ QEMU exposes the control and data register to ARM guests as memory mapped registers; their location is communicated to the guest's UEFI firmware in the DTB that QEMU places at the bottom of the guest's DRAM. -The guest writes a selector value (a key) to the selector register, and then -can read the corresponding data (produced by QEMU) via the data register. If -the selected entry is writable, the guest can rewrite it through the data -register. +The authoritative guest-side hardware interface documentation to the fw_cfg +device can be found in "docs/specs/fw_cfg.txt" in the QEMU source tree. -The selector register takes keys in big endian byte order. - -The data register allows accesses with 8, 16, 32 and 64-bit width (only at -offset 0 of the register). Accesses larger than a byte are interpreted as -arrays, bundled together only for better performance. The bytes constituting -such a word, in increasing address order, correspond to the bytes that would -have been transferred by byte-wide accesses in chronological order. - -The interface allows guest firmware to download various parameters and blobs -that affect how the firmware works and what tables it installs for the guest -OS. For example, boot order of devices, ACPI tables, SMBIOS tables, kernel and -initrd images for direct kernel booting, virtual machine UUID, SMP information, -virtual NUMA topology, and so on. - -The authoritative registry of the valid selector values and their meanings is -the QEMU source code; the structure of the data blobs corresponding to the -individual key values is also defined in the QEMU source code. - -The presence of the registers can be verified by selecting the "signature" blob -with key 0x0000, and reading four bytes from the data register. The returned -signature is "QEMU". - -The outermost protocol (involving the write / read sequences of the control and -data registers) is expected to be versioned, and/or described by feature bits. -The interface revision / feature bitmap can be retrieved with key 0x0001. The -blob to be read from the data register has size 4, and it is to be interpreted -as a uint32_t value in little endian byte order. The current value -(corresponding to the above outer protocol) is zero. - -The guest kernel is not expected to use these registers (although it is -certainly allowed to); the device tree bindings are documented here because -this is where device tree bindings reside in general. Required properties: