From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755235AbcA1OYA (ORCPT ); Thu, 28 Jan 2016 09:24:00 -0500 Received: from RELAY-06.ANDREW.CMU.EDU ([128.2.157.21]:41216 "EHLO relay.andrew.cmu.edu" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751633AbcA1OX6 (ORCPT ); Thu, 28 Jan 2016 09:23:58 -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 Cc: qemu-devel@nongnu.org, mst@redhat.com, imammedo@redhat.com, peter.maydell@linaro.org, leif.lindholm@linaro.org, ard.biesheuvel@linaro.org, pbonzini@redhat.com, kraxel@redhat.com, ehabkost@redhat.com, luto@amacapital.net, stefanha@gmail.com, revol@free.fr, matt@codeblueprint.co.uk, rth@twiddle.net Subject: [PATCH v8 4/4] devicetree: update documentation for fw_cfg ARM bindings Date: Thu, 28 Jan 2016 09:23:14 -0500 Message-Id: <1453990994-17801-5-git-send-email-somlo@cmu.edu> X-Mailer: git-send-email 2.4.3 In-Reply-To: <1453990994-17801-1-git-send-email-somlo@cmu.edu> References: <1453990994-17801-1-git-send-email-somlo@cmu.edu> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.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: -- 2.4.3