From patchwork Thu Jan 12 22:34:57 2017 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Chris Bostic X-Patchwork-Id: 9514349 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork.web.codeaurora.org (Postfix) with ESMTP id 64D0860476 for ; Thu, 12 Jan 2017 22:35:28 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 6B3ED2871C for ; Thu, 12 Jan 2017 22:35:28 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 5E3802871E; Thu, 12 Jan 2017 22:35:28 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-4.1 required=2.0 tests=BAYES_00, DKIM_ADSP_CUSTOM_MED, DKIM_SIGNED,FREEMAIL_FROM,RCVD_IN_DNSWL_MED,T_DKIM_INVALID autolearn=unavailable version=3.3.1 Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.9]) (using TLSv1.2 with cipher AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.wl.linuxfoundation.org (Postfix) with ESMTPS id E5BA72871C for ; Thu, 12 Jan 2017 22:35:27 +0000 (UTC) Received: from localhost ([127.0.0.1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.87 #1 (Red Hat Linux)) id 1cRnxu-0003Xn-FF; Thu, 12 Jan 2017 22:35:26 +0000 Received: from mail-ot0-x243.google.com ([2607:f8b0:4003:c0f::243]) by bombadil.infradead.org with esmtps (Exim 4.87 #1 (Red Hat Linux)) id 1cRnxq-0002Fr-6F for linux-arm-kernel@lists.infradead.org; Thu, 12 Jan 2017 22:35:24 +0000 Received: by mail-ot0-x243.google.com with SMTP id 73so489873otj.1 for ; Thu, 12 Jan 2017 14:35:01 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=from:to:cc:subject:date:message-id; bh=IfJP766k2tsoa8fJZy6vhiWDB6CYJY9aCF1PtY3PsSM=; b=W6CkAqpW5bYmQKuPWkcS6K/j6KZglCWh+cr7hWoTnDXIEki2ixxPc9bhwFq4Ey9zqF YJA9A6lBhvUXhyf5lhVsejHCbuFsL+bWWmFITrFXuv8YkHLFwYk/qwIycWj4eZuefq0U n6CayashoczyZh1euYE+kfgUw+vPmz7n0C1Vz8BuFVthhL4kuZ4fq8Hq6zz4slqLRo72 pP7KxQj/XUgiWb7PWvXNIOm4SM32o8XkQ54ZfFd5aBtxmEkyJWCUCNm6ubWtBrOUWAv0 4EAqeyu3OuEWxaB09+UiwYrF/D0OxIU82o9JBrEQnoYXCKdEW/HhsZ9e5YOVjlE2xbN6 0GHg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:cc:subject:date:message-id; bh=IfJP766k2tsoa8fJZy6vhiWDB6CYJY9aCF1PtY3PsSM=; b=jP/vpVrAbNY1v923ADcNOt87+TdwO/79TBUjOdGyPngngaVkfmQIqInvagNVhXntht Ub4Kvn7YAEFWoC07G5TGGGZ55SkoRopNsZIZAB1+Lc/tKXxQwKkCi+sMkdsbEJTftkr/ wZ71+G01/kAxR+cTUCOpgz5Yr4PD6TaCuJN4CwLO+Dw4VR3fm8pxzBXf4lxqMOHy6C14 N7r0I2TWyFGMBLJUJR6M9zyxa8uACCpnI91q9qN6wXcGJXYLC1m+53sWL8j1OxtMDBc+ sf/BTtpIHwgAchxfry9urz1K07q+Y0IUT7rMv1DIytRGPkOBiCPOLMbSOd+XPoWEgD+1 ewsQ== X-Gm-Message-State: AIkVDXJHmjqLOesQN4af4TjNzLUnbu/WCFEWw+sbcuDq+T9+nmLzKtjFriWpZAV3Bj616w== X-Received: by 10.157.29.100 with SMTP id m91mr7133803otm.6.1484260501145; Thu, 12 Jan 2017 14:35:01 -0800 (PST) Received: from Christophers-MacBook-Pro.local.com (45-20-192-79.lightspeed.austtx.sbcglobal.net. [45.20.192.79]) by smtp.gmail.com with ESMTPSA id h74sm5028928oic.9.2017.01.12.14.34.59 (version=TLS1 cipher=AES128-SHA bits=128/128); Thu, 12 Jan 2017 14:34:59 -0800 (PST) From: christopher.lee.bostic@gmail.com To: robh+dt@kernel.org, mark.rutland@arm.com, linux@armlinux.org.uk, gregkh@linuxfoundation.org, mturquette@baylibre.com, geert+renesas@glider.be, devicetree@vger.kernel.org, linux-arm-kernel@lists.infradead.org, joel@jms.id.au, jk@ozlabs.org, linux-kernel@vger.kernel.org, andrew@aj.id.au, alistair@popple.id.au, benh@kernel.crashing.org Subject: [PATCH v2 14/18] drivers/fsi: Add FSI bus documentation Date: Thu, 12 Jan 2017 16:34:57 -0600 Message-Id: <1484260497-80241-1-git-send-email-christopher.lee.bostic@gmail.com> X-Mailer: git-send-email 2.7.4 (Apple Git-66) X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20170112_143522_288243_A3CFD053 X-CRM114-Status: GOOD ( 16.00 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.21 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Chris Bostic MIME-Version: 1.0 Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+patchwork-linux-arm=patchwork.kernel.org@lists.infradead.org X-Virus-Scanned: ClamAV using ClamSMTP From: Chris Bostic Add details on the basic functions of the FSI serial bus. Signed-off-by: Chris Bostic --- Documentation/devicetree/bindings/fsi/fsi.txt | 54 +++++++++++++++++++++++++++ 1 file changed, 54 insertions(+) create mode 100644 Documentation/devicetree/bindings/fsi/fsi.txt diff --git a/Documentation/devicetree/bindings/fsi/fsi.txt b/Documentation/devicetree/bindings/fsi/fsi.txt new file mode 100644 index 0000000..7fa2394 --- /dev/null +++ b/Documentation/devicetree/bindings/fsi/fsi.txt @@ -0,0 +1,54 @@ +FSI: Flexible Support processor Interface + +FSI is a two line serial bus capable of running at speeds up to 166 MHz. +The lines consist of a clock responsible for synchronizing the target device +(slave) with the master which is responsible for all transactions on the bus. +The master owns the clock line and is the only side allowed to change its +state. The second line, SDA, is a data line that conveys information to/from +the slave who samples based on the clock line. The data line is +bi-directional. + +The master initiates communication by sending a command to the slave and +depending on the type of command will allow the slave to control the bus +to return requested data. All commands are CRC protected. The slave upon +receipt of a command will determine if the CRC is correct and discard +the data if noise has corrupted the line. In the same manner the master +will verify the CRC received from the slave. + +Types of commands: +Read 32 bit: Read a 32 bit word from a specified address on the slave. +Read 16 bit: Read a 16 bit 'half word' from a specified address on the slave. +read 8 bit: Read a byte from a specified address on the slave. +Write 32,16,8 bit: Write to a specified address on the slave with the provided + data. +BREAK: Initialize the slave's logic to receive commands. +TERM: Terminate the slave's error lockout to resume communications + after an error on the bus is detected. +D-POLL: Poll the slave to determine when it is no longer buy processing + a previous command. +I-POLL: Interrupt signal check. Master queries slave to see if any + interrupts are asserting. + +High fanout capability: +FSI buses can be chained together in 'hub' configurations to expand the +available communications channels and thus allow connetion to more slaves. + + +Typical implementation + + FSI master ----- slave with local FSI master (hub) ------- downstream slave + + +Each two line combination of a clock and data line is collectively referred +to as a 'FSI link'. Depending on hardware the primary FSI master may support +up to 64 links. Hub FSI masters can support at most 8 links. Total number +of supported slaves can grow exponentially depending on how many hubs are +placed in the path. Presently only two hubs in the chain are allowed but +in the future this may be expanded. + +The slave hardware logic responsible for decoding FSI master commands is +contained in a CFAM (Common Field replaceable unit Access Macro). Up to +4 slaves or CFAMs can be connected on each FSI link. CFAMs in addition +to the slave logic (or engine) can contain other functions that allow access +via FSI. Common additional functionality includes I2C masters, GPIO +controllers, UARTs, etc...