From patchwork Wed Oct 31 16:52:13 2012 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Pantelis Antoniou X-Patchwork-Id: 1697761 Return-Path: X-Original-To: patchwork-linux-arm@patchwork.kernel.org Delivered-To: patchwork-process-083081@patchwork2.kernel.org Received: from merlin.infradead.org (merlin.infradead.org [205.233.59.134]) by patchwork2.kernel.org (Postfix) with ESMTP id 7FFC0DF2AB for ; Mon, 5 Nov 2012 14:02:36 +0000 (UTC) Received: from localhost ([::1] helo=merlin.infradead.org) by merlin.infradead.org with esmtp (Exim 4.76 #1 (Red Hat Linux)) id 1TVNCn-0004hv-Uz; Mon, 05 Nov 2012 13:59:11 +0000 Received: from li42-95.members.linode.com ([209.123.162.95]) by merlin.infradead.org with esmtps (Exim 4.76 #1 (Red Hat Linux)) id 1TTH26-0002sr-7G for linux-arm-kernel@lists.infradead.org; Tue, 30 Oct 2012 18:59:30 +0000 Received: from sles11esa.localdomain (unknown [195.97.110.117]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (No client certificate requested) (Authenticated sender: panto) by li42-95.members.linode.com (Postfix) with ESMTPSA id DB4EE9C1EA; Tue, 30 Oct 2012 18:59:23 +0000 (UTC) From: Pantelis Antoniou To: Tony Lindgren Subject: [RFC 7/7] capebus: Documentation; capebus-summary Date: Wed, 31 Oct 2012 18:52:13 +0200 Message-Id: <1351702333-8456-8-git-send-email-panto@antoniou-consulting.com> X-Mailer: git-send-email 1.7.12 In-Reply-To: <1351702333-8456-1-git-send-email-panto@antoniou-consulting.com> References: <1351702333-8456-1-git-send-email-panto@antoniou-consulting.com> X-Bad-Reply: References and In-Reply-To but no 'Re:' in Subject. X-Spam-Note: CRM114 invocation failed X-Spam-Score: 1.3 (+) X-Spam-Report: SpamAssassin version 3.3.2 on merlin.infradead.org summary: Content analysis details: (1.3 points) pts rule name description ---- ---------------------- -------------------------------------------------- 3.2 DATE_IN_FUTURE_12_24 Date: is 12 to 24 hours after Received: date -1.9 BAYES_00 BODY: Bayes spam probability is 0 to 1% [score: 0.0000] X-Mailman-Approved-At: Mon, 05 Nov 2012 08:45:41 -0500 Cc: Matt Porter , devicetree-discuss@lists.ozlabs.org, Pantelis Antoniou , linux-kernel@vger.kernel.org, Russ Dill , linux-omap@vger.kernel.org, Koen Kooi , linux-arm-kernel@lists.infradead.org X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.14 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , MIME-Version: 1.0 Sender: linux-arm-kernel-bounces@lists.infradead.org Errors-To: linux-arm-kernel-bounces+patchwork-linux-arm=patchwork.kernel.org@lists.infradead.org Small summary of capebus. Signed-off-by: Pantelis Antoniou --- Documentation/capebus/capebus-summary | 40 +++++++++++++++++++++++++++++++++++ 1 file changed, 40 insertions(+) create mode 100644 Documentation/capebus/capebus-summary diff --git a/Documentation/capebus/capebus-summary b/Documentation/capebus/capebus-summary new file mode 100644 index 0000000..742e33c --- /dev/null +++ b/Documentation/capebus/capebus-summary @@ -0,0 +1,40 @@ +Overview of Linux kernel Capebus support +======================================== + +30-Oct-2012 + +What is Capebus? +---------------- +Capebus is an abstract concept. There's no such thing as a vanilla physical +capebus, what is there is a concept and a method on how various capebus +based implementations can be made. + +Capebus is created to address the problem of many SoCs that can provide a +multitude of hardware interfaces but in order to keep costs down the main +boards only support a limited number of them. The rest are typically brought +out to pin connectors on to which other boards, named capes are connected and +allow those peripherals to be used. + +These capes connect to the SoC interfaces but might also contain various other +parts that may need some kind of driver to work. + +Since SoCs have limited pins and pin muxing options, not all capes can work +together so some kind of resource tracking (at least for the pins in use) is +required. + +Before capebus all of this took place in the board support file, and frankly +for boards with too many capes it was becoming unmanageable. + +Capebus provides a virtual bus, which along with a board specific controller, +cape drivers can be written using the standard Linux device model. + +What kind of systems/boards capebus supports? +--------------------------------------------- + +The core capebus infrastructure is not depended on any specific board. +However capebus needs a board controller to provide services to the cape devices +it controls. Services like addressing and resource reservation are provided +by the board controller. + +Capebus at the moment only support TI's Beaglebone platform. +