From patchwork Thu Jul 2 13:18:09 2015 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Cyrille Pitchen X-Patchwork-Id: 6709281 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 [198.145.29.136]) by patchwork2.web.kernel.org (Postfix) with ESMTP id 33E27C05AC for ; Thu, 2 Jul 2015 13:21:30 +0000 (UTC) Received: from mail.kernel.org (localhost [127.0.0.1]) by mail.kernel.org (Postfix) with ESMTP id 2EEDC2065A for ; Thu, 2 Jul 2015 13:21:29 +0000 (UTC) Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.9]) (using TLSv1.2 with cipher AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id CB8922070D for ; Thu, 2 Jul 2015 13:21:26 +0000 (UTC) Received: from localhost ([127.0.0.1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.80.1 #2 (Red Hat Linux)) id 1ZAeNw-0004Qj-UQ; Thu, 02 Jul 2015 13:18:36 +0000 Received: from eusmtp01.atmel.com ([212.144.249.242]) by bombadil.infradead.org with esmtps (Exim 4.80.1 #2 (Red Hat Linux)) id 1ZAeNd-0004Cs-V0 for linux-arm-kernel@lists.infradead.org; Thu, 02 Jul 2015 13:18:18 +0000 Received: from tenerife.corp.atmel.com (10.161.101.13) by eusmtp01.atmel.com (10.161.101.30) with Microsoft SMTP Server id 14.3.235.1; Thu, 2 Jul 2015 15:18:12 +0200 From: Cyrille Pitchen To: , , , , , , , Subject: [PATCH v4 1/5] ARM: at91/dt: add a new DT property to support FIFOs on Atmel USARTs Date: Thu, 2 Jul 2015 15:18:09 +0200 Message-ID: <600fa97640902a0a222901db18305749f57984e5.1435842688.git.cyrille.pitchen@atmel.com> X-Mailer: git-send-email 1.8.2.2 In-Reply-To: References: MIME-Version: 1.0 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20150702_061818_380070_BF7BA147 X-CRM114-Status: UNSURE ( 9.46 ) X-CRM114-Notice: Please train this message. X-Spam-Score: -4.8 (----) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.20 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: mark.rutland@arm.com, devicetree@vger.kernel.org, pawel.moll@arm.com, ijc+devicetree@hellion.org.uk, linux-kernel@vger.kernel.org, robh+dt@kernel.org, galak@codeaurora.org, Cyrille Pitchen , linux-arm-kernel@lists.infradead.org Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+patchwork-linux-arm=patchwork.kernel.org@lists.infradead.org X-Spam-Status: No, score=-4.8 required=5.0 tests=BAYES_00, RCVD_IN_DNSWL_MED, RP_MATCHES_RCVD, 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 This patch adds a new DT property, "atmel,fifo-size", to enable and set the maximum number of data the RX and TX FIFOs can store on FIFO capable USARTs. Please be aware that the VERSION register can not be used to guess the size of FIFOs. Indeed, for a given hardware version, the USARTs can be integrated on Atmel SoCs with different FIFO sizes. Also the "atmel,fifo-size" property is optional as older USARTs don't embed FIFO at all. Besides, the FIFO size can not be read or guessed from other registers: When designing the FIFO feature, no dedicated registers were added to store this size. Unsed spaces in the I/O register range are limited and better reserved for future usages. Instead, the FIFO size of each peripheral is documented in the programmer datasheet. Finally, on a given SoC, there can be several instances of USART with different FIFO sizes. This explain why we'd rather use a dedicated DT property than use the "compatible" property. Signed-off-by: Cyrille Pitchen Acked-by: Alexandre Belloni Acked-by: Nicolas Ferre --- Documentation/devicetree/bindings/serial/atmel-usart.txt | 3 +++ 1 file changed, 3 insertions(+) diff --git a/Documentation/devicetree/bindings/serial/atmel-usart.txt b/Documentation/devicetree/bindings/serial/atmel-usart.txt index 90787aa2e648..e6e6142e33ac 100644 --- a/Documentation/devicetree/bindings/serial/atmel-usart.txt +++ b/Documentation/devicetree/bindings/serial/atmel-usart.txt @@ -22,6 +22,8 @@ Optional properties: memory peripheral interface and USART DMA channel ID, FIFO configuration. Refer to dma.txt and atmel-dma.txt for details. - dma-names: "rx" for RX channel, "tx" for TX channel. +- atmel,fifo-size: maximum number of data the RX and TX FIFOs can store for FIFO + capable USARTs. compatible description: - at91rm9200: legacy USART support @@ -57,4 +59,5 @@ Example: dmas = <&dma0 2 0x3>, <&dma0 2 0x204>; dma-names = "tx", "rx"; + atmel,fifo-size = <32>; };