From patchwork Wed Jan 26 11:26:06 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Miquel Raynal X-Patchwork-Id: 537522 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 05557C5DF62 for ; Wed, 26 Jan 2022 11:26:19 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S240689AbiAZL0Q (ORCPT ); Wed, 26 Jan 2022 06:26:16 -0500 Received: from relay3-d.mail.gandi.net ([217.70.183.195]:40023 "EHLO relay3-d.mail.gandi.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233677AbiAZL0P (ORCPT ); Wed, 26 Jan 2022 06:26:15 -0500 Received: (Authenticated sender: miquel.raynal@bootlin.com) by mail.gandi.net (Postfix) with ESMTPSA id 8A6E46000E; Wed, 26 Jan 2022 11:26:12 +0000 (UTC) From: Miquel Raynal To: Richard Weinberger , Vignesh Raghavendra , Tudor Ambarus , Pratyush Yadav , Michael Walle , Cc: Rob Herring , , Michal Simek , Thomas Petazzoni , Mark Brown , , Miquel Raynal Subject: [PATCH v6 2/3] spi: dt-bindings: Describe stacked/parallel memories modes Date: Wed, 26 Jan 2022 12:26:06 +0100 Message-Id: <20220126112608.955728-3-miquel.raynal@bootlin.com> X-Mailer: git-send-email 2.27.0 In-Reply-To: <20220126112608.955728-1-miquel.raynal@bootlin.com> References: <20220126112608.955728-1-miquel.raynal@bootlin.com> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-spi@vger.kernel.org Describe two new memories modes: - A stacked mode when the bus is common but the address space extended with an additinals wires. - A parallel mode with parallel busses accessing parallel flashes where the data is spread. Signed-off-by: Miquel Raynal Acked-by: Pratyush Yadav Reviewed-by: Rob Herring --- .../bindings/spi/spi-peripheral-props.yaml | 25 +++++++++++++++++++ 1 file changed, 25 insertions(+) diff --git a/Documentation/devicetree/bindings/spi/spi-peripheral-props.yaml b/Documentation/devicetree/bindings/spi/spi-peripheral-props.yaml index 5dd209206e88..fedb7ae98ff6 100644 --- a/Documentation/devicetree/bindings/spi/spi-peripheral-props.yaml +++ b/Documentation/devicetree/bindings/spi/spi-peripheral-props.yaml @@ -82,6 +82,31 @@ properties: description: Delay, in microseconds, after a write transfer. + stacked-memories: + description: Several SPI memories can be wired in stacked mode. + This basically means that either a device features several chip + selects, or that different devices must be seen as a single + bigger chip. This basically doubles (or more) the total address + space with only a single additional wire, while still needing + to repeat the commands when crossing a chip boundary. The size of + each chip should be provided as members of the array. + $ref: /schemas/types.yaml#/definitions/uint64-array + minItems: 2 + maxItems: 4 + + parallel-memories: + description: Several SPI memories can be wired in parallel mode. + The devices are physically on a different buses but will always + act synchronously as each data word is spread across the + different memories (eg. even bits are stored in one memory, odd + bits in the other). This basically doubles the address space and + the throughput while greatly complexifying the wiring because as + many busses as devices must be wired. The size of each chip should + be provided as members of the array. + $ref: /schemas/types.yaml#/definitions/uint64-array + minItems: 2 + maxItems: 4 + # The controller specific properties go here. allOf: - $ref: cdns,qspi-nor-peripheral-props.yaml#