From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-oi1-f181.google.com (mail-oi1-f181.google.com [209.85.167.181]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id C80F3328B54 for ; Fri, 7 Nov 2025 20:53:47 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.167.181 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1762548829; cv=none; b=iDfg5h9WBMr5B59AOsnFufryBhPgj3IyGaLoE1aDOTSRlYhSVpGcWgSFcI1Iq4TCauyZiAPm+LjoTXJlDpVTDY7LNSdnVDA4kgh/eOSbMUr+mTvENh9Mt81MPbhIbpPlBJcduQTwsZVvENvbry+A3Plh5yJQWdg1VHlpiVVCeZ4= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1762548829; c=relaxed/simple; bh=uBZhRBQvKxN5Rbc+PdSnTkkrZAa+WeV1PheO2s8Yfj0=; h=From:Date:Subject:MIME-Version:Content-Type:Message-Id:References: In-Reply-To:To:Cc; b=QkbLPlrXHx9kQbjOsPWoAFIp1YmeGtrG8cA3cUWLx1IuJnk+zsXfRS8sqxtUSnzyeod9uYPcUZmN+DW1vkY4imvJ6KT3xTYPJP1vKQxxEfHQR22S/1d8uuqP3FC9Gt3tKZdX/zOF9v6uXrce2IEtu6Mckbqkrq4HHihQTxfoA0c= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=baylibre.com; spf=pass smtp.mailfrom=baylibre.com; dkim=pass (2048-bit key) header.d=baylibre-com.20230601.gappssmtp.com header.i=@baylibre-com.20230601.gappssmtp.com header.b=vWJgL5pK; arc=none smtp.client-ip=209.85.167.181 Authentication-Results: smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=baylibre.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=baylibre.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=baylibre-com.20230601.gappssmtp.com header.i=@baylibre-com.20230601.gappssmtp.com header.b="vWJgL5pK" Received: by mail-oi1-f181.google.com with SMTP id 5614622812f47-44da774cc9dso572795b6e.3 for ; Fri, 07 Nov 2025 12:53:47 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=baylibre-com.20230601.gappssmtp.com; s=20230601; t=1762548827; x=1763153627; darn=vger.kernel.org; h=cc:to:in-reply-to:references:message-id:content-transfer-encoding :mime-version:subject:date:from:from:to:cc:subject:date:message-id :reply-to; bh=/rvhBJ+T6XZ73EAxGhr0kOh+HMxO6YR7XKNjge0UoKs=; b=vWJgL5pKyHRHWD+m8sSU71U/WljRfVTYhpRmQ5qnjd+XbaUHQCt7uYSA+ZCnOGeeEA 48lfAWda6LIJ49NVlgyylqqlIYZeDAIIr4NHwp+ysEAA5zY8w8HTqhSJZ7x33DxLqct5 n/roD+ztLL/Kke2JhKHoAs+SMZW6prsnJGC8oXFjnlt2OUonBVbtbAPp/0nFgOCHut5z 8TZfkm8/19vtICNbFDJcw7MHT9XgIl0aIZZiZTKxx55o4VEETge2NyCpy+LQuUrtuyKk IDSvqjB70ni79Pf0Kq4kO8gO1a0ZLFeREDb7dEtOx6DzieWwDk716dAmHI29OYw5Uirh Cq2w== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1762548827; x=1763153627; h=cc:to:in-reply-to:references:message-id:content-transfer-encoding :mime-version:subject:date:from:x-gm-gg:x-gm-message-state:from:to :cc:subject:date:message-id:reply-to; bh=/rvhBJ+T6XZ73EAxGhr0kOh+HMxO6YR7XKNjge0UoKs=; b=cChWkYogahuX4I78vd7bM7ppIZVy9IEcYY1UCawJTqhGqRUZTVecgismCMRGkb5SvJ 5Yy8UcvhuFlou0mt/BnURGcQiy6/8j5dy8ask+tKfpP2mK2X0wU03CH2oQmnja4A3xCx HzHTw3bQr4qnJhvk2ReuFGclsRm5tSLrKOzeEsRo8OgcVC4xHgp01kTKx/SVrRpO6FRn q7o9VSmPHLwXM4z7Mzfez2AO7Sm6/bhfOHX4trDvpHWJuuxkSA96VAlI7vf/5rFzalQg NbIy/8ygAQWjEsMsTTFoCAB4K0LKlOsb2sIeFOxgm5ZU1B/ltwpcQyNlyrnII+C7YoES o9ew== X-Forwarded-Encrypted: i=1; AJvYcCVHuy1hqOEMB/jEeN6aQULsiAfbNWd/9a6iWUBqGr1X5jZ675/1+CmMTUJBgoLcKeSTfFlnoJNm/Ls=@vger.kernel.org X-Gm-Message-State: AOJu0YzyW7thExMm6UysXbPBLwEo7B8qn7CjEpgOQ0U+/vBSZykD4GKU MB1slpletrQ984K1wTB4D5XGqDhy88vLYVgafHuxnPTCV26+Rk9SlDZ7QNiPX93xOJ4= X-Gm-Gg: ASbGncvL3yH2vGJyXRv4ik5Zlo8nR6LqURVePKK/eYmRVJvy7a2mcTHOFilK4BqynH3 E43/SVRUTE/31DKQbVpPhryuI2ntRmC+Yw7TFkvzpBMpPimk4VNOzOFSmy6hGKEKh26M0eSiGSR 2hSILBRJy/dh/pvETh9Bq05UtRjo/auYGOms7YpmKCFM8IG8brUUOZIKhH/mS2B4Z8ND8IWdxh7 gaI5GTwmXiPH6LZ7jxh4j2jdO82/9YPlQA3aGIMIFvwNPlEGSbbzmsh76F1mVxmdl/wT++K2QGg QZFrm8hWECWVlUTtAlcjRbf10yZboG1LSMkZ1DvajRfLUyWl65bbJZdmQMlkcEJcsiHj8lWR9kE 1Ho9y8B9HuxhQ40uVmJmpEwXY3isnOPhBr08UuZflzDaWxoJN+yiKVp9oNtNvBlPk+qoZGovvBh /7anPtI9W3kJetAn0= X-Google-Smtp-Source: AGHT+IEHuss/Yrh1cFcIOW73t6Nlukd7ORXBjsm4AOvCFUlFSow7BBb0+QgzjM0tTWDidJyPyKavcw== X-Received: by 2002:a05:6808:1523:b0:43f:63cc:aefa with SMTP id 5614622812f47-4502a4d4915mr342618b6e.48.1762548826608; Fri, 07 Nov 2025 12:53:46 -0800 (PST) Received: from [127.0.1.1] ([2600:8803:e7e4:500:7bb8:950b:327d:4ba4]) by smtp.gmail.com with ESMTPSA id 006d021491bc7-656c57eae5esm2915601eaf.16.2025.11.07.12.53.44 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 07 Nov 2025 12:53:46 -0800 (PST) From: David Lechner Date: Fri, 07 Nov 2025 14:52:49 -0600 Subject: [PATCH v2 3/6] spi: add multi_bus_mode field to struct spi_transfer Precedence: bulk X-Mailing-List: linux-iio@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 8bit Message-Id: <20251107-spi-add-multi-bus-support-v2-3-8a92693314d9@baylibre.com> References: <20251107-spi-add-multi-bus-support-v2-0-8a92693314d9@baylibre.com> In-Reply-To: <20251107-spi-add-multi-bus-support-v2-0-8a92693314d9@baylibre.com> To: Mark Brown , Rob Herring , Krzysztof Kozlowski , Conor Dooley , Marcelo Schmitt , Michael Hennerich , =?utf-8?q?Nuno_S=C3=A1?= , Jonathan Cameron , Andy Shevchenko Cc: Sean Anderson , linux-spi@vger.kernel.org, devicetree@vger.kernel.org, linux-kernel@vger.kernel.org, linux-iio@vger.kernel.org, David Lechner X-Mailer: b4 0.14.2 X-Developer-Signature: v=1; a=openpgp-sha256; l=3841; i=dlechner@baylibre.com; h=from:subject:message-id; bh=uBZhRBQvKxN5Rbc+PdSnTkkrZAa+WeV1PheO2s8Yfj0=; b=owEBbQGS/pANAwAKAcLMIAH/AY/AAcsmYgBpDlw6WL09bq9iy+/GN33p/vb2QS8/tlJSTsR8H F4YmjIugkKJATMEAAEKAB0WIQTsGNmeYg6D1pzYaJjCzCAB/wGPwAUCaQ5cOgAKCRDCzCAB/wGP wC8VB/4wshs9FzXaveEoEjEhM+PG0nDRH0fQV4ZScm5cEAV+PAJPkqnMUu+GvtyQo1Qe5OLjZcR rjJfhnozvGJ7I91mbnuVX6fXsJ8EbX+faFEJbSjEyLGtzsolg5Zhwbws8KKRDqEAC4Z4fIO8l/7 bwTVB4QbJqfYpYoAXGRS/HZ+KjFd3k5qBmC+B2G4h5Z4i1ux+qMF0otPmcksaPQMsHmZDRNFeWY TghgoBn+sobC+tXMSawtC4sKeBHToHRJwExDy/Y/0+araYcGqzQeynLrv/4d0NcEliRIS1CpP+T XDZxb1cv9dEKZok/p9EyooZrSDMqnK0atHgj4p5IUI+m8T48 X-Developer-Key: i=dlechner@baylibre.com; a=openpgp; fpr=8A73D82A6A1F509907F373881F8AF88C82F77C03 Add a new multi_bus_mode field to struct spi_transfer to allow peripherals that support multiple SPI buses to be used with a single SPI controller. This requires both the peripheral and the controller to have multiple serializers connected to separate data buses. It could also be used with a single controller and multiple peripherals that are functioning as a single logical device (similar to parallel memories). The possible values for this field have the following semantics: - SPI_MULTI_BUS_MODE_SINGLE: Only use the first bus. This means that it it is operating just like a conventional SPI bus. It is the default value so that existing drivers do not need to be modified. Example: tx_buf[0] = 0x88; struct spi_transfer xfer = { .tx_buf = tx_buf, .len = 1, }; spi_sync_transfer(spi, &xfer, 1); controller > data bits > peripheral ---------- ---------------- ---------- SDO 0 0-0-0-1-0-0-0-1 SDI 0 - SPI_MULTI_BUS_MODE_MIRROR: Send a single data word over all of the buses at the same time. This only makes sense for writes and not for reads. Example: tx_buf[0] = 0x88; struct spi_transfer xfer = { .tx_buf = tx_buf, .len = 1, .multi_bus_mode = SPI_MULTI_BUS_MODE_MIRROR, }; spi_sync_transfer(spi, &xfer, 1); controller > data bits > peripheral ---------- ---------------- ---------- SDO 0 0-0-0-1-0-0-0-1 SDI 0 SDO 1 0-0-0-1-0-0-0-1 SDI 1 - SPI_MULTI_BUS_MODE_STRIPE: Send or receive two different data words at the same time, one on each bus. Example: struct spi_transfer xfer = { .rx_buf = rx_buf, .len = 2, /* must be multiple of number of buses */ .multi_bus_mode = SPI_MULTI_BUS_MODE_STRIPE, }; spi_sync_transfer(spi, &xfer, 1); controller < data bits < peripheral ---------- ---------------- ---------- SDI 0 0-0-0-1-0-0-0-1 SDO 0 SDI 1 1-0-0-0-1-0-0-0 SDO 1 After the transfer, rx_buf[0] == 0x11 (word from SDO 0) and rx_buf[1] == 0x88 (word from SDO 1). If the transfer was longer, the data would continue in an alternating fashion. Acked-by: Nuno Sá Acked-by: Marcelo Schmitt Signed-off-by: David Lechner --- include/linux/spi/spi.h | 6 ++++++ 1 file changed, 6 insertions(+) diff --git a/include/linux/spi/spi.h b/include/linux/spi/spi.h index c314194d4e7e2b396795ece10e142118ca05f4eb..7d22ef5077d1229cac2574831f80092c591b972f 100644 --- a/include/linux/spi/spi.h +++ b/include/linux/spi/spi.h @@ -976,6 +976,8 @@ struct spi_res { * (SPI_NBITS_SINGLE) is used. * @rx_nbits: number of bits used for reading. If 0 the default * (SPI_NBITS_SINGLE) is used. + * @multi_bus_mode: How to serialize data on multiple buses. One of the + * SPI_MULTI_BUS_MODE_* values. * @len: size of rx and tx buffers (in bytes) * @speed_hz: Select a speed other than the device default for this * transfer. If 0 the default (from @spi_device) is used. @@ -1112,6 +1114,10 @@ struct spi_transfer { unsigned cs_change:1; unsigned tx_nbits:4; unsigned rx_nbits:4; + unsigned multi_bus_mode: 2; +#define SPI_MULTI_BUS_MODE_SINGLE 0 /* only use single bus */ +#define SPI_MULTI_BUS_MODE_STRIPE 1 /* one data word per bus */ +#define SPI_MULTI_BUS_MODE_MIRROR 2 /* same word sent on all buses */ unsigned timestamped:1; bool dtr_mode; #define SPI_NBITS_SINGLE 0x01 /* 1-bit transfer */ -- 2.43.0