From patchwork Fri Dec 13 17:58:27 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: "Lad, Prabhakar" X-Patchwork-Id: 851140 Received: from mail-wm1-f43.google.com (mail-wm1-f43.google.com [209.85.128.43]) (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 809B01F03CE; Fri, 13 Dec 2024 17:58:45 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.128.43 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1734112727; cv=none; b=n33bQ6G1HmPVelyLz7bF9jLS6i87CKeIDCS1W9ufECvNI8Uv6TBC7Qh0gBfaedtpyqdH0KiRv8mNyGTolkbmsjxpsoBcfxcnM1vPP/dDm1PHhDv/nVqYy8s5tLEGhD+SNE67mFR+YMdDWPvYW9hCzH5mnJJzFcBRb8A7M+SqlvA= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1734112727; c=relaxed/simple; bh=DpIe8jgrItvnhSA7SbrN6HdkN/siT0OgekjPRdjzvzI=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=oA3hk2qjKpayh46P77P06dda080VJguHJgs4tA7KuKUtdEZn1OKDCCY4eXOBqFXEowcV1ah7XHDurC7CSrB+hgSzLkLj6SBoKyGxkNZ+Xhz9ylJBmVEKkgBu/KKR+oHF2on2J7aUtuKyZUZYQ3RMDZK0MTtESVYWfOXH3HFp7SE= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=gmail.com; spf=pass smtp.mailfrom=gmail.com; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b=hGMKp0Kd; arc=none smtp.client-ip=209.85.128.43 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=gmail.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=gmail.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="hGMKp0Kd" Received: by mail-wm1-f43.google.com with SMTP id 5b1f17b1804b1-43621d27adeso14612915e9.2; Fri, 13 Dec 2024 09:58:45 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20230601; t=1734112724; x=1734717524; darn=vger.kernel.org; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:from:to:cc:subject:date :message-id:reply-to; bh=fmWil1cxIYx3s+bMSXeGjJtO1HSZn1VjUtrO9+QRfPU=; b=hGMKp0Kd/vf57E+jM/Flc/rye4lO6qHvjCL2aK7S4KbHQeKPNATWm3+CiOLuV9k4gq 3HY0kLk4GGoGoq3xZ8pJFlqxRnptt9qW6MKO5Xd5M1Gjm8H093VFxFwXlrcSmeuumdd6 ggUJHsbXwmeZ8WfDDhWnYq7gQvVtKSJyVqgTBz9Ak4LFRGerrhRyltj0oM2XyGZpr3W3 XLBmXeBAlG6Jz7cSJdk9Sl8+bUp++0TdsGxZiZ7LDSJ9Sr+gymI1vuDaWrhZFqs3GbqB w/DKRXaoABlWzlGyQv2BlON1jvs3tH62h40GCAdBn/haEPKlHfwxcL1BD9zgpQNYzh8/ qTuA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1734112724; x=1734717524; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:x-gm-message-state:from:to:cc :subject:date:message-id:reply-to; bh=fmWil1cxIYx3s+bMSXeGjJtO1HSZn1VjUtrO9+QRfPU=; b=XGq6FOQf4mwwhIakIlc4bEqE0HD0krQkwFWSIarmRg74fph8dE0mwhwR4zjsdd1qDB oUglYHjLvnrQ/B/Qdfa3WS7kS9nPB/P2B5ktrjKCTEXWCo/OExsmY9l1taZXZiMUhbxD OPchS8HP5Xo9KZLvIA0QIbSFrEytJ4QRGu7iWD2hRhGG8Q3nTaQB1yG11fIscFJdtu3D 2SBWe1lBDzrSvYf9LzbvSlzY262eiVelK4fnhVtVZX2Bdl1OtP19aA+NWEs3vowxAygk e9CaZlBNiATgREDelKOhtHlt3pU18qu7/5uUKyr9EbGhqNJcKWbryMki7IgZeuKAo71Z WM6Q== X-Forwarded-Encrypted: i=1; AJvYcCUHcrQ9r4BoooiPnOTrpMBDZ3DVsYHdWtl4NGtdV1o/unvNfYOuYMhx/6eF+KyyyOp6RpAZXdZLef1dHtJ1@vger.kernel.org, AJvYcCUxGat/wKYalq9KBKAVTbuUL1Ap/OKL9mhlbOGGn7n5SM4efoRgcftCnOPIk/GjZtzZRfQOGWQjCHE=@vger.kernel.org X-Gm-Message-State: AOJu0Yza6ie80mpYWcxYRIHKZ4x2r4V4uJvxXpQkfV9sMtfbw06bkjOs Rn497LIrv4iYBYy/6rcdqVqqSUUuP3cBXqLnaO6fS6ARPniOgwBd X-Gm-Gg: ASbGncvH+jS12yQ+hXqLQ47ejdWmGnS3OoX9i+dyTNimR/o/oOnZBGjRNJKXEyTs5qk Iod82I0K11daexiNoOPP1KWGH+GDJWXBklXsTab/0+oS5Q/QoWGQJD7vTc43F2ZnEOaacC0ZmEY VJg0H4igOYcWvRqsPVzt6Hkozh40UJykcWm6A9stb/bBUGy46aHfkVW6GMVIDQvbAuEicpYf4u0 mqvcDl9+jg2mvGzukjawYFDtjzUbajPxlwC+PovtsaREaWiURDy3pF8Qh9woTdJPQdHKPT4xu7k x9tWCyPMTA== X-Google-Smtp-Source: AGHT+IEDHANdD0OtyAiI+EfqRMxcoPqhmLiqQ33TANc7Xqyva6QVsG50d/sXV3IKiC+zIFMXPK+inw== X-Received: by 2002:a05:600c:1c82:b0:435:9ed3:5688 with SMTP id 5b1f17b1804b1-4362aa6f39emr33644775e9.18.1734112723656; Fri, 13 Dec 2024 09:58:43 -0800 (PST) Received: from prasmi.Home ([2a06:5906:61b:2d00:4eec:e99c:89a6:d7a6]) by smtp.gmail.com with ESMTPSA id ffacd0b85a97d-388c804d573sm119088f8f.64.2024.12.13.09.58.42 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 13 Dec 2024 09:58:42 -0800 (PST) From: Prabhakar X-Google-Original-From: Prabhakar To: Chris Brandt , Andi Shyti , Philipp Zabel , Wolfram Sang , Geert Uytterhoeven Cc: linux-renesas-soc@vger.kernel.org, linux-i2c@vger.kernel.org, linux-kernel@vger.kernel.org, Prabhakar , Biju Das , Fabrizio Castro , Lad Prabhakar Subject: [PATCH 8/9] i2c: riic: Add `riic_bus_barrier()` to check bus availability Date: Fri, 13 Dec 2024 17:58:27 +0000 Message-ID: <20241213175828.909987-9-prabhakar.mahadev-lad.rj@bp.renesas.com> X-Mailer: git-send-email 2.43.0 In-Reply-To: <20241213175828.909987-1-prabhakar.mahadev-lad.rj@bp.renesas.com> References: <20241213175828.909987-1-prabhakar.mahadev-lad.rj@bp.renesas.com> Precedence: bulk X-Mailing-List: linux-i2c@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 From: Lad Prabhakar Introduce a new `riic_bus_barrier()` function to verify bus availability before initiating an I2C transfer. This function enhances the bus arbitration check by ensuring that the SDA and SCL lines are not held low, in addition to checking the BBSY flag using `readb_poll_timeout()`. Previously, only the BBSY flag was checked to determine bus availability. However, it is possible for the SDA line to remain low even when BBSY = 0. This new implementation performs an additional check on the SDA and SCL lines to avoid potential bus contention issues. Signed-off-by: Lad Prabhakar --- drivers/i2c/busses/i2c-riic.c | 29 ++++++++++++++++++++++++++--- 1 file changed, 26 insertions(+), 3 deletions(-) diff --git a/drivers/i2c/busses/i2c-riic.c b/drivers/i2c/busses/i2c-riic.c index 48812e7d9cef..919da1bdcce5 100644 --- a/drivers/i2c/busses/i2c-riic.c +++ b/drivers/i2c/busses/i2c-riic.c @@ -40,6 +40,7 @@ #include #include #include +#include #include #include #include @@ -50,6 +51,8 @@ #define ICCR1_ICE BIT(7) #define ICCR1_IICRST BIT(6) #define ICCR1_SOWP BIT(4) +#define ICCR1_SCLI BIT(1) +#define ICCR1_SDAI BIT(0) #define ICCR2_BBSY BIT(7) #define ICCR2_SP BIT(3) @@ -135,6 +138,27 @@ static inline void riic_clear_set_bit(struct riic_dev *riic, u8 clear, u8 set, u riic_writeb(riic, (riic_readb(riic, reg) & ~clear) | set, reg); } +static int riic_bus_barrier(struct riic_dev *riic) +{ + int ret; + u8 val; + + /* + * The SDA line can still be low even when BBSY = 0. Therefore, after checking + * the BBSY flag, also verify that the SDA and SCL lines are not being held low. + */ + ret = readb_poll_timeout(riic->base + riic->info->regs[RIIC_ICCR2], val, + !(val & ICCR2_BBSY), 10, riic->adapter.timeout); + if (ret) + return -EBUSY; + + if (!(riic_readb(riic, RIIC_ICCR1) & ICCR1_SDAI) || + !(riic_readb(riic, RIIC_ICCR1) & ICCR1_SCLI)) + return -EBUSY; + + return 0; +} + static int riic_xfer(struct i2c_adapter *adap, struct i2c_msg msgs[], int num) { struct riic_dev *riic = i2c_get_adapdata(adap); @@ -147,10 +171,9 @@ static int riic_xfer(struct i2c_adapter *adap, struct i2c_msg msgs[], int num) if (ret) return ret; - if (riic_readb(riic, RIIC_ICCR2) & ICCR2_BBSY) { - riic->err = -EBUSY; + riic->err = riic_bus_barrier(riic); + if (riic->err) goto out; - } reinit_completion(&riic->msg_done); riic->err = 0;