From patchwork Mon Oct 3 20:06:09 2016 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Patchwork-Submitter: =?utf-8?q?Noralf_Tr=C3=B8nnes?= X-Patchwork-Id: 9360911 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork.web.codeaurora.org (Postfix) with ESMTP id CAED0607D8 for ; Mon, 3 Oct 2016 20:09:02 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id B368A2890B for ; Mon, 3 Oct 2016 20:09:02 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id A7E5E28A7D; Mon, 3 Oct 2016 20:09:02 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-4.2 required=2.0 tests=BAYES_00, RCVD_IN_DNSWL_MED autolearn=ham version=3.3.1 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.wl.linuxfoundation.org (Postfix) with ESMTPS id 957F52890B for ; Mon, 3 Oct 2016 20:09:01 +0000 (UTC) Received: from localhost ([127.0.0.1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.85_2 #1 (Red Hat Linux)) id 1br9WH-0002Jc-I7; Mon, 03 Oct 2016 20:07:25 +0000 Received: from smtp.domeneshop.no ([2a01:5b40:0:3005::1]) by bombadil.infradead.org with esmtps (Exim 4.85_2 #1 (Red Hat Linux)) id 1br9W0-0001lW-3O; Mon, 03 Oct 2016 20:07:09 +0000 Received: from 211.81-166-168.customer.lyse.net ([81.166.168.211]:36309 helo=localhost.localdomain) by smtp.domeneshop.no with esmtpsa (TLS1.1:DHE_RSA_AES_256_CBC_SHA1:256) (Exim 4.80) (envelope-from ) id 1br9Va-0006Iz-TK; Mon, 03 Oct 2016 22:06:42 +0200 From: =?UTF-8?q?Noralf=20Tr=C3=B8nnes?= To: wsa@the-dreams.de, swarren@wwwdotorg.org, eric@anholt.net Subject: [PATCH v4 2/7] i2c: bcm2835: Protect against unexpected TXW/RXR interrupts Date: Mon, 3 Oct 2016 22:06:09 +0200 Message-Id: <1475525174-28604-3-git-send-email-noralf@tronnes.org> X-Mailer: git-send-email 2.8.2 In-Reply-To: <1475525174-28604-1-git-send-email-noralf@tronnes.org> References: <1475525174-28604-1-git-send-email-noralf@tronnes.org> MIME-Version: 1.0 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20161003_130708_455373_4CBACE44 X-CRM114-Status: GOOD ( 14.42 ) 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: linux-rpi-kernel@lists.infradead.org, =?UTF-8?q?Noralf=20Tr=C3=B8nnes?= , linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-i2c@vger.kernel.org Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+patchwork-linux-arm=patchwork.kernel.org@lists.infradead.org X-Virus-Scanned: ClamAV using ClamSMTP If an unexpected TXW or RXR interrupt occurs (msg_buf_remaining == 0), the driver has no way to fill/drain the FIFO to stop the interrupts. In this case the controller has to be disabled and the transfer completed to avoid hang. (CLKT | ERR) and DONE interrupts are completed in their own paths, and the controller is disabled in the transfer function after completion. Unite the code paths and do disabling inside the interrupt routine. Clear interrupt status bits in the united completion path instead of trying to do it on every interrupt which isn't necessary. Only CLKT, ERR and DONE can be cleared that way. Add the status value to the error value in case of TXW/RXR errors to distinguish them from the other S_LEN error. Signed-off-by: Noralf Trønnes Reviewed-by: Eric Anholt --- Changes since v3: - Add comment about I2C_C_CLEAR on error drivers/i2c/busses/i2c-bcm2835.c | 40 +++++++++++++++++++++++++++++++--------- 1 file changed, 31 insertions(+), 9 deletions(-) -- 2.8.2 diff --git a/drivers/i2c/busses/i2c-bcm2835.c b/drivers/i2c/busses/i2c-bcm2835.c index f283b71..d2ba1a4 100644 --- a/drivers/i2c/busses/i2c-bcm2835.c +++ b/drivers/i2c/busses/i2c-bcm2835.c @@ -50,8 +50,6 @@ #define BCM2835_I2C_S_CLKT BIT(9) #define BCM2835_I2C_S_LEN BIT(10) /* Fake bit for SW error reporting */ -#define BCM2835_I2C_BITMSK_S 0x03FF - #define BCM2835_I2C_CDIV_MIN 0x0002 #define BCM2835_I2C_CDIV_MAX 0xFFFE @@ -111,20 +109,26 @@ static void bcm2835_drain_rxfifo(struct bcm2835_i2c_dev *i2c_dev) } } +/* + * Note about I2C_C_CLEAR on error: + * The I2C_C_CLEAR on errors will take some time to resolve -- if you were in + * non-idle state and I2C_C_READ, it sets an abort_rx flag and runs through + * the state machine to send a NACK and a STOP. Since we're setting CLEAR + * without I2CEN, that NACK will be hanging around queued up for next time + * we start the engine. + */ + static irqreturn_t bcm2835_i2c_isr(int this_irq, void *data) { struct bcm2835_i2c_dev *i2c_dev = data; u32 val, err; val = bcm2835_i2c_readl(i2c_dev, BCM2835_I2C_S); - val &= BCM2835_I2C_BITMSK_S; - bcm2835_i2c_writel(i2c_dev, BCM2835_I2C_S, val); err = val & (BCM2835_I2C_S_CLKT | BCM2835_I2C_S_ERR); if (err) { i2c_dev->msg_err = err; - complete(&i2c_dev->completion); - return IRQ_HANDLED; + goto complete; } if (val & BCM2835_I2C_S_DONE) { @@ -137,21 +141,38 @@ static irqreturn_t bcm2835_i2c_isr(int this_irq, void *data) i2c_dev->msg_err = BCM2835_I2C_S_LEN; else i2c_dev->msg_err = 0; - complete(&i2c_dev->completion); - return IRQ_HANDLED; + goto complete; } if (val & BCM2835_I2C_S_TXW) { + if (!i2c_dev->msg_buf_remaining) { + i2c_dev->msg_err = val | BCM2835_I2C_S_LEN; + goto complete; + } + bcm2835_fill_txfifo(i2c_dev); return IRQ_HANDLED; } if (val & BCM2835_I2C_S_RXR) { + if (!i2c_dev->msg_buf_remaining) { + i2c_dev->msg_err = val | BCM2835_I2C_S_LEN; + goto complete; + } + bcm2835_drain_rxfifo(i2c_dev); return IRQ_HANDLED; } return IRQ_NONE; + +complete: + bcm2835_i2c_writel(i2c_dev, BCM2835_I2C_C, BCM2835_I2C_C_CLEAR); + bcm2835_i2c_writel(i2c_dev, BCM2835_I2C_S, BCM2835_I2C_S_CLKT | + BCM2835_I2C_S_ERR | BCM2835_I2C_S_DONE); + complete(&i2c_dev->completion); + + return IRQ_HANDLED; } static int bcm2835_i2c_xfer_msg(struct bcm2835_i2c_dev *i2c_dev, @@ -181,8 +202,9 @@ static int bcm2835_i2c_xfer_msg(struct bcm2835_i2c_dev *i2c_dev, time_left = wait_for_completion_timeout(&i2c_dev->completion, BCM2835_I2C_TIMEOUT); - bcm2835_i2c_writel(i2c_dev, BCM2835_I2C_C, BCM2835_I2C_C_CLEAR); if (!time_left) { + bcm2835_i2c_writel(i2c_dev, BCM2835_I2C_C, + BCM2835_I2C_C_CLEAR); dev_err(i2c_dev->dev, "i2c transfer timed out\n"); return -ETIMEDOUT; }