From patchwork Tue Feb 19 16:39:46 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Patchwork-Submitter: Wolfram Sang X-Patchwork-Id: 1044789 Return-Path: X-Original-To: incoming@patchwork.ozlabs.org Delivered-To: patchwork-incoming@bilbo.ozlabs.org Authentication-Results: ozlabs.org; spf=none (mailfrom) smtp.mailfrom=vger.kernel.org (client-ip=209.132.180.67; helo=vger.kernel.org; envelope-from=linux-i2c-owner@vger.kernel.org; receiver=) Authentication-Results: ozlabs.org; dmarc=none (p=none dis=none) header.from=sang-engineering.com Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by ozlabs.org (Postfix) with ESMTP id 443mg26Dxkz9s3l for ; Wed, 20 Feb 2019 03:39:58 +1100 (AEDT) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726565AbfBSQjy (ORCPT ); Tue, 19 Feb 2019 11:39:54 -0500 Received: from sauhun.de ([88.99.104.3]:47634 "EHLO pokefinder.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727082AbfBSQjy (ORCPT ); Tue, 19 Feb 2019 11:39:54 -0500 Received: from localhost (p54B338D8.dip0.t-ipconnect.de [84.179.56.216]) by pokefinder.org (Postfix) with ESMTPSA id DF95B3E48D4; Tue, 19 Feb 2019 17:39:52 +0100 (CET) From: Wolfram Sang To: linux-i2c@vger.kernel.org Cc: linux-renesas-soc@vger.kernel.org, Geert Uytterhoeven , Wolfram Sang Subject: [PATCH v2 2/2] i2c: gpio: fault-injector: add 'inject_panic' injector Date: Tue, 19 Feb 2019 17:39:46 +0100 Message-Id: <20190219163946.13559-3-wsa+renesas@sang-engineering.com> X-Mailer: git-send-email 2.11.0 In-Reply-To: <20190219163946.13559-1-wsa+renesas@sang-engineering.com> References: <20190219163946.13559-1-wsa+renesas@sang-engineering.com> MIME-Version: 1.0 Sender: linux-i2c-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-i2c@vger.kernel.org Add a fault injector simulating a Kernel panic happening after starting a transfer. Read the docs for its usage. Signed-off-by: Wolfram Sang --- Documentation/i2c/gpio-fault-injection | 26 ++++++++++++++++++++++++++ drivers/i2c/busses/i2c-gpio.c | 31 ++++++++++++++++++++++++++++++- 2 files changed, 56 insertions(+), 1 deletion(-) diff --git a/Documentation/i2c/gpio-fault-injection b/Documentation/i2c/gpio-fault-injection index 1f1bb96a64bd..c87f416d53dd 100644 --- a/Documentation/i2c/gpio-fault-injection +++ b/Documentation/i2c/gpio-fault-injection @@ -108,3 +108,29 @@ idle bus is: # echo 200 > lose_arbitration & # i2cget -y 0x3f + +Panic during transfer +===================== + +This fault injector will create a Kernel panic once the master under test +started a transfer. This usually means that the state machine of the bus master +driver will be ungracefully interrupted and the bus may end up in an unusual +state. Use this to check if your shutdown/reboot/boot code can handle this +scenario. + +"inject_panic" +-------------- + +This file is write only and you need to write the delay between the detected +start of a transmission and the induced Kernel panic (in µs, maximum is 100ms). +The calling process will then sleep and wait for the next bus clock. The +process is interruptible, though. + +Start of a transfer is detected by waiting for SCL going down by the master +under test. A good starting point for using this fault injector is: + +# echo 0 > inject_panic & +# i2cget -y + +Note that there doesn't need to be a device listening to the address you are +using. Results may vary depending on that, though. diff --git a/drivers/i2c/busses/i2c-gpio.c b/drivers/i2c/busses/i2c-gpio.c index 76e43783f50f..bba5c4627de3 100644 --- a/drivers/i2c/busses/i2c-gpio.c +++ b/drivers/i2c/busses/i2c-gpio.c @@ -231,6 +231,32 @@ static int fops_lose_arbitration_set(void *data, u64 duration) } DEFINE_DEBUGFS_ATTRIBUTE(fops_lose_arbitration, NULL, fops_lose_arbitration_set, "%llu\n"); +static irqreturn_t inject_panic_irq(int irq, void *dev_id) +{ + struct i2c_gpio_private_data *priv = dev_id; + + udelay(priv->scl_irq_data); + panic("I2C fault injector induced panic"); + + return IRQ_HANDLED; +} + +static int fops_inject_panic_set(void *data, u64 duration) +{ + struct i2c_gpio_private_data *priv = data; + + if (duration > 100 * 1000) + return -EINVAL; + + priv->scl_irq_data = duration; + /* + * Interrupt on falling SCL. This ensures that the master under test has + * really started the transfer. + */ + return i2c_gpio_fi_act_on_scl_irq(priv, inject_panic_irq); +} +DEFINE_DEBUGFS_ATTRIBUTE(fops_inject_panic, NULL, fops_inject_panic_set, "%llu\n"); + static void i2c_gpio_fault_injector_init(struct platform_device *pdev) { struct i2c_gpio_private_data *priv = platform_get_drvdata(pdev); @@ -256,9 +282,12 @@ static void i2c_gpio_fault_injector_init(struct platform_device *pdev) priv, &fops_incomplete_addr_phase); debugfs_create_file_unsafe("incomplete_write_byte", 0200, priv->debug_dir, priv, &fops_incomplete_write_byte); - if (priv->bit_data.getscl) + if (priv->bit_data.getscl) { + debugfs_create_file_unsafe("inject_panic", 0200, priv->debug_dir, + priv, &fops_inject_panic); debugfs_create_file_unsafe("lose_arbitration", 0200, priv->debug_dir, priv, &fops_lose_arbitration); + } debugfs_create_file_unsafe("scl", 0600, priv->debug_dir, priv, &fops_scl); debugfs_create_file_unsafe("sda", 0600, priv->debug_dir, priv, &fops_sda); }