From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-15.3 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,NICE_REPLY_A,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED, USER_AGENT_SANE_1 autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 9A94FC07E9C for ; Wed, 14 Jul 2021 11:31:25 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 74FF76128C for ; Wed, 14 Jul 2021 11:31:25 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S239222AbhGNLeP (ORCPT ); Wed, 14 Jul 2021 07:34:15 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:48750 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S239189AbhGNLeO (ORCPT ); Wed, 14 Jul 2021 07:34:14 -0400 Received: from mail-oi1-x22d.google.com (mail-oi1-x22d.google.com [IPv6:2607:f8b0:4864:20::22d]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 023DEC06175F; Wed, 14 Jul 2021 04:31:23 -0700 (PDT) Received: by mail-oi1-x22d.google.com with SMTP id w127so1852215oig.12; Wed, 14 Jul 2021 04:31:22 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=sender:to:cc:references:from:subject:message-id:date:user-agent :mime-version:in-reply-to:content-language:content-transfer-encoding; bh=xnH81NFaI02nLQu6OEHeAUXcDBEPoMvbyC7khHizRgQ=; b=PnlX0M4aC/RoQaeiGp8bjP9KLJ97B7KDaOy4MDStGDvNJjp7OuX9w3y7WHYEHLe66/ 2WhNTZc+WlQqhTuJd1MsPgi2vvqBhR2azMDINlafNfS3N+2F679AFfXT/lJWuCs3bC6E YKqonF/rEbVDZ5uHo+GyQUM9NygOSJ1nmSOzTFanoWAaAOYXpwBJCmOulb0Snm0QHlEi A9QUVNHZ9lgY2Mn+4zLEic98r+6m74KDckc7skmGy+V9RncWOsPfUbFcJkO+tmsYm/KV bHLgU/VN/ka5VpCoiUTzx+aQTxt6ywMiA9lq+8m7nQc4Il2UKOlil35CHrkBas5ugFT0 pz5w== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:sender:to:cc:references:from:subject:message-id :date:user-agent:mime-version:in-reply-to:content-language :content-transfer-encoding; bh=xnH81NFaI02nLQu6OEHeAUXcDBEPoMvbyC7khHizRgQ=; b=SsfVnIhdroAZwkRJiw1hmbBc6c8Stn7b5VHzRz4jCHCiVQiBxKBHKD06QhfGRSgkBR Ed3+YSD7sb5g27nItnOC+kmt9+zQ3HIpM53v9wVeQmllTOueIeVfJXj5wJFmLMP2jZwx 8/eCGFCeWtxO9gBEYeqlNN4YlzSzozl2R/W58SCOXITQMP/AjMlMFwLRyq91+nQ/e/7/ q/wGBwtOMclFqahBVfc7Wmw+tfLTmT6tOIttCmAWYrN4wCK8BvXqyZlcWd+6WqcEIllO Vem00oUDgY6GV86KzXSIbHkyKi5kE2LxGPN9EoVcdx8KWwu88nCruxOtGzmiTUA9p3vq p3yQ== X-Gm-Message-State: AOAM531LUHEVCftjHDHsS91uiH5Oa3Mgs/+vDjkV8j8edho4CLnqTGFS R80DausirL8UNvlkn6qN08Y= X-Google-Smtp-Source: ABdhPJxR7GohrOlCne1ai7QFbrdTQZfG7CvJYyMegJRnMlqIJeuPzmcyg9RLISIeRVIFdWeEjkbozQ== X-Received: by 2002:a05:6808:d2:: with SMTP id t18mr2398300oic.45.1626262281977; Wed, 14 Jul 2021 04:31:21 -0700 (PDT) Received: from server.roeck-us.net ([2600:1700:e321:62f0:329c:23ff:fee3:9d7c]) by smtp.gmail.com with ESMTPSA id v42sm420771ott.70.2021.07.14.04.31.19 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Wed, 14 Jul 2021 04:31:21 -0700 (PDT) Sender: Guenter Roeck To: Srinivas Neeli , Shubhrajyoti Datta , Srinivas Goud , Michal Simek Cc: "wim@linux-watchdog.org" , "linux-watchdog@vger.kernel.org" , "linux-kernel@vger.kernel.org" , git References: <20210527095709.12841-1-srinivas.neeli@xilinx.com> <20210527095709.12841-3-srinivas.neeli@xilinx.com> From: Guenter Roeck Subject: Re: [PATCH 2/3] watchdog: xilinx_wwdt: Add Versal Window watchdog mode Message-ID: Date: Wed, 14 Jul 2021 04:31:19 -0700 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.11.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 7/13/21 10:29 PM, Srinivas Neeli wrote: > Hi Guenter, > > If you are fine with my justification, I will send v2 with update code. > We have at least one more watchdog driver with open/closed window concepts. This is not a "pretimeout". Please see drivers/watchdog/rti_wdt.c for an example on how to handle this; essentially you have to set min_hw_heartbeat_ms to the value of the closed window timeout. The watchdog core then handles the mechanics. You can not use "pretimeout" to set the "closed" window size; this is an ABI abuse. There is no standard ABI for this, so if you want to have it configurable it would have to be a module parameter. Guenter > Thanks > Srinivas Neeli. > > *From:* Srinivas Neeli > *Sent:* Wednesday, June 9, 2021 12:57 PM > *To:* Guenter Roeck ; Shubhrajyoti Datta ; Srinivas Goud ; Michal Simek > *Cc:* wim@linux-watchdog.org; linux-watchdog@vger.kernel.org; linux-kernel@vger.kernel.org; git > *Subject:* RE: [PATCH 2/3] watchdog: xilinx_wwdt: Add Versal Window watchdog mode > > Hi Guenter Roeck, > > Thanks for review. > > Versal platform contain System watchdog Timer. It supports two functions, Those are > > 1) Generic watchdog mode > > 2) Window watchdog mode > > Right now we are implementing window watchdog timer functionality in driver. > > Features of Window watchdog mode: > > - The timer contains two configurable windows( closed and open). > > - The timer has to restart only in open window. > > - If software tries to restart out side of open window it will generate a reset. > > We have a requirement for window watchdog driver, So I  implemented window watchdog in two scenarios. > > 1) With Pre-timeout > > 2) With without Pre-timeout > > *Scenario 1:* > > With pre-timeout: > > Here we will get two window concept. > > 1) closed window > > 2) Open window > > start to pre-timeout, we are calling "*closed*" window. > > From pre-timeout to timeout we are calling “*Open*” window. > > *Operations:* > > start > > keep alive(only in open window,  closed window we are ignoring) > > stop > > we don't have permission to refresh/restart our timer in closed window, So ignoring the keepalive. > > Adjusted code to generate interrupt after completion of closed window. once we cross the closed window we can restart our time anytime. > > Once we reaches to timeout , will get reset signal. > > *Advantage:* > > After getting pre-timeout notification we can reset our timer or can collect our log. > > once we get interrupt we can conclude our task is not working as expected. > > So we can takecare of our tasks. > > *Scenario 2:* > > with out pre-timeout: > > It will work like general watchdog timer. > > we can run keepalive anytime(as there is no closed window, only open window present). > > Once we reaches to time out, will get reset. > > *Operations:* > > start > > keep alive > > stop > > For more details: > > https://www.xilinx.com/support/documentation/architecture-manuals/am011-versal-acap-trm.pdf > > major comments will update in V2. > > > -----Original Message----- > > > From: Guenter Roeck > On Behalf Of Guenter Roeck > > > Sent: Thursday, May 27, 2021 8:09 PM > > > To: Srinivas Neeli >; Shubhrajyoti Datta > > > >; Srinivas Goud >; Michal Simek > > > > > > > Cc: wim@linux-watchdog.org ; linux-watchdog@vger.kernel.org ; linux- > > > kernel@vger.kernel.org ; git > > > > Subject: Re: [PATCH 2/3] watchdog: xilinx_wwdt: Add Versal Window > > > watchdog mode > > > > > > The subject is confusing. This patch does not add "Versal Window watchdog > > > mode", it adds a driver which supports the Versal Window watchdog. The > > > subject should be something like "watchdog: Add Versal Window watchdog > > > driver". > > > > > > On 5/27/21 2:57 AM, Srinivas Neeli wrote: > > > > Versal watchdog driver uses Window watchdog mode. Window watchdog > > > > timer(WWDT) contains closed(first) and open(second) window with > > > > 32 bit width. WWDT will generate an interrupt after the first window > > > > timeout and reset signal after the second window timeout. Timeout and > > > > Pre-timeout configuration, Stop and Refresh trigger only in open > > > > window. > > > > > > Does that mean that userspace can not send a keepalive before the > > > pretimeout expires ? That is not how this is supposed to work. If that is the > > > case, this is not a pretimeout. Pretimeout is supposed to be used for > > > emergency handling, such as triggering a crash dump. The above description > > > as well as the code suggests that an interrupt is all but mandatory. > > > > > > Assuming that is all the case, ie that keepalive is only possible after the > > > interrupt was received, and that timeout updates are also only possible after > > > an interrupt was received, one possible handling would to record that a > > > keepalive was received, and to record that a request to update the timeout > > > was received if that happens while the window is closed. Then, when the > > > interrupt is received, those actions can be applied. Otherwise, if there was > > > no keepalive request prior to the interrupt, the interrupt handler would call > > > watchdog_notify_pretimeout(). > > > > > > Of course, this is all just guesswork. > > > > > > More comments below. > > > > > > Guenter > > > > > > > > > > > Signed-off-by: Srinivas Neeli > > > > > --- > > > >   drivers/watchdog/Kconfig       |  16 ++ > > > >   drivers/watchdog/Makefile      |   1 + > > > >   drivers/watchdog/xilinx_wwdt.c | 382 > > > +++++++++++++++++++++++++++++++++ > > > >   3 files changed, 399 insertions(+) > > > >   create mode 100644 drivers/watchdog/xilinx_wwdt.c > > > > > > > > diff --git a/drivers/watchdog/Kconfig b/drivers/watchdog/Kconfig index > > > > 355100dad60a..2ed17f278783 100644 > > > > --- a/drivers/watchdog/Kconfig > > > > +++ b/drivers/watchdog/Kconfig > > > > @@ -307,6 +307,22 @@ config XILINX_WATCHDOG > > > >            To compile this driver as a module, choose M here: the > > > >            module will be called of_xilinx_wdt. > > > > > > > > +config XILINX_WINDOW_WATCHDOG > > > > +      tristate "Xilinx Window Watchdog timer" > > > > +      depends on HAS_IOMEM > > > > +      select WATCHDOG_CORE > > > > +      help > > > > +        Window Watchdog driver for the versal_wwdt ip core. > > > > +        Window watchdog timer(WWDT) contains closed(first) and > > > > +        open(second) window with 32 bit width. WWDT will generate > > > > +        an interrupt after the first window timeout and reset > > > > +        signal after the second window timeout. Timeout and > > > > +        Pre-timeout configuration, Stop and Refresh trigger > > > > +        only in open window. > > > > + > > > > +        To compile this driver as a module, choose M here: the > > > > +        module will be called xilinx_wwdt. > > > > + > > > >   config ZIIRAVE_WATCHDOG > > > >          tristate "Zodiac RAVE Watchdog Timer" > > > >          depends on I2C > > > > diff --git a/drivers/watchdog/Makefile b/drivers/watchdog/Makefile > > > > index a7eade8b4d45..97d10c3d39c7 100644 > > > > --- a/drivers/watchdog/Makefile > > > > +++ b/drivers/watchdog/Makefile > > > > @@ -148,6 +148,7 @@ obj-$(CONFIG_M54xx_WATCHDOG) += > > > m54xx_wdt.o > > > > > > > >   # MicroBlaze Architecture > > > >   obj-$(CONFIG_XILINX_WATCHDOG) += of_xilinx_wdt.o > > > > +obj-$(CONFIG_XILINX_WINDOW_WATCHDOG) += xilinx_wwdt.o > > > > > > > >   # MIPS Architecture > > > >   obj-$(CONFIG_ATH79_WDT) += ath79_wdt.o diff --git > > > > a/drivers/watchdog/xilinx_wwdt.c b/drivers/watchdog/xilinx_wwdt.c new > > > > file mode 100644 index 000000000000..8fa2cb2225e8 > > > > --- /dev/null > > > > +++ b/drivers/watchdog/xilinx_wwdt.c > > > > @@ -0,0 +1,382 @@ > > > > +// SPDX-License-Identifier: GPL-2.0 > > > > +/* > > > > + * Window Watchdog Device Driver for Xilinx Versal WWDT > > > > + * > > > > + * (C) Copyright 2021 Xilinx, Inc. > > > > + */ > > > > + > > > > +#include > > > > +#include > > > > +#include > > > > +#include > > > > +#include > > > > +#include > > > > +#include > > > > +#include > > > > + > > > > +#define XWWDT_DEFAULT_TIMEOUT           40 > > > > +#define XWWDT_MIN_TIMEOUT    1 > > > > +#define XWWDT_MAX_TIMEOUT   42 > > > > + > > > > +/* Register offsets for the WWdt device */ > > > > +#define XWWDT_MWR_OFFSET      0x00 > > > > +#define XWWDT_ESR_OFFSET          0x04 > > > > +#define XWWDT_FCR_OFFSET          0x08 > > > > +#define XWWDT_FWR_OFFSET        0x0c > > > > +#define XWWDT_SWR_OFFSET        0x10 > > > > + > > > > +/* Master Write Control Register Masks */ > > > > +#define XWWDT_MWR_MASK                         BIT(0) > > > > + > > > > +/* Enable and Status Register Masks */ > > > > +#define XWWDT_ESR_WINT_MASK BIT(16) > > > > +#define XWWDT_ESR_WSW_MASK BIT(8) > > > > +#define XWWDT_ESR_WEN_MASK BIT(0) > > > > + > > > > +/* Function control Register Masks */ > > > > +#define XWWDT_SBC_MASK                            0xFF00 > > > > +#define XWWDT_SBC_SHIFT                             16 > > > > +#define XWWDT_BSS_MASK                             0xC0 > > > > + > > > > +static int wwdt_timeout; > > > > + > > > > +module_param(wwdt_timeout, int, 0644); > > > MODULE_PARM_DESC(wwdt_timeout, > > > > +                      "Watchdog time in seconds. (default=" > > > > +                      __MODULE_STRING(XWWDT_DEFAULT_TIMEOUT) ")"); > > > > + > > > > +struct xwwdt_device { > > > > +      void __iomem *base; > > > > +      spinlock_t spinlock; /* spinlock for register handling */ > > > > +      struct watchdog_device xilinx_wwdt_wdd; > > > > +      struct clk *clk; > > > > +      int irq; > > > > +}; > > > > + > > > > +static int is_wwdt_in_closed_window(struct watchdog_device *wdd) > > > > > > should return bool > > Will update in V2. > > > > > > > +{ > > > > +      u32 control_status_reg; > > > > +      struct xwwdt_device *xdev = watchdog_get_drvdata(wdd); > > > > + > > > > +      spin_lock(&xdev->spinlock); > > > > +      control_status_reg = ioread32(xdev->base + XWWDT_ESR_OFFSET); > > > > +      spin_unlock(&xdev->spinlock); > > > > +      if (control_status_reg & XWWDT_ESR_WEN_MASK) > > > > +                      if (!(control_status_reg & XWWDT_ESR_WSW_MASK)) > > > > +                                      return 0; > > > > + > > > > +      return 1; > > > > > > Can be written as expresion without if statement > > Will update in V2 > > > > > > > +} > > > > + > > > > +static int xilinx_wwdt_start(struct watchdog_device *wdd) { > > > > +      struct xwwdt_device *xdev = watchdog_get_drvdata(wdd); > > > > +      struct watchdog_device *xilinx_wwdt_wdd = &xdev- > > > >xilinx_wwdt_wdd; > > > > +      u64 time_out, pre_timeout, count; > > > > +      u32 control_status_reg, fcr; > > > > +      int ret; > > > > + > > > > +      count = clk_get_rate(xdev->clk); > > > > +      if (!count) > > > > +                      return -EINVAL; > > > > + > > > Is there a reason to believe that the clock rate can change ? > > > If not I would suggest to read it once and store it in struct xwwdt_device. > > Will update in V2. > > > > > > > +      /* Calculate timeout count */ > > > > +      pre_timeout = count * wdd->pretimeout; > > > > +      time_out = count * wdd->timeout; > > > > +      if (!watchdog_active(xilinx_wwdt_wdd)) { > > > > +                      ret  = clk_enable(xdev->clk); > > > > > > This is at the very least confusing. > > > The last action in the probe function is to call clk_disable_unprepare(), > > > meaning the clock should not be prepared here. How can it be enabled > > > without being prepared ? > > Will update in V2 > > > > > > > +                      if (ret) { > > > > +                                      dev_err(wdd->parent, "Failed to enable clock\n"); > > > > +                                      return ret; > > > > +                      } > > > > +      } > > > > + > > > I think it would be better to separate the functions to start/stop the clock > > > from the function to update/enable the watchdog. The use of > > > watchdog_active() combined with > > > clk_enable/clk_disable/clk_prepare_enable/clk_disable_unprepare > > > is confusing and makes it all but impossible to review the driver. > > > > > > > +      spin_lock(&xdev->spinlock); > > > > +      iowrite32(XWWDT_MWR_MASK, xdev->base + > > > XWWDT_MWR_OFFSET); > > > > +      iowrite32(~(u32)XWWDT_ESR_WEN_MASK, > > > > +                        xdev->base + XWWDT_ESR_OFFSET); > > > > + > > > > +      if (pre_timeout) { > > > > +                      iowrite32((u32)(time_out - pre_timeout), > > > > +                                        xdev->base + XWWDT_FWR_OFFSET); > > > > +                      iowrite32((u32)pre_timeout, xdev->base + > > > XWWDT_SWR_OFFSET); > > > > +                      fcr = ioread32(xdev->base + XWWDT_SWR_OFFSET); > > > > +                      fcr = (fcr >> XWWDT_SBC_SHIFT) & XWWDT_SBC_MASK; > > > > +                      fcr = fcr | XWWDT_BSS_MASK; > > > > +                      iowrite32(fcr, xdev->base + XWWDT_FCR_OFFSET); > > > > +      } else { > > > > +                      iowrite32((u32)pre_timeout, > > > > +                                        xdev->base + XWWDT_FWR_OFFSET); > > > > +                      iowrite32((u32)time_out, xdev->base + > > > XWWDT_SWR_OFFSET); > > > > +                      iowrite32(0x0, xdev->base + XWWDT_FCR_OFFSET); > > > > +      } > > > > + > > > > +      /* Enable the window watchdog timer */ > > > > +      control_status_reg = ioread32(xdev->base + XWWDT_ESR_OFFSET); > > > > +      control_status_reg |= XWWDT_ESR_WEN_MASK; > > > > +      iowrite32(control_status_reg, xdev->base + XWWDT_ESR_OFFSET); > > > > + > > > > +      spin_unlock(&xdev->spinlock); > > > > + > > > > +      dev_dbg(xilinx_wwdt_wdd->parent, "Watchdog Started!\n"); > > > > + > > > > +      return 0; > > > > +} > > > > + > > > > +static int xilinx_wwdt_stop(struct watchdog_device *wdd) { > > > > +      struct xwwdt_device *xdev = watchdog_get_drvdata(wdd); > > > > +      struct watchdog_device *xilinx_wwdt_wdd = &xdev- > > > >xilinx_wwdt_wdd; > > > > + > > > > +      if (!is_wwdt_in_closed_window(wdd)) { > > > > +                      dev_warn(xilinx_wwdt_wdd->parent, "timer in closed > > > window"); > > > > +                      return -EINVAL; > > > > +      } > > > > + > > > > +      spin_lock(&xdev->spinlock); > > > > + > > > > +      iowrite32(XWWDT_MWR_MASK, xdev->base + > > > XWWDT_MWR_OFFSET); > > > > +      /* Disable the Window watchdog timer */ > > > > +      iowrite32(~(u32)XWWDT_ESR_WEN_MASK, > > > > +                        xdev->base + XWWDT_ESR_OFFSET); > > > > + > > > > +      spin_unlock(&xdev->spinlock); > > > > + > > > > +      if (watchdog_active(xilinx_wwdt_wdd)) > > > > +                      clk_disable(xdev->clk); > > > > + > > > > > > The stop function won't be called if the watchdog is not running, ie if > > > watchdog_active() returns false. > > > I don't undeerstand the logic of clock handling in this driver. > > > More on that below. > > > > > > > +      dev_dbg(xilinx_wwdt_wdd->parent, "Watchdog Stopped!\n"); > > > > + > > > > +      return 0; > > > > +} > > > > + > > > > +static int xilinx_wwdt_keepalive(struct watchdog_device *wdd) { > > > > +      u32 control_status_reg; > > > > +      struct xwwdt_device *xdev = watchdog_get_drvdata(wdd); > > > > + > > > > +      /* Refresh in open window is ignored */ > > > > +      if (!is_wwdt_in_closed_window(wdd)) > > > > +                      return 0; > > > > + > > > This is dangerous. There is no reason for userspace to adhere to these > > > restrictions. > > > > > > > +      spin_lock(&xdev->spinlock); > > > > + > > > > +      iowrite32(XWWDT_MWR_MASK, xdev->base + > > > XWWDT_MWR_OFFSET); > > > > +      control_status_reg = ioread32(xdev->base + XWWDT_ESR_OFFSET); > > > > +      control_status_reg |= XWWDT_ESR_WINT_MASK; > > > > +      control_status_reg &= ~XWWDT_ESR_WSW_MASK; > > > > +      iowrite32(control_status_reg, xdev->base + XWWDT_ESR_OFFSET); > > > > +      control_status_reg = ioread32(xdev->base + XWWDT_ESR_OFFSET); > > > > +      control_status_reg |= XWWDT_ESR_WSW_MASK; > > > > +      iowrite32(control_status_reg, xdev->base + XWWDT_ESR_OFFSET); > > > > + > > > > +      spin_unlock(&xdev->spinlock); > > > > + > > > > +      return 0; > > > > +} > > > > + > > > > +static int xilinx_wwdt_set_timeout(struct watchdog_device *wdd, > > > > +                                                         unsigned int new_time) > > > > +{ > > > > +      u32 ret = 0; > > > > +      struct xwwdt_device *xdev = watchdog_get_drvdata(wdd); > > > > +      struct watchdog_device *xilinx_wwdt_wdd = &xdev- > > > >xilinx_wwdt_wdd; > > > > + > > > > +      if (!is_wwdt_in_closed_window(wdd)) { > > > > +                      dev_warn(xilinx_wwdt_wdd->parent, "timer in closed > > > window"); > > > > +                      return -EINVAL; > > > > +      } > > > > + > > > > > > So userspace can clog the log by continuously trying to set the timeout ? > > > > > > Also, again, this is dangerous. Userspace does not know the window size. > > user can configure window size. > > > > > > > > > > +      if (new_time < XWWDT_MIN_TIMEOUT || > > > > +          new_time > XWWDT_MAX_TIMEOUT) { > > > > +                      dev_warn(xilinx_wwdt_wdd->parent, > > > > +                                      "timeout value must be %d<=x<=%d, using %d\n", > > > > +                                      XWWDT_MIN_TIMEOUT, > > > > +                                      XWWDT_MAX_TIMEOUT, new_time); > > > > +                      return -EINVAL; > > > > +      } > > > > > > This is handled by the watchdog core. > > > > > > > + > > > > +      wdd->timeout = new_time; > > > > +      wdd->pretimeout = 0; > > > > + > > > > +      if (watchdog_active(xilinx_wwdt_wdd)) { > > > > +                      ret = xilinx_wwdt_start(wdd); > > > > +                      if (ret) > > > > +                                      dev_dbg(xilinx_wwdt_wdd->parent, "timer start > > > failed"); > > > > +      } > > > > + > > > > +      return ret; > > > > +} > > > > + > > > > +static int xilinx_wwdt_set_pretimeout(struct watchdog_device *wdd, > > > > +                                                            u32 new_pretimeout) > > > > +{ > > > > +      u32 ret = 0; > > > > +      struct xwwdt_device *xdev = watchdog_get_drvdata(wdd); > > > > +      struct watchdog_device *xilinx_wwdt_wdd = &xdev- > > > >xilinx_wwdt_wdd; > > > > + > > > > +      if (!is_wwdt_in_closed_window(wdd)) { > > > > +                      dev_warn(xilinx_wwdt_wdd->parent, "timer in closed > > > window"); > > > > +                      return -EINVAL; > > > > +      } > > > > > > This restriction is not only dangerous but confusing, and simply unacceptable. > > > Userspace will get -EINVAL with no idea what is wrong. > > > A watchdog daemon will bail out for no good reason. > > > > > > > + > > > > +      if (new_pretimeout < wdd->min_timeout || > > > > +          new_pretimeout >= wdd->timeout) > > > > +                      return -EINVAL; > > > > + > > > This is handled by the watchdog core. > > > > > > > +      wdd->pretimeout = new_pretimeout; > > > > + > > > > +      if (watchdog_active(xilinx_wwdt_wdd)) { > > > > +                      ret = xilinx_wwdt_start(wdd); > > > > +                      if (ret) > > > > +                                      dev_dbg(xilinx_wwdt_wdd->parent, "timer start > > > failed"); > > > > +      } > > > > + > > > > +      return ret; > > > > +} > > > > + > > > > +static void xwwdt_clk_disable_unprepare(void *data) { > > > > +      clk_disable_unprepare(data); > > > > +} > > > > + > > > > +static irqreturn_t xilinx_wwdt_isr(int irq, void *wdog_arg) { > > > > +      struct xwwdt_device *xdev = wdog_arg; > > > > + > > > > +      watchdog_notify_pretimeout(&xdev->xilinx_wwdt_wdd); > > > > + > > > > +      return IRQ_HANDLED; > > > > +} > > > > + > > > > +static const struct watchdog_info xilinx_wwdt_ident = { > > > > +      .options = WDIOF_MAGICCLOSE | > > > > +                         WDIOF_KEEPALIVEPING | > > > > +                         WDIOF_SETTIMEOUT, > > > > +      .firmware_version = 1, > > > > +      .identity = "xlnx_window watchdog", > > > > +}; > > > > + > > > > +static const struct watchdog_info xilinx_wwdt_pretimeout_ident = { > > > > +      .options = WDIOF_MAGICCLOSE | > > > > +                         WDIOF_KEEPALIVEPING | > > > > +                         WDIOF_PRETIMEOUT | > > > > +                         WDIOF_SETTIMEOUT, > > > > +      .firmware_version = 1, > > > > +      .identity = "xlnx_window watchdog", > > > > +}; > > > > + > > > > +static const struct watchdog_ops xilinx_wwdt_ops = { > > > > +      .owner = THIS_MODULE, > > > > +      .start = xilinx_wwdt_start, > > > > +      .stop = xilinx_wwdt_stop, > > > > +      .ping = xilinx_wwdt_keepalive, > > > > +      .set_timeout = xilinx_wwdt_set_timeout, > > > > +      .set_pretimeout = xilinx_wwdt_set_pretimeout, }; > > > > + > > > > +static int xwwdt_probe(struct platform_device *pdev) { > > > > +      struct device *dev = &pdev->dev; > > > > +      struct watchdog_device *xilinx_wwdt_wdd; > > > > +      struct xwwdt_device *xdev; > > > > +      u32 pre_timeout = 0; > > > > +      int ret; > > > > + > > > > +      xdev = devm_kzalloc(dev, sizeof(*xdev), GFP_KERNEL); > > > > +      if (!xdev) > > > > +                      return -ENOMEM; > > > > + > > > > +      xilinx_wwdt_wdd = &xdev->xilinx_wwdt_wdd; > > > > +      xilinx_wwdt_wdd->info = &xilinx_wwdt_ident; > > > > +      xilinx_wwdt_wdd->ops = &xilinx_wwdt_ops; > > > > +      xilinx_wwdt_wdd->parent = dev; > > > > + > > > > +      xdev->base = devm_platform_ioremap_resource(pdev, 0); > > > > +      if (IS_ERR(xdev->base)) > > > > +                      return PTR_ERR(xdev->base); > > > > + > > > > +      ret = of_property_read_u32(dev->of_node, "pretimeout-sec", > > > > +                                                         &pre_timeout); > > > > +      if (ret) > > > > +                      dev_dbg(dev, > > > > +                                      "Parameter \"pretimeout-sec\" not found\n"); > > > > + > > > > +      xdev->clk = devm_clk_get(dev, NULL); > > > > +      if (IS_ERR(xdev->clk)) > > > > +                      return PTR_ERR(xdev->clk); > > > > + > > > > +      ret = clk_get_rate(xdev->clk); > > > > +      if (!ret) > > > > +                      return -EINVAL; > > > > + > > > > +      ret = clk_prepare_enable(xdev->clk); > > > > +      if (ret) { > > > > +                      dev_err(dev, "unable to enable clock\n"); > > > > +                      return ret; > > > > +      } > > > > +      ret = devm_add_action_or_reset(dev, > > > xwwdt_clk_disable_unprepare, > > > > +                                                             xdev->clk); > > > > +      if (ret) > > > > +                      goto err_clk_disable; > > > > + > > > > > > Seems pointless. What happens when you unload the driver ? > > > > > > > +      xilinx_wwdt_wdd->pretimeout = pre_timeout; > > > > +      xilinx_wwdt_wdd->timeout = XWWDT_DEFAULT_TIMEOUT; > > > > +      xilinx_wwdt_wdd->min_timeout = XWWDT_MIN_TIMEOUT; > > > > +      xilinx_wwdt_wdd->max_timeout = XWWDT_MAX_TIMEOUT; > > > > + > > > > +      xdev->irq = platform_get_irq_byname(pdev, "wdt"); > > > > +      if (xdev->irq < 0) { > > > > +                      ret = xdev->irq; > > > > +                      goto err_clk_disable; > > > > +      } > > > > + > > > > +      if (!devm_request_irq(dev, xdev->irq, xilinx_wwdt_isr, > > > > +                                            0, dev_name(dev), xdev)) { > > > > +                      xilinx_wwdt_wdd->info = &xilinx_wwdt_pretimeout_ident; > > > > +      } > > > > + > > > > +      ret = watchdog_init_timeout(xilinx_wwdt_wdd, > > > > +                                                          wwdt_timeout, &pdev->dev); > > > > +      if (ret) > > > > +                      dev_info(&pdev->dev, "Configured default timeout > > > value\n"); > > > > + > > > > +      spin_lock_init(&xdev->spinlock); > > > > +      watchdog_set_drvdata(xilinx_wwdt_wdd, xdev); > > > > + > > > > +      ret = devm_watchdog_register_device(dev, xilinx_wwdt_wdd); > > > > +      if (ret) > > > > +                      goto err_clk_disable; > > > > + > > > At this point the watchdog is fully instantiated, and userspace may have > > > enabled it. > > > > > > > +      clk_disable_unprepare(xdev->clk); > > > > + > > > And now its clock is getting stopped. Actually, it is getting unprepared. > > > Does this even work ? > > > > > > > +      dev_info(dev, "Xilinx Window Watchdog Timer with timeout %ds\n", > > > > +                      xilinx_wwdt_wdd->timeout); > > > > + > > > > +      return 0; > > > > + > > > > +err_clk_disable: > > > > +      clk_disable_unprepare(xdev->clk); > > > > > > devm_add_action_or_reset() already handles this. > > > > > > > +      return ret; > > > > +} > > > > + > > > > +/* Mat for of_platform binding */ > > > > +static const struct of_device_id xwwdt_of_match[] = { > > > > +      { .compatible = "xlnx,versal-wwdt-1.0", }, > > > > +      {}, > > > > +}; > > > > +MODULE_DEVICE_TABLE(of, xwwdt_of_match); > > > > + > > > > +static struct platform_driver xwwdt_driver = { > > > > +      .probe = xwwdt_probe, > > > > +      .driver = { > > > > +                      .name = "Xilinx Window Watchdog", > > > > +                      .of_match_table = xwwdt_of_match, > > > > +      }, > > > > +}; > > > > + > > > > +module_platform_driver(xwwdt_driver); > > > > + > > > > +MODULE_AUTHOR("Neeli Srinivas >"); > > > > +MODULE_DESCRIPTION("Xilinx Window Watchdog driver"); > > > > +MODULE_LICENSE("GPL"); > > > > > > Thanks > > Srinivas Neeli. >