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Message-ID: <e6f75042-3b49-46f9-8679-572044eee17f@roeck-us.net>
Date: Wed, 14 Jul 2021 04:31:19 -0700
From: Guenter Roeck <linux@...ck-us.net>
To: Srinivas Neeli <sneeli@...inx.com>,
Shubhrajyoti Datta <shubhraj@...inx.com>,
Srinivas Goud <sgoud@...inx.com>,
Michal Simek <michals@...inx.com>
Cc: "wim@...ux-watchdog.org" <wim@...ux-watchdog.org>,
"linux-watchdog@...r.kernel.org" <linux-watchdog@...r.kernel.org>,
"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
git <git@...inx.com>
Subject: Re: [PATCH 2/3] watchdog: xilinx_wwdt: Add Versal Window watchdog
mode
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 <sneeli@...inx.com>
> *Sent:* Wednesday, June 9, 2021 12:57 PM
> *To:* Guenter Roeck <linux@...ck-us.net>; Shubhrajyoti Datta <shubhraj@...inx.com>; Srinivas Goud <sgoud@...inx.com>; Michal Simek <michals@...inx.com>
> *Cc:* wim@...ux-watchdog.org; linux-watchdog@...r.kernel.org; linux-kernel@...r.kernel.org; git <git@...inx.com>
> *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 <https://www.xilinx.com/support/documentation/architecture-manuals/am011-versal-acap-trm.pdf>
>
> major comments will update in V2.
>
> > -----Original Message-----
>
> > From: Guenter Roeck <groeck7@...il.com <mailto:groeck7@...il.com>> On Behalf Of Guenter Roeck
>
> > Sent: Thursday, May 27, 2021 8:09 PM
>
> > To: Srinivas Neeli <sneeli@...inx.com <mailto:sneeli@...inx.com>>; Shubhrajyoti Datta
>
> > <shubhraj@...inx.com <mailto:shubhraj@...inx.com>>; Srinivas Goud <sgoud@...inx.com <mailto:sgoud@...inx.com>>; Michal Simek
>
> > <michals@...inx.com <mailto:michals@...inx.com>>
>
> > Cc: wim@...ux-watchdog.org <mailto:wim@...ux-watchdog.org>; linux-watchdog@...r.kernel.org <mailto:linux-watchdog@...r.kernel.org>; linux-
>
> > kernel@...r.kernel.org <mailto:kernel@...r.kernel.org>; git <git@...inx.com <mailto:git@...inx.com>>
>
> > 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 <srinivas.neeli@...inx.com <mailto:srinivas.neeli@...inx.com>>
>
> > > ---
>
> > > 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 <linux/clk.h>
>
> > > +#include <linux/interrupt.h>
>
> > > +#include <linux/io.h>
>
> > > +#include <linux/ioport.h>
>
> > > +#include <linux/of_device.h>
>
> > > +#include <linux/of_address.h>
>
> > > +#include <linux/module.h>
>
> > > +#include <linux/watchdog.h>
>
> > > +
>
> > > +#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 <sneeli@...inx.com <mailto:sneeli@...inx.com>>");
>
> > > +MODULE_DESCRIPTION("Xilinx Window Watchdog driver");
>
> > > +MODULE_LICENSE("GPL");
>
> > >
>
> Thanks
>
> Srinivas Neeli.
>
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