Hello.
> On 11/26/2013 08:26 AM, Alexander Shiyan wrote:
> > This patch adds a watchdog driver for devices controlled through GPIO,
> > (Analog Devices ADM706, IC 555 etc).
> >
> > Signed-off-by: Alexander Shiyan <shc_work@xxxxxxx>
...
> > +++ b/Documentation/devicetree/bindings/watchdog/gpio-wdt.txt
> > @@ -0,0 +1,23 @@
> > +* GPIO-controlled Watchdog
> > +
> > +Required Properties:
> > +- compatible: Should contain "linux,wdt-gpio".
>
> Should ?
>
> > +- gpios: From common gpio binding; gpio connection to WDT reset pin.
> > +- wdt-gpio,hw_algo: The algorithm used by the driver. Should be one
> > + of the following values:
>
> Should ?
What wrong here?
...
> > +Example:
> > + watchdog: watchdog {
> > + /* ADM706 */
> > + compatible = "linux,wdt-gpio";
>
> Oddly enough, the bindings could be used by non-Linux operating systems,
> but who am I to argue. Fine if this is what the DT maintainers want to see.
On my opinion this mean that this is not a real hardware, but hardware emulation,
like some other driver does.
...
> > diff --git a/drivers/watchdog/gpio_wdt.c b/drivers/watchdog/gpio_wdt.c
> > new file mode 100644
> > index 0000000..c7166be
> > --- /dev/null
> > +++ b/drivers/watchdog/gpio_wdt.c
> > @@ -0,0 +1,246 @@
> > +/*
> > + * Driver for watchdog device controlled through GPIO-line
> > + *
> > + * Author: 2013, Alexander Shiyan <shc_work@xxxxxxx>
> > + *
> > + * This program is free software; you can redistribute it and/or modify
> > + * it under the terms of the GNU General Public License as published by
> > + * the Free Software Foundation; either version 2 of the License, or
> > + * (at your option) any later version.
> > + */
> > +
> > +#include <linux/err.h>
> > +#include <linux/delay.h>
> > +#include <linux/module.h>
> > +#include <linux/notifier.h>
> > +#include <linux/of_gpio.h>
> > +#include <linux/platform_device.h>
> > +#include <linux/reboot.h>
> > +#include <linux/watchdog.h>
> > +
> > +#define SOFT_TIMEOUT_MIN 1
> > +#define SOFT_TIMEOUT_DEF 60
> > +#define SOFT_TIMEOUT_MAX 0xffff
> > +
> > +enum {
> > + HW_ALGO_TOGGLE,
> > + HW_ALGO_LEVEL,
> > +};
> > +
> > +struct gpio_wdt_priv {
> > + int gpio;
> > + bool active_low;
> > + bool state;
> > + unsigned int hw_algo;
> > + unsigned int hw_margin;
> > + unsigned long last_jiffies;
> > + struct notifier_block notifier;
> > + struct timer_list timer;
> > + struct watchdog_device wdd;
> > +};
> > +
> > +static int gpio_wdt_disable(struct gpio_wdt_priv *priv)
> > +{
> > + gpio_set_value_cansleep(priv->gpio, !priv->active_low);
> > +
> > + /* Put GPIO back to tristate */
> > + if (priv->hw_algo == HW_ALGO_TOGGLE)
> > + return gpio_direction_input(priv->gpio);
> > +
> No disable for 'level' watchdogs ? Shouldn't it be set to the opposite
> of priv->state ?
>
> > + return 0;
>
> Since this is an internal function which never returns anything but 0,
> you might as well make it void.
"level" version will be disabled by
"gpio_set_value_cansleep(priv->gpio, !priv->active_low);" line above.
"return" is used by "tristate" switch.
...
> > +static void gpio_wdt_hwping(unsigned long data)
> > +{
> > + struct watchdog_device *wdd = (struct watchdog_device *)data;
> > + struct gpio_wdt_priv *priv = watchdog_get_drvdata(wdd);
> > +
> > + if (time_before(jiffies, priv->last_jiffies +
> > + msecs_to_jiffies(wdd->timeout * 1000))) {
> > + /* Restart timer */
> > + mod_timer(&priv->timer, jiffies + priv->hw_margin);
> > +
> > + switch (priv->hw_algo) {
> > + case HW_ALGO_TOGGLE:
> > + /* Toggle output pin */
> > + priv->state = !priv->state;
> > + gpio_set_value_cansleep(priv->gpio, priv->state);
> > + break;
> > + case HW_ALGO_LEVEL:
> > + /* Pulse */
> > + gpio_set_value_cansleep(priv->gpio, !priv->active_low);
> > + udelay(1);
>
> Pretty arbitrary toggle time. Should this be a property ?
What about 1/10 of hardware timeout?
...
Thanks.
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