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Message-ID: <524DB86E.4010900@overkiz.com>
Date: Thu, 03 Oct 2013 20:33:18 +0200
From: boris brezillon <b.brezillon@...rkiz.com>
To: boris brezillon <b.brezillon@...rkiz.com>,
Guenter Roeck <linux@...ck-us.net>
CC: Mark Rutland <mark.rutland@....com>, devicetree@...r.kernel.org,
Russell King <linux@....linux.org.uk>,
linux-doc@...r.kernel.org, Pawel Moll <pawel.moll@....com>,
Ian Campbell <ijc+devicetree@...lion.org.uk>,
Stephen Warren <swarren@...dotorg.org>,
Nicolas Ferre <nicolas.ferre@...el.com>,
linux-kernel@...r.kernel.org,
Rob Herring <rob.herring@...xeda.com>,
Yang Wenyou <wenyou.yang@...el.com>,
Wim Van Sebroeck <wim@...ana.be>,
Fabio Porcedda <fabio.porcedda@...il.com>,
linux-arm-kernel@...ts.infradead.org,
Rob Landley <rob@...dley.net>,
Guenter Roeck <groeck7@...il.com>,
linux-watchdog@...r.kernel.org
Subject: Re: [PATCH 1/4] watchdog: at91sam9_wdt: better watchdog support
On 03/10/2013 19:55, boris brezillon wrote:
> Hi Guenter,
>
> On 03/10/2013 19:31, Guenter Roeck wrote:
>> On Thu, Oct 03, 2013 at 02:19:18PM +0200, Boris BREZILLON wrote:
>>> The at91sam9 watchdog timer can only be configured once, and the current
>>> implementation tries to configure it in a static way:
>>> - 2 seconds timeout
>>> - wdt restart every 500ms
>>>
>>> If the timer has already been configured with different values, it
>>> returns an
>>> error and do not create any watchdog device.
>>>
>>> This is not critical if the watchdog is disabled, but if it has been
>>> enabled with
>>> different timeout values it will lead to a SoC reset.
>>>
>>> This patch series tries to address this issue by adapting the
>>> heartbeat value
>>> according the WDT timer config:
>>> - it first tries to configure the timer as requested.
>>> - if it fails it fallbacks to the current config, adapting its
>>> heartbeat timer
>>> to the needs
>>>
>>> This patch series also move to a dynamically allocated at91wdt device
>>> instead
>>> of the static instance.
>>>
>>> It adds a new at91 wdt type: software. This new type make use of the
>>> at91 wdt
>>> interrupt to trigger a software reboot.
>>>
>>> Finally it adds several properties to the device tree bindings.
>>>
>>> Signed-off-by: Boris BREZILLON <b.brezillon@...rkiz.com>
>> Hi Boris,
>>
>> deeper dive this time ...
>>
>>> ---
>>> drivers/watchdog/at91sam9_wdt.c | 300
>>> ++++++++++++++++++++++++++++-----------
>>> 1 file changed, 217 insertions(+), 83 deletions(-)
>>>
>>> diff --git a/drivers/watchdog/at91sam9_wdt.c
>>> b/drivers/watchdog/at91sam9_wdt.c
>>> index be37dde..8f44528 100644
>>> --- a/drivers/watchdog/at91sam9_wdt.c
>>> +++ b/drivers/watchdog/at91sam9_wdt.c
>>> @@ -19,11 +19,13 @@
>>> #include <linux/errno.h>
>>> #include <linux/init.h>
>>> +#include <linux/interrupt.h>
>>> #include <linux/io.h>
>>> #include <linux/kernel.h>
>>> #include <linux/module.h>
>>> #include <linux/moduleparam.h>
>>> #include <linux/platform_device.h>
>>> +#include <linux/reboot.h>
>>> #include <linux/types.h>
>>> #include <linux/watchdog.h>
>>> #include <linux/jiffies.h>
>>> @@ -31,22 +33,33 @@
>>> #include <linux/bitops.h>
>>> #include <linux/uaccess.h>
>>> #include <linux/of.h>
>>> +#include <linux/of_irq.h>
>>> #include "at91sam9_wdt.h"
>>> #define DRV_NAME "AT91SAM9 Watchdog"
>>> -#define wdt_read(field) \
>>> - __raw_readl(at91wdt_private.base + field)
>>> -#define wdt_write(field, val) \
>>> - __raw_writel((val), at91wdt_private.base + field)
>>> +#define wdt_read(wdt, field) \
>>> + __raw_readl((wdt)->base + (field))
>>> +#define wdt_write(wtd, field, val) \
>>> + __raw_writel((val), (wdt)->base + (field))
>>> /* AT91SAM9 watchdog runs a 12bit counter @ 256Hz,
>>> * use this to convert a watchdog
>>> * value from/to milliseconds.
>>> */
>>> -#define ms_to_ticks(t) (((t << 8) / 1000) - 1)
>>> -#define ticks_to_ms(t) (((t + 1) * 1000) >> 8)
>>> +#define ticks_to_hz_rounddown(t) ((((t) + 1) * HZ) >> 8)
>>> +#define ticks_to_hz_roundup(t) (((((t) + 1) * HZ) + 255) >> 8)
>>> +#define ticks_to_secs(t) (((t) + 1) >> 8)
>>> +#define secs_to_ticks(s) (((s) << 8) - 1)
>>> +
>>> +#define WDT_MR_RESET 0x3FFF2FFF
>>> +
>>> +/* Watchdog max counter value in ticks */
>>> +#define WDT_COUNTER_MAX_TICKS 0xFFF
>>> +
>>> +/* Watchdog max delta/value in secs */
>>> +#define WDT_COUNTER_MAX_SECS ticks_to_secs(WDT_COUNTER_MAX_TICKS)
>>> /* Hardware timeout in seconds */
>>> #define WDT_HW_TIMEOUT 2
>>> @@ -66,23 +79,40 @@ module_param(nowayout, bool, 0);
>>> MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started "
>>> "(default=" __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
>>> -static struct watchdog_device at91_wdt_dev;
>>> -static void at91_ping(unsigned long data);
>>> -
>>> -static struct {
>>> +#define to_wdt(wdd) container_of(wdd, struct at91wdt, wdd)
>>> +struct at91wdt {
>>> + struct watchdog_device wdd;
>>> void __iomem *base;
>>> unsigned long next_heartbeat; /* the next_heartbeat for the
>>> timer */
>>> struct timer_list timer; /* The timer that pings the
>>> watchdog */
>>> -} at91wdt_private;
>>> + u32 mr;
>>> + u32 mr_mask;
>>> + unsigned long heartbeat; /* WDT heartbeat in jiffies */
>>> + bool nowayout;
>>> + unsigned int irq;
>>> +};
>>> /*
>>> .........................................................................
>>> */
>>> +static irqreturn_t wdt_interrupt(int irq, void *dev_id)
>>> +{
>>> + struct at91wdt *wdt = (struct at91wdt *)dev_id;
>>> +
>>> + if (wdt_read(wdt, AT91_WDT_SR)) {
>>> + pr_crit("at91sam9 WDT software reset\n");
>>> + emergency_restart();
>>> + pr_crit("Reboot didn't ?????\n");
>>> + }
>>> +
>>> + return IRQ_HANDLED;
>>> +}
>>> +
>>> /*
>>> * Reload the watchdog timer. (ie, pat the watchdog)
>>> */
>>> -static inline void at91_wdt_reset(void)
>>> +static inline void at91_wdt_reset(struct at91wdt *wdt)
>>> {
>>> - wdt_write(AT91_WDT_CR, AT91_WDT_KEY | AT91_WDT_WDRSTT);
>>> + wdt_write(wdt, AT91_WDT_CR, AT91_WDT_KEY | AT91_WDT_WDRSTT);
>>> }
>>> /*
>>> @@ -90,26 +120,20 @@ static inline void at91_wdt_reset(void)
>>> */
>>> static void at91_ping(unsigned long data)
>>> {
>>> - if (time_before(jiffies, at91wdt_private.next_heartbeat) ||
>>> - (!watchdog_active(&at91_wdt_dev))) {
>>> - at91_wdt_reset();
>>> - mod_timer(&at91wdt_private.timer, jiffies + WDT_TIMEOUT);
>>> + struct at91wdt *wdt = (struct at91wdt *)data;
>>> + if (time_before(jiffies, wdt->next_heartbeat) ||
>>> + !watchdog_active(&wdt->wdd)) {
>>> + at91_wdt_reset(wdt);
>>> + mod_timer(&wdt->timer, jiffies + wdt->heartbeat);
>>> } else
>>> pr_crit("I will reset your machine !\n");
>>> }
>>> static int at91_wdt_ping(struct watchdog_device *wdd)
>>> {
>>> + struct at91wdt *wdt = to_wdt(wdd);
>>> /* calculate when the next userspace timeout will be */
>>> - at91wdt_private.next_heartbeat = jiffies + wdd->timeout * HZ;
>>> - return 0;
>>> -}
>>> -
>>> -static int at91_wdt_start(struct watchdog_device *wdd)
>>> -{
>>> - /* calculate the next userspace timeout and modify the timer */
>>> - at91_wdt_ping(wdd);
>>> - mod_timer(&at91wdt_private.timer, jiffies + WDT_TIMEOUT);
>>> + wdt->next_heartbeat = jiffies + wdd->timeout * HZ;
>>> return 0;
>>> }
>>> @@ -125,36 +149,84 @@ static int at91_wdt_set_timeout(struct
>>> watchdog_device *wdd, unsigned int new_ti
>> at91_wdt_set_timeout only sets the new timeout but does not update
>> next_heartbeat. That is ok if the timeout decreases, but if it is
>> increased (say, from 1 second to 1 minute) it might result in a missed
>> ping as userspace will subsequently believe that the new (larger)
>> timeout was accepted by the driver. So I think you should also call
>> at91_wdt_ping here or set wdt->next_heartbeat directly.
> Absolutely, I'll call at91_wdt_ping (or start as it will be renamed).
>
>>> return 0;
>>> }
>>> -/*
>>> - * Set the watchdog time interval in 1/256Hz (write-once)
>>> - * Counter is 12 bit.
>>> - */
>>> -static int at91_wdt_settimeout(unsigned int timeout)
>>> +static int at91_wdt_init(struct platform_device *pdev, struct
>>> at91wdt *wdt)
>>> {
>>> - unsigned int reg;
>>> - unsigned int mr;
>>> -
>>> - /* Check if disabled */
>>> - mr = wdt_read(AT91_WDT_MR);
>>> - if (mr & AT91_WDT_WDDIS) {
>>> - pr_err("sorry, watchdog is disabled\n");
>>> - return -EIO;
>>> + u32 tmp;
>>> + u32 delta;
>>> + u32 value;
>>> + int err;
>>> + u32 mask = wdt->mr_mask;
>>> + unsigned long min_heartbeat = 1;
>>> +
>>> + tmp = wdt_read(wdt, AT91_WDT_MR);
>>> + if ((tmp & mask) != (wdt->mr & mask)) {
>>> + if (tmp == WDT_MR_RESET) {
>>> + wdt_write(wdt, AT91_WDT_MR, wdt->mr);
>>> + tmp = wdt_read(wdt, AT91_WDT_MR);
>>> + }
>>> }
>>> - /*
>>> - * All counting occurs at SLOW_CLOCK / 128 = 256 Hz
>>> - *
>>> - * Since WDV is a 12-bit counter, the maximum period is
>>> - * 4096 / 256 = 16 seconds.
>>> - */
>>> - reg = AT91_WDT_WDRSTEN /* causes watchdog reset */
>>> - /* | AT91_WDT_WDRPROC causes processor reset only */
>>> - | AT91_WDT_WDDBGHLT /* disabled in debug mode */
>>> - | AT91_WDT_WDD /* restart at any time */
>>> - | (timeout & AT91_WDT_WDV); /* timer value */
>>> - wdt_write(AT91_WDT_MR, reg);
>>> + if (tmp & AT91_WDT_WDDIS) {
>>> + if (wdt->mr & AT91_WDT_WDDIS)
>>> + return 0;
>>> + dev_err(wdt->wdd.parent, "watchdog is disabled\n");
>> Took me a while to get why you use "wdt->wdd.parent" :).
>> I would just have passed the 'dev' argument. Your call, though.
>
> I can't use wdt->wdd.dev, because the watchdog device is not registered
> yet,
> but I can use &pdev->dev instead.
> What do you prefer ?
Oops. I should have read your mail more carefully, I though you were
talking about using the dev field of the wdd struct.
I still prefer using wdt->wdd.parent or &pdev->dev rather (or declare a
struct device *dev = &pdev->dev) rather than passing an additional
'struct device *' argument.
>
>>> + return -EINVAL;
>>> + }
>>> +
>>> + value = tmp & AT91_WDT_WDV;
>>> + delta = (tmp & AT91_WDT_WDD) >> 16;
>>> +
>>> + if (delta < value)
>>> + min_heartbeat = ticks_to_hz_roundup(value - delta);
>>> +
>>> + wdt->heartbeat = ticks_to_hz_rounddown(value);
>>> + if (!wdt->heartbeat) {
>>> + dev_err(wdt->wdd.parent,
>>> + "heartbeat is too small for the system to handle it
>>> correctly\n");
>>> + return -EINVAL;
>>> + }
>>> +
>>> + if (wdt->heartbeat < min_heartbeat + 3) {
>>> + wdt->heartbeat = min_heartbeat;
>>> + dev_warn(wdt->wdd.parent,
>>> + "min heartbeat and max heartbeat might be too close for
>>> the system to handle it correctly\n");
>>> + if (wdt->heartbeat < 4)
>>> + dev_warn(wdt->wdd.parent,
>>> + "heartbeat might be too small for the system to
>>> handle it correctly\n");
>>> + } else
>>> + wdt->heartbeat -= 4;
>> That means heartbeat can be 0, correct (if min_heartbeat == 1) ?
> Yes, this is a mistake. It should be
>
> if (wdt->heartbeat < min_heartbeat + 4) {
> ...
> }
>
>> Will that work ?
> Absolutely not :)
> I'll fix it.
>
>>
>>> +
>>> + if ((tmp & AT91_WDT_WDFIEN) && wdt->irq) {
>>> + err = request_irq(wdt->irq, wdt_interrupt,
>>> + IRQF_SHARED | IRQF_IRQPOLL,
>>> + pdev->name, wdt);
>>> + if (err)
>>> + return err;
>>> + }
>>> +
>>> + if ((tmp & wdt->mr_mask) != (wdt->mr & wdt->mr_mask))
>>> + dev_warn(wdt->wdd.parent,
>>> + "watchdog already configured differently (mr = %x
>>> expecting %x)\n",
>>> + tmp & wdt->mr_mask, wdt->mr & wdt->mr_mask);
>>> +
>>> + setup_timer(&wdt->timer, at91_ping, (unsigned long)wdt);
>>> + mod_timer(&wdt->timer, jiffies + wdt->heartbeat);
>>> +
>>> + /* Try to set timeout from device tree first */
>>> + if (watchdog_init_timeout(&wdt->wdd, 0, &pdev->dev))
>>> + watchdog_init_timeout(&wdt->wdd, heartbeat, &pdev->dev);
>>> + watchdog_set_nowayout(&wdt->wdd, wdt->nowayout);
>>> + err = watchdog_register_device(&wdt->wdd);
>>> + if (err)
>>> + goto out_stop_timer;
>>> +
>>> + wdt->next_heartbeat = jiffies + wdt->wdd.timeout * HZ;
>>> return 0;
>>> +
>>> +out_stop_timer:
>>> + del_timer(&wdt->timer);
>>> + return err;
>>> }
>>> /*
>>> .........................................................................
>>> */
>>> @@ -167,63 +239,125 @@ static const struct watchdog_info
>>> at91_wdt_info = {
>>> static const struct watchdog_ops at91_wdt_ops = {
>>> .owner = THIS_MODULE,
>>> - .start = at91_wdt_start,
>>> + .start = at91_wdt_ping,
>>> .stop = at91_wdt_stop,
>>> .ping = at91_wdt_ping,
>> Notpick, but you don't need both start and ping. If both are the same,
>> providing
>> start is sufficient. Given this, it might be cleaner to name the function
>> at91_wdt_start and not provide ping.
> I'll change this too.
>
> Thanks, for catching these bugs.
>
> Regards,
>
> Boris
>
>>> .set_timeout = at91_wdt_set_timeout,
>>> };
>>> -static struct watchdog_device at91_wdt_dev = {
>>> - .info = &at91_wdt_info,
>>> - .ops = &at91_wdt_ops,
>>> - .timeout = WDT_HEARTBEAT,
>>> - .min_timeout = 1,
>>> - .max_timeout = 0xFFFF,
>>> -};
>>> +#if defined(CONFIG_OF)
>>> +static int of_at91wdt_init(struct device_node *np, struct at91wdt *wdt)
>>> +{
>>> + u32 min = 0;
>>> + u32 max = WDT_COUNTER_MAX_SECS;
>>> + const char *tmp;
>>> +
>>> + /* Get the interrupts property */
>>> + wdt->irq = irq_of_parse_and_map(np, 0);
>>> + if (!wdt->irq)
>>> + dev_warn(wdt->wdd.parent, "failed to get IRQ from DT\n");
>>> +
>>> + if (!of_property_read_u32_index(np, "atmel,max-heartbeat-sec", 0,
>>> + &max)) {
>>> + if (!max || max > WDT_COUNTER_MAX_SECS)
>>> + max = WDT_COUNTER_MAX_SECS;
>>> +
>>> + if (!of_property_read_u32_index(np, "atmel,min-heartbeat-sec",
>>> + 0, &min)) {
>>> + if (min >= max)
>>> + min = max - 1;
>>> + }
>>> + }
>>> +
>>> + min = secs_to_ticks(min);
>>> + max = secs_to_ticks(max);
>>> +
>>> + wdt->mr_mask = 0x3FFFFFFF;
>>> + wdt->mr = 0;
>>> + if (!of_property_read_string(np, "atmel,watchdog-type", &tmp) &&
>>> + !strcmp(tmp, "software")) {
>>> + wdt->mr |= AT91_WDT_WDFIEN;
>>> + wdt->mr_mask &= ~AT91_WDT_WDRPROC;
>>> + } else
>>> + wdt->mr |= AT91_WDT_WDRSTEN;
>>> +
>>> + if (!of_property_read_string(np, "atmel,reset-type", &tmp) &&
>>> + !strcmp(tmp, "proc"))
>>> + wdt->mr |= AT91_WDT_WDRPROC;
>>> +
>>> + if (of_property_read_bool(np, "atmel,disable")) {
>>> + wdt->mr |= AT91_WDT_WDDIS;
>>> + wdt->mr_mask &= AT91_WDT_WDDIS;
>>> + }
>>> +
>>> + if (of_property_read_bool(np, "atmel,idle-halt"))
>>> + wdt->mr |= AT91_WDT_WDIDLEHLT;
>>> +
>>> + if (of_property_read_bool(np, "atmel,dbg-halt"))
>>> + wdt->mr |= AT91_WDT_WDDBGHLT;
>>> +
>>> + wdt->mr |= max | ((max - min) << 16);
>>> +
>>> + return 0;
>>> +}
>>> +#else
>>> +static inline int of_at91wdt_init(struct device_node *np, struct
>>> at91wdt *wdt)
>>> +{
>>> + return 0;
>>> +}
>>> +#endif
>>> static int __init at91wdt_probe(struct platform_device *pdev)
>>> {
>>> struct resource *r;
>>> - int res;
>>> + int err;
>>> + struct at91wdt *wdt;
>>> - r = platform_get_resource(pdev, IORESOURCE_MEM, 0);
>>> - if (!r)
>>> - return -ENODEV;
>>> - at91wdt_private.base = ioremap(r->start, resource_size(r));
>>> - if (!at91wdt_private.base) {
>>> - dev_err(&pdev->dev, "failed to map registers, aborting.\n");
>>> + wdt = devm_kzalloc(&pdev->dev, sizeof(*wdt), GFP_KERNEL);
>>> + if (!wdt)
>>> return -ENOMEM;
>>> - }
>>> - at91_wdt_dev.parent = &pdev->dev;
>>> - watchdog_init_timeout(&at91_wdt_dev, heartbeat, &pdev->dev);
>>> - watchdog_set_nowayout(&at91_wdt_dev, nowayout);
>>> + wdt->mr = (WDT_HW_TIMEOUT * 256) | AT91_WDT_WDRSTEN |
>>> AT91_WDT_WDD |
>>> + AT91_WDT_WDDBGHLT | AT91_WDT_WDIDLEHLT;
>>> + wdt->mr_mask = 0x3FFFFFFF;
>>> + wdt->nowayout = nowayout;
>>> + wdt->wdd.parent = &pdev->dev;
>>> + wdt->wdd.info = &at91_wdt_info;
>>> + wdt->wdd.ops = &at91_wdt_ops;
>>> + wdt->wdd.timeout = WDT_HEARTBEAT;
>>> + wdt->wdd.min_timeout = 1;
>>> + wdt->wdd.max_timeout = 0xFFFF;
>>> - /* Set watchdog */
>>> - res = at91_wdt_settimeout(ms_to_ticks(WDT_HW_TIMEOUT * 1000));
>>> - if (res)
>>> - return res;
>>> + r = platform_get_resource(pdev, IORESOURCE_MEM, 0);
>>> + wdt->base = devm_ioremap_resource(&pdev->dev, r);
>>> + if (IS_ERR(wdt->base))
>>> + return PTR_ERR(wdt->base);
>>> +
>>> + if (pdev->dev.of_node) {
>>> + err = of_at91wdt_init(pdev->dev.of_node, wdt);
>>> + if (err)
>>> + return err;
>>> + }
>>> - res = watchdog_register_device(&at91_wdt_dev);
>>> - if (res)
>>> - return res;
>>> + err = at91_wdt_init(pdev, wdt);
>>> + if (err)
>>> + return err;
>>> - at91wdt_private.next_heartbeat = jiffies + at91_wdt_dev.timeout
>>> * HZ;
>>> - setup_timer(&at91wdt_private.timer, at91_ping, 0);
>>> - mod_timer(&at91wdt_private.timer, jiffies + WDT_TIMEOUT);
>>> + platform_set_drvdata(pdev, wdt);
>>> pr_info("enabled (heartbeat=%d sec, nowayout=%d)\n",
>>> - at91_wdt_dev.timeout, nowayout);
>>> + wdt->wdd.timeout, wdt->nowayout);
>>> return 0;
>>> }
>>> static int __exit at91wdt_remove(struct platform_device *pdev)
>>> {
>>> - watchdog_unregister_device(&at91_wdt_dev);
>>> + struct at91wdt *wdt = platform_get_drvdata(pdev);
>>> + watchdog_unregister_device(&wdt->wdd);
>>> pr_warn("I quit now, hardware will probably reboot!\n");
>>> - del_timer(&at91wdt_private.timer);
>>> + del_timer(&wdt->timer);
>>> return 0;
>>> }
>>> --
>>> 1.7.9.5
>>>
>>> --
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>
>
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