Messages in this thread | | | Subject | Re: [PATCHv3 3/4] watchdog: rti-wdt: attach to running watchdog during probe | From | Tero Kristo <> | Date | Tue, 14 Jul 2020 09:50:22 +0300 |
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On 14/07/2020 08:15, Guenter Roeck wrote: > On 7/13/20 6:18 AM, Tero Kristo wrote: >> If the RTI watchdog is running already during probe, the driver must >> configure itself to match the HW. Window size and timeout is probed from >> hardware, and the last keepalive ping is adjusted to match it also. >> >> Signed-off-by: Tero Kristo <t-kristo@ti.com> >> --- >> drivers/watchdog/rti_wdt.c | 111 +++++++++++++++++++++++++++++++++---- >> 1 file changed, 101 insertions(+), 10 deletions(-) >> >> diff --git a/drivers/watchdog/rti_wdt.c b/drivers/watchdog/rti_wdt.c >> index d456dd72d99a..45dfc546e371 100644 >> --- a/drivers/watchdog/rti_wdt.c >> +++ b/drivers/watchdog/rti_wdt.c >> @@ -35,7 +35,11 @@ >> >> #define RTIWWDRX_NMI 0xa >> >> -#define RTIWWDSIZE_50P 0x50 >> +#define RTIWWDSIZE_50P 0x50 >> +#define RTIWWDSIZE_25P 0x500 >> +#define RTIWWDSIZE_12P5 0x5000 >> +#define RTIWWDSIZE_6P25 0x50000 >> +#define RTIWWDSIZE_3P125 0x500000 >> >> #define WDENABLE_KEY 0xa98559da >> >> @@ -48,7 +52,7 @@ >> >> #define DWDST BIT(1) >> >> -static int heartbeat; >> +static int heartbeat = DEFAULT_HEARTBEAT; >> >> /* >> * struct to hold data for each WDT device >> @@ -79,11 +83,9 @@ static int rti_wdt_start(struct watchdog_device *wdd) >> * be petted during the open window; not too early or not too late. >> * The HW configuration options only allow for the open window size >> * to be 50% or less than that; we obviouly want to configure the open >> - * window as large as possible so we select the 50% option. To avoid >> - * any glitches, we accommodate 5% safety margin also, so we setup >> - * the min_hw_hearbeat at 55% of the timeout period. >> + * window as large as possible so we select the 50% option. >> */ >> - wdd->min_hw_heartbeat_ms = 11 * wdd->timeout * 1000 / 20; >> + wdd->min_hw_heartbeat_ms = 500 * wdd->timeout; >> >> /* Generate NMI when wdt expires */ >> writel_relaxed(RTIWWDRX_NMI, wdt->base + RTIWWDRXCTRL); >> @@ -110,7 +112,48 @@ static int rti_wdt_ping(struct watchdog_device *wdd) >> return 0; >> } >> >> -static unsigned int rti_wdt_get_timeleft(struct watchdog_device *wdd) >> +static int rti_wdt_setup_hw_hb(struct watchdog_device *wdd, u32 wsize) >> +{ >> + /* >> + * RTI only supports a windowed mode, where the watchdog can only >> + * be petted during the open window; not too early or not too late. >> + * The HW configuration options only allow for the open window size >> + * to be 50% or less than that. >> + */ >> + switch (wsize) { >> + case RTIWWDSIZE_50P: >> + /* 50% open window => 50% min heartbeat */ >> + wdd->min_hw_heartbeat_ms = 500 * heartbeat; >> + break; >> + >> + case RTIWWDSIZE_25P: >> + /* 25% open window => 75% min heartbeat */ >> + wdd->min_hw_heartbeat_ms = 750 * heartbeat; >> + break; >> + >> + case RTIWWDSIZE_12P5: >> + /* 12.5% open window => 87.5% min heartbeat */ >> + wdd->min_hw_heartbeat_ms = 875 * heartbeat; >> + break; >> + >> + case RTIWWDSIZE_6P25: >> + /* 6.5% open window => 93.5% min heartbeat */ >> + wdd->min_hw_heartbeat_ms = 935 * heartbeat; >> + break; >> + >> + case RTIWWDSIZE_3P125: >> + /* 3.125% open window => 96.9% min heartbeat */ >> + wdd->min_hw_heartbeat_ms = 969 * heartbeat; >> + break; >> + >> + default: >> + return -EINVAL; >> + } >> + >> + return 0; >> +} >> + >> +static unsigned int rti_wdt_get_timeleft_ms(struct watchdog_device *wdd) >> { >> u64 timer_counter; >> u32 val; >> @@ -123,11 +166,18 @@ static unsigned int rti_wdt_get_timeleft(struct watchdog_device *wdd) >> >> timer_counter = readl_relaxed(wdt->base + RTIDWDCNTR); >> >> + timer_counter *= 1000; >> + >> do_div(timer_counter, wdt->freq); >> >> return timer_counter; >> } >> >> +static unsigned int rti_wdt_get_timeleft(struct watchdog_device *wdd) >> +{ >> + return rti_wdt_get_timeleft_ms(wdd) / 1000; >> +} >> + >> static const struct watchdog_info rti_wdt_info = { >> .options = WDIOF_KEEPALIVEPING, >> .identity = "K3 RTI Watchdog", >> @@ -148,6 +198,7 @@ static int rti_wdt_probe(struct platform_device *pdev) >> struct watchdog_device *wdd; >> struct rti_wdt_device *wdt; >> struct clk *clk; >> + u32 last_ping = 0; >> >> wdt = devm_kzalloc(dev, sizeof(*wdt), GFP_KERNEL); >> if (!wdt) >> @@ -169,6 +220,14 @@ static int rti_wdt_probe(struct platform_device *pdev) >> return -EINVAL; >> } >> >> + /* >> + * If watchdog is running at 32k clock, it is not accurate. >> + * Adjust frequency down in this case so that we don't pet >> + * the watchdog too often. >> + */ >> + if (wdt->freq < 32768) >> + wdt->freq = wdt->freq * 9 / 10; >> + > > So this is now only a problem is the window size was set restrictively > in the BOS/ROMMON. Meaning it is still a problem. How is this better than > before ? Why not just always set the window size to something reasonable ?
Re-programming of the watchdog only takes effect at the next ping, then and only then will it adjust the window size + timeout period.
> > >> pm_runtime_enable(dev); >> ret = pm_runtime_get_sync(dev); >> if (ret) { >> @@ -185,11 +244,8 @@ static int rti_wdt_probe(struct platform_device *pdev) >> wdd->min_timeout = 1; >> wdd->max_hw_heartbeat_ms = (WDT_PRELOAD_MAX << WDT_PRELOAD_SHIFT) / >> wdt->freq * 1000; >> - wdd->timeout = DEFAULT_HEARTBEAT; >> wdd->parent = dev; >> >> - watchdog_init_timeout(wdd, heartbeat, dev); >> - >> watchdog_set_drvdata(wdd, wdt); >> watchdog_set_nowayout(wdd, 1); >> watchdog_set_restart_priority(wdd, 128); >> @@ -201,12 +257,47 @@ static int rti_wdt_probe(struct platform_device *pdev) >> goto err_iomap; >> } >> >> + if (readl(wdt->base + RTIDWDCTRL) == WDENABLE_KEY) { >> + u32 time_left_ms; >> + u64 heartbeat_ms; >> + u32 wsize; >> + >> + set_bit(WDOG_HW_RUNNING, &wdd->status); >> + time_left_ms = rti_wdt_get_timeleft_ms(wdd); >> + heartbeat_ms = readl(wdt->base + RTIDWDPRLD); >> + heartbeat_ms <<= WDT_PRELOAD_SHIFT; >> + heartbeat_ms *= 1000; >> + heartbeat_ms /= wdt->freq; > > Ah yes, the pitfalls of 64-bit divide operations.
Should I convert this to use do_div? With 64bit archs this code is targeted at it runs just fine.
> >> + if (heartbeat_ms / 1000 != heartbeat) >> + dev_warn(dev, "watchdog already running, ignoring heartbeat config!\n"); >> + >> + heartbeat = heartbeat_ms / 1000; >> + >> + wsize = readl(wdt->base + RTIWWDSIZECTRL); >> + ret = rti_wdt_setup_hw_hb(wdd, wsize); >> + if (ret) { >> + dev_err(dev, "bad window size.\n"); >> + goto err_iomap; >> + } >> + >> + last_ping = heartbeat_ms - time_left_ms; >> + if (time_left_ms > heartbeat_ms) { >> + dev_warn(dev, "time_left > heartbeat? Assuming last ping just before now.\n"); >> + last_ping = 0; >> + } > > All that complexity makes me wonder if it wouldn't be better to just reprogram > the watchdog if it is already running. Any reason for not doing that ?
Well, you can re-program it but... It does not take effect until next window starts, so basically we need to take care of the currently running window anyways after which re-programming it doesn't make much sense anymore. And handling the switch from one setup to next would add extra complexity.
-Tero
> >> + } >> + >> + watchdog_init_timeout(wdd, heartbeat, dev); >> + >> ret = watchdog_register_device(wdd); >> if (ret) { >> dev_err(dev, "cannot register watchdog device\n"); >> goto err_iomap; >> } >> >> + if (last_ping) >> + watchdog_set_last_hw_keepalive(wdd, last_ping); >> + >> return 0; >> >> err_iomap: >> >
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