On Fri, 29 Oct 2021 at 11:18, Krzysztof Kozlowski <krzysztof.kozlowski@xxxxxxxxxxxxx> wrote: > > On 28/10/2021 20:35, Sam Protsenko wrote: > > Some Exynos chips (like Exynos850) have dedicated source clock. That > > clock is provided from device tree as "watchdog_src" clock. In such > > case, "watchdog" clock is just a peripheral clock used for register > > interface. If "watchdog_src" is present, use its rate instead of > > "watchdog" for all timer related calculations. > > Please explain what is this source clock and remove the reference to > devicetree. Instead describe rather real HW. It's confusing now to have > one clock called watchdog and one watchdog source. > > The source clock is the actual clock driving watchdog and it's counter, > right? Then let's document it and rename the variables to match reality > - one is pclk (or apb?) and second is counter or source? > Done, will be present in v2. > > > > Signed-off-by: Sam Protsenko <semen.protsenko@xxxxxxxxxx> > > --- > > drivers/watchdog/s3c2410_wdt.c | 33 +++++++++++++++++++++++++++------ > > 1 file changed, 27 insertions(+), 6 deletions(-) > > > > diff --git a/drivers/watchdog/s3c2410_wdt.c b/drivers/watchdog/s3c2410_wdt.c > > index a5ef7171a90e..bfc5872ca497 100644 > > --- a/drivers/watchdog/s3c2410_wdt.c > > +++ b/drivers/watchdog/s3c2410_wdt.c > > @@ -126,6 +126,8 @@ struct s3c2410_wdt_variant { > > struct s3c2410_wdt { > > struct device *dev; > > struct clk *clock; > > + struct clk *clock_src; > > + unsigned long freq_src; > > void __iomem *reg_base; > > unsigned int count; > > spinlock_t lock; > > @@ -213,10 +215,8 @@ MODULE_DEVICE_TABLE(platform, s3c2410_wdt_ids); > > > > /* functions */ > > > > -static inline unsigned int s3c2410wdt_max_timeout(struct clk *clock) > > +static inline unsigned int s3c2410wdt_max_timeout(unsigned long freq) > > { > > - unsigned long freq = clk_get_rate(clock); > > - > > return S3C2410_WTCNT_MAXCNT / (freq / (S3C2410_WTCON_PRESCALE_MAX + 1) > > / S3C2410_WTCON_MAXDIV); > > } > > @@ -364,7 +364,7 @@ static int s3c2410wdt_set_heartbeat(struct watchdog_device *wdd, > > unsigned int timeout) > > { > > struct s3c2410_wdt *wdt = watchdog_get_drvdata(wdd); > > - unsigned long freq = clk_get_rate(wdt->clock); > > + unsigned long freq = wdt->freq_src; > > This does not look good. You are using fixed frequency (from probe). > Ok, will avoid caching this value in v2. > > unsigned int count; > > unsigned int divisor = 1; > > unsigned long wtcon; > > @@ -627,13 +627,27 @@ static int s3c2410wdt_probe(struct platform_device *pdev) > > return ret; > > } > > > > + /* "watchdog_src" clock is optional; if it's not present -- just skip */ > > + wdt->clock_src = devm_clk_get(dev, "watchdog_src"); > > + if (!IS_ERR(wdt->clock_src)) { > > + ret = clk_prepare_enable(wdt->clock_src); > > + if (ret < 0) { > > + dev_err(dev, "failed to enable source clock\n"); > > + ret = PTR_ERR(wdt->clock_src); > > + goto err_clk; > > + } > > + wdt->freq_src = clk_get_rate(wdt->clock_src); > > + } else { > > + wdt->freq_src = clk_get_rate(wdt->clock); > > + } > > + > > wdt->wdt_device.min_timeout = 1; > > - wdt->wdt_device.max_timeout = s3c2410wdt_max_timeout(wdt->clock); > > + wdt->wdt_device.max_timeout = s3c2410wdt_max_timeout(wdt->freq_src); > > > > ret = s3c2410wdt_cpufreq_register(wdt); > > if (ret < 0) { > > dev_err(dev, "failed to register cpufreq\n"); > > - goto err_clk; > > + goto err_clk_src; > > } > > > > watchdog_set_drvdata(&wdt->wdt_device, wdt); > > @@ -707,6 +721,10 @@ static int s3c2410wdt_probe(struct platform_device *pdev) > > err_cpufreq: > > s3c2410wdt_cpufreq_deregister(wdt); > > > > + err_clk_src: > > + if (!IS_ERR(wdt->clock_src)) > > + clk_disable_unprepare(wdt->clock_src); > > No. Errors in getting source clock should not be ignored, so you should > never store here ERR. You could store NULL. If() is anyway not needed in > both cases. > > You can simplify all this and take pclk twice if src clock is missing. > Or assign src=pclk... > Hmm, I don't want to take the same clock twice. It'll increase its refcount twice, which might be confusing in some cases. I guess I'll rework it to be like this in v2: - add "has_src_clk" bool field to struct wdt - if "watchdog_src" is provided: set has_src_clk "true" - if "watchdog_src" is not provided: set has_src_clk "false" (default BSS val) and assign src=pclk - only enable/disable src clock when has_src_clk is "true" That simplifies clock using, fixes stored pointer value, and avoids taking the clock twice, all at the same time. Hope that way is fine with you. > > + > > err_clk: > > clk_disable_unprepare(wdt->clock); > > > > @@ -727,6 +745,9 @@ static int s3c2410wdt_remove(struct platform_device *dev) > > > > s3c2410wdt_cpufreq_deregister(wdt); > > > > + if (!IS_ERR(wdt->clock_src)) > > + clk_disable_unprepare(wdt->clock_src); > > + > > clk_disable_unprepare(wdt->clock); > > > > return 0; > > > > > Best regards, > Krzysztof