On Wed, Sep 24, 2014 at 08:58:54AM -0700, Guenter Roeck wrote:
> On Tue, Sep 23, 2014 at 06:04:36PM -0500, Josh Cartwright wrote:
> > Add a driver for the watchdog timer block found in the Krait Processor
> > Subsystem (KPSS) on the MSM8960, APQ8064, and IPQ8064.
> >
> > Signed-off-by: Josh Cartwright <joshc@xxxxxxxxxxxxxx>
>
> Hi Josh,
>
> looks much better. Couple of comments inline.
Thanks for another review!
[..]
> > +++ b/drivers/watchdog/Kconfig
> > @@ -443,6 +443,19 @@ config TEGRA_WATCHDOG
> > To compile this driver as a module, choose M here: the
> > module will be called tegra_wdt.
> >
> > +config QCOM_WDT
> > + tristate "QCOM watchdog"
> > + depends on HAS_IOMEM
> > + depends on ARCH_QCOM
> > + select WATCHDOG_CORE
> > + help
> > + Say Y here to include Watchdog timer support for the watchdog found
> > + on QCOM chipsets. Currently supported targets are the MSM8960,
> > + APQ8064, and IPQ8064.
> > +
> > + To compile this driver as a module, choose M here: the
> > + module will be called qcom_wdt.
> > +
> > # AVR32 Architecture
[..]
> > +static int qcom_wdt_probe(struct platform_device *pdev)
> > +{
> > + struct qcom_wdt *wdt;
> > + struct resource *res;
> > + unsigned long freq;
> > + int ret;
> > +
> > + wdt = devm_kzalloc(&pdev->dev, sizeof(*wdt), GFP_KERNEL);
> > + if (!wdt)
> > + return -ENOMEM;
> > +
> > + res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
> > + wdt->base = devm_ioremap_resource(&pdev->dev, res);
> > + if (IS_ERR(wdt->base))
> > + return PTR_ERR(wdt->base);
> > +
> > + wdt->clk = devm_clk_get(&pdev->dev, NULL);
> > + if (IS_ERR(wdt->clk))
> > + return PTR_ERR(wdt->clk);
> > +
> > + ret = clk_prepare_enable(wdt->clk);
> > + if (ret) {
> > + dev_err(&pdev->dev, "failed to setup clock\n");
> > + return ret;
> > + }
> > +
> > + /*
> > + * We use the clock rate to calculate the max timeout, so ensure it's
> > + * not zero to avoid a divide-by-zero exception.
> > + */
> > + freq = clk_get_rate(wdt->clk);
> > + if (freq == 0) {
> > + dev_err(&pdev->dev, "invalid clock rate\n");
> > + return -EINVAL;
> > + }
>
> This will need clk_disable_unprepare().
Yep. Nice catch. Will fix.
> Since you are reading the frequency here, it might make sense to store it
> in struct qcom_wdt so you don't have to call clk_get_rate() again in the
> start function.
Yeah, it doesn't save much, but I'll go ahead and add it.
> > + wdt->wdd.dev = &pdev->dev;
> > + wdt->wdd.info = &qcom_wdt_info;
> > + wdt->wdd.ops = &qcom_wdt_ops;
> > + wdt->wdd.min_timeout = 1;
> > + wdt->wdd.max_timeout = 0x10000000U / freq;
>
> What if the frequency turns out to be larger than 8947848 Hz ?
> Then your maximum timeout is below the default timeout.
> And if the frequency is larger than 268435456 Hz, the maximum
> timeout would be 0.
Yes, I should be doing more sanity checking. I'll do so.
> > + /*
> > + * If 'timeout-sec' unspecified in devicetree, assume a 30 second
> > + * default.
> > + */
> > + if (watchdog_init_timeout(&wdt->wdd, 0, &pdev->dev))
> > + wdt->wdd.timeout = 30;
>
> You can just initialize timeout above with 30 seconds. Saves you the if
> statement here.
Great. Thanks.
> > + ret = watchdog_register_device(&wdt->wdd);
> > + if (ret) {
> > + dev_err(&pdev->dev, "failed to register watchdog\n");
>
> This will need a clk_disable_unprepare().
>
> Given that this is needed twice, you might want to consider using
> error exit code below, as suggested in CodingStyle.
Indeed. Will do.
Thanks again,
Josh
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