Re: [RFC PATCH v3] watchdog: sp805: Add clock-frequency property

[Guenter Roeck]

On 07/11/2018 06:22 AM, Srinath Mannam wrote:
> Hi Guenter,
>
> Thank you very much for all the help with your feedback and review
> comments to complete the changes very fast.
>
> About the documentation..
> I have gone through few similar patches available in the kernel are
> listed in the mail of previous version.
> No documentation available in Linux for the properties used in those
> patches also.

" No documentation available _in Linux_"

Emphasis mine. Yes, I noticed this as well. I was asking for a reference
to documentation _outside_ Linux. Sorry for not being more specific.

Guenter

> For example,
> 1: "src-clock-hz" property added in the part of ACPI support with the
> below patch.
> Patch details: commit 515da746983bc6382e380ba8b1ce9345a9550ffe
> Author: Naveen Kaje <nkaje@xxxxxxxxxxxxxx>
> Date:   Tue Oct 11 10:27:56 2016 -0600
>
>      i2c: qup: add ACPI support
> 2: "amd,dma-freq" property added in the part of ACPI support with the
> below patch
> commit 82a19035d000c8b4fd7d6f61b614f63dec75d389
> Author: Lendacky, Thomas <Thomas.Lendacky@xxxxxxx>
> Date:   Fri Jan 16 12:47:16 2015 -0600
>
>      amd-xgbe: Add ACPI support
>
> Regards,
> Srinath.
>
>
>
>
> On Wed, Jul 11, 2018 at 3:05 AM, Guenter Roeck <linux@xxxxxxxxxxxx> wrote:
> > On Tue, Jul 10, 2018 at 02:14:39PM +0530, Srinath Mannam wrote:
> > > When using ACPI node, binding clock devices are
> > > not available as device tree, So clock-frequency
> > > property given in _DSD object of ACPI device is
> > > used to calculate Watchdog rate.
> > >
> > > Signed-off-by: Srinath Mannam <srinath.mannam@xxxxxxxxxxxx>
> >
> > I am ok with the patch itself. All that is missing now is a
> > reference to the _DSD property documentation. Is that published
> > somewhere or is it all wild-wild-west ?
> >
> > Thanks,
> > Guenter
> >
> > > ---
> > >   drivers/watchdog/sp805_wdt.c | 35 +++++++++++++++++++++++++----------
> > >   1 file changed, 25 insertions(+), 10 deletions(-)
> > >
> > > diff --git a/drivers/watchdog/sp805_wdt.c b/drivers/watchdog/sp805_wdt.c
> > > index 9849db0..a896b1c 100644
> > > --- a/drivers/watchdog/sp805_wdt.c
> > > +++ b/drivers/watchdog/sp805_wdt.c
> > > @@ -11,6 +11,7 @@
> > >    * warranty of any kind, whether express or implied.
> > >    */
> > >
> > > +#include <linux/acpi.h>
> > >   #include <linux/device.h>
> > >   #include <linux/resource.h>
> > >   #include <linux/amba/bus.h>
> > > @@ -22,6 +23,7 @@
> > >   #include <linux/math64.h>
> > >   #include <linux/module.h>
> > >   #include <linux/moduleparam.h>
> > > +#include <linux/of.h>
> > >   #include <linux/pm.h>
> > >   #include <linux/slab.h>
> > >   #include <linux/spinlock.h>
> > > @@ -65,6 +67,7 @@ struct sp805_wdt {
> > >        spinlock_t                      lock;
> > >        void __iomem                    *base;
> > >        struct clk                      *clk;
> > > +     u64                             rate;
> > >        struct amba_device              *adev;
> > >        unsigned int                    load_val;
> > >   };
> > > @@ -80,7 +83,7 @@ static int wdt_setload(struct watchdog_device *wdd, unsigned int timeout)
> > >        struct sp805_wdt *wdt = watchdog_get_drvdata(wdd);
> > >        u64 load, rate;
> > >
> > > -     rate = clk_get_rate(wdt->clk);
> > > +     rate = wdt->rate;
> > >
> > >        /*
> > >         * sp805 runs counter with given value twice, after the end of first
> > > @@ -106,9 +109,7 @@ static int wdt_setload(struct watchdog_device *wdd, unsigned int timeout)
> > >   static unsigned int wdt_timeleft(struct watchdog_device *wdd)
> > >   {
> > >        struct sp805_wdt *wdt = watchdog_get_drvdata(wdd);
> > > -     u64 load, rate;
> > > -
> > > -     rate = clk_get_rate(wdt->clk);
> > > +     u64 load;
> > >
> > >        spin_lock(&wdt->lock);
> > >        load = readl_relaxed(wdt->base + WDTVALUE);
> > > @@ -118,7 +119,7 @@ static unsigned int wdt_timeleft(struct watchdog_device *wdd)
> > >                load += wdt->load_val + 1;
> > >        spin_unlock(&wdt->lock);
> > >
> > > -     return div_u64(load, rate);
> > > +     return div_u64(load, wdt->rate);
> > >   }
> > >
> > >   static int
> > > @@ -228,11 +229,25 @@ sp805_wdt_probe(struct amba_device *adev, const struct amba_id *id)
> > >        if (IS_ERR(wdt->base))
> > >                return PTR_ERR(wdt->base);
> > >
> > > -     wdt->clk = devm_clk_get(&adev->dev, NULL);
> > > -     if (IS_ERR(wdt->clk)) {
> > > -             dev_warn(&adev->dev, "Clock not found\n");
> > > -             ret = PTR_ERR(wdt->clk);
> > > -             goto err;
> > > +     if (adev->dev.of_node) {
> > > +             wdt->clk = devm_clk_get(&adev->dev, NULL);
> > > +             if (IS_ERR(wdt->clk)) {
> > > +                     dev_err(&adev->dev, "Clock not found\n");
> > > +                     return PTR_ERR(wdt->clk);
> > > +             }
> > > +             wdt->rate = clk_get_rate(wdt->clk);
> > > +     } else if (has_acpi_companion(&adev->dev)) {
> > > +             /*
> > > +              * When Driver probe with ACPI device, clock devices
> > > +              * are not available, so watchdog rate get from
> > > +              * clock-frequency property given in _DSD object.
> > > +              */
> > > +             device_property_read_u64(&adev->dev, "clock-frequency",
> > > +                                      &wdt->rate);
> > > +             if (!wdt->rate) {
> > > +                     dev_err(&adev->dev, "no clock-frequency property\n");
> > > +                     return -ENODEV;
> > > +             }
> > >        }
> > >
> > >        wdt->adev = adev;
> > > --
> > > 2.7.4
> --
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