RE: [PATCH 2/3] OMAP3:WDT:Enable support for IVA and SECURE

Hald, Ulrik Bech
2009-06-15T16:19:20Z

> -----Original Message-----
> From: Kevin Hilman [mailto:khilman@deeprootsystems.com]
> Sent: Tuesday, June 09, 2009 4:10 PM
> To: Hald, Ulrik Bech
> Cc: linux-omap@vger.kernel.org
> Subject: Re: [PATCH 2/3] OMAP3:WDT:Enable support for IVA and SECURE
>
> "Hald, Ulrik Bech" <ubh@ti.com> writes:
>
> >> -----Original Message-----
> >> From: Kevin Hilman [mailto:khilman@deeprootsystems.com]
> >> Sent: Tuesday, June 09, 2009 9:47 AM
> >> To: Hald, Ulrik Bech
> >> Cc: linux-omap@vger.kernel.org
> >> Subject: Re: [PATCH 2/3] OMAP3:WDT:Enable support for IVA and SECURE
> >>
> >> Ulrik Bech Hald <ubh@ti.com> writes:
> >>
> >> > This patch enables the IVA and SECURE WDTs in the omap_wdt
> >> > driver for omap34xx family. SECURE will be available as
> /dev/watchdog1
> >> > HS/EMU devices and IVA will be available as /dev/watchdog3.
> >> > MPU will be available as /dev/watchdog2
> >> > For omap versions earlier than 34xx only MPU watchdog is present and
> >> > will be available as /dev/watchdog for backwards compatibility.
> >> >
> >> > Signed-off-by: Ulrik Bech Hald <ubh@ti.com>
> >> > ---
> >> > drivers/watchdog/omap_wdt.c | 42
> +++++++++++++++++++++++++++++++++++-
> >> ------
> >> > 1 files changed, 35 insertions(+), 7 deletions(-)
> >> > mode change 100644 => 100755 drivers/watchdog/omap_wdt.c
> >> >
> >> > diff --git a/drivers/watchdog/omap_wdt.c
> b/drivers/watchdog/omap_wdt.c
> >>
> >> [...]
> >>
> >> > static int omap_wdt_open(struct inode *inode, struct file *file)
> >> > {
> >> > - struct omap_wdt_dev *wdev =
> platform_get_drvdata(omap_wdt_dev);
> >> > - void __iomem *base = wdev->base;
> >> > + struct omap_wdt_dev *wdev;
> >> > + void __iomem *base;
> >> > +
> >> > + /* by default MPU wdt is present across omap family */
> >> > + wdev = platform_get_drvdata(omap_wdt_dev[1]);
> >> > +
> >> > + /* if multiple wdts, find match between device node and wdt
> device
> >> */
> >> > + if (cpu_is_omap34xx()) {
> >> > + int i;
> >> > + for (i = 0; i < NUM_WDTS; i++) {
> >> > + if (omap_wdt_dev[i]) {
> >> > + wdev =
> platform_get_drvdata(omap_wdt_dev[i]);
> >> > + if (iminor(inode)
> >> > + == wdev->omap_wdt_miscdev.minor)
> >> > + break;
> >> > + }
> >> > + }
> >> > + }
> >> > +
> >> > + base = wdev->base;
> >>
> >> Hmm, this does not look right to me. Any use of cpu_is_* in driver
> >> code usually indicates that something is not quite right. This same
> >> watchdog IP is used in some DaVinci family processors and needs to be
> >> reused there.
> >>
> >> I didn't do the miscdev research, but can't you get the pdev from the
> >> miscdev.parent, and from there get the right wdev pointer from the
> >> pdev.drvdata.
> >>
> >> Otherwise, drop the cpu_is_* and just do inode checking all the time.
> >> The way you've done it looks error prone to me.
> >
> > I can't really see a to way pair the driver and device other than
> > doing inode/minor number checking , so I'll just go for the inode
> > checking without any dependency on cpu_is_xxx().
>
> OK.
>
> >>
> >> > if (test_and_set_bit(1, (unsigned long *)&(wdev-
> >omap_wdt_users)))
> >> > return -EBUSY;
> >> > @@ -263,6 +283,7 @@ static int __devinit omap_wdt_probe(struct
> >> platform_device *pdev)
> >> > struct resource *res, *mem;
> >> > struct omap_wdt_dev *wdev;
> >> > int ret;
> >> > + static char wdt_name[32];
> >> >
> >> > /* reserve static register mappings */
> >> > res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
> >> > @@ -271,7 +292,7 @@ static int __devinit omap_wdt_probe(struct
> >> platform_device *pdev)
> >> > goto err_get_resource;
> >> > }
> >> >
> >> > - if (omap_wdt_dev) {
> >> > + if (omap_wdt_dev[pdev->id-1]) {
> >> > ret = -EBUSY;
> >> > goto err_busy;
> >> > }
> >> > @@ -318,8 +339,14 @@ static int __devinit omap_wdt_probe(struct
> >> platform_device *pdev)
> >> >
> >> > wdev->omap_wdt_miscdev.parent = &pdev->dev;
> >> > wdev->omap_wdt_miscdev.minor = WATCHDOG_MINOR;
> >> > - wdev->omap_wdt_miscdev.name = "watchdog";
> >> > wdev->omap_wdt_miscdev.fops = &omap_wdt_fops;
> >> > + wdev->omap_wdt_miscdev.name = "watchdog";
> >> > + if (cpu_is_omap34xx()) {
> >> > + snprintf(wdt_name, sizeof(wdt_name), "watchdog%d", pdev-
> >id);
> >> > + wdev->omap_wdt_miscdev.name = wdt_name;
> >> > + if (pdev->id != 2)
> >> > + wdev->omap_wdt_miscdev.minor = MISC_DYNAMIC_MINOR;
> >> > + }
> >>
> >> Again, red flag: cpu_is_*
> >>
> >> It might be more consistent to use pdev->dev->name which is already of
> >> the form "watchdog.%d".
> >
> > Not sure I follow. I don't see a "name" field in struct device, only
> init_name.
>
> Sorry, I meant dev->bus_id. Look at dev_set_name() which creates
> a bus_id of the form ("%s.%d", pdev->name, pdev->id)

As far as I can see, dev->bus_id has been removed from the device struct as per 1fa5ae857bb14f6046205171d98506d8112dd74e.
Furthermore, the pdev->name is "omap_wdt", which should be presented as "watchdog" in wdev->omap_wdt_miscdev.name anyway, so I think I'll just go with the sprintf() approach below, keeping your wdt_name comments in mind.

/Ulrik

>
> > Do you mean just using:
> > snprintf(wdt_name, sizeof(wdt_name), "watchdog%d", pdev->id);
> > wdev->omap_wdt_miscdev.name = wdt_name;
>
> Using pdev->id is ok, but that's what dev_set_name() does.
>
> Note that if you decide to go this route, note that wdt_name doesn't
> need to be static. The driver core will copy the name field the
> misc_device. If it wasn't copying, you'd have all of the miscdev.name
> fields ending up being the same thing since they are all assigned the
> same pointer.
>
> Kevin
>
> > ...for all the WDT devices, despite how many are present?
> >
> >>
> >> Any reason not to use MISC_DYNAMIC_MINOR for all of them?
> >
> > No particular reason other than I thought that retaining the use of
> WATCHDOG_MINOR for the MPU WDT case would be appropriate. But it does make
> the code cleaner to use only MISC_DYNAMIC_MINOR. I'll change it.
> >
> > Thanks for reviewing!
> >
> >>
> >> Kevin