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

Hald, Ulrik Bech
2009-06-09T19:28:13Z

> -----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().

>
> > 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.

Do you mean just using:
snprintf(wdt_name, sizeof(wdt_name), "watchdog%d", pdev->id);
wdev->omap_wdt_miscdev.name = wdt_name;

...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