On 23/05/18 17:29, Ray Jui wrote:

Hi Robin,

On 5/23/2018 4:48 AM, Robin Murphy wrote:

quoted

On 23/05/18 08:52, Scott Branden wrote:

quoted

On 18-05-22 04:24 PM, Ray Jui wrote:

quoted

Hi Guenter,

On 5/22/2018 1:54 PM, Guenter Roeck wrote:

quoted

On Tue, May 22, 2018 at 11:47:18AM -0700, Ray Jui wrote:

quoted

If the watchdog hardware is already enabled during the boot process,
when the Linux watchdog driver loads, it should reset the watchdog 
and
tell the watchdog framework. As a result, ping can be generated from
the watchdog framework, until the userspace watchdog daemon takes 
over
control

Signed-off-by: Ray Jui <redacted>
Reviewed-by: Vladimir Olovyannikov 
[off-list ref]
Reviewed-by: Scott Branden <scott.branden@broadcom.com>
---
  drivers/watchdog/sp805_wdt.c | 22 ++++++++++++++++++++++
  1 file changed, 22 insertions(+)

diff --git a/drivers/watchdog/sp805_wdt.c 

b/drivers/watchdog/sp805_wdt.c
index 1484609..408ffbe 100644

--- a/drivers/watchdog/sp805_wdt.c
+++ b/drivers/watchdog/sp805_wdt.c

@@ -42,6 +42,7 @@

      /* control register masks */
      #define    INT_ENABLE    (1 << 0)
      #define    RESET_ENABLE    (1 << 1)
+    #define    ENABLE_MASK    (INT_ENABLE | RESET_ENABLE)
  #define WDTINTCLR        0x00C
  #define WDTRIS            0x010
  #define WDTMIS            0x014

@@ -74,6 +75,18 @@ module_param(nowayout, bool, 0);

  MODULE_PARM_DESC(nowayout,
          "Set to 1 to keep watchdog running after device release");
  +/* returns true if wdt is running; otherwise returns false */
+static bool wdt_is_running(struct watchdog_device *wdd)
+{
+    struct sp805_wdt *wdt = watchdog_get_drvdata(wdd);
+
+    if ((readl_relaxed(wdt->base + WDTCONTROL) & ENABLE_MASK) ==
+        ENABLE_MASK)
+        return true;
+    else
+        return false;

    return !!(readl_relaxed(wdt->base + WDTCONTROL) & ENABLE_MASK));

Note ENABLE_MASK contains two bits (INT_ENABLE and RESET_ENABLE); 
therefore, a simple !!(expression) would not work? That is, the 
masked result needs to be compared against the mask again to ensure 
both bits are set, right?

Ray - your original code looks correct to me.  Easier to read and 
less prone to errors as shown in the attempted translation to a 
single statement.

     if (<boolean condition>)
         return true;
     else
         return false;

still looks really dumb, though, and IMO is actually harder to read 
than just "return <boolean condition>;" because it forces you to stop 
and double-check that the logic is, in fact, only doing the obvious 
thing.

If you can propose a way to modify my original code above to make it 
more readable, I'm fine to make the change.

Well,

	return readl_relaxed(wdt->base + WDTCONTROL) & ENABLE_MASK == ENABLE_MASK;

would probably be reasonable to anyone other than the 80-column zealots, 
but removing the silly boolean-to-boolean translation idiom really only 
emphasises the fact that it's fundamentally a big complex statement; for 
maximum clarity I'd be inclined to separate the two logical operations 
(read and comparison), e.g.:

	u32 wdtcontrol = readl_relaxed(wdt->base + WDTCONTROL);

	return wdtcontrol & ENABLE_MASK == ENABLE_MASK;

which is still -3 lines vs. the original.

As I mentioned, I don't think the following change proposed by Guenter 
will work due to the reason I pointed out:

return !!(readl_relaxed(wdt->base + WDTCONTROL) & ENABLE_MASK));

FWIW, getting the desired result should only need one logical not 
swapping for a bitwise one there:

	return !(~readl_relaxed(wdt->base + WDTCONTROL) & ENABLE_MASK);

but that's well into "too clever for its own good" territory ;)

Robin.