On Wed, May 23, 2018 at 06:15:14PM +0100, Robin Murphy wrote:

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

quoted

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;

== has higher precendence than bitwise &, so this will need ( ),
but otherwise I agree.

which is still -3 lines vs. the original.

quoted

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 ;)

Yes, that would be confusing.

Robin.