| Message ID | 1456851608-3374907-2-git-send-email-arnd@arndb.de (mailing list archive) |
|---|---|
| State | Not Applicable |
| Headers | show |
Hi Arnd, On Tue, Mar 1, 2016 at 5:59 PM, Arnd Bergmann <arnd@arndb.de> wrote: > There are four architectures using this driver, but since we can > build it with COMPILE_TEST, we should try dealing with the absence > of the asm/rtc.h header file, to avoid getting a build error: > > drivers/rtc/rtc-generic.c:12:21: fatal error: asm/rtc.h: No such file or directory > > This creates an alternative use of the driver, allowing architectures > to pass a set of rtc_class_ops in platform data. We can convert the > four architectures to use this and then remove the original > code. > > Signed-off-by: Arnd Bergmann <arnd@arndb.de> > --- > drivers/rtc/rtc-generic.c | 12 +++++++++++- > 1 file changed, 11 insertions(+), 1 deletion(-) > > diff --git a/drivers/rtc/rtc-generic.c b/drivers/rtc/rtc-generic.c > index e782ebd719b2..d726c6aa96a8 100644 > --- a/drivers/rtc/rtc-generic.c > +++ b/drivers/rtc/rtc-generic.c > @@ -9,6 +9,8 @@ > #include <linux/platform_device.h> > #include <linux/rtc.h> > > +#if defined(CONFIG_M68K) || defined(CONFIG_PARISC) || \ > + defined(CONFIG_PPC) || defined(CONFIG_SUPERH32) > #include <asm/rtc.h> > > static int generic_get_time(struct device *dev, struct rtc_time *tm) > @@ -33,13 +35,21 @@ static const struct rtc_class_ops generic_rtc_ops = { > .read_time = generic_get_time, > .set_time = generic_set_time, > }; > +#else > +#define generic_rtc_ops *(struct rtc_class_ops*)NULL > +#endif > > static int __init generic_rtc_probe(struct platform_device *dev) > { > struct rtc_device *rtc; > + const struct rtc_class_ops *ops; > + > + ops = dev_get_platdata(&dev->dev); > + if (!ops) > + ops = &generic_rtc_ops; I hope no compiler version treats "&*(struct rtc_class_ops*)NULL" as undefined behavior? > > rtc = devm_rtc_device_register(&dev->dev, "rtc-generic", > - &generic_rtc_ops, THIS_MODULE); > + ops, THIS_MODULE); > if (IS_ERR(rtc)) > return PTR_ERR(rtc); Gr{oetje,eeting}s, Geert -- Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org In personal conversations with technical people, I call myself a hacker. But when I'm talking to journalists I just say "programmer" or something like that. -- Linus Torvalds -- To unsubscribe from this list: send the line "unsubscribe linux-parisc" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On Wednesday 02 March 2016 09:57:27 Geert Uytterhoeven wrote: > > @@ -33,13 +35,21 @@ static const struct rtc_class_ops generic_rtc_ops = { > > .read_time = generic_get_time, > > .set_time = generic_set_time, > > }; > > +#else > > +#define generic_rtc_ops *(struct rtc_class_ops*)NULL > > +#endif > > > > static int __init generic_rtc_probe(struct platform_device *dev) > > { > > struct rtc_device *rtc; > > + const struct rtc_class_ops *ops; > > + > > + ops = dev_get_platdata(&dev->dev); > > + if (!ops) > > + ops = &generic_rtc_ops; > > I hope no compiler version treats "&*(struct rtc_class_ops*)NULL" as > undefined behavior? It's a bit odd, but I think it's syntactically correct C, and not much too different from #define offsetof(TYPE, MEMBER) ((size_t)&((TYPE *)0)->MEMBER) is it? My last patch gets rid of it again. Arnd -- To unsubscribe from this list: send the line "unsubscribe linux-parisc" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
Geert Uytterhoeven <geert@linux-m68k.org> writes: >> +#else >> +#define generic_rtc_ops *(struct rtc_class_ops*)NULL >> +#endif >> >> static int __init generic_rtc_probe(struct platform_device *dev) >> { >> struct rtc_device *rtc; >> + const struct rtc_class_ops *ops; >> + >> + ops = dev_get_platdata(&dev->dev); >> + if (!ops) >> + ops = &generic_rtc_ops; > > I hope no compiler version treats "&*(struct rtc_class_ops*)NULL" as > undefined behavior? Yes, that is guaranteed, the operations cancel each other (6.5.3.2#3: If the operand is the result of a unary * operator, neither that operator nor the & operator is evaluated and the result is as if both were omitted). Andreas.
On Wed, Mar 2, 2016 at 10:28 AM, Andreas Schwab <schwab@linux-m68k.org> wrote: > Geert Uytterhoeven <geert@linux-m68k.org> writes: > >>> +#else >>> +#define generic_rtc_ops *(struct rtc_class_ops*)NULL >>> +#endif >>> >>> static int __init generic_rtc_probe(struct platform_device *dev) >>> { >>> struct rtc_device *rtc; >>> + const struct rtc_class_ops *ops; >>> + >>> + ops = dev_get_platdata(&dev->dev); >>> + if (!ops) >>> + ops = &generic_rtc_ops; >> >> I hope no compiler version treats "&*(struct rtc_class_ops*)NULL" as >> undefined behavior? > > Yes, that is guaranteed, the operations cancel each other (6.5.3.2#3: If > the operand is the result of a unary * operator, neither that operator > nor the & operator is evaluated and the result is as if both were > omitted). Thanks for confirming. Gr{oetje,eeting}s, Geert -- Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org In personal conversations with technical people, I call myself a hacker. But when I'm talking to journalists I just say "programmer" or something like that. -- Linus Torvalds -- To unsubscribe from this list: send the line "unsubscribe linux-parisc" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
diff --git a/drivers/rtc/rtc-generic.c b/drivers/rtc/rtc-generic.c index e782ebd719b2..d726c6aa96a8 100644 --- a/drivers/rtc/rtc-generic.c +++ b/drivers/rtc/rtc-generic.c @@ -9,6 +9,8 @@ #include <linux/platform_device.h> #include <linux/rtc.h> +#if defined(CONFIG_M68K) || defined(CONFIG_PARISC) || \ + defined(CONFIG_PPC) || defined(CONFIG_SUPERH32) #include <asm/rtc.h> static int generic_get_time(struct device *dev, struct rtc_time *tm) @@ -33,13 +35,21 @@ static const struct rtc_class_ops generic_rtc_ops = { .read_time = generic_get_time, .set_time = generic_set_time, }; +#else +#define generic_rtc_ops *(struct rtc_class_ops*)NULL +#endif static int __init generic_rtc_probe(struct platform_device *dev) { struct rtc_device *rtc; + const struct rtc_class_ops *ops; + + ops = dev_get_platdata(&dev->dev); + if (!ops) + ops = &generic_rtc_ops; rtc = devm_rtc_device_register(&dev->dev, "rtc-generic", - &generic_rtc_ops, THIS_MODULE); + ops, THIS_MODULE); if (IS_ERR(rtc)) return PTR_ERR(rtc);
There are four architectures using this driver, but since we can build it with COMPILE_TEST, we should try dealing with the absence of the asm/rtc.h header file, to avoid getting a build error: drivers/rtc/rtc-generic.c:12:21: fatal error: asm/rtc.h: No such file or directory This creates an alternative use of the driver, allowing architectures to pass a set of rtc_class_ops in platform data. We can convert the four architectures to use this and then remove the original code. Signed-off-by: Arnd Bergmann <arnd@arndb.de> --- drivers/rtc/rtc-generic.c | 12 +++++++++++- 1 file changed, 11 insertions(+), 1 deletion(-)