Messages in this thread | | | Subject | Re: [PATCH v2 1/3] kernel: Provide a __pow10() function | From | Guenter Roeck <> | Date | Tue, 7 May 2019 16:21:02 -0700 |
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On 5/7/19 2:49 PM, Florian Fainelli wrote: > On 5/7/19 2:06 PM, Guenter Roeck wrote: >> On Tue, May 07, 2019 at 12:35:02PM -0700, Florian Fainelli wrote: >>> Provide a simple macro that can return the value of 10 raised to a >>> positive integer. We are going to use this in order to scale units from >>> firmware to HWMON. >>> >>> Signed-off-by: Florian Fainelli <f.fainelli@gmail.com> >>> --- >>> include/linux/kernel.h | 11 +++++++++++ >>> 1 file changed, 11 insertions(+) >>> >>> diff --git a/include/linux/kernel.h b/include/linux/kernel.h >>> index 2d14e21c16c0..62fc8bd84bc9 100644 >>> --- a/include/linux/kernel.h >>> +++ b/include/linux/kernel.h >>> @@ -294,6 +294,17 @@ static inline u32 reciprocal_scale(u32 val, u32 ep_ro) >>> return (u32)(((u64) val * ep_ro) >> 32); >>> } >>> >>> +/* Return in f the value of 10 raise to the power x */ >>> +#define __pow10(x, f)( \ >>> +{ \ >>> + typeof(x) __x = abs(x); \ >>> + f = 1; \ >>> + while (__x--) \ >>> + f *= 10; \ >>> + f; \ >>> +} \ >>> +) >> >> Kind of unusual. I would have expected to use this like >> f = __pow10(x); >> ie without having to provide f as parameter. That would be much less >> confusing. I assume this is to make the result type independent, but >> I am not sure if that is worth the trouble. > > Correct, that was the intent here. > >> >> Are there users outside the hwmon code ? If not, it might be simpler >> to keep it there for now. > > There appears to be a few outside actually: > > drivers/acpi/sbs.c::battery_scale > drivers/iio/common/hid-sensors/hid-sensor-attributes.c::pow_10 > > There could be others but those two came out as obvious candidates. > > Would you be okay with a local pow10 function within scmi-hwmon.c and a > subsequent patch series providing a common function? >
I would prefer that, actually, to reduce dependencies.
Thanks, Guenter
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