| Message ID | 1445689693-21436-4-git-send-email-festevam@gmail.com |
|---|---|
| State | Superseded |
| Headers | show |
On Sat, Oct 24, 2015 at 10:28:04AM -0200, Fabio Estevam wrote: > From: Fabio Estevam <fabio.estevam@freescale.com> > > The ffs64() implementation for powerpc is not found in the Linux kernel, > so use the ffs64 header file from barebox. > > Imported from barebox v2015.10.0. > > Signed-off-by: Fabio Estevam <fabio.estevam@freescale.com> I'm confused. In the kernel __ffs64 is in <linux/bitops.h>, why do we need to do things differently here?
Hi Tom, On Sat, Oct 24, 2015 at 11:32 AM, Tom Rini <trini@konsulko.com> wrote: > On Sat, Oct 24, 2015 at 10:28:04AM -0200, Fabio Estevam wrote: > >> From: Fabio Estevam <fabio.estevam@freescale.com> >> >> The ffs64() implementation for powerpc is not found in the Linux kernel, >> so use the ffs64 header file from barebox. >> >> Imported from barebox v2015.10.0. >> >> Signed-off-by: Fabio Estevam <fabio.estevam@freescale.com> > > I'm confused. In the kernel __ffs64 is in <linux/bitops.h>, why do we > need to do things differently here? It is true that kernel uses __ffs64 from <linux/bitops.h>, however in U-boot (and barebox) there is also ffs64 for powerpc, so that's why I added a new header for it. We have no ffs64 in kernel, only __ffs64. Regards, Fabio Estevam
On Sat, Oct 24, 2015 at 11:37 AM, Fabio Estevam <festevam@gmail.com> wrote: > Hi Tom, > > On Sat, Oct 24, 2015 at 11:32 AM, Tom Rini <trini@konsulko.com> wrote: >> On Sat, Oct 24, 2015 at 10:28:04AM -0200, Fabio Estevam wrote: >> >>> From: Fabio Estevam <fabio.estevam@freescale.com> >>> >>> The ffs64() implementation for powerpc is not found in the Linux kernel, >>> so use the ffs64 header file from barebox. >>> >>> Imported from barebox v2015.10.0. >>> >>> Signed-off-by: Fabio Estevam <fabio.estevam@freescale.com> >> >> I'm confused. In the kernel __ffs64 is in <linux/bitops.h>, why do we >> need to do things differently here? > > It is true that kernel uses __ffs64 from <linux/bitops.h>, however in > U-boot (and barebox) there is also ffs64 for powerpc, so that's why I > added a new header for it. > > We have no ffs64 in kernel, only __ffs64. After thinking more about it, I think we can simply use __ffs64 for powerpc as well. There is no assembly optimzation for ffs64 so we can use the generic __ffs64. Will prepare a new version doing this. Thanks
On Sat, Oct 24, 2015 at 12:54:40PM -0200, Fabio Estevam wrote: > On Sat, Oct 24, 2015 at 11:37 AM, Fabio Estevam <festevam@gmail.com> wrote: > > Hi Tom, > > > > On Sat, Oct 24, 2015 at 11:32 AM, Tom Rini <trini@konsulko.com> wrote: > >> On Sat, Oct 24, 2015 at 10:28:04AM -0200, Fabio Estevam wrote: > >> > >>> From: Fabio Estevam <fabio.estevam@freescale.com> > >>> > >>> The ffs64() implementation for powerpc is not found in the Linux kernel, > >>> so use the ffs64 header file from barebox. > >>> > >>> Imported from barebox v2015.10.0. > >>> > >>> Signed-off-by: Fabio Estevam <fabio.estevam@freescale.com> > >> > >> I'm confused. In the kernel __ffs64 is in <linux/bitops.h>, why do we > >> need to do things differently here? > > > > It is true that kernel uses __ffs64 from <linux/bitops.h>, however in > > U-boot (and barebox) there is also ffs64 for powerpc, so that's why I > > added a new header for it. > > > > We have no ffs64 in kernel, only __ffs64. > > After thinking more about it, I think we can simply use __ffs64 for > powerpc as well. > > There is no assembly optimzation for ffs64 so we can use the generic __ffs64. > > Will prepare a new version doing this. Thanks That's what I was hoping for, thanks!
diff --git a/arch/powerpc/include/asm/ffs64.h b/arch/powerpc/include/asm/ffs64.h new file mode 100644 index 0000000..620874c --- /dev/null +++ b/arch/powerpc/include/asm/ffs64.h @@ -0,0 +1,12 @@ +/* + * Copyright 2013 GE Intelligent Platforms, Inc. + * + * SPDX-License-Identifier: GPL-2.0+ + * + */ +#include <linux/log2.h> + +static inline int ffs64(u64 x) +{ + return __ilog2_u64(x & -x) + 1ull; +}