| Message ID | 1427370354-21247-2-git-send-email-ben.dooks@codethink.co.uk (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
Around Thu 26 Mar 2015 11:45:49 +0000 or thereabout, Ben Dooks wrote: > The AVR32 and ARM (AT91) architectures share a number of drivers which > need to access the on chip peripherals. The current drivers work with > the default endian configuration, however it is possilbe to run some of > the ATMEL ARM architectures in big endian mode. > > If we change the drivers from __raw to _relaxed IO accesors then the ARM > side works but the AVR32 will not. The _relaxed assume the bus is little > endian and the __raw are native. The AVR32 is native big endian so these > are not the right functions. > > To sort this out, and avoid a number of drivers having #ifdef for the > AVR32 case we add <linux/atmel_io.h> to provide some AT91/AVR32 independant > IO accessor functions. > > Signed-off-by: Ben Dooks <ben.dooks@codethink.co.uk> Acked-by: Hans-Christian Egtvedt <egtvedt@samfundet.no> > -- > CC: Haavard Skinnemoen <hskinnemoen@gmail.com> > CC: Hans-Christian Egtvedt <egtvedt@samfundet.no> > CC: Andrew Victor <linux@maxim.org.za> > CC: Nicolas Ferre <nicolas.ferre@atmel.com> > CC: linux-arm-kernel@lists.infradead.org > --- > include/linux/atmel_io.h | 25 +++++++++++++++++++++++++ > 1 file changed, 25 insertions(+) > create mode 100644 include/linux/atmel_io.h > > diff --git a/include/linux/atmel_io.h b/include/linux/atmel_io.h > new file mode 100644 > index 0000000..1234e88 > --- /dev/null > +++ b/include/linux/atmel_io.h > @@ -0,0 +1,25 @@ > +/* Atmel AT91/AVR32 independant IO > + * > + * Copyright 2015 Codethink Ltd. > + * Ben Dooks <ben.dooks@codethink.co.uk> > + * > + * Provide architecture indendant, endian-safe IO accessor functions > + */ > + > +#ifdef CONFIG_AVR32 > +/* For AVR32 the readl and writel relaxed will do an extra byte reverse > + * as the peripherals are already in the same endian-ness as the CPU and > + * readl/writel assume little endian where the CPU is big endian > + */ > +#define atmel_oc_readl __raw_readl > +#define atmel_oc_writel __raw_writel > + > +#define atmel_oc_readw __raw_readw > +#define atmel_oc_writew __raw_writew > +#else > +#define atmel_oc_readl readl_relaxed > +#define atmel_oc_writel writel_relaxed > + > +#define atmel_oc_readw readw_relaxed > +#define atmel_oc_writew writew_relaxed > +#endif
Hi, On 26/03/2015 at 12:51:23 +0100, Hans-Christian Egtvedt wrote : > Around Thu 26 Mar 2015 11:45:49 +0000 or thereabout, Ben Dooks wrote: > > The AVR32 and ARM (AT91) architectures share a number of drivers which > > need to access the on chip peripherals. The current drivers work with > > the default endian configuration, however it is possilbe to run some of > > the ATMEL ARM architectures in big endian mode. > > > > If we change the drivers from __raw to _relaxed IO accesors then the ARM > > side works but the AVR32 will not. The _relaxed assume the bus is little > > endian and the __raw are native. The AVR32 is native big endian so these > > are not the right functions. > > > > To sort this out, and avoid a number of drivers having #ifdef for the > > AVR32 case we add <linux/atmel_io.h> to provide some AT91/AVR32 independant > > IO accessor functions. > > > > Signed-off-by: Ben Dooks <ben.dooks@codethink.co.uk> > > Acked-by: Hans-Christian Egtvedt <egtvedt@samfundet.no> > Is there any reason why read/write[bwl]_relaxed can't be made to do big endian accesses on avr32?
On Sat, Mar 28, 2015 at 07:20:48PM +0100, Alexandre Belloni wrote: > Hi, > > On 26/03/2015 at 12:51:23 +0100, Hans-Christian Egtvedt wrote : > > Around Thu 26 Mar 2015 11:45:49 +0000 or thereabout, Ben Dooks wrote: > > > The AVR32 and ARM (AT91) architectures share a number of drivers which > > > need to access the on chip peripherals. The current drivers work with > > > the default endian configuration, however it is possilbe to run some of > > > the ATMEL ARM architectures in big endian mode. > > > > > > If we change the drivers from __raw to _relaxed IO accesors then the ARM > > > side works but the AVR32 will not. The _relaxed assume the bus is little > > > endian and the __raw are native. The AVR32 is native big endian so these > > > are not the right functions. > > > > > > To sort this out, and avoid a number of drivers having #ifdef for the > > > AVR32 case we add <linux/atmel_io.h> to provide some AT91/AVR32 independant > > > IO accessor functions. > > > > > > Signed-off-by: Ben Dooks <ben.dooks@codethink.co.uk> > > > > Acked-by: Hans-Christian Egtvedt <egtvedt@samfundet.no> > > > > Is there any reason why read/write[bwl]_relaxed can't be made to do big > endian accesses on avr32? read/write[bwl]* are defined to be little endian accessors - they have their roots in PCI.
diff --git a/include/linux/atmel_io.h b/include/linux/atmel_io.h new file mode 100644 index 0000000..1234e88 --- /dev/null +++ b/include/linux/atmel_io.h @@ -0,0 +1,25 @@ +/* Atmel AT91/AVR32 independant IO + * + * Copyright 2015 Codethink Ltd. + * Ben Dooks <ben.dooks@codethink.co.uk> + * + * Provide architecture indendant, endian-safe IO accessor functions + */ + +#ifdef CONFIG_AVR32 +/* For AVR32 the readl and writel relaxed will do an extra byte reverse + * as the peripherals are already in the same endian-ness as the CPU and + * readl/writel assume little endian where the CPU is big endian + */ +#define atmel_oc_readl __raw_readl +#define atmel_oc_writel __raw_writel + +#define atmel_oc_readw __raw_readw +#define atmel_oc_writew __raw_writew +#else +#define atmel_oc_readl readl_relaxed +#define atmel_oc_writel writel_relaxed + +#define atmel_oc_readw readw_relaxed +#define atmel_oc_writew writew_relaxed +#endif
The AVR32 and ARM (AT91) architectures share a number of drivers which need to access the on chip peripherals. The current drivers work with the default endian configuration, however it is possilbe to run some of the ATMEL ARM architectures in big endian mode. If we change the drivers from __raw to _relaxed IO accesors then the ARM side works but the AVR32 will not. The _relaxed assume the bus is little endian and the __raw are native. The AVR32 is native big endian so these are not the right functions. To sort this out, and avoid a number of drivers having #ifdef for the AVR32 case we add <linux/atmel_io.h> to provide some AT91/AVR32 independant IO accessor functions. Signed-off-by: Ben Dooks <ben.dooks@codethink.co.uk> -- CC: Haavard Skinnemoen <hskinnemoen@gmail.com> CC: Hans-Christian Egtvedt <egtvedt@samfundet.no> CC: Andrew Victor <linux@maxim.org.za> CC: Nicolas Ferre <nicolas.ferre@atmel.com> CC: linux-arm-kernel@lists.infradead.org --- include/linux/atmel_io.h | 25 +++++++++++++++++++++++++ 1 file changed, 25 insertions(+) create mode 100644 include/linux/atmel_io.h