mtd: Make MTD_BCM47XXSFLASH to depend on MIPS

The bcm47xxsflash driver uses the KSEG0ADDR() function to map an address
to a certain kernel segment. But that is only defined if the MIPS config
symbol is enabled. The driver does not have an explicit dependency on it
and relies on a transitive dependency relation:

MTD_BCM47XXSFLASH -> BCMA_SFLASH -> BCMA_DRIVER_MIPS -> BCMA && MIPS

But BCMA_SFLASH and BCMA_DRIVER_MIPS have only runtime and not buildtime
dependency with MIPS so can be changed to be built test using the config
COMPILE_TEST symbol. But that would make MTD_BCM47XXSFLASH be built with
MIPS not enabled and cause the following build error:

drivers/mtd/devices//bcm47xxsflash.c: In function 'bcm47xxsflash_read':
drivers/mtd/devices//bcm47xxsflash.c:112:2: error: implicit declaration of function 'KSEG0ADDR' [-Werror=implicit-function-declaration]
  memcpy_fromio(buf, (void __iomem *)KSEG0ADDR(b47s->window + from),
  ^

Make MTD_BCM47XXSFLASH depend on MIPS since has a buildtime dependency.

Reported-by: Fengguang Wu <fengguang.wu@intel.com>
Signed-off-by: Javier Martinez Canillas <javier@osg.samsung.com>

---

 drivers/mtd/devices/Kconfig | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

+ Rafał

On Wed, Oct 14, 2015 at 11:04:54AM +0200, Javier Martinez Canillas wrote:
> The bcm47xxsflash driver uses the KSEG0ADDR() function to map an address
> to a certain kernel segment. But that is only defined if the MIPS config
> symbol is enabled. The driver does not have an explicit dependency on it
> and relies on a transitive dependency relation:
> 
> MTD_BCM47XXSFLASH -> BCMA_SFLASH -> BCMA_DRIVER_MIPS -> BCMA && MIPS
> 
> But BCMA_SFLASH and BCMA_DRIVER_MIPS have only runtime and not buildtime
> dependency with MIPS so can be changed to be built test using the config
> COMPILE_TEST symbol. But that would make MTD_BCM47XXSFLASH be built with
> MIPS not enabled and cause the following build error:
> 
> drivers/mtd/devices//bcm47xxsflash.c: In function 'bcm47xxsflash_read':
> drivers/mtd/devices//bcm47xxsflash.c:112:2: error: implicit declaration of function 'KSEG0ADDR' [-Werror=implicit-function-declaration]
>   memcpy_fromio(buf, (void __iomem *)KSEG0ADDR(b47s->window + from),
>   ^
> 
> Make MTD_BCM47XXSFLASH depend on MIPS since has a buildtime dependency.
> 
> Reported-by: Fengguang Wu <fengguang.wu@intel.com>
> Signed-off-by: Javier Martinez Canillas <javier@osg.samsung.com>
> 
> ---
> 
>  drivers/mtd/devices/Kconfig | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/mtd/devices/Kconfig b/drivers/mtd/devices/Kconfig
> index f73c41697a00..f5eab3c19356 100644
> --- a/drivers/mtd/devices/Kconfig
> +++ b/drivers/mtd/devices/Kconfig
> @@ -114,7 +114,7 @@ config MTD_SST25L
>  
>  config MTD_BCM47XXSFLASH
>  	tristate "R/O support for serial flash on BCMA bus"
> -	depends on BCMA_SFLASH
> +	depends on BCMA_SFLASH && MIPS
>  	help
>  	  BCMA bus can have various flash memories attached, they are
>  	  registered by bcma as platform devices. This enables driver for
> -- 
> 2.4.3
>

On 14 October 2015 at 11:04, Javier Martinez Canillas
<javier@osg.samsung.com> wrote:
> The bcm47xxsflash driver uses the KSEG0ADDR() function to map an address
> to a certain kernel segment. But that is only defined if the MIPS config
> symbol is enabled. The driver does not have an explicit dependency on it
> and relies on a transitive dependency relation:
>
> MTD_BCM47XXSFLASH -> BCMA_SFLASH -> BCMA_DRIVER_MIPS -> BCMA && MIPS
>
> But BCMA_SFLASH and BCMA_DRIVER_MIPS have only runtime and not buildtime
> dependency with MIPS so can be changed to be built test using the config
> COMPILE_TEST symbol. But that would make MTD_BCM47XXSFLASH be built with
> MIPS not enabled and cause the following build error:
>
> drivers/mtd/devices//bcm47xxsflash.c: In function 'bcm47xxsflash_read':
> drivers/mtd/devices//bcm47xxsflash.c:112:2: error: implicit declaration of function 'KSEG0ADDR' [-Werror=implicit-function-declaration]
>   memcpy_fromio(buf, (void __iomem *)KSEG0ADDR(b47s->window + from),

I think we're not really supposed to use KSEG0ADDR anyway. What about
replacing it with ioremap_nocache?

Sorry for the late reply.

On Wed, Nov 04, 2015 at 10:04:26AM +0100, Rafał Miłecki wrote:
> On 14 October 2015 at 11:04, Javier Martinez Canillas
> <javier@osg.samsung.com> wrote:
> > The bcm47xxsflash driver uses the KSEG0ADDR() function to map an address
> > to a certain kernel segment. But that is only defined if the MIPS config
> > symbol is enabled. The driver does not have an explicit dependency on it
> > and relies on a transitive dependency relation:
> >
> > MTD_BCM47XXSFLASH -> BCMA_SFLASH -> BCMA_DRIVER_MIPS -> BCMA && MIPS
> >
> > But BCMA_SFLASH and BCMA_DRIVER_MIPS have only runtime and not buildtime
> > dependency with MIPS so can be changed to be built test using the config
> > COMPILE_TEST symbol. But that would make MTD_BCM47XXSFLASH be built with
> > MIPS not enabled and cause the following build error:
> >
> > drivers/mtd/devices//bcm47xxsflash.c: In function 'bcm47xxsflash_read':
> > drivers/mtd/devices//bcm47xxsflash.c:112:2: error: implicit declaration of function 'KSEG0ADDR' [-Werror=implicit-function-declaration]
> >   memcpy_fromio(buf, (void __iomem *)KSEG0ADDR(b47s->window + from),
> 
> I think we're not really supposed to use KSEG0ADDR anyway. What about
> replacing it with ioremap_nocache?

I'm not really a MIPS expert, but isn't KSEG0 actually *cached*? (And is
that correct, then?)

AIUI, ioremap_nocache() will actually get you a KSEG1 address here, I
think.

Also (a bit of a tangent) couldn't "window" be better passed as a second
resource by drivers/bcma/driver_chipcommon_sflash.c? Seems like that
would fit the device/resource model better, and then you wouldn't have
to do any __iomem casts in bcm47xxsflash.c.

Brian

On Wed, 4 Nov 2015, Brian Norris wrote:

> > > The bcm47xxsflash driver uses the KSEG0ADDR() function to map an address
> > > to a certain kernel segment. But that is only defined if the MIPS config
> > > symbol is enabled. The driver does not have an explicit dependency on it
> > > and relies on a transitive dependency relation:
> > >
> > > MTD_BCM47XXSFLASH -> BCMA_SFLASH -> BCMA_DRIVER_MIPS -> BCMA && MIPS
> > >
> > > But BCMA_SFLASH and BCMA_DRIVER_MIPS have only runtime and not buildtime
> > > dependency with MIPS so can be changed to be built test using the config
> > > COMPILE_TEST symbol. But that would make MTD_BCM47XXSFLASH be built with
> > > MIPS not enabled and cause the following build error:
> > >
> > > drivers/mtd/devices//bcm47xxsflash.c: In function 'bcm47xxsflash_read':
> > > drivers/mtd/devices//bcm47xxsflash.c:112:2: error: implicit declaration of function 'KSEG0ADDR' [-Werror=implicit-function-declaration]
> > >   memcpy_fromio(buf, (void __iomem *)KSEG0ADDR(b47s->window + from),
> > 
> > I think we're not really supposed to use KSEG0ADDR anyway. What about
> > replacing it with ioremap_nocache?
> 
> I'm not really a MIPS expert, but isn't KSEG0 actually *cached*? (And is
> that correct, then?)
> 
> AIUI, ioremap_nocache() will actually get you a KSEG1 address here, I
> think.

 Depending on configuration `ioremap_nocache' may give you a KSEG1, an 
XKPHYS or an uncached virtual (KSEG2) address.  Drivers are not supposed 
to use KSEG0ADDR, etc. macros, these are only for low-level core platform 
code.  Besides, KSEG0ADDR is not portable to 64-bit systems -- which may 
not be an issue here, but still this means it shouldn't appear in a driver 
as this causes a portability and maintenance issue.

 Use plain `ioremap' instead for a cached MMIO mapping; of course you need 
to place it elsewhere as at the very least you need to `iounmap' the area 
mappad later on.  In most cases it makes sense to handle the mapping and 
unmapping in device initialisation and shutdown respectively, and then 
carry the pointer obtained through and use it throughout the use of the 
device.

 HTH,

  Maciej