[RFT PATCH v2] mtd: ixp4xx: Unrequire CONFIG_MTD_CFI_BE_BYTE_SWAP

[RFT PATCH v2] mtd: ixp4xx: Unrequire CONFIG_MTD_CFI_BE_BYTE_SWAP

[Aaron Sierra]

The .swap member of the map_info structure is provided for situations
where a mapping must always be big or little endian regardless of the
endianness of the system performing the access.

Signed-off-by: Aaron Sierra <asierra@xes-inc.com>
---
v2: Account for 32-bit swapping

 drivers/mtd/maps/ixp4xx.c | 35 ++++++++++++-----------------------
 1 file changed, 12 insertions(+), 23 deletions(-)

diff --git a/drivers/mtd/maps/ixp4xx.c b/drivers/mtd/maps/ixp4xx.c
index 6a589f1..541727e 100644
--- a/drivers/mtd/maps/ixp4xx.c
+++ b/drivers/mtd/maps/ixp4xx.c
@@ -26,6 +26,7 @@
 #include <linux/mtd/mtd.h>
 #include <linux/mtd/map.h>
 #include <linux/mtd/partitions.h>
+#include <linux/mtd/cfi_endian.h>
 
 #include <asm/io.h>
 #include <asm/mach/flash.h>
@@ -48,43 +49,30 @@
  *     | C | D | 2
  *     +---+---+
  * This means that on LE systems each 16 bit word must be swapped. Note that
- * this requires CONFIG_MTD_CFI_BE_BYTE_SWAP to be enabled to 'unswap' the CFI
- * data and other flash commands which are always in D7-D0.
+ * this is accounted for by defining map_info.swap to be CFI_BIG_ENDIAN to
+ * 'unswap' the CFI commands and using cpu_to_be16/be16_to_cpu to 'unswap'
+ * the data.
  */
-#ifndef __ARMEB__
-#ifndef CONFIG_MTD_CFI_BE_BYTE_SWAP
-#  error CONFIG_MTD_CFI_BE_BYTE_SWAP required
+
+#ifdef __ARMEB__
+#define fixup_32(io) (io)
+#else
+#define fixup_32(io) (void __iomem *)((unsigned long)(io) ^ 2)
 #endif
 
 static inline u16 flash_read16(void __iomem *addr)
 {
-	return be16_to_cpu(__raw_readw((void __iomem *)((unsigned long)addr ^ 0x2)));
+	return be16_to_cpu(__raw_readw(fixup_32(addr)));
 }
 
 static inline void flash_write16(u16 d, void __iomem *addr)
 {
-	__raw_writew(cpu_to_be16(d), (void __iomem *)((unsigned long)addr ^ 0x2));
+	__raw_writew(cpu_to_be16(d), fixup_32(addr));
 }
 
 #define	BYTE0(h)	((h) & 0xFF)
 #define	BYTE1(h)	(((h) >> 8) & 0xFF)
 
-#else
-
-static inline u16 flash_read16(const void __iomem *addr)
-{
-	return __raw_readw(addr);
-}
-
-static inline void flash_write16(u16 d, void __iomem *addr)
-{
-	__raw_writew(d, addr);
-}
-
-#define	BYTE0(h)	(((h) >> 8) & 0xFF)
-#define	BYTE1(h)	((h) & 0xFF)
-#endif
-
 static map_word ixp4xx_read16(struct map_info *map, unsigned long ofs)
 {
 	map_word val;
@@ -200,6 +188,7 @@ static int ixp4xx_flash_probe(struct platform_device *dev)
 	 * Tell the MTD layer we're not 1:1 mapped so that it does
 	 * not attempt to do a direct access on us.
 	 */
+	info->map.swap = CFI_BIG_ENDIAN;
 	info->map.phys = NO_XIP;
 	info->map.size = resource_size(dev->resource);
 
-- 
1.9.1

[RFT PATCH v2] mtd: ixp4xx: Unrequire CONFIG_MTD_CFI_BE_BYTE_SWAP

[Krzysztof Hałasa]

Aaron Sierra <asierra@xes-inc.com> writes:

> The .swap member of the map_info structure is provided for situations
> where a mapping must always be big or little endian regardless of the
> endianness of the system performing the access.

I like the idea but the patch doesn't work :-(

Without the patch:
IXP4XX-Flash.0: Found 1 x16 devices at 0x0 in 16-bit bank. Manufacturer ID 0x000089 Chip ID 0x008922
Intel/Sharp Extended Query Table at 0x010A
Intel/Sharp Extended Query Table at 0x010A
Intel/Sharp Extended Query Table at 0x010A
Intel/Sharp Extended Query Table at 0x010A
Intel/Sharp Extended Query Table at 0x010A
Using buffer write method
Using auto-unlock on power-up/resume
cfi_cmdset_0001: Erase suspend on write enabled
Searching for RedBoot partition table in IXP4XX-Flash.0 at offset 0x1fe0000
5 RedBoot partitions found on MTD device IXP4XX-Flash.0

With the patch applied:
IXP4XX-Flash.0: Found 1 x16 devices at 0x0 in 16-bit bank. Manufacturer ID 0x000089 Chip ID 0x008922
Intel/Sharp Extended Query Table at 0x010A
Intel/Sharp Extended Query Table at 0x010A
Intel/Sharp Extended Query Table at 0x010A
Intel/Sharp Extended Query Table at 0x010A
Intel/Sharp Extended Query Table at 0x010A
Using buffer write method
Using auto-unlock on power-up/resume
cfi_cmdset_0001: Erase suspend on write enabled
Searching for RedBoot partition table in IXP4XX-Flash.0 at offset 0x1fe0000
No RedBoot partition table detected in IXP4XX-Flash.0

> +++ b/drivers/mtd/maps/ixp4xx.c

> -#ifndef __ARMEB__
> -#ifndef CONFIG_MTD_CFI_BE_BYTE_SWAP
> -#  error CONFIG_MTD_CFI_BE_BYTE_SWAP required
> +
> +#ifdef __ARMEB__
> +#define fixup_32(io) (io)
> +#else
> +#define fixup_32(io) (void __iomem *)((unsigned long)(io) ^ 2)
>  #endif
>
>  static inline u16 flash_read16(void __iomem *addr)
>  {
> -	return be16_to_cpu(__raw_readw((void __iomem *)((unsigned long)addr ^ 0x2)));
> +	return be16_to_cpu(__raw_readw(fixup_32(addr)));
>  }
>
>  static inline void flash_write16(u16 d, void __iomem *addr)
>  {
> -	__raw_writew(cpu_to_be16(d), (void __iomem *)((unsigned long)addr ^ 0x2));
> +	__raw_writew(cpu_to_be16(d), fixup_32(addr));
>  }

The above change seems fine.

>  #define	BYTE0(h)	((h) & 0xFF)
>  #define	BYTE1(h)	(((h) >> 8) & 0xFF)
>
> -#else
...
> -#define	BYTE0(h)	(((h) >> 8) & 0xFF)
> -#define	BYTE1(h)	((h) & 0xFF)
> -#endif

This is used by ixp4xx_copy_from(). I don't exactly know what is MTD
layer going to do with map.swap = CFI_BIG_ENDIAN, but I think the
natural thing (= big endian on this CPU) is to copy data in big-endian
order, and then maybe (in LE mode) swap it.

In fact, it detects those RedBoot partitions when I use the original BE
BYTE0/BYTE1 macros (this second set, deleted by your patch).
Tested in BE mode only for now, can't give it more time at the moment
but will do soon.

CONFIG_MTD_CFI=y
CONFIG_MTD_CFI_ADV_OPTIONS=y
CONFIG_MTD_CFI_NOSWAP=y
# CONFIG_MTD_CFI_BE_BYTE_SWAP is not set
# CONFIG_MTD_CFI_LE_BYTE_SWAP is not set
CONFIG_MTD_CFI_GEOMETRY=y
CONFIG_MTD_CFI_I1=y
# CONFIG_MTD_CFI_I2 is not set
# CONFIG_MTD_CFI_I4 is not set
# CONFIG_MTD_CFI_I8 is not set
CONFIG_MTD_CFI_INTELEXT=y
# CONFIG_MTD_CFI_AMDSTD is not set
# CONFIG_MTD_CFI_STAA is not set
CONFIG_MTD_CFI_UTIL=y

-- 
Krzysztof Halasa

Research Institute for Automation and Measurements PIAP
Al. Jerozolimskie 202, 02-486 Warsaw, Poland

[RFT PATCH v2] mtd: ixp4xx: Unrequire CONFIG_MTD_CFI_BE_BYTE_SWAP

[Aaron Sierra]

----- Original Message -----
> From: "Krzysztof Ha?asa" <khalasa@piap.pl>
> Sent: Monday, September 29, 2014 2:50:08 AM
> 
> Aaron Sierra <asierra@xes-inc.com> writes:
> 
> > The .swap member of the map_info structure is provided for situations
> > where a mapping must always be big or little endian regardless of the
> > endianness of the system performing the access.
> 
> I like the idea but the patch doesn't work :-(
> 
> Without the patch:
> IXP4XX-Flash.0: Found 1 x16 devices at 0x0 in 16-bit bank. Manufacturer ID
> 0x000089 Chip ID 0x008922
> Intel/Sharp Extended Query Table at 0x010A
> Intel/Sharp Extended Query Table at 0x010A
> Intel/Sharp Extended Query Table at 0x010A
> Intel/Sharp Extended Query Table at 0x010A
> Intel/Sharp Extended Query Table at 0x010A
> Using buffer write method
> Using auto-unlock on power-up/resume
> cfi_cmdset_0001: Erase suspend on write enabled
> Searching for RedBoot partition table in IXP4XX-Flash.0 at offset 0x1fe0000
> 5 RedBoot partitions found on MTD device IXP4XX-Flash.0
> 
> With the patch applied:
> IXP4XX-Flash.0: Found 1 x16 devices at 0x0 in 16-bit bank. Manufacturer ID
> 0x000089 Chip ID 0x008922
> Intel/Sharp Extended Query Table at 0x010A
> Intel/Sharp Extended Query Table at 0x010A
> Intel/Sharp Extended Query Table at 0x010A
> Intel/Sharp Extended Query Table at 0x010A
> Intel/Sharp Extended Query Table at 0x010A
> Using buffer write method
> Using auto-unlock on power-up/resume
> cfi_cmdset_0001: Erase suspend on write enabled
> Searching for RedBoot partition table in IXP4XX-Flash.0 at offset 0x1fe0000
> No RedBoot partition table detected in IXP4XX-Flash.0
> 
> > +++ b/drivers/mtd/maps/ixp4xx.c
> 

[ snip agreed code ]

> 
> >  #define	BYTE0(h)	((h) & 0xFF)
> >  #define	BYTE1(h)	(((h) >> 8) & 0xFF)
> >
> > -#else
> ...
> > -#define	BYTE0(h)	(((h) >> 8) & 0xFF)
> > -#define	BYTE1(h)	((h) & 0xFF)
> > -#endif
> 
> This is used by ixp4xx_copy_from(). I don't exactly know what is MTD
> layer going to do with map.swap = CFI_BIG_ENDIAN, but I think the
> natural thing (= big endian on this CPU) is to copy data in big-endian
> order, and then maybe (in LE mode) swap it.

Your guess regarding .swap is correct. The swapping is performed by
inline functions defined in include/linux/mtd/cfi.h via
cfiX_to_cpu/cpu_to_cfiX macros.

> 
> In fact, it detects those RedBoot partitions when I use the original BE
> BYTE0/BYTE1 macros (this second set, deleted by your patch).
> Tested in BE mode only for now, can't give it more time at the moment
> but will do soon.

Thanks Krzysztof, I see what I did wrong. I will submit a new patch that
defines BYTE0/BYTE1 to work for both endian modes.

-Aaron