diff options
| -rw-r--r-- | include/asm-arm/arch-ixp2000/platform.h | 25 |
1 files changed, 25 insertions, 0 deletions
diff --git a/include/asm-arm/arch-ixp2000/platform.h b/include/asm-arm/arch-ixp2000/platform.h index 6e5b6a955abe..a66317ab2071 100644 --- a/include/asm-arm/arch-ixp2000/platform.h +++ b/include/asm-arm/arch-ixp2000/platform.h @@ -26,6 +26,31 @@ static inline void ixp2000_reg_write(volatile void *reg, unsigned long val) } /* + * On the IXP2400, we can't use XCB=000 due to chip bugs. We use + * XCB=101 instead, but that makes all I/O accesses bufferable. This + * is not a problem in general, but we do have to be slightly more + * careful because I/O writes are no longer automatically flushed out + * of the write buffer. + * + * In cases where we want to make sure that a write has been flushed + * out of the write buffer before we proceed, for example when masking + * a device interrupt before re-enabling IRQs in CPSR, we can use this + * function, ixp2000_reg_wrb, which performs a write, a readback, and + * issues a dummy instruction dependent on the value of the readback + * (mov rX, rX) to make sure that the readback has completed before we + * continue. + */ +static inline void ixp2000_reg_wrb(volatile void *reg, unsigned long val) +{ + unsigned long dummy; + + *((volatile unsigned long *)reg) = val; + + dummy = *((volatile unsigned long *)reg); + __asm__ __volatile__("mov %0, %0" : "+r" (dummy)); +} + +/* * Boards may multiplex different devices on the 2nd channel of * the slowport interface that each need different configuration * settings. For example, the IXDP2400 uses channel 2 on the interface |