MIPS: BMIPS: Move post DMA flush implementation to common header

arch/mips/include/asm/mach-bmips/dma-coherence.h contains the
plat_post_dma_flush implementation which is not specific to mach-bmips,
but required for all BMIPS-based systems.

Move plat_post_dma_flush to arch/mips/include/asm/bmips.h, rename it to
bmips_post_dma_flush such that other platforms like bcm63xx can utilize
it.

Signed-off-by: Florian Fainelli <f.fainelli@gmail.com>
Cc: linux-mips@linux-mips.org
Cc: cernekee@gmail.com
Cc: jogo@openwrt.org
Patchwork: https://patchwork.linux-mips.org/patch/9724/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
diff --git a/arch/mips/include/asm/bmips.h b/arch/mips/include/asm/bmips.h
index 30939b0..6d25ad3 100644
--- a/arch/mips/include/asm/bmips.h
+++ b/arch/mips/include/asm/bmips.h
@@ -122,6 +122,22 @@
 	barrier();
 }
 
+static inline void bmips_post_dma_flush(struct device *dev)
+{
+	void __iomem *cbr = BMIPS_GET_CBR();
+	u32 cfg;
+
+	if (boot_cpu_type() != CPU_BMIPS3300 &&
+	    boot_cpu_type() != CPU_BMIPS4350 &&
+	    boot_cpu_type() != CPU_BMIPS4380)
+		return;
+
+	/* Flush stale data out of the readahead cache */
+	cfg = __raw_readl(cbr + BMIPS_RAC_CONFIG);
+	__raw_writel(cfg | 0x100, cbr + BMIPS_RAC_CONFIG);
+	__raw_readl(cbr + BMIPS_RAC_CONFIG);
+}
+
 #endif /* !defined(__ASSEMBLY__) */
 
 #endif /* _ASM_BMIPS_H */