powerpc/mpc8xxx: Allow override DDR read-to-write turnaround time
Add this option to allow boards to override the default read-to-write
turnaround time for better performance.
Signed-off-by: York Sun <yorksun@freescale.com>
diff --git a/arch/powerpc/cpu/mpc8xxx/ddr/ctrl_regs.c b/arch/powerpc/cpu/mpc8xxx/ddr/ctrl_regs.c
index 02d069c..3824aad 100644
--- a/arch/powerpc/cpu/mpc8xxx/ddr/ctrl_regs.c
+++ b/arch/powerpc/cpu/mpc8xxx/ddr/ctrl_regs.c
@@ -267,6 +267,9 @@
tmrd_mclk = 2;
#endif
+ if (popts->trwt_override)
+ trwt_mclk = popts->trwt;
+
ddr->timing_cfg_0 = (0
| ((trwt_mclk & 0x3) << 30) /* RWT */
| ((twrt_mclk & 0x3) << 28) /* WRT */
diff --git a/arch/powerpc/include/asm/fsl_ddr_sdram.h b/arch/powerpc/include/asm/fsl_ddr_sdram.h
index 1778cc5..bc063ea 100644
--- a/arch/powerpc/include/asm/fsl_ddr_sdram.h
+++ b/arch/powerpc/include/asm/fsl_ddr_sdram.h
@@ -271,6 +271,9 @@
unsigned int rcw_2;
/* control register 1 */
unsigned int ddr_cdr1;
+
+ unsigned int trwt_override;
+ unsigned int trwt; /* read-to-write turnaround */
} memctl_options_t;
extern phys_size_t fsl_ddr_sdram(void);