powerpc/mpc85xx: Add support for single source clocking

Single-source clocking is new feature introduced in T1040.
In this mode, a single differential clock is supplied to the
DIFF_SYSCLK_P/N inputs to the processor, which in turn is
used to supply clocks to the sysclock, ddrclock and usbclock.

So, both ddrclock and syclock are driven by same differential
sysclock in single-source clocking mode whereas in normal clocking
mode, generally separate DDRCLK and SYSCLK pins provides
reference clock for sysclock and ddrclock

DDR_REFCLK_SEL rcw bit is used to determine DDR clock source
-If DDR_REFCLK_SEL rcw bit is 0, then DDR PLLs are driven in
 normal clocking mode by DDR_Reference clock

-If DDR_REFCLK_SEL rcw bit is 1, then DDR PLLs are driven in
 single source clocking mode by DIFF_SYSCLK

Add code to determine ddrclock based on DDR_REFCLK_SEL rcw bit.

Signed-off-by: Poonam Aggrwal <poonam.aggrwal@freescale.com>
Signed-off-by: Priyanka Jain <Priyanka.Jain@freescale.com>

1 files changed, 23 insertions, 2 deletions

diff --git a/arch/powerpc/cpu/mpc85xx/speed.c b/arch/powerpc/cpu/mpc85xx/speed.c
index 7c7467f..35867df 100644
--- a/arch/powerpc/cpu/mpc85xx/speed.c
+++ b/arch/powerpc/cpu/mpc85xx/speed.c
@@ -74,12 +74,33 @@ void get_sys_info(sys_info_t *sys_info)
 	uint ratio[CONFIG_SYS_FSL_NUM_CC_PLLS];
 	unsigned long sysclk = CONFIG_SYS_CLK_FREQ;
 	uint mem_pll_rat;
+#ifdef CONFIG_SYS_FSL_SINGLE_SOURCE_CLK
+	uint single_src;
+#endif
 
 	sys_info->freq_systembus = sysclk;
+#ifdef CONFIG_SYS_FSL_SINGLE_SOURCE_CLK
+	/*
+	 * DDR_REFCLK_SEL rcw bit is used to determine if DDR PLLS
+	 * are driven by separate DDR Refclock or single source
+	 * differential clock.
+	 */
+	single_src = (in_be32(&gur->rcwsr[5]) >>
+		      FSL_CORENET2_RCWSR5_DDR_REFCLK_SEL_SHIFT) &
+		      FSL_CORENET2_RCWSR5_DDR_REFCLK_SEL_MASK;
+	/*
+	 * For single source clocking, both ddrclock and syclock
+	 * are driven by differential sysclock.
+	 */
+	if (single_src == FSL_CORENET2_RCWSR5_DDR_REFCLK_SINGLE_CLK) {
+		printf("Single Source Clock Configuration\n");
+		sys_info->freq_ddrbus = CONFIG_SYS_CLK_FREQ;
+	} else
+#endif
 #ifdef CONFIG_DDR_CLK_FREQ
-	sys_info->freq_ddrbus = CONFIG_DDR_CLK_FREQ;
+		sys_info->freq_ddrbus = CONFIG_DDR_CLK_FREQ;
 #else
-	sys_info->freq_ddrbus = sysclk;
+		sys_info->freq_ddrbus = sysclk;
 #endif
 
 	sys_info->freq_systembus *= (in_be32(&gur->rcwsr[0]) >> 25) & 0x1f;