On 11/27/2013 09:34 PM, Priyanka Jain wrote:
Single-source clocking is new feature introduced in T1040. In this mode, a 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-sourec clocking 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
arch/powerpc/cpu/mpc85xx/speed.c | 20 ++++++++++++++++++++ arch/powerpc/include/asm/config_mpc85xx.h | 1 + arch/powerpc/include/asm/immap_85xx.h | 3 +++ 3 files changed, 24 insertions(+), 0 deletions(-)
diff --git a/arch/powerpc/cpu/mpc85xx/speed.c b/arch/powerpc/cpu/mpc85xx/speed.c index 1a58a19..cd49695 100644 --- a/arch/powerpc/cpu/mpc85xx/speed.c +++ b/arch/powerpc/cpu/mpc85xx/speed.c @@ -77,7 +77,27 @@ void get_sys_info(sys_info_t *sys_info)
sys_info->freq_systembus = sysclk; #ifdef CONFIG_DDR_CLK_FREQ
Do you think it is right to put the single clock detection here? This macro CONFIG_DDR_CLK_FREQ is used when a dedicated DDR reference clock is used. In case the DIFF_SYSCLK is used, you don't have to have a DDR reference clock, do you?
+#ifdef CONFIG_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.*/- uint single_src;
- 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)
sys_info->freq_ddrbus = CONFIG_SYS_CLK_FREQ;- else
sys_info->freq_ddrbus = CONFIG_DDR_CLK_FREQ;+#else sys_info->freq_ddrbus = CONFIG_DDR_CLK_FREQ; +#endif #else sys_info->freq_ddrbus = sysclk; #endif
My point is you probably don't have to define CONFIG_DDR_CLK_FREQ to use single source clock.
York