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>

README

@@ -423,6 +423,11 @@ The following options need to be configured:
 		CONFIG_SYS_FSL_DSP_CCSRBAR_DEFAULT
 		This value denotes start offset of DSP CCSR space.
 
+		CONFIG_SYS_FSL_SINGLE_SOURCE_CLK
+		Single Source Clock is clocking mode present in some of FSL SoC's.
+		In this mode, a single differential clock is used to supply
+		clocks to the sysclock, ddrclock and usbclock.
+
 - Generic CPU options:
 		CONFIG_SYS_BIG_ENDIAN, CONFIG_SYS_LITTLE_ENDIAN
 

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;

arch/powerpc/include/asm/config_mpc85xx.h

@@ -711,6 +711,7 @@ defined(CONFIG_PPC_T1020) || defined(CONFIG_PPC_T1022)
 #define CONFIG_FM_PLAT_CLK_DIV	1
 #define CONFIG_SYS_FM1_CLK		CONFIG_FM_PLAT_CLK_DIV
 #define CONFIG_SYS_FM_MURAM_SIZE	0x30000
+#define CONFIG_SYS_FSL_SINGLE_SOURCE_CLK
 #define CONFIG_SYS_FSL_TBCLK_DIV	16
 #define CONFIG_SYS_FSL_PCIE_COMPAT	"fsl,qoriq-pcie-v2.4"
 #define CONFIG_SYS_FSL_USB1_PHY_ENABLE

arch/powerpc/include/asm/immap_85xx.h

@@ -1774,6 +1774,9 @@ defined(CONFIG_PPC_T1020) || defined(CONFIG_PPC_T1022)
 #define FSL_CORENET2_RCWSR5_SRDS_PLL_PD_S3_PLL2	0x00040000
 #define FSL_CORENET2_RCWSR5_SRDS_PLL_PD_S4_PLL1	0x00020000
 #define FSL_CORENET2_RCWSR5_SRDS_PLL_PD_S4_PLL2	0x00010000
+#define FSL_CORENET2_RCWSR5_DDR_REFCLK_SEL_SHIFT 4
+#define FSL_CORENET2_RCWSR5_DDR_REFCLK_SEL_MASK	0x00000011
+#define FSL_CORENET2_RCWSR5_DDR_REFCLK_SINGLE_CLK	1
 
 #else /* CONFIG_SYS_FSL_QORIQ_CHASSIS2 */
 #define FSL_CORENET_RCWSR0_MEM_PLL_RAT_SHIFT	17