board: sama5d2_xplained: Make SPL work on spiflash

Because before switching to a lower clock source, we must switch
the clock source first instead of last. So before configuring the
PMC_MCKR register, invoke at91_mck_init_down() first.

As said in datasheet, the the size of SPL must not exceed the maximum
size allowed(64Kbytes).

Signed-off-by: Wenyou Yang <wenyou.yang@microchip.com>
Reviewed-by: Simon Glass <sjg@chromium.org>

board/atmel/sama5d2_xplained/sama5d2_xplained.c

@@ -247,6 +247,16 @@ void at91_pmc_init(void)
 	struct at91_pmc *pmc = (struct at91_pmc *)ATMEL_BASE_PMC;
 	u32 tmp;
 
+	/*
+	 * while coming from the ROM code, we run on PLLA @ 492 MHz / 164 MHz
+	 * so we need to slow down and configure MCKR accordingly.
+	 * This is why we have a special flavor of the switching function.
+	 */
+	tmp = AT91_PMC_MCKR_PLLADIV_2 |
+	      AT91_PMC_MCKR_MDIV_3 |
+	      AT91_PMC_MCKR_CSS_MAIN;
+	at91_mck_init_down(tmp);
+
 	tmp = AT91_PMC_PLLAR_29 |
 	      AT91_PMC_PLLXR_PLLCOUNT(0x3f) |
 	      AT91_PMC_PLLXR_MUL(82) |

include/configs/sama5d2_xplained.h

@@ -61,7 +61,7 @@
 /* SPL */
 #define CONFIG_SPL_FRAMEWORK
 #define CONFIG_SPL_TEXT_BASE		0x200000
-#define CONFIG_SPL_MAX_SIZE		0x18000
+#define CONFIG_SPL_MAX_SIZE		0x10000
 #define CONFIG_SPL_BSS_START_ADDR	0x20000000
 #define CONFIG_SPL_BSS_MAX_SIZE		0x80000
 #define CONFIG_SYS_SPL_MALLOC_START	0x20080000