armv8/fsl-lsch3: Implement workaround for erratum A008585

Generic Timer may contain an erroneous value. The workaround is to
read it twice until getting the same value.

Signed-off-by: York Sun <yorksun@freescale.com>

arch/arm/cpu/armv8/generic_timer.c

@@ -25,7 +25,18 @@ unsigned long get_tbclk(void)
 unsigned long timer_read_counter(void)
 {
 	unsigned long cntpct;
+#ifdef CONFIG_SYS_FSL_ERRATUM_A008585
+	/* This erratum number needs to be confirmed to match ARM document */
+	unsigned long temp;
+#endif
 	isb();
 	asm volatile("mrs %0, cntpct_el0" : "=r" (cntpct));
+#ifdef CONFIG_SYS_FSL_ERRATUM_A008585
+	asm volatile("mrs %0, cntpct_el0" : "=r" (temp));
+	while (temp != cntpct) {
+		asm volatile("mrs %0, cntpct_el0" : "=r" (cntpct));
+		asm volatile("mrs %0, cntpct_el0" : "=r" (temp));
+	}
+#endif
 	return cntpct;
 }

arch/arm/include/asm/arch-fsl-lsch3/config.h

@@ -120,6 +120,7 @@
 #ifdef CONFIG_LS2085A
 #define CONFIG_SYS_FSL_ERRATUM_A008336
 #define CONFIG_SYS_FSL_ERRATUM_A008514
+#define CONFIG_SYS_FSL_ERRATUM_A008585
 #endif
 
 #endif /* _ASM_ARMV8_FSL_LSCH3_CONFIG_ */