powerpc/mpc85xx: Add workaround for erratum A007212

Erratum A007212 for DDR is about a runaway condition for DDR PLL
oscilliator. Please refer to erratum document for detail.
For this workaround to work, DDR PLL needs to be disabled in RCW.
However, u-boot needs to know the expected PLL ratio. We put the
ratio in a reserved field RCW[18:23]. U-boot will skip this workaround
if DDR PLL ratio is set, or the reserved field is not set.

Workaround for erratum A007212 applies to selected versions of
B4/T4 SoCs. It is safe to apply the workaround to all versions. It
is helpful for upgrading SoC without changing u-boot. In case DDR
PLL is disabled by RCW (part of the erratum workaround), we need this
u-boot workround to bring up DDR clock.

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

1 files changed, 19 insertions, 0 deletions

diff --git a/arch/powerpc/cpu/mpc85xx/cmd_errata.c b/arch/powerpc/cpu/mpc85xx/cmd_errata.c
index ee063fd8e9..9d8acd0aa1 100644
--- a/arch/powerpc/cpu/mpc85xx/cmd_errata.c
+++ b/arch/powerpc/cpu/mpc85xx/cmd_errata.c
@@ -113,6 +113,21 @@ static void check_erratum_a4580(uint32_t svr)
 }
 #endif
 
+#ifdef CONFIG_SYS_FSL_ERRATUM_A007212
+/*
+ * This workaround can be implemented in PBI, or by u-boot.
+ */
+static void check_erratum_a007212(void)
+{
+	u32 __iomem *plldgdcr = (void *)(CONFIG_SYS_DCSRBAR + 0x21c20);
+
+	if (in_be32(plldgdcr) & 0x1fe) {
+		/* check if PLL ratio is set by workaround */
+		puts("Work-around for Erratum A007212 enabled\n");
+	}
+}
+#endif
+
 static int do_errata(cmd_tbl_t *cmdtp, int flag, int argc, char * const argv[])
 {
 #ifdef CONFIG_SYS_FSL_ERRATUM_NMG_CPU_A011
@@ -281,6 +296,10 @@ static int do_errata(cmd_tbl_t *cmdtp, int flag, int argc, char * const argv[])
 	if (has_erratum_a006261())
 		puts("Work-around for Erratum A006261 enabled\n");
 #endif
+#ifdef CONFIG_SYS_FSL_ERRATUM_A007212
+	check_erratum_a007212();
+#endif
+
 	return 0;
 }