MIPS: smp-cps: Ensure secondary cores start with EVA disabled

The kernel currently assumes that a core will start up in legacy mode
using the exception base provided through the CM GCR registers. If a
core has been configured in hardware to start in EVA mode, these
assumptions will fail.

This patch ensures that secondary cores are initialized to meet these
assumptions.
Signed-off-by: Matt Redfearn <matt.redfearn@imgtec.com>
Reviewed-by: Paul Burton <paul.burton@imgtec.com>
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/11907/Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

arch/mips/include/asm/mips-cm.h

@@ -243,6 +243,10 @@ BUILD_CM_Cx_R_(tcid_8_priority,	0x80)
 #define  CM_GCR_BASE_CMDEFTGT_IOCU0		2
 #define  CM_GCR_BASE_CMDEFTGT_IOCU1		3
 
+/* GCR_RESET_EXT_BASE register fields */
+#define CM_GCR_RESET_EXT_BASE_EVARESET		BIT(31)
+#define CM_GCR_RESET_EXT_BASE_UEB		BIT(30)
+
 /* GCR_ACCESS register fields */
 #define CM_GCR_ACCESS_ACCESSEN_SHF		0
 #define CM_GCR_ACCESS_ACCESSEN_MSK		(_ULCAST_(0xff) << 0)

arch/mips/kernel/smp-cps.c

@@ -202,6 +202,9 @@ static void boot_core(unsigned core)
 	/* Ensure its coherency is disabled */
 	write_gcr_co_coherence(0);
 
+	/* Start it with the legacy memory map and exception base */
+	write_gcr_co_reset_ext_base(CM_GCR_RESET_EXT_BASE_UEB);
+
 	/* Ensure the core can access the GCRs */
 	access = read_gcr_access();
 	access |= 1 << (CM_GCR_ACCESS_ACCESSEN_SHF + core);