MIPS: SMP-CPS: Fix address for GCR_ACCESS register for CM3 and later

When the CM block migrated from CM2.5 to CM3.0, the address offset for
the Global CSR Access Privilege register was modified. We saw this in
the "MIPS64 I6500 Multiprocessing System Programmer's Guide," it is
stated that "the Global CSR Access Privilege register is located at
offset 0x0120" in section 5.4. It is at least the same for I6400.

This fix allows to use the VP cores in SMP mode if the reset values
were modified by the bootloader.

Based on the work of Vladimir Kondratiev
<[e-mail]> and the feedback from Jiaxun Yang
<[e-mail]>.

Fixes: 197e89e0984a ("MIPS: mips-cm: Implement mips_cm_revision")
Signed-off-by: Gregory CLEMENT <[e-mail]>
Reviewed-by: Jiaxun Yang <[e-mail]>
Signed-off-by: Thomas Bogendoerfer <[e-mail]>

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

···
 GCR_ACCESSOR_RO(32, 0x0f0, cpc_status)
 #define CM_GCR_CPC_STATUS_EX			BIT(0)
 
+/* GCR_ACCESS - Controls core/IOCU access to GCRs */
+GCR_ACCESSOR_RW(32, 0x120, access_cm3)
+#define CM_GCR_ACCESS_ACCESSEN			GENMASK(7, 0)
+
 /* GCR_L2_CONFIG - Indicates L2 cache configuration when Config5.L2C=1 */
 GCR_ACCESSOR_RW(32, 0x130, l2_config)
 #define CM_GCR_L2_CONFIG_BYPASS			BIT(20)

arch/mips/kernel/smp-cps.c

···
 	write_gcr_co_reset_ext_base(CM_GCR_Cx_RESET_EXT_BASE_UEB);
 
 	/* Ensure the core can access the GCRs */
-	set_gcr_access(1 << core);
+	if (mips_cm_revision() < CM_REV_CM3)
+		set_gcr_access(1 << core);
+	else
+		set_gcr_access_cm3(1 << core);
 
 	if (mips_cpc_present()) {
 		/* Reset the core */