MIPS: Map CM Global Control Registers

Map the Global Control Registers (GCRs) provided by the MIPS Coherence
Manager (CM) in preparation for using some of them in later patches.

Signed-off-by: Paul Burton <paul.burton@imgtec.com>

arch/mips/Kconfig

@@ -318,6 +318,22 @@ config MIPS_L1_CACHE_SHIFT
 config DYNAMIC_IO_PORT_BASE
 	bool
 
+config MIPS_CM
+	bool
+	help
+	  Select this if your system contains a MIPS Coherence Manager and you
+	  wish U-Boot to configure it or make use of it to retrieve system
+	  information such as cache configuration.
+
+config MIPS_CM_BASE
+	hex
+	default 0x1fbf8000
+	help
+	  The physical base address at which to map the MIPS Coherence Manager
+	  Global Configuration Registers (GCRs). This should be set such that
+	  the GCRs occupy a region of the physical address space which is
+	  otherwise unused, or at minimum that software doesn't need to access.
+
 endif
 
 endmenu

arch/mips/cpu/Makefile

@@ -7,3 +7,5 @@ extra-y	= start.o
 obj-y += time.o
 obj-y += interrupts.o
 obj-y += cpu.o
+
+obj-$(CONFIG_MIPS_CM)	+= cm_init.o

arch/mips/cpu/cm_init.S

@@ -0,0 +1,45 @@
+/*
+ * MIPS Coherence Manager (CM) Initialisation
+ *
+ * Copyright (c) 2016 Imagination Technologies Ltd.
+ *
+ * SPDX-License-Identifier:	GPL-2.0+
+ */
+
+#include <asm/addrspace.h>
+#include <asm/asm.h>
+#include <asm/cm.h>
+#include <asm/mipsregs.h>
+#include <asm/regdef.h>
+
+LEAF(mips_cm_map)
+	/* Config3 must exist for a CM to be present */
+	mfc0		t0, CP0_CONFIG, 1
+	bgez		t0, 2f
+	mfc0		t0, CP0_CONFIG, 2
+	bgez		t0, 2f
+
+	/* Check Config3.CMGCR to determine CM presence */
+	mfc0		t0, CP0_CONFIG, 3
+	and		t0, t0, MIPS_CONF3_CMGCR
+	beqz		t0, 2f
+
+	/* Find the current physical GCR base address */
+1:	MFC0		t0, CP0_CMGCRBASE
+	PTR_SLL		t0, t0, 4
+
+	/* If the GCRs are where we want, we're done */
+	PTR_LI		t1, CONFIG_MIPS_CM_BASE
+	beq		t0, t1, 2f
+
+	/* Move the GCRs to our configured base address */
+	PTR_LI		t2, CKSEG1
+	PTR_ADDU	t0, t0, t2
+	sw		zero, GCR_BASE_UPPER(t0)
+	sw		t1, GCR_BASE(t0)
+
+	/* Re-check the GCR base */
+	b		1b
+
+2:	jr		ra
+	END(mips_cm_map)

arch/mips/cpu/start.S

@@ -141,6 +141,12 @@ reset:
 1:
 	PTR_L	gp, 0(ra)
 
+#ifdef CONFIG_MIPS_CM
+	PTR_LA	t9, mips_cm_map
+	jalr	t9
+	 nop
+#endif
+
 #ifndef CONFIG_SKIP_LOWLEVEL_INIT
 # ifdef CONFIG_SYS_MIPS_CACHE_INIT_RAM_LOAD
 	/* Initialize any external memory */

arch/mips/include/asm/cm.h

@@ -0,0 +1,19 @@
+/*
+ * MIPS Coherence Manager (CM) Register Definitions
+ *
+ * Copyright (c) 2016 Imagination Technologies Ltd.
+ *
+ * SPDX-License-Identifier:	GPL-2.0+
+ */
+#ifndef __MIPS_ASM_CM_H__
+#define __MIPS_ASM_CM_H__
+
+/* Global Control Register (GCR) offsets */
+#define GCR_BASE			0x0008
+#define GCR_BASE_UPPER			0x000c
+#define GCR_REV				0x0030
+
+/* GCR_REV CM versions */
+#define GCR_REV_CM3			0x0800
+
+#endif /* __MIPS_ASM_CM_H__ */