Tegra: Configure L2 cache control reg properly.

Without this change, kernel fails at calling function cache_clean_flush
during kernel early boot.

Aprocryphally, intended for T114 only, so I check for a T114 SoC.
Works (i.e. dalmore 3.8 kernel now starts printing to console).

Signed-off-by: Tom Warren <twarren@nvidia.com>

arch/arm/cpu/tegra-common/Makefile

@@ -28,7 +28,7 @@ include $(TOPDIR)/config.mk
 LIB	= $(obj)libcputegra-common.o
 
 SOBJS += lowlevel_init.o
-COBJS-y	+= ap.o board.o sys_info.o timer.o clock.o
+COBJS-y	+= ap.o board.o sys_info.o timer.o clock.o cache.o
 
 SRCS	:= $(SOBJS:.o=.S) $(COBJS-y:.o=.c)
 OBJS	:= $(addprefix $(obj),$(SOBJS) $(COBJS-y))

arch/arm/cpu/tegra-common/ap.c

@@ -139,11 +139,6 @@ void s_init(void)
 
 	enable_scu();
 
-	/* enable SMP mode and FW for CPU0, by writing to Auxiliary Ctl reg */
-	asm volatile(
-		"mrc	p15, 0, r0, c1, c0, 1\n"
-		"orr	r0, r0, #0x41\n"
-		"mcr	p15, 0, r0, c1, c0, 1\n");
-
-	/* FIXME: should have SoC's L2 disabled too? */
+	/* init the cache */
+	config_cache();
 }

arch/arm/cpu/tegra-common/cache.c

@@ -0,0 +1,48 @@
+/*
+ * Copyright (c) 2013, NVIDIA CORPORATION.  All rights reserved.
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms and conditions of the GNU General Public License,
+ * version 2, as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
+ * more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+/* Tegra cache routines */
+
+#include <common.h>
+#include <asm/io.h>
+#include <asm/arch-tegra/ap.h>
+#include <asm/arch/gp_padctrl.h>
+
+void config_cache(void)
+{
+	struct apb_misc_gp_ctlr *gp =
+		(struct apb_misc_gp_ctlr *)NV_PA_APB_MISC_GP_BASE;
+	u32 reg = 0;
+
+	/* enable SMP mode and FW for CPU0, by writing to Auxiliary Ctl reg */
+	asm volatile(
+		"mrc p15, 0, r0, c1, c0, 1\n"
+		"orr r0, r0, #0x41\n"
+		"mcr p15, 0, r0, c1, c0, 1\n");
+
+	/* Currently, only T114 needs this L2 cache change to boot Linux */
+	reg = (readl(&gp->hidrev) & HIDREV_CHIPID_MASK);
+	if (reg != (CHIPID_TEGRA114 << HIDREV_CHIPID_SHIFT))
+		return;
+	/*
+	 * Systems with an architectural L2 cache must not use the PL310.
+	 * Config L2CTLR here for a data RAM latency of 3 cycles.
+	 */
+	asm("mrc p15, 1, %0, c9, c0, 2" : : "r" (reg));
+	reg &= ~7;
+	reg |= 2;
+	asm("mcr p15, 1, %0, c9, c0, 2" : : "r" (reg));
+}

arch/arm/include/asm/arch-tegra/ap.h

@@ -64,3 +64,4 @@ extern void _start(void);
  * @return	SOC type - see TEGRA_SOC...
  */
 int tegra_get_chip_type(void);
+void config_cache(void);