[PATCH v3 06/12] sh: add support for J-Core J2 processor

[Rich Felker <dalias@libc.org>]

At the CPU/ISA level, the J2 is compatible with SH-2, and thus the
changes to add J2 support build on existing SH-2 support. However, J2
does not duplicate the memory-mapped SH-2 features like the cache
interface. Instead, the cache interfaces is described in the device
tree, and new code is added to be able to access the flat device tree
at early boot before it is unflattened.

Support is also added for receiving interrupts on trap numbers in the
range 16 to 31, since the J-Core aic1 interrupt controller generates
these traps. This range was unused but nominally for hardware
exceptions on SH-2, and a few values in this range were used for
exceptions on SH-2A, but SH-2A has its own version of the relevant
code.

No individual cpu subtypes are added for J2 since the intent moving
forward is to represent SoCs with device tree rather than as
hard-coded subtypes in the kernel. The CPU_SUBTYPE_J2 Kconfig item
exists only to fit into the existing cpu selection mechanism until it
is overhauled.

Signed-off-by: Rich Felker <dalias@libc.org>
---

Aside from adding commit message, this version of patch #6 in the
series only makes minor changes: spelling out SEI's name in a
copyright comment, and moving one asm insn that was placed on the
wrong side of an #ifdef (harmless but wrong).

 arch/sh/Kconfig                 |  8 ++++++
 arch/sh/Makefile                |  1 +
 arch/sh/include/asm/processor.h |  2 +-
 arch/sh/kernel/cpu/init.c       |  2 +-
 arch/sh/kernel/cpu/proc.c       |  1 +
 arch/sh/kernel/cpu/sh2/entry.S  |  5 ++++
 arch/sh/kernel/cpu/sh2/probe.c  | 34 +++++++++++++++++++++++-
 arch/sh/mm/Makefile             |  3 ++-
 arch/sh/mm/cache-j2.c           | 58 +++++++++++++++++++++++++++++++++++++++++
 arch/sh/mm/cache.c              |  6 ++++-
 10 files changed, 115 insertions(+), 5 deletions(-)
 create mode 100644 arch/sh/mm/cache-j2.c

diff --git a/arch/sh/Kconfig b/arch/sh/Kconfig
index 4fa5894..efb0af4 100644
--- a/arch/sh/Kconfig
+++ b/arch/sh/Kconfig
@@ -182,6 +182,10 @@ config CPU_SH2A
 	select CPU_SH2
 	select UNCACHED_MAPPING
 
+config CPU_J2
+	bool
+	select CPU_SH2
+
 config CPU_SH3
 	bool
 	select CPU_HAS_INTEVT
@@ -248,6 +252,10 @@ config CPU_SUBTYPE_SH7619
 	select CPU_SH2
 	select SYS_SUPPORTS_SH_CMT
 
+config CPU_SUBTYPE_J2
+	bool "Support J2 processor"
+	select CPU_J2
+
 # SH-2A Processor Support
 
 config CPU_SUBTYPE_SH7201
diff --git a/arch/sh/Makefile b/arch/sh/Makefile
index 3b2c8b4..0047666 100644
--- a/arch/sh/Makefile
+++ b/arch/sh/Makefile
@@ -31,6 +31,7 @@ isa-y					:= $(isa-y)-up
 endif
 
 cflags-$(CONFIG_CPU_SH2)		:= $(call cc-option,-m2,)
+cflags-$(CONFIG_CPU_J2)			:= $(call cc-option,-mj2,)
 cflags-$(CONFIG_CPU_SH2A)		+= $(call cc-option,-m2a,) \
 					   $(call cc-option,-m2a-nofpu,) \
 					   $(call cc-option,-m4-nofpu,)
diff --git a/arch/sh/include/asm/processor.h b/arch/sh/include/asm/processor.h
index 1506897..f9a0994 100644
--- a/arch/sh/include/asm/processor.h
+++ b/arch/sh/include/asm/processor.h
@@ -15,7 +15,7 @@
  */
 enum cpu_type {
 	/* SH-2 types */
-	CPU_SH7619,
+	CPU_SH7619, CPU_J2,
 
 	/* SH-2A types */
 	CPU_SH7201, CPU_SH7203, CPU_SH7206, CPU_SH7263, CPU_SH7264, CPU_SH7269,
diff --git a/arch/sh/kernel/cpu/init.c b/arch/sh/kernel/cpu/init.c
index bfd9e27..c8b3be1 100644
--- a/arch/sh/kernel/cpu/init.c
+++ b/arch/sh/kernel/cpu/init.c
@@ -106,7 +106,7 @@ void __attribute__ ((weak)) l2_cache_init(void)
 /*
  * Generic first-level cache init
  */
-#ifdef CONFIG_SUPERH32
+#if defined(CONFIG_SUPERH32) && !defined(CONFIG_CPU_J2)
 static void cache_init(void)
 {
 	unsigned long ccr, flags;
diff --git a/arch/sh/kernel/cpu/proc.c b/arch/sh/kernel/cpu/proc.c
index 9e6624c..4df4b28 100644
--- a/arch/sh/kernel/cpu/proc.c
+++ b/arch/sh/kernel/cpu/proc.c
@@ -27,6 +27,7 @@ static const char *cpu_name[] = {
 	[CPU_MXG]	= "MX-G",	[CPU_SH7723]	= "SH7723",
 	[CPU_SH7366]	= "SH7366",	[CPU_SH7724]	= "SH7724",
 	[CPU_SH7372]	= "SH7372",	[CPU_SH7734]	= "SH7734",
+	[CPU_J2]	= "J2",
 	[CPU_SH_NONE]	= "Unknown"
 };
 
diff --git a/arch/sh/kernel/cpu/sh2/entry.S b/arch/sh/kernel/cpu/sh2/entry.S
index a150595..16bde0e 100644
--- a/arch/sh/kernel/cpu/sh2/entry.S
+++ b/arch/sh/kernel/cpu/sh2/entry.S
@@ -147,6 +147,11 @@ ENTRY(exception_handler)
 	mov	#31,r8
 	cmp/hs	r8,r9
 	bt	trap_entry	! 64 > vec >= 31  is trap
+#ifdef CONFIG_CPU_J2
+	mov	#16,r8
+	cmp/hs	r8,r9
+	bt	interrupt_entry	! 31 > vec >= 16 is interrupt
+#endif
 
 	mov.l	4f,r8
 	mov	r9,r4
diff --git a/arch/sh/kernel/cpu/sh2/probe.c b/arch/sh/kernel/cpu/sh2/probe.c
index 6c687ae..3dd8187 100644
--- a/arch/sh/kernel/cpu/sh2/probe.c
+++ b/arch/sh/kernel/cpu/sh2/probe.c
@@ -10,10 +10,27 @@
  * for more details.
  */
 #include <linux/init.h>
+#include <linux/of_fdt.h>
+#include <linux/smp.h>
+#include <linux/io.h>
 #include <asm/processor.h>
 #include <asm/cache.h>
 
-void cpu_probe(void)
+#if defined(CONFIG_CPU_J2)
+extern u32 j2_ccr_base;
+static int __init scan_cache(unsigned long node, const char *uname,
+			     int depth, void *data)
+{
+	if (!of_flat_dt_is_compatible(node, "jcore,cache"))
+		return 0;
+
+	j2_ccr_base = of_flat_dt_translate_address(node);
+
+	return 1;
+}
+#endif
+
+void __ref cpu_probe(void)
 {
 #if defined(CONFIG_CPU_SUBTYPE_SH7619)
 	boot_cpu_data.type			= CPU_SH7619;
@@ -24,10 +41,25 @@ void cpu_probe(void)
 	boot_cpu_data.dcache.linesz		= L1_CACHE_BYTES;
 	boot_cpu_data.dcache.flags		= 0;
 #endif
+
+#if defined(CONFIG_CPU_J2)
+	unsigned cpu = hard_smp_processor_id();
+	if (cpu == 0) of_scan_flat_dt(scan_cache, NULL);
+	if (j2_ccr_base) __raw_writel(0x80000303, j2_ccr_base + 4*cpu);
+	if (cpu != 0) return;
+	boot_cpu_data.type			= CPU_J2;
+	/* FIXME: cache properties should come from device tree. */
+	boot_cpu_data.dcache.ways		= 1;
+	boot_cpu_data.dcache.sets		= 256;
+	boot_cpu_data.dcache.entry_shift	= 5;
+	boot_cpu_data.dcache.linesz		= 32;
+	boot_cpu_data.dcache.flags		= 0;
+#else
 	/*
 	 * SH-2 doesn't have separate caches
 	 */
 	boot_cpu_data.dcache.flags |= SH_CACHE_COMBINED;
+#endif
 	boot_cpu_data.icache = boot_cpu_data.dcache;
 	boot_cpu_data.family = CPU_FAMILY_SH2;
 }
diff --git a/arch/sh/mm/Makefile b/arch/sh/mm/Makefile
index cee6b99..92c3bd9 100644
--- a/arch/sh/mm/Makefile
+++ b/arch/sh/mm/Makefile
@@ -4,7 +4,8 @@
 
 obj-y			:= alignment.o cache.o init.o consistent.o mmap.o
 
-cacheops-$(CONFIG_CPU_SH2)		:= cache-sh2.o
+cacheops-$(CONFIG_CPU_J2)		:= cache-j2.o
+cacheops-$(CONFIG_CPU_SUBTYPE_SH7619)	:= cache-sh2.o
 cacheops-$(CONFIG_CPU_SH2A)		:= cache-sh2a.o
 cacheops-$(CONFIG_CPU_SH3)		:= cache-sh3.o
 cacheops-$(CONFIG_CPU_SH4)		:= cache-sh4.o flush-sh4.o
diff --git a/arch/sh/mm/cache-j2.c b/arch/sh/mm/cache-j2.c
new file mode 100644
index 0000000..11eb8d9
--- /dev/null
+++ b/arch/sh/mm/cache-j2.c
@@ -0,0 +1,58 @@
+/*
+ * arch/sh/mm/cache-j2.c
+ *
+ * Copyright (C) 2015-2016 Smart Energy Instruments, Inc.
+ *
+ * Released under the terms of the GNU GPL v2.0.
+ */
+
+#include <linux/init.h>
+#include <linux/mm.h>
+#include <linux/cpumask.h>
+
+#include <asm/cache.h>
+#include <asm/addrspace.h>
+#include <asm/processor.h>
+#include <asm/cacheflush.h>
+#include <asm/io.h>
+
+u32 j2_ccr_base;
+
+static void j2_flush_icache(void *args)
+{
+	unsigned cpu;
+	for_each_possible_cpu(cpu)
+		__raw_writel(0x80000103, j2_ccr_base + 4*cpu);
+}
+
+static void j2_flush_dcache(void *args)
+{
+	unsigned cpu;
+	for_each_possible_cpu(cpu)
+		__raw_writel(0x80000203, j2_ccr_base + 4*cpu);
+}
+
+static void j2_flush_both(void *args)
+{
+	unsigned cpu;
+	for_each_possible_cpu(cpu)
+		__raw_writel(0x80000303, j2_ccr_base + 4*cpu);
+}
+
+void __init j2_cache_init(void)
+{
+	if (!j2_ccr_base)
+		return;
+
+	local_flush_cache_all = j2_flush_both;
+	local_flush_cache_mm = j2_flush_both;
+	local_flush_cache_dup_mm = j2_flush_both;
+	local_flush_cache_page = j2_flush_both;
+	local_flush_cache_range = j2_flush_both;
+	local_flush_dcache_page = j2_flush_dcache;
+	local_flush_icache_range = j2_flush_icache;
+	local_flush_icache_page = j2_flush_icache;
+	local_flush_cache_sigtramp = j2_flush_icache;
+
+	pr_info("Initial J2 CCR is %.8x\n", __raw_readl(j2_ccr_base));
+}
diff --git a/arch/sh/mm/cache.c b/arch/sh/mm/cache.c
index 776d664..70cc52f 100644
--- a/arch/sh/mm/cache.c
+++ b/arch/sh/mm/cache.c
@@ -309,7 +309,11 @@ void __init cpu_cache_init(void)
 	if (unlikely(cache_disabled))
 		goto skip;
 
-	if (boot_cpu_data.family == CPU_FAMILY_SH2) {
+	if (boot_cpu_data.type == CPU_J2) {
+		extern void __weak j2_cache_init(void);
+
+		j2_cache_init();
+	} else if (boot_cpu_data.family == CPU_FAMILY_SH2) {
 		extern void __weak sh2_cache_init(void);
 
 		sh2_cache_init();
-- 
2.8.1