[PATCH v2] MIPS: R10000: Split R10000 definitions from R12000 and up

[PATCH v2] MIPS: R10000: Split R10000 definitions from R12000 and up

[Joshua Kinard]

From: Joshua Kinard <kumba@gentoo.org>

This patch splits the old R10000 definitions so that the R10000_LLSC_WAR can be
disabled and -mno-fix-r10000 passed to CFLAGS for systems running R12000 CPUs
and greater.  This allows the kernel to build without branch-likely
instructions, which are considered deprecated in current MIPS implementations.
 Only R10000 systems with R2.6 and lower CPUs require branch-likely to work
around a known hardware errata item.

Verified on both an SGI Onyx2 and an SGI Octane.

Signed-off-by: Joshua Kinard <kumba@gentoo.org>
---
 arch/mips/Kconfig                     |   20 ++++++++++++++++++--
 arch/mips/Makefile                    |    3 +++
 arch/mips/include/asm/cpu-type.h      |    2 ++
 arch/mips/include/asm/hazards.h       |    3 ++-
 arch/mips/include/asm/mach-ip27/war.h |    7 ++++++-
 arch/mips/include/asm/module.h        |    2 ++
 arch/mips/oprofile/Makefile           |    1 +
 arch/mips/oprofile/op_model_mipsxx.c  |    5 ++++-
 arch/mips/sgi-ip27/Platform           |   15 ++++++++-------
 arch/mips/sgi-ip32/Platform           |    2 ++
 drivers/video/fbdev/gbefb.c           |    2 +-
 11 files changed, 49 insertions(+), 13 deletions(-)

Only changed bit is catching a few missed spots where the R10K needed to be
differentiated from R12K and up.  I think I got them all this time.

This patch will conflict slightly with the R16000 patch in the
arch/mips/oprofile/op_model_mipsxx.c file.  Not much I can do about that.

linux-mips-split-r10k-family.patch
diff --git a/arch/mips/Kconfig b/arch/mips/Kconfig
index 73983e1..af4b282 100644
--- a/arch/mips/Kconfig
+++ b/arch/mips/Kconfig
@@ -551,6 +551,7 @@ config SGI_IP27
 	select HW_HAS_PCI
 	select NR_CPUS_DEFAULT_64
 	select SYS_HAS_CPU_R10000
+	select SYS_HAS_CPU_R12K_R14K_R16K
 	select SYS_SUPPORTS_64BIT_KERNEL
 	select SYS_SUPPORTS_BIG_ENDIAN
 	select SYS_SUPPORTS_NUMA
@@ -612,6 +613,7 @@ config SGI_IP32
 	select RM7000_CPU_SCACHE
 	select SYS_HAS_CPU_R5000
 	select SYS_HAS_CPU_R10000 if BROKEN
+	select SYS_HAS_CPU_R12K_R14K_R16K if BROKEN
 	select SYS_HAS_CPU_RM7000
 	select SYS_HAS_CPU_NEVADA
 	select SYS_SUPPORTS_64BIT_KERNEL
@@ -1456,7 +1458,18 @@ config CPU_R10000
 	select CPU_SUPPORTS_HIGHMEM
 	select CPU_SUPPORTS_HUGEPAGES
 	help
-	  MIPS Technologies R10000-series processors.
+	  MIPS Technologies R10000 processor.
+
+config CPU_R12K_R14K_R16K
+	bool "R12k/R14k/R16k"
+	depends on SYS_HAS_CPU_R12K_R14K_R16K
+	select CPU_HAS_PREFETCH
+	select CPU_SUPPORTS_32BIT_KERNEL
+	select CPU_SUPPORTS_64BIT_KERNEL
+	select CPU_SUPPORTS_HIGHMEM
+	select CPU_SUPPORTS_HUGEPAGES
+	help
+	  MIPS Technologies R12k/R14k/R16k-series processors.
 
 config CPU_RM7000
 	bool "RM7000"
@@ -1704,6 +1717,9 @@ config SYS_HAS_CPU_R8000
 config SYS_HAS_CPU_R10000
 	bool
 
+config SYS_HAS_CPU_R12K_R14K_R16K
+	bool
+
 config SYS_HAS_CPU_RM7000
 	bool
 
@@ -2283,7 +2299,7 @@ config NODES_SHIFT
 
 config HW_PERF_EVENTS
 	bool "Enable hardware performance counter support for perf events"
-	depends on PERF_EVENTS && OPROFILE=n && (CPU_MIPS32 || CPU_MIPS64 || CPU_R10000 || CPU_SB1 || CPU_CAVIUM_OCTEON || CPU_XLP)
+	depends on PERF_EVENTS && OPROFILE=n && (CPU_MIPS32 || CPU_MIPS64 || CPU_R10000 || CPU_R12K_R14K_R16K || CPU_SB1 || CPU_CAVIUM_OCTEON || CPU_XLP)
 	default y
 	help
 	  Enable hardware performance counter support for perf events. If
diff --git a/arch/mips/Makefile b/arch/mips/Makefile
index 37fce70..abccbb2 100644
--- a/arch/mips/Makefile
+++ b/arch/mips/Makefile
@@ -176,6 +176,9 @@ cflags-$(CONFIG_CPU_SB1)	+= $(call cc-option,-mno-mips3d)
 cflags-$(CONFIG_CPU_R8000)	+= -march=r8000 -Wa,--trap
 cflags-$(CONFIG_CPU_R10000)	+= $(call cc-option,-march=r10000,-march=r8000) \
 			-Wa,--trap
+cflags-$(CONFIG_CPU_R12K_R14K_R16K)	+= $(call cc-option,-march=r12000,-march=r8000) \
+			$(call cc-option,-mno-fix-r10000,) \
+			-Wa,--trap
 cflags-$(CONFIG_CPU_CAVIUM_OCTEON) += $(call cc-option,-march=octeon) -Wa,--trap
 ifeq (,$(findstring march=octeon, $(cflags-$(CONFIG_CPU_CAVIUM_OCTEON))))
 cflags-$(CONFIG_CPU_CAVIUM_OCTEON) += -Wa,-march=octeon
diff --git a/arch/mips/include/asm/cpu-type.h b/arch/mips/include/asm/cpu-type.h
index b4e2bd8..73c9f51 100644
--- a/arch/mips/include/asm/cpu-type.h
+++ b/arch/mips/include/asm/cpu-type.h
@@ -148,6 +148,8 @@ static inline int __pure __get_cpu_type(const int cpu_type)
 
 #ifdef CONFIG_SYS_HAS_CPU_R10000
 	case CPU_R10000:
+#endif
+#ifdef CONFIG_SYS_HAS_CPU_R12K_R14K_R16K
 	case CPU_R12000:
 	case CPU_R14000:
 #endif
diff --git a/arch/mips/include/asm/hazards.h b/arch/mips/include/asm/hazards.h
index e3ee92d..0b565e5 100644
--- a/arch/mips/include/asm/hazards.h
+++ b/arch/mips/include/asm/hazards.h
@@ -138,7 +138,8 @@ do {									\
 
 #elif defined(CONFIG_MIPS_ALCHEMY) || defined(CONFIG_CPU_CAVIUM_OCTEON) || \
 	defined(CONFIG_CPU_LOONGSON2) || defined(CONFIG_CPU_R10000) || \
-	defined(CONFIG_CPU_R5500) || defined(CONFIG_CPU_XLR)
+	defined(CONFIG_CPU_R12K_R14K_R16K) || defined(CONFIG_CPU_R5500) || \
+	defined(CONFIG_CPU_XLR)
 
 /*
  * R10000 rocks - all hazards handled in hardware, so this becomes a nobrainer.
diff --git a/arch/mips/include/asm/mach-ip27/war.h b/arch/mips/include/asm/mach-ip27/war.h
index 4ee0e4b..e901a81 100644
--- a/arch/mips/include/asm/mach-ip27/war.h
+++ b/arch/mips/include/asm/mach-ip27/war.h
@@ -18,7 +18,12 @@
 #define MIPS_CACHE_SYNC_WAR		0
 #define TX49XX_ICACHE_INDEX_INV_WAR	0
 #define ICACHE_REFILLS_WORKAROUND_WAR	0
-#define R10000_LLSC_WAR			1
 #define MIPS34K_MISSED_ITLB_WAR		0
 
+#ifdef CONFIG_CPU_R10000
+#define R10000_LLSC_WAR			1
+#else
+#define R10000_LLSC_WAR			0
+#endif
+
 #endif /* __ASM_MIPS_MACH_IP27_WAR_H */
diff --git a/arch/mips/include/asm/module.h b/arch/mips/include/asm/module.h
index 800fe57..394dee4 100644
--- a/arch/mips/include/asm/module.h
+++ b/arch/mips/include/asm/module.h
@@ -118,6 +118,8 @@ search_module_dbetables(unsigned long addr)
 #define MODULE_PROC_FAMILY "R8000 "
 #elif defined CONFIG_CPU_R10000
 #define MODULE_PROC_FAMILY "R10000 "
+#elif defined CONFIG_CPU_R12K_R14K_R16K
+#define MODULE_PROC_FAMILY "R12K/R14K/R16K "
 #elif defined CONFIG_CPU_RM7000
 #define MODULE_PROC_FAMILY "RM7000 "
 #elif defined CONFIG_CPU_SB1
diff --git a/arch/mips/oprofile/Makefile b/arch/mips/oprofile/Makefile
index 070afdb..050a44e 100644
--- a/arch/mips/oprofile/Makefile
+++ b/arch/mips/oprofile/Makefile
@@ -11,6 +11,7 @@ oprofile-y				:= $(DRIVER_OBJS) common.o backtrace.o
 oprofile-$(CONFIG_CPU_MIPS32)		+= op_model_mipsxx.o
 oprofile-$(CONFIG_CPU_MIPS64)		+= op_model_mipsxx.o
 oprofile-$(CONFIG_CPU_R10000)		+= op_model_mipsxx.o
+oprofile-$(CONFIG_CPU_R12K_R14K_R16K)	+= op_model_mipsxx.o
 oprofile-$(CONFIG_CPU_SB1)		+= op_model_mipsxx.o
 oprofile-$(CONFIG_CPU_XLR)		+= op_model_mipsxx.o
 oprofile-$(CONFIG_CPU_LOONGSON2)	+= op_model_loongson2.o
diff --git a/arch/mips/oprofile/op_model_mipsxx.c b/arch/mips/oprofile/op_model_mipsxx.c
index 01f721a..d3a2b94 100644
--- a/arch/mips/oprofile/op_model_mipsxx.c
+++ b/arch/mips/oprofile/op_model_mipsxx.c
@@ -407,10 +407,13 @@ static int __init mipsxx_init(void)
 		break;
 
 	case CPU_R12000:
-	case CPU_R14000:
 		op_model_mipsxx_ops.cpu_type = "mips/r12000";
 		break;
 
+	case CPU_R14000:
+		op_model_mipsxx_ops.cpu_type = "mips/r14000";
+		break;
+
 	case CPU_SB1:
 	case CPU_SB1A:
 		op_model_mipsxx_ops.cpu_type = "mips/sb1";
diff --git a/arch/mips/sgi-ip27/Platform b/arch/mips/sgi-ip27/Platform
index 1fb9c2e..4ad7060 100644
--- a/arch/mips/sgi-ip27/Platform
+++ b/arch/mips/sgi-ip27/Platform
@@ -6,14 +6,15 @@
 # be 16kb aligned or the handling of the current variable will break.
 #
 ifdef CONFIG_SGI_IP27
-platform-$(CONFIG_SGI_IP27)	+= sgi-ip27/
-cflags-$(CONFIG_SGI_IP27)	+= -I$(srctree)/arch/mips/include/asm/mach-ip27
+platform-$(CONFIG_SGI_IP27)		+= sgi-ip27/
+cflags-$(CONFIG_SGI_IP27)		+= -I$(srctree)/arch/mips/include/asm/mach-ip27
+cflags-$(CONFIG_CPU_R12K_R14K_R16K)	+= -mno-fix-r10000
 ifdef CONFIG_MAPPED_KERNEL
-load-$(CONFIG_SGI_IP27)		+= 0xc00000004001c000
-OBJCOPYFLAGS			:= --change-addresses=0x3fffffff80000000
-dataoffset-$(CONFIG_SGI_IP27)	+= 0x01000000
+load-$(CONFIG_SGI_IP27)			+= 0xc00000004001c000
+OBJCOPYFLAGS				:= --change-addresses=0x3fffffff80000000
+dataoffset-$(CONFIG_SGI_IP27)		+= 0x01000000
 else
-load-$(CONFIG_SGI_IP27)		+= 0xa80000000001c000
-OBJCOPYFLAGS			:= --change-addresses=0x57ffffff80000000
+load-$(CONFIG_SGI_IP27)			+= 0xa80000000001c000
+OBJCOPYFLAGS				:= --change-addresses=0x57ffffff80000000
 endif
 endif
diff --git a/arch/mips/sgi-ip32/Platform b/arch/mips/sgi-ip32/Platform
index 0fea556..5899305 100644
--- a/arch/mips/sgi-ip32/Platform
+++ b/arch/mips/sgi-ip32/Platform
@@ -8,4 +8,6 @@
 #
 platform-$(CONFIG_SGI_IP32)	+= sgi-ip32/
 cflags-$(CONFIG_SGI_IP32)	+= -I$(srctree)/arch/mips/include/asm/mach-ip32
+cflags-$(CONFIG_CPU_R10000)		+= -mr10k-cache-barrier=load-store
+cflags-$(CONFIG_CPU_R12K_R14K_R16K)	+= -mno-fix-r10000 -mr10k-cache-barrier=load-store
 load-$(CONFIG_SGI_IP32)		+= 0xffffffff80004000
diff --git a/drivers/video/fbdev/gbefb.c b/drivers/video/fbdev/gbefb.c
index 6d9ef39..c5dc991 100644
--- a/drivers/video/fbdev/gbefb.c
+++ b/drivers/video/fbdev/gbefb.c
@@ -47,7 +47,7 @@ struct gbefb_par {
 
 /* macro for fastest write-though access to the framebuffer */
 #ifdef CONFIG_MIPS
-#ifdef CONFIG_CPU_R10000
+#if defined(CONFIG_CPU_R10000) || defined(CONFIG_CPU_R12K_R14K_R16K)
 #define pgprot_fb(_prot) (((_prot) & (~_CACHE_MASK)) | _CACHE_UNCACHED_ACCELERATED)
 #else
 #define pgprot_fb(_prot) (((_prot) & (~_CACHE_MASK)) | _CACHE_CACHABLE_NO_WA)

Re: [PATCH v2] MIPS: R10000: Split R10000 definitions from R12000 and up

[Ralf Baechle]

On Wed, Jan 21, 2015 at 07:51:43AM -0500, Joshua Kinard wrote:

>  up
> Content-Type: text/plain; charset=utf-8
> 
> From: Joshua Kinard <kumba@gentoo.org>
> 
> This patch splits the old R10000 definitions so that the R10000_LLSC_WAR can be
> disabled and -mno-fix-r10000 passed to CFLAGS for systems running R12000 CPUs
> and greater.  This allows the kernel to build without branch-likely
> instructions, which are considered deprecated in current MIPS implementations.
>  Only R10000 systems with R2.6 and lower CPUs require branch-likely to work
> around a known hardware errata item.

The kernel doesn't use -mfix-r10000 rsp. -mno-fix-r10000 or any code that
would rely on the default setting for this option.  The kernel rather
opencodes all these atomic sequences in inline assembler.

Only platforms which are known to be equipped with R10000 v2.6 processors
enable R10000_LLSC_WAR and I've done so quite intentionally not just for
some CPU configuration but the entire platforms which at this time are IP27
and IP28.

Another mysterious question of course is why
arch/mips/include/asm/mach-pmcs-msp71xx/msp_regops.h caters for the case
where R10000_LLSC_WAR is enabled.  It won't be for that platform.

  Ralf

Re: [PATCH v2] MIPS: R10000: Split R10000 definitions from R12000 and up

[Joshua Kinard]

On 03/31/2015 08:17, Ralf Baechle wrote:
> On Wed, Jan 21, 2015 at 07:51:43AM -0500, Joshua Kinard wrote:
> 
>>  up
>> Content-Type: text/plain; charset=utf-8
>>
>> From: Joshua Kinard <kumba@gentoo.org>
>>
>> This patch splits the old R10000 definitions so that the R10000_LLSC_WAR can be
>> disabled and -mno-fix-r10000 passed to CFLAGS for systems running R12000 CPUs
>> and greater.  This allows the kernel to build without branch-likely
>> instructions, which are considered deprecated in current MIPS implementations.
>>  Only R10000 systems with R2.6 and lower CPUs require branch-likely to work
>> around a known hardware errata item.
> 
> The kernel doesn't use -mfix-r10000 rsp. -mno-fix-r10000 or any code that
> would rely on the default setting for this option.  The kernel rather
> opencodes all these atomic sequences in inline assembler.

True, though I added that on the off chance the compiler decides to emit its
own ll/sc pair somewhere and thus could use normal beq/beqz insns instead of
the branch-likely variants.  Couldn't hurt.


> Only platforms which are known to be equipped with R10000 v2.6 processors
> enable R10000_LLSC_WAR and I've done so quite intentionally not just for
> some CPU configuration but the entire platforms which at this time are IP27
> and IP28.

This allows one to override this on IP27 at least.  I've got both R12K and R14K
node boards, neither of which require the branch-likely workarounds, so it's
safe to disable the WAR there.  And although it's not in the tree yet, IP30
also benefits from this as well.  I am not sure how old the IP30 R10000 CPU
revs can go, so it might need the WAR in limited circumstances, too.  It also
sets things up to further separate R12K from R14K should any beneficial
enhancements be discovered in the future (or if I can ever figure out why R14K
seems weirder in some instances than R12K).

-- 
Joshua Kinard
Gentoo/MIPS
kumba@gentoo.org
4096R/D25D95E3 2011-03-28

"The past tempts us, the present confuses us, the future frightens us.  And our
lives slip away, moment by moment, lost in that vast, terrible in-between."

--Emperor Turhan, Centauri Republic

Re: [PATCH v2] MIPS: R10000: Split R10000 definitions from R12000 and up

[Tom Bogendoerfer]

On Wed, Apr 01, 2015 at 12:36:42AM -0400, Joshua Kinard wrote:
> also benefits from this as well.  I am not sure how old the IP30 R10000 CPU

ARCH: SGI-IP30
PROMLIB: ARC firmware Version 64 Revision 0
console [early0] enabled
CPU revision is: 00000927 (R10000)

Thomas.

-- 
Crap can work. Given enough thrust pigs will fly, but it's not necessarily a
good idea.                                                [ RFC1925, 2.3 ]