MIPS: Loongson-3: Introduce CONFIG_LOONGSON3_ENHANCEMENT
New Loongson 3 CPU (since Loongson-3A R2, as opposed to Loongson-3A R1,
Loongson-3B R1 and Loongson-3B R2) has many enhancements, such as FTLB,
L1-VCache, EI/DI/Wait/Prefetch instruction, DSP/DSPv2 ASE, User Local
register, Read-Inhibit/Execute-Inhibit, SFB (Store Fill Buffer), Fast
TLB refill support, etc.
This patch introduce a config option, CONFIG_LOONGSON3_ENHANCEMENT, to
enable those enhancements which are not probed at run time. If you want
a generic kernel to run on all Loongson 3 machines, please say 'N'
here. If you want a high-performance kernel to run on new Loongson 3
machines only, please say 'Y' here.
Some additional explanations:
1) SFB locates between core and L1 cache, it causes memory access out
of order, so writel/outl (and other similar functions) need a I/O
reorder barrier.
2) Loongson 3 has a bug that di instruction can not save the irqflag,
so arch_local_irq_save() is modified. Since CPU_MIPSR2 is selected
by CONFIG_LOONGSON3_ENHANCEMENT, generic kernel doesn't use ei/di
at all.
3) CPU_HAS_PREFETCH is selected by CONFIG_LOONGSON3_ENHANCEMENT, so
MIPS_CPU_PREFETCH (used by uasm) probing is also put in this patch.
Signed-off-by: Huacai Chen <chenhc@lemote.com>
Cc: Aurelien Jarno <aurelien@aurel32.net>
Cc: Steven J . Hill <sjhill@realitydiluted.com>
Cc: Fuxin Zhang <zhangfx@lemote.com>
Cc: Zhangjin Wu <wuzhangjin@gmail.com>
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/12755/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
diff --git a/arch/mips/Kconfig b/arch/mips/Kconfig
index adcc97e..d5c3621 100644
--- a/arch/mips/Kconfig
+++ b/arch/mips/Kconfig
@@ -1360,6 +1360,24 @@
The Loongson 3 processor implements the MIPS64R2 instruction
set with many extensions.
+config LOONGSON3_ENHANCEMENT
+ bool "New Loongson 3 CPU Enhancements"
+ default n
+ select CPU_MIPSR2
+ select CPU_HAS_PREFETCH
+ depends on CPU_LOONGSON3
+ help
+ New Loongson 3 CPU (since Loongson-3A R2, as opposed to Loongson-3A
+ R1, Loongson-3B R1 and Loongson-3B R2) has many enhancements, such as
+ FTLB, L1-VCache, EI/DI/Wait/Prefetch instruction, DSP/DSPv2 ASE, User
+ Local register, Read-Inhibit/Execute-Inhibit, SFB (Store Fill Buffer),
+ Fast TLB refill support, etc.
+
+ This option enable those enhancements which are not probed at run
+ time. If you want a generic kernel to run on all Loongson 3 machines,
+ please say 'N' here. If you want a high-performance kernel to run on
+ new Loongson 3 machines only, please say 'Y' here.
+
config CPU_LOONGSON2E
bool "Loongson 2E"
depends on SYS_HAS_CPU_LOONGSON2E
