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MIPS: Add LLB bit and related feature for the Config 5 CP0 register

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The LLBIT (bit 4) in the Config5 CP0 register indicates the software
availability of the Load-Linked bit. This bit is only set by hardware
and it has the following meaning:

0: LLB functionality is not supported
1: LLB functionality is supported. The following feature are also
supported:

- ERETNC instruction. Similar to ERET but it does not clear the LLB
bit in the LLAddr register.
- CP0 LLAddr/LLB bit must be set
- LLbit is software accessible through the LLAddr[0]

This will be used later on to emulate R2 LL/SC instructions.

Signed-off-by: Markos Chandras <markos.chandras@imgtec.com>
This commit is contained in:
Markos Chandras 2014-12-02 09:46:19 +00:00
parent 28d6f93d20
commit 5aed9da128
4 changed files with 7 additions and 0 deletions
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3
arch/mips/include/asm/cpu-features.h
View File

@ -38,6 +38,9 @@
#ifndef cpu_has_maar
#define cpu_has_maar (cpu_data[0].options & MIPS_CPU_MAAR)
#endif
#ifndef cpu_has_rw_llb
#define cpu_has_rw_llb (cpu_data[0].options & MIPS_CPU_RW_LLB)
#endif
/*
* For the moment we don't consider R6000 and R8000 so we can assume that

1
arch/mips/include/asm/cpu.h
View File

@ -376,6 +376,7 @@ enum cpu_type_enum {
#define MIPS_CPU_RIXIEX 0x200000000ull /* CPU has unique exception codes for {Read, Execute}-Inhibit exceptions */
#define MIPS_CPU_MAAR 0x400000000ull /* MAAR(I) registers are present */
#define MIPS_CPU_FRE 0x800000000ull /* FRE & UFE bits implemented */
#define MIPS_CPU_RW_LLB 0x1000000000ull /* LLADDR/LLB writes are allowed */
/*
* CPU ASE encodings

1
arch/mips/include/asm/mipsregs.h
View File

@ -653,6 +653,7 @@
#define MIPS_CONF5_NF (_ULCAST_(1) << 0)
#define MIPS_CONF5_UFR (_ULCAST_(1) << 2)
#define MIPS_CONF5_MRP (_ULCAST_(1) << 3)
#define MIPS_CONF5_LLB (_ULCAST_(1) << 4)
#define MIPS_CONF5_MVH (_ULCAST_(1) << 5)
#define MIPS_CONF5_FRE (_ULCAST_(1) << 8)
#define MIPS_CONF5_UFE (_ULCAST_(1) << 9)

2
arch/mips/kernel/cpu-probe.c
View File

@ -514,6 +514,8 @@ static inline unsigned int decode_config5(struct cpuinfo_mips *c)
c->options |= MIPS_CPU_EVA;
if (config5 & MIPS_CONF5_MRP)
c->options |= MIPS_CPU_MAAR;
if (config5 & MIPS_CONF5_LLB)
c->options |= MIPS_CPU_RW_LLB;
return config5 & MIPS_CONF_M;
}