[PATCH] MIPS: Loongson: Add board_ebase_setup() support

[PATCH] MIPS: Loongson: Add board_ebase_setup() support

[Huacai Chen]

Old processors before Loongson-3A2000 have a 32bit ebase register and
have no WG bit, new processors since Loongson-3A2000 have a 64bit ebase
register and do have the WG bit. Unfortunately, Loongson processors
which have the WG bit are slightly different from MIPS R2. This makes
the generic ebase setup not suitable for every scenarios.

To make Loongson's kernel be more robust, we add a board_ebase_setup()
hook to ensure that CKSEG0 is always used for ebase. This is also useful
on platforms where BIOS doesn't initialise an appropriate ebase.

Signed-off-by: Huacai Chen <chenhc@lemote.com>
---
 arch/mips/kernel/cpu-probe.c       |  6 ++++--
 arch/mips/loongson64/common/init.c | 11 +++++++++++
 2 files changed, 15 insertions(+), 2 deletions(-)

diff --git a/arch/mips/kernel/cpu-probe.c b/arch/mips/kernel/cpu-probe.c
index 671bc6f..7312a0d 100644
--- a/arch/mips/kernel/cpu-probe.c
+++ b/arch/mips/kernel/cpu-probe.c
@@ -1923,7 +1923,8 @@ static inline void cpu_probe_loongson(struct cpuinfo_mips *c, unsigned int cpu)
 		}
 
 		decode_configs(c);
-		c->options |= MIPS_CPU_FTLB | MIPS_CPU_TLBINV | MIPS_CPU_LDPTE;
+		c->options |= MIPS_CPU_FTLB | MIPS_CPU_TLBINV |
+			      MIPS_CPU_LDPTE | MIPS_CPU_EBASE_WG;
 		c->writecombine = _CACHE_UNCACHED_ACCELERATED;
 		c->ases |= (MIPS_ASE_LOONGSON_MMI | MIPS_ASE_LOONGSON_CAM |
 			MIPS_ASE_LOONGSON_EXT | MIPS_ASE_LOONGSON_EXT2);
@@ -1934,7 +1935,8 @@ static inline void cpu_probe_loongson(struct cpuinfo_mips *c, unsigned int cpu)
 		set_elf_platform(cpu, "loongson3a");
 		set_isa(c, MIPS_CPU_ISA_M64R2);
 		decode_configs(c);
-		c->options |= MIPS_CPU_FTLB | MIPS_CPU_TLBINV | MIPS_CPU_LDPTE;
+		c->options |= MIPS_CPU_FTLB | MIPS_CPU_TLBINV |
+			      MIPS_CPU_LDPTE | MIPS_CPU_EBASE_WG;
 		c->writecombine = _CACHE_UNCACHED_ACCELERATED;
 		c->ases |= (MIPS_ASE_LOONGSON_MMI | MIPS_ASE_LOONGSON_CAM |
 			MIPS_ASE_LOONGSON_EXT | MIPS_ASE_LOONGSON_EXT2);
diff --git a/arch/mips/loongson64/common/init.c b/arch/mips/loongson64/common/init.c
index 912fe61..8e2047d 100644
--- a/arch/mips/loongson64/common/init.c
+++ b/arch/mips/loongson64/common/init.c
@@ -15,6 +15,16 @@
 /* Loongson CPU address windows config space base address */
 unsigned long __maybe_unused _loongson_addrwincfg_base;
 
+static void __init mips_ebase_setup(void)
+{
+	ebase = CKSEG0;
+
+	if (cpu_has_ebase_wg)
+		write_c0_ebase(ebase | MIPS_EBASE_WG);
+
+	write_c0_ebase(ebase);
+}
+
 static void __init mips_nmi_setup(void)
 {
 	void *base;
@@ -48,6 +58,7 @@ void __init prom_init(void)
 	/*init the uart base address */
 	prom_init_uart_base();
 	register_smp_ops(&loongson3_smp_ops);
+	board_ebase_setup = mips_ebase_setup;
 	board_nmi_handler_setup = mips_nmi_setup;
 }
 
-- 
2.7.0

Re: [PATCH] MIPS: Loongson: Add board_ebase_setup() support

[Jiaxun Yang]

在 2019/10/25 上午11:45, Huacai Chen 写道:
> Old processors before Loongson-3A2000 have a 32bit ebase register and
> have no WG bit, new processors since Loongson-3A2000 have a 64bit ebase
> register and do have the WG bit. Unfortunately, Loongson processors
> which have the WG bit are slightly different from MIPS R2. This makes
> the generic ebase setup not suitable for every scenarios.
> 
> To make Loongson's kernel be more robust, we add a board_ebase_setup()
> hook to ensure that CKSEG0 is always used for ebase. This is also useful
> on platforms where BIOS doesn't initialise an appropriate ebase.
> 
> Signed-off-by: Huacai Chen <chenhc@lemote.com>
Reviewed-by: Jiaxun Yang <jiaxun.yang@flygoat.com>
> ---
--
Jiaxun Yang