[PATCH 1/2] MIPS: Remove probe_tlb().

[PATCH 1/2] MIPS: Remove probe_tlb().

[David Daney]

The function probe_tlb() only does anything for processors that are
not PRID_COMP_LEGACY.  This is precisely the set of processors for
which decode_configs() is called to do identical tlbsize probing
calculations.  Therefore probe_tlb() is completely redundant and may
be removed.

Signed-off-by: David Daney <ddaney@caviumnetworks.com>
---
 arch/mips/mm/tlb-r4k.c |   31 -------------------------------
 1 files changed, 0 insertions(+), 31 deletions(-)

diff --git a/arch/mips/mm/tlb-r4k.c b/arch/mips/mm/tlb-r4k.c
index b61ad60..7de128a 100644
--- a/arch/mips/mm/tlb-r4k.c
+++ b/arch/mips/mm/tlb-r4k.c
@@ -447,34 +447,6 @@ out:
 	return ret;
 }
 
-static void __cpuinit probe_tlb(unsigned long config)
-{
-	struct cpuinfo_mips *c = &current_cpu_data;
-	unsigned int reg;
-
-	/*
-	 * If this isn't a MIPS32 / MIPS64 compliant CPU.  Config 1 register
-	 * is not supported, we assume R4k style.  Cpu probing already figured
-	 * out the number of tlb entries.
-	 */
-	if ((c->processor_id & 0xff0000) == PRID_COMP_LEGACY)
-		return;
-#ifdef CONFIG_MIPS_MT_SMTC
-	/*
-	 * If TLB is shared in SMTC system, total size already
-	 * has been calculated and written into cpu_data tlbsize
-	 */
-	if((smtc_status & SMTC_TLB_SHARED) == SMTC_TLB_SHARED)
-		return;
-#endif /* CONFIG_MIPS_MT_SMTC */
-
-	reg = read_c0_config1();
-	if (!((config >> 7) & 3))
-		panic("No TLB present");
-
-	c->tlbsize = ((reg >> 25) & 0x3f) + 1;
-}
-
 static int __cpuinitdata ntlb;
 static int __init set_ntlb(char *str)
 {
@@ -486,8 +458,6 @@ __setup("ntlb=", set_ntlb);
 
 void __cpuinit tlb_init(void)
 {
-	unsigned int config = read_c0_config();
-
 	/*
 	 * You should never change this register:
 	 *   - On R4600 1.7 the tlbp never hits for pages smaller than
@@ -495,7 +465,6 @@ void __cpuinit tlb_init(void)
 	 *   - The entire mm handling assumes the c0_pagemask register to
 	 *     be set to fixed-size pages.
 	 */
-	probe_tlb(config);
 	write_c0_pagemask(PM_DEFAULT_MASK);
 #ifndef CONFIG_MAPPED_KERNEL
 	write_c0_wired(0);
-- 
1.6.0.6

[PATCH 2/2] MIPS: Decode c0_config4 for large TLBs.

[David Daney]

For processors that have more than 64 TLBs, we need to decode both
config1 and config4 to determine the total number TLBs.

Signed-off-by: David Daney <ddaney@caviumnetworks.com>
---
 arch/mips/include/asm/mipsregs.h |    3 +++
 arch/mips/kernel/cpu-probe.c     |   14 ++++++++++++++
 2 files changed, 17 insertions(+), 0 deletions(-)

diff --git a/arch/mips/include/asm/mipsregs.h b/arch/mips/include/asm/mipsregs.h
index 5c192a0..298216e 100644
--- a/arch/mips/include/asm/mipsregs.h
+++ b/arch/mips/include/asm/mipsregs.h
@@ -564,6 +564,9 @@
 #define MIPS_CONF3_DSP		(_ULCAST_(1) << 10)
 #define MIPS_CONF3_ULRI		(_ULCAST_(1) << 13)
 
+#define MIPS_CONF4_MMUSIZEEXT	(_ULCAST_(255) << 0)
+#define MIPS_CONF4_MMUEXTDEF	(_ULCAST_(3) << 14)
+
 #define MIPS_CONF7_WII		(_ULCAST_(1) << 31)
 
 #define MIPS_CONF7_RPS		(_ULCAST_(1) << 2)
diff --git a/arch/mips/kernel/cpu-probe.c b/arch/mips/kernel/cpu-probe.c
index 80e202e..517c565 100644
--- a/arch/mips/kernel/cpu-probe.c
+++ b/arch/mips/kernel/cpu-probe.c
@@ -691,6 +691,18 @@ static inline unsigned int decode_config3(struct cpuinfo_mips *c)
 	return config3 & MIPS_CONF_M;
 }
 
+static inline unsigned int decode_config4(struct cpuinfo_mips *c)
+{
+	unsigned int config4;
+
+	config4 = read_c0_config4();
+
+	if ((config4 & MIPS_CONF4_MMUEXTDEF) == 0x4000 && cpu_has_tlb)
+		c->tlbsize += (config4 & MIPS_CONF4_MMUSIZEEXT) * 0x40;
+
+	return config4 & MIPS_CONF_M;
+}
+
 static void __cpuinit decode_configs(struct cpuinfo_mips *c)
 {
 	int ok;
@@ -709,6 +721,8 @@ static void __cpuinit decode_configs(struct cpuinfo_mips *c)
 		ok = decode_config2(c);
 	if (ok)
 		ok = decode_config3(c);
+	if (ok)
+		ok = decode_config4(c);
 
 	mips_probe_watch_registers(c);
 }
-- 
1.6.0.6

Re: [PATCH 1/2] MIPS: Remove probe_tlb().

[Ralf Baechle]

On Fri, Jan 22, 2010 at 02:41:14PM -0800, David Daney wrote:

> The function probe_tlb() only does anything for processors that are
> not PRID_COMP_LEGACY.  This is precisely the set of processors for
> which decode_configs() is called to do identical tlbsize probing
> calculations.  Therefore probe_tlb() is completely redundant and may
> be removed.
> 
> Signed-off-by: David Daney <ddaney@caviumnetworks.com>

Queued for 2.6.34.  Nice cleanup - it also gets rid of another SMTC
dependency.

Thanks,

  Ralf