[MIPS] Fix configuration of R2 CPU features and multithreading.

Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

arch/mips/Kconfig

@@ -308,6 +308,7 @@ config MIPS_ATLAS
 	select SYS_SUPPORTS_64BIT_KERNEL
 	select SYS_SUPPORTS_BIG_ENDIAN
 	select SYS_SUPPORTS_LITTLE_ENDIAN
+	select SYS_SUPPORTS_MULTITHREADING if EXPERIMENTAL
 	help
 	  This enables support for the MIPS Technologies Atlas evaluation
 	  board.
@@ -336,6 +337,7 @@ config MIPS_MALTA
 	select SYS_SUPPORTS_64BIT_KERNEL
 	select SYS_SUPPORTS_BIG_ENDIAN
 	select SYS_SUPPORTS_LITTLE_ENDIAN
+	select SYS_SUPPORTS_MULTITHREADING
 	help
 	  This enables support for the MIPS Technologies Malta evaluation
 	  board.
@@ -1495,34 +1497,57 @@ config SIBYTE_DMA_PAGEOPS
 config CPU_HAS_PREFETCH
 	bool
 
-config MIPS_MT
-	bool "Enable MIPS MT"
-	depends on CPU_MIPS32_R2
-	#depends on CPU_MIPS64_R2		# later ...
-
 choice
 	prompt "MIPS MT options"
-	depends on MIPS_MT
+
+config MIPS_MT_DISABLED
+	bool "Disable multithreading support."
+	help
+	  Use this option if your workload can't take advantage of
+	  MIPS hardware multithreading support.  On systems that don't have
+	  the option of an MT-enabled processor this option will be the only
+	  option in this menu.
 
 config MIPS_MT_SMTC
 	bool "SMTC: Use all TCs on all VPEs for SMP"
+	depends on CPU_MIPS32_R2
+	#depends on CPU_MIPS64_R2		# once there is hardware ...
+	depends on SYS_SUPPORTS_MULTITHREADING
 	select CPU_MIPSR2_IRQ_VI
 	select CPU_MIPSR2_SRS
+	select MIPS_MT
 	select SMP
+	help
+	  This is a kernel model which is known a SMTC or lately has been
+	  marketesed into SMVP.
 
 config MIPS_MT_SMP
 	bool "Use 1 TC on each available VPE for SMP"
+	depends on SYS_SUPPORTS_MULTITHREADING
+	select CPU_MIPSR2_IRQ_VI
+	select CPU_MIPSR2_SRS
+	select MIPS_MT
 	select SMP
+	help
+	  This is a kernel model which is also known a VSMP or lately
+	  has been marketesed into SMVP.
 
 config MIPS_VPE_LOADER
 	bool "VPE loader support."
-	depends on MIPS_MT
+	depends on SYS_SUPPORTS_MULTITHREADING
+	select MIPS_MT
 	help
 	  Includes a loader for loading an elf relocatable object
 	  onto another VPE and running it.
 
 endchoice
 
+config MIPS_MT
+	bool
+
+config SYS_SUPPORTS_MULTITHREADING
+	bool
+
 config MIPS_MT_FPAFF
 	bool "Dynamic FPU affinity for FP-intensive threads"
 	depends on MIPS_MT
@@ -1579,32 +1604,23 @@ config CPU_HAS_LLSC
 config CPU_HAS_WB
 	bool
 
+#
+# Vectored interrupt mode is an R2 feature
+#
 config CPU_MIPSR2_IRQ_VI
-	bool "Vectored interrupt mode"
-	depends on CPU_MIPSR2
-	help
-	   Vectored interrupt mode allowing faster dispatching of interrupts.
-	   The board support code needs to be written to take advantage of this
-	   mode.  Compatibility code is included to allow the kernel to run on
-	   a CPU that does not support vectored interrupts.  It's safe to
-	   say Y here.
+	bool
 
+#
+# Extended interrupt mode is an R2 feature
+#
 config CPU_MIPSR2_IRQ_EI
-	bool "External interrupt controller mode"
-	depends on CPU_MIPSR2
-	help
-	   Extended interrupt mode takes advantage of an external interrupt
-	   controller to allow fast dispatching from many possible interrupt
-	   sources. Say N unless you know that external interrupt support is
-	   required.
+	bool
 
+#
+# Shadow registers are an R2 feature
+#
 config CPU_MIPSR2_SRS
-	bool "Make shadow set registers available for interrupt handlers"
-	depends on CPU_MIPSR2_IRQ_VI || CPU_MIPSR2_IRQ_EI
-	help
-	   Allow the kernel to use shadow register sets for fast interrupts.
-	   Interrupt handlers must be specially written to use shadow sets.
-	   Say N unless you know that shadow register set upport is needed.
+	bool
 
 config CPU_HAS_SYNC
 	bool

arch/mips/kernel/traps.c

@@ -1050,7 +1050,7 @@ void *set_except_vector(int n, void *addr)
 	return (void *)old_handler;
 }
 
-#ifdef CONFIG_CPU_MIPSR2
+#ifdef CONFIG_CPU_MIPSR2_SRS
 /*
  * MIPSR2 shadow register set allocation
  * FIXME: SMP...
@@ -1069,11 +1069,9 @@ static struct shadow_registers {
 
 static void mips_srs_init(void)
 {
-#ifdef CONFIG_CPU_MIPSR2_SRS
 	shadow_registers.sr_supported = ((read_c0_srsctl() >> 26) & 0x0f) + 1;
 	printk(KERN_INFO "%d MIPSR2 register sets available\n",
 	       shadow_registers.sr_supported);
-#endif
 	shadow_registers.sr_allocated = 1;	/* Set 0 used by kernel */
 }
 
@@ -1198,7 +1196,14 @@ void *set_vi_handler(int n, void *addr)
 {
 	return set_vi_srs_handler(n, addr, 0);
 }
-#endif
+
+#else
+
+static inline void mips_srs_init(void)
+{
+}
+
+#endif /* CONFIG_CPU_MIPSR2_SRS */
 
 /*
  * This is used by native signal handling
@@ -1388,9 +1393,7 @@ void __init trap_init(void)
 	else
 		ebase = CAC_BASE;
 
-#ifdef CONFIG_CPU_MIPSR2
 	mips_srs_init();
-#endif
 
 	per_cpu_trap_init();
 

include/asm-mips/cpu-features.h

@@ -187,19 +187,15 @@
 # endif
 #endif
 
-#ifdef CONFIG_CPU_MIPSR2
-# if defined(CONFIG_CPU_MIPSR2_IRQ_VI) && !defined(cpu_has_vint)
+#if defined(CONFIG_CPU_MIPSR2_IRQ_VI) && !defined(cpu_has_vint)
 # define cpu_has_vint		(cpu_data[0].options & MIPS_CPU_VINT)
-# else
+#elif !defined(cpu_has_vint)
 # define cpu_has_vint			0
-# endif
-# if defined(CONFIG_CPU_MIPSR2_IRQ_EI) && !defined(cpu_has_veic)
+#endif
+
+#if defined(CONFIG_CPU_MIPSR2_IRQ_EI) && !defined(cpu_has_veic)
 # define cpu_has_veic		(cpu_data[0].options & MIPS_CPU_VEIC)
-# else
-#  define cpu_has_veic			0
-# endif
-#else
-# define cpu_has_vint			0
+#elif !defined(cpu_has_veic)
 # define cpu_has_veic			0
 #endif