MIPS: MT: Remove SMTC support

Nobody is maintaining SMTC anymore and there also seems to be no userbase.
Which is a pity - the SMTC technology primarily developed by Kevin D.
Kissell <kevink@paralogos.com> is an ingenious demonstration for the MT
ASE's power and elegance.

Based on Markos Chandras <Markos.Chandras@imgtec.com> patch
https://patchwork.linux-mips.org/patch/6719/ which while very similar did
no longer apply cleanly when I tried to merge it plus some additional
post-SMTC cleanup - SMTC was a feature as tricky to remove as it was to
merge once upon a time.

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

arch/mips/mm/tlb-r4k.c

@@ -25,28 +25,6 @@
 
 extern void build_tlb_refill_handler(void);
 
-/* Atomicity and interruptability */
-#ifdef CONFIG_MIPS_MT_SMTC
-
-#include <asm/smtc.h>
-#include <asm/mipsmtregs.h>
-
-#define ENTER_CRITICAL(flags) \
-	{ \
-	unsigned int mvpflags; \
-	local_irq_save(flags);\
-	mvpflags = dvpe()
-#define EXIT_CRITICAL(flags) \
-	evpe(mvpflags); \
-	local_irq_restore(flags); \
-	}
-#else
-
-#define ENTER_CRITICAL(flags) local_irq_save(flags)
-#define EXIT_CRITICAL(flags) local_irq_restore(flags)
-
-#endif /* CONFIG_MIPS_MT_SMTC */
-
 /*
  * LOONGSON2/3 has a 4 entry itlb which is a subset of dtlb,
  * unfortunately, itlb is not totally transparent to software.
@@ -75,7 +53,7 @@ void local_flush_tlb_all(void)
 	unsigned long old_ctx;
 	int entry, ftlbhighset;
 
-	ENTER_CRITICAL(flags);
+	local_irq_save(flags);
 	/* Save old context and create impossible VPN2 value */
 	old_ctx = read_c0_entryhi();
 	write_c0_entrylo0(0);
@@ -112,7 +90,7 @@ void local_flush_tlb_all(void)
 	tlbw_use_hazard();
 	write_c0_entryhi(old_ctx);
 	flush_itlb();
-	EXIT_CRITICAL(flags);
+	local_irq_restore(flags);
 }
 EXPORT_SYMBOL(local_flush_tlb_all);
 
@@ -142,7 +120,7 @@ void local_flush_tlb_range(struct vm_area_struct *vma, unsigned long start,
 	if (cpu_context(cpu, mm) != 0) {
 		unsigned long size, flags;
 
-		ENTER_CRITICAL(flags);
+		local_irq_save(flags);
 		start = round_down(start, PAGE_SIZE << 1);
 		end = round_up(end, PAGE_SIZE << 1);
 		size = (end - start) >> (PAGE_SHIFT + 1);
@@ -176,7 +154,7 @@ void local_flush_tlb_range(struct vm_area_struct *vma, unsigned long start,
 			drop_mmu_context(mm, cpu);
 		}
 		flush_itlb();
-		EXIT_CRITICAL(flags);
+		local_irq_restore(flags);
 	}
 }
 
@@ -184,7 +162,7 @@ void local_flush_tlb_kernel_range(unsigned long start, unsigned long end)
 {
 	unsigned long size, flags;
 
-	ENTER_CRITICAL(flags);
+	local_irq_save(flags);
 	size = (end - start + (PAGE_SIZE - 1)) >> PAGE_SHIFT;
 	size = (size + 1) >> 1;
 	if (size <= (current_cpu_data.tlbsizeftlbsets ?
@@ -220,7 +198,7 @@ void local_flush_tlb_kernel_range(unsigned long start, unsigned long end)
 		local_flush_tlb_all();
 	}
 	flush_itlb();
-	EXIT_CRITICAL(flags);
+	local_irq_restore(flags);
 }
 
 void local_flush_tlb_page(struct vm_area_struct *vma, unsigned long page)
@@ -233,7 +211,7 @@ void local_flush_tlb_page(struct vm_area_struct *vma, unsigned long page)
 
 		newpid = cpu_asid(cpu, vma->vm_mm);
 		page &= (PAGE_MASK << 1);
-		ENTER_CRITICAL(flags);
+		local_irq_save(flags);
 		oldpid = read_c0_entryhi();
 		write_c0_entryhi(page | newpid);
 		mtc0_tlbw_hazard();
@@ -253,7 +231,7 @@ void local_flush_tlb_page(struct vm_area_struct *vma, unsigned long page)
 	finish:
 		write_c0_entryhi(oldpid);
 		flush_itlb_vm(vma);
-		EXIT_CRITICAL(flags);
+		local_irq_restore(flags);
 	}
 }
 
@@ -266,7 +244,7 @@ void local_flush_tlb_one(unsigned long page)
 	unsigned long flags;
 	int oldpid, idx;
 
-	ENTER_CRITICAL(flags);
+	local_irq_save(flags);
 	oldpid = read_c0_entryhi();
 	page &= (PAGE_MASK << 1);
 	write_c0_entryhi(page);
@@ -285,7 +263,7 @@ void local_flush_tlb_one(unsigned long page)
 	}
 	write_c0_entryhi(oldpid);
 	flush_itlb();
-	EXIT_CRITICAL(flags);
+	local_irq_restore(flags);
 }
 
 /*
@@ -308,7 +286,7 @@ void __update_tlb(struct vm_area_struct * vma, unsigned long address, pte_t pte)
 	if (current->active_mm != vma->vm_mm)
 		return;
 
-	ENTER_CRITICAL(flags);
+	local_irq_save(flags);
 
 	pid = read_c0_entryhi() & ASID_MASK;
 	address &= (PAGE_MASK << 1);
@@ -358,7 +336,7 @@ void __update_tlb(struct vm_area_struct * vma, unsigned long address, pte_t pte)
 	}
 	tlbw_use_hazard();
 	flush_itlb_vm(vma);
-	EXIT_CRITICAL(flags);
+	local_irq_restore(flags);
 }
 
 void add_wired_entry(unsigned long entrylo0, unsigned long entrylo1,
@@ -369,7 +347,7 @@ void add_wired_entry(unsigned long entrylo0, unsigned long entrylo1,
 	unsigned long old_pagemask;
 	unsigned long old_ctx;
 
-	ENTER_CRITICAL(flags);
+	local_irq_save(flags);
 	/* Save old context and create impossible VPN2 value */
 	old_ctx = read_c0_entryhi();
 	old_pagemask = read_c0_pagemask();
@@ -389,7 +367,7 @@ void add_wired_entry(unsigned long entrylo0, unsigned long entrylo1,
 	tlbw_use_hazard();	/* What is the hazard here? */
 	write_c0_pagemask(old_pagemask);
 	local_flush_tlb_all();
-	EXIT_CRITICAL(flags);
+	local_irq_restore(flags);
 }
 
 #ifdef CONFIG_TRANSPARENT_HUGEPAGE
@@ -399,13 +377,13 @@ int __init has_transparent_hugepage(void)
 	unsigned int mask;
 	unsigned long flags;
 
-	ENTER_CRITICAL(flags);
+	local_irq_save(flags);
 	write_c0_pagemask(PM_HUGE_MASK);
 	back_to_back_c0_hazard();
 	mask = read_c0_pagemask();
 	write_c0_pagemask(PM_DEFAULT_MASK);
 
-	EXIT_CRITICAL(flags);
+	local_irq_restore(flags);
 
 	return mask == PM_HUGE_MASK;
 }