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>

1 files changed, 5 insertions, 63 deletions

diff --git a/arch/mips/mm/init.c b/arch/mips/mm/init.c
index 4fc74c7..609a0cd 100644
--- a/arch/mips/mm/init.c
+++ b/arch/mips/mm/init.c
@@ -44,27 +44,6 @@
 #include <asm/tlb.h>
 #include <asm/fixmap.h>
 
-/* Atomicity and interruptability */
-#ifdef CONFIG_MIPS_MT_SMTC
-
-#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 */
-
 /*
  * We have up to 8 empty zeroed pages so we can map one of the right colour
  * when needed.	 This is necessary only on R4000 / R4400 SC and MC versions
@@ -100,20 +79,6 @@ void setup_zero_pages(void)
 	zero_page_mask = ((PAGE_SIZE << order) - 1) & PAGE_MASK;
 }
 
-#ifdef CONFIG_MIPS_MT_SMTC
-static pte_t *kmap_coherent_pte;
-static void __init kmap_coherent_init(void)
-{
-	unsigned long vaddr;
-
-	/* cache the first coherent kmap pte */
-	vaddr = __fix_to_virt(FIX_CMAP_BEGIN);
-	kmap_coherent_pte = kmap_get_fixmap_pte(vaddr);
-}
-#else
-static inline void kmap_coherent_init(void) {}
-#endif
-
 void *kmap_coherent(struct page *page, unsigned long addr)
 {
 	enum fixed_addresses idx;
@@ -126,12 +91,7 @@ void *kmap_coherent(struct page *page, unsigned long addr)
 
 	pagefault_disable();
 	idx = (addr >> PAGE_SHIFT) & (FIX_N_COLOURS - 1);
-#ifdef CONFIG_MIPS_MT_SMTC
-	idx += FIX_N_COLOURS * smp_processor_id() +
-		(in_interrupt() ? (FIX_N_COLOURS * NR_CPUS) : 0);
-#else
 	idx += in_interrupt() ? FIX_N_COLOURS : 0;
-#endif
 	vaddr = __fix_to_virt(FIX_CMAP_END - idx);
 	pte = mk_pte(page, PAGE_KERNEL);
 #if defined(CONFIG_64BIT_PHYS_ADDR) && defined(CONFIG_CPU_MIPS32)
@@ -140,44 +100,29 @@ void *kmap_coherent(struct page *page, unsigned long addr)
 	entrylo = pte_to_entrylo(pte_val(pte));
 #endif
 
-	ENTER_CRITICAL(flags);
+	local_irq_save(flags);
 	old_ctx = read_c0_entryhi();
 	write_c0_entryhi(vaddr & (PAGE_MASK << 1));
 	write_c0_entrylo0(entrylo);
 	write_c0_entrylo1(entrylo);
-#ifdef CONFIG_MIPS_MT_SMTC
-	set_pte(kmap_coherent_pte - (FIX_CMAP_END - idx), pte);
-	/* preload TLB instead of local_flush_tlb_one() */
-	mtc0_tlbw_hazard();
-	tlb_probe();
-	tlb_probe_hazard();
-	tlbidx = read_c0_index();
-	mtc0_tlbw_hazard();
-	if (tlbidx < 0)
-		tlb_write_random();
-	else
-		tlb_write_indexed();
-#else
 	tlbidx = read_c0_wired();
 	write_c0_wired(tlbidx + 1);
 	write_c0_index(tlbidx);
 	mtc0_tlbw_hazard();
 	tlb_write_indexed();
-#endif
 	tlbw_use_hazard();
 	write_c0_entryhi(old_ctx);
-	EXIT_CRITICAL(flags);
+	local_irq_restore(flags);
 
 	return (void*) vaddr;
 }
 
 void kunmap_coherent(void)
 {
-#ifndef CONFIG_MIPS_MT_SMTC
 	unsigned int wired;
 	unsigned long flags, old_ctx;
 
-	ENTER_CRITICAL(flags);
+	local_irq_save(flags);
 	old_ctx = read_c0_entryhi();
 	wired = read_c0_wired() - 1;
 	write_c0_wired(wired);
@@ -189,8 +134,7 @@ void kunmap_coherent(void)
 	tlb_write_indexed();
 	tlbw_use_hazard();
 	write_c0_entryhi(old_ctx);
-	EXIT_CRITICAL(flags);
-#endif
+	local_irq_restore(flags);
 	pagefault_enable();
 }
 
@@ -256,7 +200,7 @@ EXPORT_SYMBOL_GPL(copy_from_user_page);
 void __init fixrange_init(unsigned long start, unsigned long end,
 	pgd_t *pgd_base)
 {
-#if defined(CONFIG_HIGHMEM) || defined(CONFIG_MIPS_MT_SMTC)
+#ifdef CONFIG_HIGHMEM
 	pgd_t *pgd;
 	pud_t *pud;
 	pmd_t *pmd;
@@ -327,8 +271,6 @@ void __init paging_init(void)
 #ifdef CONFIG_HIGHMEM
 	kmap_init();
 #endif
-	kmap_coherent_init();
-
 #ifdef CONFIG_ZONE_DMA
 	max_zone_pfns[ZONE_DMA] = MAX_DMA_PFN;
 #endif