csky: Improve tlb operation with help of asid

There are two generations of tlb operation instruction for C-SKY.
First generation is use mcr register and it need software do more
things, second generation is use specific instructions, eg:
 tlbi.va, tlbi.vas, tlbi.alls

We implemented the following functions:

 - flush_tlb_range (a range of entries)
 - flush_tlb_page (one entry)

 Above functions use asid from vma->mm to invalid tlb entries and
 we could use tlbi.vas instruction for newest generation csky cpu.

 - flush_tlb_kernel_range
 - flush_tlb_one

 Above functions don't care asid and it invalid the tlb entries only
 with vpn and we could use tlbi.vaas instruction for newest generat-
 ion csky cpu.
Signed-off-by: Guo Ren <ren_guo@c-sky.com>
Cc: Arnd Bergmann <arnd@arndb.de>

arch/csky/mm/tlb.c

@@ -10,6 +10,13 @@
 #include <asm/pgtable.h>
 #include <asm/setup.h>
 
+/*
+ * One C-SKY MMU TLB entry contain two PFN/page entry, ie:
+ * 1VPN -> 2PFN
+ */
+#define TLB_ENTRY_SIZE		(PAGE_SIZE * 2)
+#define TLB_ENTRY_SIZE_MASK	(PAGE_MASK << 1)
+
 void flush_tlb_all(void)
 {
 	tlb_invalid_all();
@@ -17,27 +24,148 @@ void flush_tlb_all(void)
 
 void flush_tlb_mm(struct mm_struct *mm)
 {
+#ifdef CONFIG_CPU_HAS_TLBI
+	asm volatile("tlbi.asids %0"::"r"(cpu_asid(mm)));
+#else
 	tlb_invalid_all();
+#endif
 }
 
+/*
+ * MMU operation regs only could invalid tlb entry in jtlb and we
+ * need change asid field to invalid I-utlb & D-utlb.
+ */
+#ifndef CONFIG_CPU_HAS_TLBI
+#define restore_asid_inv_utlb(oldpid, newpid) \
+do { \
+	if (oldpid == newpid) \
+		write_mmu_entryhi(oldpid + 1); \
+	write_mmu_entryhi(oldpid); \
+} while (0)
+#endif
+
 void flush_tlb_range(struct vm_area_struct *vma, unsigned long start,
 			unsigned long end)
 {
-	tlb_invalid_all();
+	unsigned long newpid = cpu_asid(vma->vm_mm);
+
+	start &= TLB_ENTRY_SIZE_MASK;
+	end   += TLB_ENTRY_SIZE - 1;
+	end   &= TLB_ENTRY_SIZE_MASK;
+
+#ifdef CONFIG_CPU_HAS_TLBI
+	while (start < end) {
+		asm volatile("tlbi.vas %0"::"r"(start | newpid));
+		start += 2*PAGE_SIZE;
+	}
+	sync_is();
+#else
+	{
+	unsigned long flags, oldpid;
+
+	local_irq_save(flags);
+	oldpid = read_mmu_entryhi() & ASID_MASK;
+	while (start < end) {
+		int idx;
+
+		write_mmu_entryhi(start | newpid);
+		start += 2*PAGE_SIZE;
+		tlb_probe();
+		idx = read_mmu_index();
+		if (idx >= 0)
+			tlb_invalid_indexed();
+	}
+	restore_asid_inv_utlb(oldpid, newpid);
+	local_irq_restore(flags);
+	}
+#endif
 }
 
 void flush_tlb_kernel_range(unsigned long start, unsigned long end)
 {
-	tlb_invalid_all();
+	start &= TLB_ENTRY_SIZE_MASK;
+	end   += TLB_ENTRY_SIZE - 1;
+	end   &= TLB_ENTRY_SIZE_MASK;
+
+#ifdef CONFIG_CPU_HAS_TLBI
+	while (start < end) {
+		asm volatile("tlbi.vaas %0"::"r"(start));
+		start += 2*PAGE_SIZE;
+	}
+	sync_is();
+#else
+	{
+	unsigned long flags, oldpid;
+
+	local_irq_save(flags);
+	oldpid = read_mmu_entryhi() & ASID_MASK;
+	while (start < end) {
+		int idx;
+
+		write_mmu_entryhi(start | oldpid);
+		start += 2*PAGE_SIZE;
+		tlb_probe();
+		idx = read_mmu_index();
+		if (idx >= 0)
+			tlb_invalid_indexed();
+	}
+	restore_asid_inv_utlb(oldpid, oldpid);
+	local_irq_restore(flags);
+	}
+#endif
 }
 
 void flush_tlb_page(struct vm_area_struct *vma, unsigned long addr)
 {
-	tlb_invalid_all();
+	int newpid = cpu_asid(vma->vm_mm);
+
+	addr &= TLB_ENTRY_SIZE_MASK;
+
+#ifdef CONFIG_CPU_HAS_TLBI
+	asm volatile("tlbi.vas %0"::"r"(addr | newpid));
+	sync_is();
+#else
+	{
+	int oldpid, idx;
+	unsigned long flags;
+
+	local_irq_save(flags);
+	oldpid = read_mmu_entryhi() & ASID_MASK;
+	write_mmu_entryhi(addr | newpid);
+	tlb_probe();
+	idx = read_mmu_index();
+	if (idx >= 0)
+		tlb_invalid_indexed();
+
+	restore_asid_inv_utlb(oldpid, newpid);
+	local_irq_restore(flags);
+	}
+#endif
 }
 
 void flush_tlb_one(unsigned long addr)
 {
-	tlb_invalid_all();
+	addr &= TLB_ENTRY_SIZE_MASK;
+
+#ifdef CONFIG_CPU_HAS_TLBI
+	asm volatile("tlbi.vaas %0"::"r"(addr));
+	sync_is();
+#else
+	{
+	int oldpid, idx;
+	unsigned long flags;
+
+	local_irq_save(flags);
+	oldpid = read_mmu_entryhi() & ASID_MASK;
+	write_mmu_entryhi(addr | oldpid);
+	tlb_probe();
+	idx = read_mmu_index();
+	if (idx >= 0)
+		tlb_invalid_indexed();
+
+	restore_asid_inv_utlb(oldpid, oldpid);
+	local_irq_restore(flags);
+	}
+#endif
 }
 EXPORT_SYMBOL(flush_tlb_one);