csky: MMU and page table management

This patch adds files related to memory management and here is our
memory-layout:

   Fixmap       : 0xffc02000 – 0xfffff000       (4 MB - 12KB)
   Pkmap        : 0xff800000 – 0xffc00000       (4 MB)
   Vmalloc      : 0xf0200000 – 0xff000000       (238 MB)
   Lowmem       : 0x80000000 – 0xc0000000       (1GB)

abiv1 CPU (CK610) is VIPT cache and it doesn't support highmem.
abiv2 CPUs are all PIPT cache and they could support highmem.

Lowmem is directly mapped by msa0 & msa1 reg, and we needn't setup
memory page table for it.

Link:https://lore.kernel.org/lkml/20180518215548.GH17671@n2100.armlinux.org.uk/
Signed-off-by: Guo Ren <ren_guo@c-sky.com>
Cc: Christoph Hellwig <hch@infradead.org>
Reviewed-by: Arnd Bergmann <arnd@arndb.de>

1 files changed, 115 insertions, 0 deletions

diff --git a/arch/csky/include/asm/pgalloc.h b/arch/csky/include/asm/pgalloc.h
new file mode 100644
index 000000000000..bf4f4a0e140e
--- /dev/null
+++ b/arch/csky/include/asm/pgalloc.h
@@ -0,0 +1,115 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+// Copyright (C) 2018 Hangzhou C-SKY Microsystems co.,ltd.
+
+#ifndef __ASM_CSKY_PGALLOC_H
+#define __ASM_CSKY_PGALLOC_H
+
+#include <linux/highmem.h>
+#include <linux/mm.h>
+#include <linux/sched.h>
+
+static inline void pmd_populate_kernel(struct mm_struct *mm, pmd_t *pmd,
+					pte_t *pte)
+{
+	set_pmd(pmd, __pmd(__pa(pte)));
+}
+
+static inline void pmd_populate(struct mm_struct *mm, pmd_t *pmd,
+					pgtable_t pte)
+{
+	set_pmd(pmd, __pmd(__pa(page_address(pte))));
+}
+
+#define pmd_pgtable(pmd) pmd_page(pmd)
+
+extern void pgd_init(unsigned long *p);
+
+static inline pte_t *pte_alloc_one_kernel(struct mm_struct *mm,
+					unsigned long address)
+{
+	pte_t *pte;
+	unsigned long *kaddr, i;
+
+	pte = (pte_t *) __get_free_pages(GFP_KERNEL | __GFP_RETRY_MAYFAIL,
+					 PTE_ORDER);
+	kaddr = (unsigned long *)pte;
+	if (address & 0x80000000)
+		for (i = 0; i < (PAGE_SIZE/4); i++)
+			*(kaddr + i) = 0x1;
+	else
+		clear_page(kaddr);
+
+	return pte;
+}
+
+static inline struct page *pte_alloc_one(struct mm_struct *mm,
+						unsigned long address)
+{
+	struct page *pte;
+	unsigned long *kaddr, i;
+
+	pte = alloc_pages(GFP_KERNEL | __GFP_RETRY_MAYFAIL, PTE_ORDER);
+	if (pte) {
+		kaddr = kmap_atomic(pte);
+		if (address & 0x80000000) {
+			for (i = 0; i < (PAGE_SIZE/4); i++)
+				*(kaddr + i) = 0x1;
+		} else
+			clear_page(kaddr);
+		kunmap_atomic(kaddr);
+		pgtable_page_ctor(pte);
+	}
+	return pte;
+}
+
+static inline void pte_free_kernel(struct mm_struct *mm, pte_t *pte)
+{
+	free_pages((unsigned long)pte, PTE_ORDER);
+}
+
+static inline void pte_free(struct mm_struct *mm, pgtable_t pte)
+{
+	pgtable_page_dtor(pte);
+	__free_pages(pte, PTE_ORDER);
+}
+
+static inline void pgd_free(struct mm_struct *mm, pgd_t *pgd)
+{
+	free_pages((unsigned long)pgd, PGD_ORDER);
+}
+
+static inline pgd_t *pgd_alloc(struct mm_struct *mm)
+{
+	pgd_t *ret;
+	pgd_t *init;
+
+	ret = (pgd_t *) __get_free_pages(GFP_KERNEL, PGD_ORDER);
+	if (ret) {
+		init = pgd_offset(&init_mm, 0UL);
+		pgd_init((unsigned long *)ret);
+		memcpy(ret + USER_PTRS_PER_PGD, init + USER_PTRS_PER_PGD,
+			(PTRS_PER_PGD - USER_PTRS_PER_PGD) * sizeof(pgd_t));
+		/* prevent out of order excute */
+		smp_mb();
+#ifdef CONFIG_CPU_NEED_TLBSYNC
+		dcache_wb_range((unsigned int)ret,
+				(unsigned int)(ret + PTRS_PER_PGD));
+#endif
+	}
+
+	return ret;
+}
+
+#define __pte_free_tlb(tlb, pte, address)		\
+do {							\
+	pgtable_page_dtor(pte);				\
+	tlb_remove_page(tlb, pte);			\
+} while (0)
+
+#define check_pgt_cache()	do {} while (0)
+
+extern void pagetable_init(void);
+extern void pre_mmu_init(void);
+extern void pre_trap_init(void);
+
+#endif /* __ASM_CSKY_PGALLOC_H */