metag: Memory management

Add memory management files for metag.

Meta's 32bit virtual address space is split into two halves:
 - local (0x08000000-0x7fffffff): traditionally local to a hardware
   thread and incoherent between hardware threads. Each hardware thread
   has it's own local MMU table. On Meta2 the local space can be
   globally coherent (GCOn) if the cache partitions coincide.
 - global (0x88000000-0xffff0000): coherent and traditionally global
   between hardware threads. On Meta2, each hardware thread has it's own
   global MMU table.

The low 128MiB of each half is non-MMUable and maps directly to the
physical address space:
 - 0x00010000-0x07ffffff: contains Meta core registers and maps SoC bus
 - 0x80000000-0x87ffffff: contains low latency global core memories

Linux usually further splits the local virtual address space like this:
 - 0x08000000-0x3fffffff: user mappings
 - 0x40000000-0x7fffffff: kernel mappings

Signed-off-by: James Hogan <james.hogan@imgtec.com>

1 files changed, 448 insertions, 0 deletions

diff --git a/arch/metag/mm/init.c b/arch/metag/mm/init.c
new file mode 100644
index 0000000..514376d
--- /dev/null
+++ b/arch/metag/mm/init.c
@@ -0,0 +1,448 @@
+/*
+ *  Copyright (C) 2005,2006,2007,2008,2009,2010 Imagination Technologies
+ *
+ */
+
+#include <linux/mm.h>
+#include <linux/swap.h>
+#include <linux/init.h>
+#include <linux/bootmem.h>
+#include <linux/pagemap.h>
+#include <linux/percpu.h>
+#include <linux/memblock.h>
+#include <linux/initrd.h>
+#include <linux/of_fdt.h>
+
+#include <asm/setup.h>
+#include <asm/page.h>
+#include <asm/pgalloc.h>
+#include <asm/mmu.h>
+#include <asm/mmu_context.h>
+#include <asm/sections.h>
+#include <asm/tlb.h>
+#include <asm/user_gateway.h>
+#include <asm/mmzone.h>
+#include <asm/fixmap.h>
+
+unsigned long pfn_base;
+
+pgd_t swapper_pg_dir[PTRS_PER_PGD] __page_aligned_data;
+
+unsigned long empty_zero_page;
+
+extern char __user_gateway_start;
+extern char __user_gateway_end;
+
+void *gateway_page;
+
+/*
+ * Insert the gateway page into a set of page tables, creating the
+ * page tables if necessary.
+ */
+static void insert_gateway_page(pgd_t *pgd, unsigned long address)
+{
+	pud_t *pud;
+	pmd_t *pmd;
+	pte_t *pte;
+
+	BUG_ON(!pgd_present(*pgd));
+
+	pud = pud_offset(pgd, address);
+	BUG_ON(!pud_present(*pud));
+
+	pmd = pmd_offset(pud, address);
+	if (!pmd_present(*pmd)) {
+		pte = alloc_bootmem_pages(PAGE_SIZE);
+		set_pmd(pmd, __pmd(_PAGE_TABLE | __pa(pte)));
+	}
+
+	pte = pte_offset_kernel(pmd, address);
+	set_pte(pte, pfn_pte(__pa(gateway_page) >> PAGE_SHIFT, PAGE_READONLY));
+}
+
+/* Alloc and map a page in a known location accessible to userspace. */
+static void __init user_gateway_init(void)
+{
+	unsigned long address = USER_GATEWAY_PAGE;
+	int offset = pgd_index(address);
+	pgd_t *pgd;
+
+	gateway_page = alloc_bootmem_pages(PAGE_SIZE);
+
+	pgd = swapper_pg_dir + offset;
+	insert_gateway_page(pgd, address);
+
+#ifdef CONFIG_METAG_META12
+	/*
+	 * Insert the gateway page into our current page tables even
+	 * though we've already inserted it into our reference page
+	 * table (swapper_pg_dir). This is because with a META1 mmu we
+	 * copy just the user address range and not the gateway page
+	 * entry on context switch, see switch_mmu().
+	 */
+	pgd = (pgd_t *)mmu_get_base() + offset;
+	insert_gateway_page(pgd, address);
+#endif /* CONFIG_METAG_META12 */
+
+	BUG_ON((&__user_gateway_end - &__user_gateway_start) > PAGE_SIZE);
+
+	gateway_page += (address & ~PAGE_MASK);
+
+	memcpy(gateway_page, &__user_gateway_start,
+	       &__user_gateway_end - &__user_gateway_start);
+
+	/*
+	 * We don't need to flush the TLB here, there should be no mapping
+	 * present at boot for this address and only valid mappings are in
+	 * the TLB (apart from on Meta 1.x, but those cached invalid
+	 * mappings should be impossible to hit here).
+	 *
+	 * We don't flush the code cache here even though we have written
+	 * code through the data cache and they may not be coherent. At
+	 * this point we assume there is no stale data in the code cache
+	 * for this address so there is no need to flush.
+	 */
+}
+
+static void __init allocate_pgdat(unsigned int nid)
+{
+	unsigned long start_pfn, end_pfn;
+#ifdef CONFIG_NEED_MULTIPLE_NODES
+	unsigned long phys;
+#endif
+
+	get_pfn_range_for_nid(nid, &start_pfn, &end_pfn);
+
+#ifdef CONFIG_NEED_MULTIPLE_NODES
+	phys = __memblock_alloc_base(sizeof(struct pglist_data),
+				SMP_CACHE_BYTES, end_pfn << PAGE_SHIFT);
+	/* Retry with all of system memory */
+	if (!phys)
+		phys = __memblock_alloc_base(sizeof(struct pglist_data),
+					     SMP_CACHE_BYTES,
+					     memblock_end_of_DRAM());
+	if (!phys)
+		panic("Can't allocate pgdat for node %d\n", nid);
+
+	NODE_DATA(nid) = __va(phys);
+	memset(NODE_DATA(nid), 0, sizeof(struct pglist_data));
+
+	NODE_DATA(nid)->bdata = &bootmem_node_data[nid];
+#endif
+
+	NODE_DATA(nid)->node_start_pfn = start_pfn;
+	NODE_DATA(nid)->node_spanned_pages = end_pfn - start_pfn;
+}
+
+static void __init bootmem_init_one_node(unsigned int nid)
+{
+	unsigned long total_pages, paddr;
+	unsigned long end_pfn;
+	struct pglist_data *p;
+
+	p = NODE_DATA(nid);
+
+	/* Nothing to do.. */
+	if (!p->node_spanned_pages)
+		return;
+
+	end_pfn = p->node_start_pfn + p->node_spanned_pages;
+#ifdef CONFIG_HIGHMEM
+	if (end_pfn > max_low_pfn)
+		end_pfn = max_low_pfn;
+#endif
+
+	total_pages = bootmem_bootmap_pages(end_pfn - p->node_start_pfn);
+
+	paddr = memblock_alloc(total_pages << PAGE_SHIFT, PAGE_SIZE);
+	if (!paddr)
+		panic("Can't allocate bootmap for nid[%d]\n", nid);
+
+	init_bootmem_node(p, paddr >> PAGE_SHIFT, p->node_start_pfn, end_pfn);
+
+	free_bootmem_with_active_regions(nid, end_pfn);
+
+	/*
+	 * XXX Handle initial reservations for the system memory node
+	 * only for the moment, we'll refactor this later for handling
+	 * reservations in other nodes.
+	 */
+	if (nid == 0) {
+		struct memblock_region *reg;
+
+		/* Reserve the sections we're already using. */
+		for_each_memblock(reserved, reg) {
+			unsigned long size = reg->size;
+
+#ifdef CONFIG_HIGHMEM
+			/* ...but not highmem */
+			if (PFN_DOWN(reg->base) >= highstart_pfn)
+				continue;
+
+			if (PFN_UP(reg->base + size) > highstart_pfn)
+				size = (highstart_pfn - PFN_DOWN(reg->base))
+				       << PAGE_SHIFT;
+#endif
+
+			reserve_bootmem(reg->base, size, BOOTMEM_DEFAULT);
+		}
+	}
+
+	sparse_memory_present_with_active_regions(nid);
+}
+
+static void __init do_init_bootmem(void)
+{
+	struct memblock_region *reg;
+	int i;
+
+	/* Add active regions with valid PFNs. */
+	for_each_memblock(memory, reg) {
+		unsigned long start_pfn, end_pfn;
+		start_pfn = memblock_region_memory_base_pfn(reg);
+		end_pfn = memblock_region_memory_end_pfn(reg);
+		memblock_set_node(PFN_PHYS(start_pfn),
+				  PFN_PHYS(end_pfn - start_pfn), 0);
+	}
+
+	/* All of system RAM sits in node 0 for the non-NUMA case */
+	allocate_pgdat(0);
+	node_set_online(0);
+
+	soc_mem_setup();
+
+	for_each_online_node(i)
+		bootmem_init_one_node(i);
+
+	sparse_init();
+}
+
+extern char _heap_start[];
+
+static void __init init_and_reserve_mem(void)
+{
+	unsigned long start_pfn, heap_start;
+	u64 base = min_low_pfn << PAGE_SHIFT;
+	u64 size = (max_low_pfn << PAGE_SHIFT) - base;
+
+	heap_start = (unsigned long) &_heap_start;
+
+	memblock_add(base, size);
+
+	/*
+	 * Partially used pages are not usable - thus
+	 * we are rounding upwards:
+	 */
+	start_pfn = PFN_UP(__pa(heap_start));
+
+	/*
+	 * Reserve the kernel text.
+	 */
+	memblock_reserve(base, (PFN_PHYS(start_pfn) + PAGE_SIZE - 1) - base);
+
+#ifdef CONFIG_HIGHMEM
+	/*
+	 * Add & reserve highmem, so page structures are initialised.
+	 */
+	base = highstart_pfn << PAGE_SHIFT;
+	size = (highend_pfn << PAGE_SHIFT) - base;
+	if (size) {
+		memblock_add(base, size);
+		memblock_reserve(base, size);
+	}
+#endif
+}
+
+#ifdef CONFIG_HIGHMEM
+/*
+ * Ensure we have allocated page tables in swapper_pg_dir for the
+ * fixed mappings range from 'start' to 'end'.
+ */
+static void __init allocate_pgtables(unsigned long start, unsigned long end)
+{
+	pgd_t *pgd;
+	pmd_t *pmd;
+	pte_t *pte;
+	int i, j;
+	unsigned long vaddr;
+
+	vaddr = start;
+	i = pgd_index(vaddr);
+	j = pmd_index(vaddr);
+	pgd = swapper_pg_dir + i;
+
+	for ( ; (i < PTRS_PER_PGD) && (vaddr != end); pgd++, i++) {
+		pmd = (pmd_t *)pgd;
+		for (; (j < PTRS_PER_PMD) && (vaddr != end); pmd++, j++) {
+			vaddr += PMD_SIZE;
+
+			if (!pmd_none(*pmd))
+				continue;
+
+			pte = (pte_t *)alloc_bootmem_low_pages(PAGE_SIZE);
+			pmd_populate_kernel(&init_mm, pmd, pte);
+		}
+		j = 0;
+	}
+}
+
+static void __init fixedrange_init(void)
+{
+	unsigned long vaddr, end;
+	pgd_t *pgd;
+	pud_t *pud;
+	pmd_t *pmd;
+	pte_t *pte;
+
+	/*
+	 * Fixed mappings:
+	 */
+	vaddr = __fix_to_virt(__end_of_fixed_addresses - 1) & PMD_MASK;
+	end = (FIXADDR_TOP + PMD_SIZE - 1) & PMD_MASK;
+	allocate_pgtables(vaddr, end);
+
+	/*
+	 * Permanent kmaps:
+	 */
+	vaddr = PKMAP_BASE;
+	allocate_pgtables(vaddr, vaddr + PAGE_SIZE*LAST_PKMAP);
+
+	pgd = swapper_pg_dir + pgd_index(vaddr);
+	pud = pud_offset(pgd, vaddr);
+	pmd = pmd_offset(pud, vaddr);
+	pte = pte_offset_kernel(pmd, vaddr);
+	pkmap_page_table = pte;
+}
+#endif /* CONFIG_HIGHMEM */
+
+/*
+ * paging_init() continues the virtual memory environment setup which
+ * was begun by the code in arch/metag/kernel/setup.c.
+ */
+void __init paging_init(unsigned long mem_end)
+{
+	unsigned long max_zone_pfns[MAX_NR_ZONES];
+	int nid;
+
+	init_and_reserve_mem();
+
+	memblock_allow_resize();
+
+	memblock_dump_all();
+
+	nodes_clear(node_online_map);
+
+	init_new_context(&init_task, &init_mm);
+
+	memset(swapper_pg_dir, 0, sizeof(swapper_pg_dir));
+
+	do_init_bootmem();
+	mmu_init(mem_end);
+
+#ifdef CONFIG_HIGHMEM
+	fixedrange_init();
+	kmap_init();
+#endif
+
+	/* Initialize the zero page to a bootmem page, already zeroed. */
+	empty_zero_page = (unsigned long)alloc_bootmem_pages(PAGE_SIZE);
+
+	user_gateway_init();
+
+	memset(max_zone_pfns, 0, sizeof(max_zone_pfns));
+
+	for_each_online_node(nid) {
+		pg_data_t *pgdat = NODE_DATA(nid);
+		unsigned long low, start_pfn;
+
+		start_pfn = pgdat->bdata->node_min_pfn;
+		low = pgdat->bdata->node_low_pfn;
+
+		if (max_zone_pfns[ZONE_NORMAL] < low)
+			max_zone_pfns[ZONE_NORMAL] = low;
+
+#ifdef CONFIG_HIGHMEM
+		max_zone_pfns[ZONE_HIGHMEM] = highend_pfn;
+#endif
+		pr_info("Node %u: start_pfn = 0x%lx, low = 0x%lx\n",
+			nid, start_pfn, low);
+	}
+
+	free_area_init_nodes(max_zone_pfns);
+}
+
+void __init mem_init(void)
+{
+	int nid;
+
+#ifdef CONFIG_HIGHMEM
+	unsigned long tmp;
+	for (tmp = highstart_pfn; tmp < highend_pfn; tmp++) {
+		struct page *page = pfn_to_page(tmp);
+		ClearPageReserved(page);
+		init_page_count(page);
+		__free_page(page);
+		totalhigh_pages++;
+	}
+	totalram_pages += totalhigh_pages;
+	num_physpages += totalhigh_pages;
+#endif /* CONFIG_HIGHMEM */
+
+	for_each_online_node(nid) {
+		pg_data_t *pgdat = NODE_DATA(nid);
+		unsigned long node_pages = 0;
+
+		num_physpages += pgdat->node_present_pages;
+
+		if (pgdat->node_spanned_pages)
+			node_pages = free_all_bootmem_node(pgdat);
+
+		totalram_pages += node_pages;
+	}
+
+	pr_info("Memory: %luk/%luk available\n",
+		(unsigned long)nr_free_pages() << (PAGE_SHIFT - 10),
+		num_physpages << (PAGE_SHIFT - 10));
+
+	show_mem(0);
+
+	return;
+}
+
+static void free_init_pages(char *what, unsigned long begin, unsigned long end)
+{
+	unsigned long addr;
+
+	for (addr = begin; addr < end; addr += PAGE_SIZE) {
+		ClearPageReserved(virt_to_page(addr));
+		init_page_count(virt_to_page(addr));
+		memset((void *)addr, POISON_FREE_INITMEM, PAGE_SIZE);
+		free_page(addr);
+		totalram_pages++;
+	}
+	pr_info("Freeing %s: %luk freed\n", what, (end - begin) >> 10);
+}
+
+void free_initmem(void)
+{
+	free_init_pages("unused kernel memory",
+			(unsigned long)(&__init_begin),
+			(unsigned long)(&__init_end));
+}
+
+#ifdef CONFIG_BLK_DEV_INITRD
+void free_initrd_mem(unsigned long start, unsigned long end)
+{
+	end = end & PAGE_MASK;
+	free_init_pages("initrd memory", start, end);
+}
+#endif
+
+#ifdef CONFIG_OF_FLATTREE
+void __init early_init_dt_setup_initrd_arch(unsigned long start,
+					    unsigned long end)
+{
+	pr_err("%s(%lx, %lx)\n",
+	       __func__, start, end);
+}
+#endif /* CONFIG_OF_FLATTREE */