text: // SPDX-License-Identifier: GPL-2.0
  /*
   * linux/arch/m68k/mm/motorola.c
   *
   * Routines specific to the Motorola MMU, originally from:
   * linux/arch/m68k/init.c
   * which are Copyright (C) 1995 Hamish Macdonald
   *
   * Moved 8/20/1999 Sam Creasey
   */
  
  #include <linux/module.h>
  #include <linux/signal.h>
  #include <linux/sched.h>
  #include <linux/mm.h>
  #include <linux/swap.h>
  #include <linux/kernel.h>
  #include <linux/string.h>
  #include <linux/types.h>
  #include <linux/init.h>
  #include <linux/memblock.h>
  #include <linux/gfp.h>
  
  #include <asm/setup.h>
  #include <linux/uaccess.h>
  #include <asm/page.h>
  #include <asm/pgalloc.h>
  #include <asm/machdep.h>
  #include <asm/io.h>
  #include <asm/dma.h>
  #ifdef CONFIG_ATARI
  #include <asm/atari_stram.h>
  #endif
  #include <asm/sections.h>
  
  #undef DEBUG
  
  #ifndef mm_cachebits
  /*
   * Bits to add to page descriptors for "normal" caching mode.
   * For 68020/030 this is 0.
   * For 68040, this is _PAGE_CACHE040 (cachable, copyback)
   */
  unsigned long mm_cachebits;
  EXPORT_SYMBOL(mm_cachebits);
  #endif
  
  /* size of memory already mapped in head.S */
  extern __initdata unsigned long m68k_init_mapped_size;
  
  extern unsigned long availmem;
  
  static pte_t * __init kernel_page_table(void)
  {
  	pte_t *ptablep;
  
  	ptablep = (pte_t *)memblock_alloc_low(PAGE_SIZE, PAGE_SIZE);
  	if (!ptablep)
  		panic("%s: Failed to allocate %lu bytes align=%lx\n",
  		      __func__, PAGE_SIZE, PAGE_SIZE);
  
  	clear_page(ptablep);
  	__flush_page_to_ram(ptablep);
  	flush_tlb_kernel_page(ptablep);
  	nocache_page(ptablep);
  
  	return ptablep;
  }
  
  static pmd_t *last_pgtable __initdata = NULL;
  pmd_t *zero_pgtable __initdata = NULL;
  
  static pmd_t * __init kernel_ptr_table(void)
  {
  	if (!last_pgtable) {
  		unsigned long pmd, last;
  		int i;
  
  		/* Find the last ptr table that was used in head.S and
  		 * reuse the remaining space in that page for further
  		 * ptr tables.
  		 */
  		last = (unsigned long)kernel_pg_dir;
  		for (i = 0; i < PTRS_PER_PGD; i++) {
  			if (!pgd_present(kernel_pg_dir[i]))
  				continue;
  			pmd = __pgd_page(kernel_pg_dir[i]);
  			if (pmd > last)
  				last = pmd;
  		}
  
  		last_pgtable = (pmd_t *)last;
  #ifdef DEBUG
  		printk("kernel_ptr_init: %p\n", last_pgtable);
  #endif
  	}
  
  	last_pgtable += PTRS_PER_PMD;
  	if (((unsigned long)last_pgtable & ~PAGE_MASK) == 0) {
  		last_pgtable = (pmd_t *)memblock_alloc_low(PAGE_SIZE,
  							   PAGE_SIZE);
  		if (!last_pgtable)
  			panic("%s: Failed to allocate %lu bytes align=%lx\n",
  			      __func__, PAGE_SIZE, PAGE_SIZE);
  
  		clear_page(last_pgtable);
  		__flush_page_to_ram(last_pgtable);
  		flush_tlb_kernel_page(last_pgtable);
  		nocache_page(last_pgtable);
  	}
  
  	return last_pgtable;
  }
  
  static void __init map_node(int node)
  {
  #define PTRTREESIZE (256*1024)
  #define ROOTTREESIZE (32*1024*1024)
  	unsigned long physaddr, virtaddr, size;
  	pgd_t *pgd_dir;
  	pmd_t *pmd_dir;
  	pte_t *pte_dir;
  
  	size = m68k_memory[node].size;
  	physaddr = m68k_memory[node].addr;
  	virtaddr = (unsigned long)phys_to_virt(physaddr);
  	physaddr |= m68k_supervisor_cachemode |
  		    _PAGE_PRESENT | _PAGE_ACCESSED | _PAGE_DIRTY;
  	if (CPU_IS_040_OR_060)
  		physaddr |= _PAGE_GLOBAL040;
  
  	while (size > 0) {
  #ifdef DEBUG
  		if (!(virtaddr & (PTRTREESIZE-1)))
  			printk ("\npa=%#lx va=%#lx ", physaddr & PAGE_MASK,
  				virtaddr);
  #endif
  		pgd_dir = pgd_offset_k(virtaddr);
  		if (virtaddr && CPU_IS_020_OR_030) {
  			if (!(virtaddr & (ROOTTREESIZE-1)) &&
  			    size >= ROOTTREESIZE) {
  #ifdef DEBUG
  				printk ("[very early term]");
  #endif
  				pgd_val(*pgd_dir) = physaddr;
  				size -= ROOTTREESIZE;
  				virtaddr += ROOTTREESIZE;
  				physaddr += ROOTTREESIZE;
  				continue;
  			}
  		}
  		if (!pgd_present(*pgd_dir)) {
  			pmd_dir = kernel_ptr_table();
  #ifdef DEBUG
  			printk ("[new pointer %p]", pmd_dir);
  #endif
  			pgd_set(pgd_dir, pmd_dir);
  		} else
  			pmd_dir = pmd_offset(pgd_dir, virtaddr);
  
  		if (CPU_IS_020_OR_030) {
  			if (virtaddr) {
  #ifdef DEBUG
  				printk ("[early term]");
  #endif
  				pmd_dir->pmd[(virtaddr/PTRTREESIZE) & 15] = physaddr;
  				physaddr += PTRTREESIZE;
  			} else {
  				int i;
  #ifdef DEBUG
  				printk ("[zero map]");
  #endif
  				zero_pgtable = kernel_ptr_table();
  				pte_dir = (pte_t *)zero_pgtable;
  				pmd_dir->pmd[0] = virt_to_phys(pte_dir) |
  					_PAGE_TABLE | _PAGE_ACCESSED;
  				pte_val(*pte_dir++) = 0;
  				physaddr += PAGE_SIZE;
  				for (i = 1; i < 64; physaddr += PAGE_SIZE, i++)
  					pte_val(*pte_dir++) = physaddr;
  			}
  			size -= PTRTREESIZE;
  			virtaddr += PTRTREESIZE;
  		} else {
  			if (!pmd_present(*pmd_dir)) {
  #ifdef DEBUG
  				printk ("[new table]");
  #endif
  				pte_dir = kernel_page_table();
  				pmd_set(pmd_dir, pte_dir);
  			}
  			pte_dir = pte_offset_kernel(pmd_dir, virtaddr);
  
  			if (virtaddr) {
  				if (!pte_present(*pte_dir))
  					pte_val(*pte_dir) = physaddr;
  			} else
  				pte_val(*pte_dir) = 0;
  			size -= PAGE_SIZE;
  			virtaddr += PAGE_SIZE;
  			physaddr += PAGE_SIZE;
  		}
  
  	}
  #ifdef DEBUG
  	printk("\n");
  #endif
  }
  
  /*
   * paging_init() continues the virtual memory environment setup which
   * was begun by the code in arch/head.S.
   */
  void __init paging_init(void)
  {
  	unsigned long zones_size[MAX_NR_ZONES] = { 0, };
  	unsigned long min_addr, max_addr;
  	unsigned long addr;
  	int i;
  
  #ifdef DEBUG
  	printk ("start of paging_init (%p, %lx)\n", kernel_pg_dir, availmem);
  #endif
  
  	/* Fix the cache mode in the page descriptors for the 680[46]0.  */
  	if (CPU_IS_040_OR_060) {
  		int i;
  #ifndef mm_cachebits
  		mm_cachebits = _PAGE_CACHE040;
  #endif
  		for (i = 0; i < 16; i++)
  			pgprot_val(protection_map[i]) |= _PAGE_CACHE040;
  	}
  
  	min_addr = m68k_memory[0].addr;
  	max_addr = min_addr + m68k_memory[0].size;
  	memblock_add(m68k_memory[0].addr, m68k_memory[0].size);
  	for (i = 1; i < m68k_num_memory;) {
  		if (m68k_memory[i].addr < min_addr) {
  			printk("Ignoring memory chunk at 0x%lx:0x%lx before the first chunk\n",
  				m68k_memory[i].addr, m68k_memory[i].size);
  			printk("Fix your bootloader or use a memfile to make use of this area!\n");
  			m68k_num_memory--;
  			memmove(m68k_memory + i, m68k_memory + i + 1,
  				(m68k_num_memory - i) * sizeof(struct m68k_mem_info));
  			continue;
  		}
  		memblock_add(m68k_memory[i].addr, m68k_memory[i].size);
  		addr = m68k_memory[i].addr + m68k_memory[i].size;
  		if (addr > max_addr)
  			max_addr = addr;
  		i++;
  	}
  	m68k_memoffset = min_addr - PAGE_OFFSET;
  	m68k_virt_to_node_shift = fls(max_addr - min_addr - 1) - 6;
  
  	module_fixup(NULL, __start_fixup, __stop_fixup);
  	flush_icache();
  
  	high_memory = phys_to_virt(max_addr);
  
  	min_low_pfn = availmem >> PAGE_SHIFT;
  	max_pfn = max_low_pfn = max_addr >> PAGE_SHIFT;
  
  	/* Reserve kernel text/data/bss and the memory allocated in head.S */
  	memblock_reserve(m68k_memory[0].addr, availmem - m68k_memory[0].addr);
  
  	/*
  	 * Map the physical memory available into the kernel virtual
  	 * address space. Make sure memblock will not try to allocate
  	 * pages beyond the memory we already mapped in head.S
  	 */
  	memblock_set_bottom_up(true);
  
  	for (i = 0; i < m68k_num_memory; i++) {
  		m68k_setup_node(i);
  		map_node(i);
  	}
  
  	flush_tlb_all();
  
  	/*
  	 * initialize the bad page table and bad page to point
  	 * to a couple of allocated pages
  	 */
  	empty_zero_page = memblock_alloc(PAGE_SIZE, PAGE_SIZE);
  	if (!empty_zero_page)
  		panic("%s: Failed to allocate %lu bytes align=0x%lx\n",
  		      __func__, PAGE_SIZE, PAGE_SIZE);
  
  	/*
  	 * Set up SFC/DFC registers
  	 */
  	set_fs(KERNEL_DS);
  
  #ifdef DEBUG
  	printk ("before free_area_init\n");
  #endif
  	for (i = 0; i < m68k_num_memory; i++) {
  		zones_size[ZONE_DMA] = m68k_memory[i].size >> PAGE_SHIFT;
  		free_area_init_node(i, zones_size,
  				    m68k_memory[i].addr >> PAGE_SHIFT, NULL);
  		if (node_present_pages(i))
  			node_set_state(i, N_NORMAL_MEMORY);
  	}
  }
  
  