text: /*
   * linux/arch/unicore32/mm/ioremap.c
   *
   * Code specific to PKUnity SoC and UniCore ISA
   *
   * Copyright (C) 2001-2010 GUAN Xue-tao
   *
   * This program is free software; you can redistribute it and/or modify
   * it under the terms of the GNU General Public License version 2 as
   * published by the Free Software Foundation.
   *
   *
   * Re-map IO memory to kernel address space so that we can access it.
   *
   * This allows a driver to remap an arbitrary region of bus memory into
   * virtual space.  One should *only* use readl, writel, memcpy_toio and
   * so on with such remapped areas.
   *
   * Because UniCore only has a 32-bit address space we can't address the
   * whole of the (physical) PCI space at once.  PCI huge-mode addressing
   * allows us to circumvent this restriction by splitting PCI space into
   * two 2GB chunks and mapping only one at a time into processor memory.
   * We use MMU protection domains to trap any attempt to access the bank
   * that is not currently mapped.  (This isn't fully implemented yet.)
   */
  #include <linux/module.h>
  #include <linux/errno.h>
  #include <linux/mm.h>
  #include <linux/vmalloc.h>
  #include <linux/io.h>
  
  #include <asm/cputype.h>
  #include <asm/cacheflush.h>
  #include <asm/mmu_context.h>
  #include <asm/pgalloc.h>
  #include <asm/tlbflush.h>
  #include <asm/sizes.h>
  
  #include <mach/map.h>
  #include "mm.h"
  
  /*
   * Used by ioremap() and iounmap() code to mark (super)section-mapped
   * I/O regions in vm_struct->flags field.
   */
  #define VM_UNICORE_SECTION_MAPPING	0x80000000
  
  int ioremap_page(unsigned long virt, unsigned long phys,
  		 const struct mem_type *mtype)
  {
  	return ioremap_page_range(virt, virt + PAGE_SIZE, phys,
  				  __pgprot(mtype->prot_pte));
  }
  EXPORT_SYMBOL(ioremap_page);
  
  /*
   * Section support is unsafe on SMP - If you iounmap and ioremap a region,
   * the other CPUs will not see this change until their next context switch.
   * Meanwhile, (eg) if an interrupt comes in on one of those other CPUs
   * which requires the new ioremap'd region to be referenced, the CPU will
   * reference the _old_ region.
   *
   * Note that get_vm_area_caller() allocates a guard 4K page, so we need to
   * mask the size back to 4MB aligned or we will overflow in the loop below.
   */
  static void unmap_area_sections(unsigned long virt, unsigned long size)
  {
  	unsigned long addr = virt, end = virt + (size & ~(SZ_4M - 1));
  	pgd_t *pgd;
  
  	flush_cache_vunmap(addr, end);
  	pgd = pgd_offset_k(addr);
  	do {
  		pmd_t pmd, *pmdp = pmd_offset((pud_t *)pgd, addr);
  
  		pmd = *pmdp;
  		if (!pmd_none(pmd)) {
  			/*
  			 * Clear the PMD from the page table, and
  			 * increment the kvm sequence so others
  			 * notice this change.
  			 *
  			 * Note: this is still racy on SMP machines.
  			 */
  			pmd_clear(pmdp);
  
  			/*
  			 * Free the page table, if there was one.
  			 */
  			if ((pmd_val(pmd) & PMD_TYPE_MASK) == PMD_TYPE_TABLE)
  				pte_free_kernel(&init_mm, pmd_page_vaddr(pmd));
  		}
  
  		addr += PGDIR_SIZE;
  		pgd++;
  	} while (addr < end);
  
  	flush_tlb_kernel_range(virt, end);
  }
  
  static int
  remap_area_sections(unsigned long virt, unsigned long pfn,
  		    size_t size, const struct mem_type *type)
  {
  	unsigned long addr = virt, end = virt + size;
  	pgd_t *pgd;
  
  	/*
  	 * Remove and free any PTE-based mapping, and
  	 * sync the current kernel mapping.
  	 */
  	unmap_area_sections(virt, size);
  
  	pgd = pgd_offset_k(addr);
  	do {
  		pmd_t *pmd = pmd_offset((pud_t *)pgd, addr);
  
  		set_pmd(pmd, __pmd(__pfn_to_phys(pfn) | type->prot_sect));
  		pfn += SZ_4M >> PAGE_SHIFT;
  		flush_pmd_entry(pmd);
  
  		addr += PGDIR_SIZE;
  		pgd++;
  	} while (addr < end);
  
  	return 0;
  }
  
  void __iomem *__uc32_ioremap_pfn_caller(unsigned long pfn,
  	unsigned long offset, size_t size, unsigned int mtype, void *caller)
  {
  	const struct mem_type *type;
  	int err;
  	unsigned long addr;
  	struct vm_struct *area;
  
  	/*
  	 * High mappings must be section aligned
  	 */
  	if (pfn >= 0x100000 && (__pfn_to_phys(pfn) & ~SECTION_MASK))
  		return NULL;
  
  	/*
  	 * Don't allow RAM to be mapped
  	 */
  	if (pfn_valid(pfn)) {
  		printk(KERN_WARNING "BUG: Your driver calls ioremap() on\n"
  			"system memory.  This leads to architecturally\n"
  			"unpredictable behaviour, and ioremap() will fail in\n"
  			"the next kernel release. Please fix your driver.\n");
  		WARN_ON(1);
  	}
  
  	type = get_mem_type(mtype);
  	if (!type)
  		return NULL;
  
  	/*
  	 * Page align the mapping size, taking account of any offset.
  	 */
  	size = PAGE_ALIGN(offset + size);
  
  	area = get_vm_area_caller(size, VM_IOREMAP, caller);
  	if (!area)
  		return NULL;
  	addr = (unsigned long)area->addr;
  
  	if (!((__pfn_to_phys(pfn) | size | addr) & ~PMD_MASK)) {
  		area->flags |= VM_UNICORE_SECTION_MAPPING;
  		err = remap_area_sections(addr, pfn, size, type);
  	} else
  		err = ioremap_page_range(addr, addr + size, __pfn_to_phys(pfn),
  					 __pgprot(type->prot_pte));
  
  	if (err) {
  		vunmap((void *)addr);
  		return NULL;
  	}
  
  	flush_cache_vmap(addr, addr + size);
  	return (void __iomem *) (offset + addr);
  }
  
  void __iomem *__uc32_ioremap_caller(unsigned long phys_addr, size_t size,
  	unsigned int mtype, void *caller)
  {
  	unsigned long last_addr;
  	unsigned long offset = phys_addr & ~PAGE_MASK;
  	unsigned long pfn = __phys_to_pfn(phys_addr);
  
  	/*
  	 * Don't allow wraparound or zero size
  	 */
  	last_addr = phys_addr + size - 1;
  	if (!size || last_addr < phys_addr)
  		return NULL;
  
  	return __uc32_ioremap_pfn_caller(pfn, offset, size, mtype, caller);
  }
  
  /*
   * Remap an arbitrary physical address space into the kernel virtual
   * address space. Needed when the kernel wants to access high addresses
   * directly.
   *
   * NOTE! We need to allow non-page-aligned mappings too: we will obviously
   * have to convert them into an offset in a page-aligned mapping, but the
   * caller shouldn't need to know that small detail.
   */
  void __iomem *
  __uc32_ioremap_pfn(unsigned long pfn, unsigned long offset, size_t size,
  		  unsigned int mtype)
  {
  	return __uc32_ioremap_pfn_caller(pfn, offset, size, mtype,
  			__builtin_return_address(0));
  }
  EXPORT_SYMBOL(__uc32_ioremap_pfn);
  
  void __iomem *
  __uc32_ioremap(unsigned long phys_addr, size_t size)
  {
  	return __uc32_ioremap_caller(phys_addr, size, MT_DEVICE,
  			__builtin_return_address(0));
  }
  EXPORT_SYMBOL(__uc32_ioremap);
  
  void __iomem *
  __uc32_ioremap_cached(unsigned long phys_addr, size_t size)
  {
  	return __uc32_ioremap_caller(phys_addr, size, MT_DEVICE_CACHED,
  			__builtin_return_address(0));
  }
  EXPORT_SYMBOL(__uc32_ioremap_cached);
  
  void __uc32_iounmap(volatile void __iomem *io_addr)
  {
  	void *addr = (void *)(PAGE_MASK & (unsigned long)io_addr);
  	struct vm_struct **p, *tmp;
  
  	/*
  	 * If this is a section based mapping we need to handle it
  	 * specially as the VM subsystem does not know how to handle
  	 * such a beast. We need the lock here b/c we need to clear
  	 * all the mappings before the area can be reclaimed
  	 * by someone else.
  	 */
  	write_lock(&vmlist_lock);
  	for (p = &vmlist ; (tmp = *p) ; p = &tmp->next) {
  		if ((tmp->flags & VM_IOREMAP) && (tmp->addr == addr)) {
  			if (tmp->flags & VM_UNICORE_SECTION_MAPPING) {
  				unmap_area_sections((unsigned long)tmp->addr,
  						    tmp->size);
  			}
  			break;
  		}
  	}
  	write_unlock(&vmlist_lock);
  
  	vunmap(addr);
  }
  EXPORT_SYMBOL(__uc32_iounmap);
  