linux/arch/xtensa/mm/mmu.c

/*
 * xtensa mmu stuff
 *
 * Extracted from init.c
 */
#include <linux/percpu.h>
#include <linux/init.h>
#include <linux/string.h>
#include <linux/slab.h>
#include <linux/cache.h>

#include <asm/tlb.h>
#include <asm/tlbflush.h>
#include <asm/mmu_context.h>
#include <asm/page.h>
#include <asm/initialize_mmu.h>
#include <asm/io.h>

void __init paging_init(void)
{
	memset(swapper_pg_dir, 0, PAGE_SIZE);
}

/*
 * Flush the mmu and reset associated register to default values.
 */
void init_mmu(void)
{
#if !(XCHAL_HAVE_PTP_MMU && XCHAL_HAVE_SPANNING_WAY)
	/*
	 * Writing zeros to the instruction and data TLBCFG special
	 * registers ensure that valid values exist in the register.
	 *
	 * For existing PGSZID<w> fields, zero selects the first element
	 * of the page-size array.  For nonexistent PGSZID<w> fields,
	 * zero is the best value to write.  Also, when changing PGSZID<w>
	 * fields, the corresponding TLB must be flushed.
	 */
	set_itlbcfg_register(0);
	set_dtlbcfg_register(0);
#endif
#if XCHAL_HAVE_PTP_MMU && XCHAL_HAVE_SPANNING_WAY && defined(CONFIG_OF)
	/*
	 * Update the IO area mapping in case xtensa_kio_paddr has changed
	 */
	write_dtlb_entry(__pte(xtensa_kio_paddr + CA_WRITEBACK),
			XCHAL_KIO_CACHED_VADDR + 6);
	write_itlb_entry(__pte(xtensa_kio_paddr + CA_WRITEBACK),
			XCHAL_KIO_CACHED_VADDR + 6);
	write_dtlb_entry(__pte(xtensa_kio_paddr + CA_BYPASS),
			XCHAL_KIO_BYPASS_VADDR + 6);
	write_itlb_entry(__pte(xtensa_kio_paddr + CA_BYPASS),
			XCHAL_KIO_BYPASS_VADDR + 6);
#endif

	local_flush_tlb_all();

	/* Set rasid register to a known value. */

	set_rasid_register(ASID_INSERT(ASID_USER_FIRST));

	/* Set PTEVADDR special register to the start of the page
	 * table, which is in kernel mappable space (ie. not
	 * statically mapped).  This register's value is undefined on
	 * reset.
	 */
	set_ptevaddr_register(PGTABLE_START);
}