omap iommu: tlb and pagetable primitives

This patch provides:

- iotlb_*()     : iommu tlb operations
- iopgtable_*() : iommu pagetable(twl) operations
- iommu_*()     : the other generic operations

and the entry points to register and acquire iommu object.

Signed-off-by: Hiroshi DOYU <Hiroshi.DOYU@nokia.com>

1 files changed, 996 insertions, 0 deletions

diff --git a/arch/arm/plat-omap/iommu.c b/arch/arm/plat-omap/iommu.c
new file mode 100644
index 000000000000..4cf449fa2cb5
--- /dev/null
+++ b/arch/arm/plat-omap/iommu.c
@@ -0,0 +1,996 @@
+/*
+ * omap iommu: tlb and pagetable primitives
+ *
+ * Copyright (C) 2008-2009 Nokia Corporation
+ *
+ * Written by Hiroshi DOYU <Hiroshi.DOYU@nokia.com>,
+ *		Paul Mundt and Toshihiro Kobayashi
+ *
+ * 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.
+ */
+
+#include <linux/err.h>
+#include <linux/module.h>
+#include <linux/interrupt.h>
+#include <linux/ioport.h>
+#include <linux/clk.h>
+#include <linux/platform_device.h>
+
+#include <asm/cacheflush.h>
+
+#include <mach/iommu.h>
+
+#include "iopgtable.h"
+
+/* accommodate the difference between omap1 and omap2/3 */
+static const struct iommu_functions *arch_iommu;
+
+static struct platform_driver omap_iommu_driver;
+static struct kmem_cache *iopte_cachep;
+
+/**
+ * install_iommu_arch - Install archtecure specific iommu functions
+ * @ops:	a pointer to architecture specific iommu functions
+ *
+ * There are several kind of iommu algorithm(tlb, pagetable) among
+ * omap series. This interface installs such an iommu algorighm.
+ **/
+int install_iommu_arch(const struct iommu_functions *ops)
+{
+	if (arch_iommu)
+		return -EBUSY;
+
+	arch_iommu = ops;
+	return 0;
+}
+EXPORT_SYMBOL_GPL(install_iommu_arch);
+
+/**
+ * uninstall_iommu_arch - Uninstall archtecure specific iommu functions
+ * @ops:	a pointer to architecture specific iommu functions
+ *
+ * This interface uninstalls the iommu algorighm installed previously.
+ **/
+void uninstall_iommu_arch(const struct iommu_functions *ops)
+{
+	if (arch_iommu != ops)
+		pr_err("%s: not your arch\n", __func__);
+
+	arch_iommu = NULL;
+}
+EXPORT_SYMBOL_GPL(uninstall_iommu_arch);
+
+/**
+ * iommu_save_ctx - Save registers for pm off-mode support
+ * @obj:	target iommu
+ **/
+void iommu_save_ctx(struct iommu *obj)
+{
+	arch_iommu->save_ctx(obj);
+}
+EXPORT_SYMBOL_GPL(iommu_save_ctx);
+
+/**
+ * iommu_restore_ctx - Restore registers for pm off-mode support
+ * @obj:	target iommu
+ **/
+void iommu_restore_ctx(struct iommu *obj)
+{
+	arch_iommu->restore_ctx(obj);
+}
+EXPORT_SYMBOL_GPL(iommu_restore_ctx);
+
+/**
+ * iommu_arch_version - Return running iommu arch version
+ **/
+u32 iommu_arch_version(void)
+{
+	return arch_iommu->version;
+}
+EXPORT_SYMBOL_GPL(iommu_arch_version);
+
+static int iommu_enable(struct iommu *obj)
+{
+	int err;
+
+	if (!obj)
+		return -EINVAL;
+
+	clk_enable(obj->clk);
+
+	err = arch_iommu->enable(obj);
+
+	clk_disable(obj->clk);
+	return err;
+}
+
+static void iommu_disable(struct iommu *obj)
+{
+	if (!obj)
+		return;
+
+	clk_enable(obj->clk);
+
+	arch_iommu->disable(obj);
+
+	clk_disable(obj->clk);
+}
+
+/*
+ *	TLB operations
+ */
+void iotlb_cr_to_e(struct cr_regs *cr, struct iotlb_entry *e)
+{
+	BUG_ON(!cr || !e);
+
+	arch_iommu->cr_to_e(cr, e);
+}
+EXPORT_SYMBOL_GPL(iotlb_cr_to_e);
+
+static inline int iotlb_cr_valid(struct cr_regs *cr)
+{
+	if (!cr)
+		return -EINVAL;
+
+	return arch_iommu->cr_valid(cr);
+}
+
+static inline struct cr_regs *iotlb_alloc_cr(struct iommu *obj,
+					     struct iotlb_entry *e)
+{
+	if (!e)
+		return NULL;
+
+	return arch_iommu->alloc_cr(obj, e);
+}
+
+u32 iotlb_cr_to_virt(struct cr_regs *cr)
+{
+	return arch_iommu->cr_to_virt(cr);
+}
+EXPORT_SYMBOL_GPL(iotlb_cr_to_virt);
+
+static u32 get_iopte_attr(struct iotlb_entry *e)
+{
+	return arch_iommu->get_pte_attr(e);
+}
+
+static u32 iommu_report_fault(struct iommu *obj, u32 *da)
+{
+	return arch_iommu->fault_isr(obj, da);
+}
+
+static void iotlb_lock_get(struct iommu *obj, struct iotlb_lock *l)
+{
+	u32 val;
+
+	val = iommu_read_reg(obj, MMU_LOCK);
+
+	l->base = MMU_LOCK_BASE(val);
+	l->vict = MMU_LOCK_VICT(val);
+
+	BUG_ON(l->base != 0); /* Currently no preservation is used */
+}
+
+static void iotlb_lock_set(struct iommu *obj, struct iotlb_lock *l)
+{
+	u32 val;
+
+	BUG_ON(l->base != 0); /* Currently no preservation is used */
+
+	val = (l->base << MMU_LOCK_BASE_SHIFT);
+	val |= (l->vict << MMU_LOCK_VICT_SHIFT);
+
+	iommu_write_reg(obj, val, MMU_LOCK);
+}
+
+static void iotlb_read_cr(struct iommu *obj, struct cr_regs *cr)
+{
+	arch_iommu->tlb_read_cr(obj, cr);
+}
+
+static void iotlb_load_cr(struct iommu *obj, struct cr_regs *cr)
+{
+	arch_iommu->tlb_load_cr(obj, cr);
+
+	iommu_write_reg(obj, 1, MMU_FLUSH_ENTRY);
+	iommu_write_reg(obj, 1, MMU_LD_TLB);
+}
+
+/**
+ * iotlb_dump_cr - Dump an iommu tlb entry into buf
+ * @obj:	target iommu
+ * @cr:		contents of cam and ram register
+ * @buf:	output buffer
+ **/
+static inline ssize_t iotlb_dump_cr(struct iommu *obj, struct cr_regs *cr,
+				    char *buf)
+{
+	BUG_ON(!cr || !buf);
+
+	return arch_iommu->dump_cr(obj, cr, buf);
+}
+
+/**
+ * load_iotlb_entry - Set an iommu tlb entry
+ * @obj:	target iommu
+ * @e:		an iommu tlb entry info
+ **/
+int load_iotlb_entry(struct iommu *obj, struct iotlb_entry *e)
+{
+	int i;
+	int err = 0;
+	struct iotlb_lock l;
+	struct cr_regs *cr;
+
+	if (!obj || !obj->nr_tlb_entries || !e)
+		return -EINVAL;
+
+	clk_enable(obj->clk);
+
+	for (i = 0; i < obj->nr_tlb_entries; i++) {
+		struct cr_regs tmp;
+
+		iotlb_lock_get(obj, &l);
+		l.vict = i;
+		iotlb_lock_set(obj, &l);
+		iotlb_read_cr(obj, &tmp);
+		if (!iotlb_cr_valid(&tmp))
+			break;
+	}
+
+	if (i == obj->nr_tlb_entries) {
+		dev_dbg(obj->dev, "%s: full: no entry\n", __func__);
+		err = -EBUSY;
+		goto out;
+	}
+
+	cr = iotlb_alloc_cr(obj, e);
+	if (IS_ERR(cr)) {
+		clk_disable(obj->clk);
+		return PTR_ERR(cr);
+	}
+
+	iotlb_load_cr(obj, cr);
+	kfree(cr);
+
+	/* increment victim for next tlb load */
+	if (++l.vict == obj->nr_tlb_entries)
+		l.vict = 0;
+	iotlb_lock_set(obj, &l);
+out:
+	clk_disable(obj->clk);
+	return err;
+}
+EXPORT_SYMBOL_GPL(load_iotlb_entry);
+
+/**
+ * flush_iotlb_page - Clear an iommu tlb entry
+ * @obj:	target iommu
+ * @da:		iommu device virtual address
+ *
+ * Clear an iommu tlb entry which includes 'da' address.
+ **/
+void flush_iotlb_page(struct iommu *obj, u32 da)
+{
+	struct iotlb_lock l;
+	int i;
+
+	clk_enable(obj->clk);
+
+	for (i = 0; i < obj->nr_tlb_entries; i++) {
+		struct cr_regs cr;
+		u32 start;
+		size_t bytes;
+
+		iotlb_lock_get(obj, &l);
+		l.vict = i;
+		iotlb_lock_set(obj, &l);
+		iotlb_read_cr(obj, &cr);
+		if (!iotlb_cr_valid(&cr))
+			continue;
+
+		start = iotlb_cr_to_virt(&cr);
+		bytes = iopgsz_to_bytes(cr.cam & 3);
+
+		if ((start <= da) && (da < start + bytes)) {
+			dev_dbg(obj->dev, "%s: %08x<=%08x(%x)\n",
+				__func__, start, da, bytes);
+
+			iommu_write_reg(obj, 1, MMU_FLUSH_ENTRY);
+		}
+	}
+	clk_disable(obj->clk);
+
+	if (i == obj->nr_tlb_entries)
+		dev_dbg(obj->dev, "%s: no page for %08x\n", __func__, da);
+}
+EXPORT_SYMBOL_GPL(flush_iotlb_page);
+
+/**
+ * flush_iotlb_range - Clear an iommu tlb entries
+ * @obj:	target iommu
+ * @start:	iommu device virtual address(start)
+ * @end:	iommu device virtual address(end)
+ *
+ * Clear an iommu tlb entry which includes 'da' address.
+ **/
+void flush_iotlb_range(struct iommu *obj, u32 start, u32 end)
+{
+	u32 da = start;
+
+	while (da < end) {
+		flush_iotlb_page(obj, da);
+		/* FIXME: Optimize for multiple page size */
+		da += IOPTE_SIZE;
+	}
+}
+EXPORT_SYMBOL_GPL(flush_iotlb_range);
+
+/**
+ * flush_iotlb_all - Clear all iommu tlb entries
+ * @obj:	target iommu
+ **/
+void flush_iotlb_all(struct iommu *obj)
+{
+	struct iotlb_lock l;
+
+	clk_enable(obj->clk);
+
+	l.base = 0;
+	l.vict = 0;
+	iotlb_lock_set(obj, &l);
+
+	iommu_write_reg(obj, 1, MMU_GFLUSH);
+
+	clk_disable(obj->clk);
+}
+EXPORT_SYMBOL_GPL(flush_iotlb_all);
+
+#if defined(CONFIG_OMAP_IOMMU_DEBUG_MODULE)
+
+ssize_t iommu_dump_ctx(struct iommu *obj, char *buf)
+{
+	ssize_t bytes;
+
+	if (!obj || !buf)
+		return -EINVAL;
+
+	clk_enable(obj->clk);
+
+	bytes = arch_iommu->dump_ctx(obj, buf);
+
+	clk_disable(obj->clk);
+
+	return bytes;
+}
+EXPORT_SYMBOL_GPL(iommu_dump_ctx);
+
+static int __dump_tlb_entries(struct iommu *obj, struct cr_regs *crs)
+{
+	int i;
+	struct iotlb_lock saved, l;
+	struct cr_regs *p = crs;
+
+	clk_enable(obj->clk);
+
+	iotlb_lock_get(obj, &saved);
+	memcpy(&l, &saved, sizeof(saved));
+
+	for (i = 0; i < obj->nr_tlb_entries; i++) {
+		struct cr_regs tmp;
+
+		iotlb_lock_get(obj, &l);
+		l.vict = i;
+		iotlb_lock_set(obj, &l);
+		iotlb_read_cr(obj, &tmp);
+		if (!iotlb_cr_valid(&tmp))
+			continue;
+
+		*p++ = tmp;
+	}
+	iotlb_lock_set(obj, &saved);
+	clk_disable(obj->clk);
+
+	return  p - crs;
+}
+
+/**
+ * dump_tlb_entries - dump cr arrays to given buffer
+ * @obj:	target iommu
+ * @buf:	output buffer
+ **/
+size_t dump_tlb_entries(struct iommu *obj, char *buf)
+{
+	int i, n;
+	struct cr_regs *cr;
+	char *p = buf;
+
+	cr = kcalloc(obj->nr_tlb_entries, sizeof(*cr), GFP_KERNEL);
+	if (!cr)
+		return 0;
+
+	n = __dump_tlb_entries(obj, cr);
+	for (i = 0; i < n; i++)
+		p += iotlb_dump_cr(obj, cr + i, p);
+	kfree(cr);
+
+	return p - buf;
+}
+EXPORT_SYMBOL_GPL(dump_tlb_entries);
+
+int foreach_iommu_device(void *data, int (*fn)(struct device *, void *))
+{
+	return driver_for_each_device(&omap_iommu_driver.driver,
+				      NULL, data, fn);
+}
+EXPORT_SYMBOL_GPL(foreach_iommu_device);
+
+#endif /* CONFIG_OMAP_IOMMU_DEBUG_MODULE */
+
+/*
+ *	H/W pagetable operations
+ */
+static void flush_iopgd_range(u32 *first, u32 *last)
+{
+	/* FIXME: L2 cache should be taken care of if it exists */
+	do {
+		asm("mcr	p15, 0, %0, c7, c10, 1 @ flush_pgd"
+		    : : "r" (first));
+		first += L1_CACHE_BYTES / sizeof(*first);
+	} while (first <= last);
+}
+
+static void flush_iopte_range(u32 *first, u32 *last)
+{
+	/* FIXME: L2 cache should be taken care of if it exists */
+	do {
+		asm("mcr	p15, 0, %0, c7, c10, 1 @ flush_pte"
+		    : : "r" (first));
+		first += L1_CACHE_BYTES / sizeof(*first);
+	} while (first <= last);
+}
+
+static void iopte_free(u32 *iopte)
+{
+	/* Note: freed iopte's must be clean ready for re-use */
+	kmem_cache_free(iopte_cachep, iopte);
+}
+
+static u32 *iopte_alloc(struct iommu *obj, u32 *iopgd, u32 da)
+{
+	u32 *iopte;
+
+	/* a table has already existed */
+	if (*iopgd)
+		goto pte_ready;
+
+	/*
+	 * do the allocation outside the page table lock
+	 */
+	spin_unlock(&obj->page_table_lock);
+	iopte = kmem_cache_zalloc(iopte_cachep, GFP_KERNEL);
+	spin_lock(&obj->page_table_lock);
+
+	if (!*iopgd) {
+		if (!iopte)
+			return ERR_PTR(-ENOMEM);
+
+		*iopgd = virt_to_phys(iopte) | IOPGD_TABLE;
+		flush_iopgd_range(iopgd, iopgd);
+
+		dev_vdbg(obj->dev, "%s: a new pte:%p\n", __func__, iopte);
+	} else {
+		/* We raced, free the reduniovant table */
+		iopte_free(iopte);
+	}
+
+pte_ready:
+	iopte = iopte_offset(iopgd, da);
+
+	dev_vdbg(obj->dev,
+		 "%s: da:%08x pgd:%p *pgd:%08x pte:%p *pte:%08x\n",
+		 __func__, da, iopgd, *iopgd, iopte, *iopte);
+
+	return iopte;
+}
+
+static int iopgd_alloc_section(struct iommu *obj, u32 da, u32 pa, u32 prot)
+{
+	u32 *iopgd = iopgd_offset(obj, da);
+
+	*iopgd = (pa & IOSECTION_MASK) | prot | IOPGD_SECTION;
+	flush_iopgd_range(iopgd, iopgd);
+	return 0;
+}
+
+static int iopgd_alloc_super(struct iommu *obj, u32 da, u32 pa, u32 prot)
+{
+	u32 *iopgd = iopgd_offset(obj, da);
+	int i;
+
+	for (i = 0; i < 16; i++)
+		*(iopgd + i) = (pa & IOSUPER_MASK) | prot | IOPGD_SUPER;
+	flush_iopgd_range(iopgd, iopgd + 15);
+	return 0;
+}
+
+static int iopte_alloc_page(struct iommu *obj, u32 da, u32 pa, u32 prot)
+{
+	u32 *iopgd = iopgd_offset(obj, da);
+	u32 *iopte = iopte_alloc(obj, iopgd, da);
+
+	if (IS_ERR(iopte))
+		return PTR_ERR(iopte);
+
+	*iopte = (pa & IOPAGE_MASK) | prot | IOPTE_SMALL;
+	flush_iopte_range(iopte, iopte);
+
+	dev_vdbg(obj->dev, "%s: da:%08x pa:%08x pte:%p *pte:%08x\n",
+		 __func__, da, pa, iopte, *iopte);
+
+	return 0;
+}
+
+static int iopte_alloc_large(struct iommu *obj, u32 da, u32 pa, u32 prot)
+{
+	u32 *iopgd = iopgd_offset(obj, da);
+	u32 *iopte = iopte_alloc(obj, iopgd, da);
+	int i;
+
+	if (IS_ERR(iopte))
+		return PTR_ERR(iopte);
+
+	for (i = 0; i < 16; i++)
+		*(iopte + i) = (pa & IOLARGE_MASK) | prot | IOPTE_LARGE;
+	flush_iopte_range(iopte, iopte + 15);
+	return 0;
+}
+
+static int iopgtable_store_entry_core(struct iommu *obj, struct iotlb_entry *e)
+{
+	int (*fn)(struct iommu *, u32, u32, u32);
+	u32 prot;
+	int err;
+
+	if (!obj || !e)
+		return -EINVAL;
+
+	switch (e->pgsz) {
+	case MMU_CAM_PGSZ_16M:
+		fn = iopgd_alloc_super;
+		break;
+	case MMU_CAM_PGSZ_1M:
+		fn = iopgd_alloc_section;
+		break;
+	case MMU_CAM_PGSZ_64K:
+		fn = iopte_alloc_large;
+		break;
+	case MMU_CAM_PGSZ_4K:
+		fn = iopte_alloc_page;
+		break;
+	default:
+		fn = NULL;
+		BUG();
+		break;
+	}
+
+	prot = get_iopte_attr(e);
+
+	spin_lock(&obj->page_table_lock);
+	err = fn(obj, e->da, e->pa, prot);
+	spin_unlock(&obj->page_table_lock);
+
+	return err;
+}
+
+/**
+ * iopgtable_store_entry - Make an iommu pte entry
+ * @obj:	target iommu
+ * @e:		an iommu tlb entry info
+ **/
+int iopgtable_store_entry(struct iommu *obj, struct iotlb_entry *e)
+{
+	int err;
+
+	flush_iotlb_page(obj, e->da);
+	err = iopgtable_store_entry_core(obj, e);
+#ifdef PREFETCH_IOTLB
+	if (!err)
+		load_iotlb_entry(obj, e);
+#endif
+	return err;
+}
+EXPORT_SYMBOL_GPL(iopgtable_store_entry);
+
+/**
+ * iopgtable_lookup_entry - Lookup an iommu pte entry
+ * @obj:	target iommu
+ * @da:		iommu device virtual address
+ * @ppgd:	iommu pgd entry pointer to be returned
+ * @ppte:	iommu pte entry pointer to be returned
+ **/
+void iopgtable_lookup_entry(struct iommu *obj, u32 da, u32 **ppgd, u32 **ppte)
+{
+	u32 *iopgd, *iopte = NULL;
+
+	iopgd = iopgd_offset(obj, da);
+	if (!*iopgd)
+		goto out;
+
+	if (*iopgd & IOPGD_TABLE)
+		iopte = iopte_offset(iopgd, da);
+out:
+	*ppgd = iopgd;
+	*ppte = iopte;
+}
+EXPORT_SYMBOL_GPL(iopgtable_lookup_entry);
+
+static size_t iopgtable_clear_entry_core(struct iommu *obj, u32 da)
+{
+	size_t bytes;
+	u32 *iopgd = iopgd_offset(obj, da);
+	int nent = 1;
+
+	if (!*iopgd)
+		return 0;
+
+	if (*iopgd & IOPGD_TABLE) {
+		int i;
+		u32 *iopte = iopte_offset(iopgd, da);
+
+		bytes = IOPTE_SIZE;
+		if (*iopte & IOPTE_LARGE) {
+			nent *= 16;
+			/* rewind to the 1st entry */
+			iopte = (u32 *)((u32)iopte & IOLARGE_MASK);
+		}
+		bytes *= nent;
+		memset(iopte, 0, nent * sizeof(*iopte));
+		flush_iopte_range(iopte, iopte + (nent - 1) * sizeof(*iopte));
+
+		/*
+		 * do table walk to check if this table is necessary or not
+		 */
+		iopte = iopte_offset(iopgd, 0);
+		for (i = 0; i < PTRS_PER_IOPTE; i++)
+			if (iopte[i])
+				goto out;
+
+		iopte_free(iopte);
+		nent = 1; /* for the next L1 entry */
+	} else {
+		bytes = IOPGD_SIZE;
+		if (*iopgd & IOPGD_SUPER) {
+			nent *= 16;
+			/* rewind to the 1st entry */
+			iopgd = (u32 *)((u32)iopgd & IOSUPER_MASK);
+		}
+		bytes *= nent;
+	}
+	memset(iopgd, 0, nent * sizeof(*iopgd));
+	flush_iopgd_range(iopgd, iopgd + (nent - 1) * sizeof(*iopgd));
+out:
+	return bytes;
+}
+
+/**
+ * iopgtable_clear_entry - Remove an iommu pte entry
+ * @obj:	target iommu
+ * @da:		iommu device virtual address
+ **/
+size_t iopgtable_clear_entry(struct iommu *obj, u32 da)
+{
+	size_t bytes;
+
+	spin_lock(&obj->page_table_lock);
+
+	bytes = iopgtable_clear_entry_core(obj, da);
+	flush_iotlb_page(obj, da);
+
+	spin_unlock(&obj->page_table_lock);
+
+	return bytes;
+}
+EXPORT_SYMBOL_GPL(iopgtable_clear_entry);
+
+static void iopgtable_clear_entry_all(struct iommu *obj)
+{
+	int i;
+
+	spin_lock(&obj->page_table_lock);
+
+	for (i = 0; i < PTRS_PER_IOPGD; i++) {
+		u32 da;
+		u32 *iopgd;
+
+		da = i << IOPGD_SHIFT;
+		iopgd = iopgd_offset(obj, da);
+
+		if (!*iopgd)
+			continue;
+
+		if (*iopgd & IOPGD_TABLE)
+			iopte_free(iopte_offset(iopgd, 0));
+
+		*iopgd = 0;
+		flush_iopgd_range(iopgd, iopgd);
+	}
+
+	flush_iotlb_all(obj);
+
+	spin_unlock(&obj->page_table_lock);
+}
+
+/*
+ *	Device IOMMU generic operations
+ */
+static irqreturn_t iommu_fault_handler(int irq, void *data)
+{
+	u32 stat, da;
+	u32 *iopgd, *iopte;
+	int err = -EIO;
+	struct iommu *obj = data;
+
+	if (!obj->refcount)
+		return IRQ_NONE;
+
+	/* Dynamic loading TLB or PTE */
+	if (obj->isr)
+		err = obj->isr(obj);
+
+	if (!err)
+		return IRQ_HANDLED;
+
+	clk_enable(obj->clk);
+	stat = iommu_report_fault(obj, &da);
+	clk_disable(obj->clk);
+	if (!stat)
+		return IRQ_HANDLED;
+
+	iopgd = iopgd_offset(obj, da);
+
+	if (!(*iopgd & IOPGD_TABLE)) {
+		dev_err(obj->dev, "%s: da:%08x pgd:%p *pgd:%08x\n", __func__,
+			da, iopgd, *iopgd);
+		return IRQ_NONE;
+	}
+
+	iopte = iopte_offset(iopgd, da);
+
+	dev_err(obj->dev, "%s: da:%08x pgd:%p *pgd:%08x pte:%p *pte:%08x\n",
+		__func__, da, iopgd, *iopgd, iopte, *iopte);
+
+	return IRQ_NONE;
+}
+
+static int device_match_by_alias(struct device *dev, void *data)
+{
+	struct iommu *obj = to_iommu(dev);
+	const char *name = data;
+
+	pr_debug("%s: %s %s\n", __func__, obj->name, name);
+
+	return strcmp(obj->name, name) == 0;
+}
+
+/**
+ * iommu_get - Get iommu handler
+ * @name:	target iommu name
+ **/
+struct iommu *iommu_get(const char *name)
+{
+	int err = -ENOMEM;
+	struct device *dev;
+	struct iommu *obj;
+
+	dev = driver_find_device(&omap_iommu_driver.driver, NULL, (void *)name,
+				 device_match_by_alias);
+	if (!dev)
+		return ERR_PTR(-ENODEV);
+
+	obj = to_iommu(dev);
+
+	mutex_lock(&obj->iommu_lock);
+
+	if (obj->refcount++ == 0) {
+		err = iommu_enable(obj);
+		if (err)
+			goto err_enable;
+		flush_iotlb_all(obj);
+	}
+
+	if (!try_module_get(obj->owner))
+		goto err_module;
+
+	mutex_unlock(&obj->iommu_lock);
+
+	dev_dbg(obj->dev, "%s: %s\n", __func__, obj->name);
+	return obj;
+
+err_module:
+	if (obj->refcount == 1)
+		iommu_disable(obj);
+err_enable:
+	obj->refcount--;
+	mutex_unlock(&obj->iommu_lock);
+	return ERR_PTR(err);
+}
+EXPORT_SYMBOL_GPL(iommu_get);
+
+/**
+ * iommu_put - Put back iommu handler
+ * @obj:	target iommu
+ **/
+void iommu_put(struct iommu *obj)
+{
+	if (!obj && IS_ERR(obj))
+		return;
+
+	mutex_lock(&obj->iommu_lock);
+
+	if (--obj->refcount == 0)
+		iommu_disable(obj);
+
+	module_put(obj->owner);
+
+	mutex_unlock(&obj->iommu_lock);
+
+	dev_dbg(obj->dev, "%s: %s\n", __func__, obj->name);
+}
+EXPORT_SYMBOL_GPL(iommu_put);
+
+/*
+ *	OMAP Device MMU(IOMMU) detection
+ */
+static int __devinit omap_iommu_probe(struct platform_device *pdev)
+{
+	int err = -ENODEV;
+	void *p;
+	int irq;
+	struct iommu *obj;
+	struct resource *res;
+	struct iommu_platform_data *pdata = pdev->dev.platform_data;
+
+	if (pdev->num_resources != 2)
+		return -EINVAL;
+
+	obj = kzalloc(sizeof(*obj) + MMU_REG_SIZE, GFP_KERNEL);
+	if (!obj)
+		return -ENOMEM;
+
+	obj->clk = clk_get(&pdev->dev, pdata->clk_name);
+	if (IS_ERR(obj->clk))
+		goto err_clk;
+
+	obj->nr_tlb_entries = pdata->nr_tlb_entries;
+	obj->name = pdata->name;
+	obj->dev = &pdev->dev;
+	obj->ctx = (void *)obj + sizeof(*obj);
+
+	mutex_init(&obj->iommu_lock);
+	mutex_init(&obj->mmap_lock);
+	spin_lock_init(&obj->page_table_lock);
+	INIT_LIST_HEAD(&obj->mmap);
+
+	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+	if (!res) {
+		err = -ENODEV;
+		goto err_mem;
+	}
+	obj->regbase = ioremap(res->start, resource_size(res));
+	if (!obj->regbase) {
+		err = -ENOMEM;
+		goto err_mem;
+	}
+
+	res = request_mem_region(res->start, resource_size(res),
+				 dev_name(&pdev->dev));
+	if (!res) {
+		err = -EIO;
+		goto err_mem;
+	}
+
+	irq = platform_get_irq(pdev, 0);
+	if (irq < 0) {
+		err = -ENODEV;
+		goto err_irq;
+	}
+	err = request_irq(irq, iommu_fault_handler, IRQF_SHARED,
+			  dev_name(&pdev->dev), obj);
+	if (err < 0)
+		goto err_irq;
+	platform_set_drvdata(pdev, obj);
+
+	p = (void *)__get_free_pages(GFP_KERNEL, get_order(IOPGD_TABLE_SIZE));
+	if (!p) {
+		err = -ENOMEM;
+		goto err_pgd;
+	}
+	memset(p, 0, IOPGD_TABLE_SIZE);
+	clean_dcache_area(p, IOPGD_TABLE_SIZE);
+	obj->iopgd = p;
+
+	BUG_ON(!IS_ALIGNED((unsigned long)obj->iopgd, IOPGD_TABLE_SIZE));
+
+	dev_info(&pdev->dev, "%s registered\n", obj->name);
+	return 0;
+
+err_pgd:
+	free_irq(irq, obj);
+err_irq:
+	release_mem_region(res->start, resource_size(res));
+	iounmap(obj->regbase);
+err_mem:
+	clk_put(obj->clk);
+err_clk:
+	kfree(obj);
+	return err;
+}
+
+static int __devexit omap_iommu_remove(struct platform_device *pdev)
+{
+	int irq;
+	struct resource *res;
+	struct iommu *obj = platform_get_drvdata(pdev);
+
+	platform_set_drvdata(pdev, NULL);
+
+	iopgtable_clear_entry_all(obj);
+	free_pages((unsigned long)obj->iopgd, get_order(IOPGD_TABLE_SIZE));
+
+	irq = platform_get_irq(pdev, 0);
+	free_irq(irq, obj);
+	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+	release_mem_region(res->start, resource_size(res));
+	iounmap(obj->regbase);
+
+	clk_put(obj->clk);
+	dev_info(&pdev->dev, "%s removed\n", obj->name);
+	kfree(obj);
+	return 0;
+}
+
+static struct platform_driver omap_iommu_driver = {
+	.probe	= omap_iommu_probe,
+	.remove	= __devexit_p(omap_iommu_remove),
+	.driver	= {
+		.name	= "omap-iommu",
+	},
+};
+
+static void iopte_cachep_ctor(void *iopte)
+{
+	clean_dcache_area(iopte, IOPTE_TABLE_SIZE);
+}
+
+static int __init omap_iommu_init(void)
+{
+	struct kmem_cache *p;
+	const unsigned long flags = SLAB_HWCACHE_ALIGN;
+	size_t align = 1 << 10; /* L2 pagetable alignement */
+
+	p = kmem_cache_create("iopte_cache", IOPTE_TABLE_SIZE, align, flags,
+			      iopte_cachep_ctor);
+	if (!p)
+		return -ENOMEM;
+	iopte_cachep = p;
+
+	return platform_driver_register(&omap_iommu_driver);
+}
+module_init(omap_iommu_init);
+
+static void __exit omap_iommu_exit(void)
+{
+	kmem_cache_destroy(iopte_cachep);
+
+	platform_driver_unregister(&omap_iommu_driver);
+}
+module_exit(omap_iommu_exit);
+
+MODULE_DESCRIPTION("omap iommu: tlb and pagetable primitives");
+MODULE_ALIAS("platform:omap-iommu");
+MODULE_AUTHOR("Hiroshi DOYU, Paul Mundt and Toshihiro Kobayashi");
+MODULE_LICENSE("GPL v2");