Adding upstream version 6.6.15.upstream/6.6.15

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 1160 insertions, 0 deletions

diff --git a/drivers/iommu/tegra-smmu.c b/drivers/iommu/tegra-smmu.c
new file mode 100644
index 000000000..e445f80d0
--- /dev/null
+++ b/drivers/iommu/tegra-smmu.c
@@ -0,0 +1,1160 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Copyright (C) 2011-2014 NVIDIA CORPORATION.  All rights reserved.
+ */
+
+#include <linux/bitops.h>
+#include <linux/debugfs.h>
+#include <linux/err.h>
+#include <linux/iommu.h>
+#include <linux/kernel.h>
+#include <linux/of.h>
+#include <linux/of_platform.h>
+#include <linux/pci.h>
+#include <linux/platform_device.h>
+#include <linux/slab.h>
+#include <linux/spinlock.h>
+#include <linux/dma-mapping.h>
+
+#include <soc/tegra/ahb.h>
+#include <soc/tegra/mc.h>
+
+struct tegra_smmu_group {
+	struct list_head list;
+	struct tegra_smmu *smmu;
+	const struct tegra_smmu_group_soc *soc;
+	struct iommu_group *group;
+	unsigned int swgroup;
+};
+
+struct tegra_smmu {
+	void __iomem *regs;
+	struct device *dev;
+
+	struct tegra_mc *mc;
+	const struct tegra_smmu_soc *soc;
+
+	struct list_head groups;
+
+	unsigned long pfn_mask;
+	unsigned long tlb_mask;
+
+	unsigned long *asids;
+	struct mutex lock;
+
+	struct list_head list;
+
+	struct dentry *debugfs;
+
+	struct iommu_device iommu;	/* IOMMU Core code handle */
+};
+
+struct tegra_smmu_as {
+	struct iommu_domain domain;
+	struct tegra_smmu *smmu;
+	unsigned int use_count;
+	spinlock_t lock;
+	u32 *count;
+	struct page **pts;
+	struct page *pd;
+	dma_addr_t pd_dma;
+	unsigned id;
+	u32 attr;
+};
+
+static struct tegra_smmu_as *to_smmu_as(struct iommu_domain *dom)
+{
+	return container_of(dom, struct tegra_smmu_as, domain);
+}
+
+static inline void smmu_writel(struct tegra_smmu *smmu, u32 value,
+			       unsigned long offset)
+{
+	writel(value, smmu->regs + offset);
+}
+
+static inline u32 smmu_readl(struct tegra_smmu *smmu, unsigned long offset)
+{
+	return readl(smmu->regs + offset);
+}
+
+#define SMMU_CONFIG 0x010
+#define  SMMU_CONFIG_ENABLE (1 << 0)
+
+#define SMMU_TLB_CONFIG 0x14
+#define  SMMU_TLB_CONFIG_HIT_UNDER_MISS (1 << 29)
+#define  SMMU_TLB_CONFIG_ROUND_ROBIN_ARBITRATION (1 << 28)
+#define  SMMU_TLB_CONFIG_ACTIVE_LINES(smmu) \
+	((smmu)->soc->num_tlb_lines & (smmu)->tlb_mask)
+
+#define SMMU_PTC_CONFIG 0x18
+#define  SMMU_PTC_CONFIG_ENABLE (1 << 29)
+#define  SMMU_PTC_CONFIG_REQ_LIMIT(x) (((x) & 0x0f) << 24)
+#define  SMMU_PTC_CONFIG_INDEX_MAP(x) ((x) & 0x3f)
+
+#define SMMU_PTB_ASID 0x01c
+#define  SMMU_PTB_ASID_VALUE(x) ((x) & 0x7f)
+
+#define SMMU_PTB_DATA 0x020
+#define  SMMU_PTB_DATA_VALUE(dma, attr) ((dma) >> 12 | (attr))
+
+#define SMMU_MK_PDE(dma, attr) ((dma) >> SMMU_PTE_SHIFT | (attr))
+
+#define SMMU_TLB_FLUSH 0x030
+#define  SMMU_TLB_FLUSH_VA_MATCH_ALL     (0 << 0)
+#define  SMMU_TLB_FLUSH_VA_MATCH_SECTION (2 << 0)
+#define  SMMU_TLB_FLUSH_VA_MATCH_GROUP   (3 << 0)
+#define  SMMU_TLB_FLUSH_VA_SECTION(addr) ((((addr) & 0xffc00000) >> 12) | \
+					  SMMU_TLB_FLUSH_VA_MATCH_SECTION)
+#define  SMMU_TLB_FLUSH_VA_GROUP(addr)   ((((addr) & 0xffffc000) >> 12) | \
+					  SMMU_TLB_FLUSH_VA_MATCH_GROUP)
+#define  SMMU_TLB_FLUSH_ASID_MATCH       (1 << 31)
+
+#define SMMU_PTC_FLUSH 0x034
+#define  SMMU_PTC_FLUSH_TYPE_ALL (0 << 0)
+#define  SMMU_PTC_FLUSH_TYPE_ADR (1 << 0)
+
+#define SMMU_PTC_FLUSH_HI 0x9b8
+#define  SMMU_PTC_FLUSH_HI_MASK 0x3
+
+/* per-SWGROUP SMMU_*_ASID register */
+#define SMMU_ASID_ENABLE (1 << 31)
+#define SMMU_ASID_MASK 0x7f
+#define SMMU_ASID_VALUE(x) ((x) & SMMU_ASID_MASK)
+
+/* page table definitions */
+#define SMMU_NUM_PDE 1024
+#define SMMU_NUM_PTE 1024
+
+#define SMMU_SIZE_PD (SMMU_NUM_PDE * 4)
+#define SMMU_SIZE_PT (SMMU_NUM_PTE * 4)
+
+#define SMMU_PDE_SHIFT 22
+#define SMMU_PTE_SHIFT 12
+
+#define SMMU_PAGE_MASK		(~(SMMU_SIZE_PT-1))
+#define SMMU_OFFSET_IN_PAGE(x)	((unsigned long)(x) & ~SMMU_PAGE_MASK)
+#define SMMU_PFN_PHYS(x)	((phys_addr_t)(x) << SMMU_PTE_SHIFT)
+#define SMMU_PHYS_PFN(x)	((unsigned long)((x) >> SMMU_PTE_SHIFT))
+
+#define SMMU_PD_READABLE	(1 << 31)
+#define SMMU_PD_WRITABLE	(1 << 30)
+#define SMMU_PD_NONSECURE	(1 << 29)
+
+#define SMMU_PDE_READABLE	(1 << 31)
+#define SMMU_PDE_WRITABLE	(1 << 30)
+#define SMMU_PDE_NONSECURE	(1 << 29)
+#define SMMU_PDE_NEXT		(1 << 28)
+
+#define SMMU_PTE_READABLE	(1 << 31)
+#define SMMU_PTE_WRITABLE	(1 << 30)
+#define SMMU_PTE_NONSECURE	(1 << 29)
+
+#define SMMU_PDE_ATTR		(SMMU_PDE_READABLE | SMMU_PDE_WRITABLE | \
+				 SMMU_PDE_NONSECURE)
+
+static unsigned int iova_pd_index(unsigned long iova)
+{
+	return (iova >> SMMU_PDE_SHIFT) & (SMMU_NUM_PDE - 1);
+}
+
+static unsigned int iova_pt_index(unsigned long iova)
+{
+	return (iova >> SMMU_PTE_SHIFT) & (SMMU_NUM_PTE - 1);
+}
+
+static bool smmu_dma_addr_valid(struct tegra_smmu *smmu, dma_addr_t addr)
+{
+	addr >>= 12;
+	return (addr & smmu->pfn_mask) == addr;
+}
+
+static dma_addr_t smmu_pde_to_dma(struct tegra_smmu *smmu, u32 pde)
+{
+	return (dma_addr_t)(pde & smmu->pfn_mask) << 12;
+}
+
+static void smmu_flush_ptc_all(struct tegra_smmu *smmu)
+{
+	smmu_writel(smmu, SMMU_PTC_FLUSH_TYPE_ALL, SMMU_PTC_FLUSH);
+}
+
+static inline void smmu_flush_ptc(struct tegra_smmu *smmu, dma_addr_t dma,
+				  unsigned long offset)
+{
+	u32 value;
+
+	offset &= ~(smmu->mc->soc->atom_size - 1);
+
+	if (smmu->mc->soc->num_address_bits > 32) {
+#ifdef CONFIG_ARCH_DMA_ADDR_T_64BIT
+		value = (dma >> 32) & SMMU_PTC_FLUSH_HI_MASK;
+#else
+		value = 0;
+#endif
+		smmu_writel(smmu, value, SMMU_PTC_FLUSH_HI);
+	}
+
+	value = (dma + offset) | SMMU_PTC_FLUSH_TYPE_ADR;
+	smmu_writel(smmu, value, SMMU_PTC_FLUSH);
+}
+
+static inline void smmu_flush_tlb(struct tegra_smmu *smmu)
+{
+	smmu_writel(smmu, SMMU_TLB_FLUSH_VA_MATCH_ALL, SMMU_TLB_FLUSH);
+}
+
+static inline void smmu_flush_tlb_asid(struct tegra_smmu *smmu,
+				       unsigned long asid)
+{
+	u32 value;
+
+	if (smmu->soc->num_asids == 4)
+		value = (asid & 0x3) << 29;
+	else
+		value = (asid & 0x7f) << 24;
+
+	value |= SMMU_TLB_FLUSH_ASID_MATCH | SMMU_TLB_FLUSH_VA_MATCH_ALL;
+	smmu_writel(smmu, value, SMMU_TLB_FLUSH);
+}
+
+static inline void smmu_flush_tlb_section(struct tegra_smmu *smmu,
+					  unsigned long asid,
+					  unsigned long iova)
+{
+	u32 value;
+
+	if (smmu->soc->num_asids == 4)
+		value = (asid & 0x3) << 29;
+	else
+		value = (asid & 0x7f) << 24;
+
+	value |= SMMU_TLB_FLUSH_ASID_MATCH | SMMU_TLB_FLUSH_VA_SECTION(iova);
+	smmu_writel(smmu, value, SMMU_TLB_FLUSH);
+}
+
+static inline void smmu_flush_tlb_group(struct tegra_smmu *smmu,
+					unsigned long asid,
+					unsigned long iova)
+{
+	u32 value;
+
+	if (smmu->soc->num_asids == 4)
+		value = (asid & 0x3) << 29;
+	else
+		value = (asid & 0x7f) << 24;
+
+	value |= SMMU_TLB_FLUSH_ASID_MATCH | SMMU_TLB_FLUSH_VA_GROUP(iova);
+	smmu_writel(smmu, value, SMMU_TLB_FLUSH);
+}
+
+static inline void smmu_flush(struct tegra_smmu *smmu)
+{
+	smmu_readl(smmu, SMMU_PTB_ASID);
+}
+
+static int tegra_smmu_alloc_asid(struct tegra_smmu *smmu, unsigned int *idp)
+{
+	unsigned long id;
+
+	id = find_first_zero_bit(smmu->asids, smmu->soc->num_asids);
+	if (id >= smmu->soc->num_asids)
+		return -ENOSPC;
+
+	set_bit(id, smmu->asids);
+	*idp = id;
+
+	return 0;
+}
+
+static void tegra_smmu_free_asid(struct tegra_smmu *smmu, unsigned int id)
+{
+	clear_bit(id, smmu->asids);
+}
+
+static struct iommu_domain *tegra_smmu_domain_alloc(unsigned type)
+{
+	struct tegra_smmu_as *as;
+
+	if (type != IOMMU_DOMAIN_UNMANAGED)
+		return NULL;
+
+	as = kzalloc(sizeof(*as), GFP_KERNEL);
+	if (!as)
+		return NULL;
+
+	as->attr = SMMU_PD_READABLE | SMMU_PD_WRITABLE | SMMU_PD_NONSECURE;
+
+	as->pd = alloc_page(GFP_KERNEL | __GFP_DMA | __GFP_ZERO);
+	if (!as->pd) {
+		kfree(as);
+		return NULL;
+	}
+
+	as->count = kcalloc(SMMU_NUM_PDE, sizeof(u32), GFP_KERNEL);
+	if (!as->count) {
+		__free_page(as->pd);
+		kfree(as);
+		return NULL;
+	}
+
+	as->pts = kcalloc(SMMU_NUM_PDE, sizeof(*as->pts), GFP_KERNEL);
+	if (!as->pts) {
+		kfree(as->count);
+		__free_page(as->pd);
+		kfree(as);
+		return NULL;
+	}
+
+	spin_lock_init(&as->lock);
+
+	/* setup aperture */
+	as->domain.geometry.aperture_start = 0;
+	as->domain.geometry.aperture_end = 0xffffffff;
+	as->domain.geometry.force_aperture = true;
+
+	return &as->domain;
+}
+
+static void tegra_smmu_domain_free(struct iommu_domain *domain)
+{
+	struct tegra_smmu_as *as = to_smmu_as(domain);
+
+	/* TODO: free page directory and page tables */
+
+	WARN_ON_ONCE(as->use_count);
+	kfree(as->count);
+	kfree(as->pts);
+	kfree(as);
+}
+
+static const struct tegra_smmu_swgroup *
+tegra_smmu_find_swgroup(struct tegra_smmu *smmu, unsigned int swgroup)
+{
+	const struct tegra_smmu_swgroup *group = NULL;
+	unsigned int i;
+
+	for (i = 0; i < smmu->soc->num_swgroups; i++) {
+		if (smmu->soc->swgroups[i].swgroup == swgroup) {
+			group = &smmu->soc->swgroups[i];
+			break;
+		}
+	}
+
+	return group;
+}
+
+static void tegra_smmu_enable(struct tegra_smmu *smmu, unsigned int swgroup,
+			      unsigned int asid)
+{
+	const struct tegra_smmu_swgroup *group;
+	unsigned int i;
+	u32 value;
+
+	group = tegra_smmu_find_swgroup(smmu, swgroup);
+	if (group) {
+		value = smmu_readl(smmu, group->reg);
+		value &= ~SMMU_ASID_MASK;
+		value |= SMMU_ASID_VALUE(asid);
+		value |= SMMU_ASID_ENABLE;
+		smmu_writel(smmu, value, group->reg);
+	} else {
+		pr_warn("%s group from swgroup %u not found\n", __func__,
+				swgroup);
+		/* No point moving ahead if group was not found */
+		return;
+	}
+
+	for (i = 0; i < smmu->soc->num_clients; i++) {
+		const struct tegra_mc_client *client = &smmu->soc->clients[i];
+
+		if (client->swgroup != swgroup)
+			continue;
+
+		value = smmu_readl(smmu, client->regs.smmu.reg);
+		value |= BIT(client->regs.smmu.bit);
+		smmu_writel(smmu, value, client->regs.smmu.reg);
+	}
+}
+
+static void tegra_smmu_disable(struct tegra_smmu *smmu, unsigned int swgroup,
+			       unsigned int asid)
+{
+	const struct tegra_smmu_swgroup *group;
+	unsigned int i;
+	u32 value;
+
+	group = tegra_smmu_find_swgroup(smmu, swgroup);
+	if (group) {
+		value = smmu_readl(smmu, group->reg);
+		value &= ~SMMU_ASID_MASK;
+		value |= SMMU_ASID_VALUE(asid);
+		value &= ~SMMU_ASID_ENABLE;
+		smmu_writel(smmu, value, group->reg);
+	}
+
+	for (i = 0; i < smmu->soc->num_clients; i++) {
+		const struct tegra_mc_client *client = &smmu->soc->clients[i];
+
+		if (client->swgroup != swgroup)
+			continue;
+
+		value = smmu_readl(smmu, client->regs.smmu.reg);
+		value &= ~BIT(client->regs.smmu.bit);
+		smmu_writel(smmu, value, client->regs.smmu.reg);
+	}
+}
+
+static int tegra_smmu_as_prepare(struct tegra_smmu *smmu,
+				 struct tegra_smmu_as *as)
+{
+	u32 value;
+	int err = 0;
+
+	mutex_lock(&smmu->lock);
+
+	if (as->use_count > 0) {
+		as->use_count++;
+		goto unlock;
+	}
+
+	as->pd_dma = dma_map_page(smmu->dev, as->pd, 0, SMMU_SIZE_PD,
+				  DMA_TO_DEVICE);
+	if (dma_mapping_error(smmu->dev, as->pd_dma)) {
+		err = -ENOMEM;
+		goto unlock;
+	}
+
+	/* We can't handle 64-bit DMA addresses */
+	if (!smmu_dma_addr_valid(smmu, as->pd_dma)) {
+		err = -ENOMEM;
+		goto err_unmap;
+	}
+
+	err = tegra_smmu_alloc_asid(smmu, &as->id);
+	if (err < 0)
+		goto err_unmap;
+
+	smmu_flush_ptc(smmu, as->pd_dma, 0);
+	smmu_flush_tlb_asid(smmu, as->id);
+
+	smmu_writel(smmu, as->id & 0x7f, SMMU_PTB_ASID);
+	value = SMMU_PTB_DATA_VALUE(as->pd_dma, as->attr);
+	smmu_writel(smmu, value, SMMU_PTB_DATA);
+	smmu_flush(smmu);
+
+	as->smmu = smmu;
+	as->use_count++;
+
+	mutex_unlock(&smmu->lock);
+
+	return 0;
+
+err_unmap:
+	dma_unmap_page(smmu->dev, as->pd_dma, SMMU_SIZE_PD, DMA_TO_DEVICE);
+unlock:
+	mutex_unlock(&smmu->lock);
+
+	return err;
+}
+
+static void tegra_smmu_as_unprepare(struct tegra_smmu *smmu,
+				    struct tegra_smmu_as *as)
+{
+	mutex_lock(&smmu->lock);
+
+	if (--as->use_count > 0) {
+		mutex_unlock(&smmu->lock);
+		return;
+	}
+
+	tegra_smmu_free_asid(smmu, as->id);
+
+	dma_unmap_page(smmu->dev, as->pd_dma, SMMU_SIZE_PD, DMA_TO_DEVICE);
+
+	as->smmu = NULL;
+
+	mutex_unlock(&smmu->lock);
+}
+
+static int tegra_smmu_attach_dev(struct iommu_domain *domain,
+				 struct device *dev)
+{
+	struct iommu_fwspec *fwspec = dev_iommu_fwspec_get(dev);
+	struct tegra_smmu *smmu = dev_iommu_priv_get(dev);
+	struct tegra_smmu_as *as = to_smmu_as(domain);
+	unsigned int index;
+	int err;
+
+	if (!fwspec)
+		return -ENOENT;
+
+	for (index = 0; index < fwspec->num_ids; index++) {
+		err = tegra_smmu_as_prepare(smmu, as);
+		if (err)
+			goto disable;
+
+		tegra_smmu_enable(smmu, fwspec->ids[index], as->id);
+	}
+
+	if (index == 0)
+		return -ENODEV;
+
+	return 0;
+
+disable:
+	while (index--) {
+		tegra_smmu_disable(smmu, fwspec->ids[index], as->id);
+		tegra_smmu_as_unprepare(smmu, as);
+	}
+
+	return err;
+}
+
+static void tegra_smmu_set_platform_dma(struct device *dev)
+{
+	struct iommu_domain *domain = iommu_get_domain_for_dev(dev);
+	struct iommu_fwspec *fwspec = dev_iommu_fwspec_get(dev);
+	struct tegra_smmu_as *as = to_smmu_as(domain);
+	struct tegra_smmu *smmu = as->smmu;
+	unsigned int index;
+
+	if (!fwspec)
+		return;
+
+	for (index = 0; index < fwspec->num_ids; index++) {
+		tegra_smmu_disable(smmu, fwspec->ids[index], as->id);
+		tegra_smmu_as_unprepare(smmu, as);
+	}
+}
+
+static void tegra_smmu_set_pde(struct tegra_smmu_as *as, unsigned long iova,
+			       u32 value)
+{
+	unsigned int pd_index = iova_pd_index(iova);
+	struct tegra_smmu *smmu = as->smmu;
+	u32 *pd = page_address(as->pd);
+	unsigned long offset = pd_index * sizeof(*pd);
+
+	/* Set the page directory entry first */
+	pd[pd_index] = value;
+
+	/* The flush the page directory entry from caches */
+	dma_sync_single_range_for_device(smmu->dev, as->pd_dma, offset,
+					 sizeof(*pd), DMA_TO_DEVICE);
+
+	/* And flush the iommu */
+	smmu_flush_ptc(smmu, as->pd_dma, offset);
+	smmu_flush_tlb_section(smmu, as->id, iova);
+	smmu_flush(smmu);
+}
+
+static u32 *tegra_smmu_pte_offset(struct page *pt_page, unsigned long iova)
+{
+	u32 *pt = page_address(pt_page);
+
+	return pt + iova_pt_index(iova);
+}
+
+static u32 *tegra_smmu_pte_lookup(struct tegra_smmu_as *as, unsigned long iova,
+				  dma_addr_t *dmap)
+{
+	unsigned int pd_index = iova_pd_index(iova);
+	struct tegra_smmu *smmu = as->smmu;
+	struct page *pt_page;
+	u32 *pd;
+
+	pt_page = as->pts[pd_index];
+	if (!pt_page)
+		return NULL;
+
+	pd = page_address(as->pd);
+	*dmap = smmu_pde_to_dma(smmu, pd[pd_index]);
+
+	return tegra_smmu_pte_offset(pt_page, iova);
+}
+
+static u32 *as_get_pte(struct tegra_smmu_as *as, dma_addr_t iova,
+		       dma_addr_t *dmap, struct page *page)
+{
+	unsigned int pde = iova_pd_index(iova);
+	struct tegra_smmu *smmu = as->smmu;
+
+	if (!as->pts[pde]) {
+		dma_addr_t dma;
+
+		dma = dma_map_page(smmu->dev, page, 0, SMMU_SIZE_PT,
+				   DMA_TO_DEVICE);
+		if (dma_mapping_error(smmu->dev, dma)) {
+			__free_page(page);
+			return NULL;
+		}
+
+		if (!smmu_dma_addr_valid(smmu, dma)) {
+			dma_unmap_page(smmu->dev, dma, SMMU_SIZE_PT,
+				       DMA_TO_DEVICE);
+			__free_page(page);
+			return NULL;
+		}
+
+		as->pts[pde] = page;
+
+		tegra_smmu_set_pde(as, iova, SMMU_MK_PDE(dma, SMMU_PDE_ATTR |
+							      SMMU_PDE_NEXT));
+
+		*dmap = dma;
+	} else {
+		u32 *pd = page_address(as->pd);
+
+		*dmap = smmu_pde_to_dma(smmu, pd[pde]);
+	}
+
+	return tegra_smmu_pte_offset(as->pts[pde], iova);
+}
+
+static void tegra_smmu_pte_get_use(struct tegra_smmu_as *as, unsigned long iova)
+{
+	unsigned int pd_index = iova_pd_index(iova);
+
+	as->count[pd_index]++;
+}
+
+static void tegra_smmu_pte_put_use(struct tegra_smmu_as *as, unsigned long iova)
+{
+	unsigned int pde = iova_pd_index(iova);
+	struct page *page = as->pts[pde];
+
+	/*
+	 * When no entries in this page table are used anymore, return the
+	 * memory page to the system.
+	 */
+	if (--as->count[pde] == 0) {
+		struct tegra_smmu *smmu = as->smmu;
+		u32 *pd = page_address(as->pd);
+		dma_addr_t pte_dma = smmu_pde_to_dma(smmu, pd[pde]);
+
+		tegra_smmu_set_pde(as, iova, 0);
+
+		dma_unmap_page(smmu->dev, pte_dma, SMMU_SIZE_PT, DMA_TO_DEVICE);
+		__free_page(page);
+		as->pts[pde] = NULL;
+	}
+}
+
+static void tegra_smmu_set_pte(struct tegra_smmu_as *as, unsigned long iova,
+			       u32 *pte, dma_addr_t pte_dma, u32 val)
+{
+	struct tegra_smmu *smmu = as->smmu;
+	unsigned long offset = SMMU_OFFSET_IN_PAGE(pte);
+
+	*pte = val;
+
+	dma_sync_single_range_for_device(smmu->dev, pte_dma, offset,
+					 4, DMA_TO_DEVICE);
+	smmu_flush_ptc(smmu, pte_dma, offset);
+	smmu_flush_tlb_group(smmu, as->id, iova);
+	smmu_flush(smmu);
+}
+
+static struct page *as_get_pde_page(struct tegra_smmu_as *as,
+				    unsigned long iova, gfp_t gfp,
+				    unsigned long *flags)
+{
+	unsigned int pde = iova_pd_index(iova);
+	struct page *page = as->pts[pde];
+
+	/* at first check whether allocation needs to be done at all */
+	if (page)
+		return page;
+
+	/*
+	 * In order to prevent exhaustion of the atomic memory pool, we
+	 * allocate page in a sleeping context if GFP flags permit. Hence
+	 * spinlock needs to be unlocked and re-locked after allocation.
+	 */
+	if (gfpflags_allow_blocking(gfp))
+		spin_unlock_irqrestore(&as->lock, *flags);
+
+	page = alloc_page(gfp | __GFP_DMA | __GFP_ZERO);
+
+	if (gfpflags_allow_blocking(gfp))
+		spin_lock_irqsave(&as->lock, *flags);
+
+	/*
+	 * In a case of blocking allocation, a concurrent mapping may win
+	 * the PDE allocation. In this case the allocated page isn't needed
+	 * if allocation succeeded and the allocation failure isn't fatal.
+	 */
+	if (as->pts[pde]) {
+		if (page)
+			__free_page(page);
+
+		page = as->pts[pde];
+	}
+
+	return page;
+}
+
+static int
+__tegra_smmu_map(struct iommu_domain *domain, unsigned long iova,
+		 phys_addr_t paddr, size_t size, int prot, gfp_t gfp,
+		 unsigned long *flags)
+{
+	struct tegra_smmu_as *as = to_smmu_as(domain);
+	dma_addr_t pte_dma;
+	struct page *page;
+	u32 pte_attrs;
+	u32 *pte;
+
+	page = as_get_pde_page(as, iova, gfp, flags);
+	if (!page)
+		return -ENOMEM;
+
+	pte = as_get_pte(as, iova, &pte_dma, page);
+	if (!pte)
+		return -ENOMEM;
+
+	/* If we aren't overwriting a pre-existing entry, increment use */
+	if (*pte == 0)
+		tegra_smmu_pte_get_use(as, iova);
+
+	pte_attrs = SMMU_PTE_NONSECURE;
+
+	if (prot & IOMMU_READ)
+		pte_attrs |= SMMU_PTE_READABLE;
+
+	if (prot & IOMMU_WRITE)
+		pte_attrs |= SMMU_PTE_WRITABLE;
+
+	tegra_smmu_set_pte(as, iova, pte, pte_dma,
+			   SMMU_PHYS_PFN(paddr) | pte_attrs);
+
+	return 0;
+}
+
+static size_t
+__tegra_smmu_unmap(struct iommu_domain *domain, unsigned long iova,
+		   size_t size, struct iommu_iotlb_gather *gather)
+{
+	struct tegra_smmu_as *as = to_smmu_as(domain);
+	dma_addr_t pte_dma;
+	u32 *pte;
+
+	pte = tegra_smmu_pte_lookup(as, iova, &pte_dma);
+	if (!pte || !*pte)
+		return 0;
+
+	tegra_smmu_set_pte(as, iova, pte, pte_dma, 0);
+	tegra_smmu_pte_put_use(as, iova);
+
+	return size;
+}
+
+static int tegra_smmu_map(struct iommu_domain *domain, unsigned long iova,
+			  phys_addr_t paddr, size_t size, int prot, gfp_t gfp)
+{
+	struct tegra_smmu_as *as = to_smmu_as(domain);
+	unsigned long flags;
+	int ret;
+
+	spin_lock_irqsave(&as->lock, flags);
+	ret = __tegra_smmu_map(domain, iova, paddr, size, prot, gfp, &flags);
+	spin_unlock_irqrestore(&as->lock, flags);
+
+	return ret;
+}
+
+static size_t tegra_smmu_unmap(struct iommu_domain *domain, unsigned long iova,
+			       size_t size, struct iommu_iotlb_gather *gather)
+{
+	struct tegra_smmu_as *as = to_smmu_as(domain);
+	unsigned long flags;
+
+	spin_lock_irqsave(&as->lock, flags);
+	size = __tegra_smmu_unmap(domain, iova, size, gather);
+	spin_unlock_irqrestore(&as->lock, flags);
+
+	return size;
+}
+
+static phys_addr_t tegra_smmu_iova_to_phys(struct iommu_domain *domain,
+					   dma_addr_t iova)
+{
+	struct tegra_smmu_as *as = to_smmu_as(domain);
+	unsigned long pfn;
+	dma_addr_t pte_dma;
+	u32 *pte;
+
+	pte = tegra_smmu_pte_lookup(as, iova, &pte_dma);
+	if (!pte || !*pte)
+		return 0;
+
+	pfn = *pte & as->smmu->pfn_mask;
+
+	return SMMU_PFN_PHYS(pfn) + SMMU_OFFSET_IN_PAGE(iova);
+}
+
+static struct tegra_smmu *tegra_smmu_find(struct device_node *np)
+{
+	struct platform_device *pdev;
+	struct tegra_mc *mc;
+
+	pdev = of_find_device_by_node(np);
+	if (!pdev)
+		return NULL;
+
+	mc = platform_get_drvdata(pdev);
+	if (!mc) {
+		put_device(&pdev->dev);
+		return NULL;
+	}
+
+	return mc->smmu;
+}
+
+static int tegra_smmu_configure(struct tegra_smmu *smmu, struct device *dev,
+				struct of_phandle_args *args)
+{
+	const struct iommu_ops *ops = smmu->iommu.ops;
+	int err;
+
+	err = iommu_fwspec_init(dev, &dev->of_node->fwnode, ops);
+	if (err < 0) {
+		dev_err(dev, "failed to initialize fwspec: %d\n", err);
+		return err;
+	}
+
+	err = ops->of_xlate(dev, args);
+	if (err < 0) {
+		dev_err(dev, "failed to parse SW group ID: %d\n", err);
+		iommu_fwspec_free(dev);
+		return err;
+	}
+
+	return 0;
+}
+
+static struct iommu_device *tegra_smmu_probe_device(struct device *dev)
+{
+	struct device_node *np = dev->of_node;
+	struct tegra_smmu *smmu = NULL;
+	struct of_phandle_args args;
+	unsigned int index = 0;
+	int err;
+
+	while (of_parse_phandle_with_args(np, "iommus", "#iommu-cells", index,
+					  &args) == 0) {
+		smmu = tegra_smmu_find(args.np);
+		if (smmu) {
+			err = tegra_smmu_configure(smmu, dev, &args);
+
+			if (err < 0) {
+				of_node_put(args.np);
+				return ERR_PTR(err);
+			}
+		}
+
+		of_node_put(args.np);
+		index++;
+	}
+
+	smmu = dev_iommu_priv_get(dev);
+	if (!smmu)
+		return ERR_PTR(-ENODEV);
+
+	return &smmu->iommu;
+}
+
+static const struct tegra_smmu_group_soc *
+tegra_smmu_find_group(struct tegra_smmu *smmu, unsigned int swgroup)
+{
+	unsigned int i, j;
+
+	for (i = 0; i < smmu->soc->num_groups; i++)
+		for (j = 0; j < smmu->soc->groups[i].num_swgroups; j++)
+			if (smmu->soc->groups[i].swgroups[j] == swgroup)
+				return &smmu->soc->groups[i];
+
+	return NULL;
+}
+
+static void tegra_smmu_group_release(void *iommu_data)
+{
+	struct tegra_smmu_group *group = iommu_data;
+	struct tegra_smmu *smmu = group->smmu;
+
+	mutex_lock(&smmu->lock);
+	list_del(&group->list);
+	mutex_unlock(&smmu->lock);
+}
+
+static struct iommu_group *tegra_smmu_device_group(struct device *dev)
+{
+	struct iommu_fwspec *fwspec = dev_iommu_fwspec_get(dev);
+	struct tegra_smmu *smmu = dev_iommu_priv_get(dev);
+	const struct tegra_smmu_group_soc *soc;
+	unsigned int swgroup = fwspec->ids[0];
+	struct tegra_smmu_group *group;
+	struct iommu_group *grp;
+
+	/* Find group_soc associating with swgroup */
+	soc = tegra_smmu_find_group(smmu, swgroup);
+
+	mutex_lock(&smmu->lock);
+
+	/* Find existing iommu_group associating with swgroup or group_soc */
+	list_for_each_entry(group, &smmu->groups, list)
+		if ((group->swgroup == swgroup) || (soc && group->soc == soc)) {
+			grp = iommu_group_ref_get(group->group);
+			mutex_unlock(&smmu->lock);
+			return grp;
+		}
+
+	group = devm_kzalloc(smmu->dev, sizeof(*group), GFP_KERNEL);
+	if (!group) {
+		mutex_unlock(&smmu->lock);
+		return NULL;
+	}
+
+	INIT_LIST_HEAD(&group->list);
+	group->swgroup = swgroup;
+	group->smmu = smmu;
+	group->soc = soc;
+
+	if (dev_is_pci(dev))
+		group->group = pci_device_group(dev);
+	else
+		group->group = generic_device_group(dev);
+
+	if (IS_ERR(group->group)) {
+		devm_kfree(smmu->dev, group);
+		mutex_unlock(&smmu->lock);
+		return NULL;
+	}
+
+	iommu_group_set_iommudata(group->group, group, tegra_smmu_group_release);
+	if (soc)
+		iommu_group_set_name(group->group, soc->name);
+	list_add_tail(&group->list, &smmu->groups);
+	mutex_unlock(&smmu->lock);
+
+	return group->group;
+}
+
+static int tegra_smmu_of_xlate(struct device *dev,
+			       struct of_phandle_args *args)
+{
+	struct platform_device *iommu_pdev = of_find_device_by_node(args->np);
+	struct tegra_mc *mc = platform_get_drvdata(iommu_pdev);
+	u32 id = args->args[0];
+
+	/*
+	 * Note: we are here releasing the reference of &iommu_pdev->dev, which
+	 * is mc->dev. Although some functions in tegra_smmu_ops may keep using
+	 * its private data beyond this point, it's still safe to do so because
+	 * the SMMU parent device is the same as the MC, so the reference count
+	 * isn't strictly necessary.
+	 */
+	put_device(&iommu_pdev->dev);
+
+	dev_iommu_priv_set(dev, mc->smmu);
+
+	return iommu_fwspec_add_ids(dev, &id, 1);
+}
+
+static const struct iommu_ops tegra_smmu_ops = {
+	.domain_alloc = tegra_smmu_domain_alloc,
+	.probe_device = tegra_smmu_probe_device,
+	.device_group = tegra_smmu_device_group,
+	.set_platform_dma_ops = tegra_smmu_set_platform_dma,
+	.of_xlate = tegra_smmu_of_xlate,
+	.pgsize_bitmap = SZ_4K,
+	.default_domain_ops = &(const struct iommu_domain_ops) {
+		.attach_dev	= tegra_smmu_attach_dev,
+		.map		= tegra_smmu_map,
+		.unmap		= tegra_smmu_unmap,
+		.iova_to_phys	= tegra_smmu_iova_to_phys,
+		.free		= tegra_smmu_domain_free,
+	}
+};
+
+static void tegra_smmu_ahb_enable(void)
+{
+	static const struct of_device_id ahb_match[] = {
+		{ .compatible = "nvidia,tegra30-ahb", },
+		{ }
+	};
+	struct device_node *ahb;
+
+	ahb = of_find_matching_node(NULL, ahb_match);
+	if (ahb) {
+		tegra_ahb_enable_smmu(ahb);
+		of_node_put(ahb);
+	}
+}
+
+static int tegra_smmu_swgroups_show(struct seq_file *s, void *data)
+{
+	struct tegra_smmu *smmu = s->private;
+	unsigned int i;
+	u32 value;
+
+	seq_printf(s, "swgroup    enabled  ASID\n");
+	seq_printf(s, "------------------------\n");
+
+	for (i = 0; i < smmu->soc->num_swgroups; i++) {
+		const struct tegra_smmu_swgroup *group = &smmu->soc->swgroups[i];
+		const char *status;
+		unsigned int asid;
+
+		value = smmu_readl(smmu, group->reg);
+
+		if (value & SMMU_ASID_ENABLE)
+			status = "yes";
+		else
+			status = "no";
+
+		asid = value & SMMU_ASID_MASK;
+
+		seq_printf(s, "%-9s  %-7s  %#04x\n", group->name, status,
+			   asid);
+	}
+
+	return 0;
+}
+
+DEFINE_SHOW_ATTRIBUTE(tegra_smmu_swgroups);
+
+static int tegra_smmu_clients_show(struct seq_file *s, void *data)
+{
+	struct tegra_smmu *smmu = s->private;
+	unsigned int i;
+	u32 value;
+
+	seq_printf(s, "client       enabled\n");
+	seq_printf(s, "--------------------\n");
+
+	for (i = 0; i < smmu->soc->num_clients; i++) {
+		const struct tegra_mc_client *client = &smmu->soc->clients[i];
+		const char *status;
+
+		value = smmu_readl(smmu, client->regs.smmu.reg);
+
+		if (value & BIT(client->regs.smmu.bit))
+			status = "yes";
+		else
+			status = "no";
+
+		seq_printf(s, "%-12s %s\n", client->name, status);
+	}
+
+	return 0;
+}
+
+DEFINE_SHOW_ATTRIBUTE(tegra_smmu_clients);
+
+static void tegra_smmu_debugfs_init(struct tegra_smmu *smmu)
+{
+	smmu->debugfs = debugfs_create_dir("smmu", NULL);
+	if (!smmu->debugfs)
+		return;
+
+	debugfs_create_file("swgroups", S_IRUGO, smmu->debugfs, smmu,
+			    &tegra_smmu_swgroups_fops);
+	debugfs_create_file("clients", S_IRUGO, smmu->debugfs, smmu,
+			    &tegra_smmu_clients_fops);
+}
+
+static void tegra_smmu_debugfs_exit(struct tegra_smmu *smmu)
+{
+	debugfs_remove_recursive(smmu->debugfs);
+}
+
+struct tegra_smmu *tegra_smmu_probe(struct device *dev,
+				    const struct tegra_smmu_soc *soc,
+				    struct tegra_mc *mc)
+{
+	struct tegra_smmu *smmu;
+	u32 value;
+	int err;
+
+	smmu = devm_kzalloc(dev, sizeof(*smmu), GFP_KERNEL);
+	if (!smmu)
+		return ERR_PTR(-ENOMEM);
+
+	/*
+	 * This is a bit of a hack. Ideally we'd want to simply return this
+	 * value. However iommu_device_register() will attempt to add
+	 * all devices to the IOMMU before we get that far. In order
+	 * not to rely on global variables to track the IOMMU instance, we
+	 * set it here so that it can be looked up from the .probe_device()
+	 * callback via the IOMMU device's .drvdata field.
+	 */
+	mc->smmu = smmu;
+
+	smmu->asids = devm_bitmap_zalloc(dev, soc->num_asids, GFP_KERNEL);
+	if (!smmu->asids)
+		return ERR_PTR(-ENOMEM);
+
+	INIT_LIST_HEAD(&smmu->groups);
+	mutex_init(&smmu->lock);
+
+	smmu->regs = mc->regs;
+	smmu->soc = soc;
+	smmu->dev = dev;
+	smmu->mc = mc;
+
+	smmu->pfn_mask =
+		BIT_MASK(mc->soc->num_address_bits - SMMU_PTE_SHIFT) - 1;
+	dev_dbg(dev, "address bits: %u, PFN mask: %#lx\n",
+		mc->soc->num_address_bits, smmu->pfn_mask);
+	smmu->tlb_mask = (1 << fls(smmu->soc->num_tlb_lines)) - 1;
+	dev_dbg(dev, "TLB lines: %u, mask: %#lx\n", smmu->soc->num_tlb_lines,
+		smmu->tlb_mask);
+
+	value = SMMU_PTC_CONFIG_ENABLE | SMMU_PTC_CONFIG_INDEX_MAP(0x3f);
+
+	if (soc->supports_request_limit)
+		value |= SMMU_PTC_CONFIG_REQ_LIMIT(8);
+
+	smmu_writel(smmu, value, SMMU_PTC_CONFIG);
+
+	value = SMMU_TLB_CONFIG_HIT_UNDER_MISS |
+		SMMU_TLB_CONFIG_ACTIVE_LINES(smmu);
+
+	if (soc->supports_round_robin_arbitration)
+		value |= SMMU_TLB_CONFIG_ROUND_ROBIN_ARBITRATION;
+
+	smmu_writel(smmu, value, SMMU_TLB_CONFIG);
+
+	smmu_flush_ptc_all(smmu);
+	smmu_flush_tlb(smmu);
+	smmu_writel(smmu, SMMU_CONFIG_ENABLE, SMMU_CONFIG);
+	smmu_flush(smmu);
+
+	tegra_smmu_ahb_enable();
+
+	err = iommu_device_sysfs_add(&smmu->iommu, dev, NULL, dev_name(dev));
+	if (err)
+		return ERR_PTR(err);
+
+	err = iommu_device_register(&smmu->iommu, &tegra_smmu_ops, dev);
+	if (err) {
+		iommu_device_sysfs_remove(&smmu->iommu);
+		return ERR_PTR(err);
+	}
+
+	if (IS_ENABLED(CONFIG_DEBUG_FS))
+		tegra_smmu_debugfs_init(smmu);
+
+	return smmu;
+}
+
+void tegra_smmu_remove(struct tegra_smmu *smmu)
+{
+	iommu_device_unregister(&smmu->iommu);
+	iommu_device_sysfs_remove(&smmu->iommu);
+
+	if (IS_ENABLED(CONFIG_DEBUG_FS))
+		tegra_smmu_debugfs_exit(smmu);
+}