iommu/qcom: Add qcom_iommu

An iommu driver for Qualcomm "B" family devices which do implement the
ARM SMMU spec, but not in a way that is compatible with how the arm-smmu
driver is designed.  It seems SMMU_SCR1.GASRAE=1 so the global register
space is not accessible.  This means it needs to get configuration from
devicetree instead of setting it up dynamically.

In the end, other than register definitions, there is not much code to
share with arm-smmu (other than what has already been refactored out
into the pgtable helpers).
Signed-off-by: Rob Clark <robdclark@gmail.com>
Tested-by: Riku Voipio <riku.voipio@linaro.org>
Signed-off-by: Joerg Roedel <jroedel@suse.de>

drivers/iommu/Kconfig

@@ -367,4 +367,14 @@ config MTK_IOMMU_V1
 
 	  if unsure, say N here.
 
+config QCOM_IOMMU
+	# Note: iommu drivers cannot (yet?) be built as modules
+	bool "Qualcomm IOMMU Support"
+	depends on ARCH_QCOM || COMPILE_TEST
+	select IOMMU_API
+	select IOMMU_IO_PGTABLE_LPAE
+	select ARM_DMA_USE_IOMMU
+	help
+	  Support for IOMMU on certain Qualcomm SoCs.
+
 endif # IOMMU_SUPPORT

drivers/iommu/Makefile

@@ -27,3 +27,4 @@ obj-$(CONFIG_TEGRA_IOMMU_SMMU) += tegra-smmu.o
 obj-$(CONFIG_EXYNOS_IOMMU) += exynos-iommu.o
 obj-$(CONFIG_FSL_PAMU) += fsl_pamu.o fsl_pamu_domain.o
 obj-$(CONFIG_S390_IOMMU) += s390-iommu.o
+obj-$(CONFIG_QCOM_IOMMU) += qcom_iommu.o

drivers/iommu/qcom_iommu.c

+/*
+ * IOMMU API for QCOM secure IOMMUs.  Somewhat based on arm-smmu.c
+ *
+ * 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.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ *
+ * Copyright (C) 2013 ARM Limited
+ * Copyright (C) 2017 Red Hat
+ */
+
+#include <linux/atomic.h>
+#include <linux/clk.h>
+#include <linux/delay.h>
+#include <linux/dma-iommu.h>
+#include <linux/dma-mapping.h>
+#include <linux/err.h>
+#include <linux/interrupt.h>
+#include <linux/io.h>
+#include <linux/io-64-nonatomic-hi-lo.h>
+#include <linux/iommu.h>
+#include <linux/iopoll.h>
+#include <linux/kconfig.h>
+#include <linux/module.h>
+#include <linux/mutex.h>
+#include <linux/of.h>
+#include <linux/of_address.h>
+#include <linux/of_device.h>
+#include <linux/of_iommu.h>
+#include <linux/platform_device.h>
+#include <linux/pm.h>
+#include <linux/pm_runtime.h>
+#include <linux/qcom_scm.h>
+#include <linux/slab.h>
+#include <linux/spinlock.h>
+
+#include "io-pgtable.h"
+#include "arm-smmu-regs.h"
+
+#define SMMU_INTR_SEL_NS     0x2000
+
+struct qcom_iommu_ctx;
+
+struct qcom_iommu_dev {
+	/* IOMMU core code handle */
+	struct iommu_device	 iommu;
+	struct device		*dev;
+	struct clk		*iface_clk;
+	struct clk		*bus_clk;
+	void __iomem		*local_base;
+	u32			 sec_id;
+	u8			 num_ctxs;
+	struct qcom_iommu_ctx	*ctxs[0];   /* indexed by asid-1 */
+};
+
+struct qcom_iommu_ctx {
+	struct device		*dev;
+	void __iomem		*base;
+	bool			 secure_init;
+	u8			 asid;      /* asid and ctx bank # are 1:1 */
+};
+
+struct qcom_iommu_domain {
+	struct io_pgtable_ops	*pgtbl_ops;
+	spinlock_t		 pgtbl_lock;
+	struct mutex		 init_mutex; /* Protects iommu pointer */
+	struct iommu_domain	 domain;
+	struct qcom_iommu_dev	*iommu;
+};
+
+static struct qcom_iommu_domain *to_qcom_iommu_domain(struct iommu_domain *dom)
+{
+	return container_of(dom, struct qcom_iommu_domain, domain);
+}
+
+static const struct iommu_ops qcom_iommu_ops;
+
+static struct qcom_iommu_dev * to_iommu(struct iommu_fwspec *fwspec)
+{
+	if (!fwspec || fwspec->ops != &qcom_iommu_ops)
+		return NULL;
+	return fwspec->iommu_priv;
+}
+
+static struct qcom_iommu_ctx * to_ctx(struct iommu_fwspec *fwspec, unsigned asid)
+{
+	struct qcom_iommu_dev *qcom_iommu = to_iommu(fwspec);
+	if (!qcom_iommu)
+		return NULL;
+	return qcom_iommu->ctxs[asid - 1];
+}
+
+static inline void
+iommu_writel(struct qcom_iommu_ctx *ctx, unsigned reg, u32 val)
+{
+	writel_relaxed(val, ctx->base + reg);
+}
+
+static inline void
+iommu_writeq(struct qcom_iommu_ctx *ctx, unsigned reg, u64 val)
+{
+	writeq_relaxed(val, ctx->base + reg);
+}
+
+static inline u32
+iommu_readl(struct qcom_iommu_ctx *ctx, unsigned reg)
+{
+	return readl_relaxed(ctx->base + reg);
+}
+
+static inline u64
+iommu_readq(struct qcom_iommu_ctx *ctx, unsigned reg)
+{
+	return readq_relaxed(ctx->base + reg);
+}
+
+static void qcom_iommu_tlb_sync(void *cookie)
+{
+	struct iommu_fwspec *fwspec = cookie;
+	unsigned i;
+
+	for (i = 0; i < fwspec->num_ids; i++) {
+		struct qcom_iommu_ctx *ctx = to_ctx(fwspec, fwspec->ids[i]);
+		unsigned int val, ret;
+
+		iommu_writel(ctx, ARM_SMMU_CB_TLBSYNC, 0);
+
+		ret = readl_poll_timeout(ctx->base + ARM_SMMU_CB_TLBSTATUS, val,
+					 (val & 0x1) == 0, 0, 5000000);
+		if (ret)
+			dev_err(ctx->dev, "timeout waiting for TLB SYNC\n");
+	}
+}
+
+static void qcom_iommu_tlb_inv_context(void *cookie)
+{
+	struct iommu_fwspec *fwspec = cookie;
+	unsigned i;
+
+	for (i = 0; i < fwspec->num_ids; i++) {
+		struct qcom_iommu_ctx *ctx = to_ctx(fwspec, fwspec->ids[i]);
+		iommu_writel(ctx, ARM_SMMU_CB_S1_TLBIASID, ctx->asid);
+	}
+
+	qcom_iommu_tlb_sync(cookie);
+}
+
+static void qcom_iommu_tlb_inv_range_nosync(unsigned long iova, size_t size,
+					    size_t granule, bool leaf, void *cookie)
+{
+	struct iommu_fwspec *fwspec = cookie;
+	unsigned i, reg;
+
+	reg = leaf ? ARM_SMMU_CB_S1_TLBIVAL : ARM_SMMU_CB_S1_TLBIVA;
+
+	for (i = 0; i < fwspec->num_ids; i++) {
+		struct qcom_iommu_ctx *ctx = to_ctx(fwspec, fwspec->ids[i]);
+		size_t s = size;
+
+		iova &= ~12UL;
+		iova |= ctx->asid;
+		do {
+			iommu_writel(ctx, reg, iova);
+			iova += granule;
+		} while (s -= granule);
+	}
+}
+
+static const struct iommu_gather_ops qcom_gather_ops = {
+	.tlb_flush_all	= qcom_iommu_tlb_inv_context,
+	.tlb_add_flush	= qcom_iommu_tlb_inv_range_nosync,
+	.tlb_sync	= qcom_iommu_tlb_sync,
+};
+
+static irqreturn_t qcom_iommu_fault(int irq, void *dev)
+{
+	struct qcom_iommu_ctx *ctx = dev;
+	u32 fsr, fsynr;
+	u64 iova;
+
+	fsr = iommu_readl(ctx, ARM_SMMU_CB_FSR);
+
+	if (!(fsr & FSR_FAULT))
+		return IRQ_NONE;
+
+	fsynr = iommu_readl(ctx, ARM_SMMU_CB_FSYNR0);
+	iova = iommu_readq(ctx, ARM_SMMU_CB_FAR);
+
+	dev_err_ratelimited(ctx->dev,
+			    "Unhandled context fault: fsr=0x%x, "
+			    "iova=0x%016llx, fsynr=0x%x, cb=%d\n",
+			    fsr, iova, fsynr, ctx->asid);
+
+	iommu_writel(ctx, ARM_SMMU_CB_FSR, fsr);
+
+	return IRQ_HANDLED;
+}
+
+static int qcom_iommu_init_domain(struct iommu_domain *domain,
+				  struct qcom_iommu_dev *qcom_iommu,
+				  struct iommu_fwspec *fwspec)
+{
+	struct qcom_iommu_domain *qcom_domain = to_qcom_iommu_domain(domain);
+	struct io_pgtable_ops *pgtbl_ops;
+	struct io_pgtable_cfg pgtbl_cfg;
+	int i, ret = 0;
+	u32 reg;
+
+	mutex_lock(&qcom_domain->init_mutex);
+	if (qcom_domain->iommu)
+		goto out_unlock;
+
+	pgtbl_cfg = (struct io_pgtable_cfg) {
+		.pgsize_bitmap	= qcom_iommu_ops.pgsize_bitmap,
+		.ias		= 32,
+		.oas		= 40,
+		.tlb		= &qcom_gather_ops,
+		.iommu_dev	= qcom_iommu->dev,
+	};
+
+	qcom_domain->iommu = qcom_iommu;
+	pgtbl_ops = alloc_io_pgtable_ops(ARM_32_LPAE_S1, &pgtbl_cfg, fwspec);
+	if (!pgtbl_ops) {
+		dev_err(qcom_iommu->dev, "failed to allocate pagetable ops\n");
+		ret = -ENOMEM;
+		goto out_clear_iommu;
+	}
+
+	/* Update the domain's page sizes to reflect the page table format */
+	domain->pgsize_bitmap = pgtbl_cfg.pgsize_bitmap;
+	domain->geometry.aperture_end = (1ULL << pgtbl_cfg.ias) - 1;
+	domain->geometry.force_aperture = true;
+
+	for (i = 0; i < fwspec->num_ids; i++) {
+		struct qcom_iommu_ctx *ctx = to_ctx(fwspec, fwspec->ids[i]);
+
+		if (!ctx->secure_init) {
+			ret = qcom_scm_restore_sec_cfg(qcom_iommu->sec_id, ctx->asid);
+			if (ret) {
+				dev_err(qcom_iommu->dev, "secure init failed: %d\n", ret);
+				goto out_clear_iommu;
+			}
+			ctx->secure_init = true;
+		}
+
+		/* TTBRs */
+		iommu_writeq(ctx, ARM_SMMU_CB_TTBR0,
+				pgtbl_cfg.arm_lpae_s1_cfg.ttbr[0] |
+				((u64)ctx->asid << TTBRn_ASID_SHIFT));
+		iommu_writeq(ctx, ARM_SMMU_CB_TTBR1,
+				pgtbl_cfg.arm_lpae_s1_cfg.ttbr[1] |
+				((u64)ctx->asid << TTBRn_ASID_SHIFT));
+
+		/* TTBCR */
+		iommu_writel(ctx, ARM_SMMU_CB_TTBCR2,
+				(pgtbl_cfg.arm_lpae_s1_cfg.tcr >> 32) |
+				TTBCR2_SEP_UPSTREAM);
+		iommu_writel(ctx, ARM_SMMU_CB_TTBCR,
+				pgtbl_cfg.arm_lpae_s1_cfg.tcr);
+
+		/* MAIRs (stage-1 only) */
+		iommu_writel(ctx, ARM_SMMU_CB_S1_MAIR0,
+				pgtbl_cfg.arm_lpae_s1_cfg.mair[0]);
+		iommu_writel(ctx, ARM_SMMU_CB_S1_MAIR1,
+				pgtbl_cfg.arm_lpae_s1_cfg.mair[1]);
+
+		/* SCTLR */
+		reg = SCTLR_CFIE | SCTLR_CFRE | SCTLR_AFE | SCTLR_TRE |
+			SCTLR_M | SCTLR_S1_ASIDPNE;
+
+		if (IS_ENABLED(CONFIG_BIG_ENDIAN))
+			reg |= SCTLR_E;
+
+		iommu_writel(ctx, ARM_SMMU_CB_SCTLR, reg);
+	}
+
+	mutex_unlock(&qcom_domain->init_mutex);
+
+	/* Publish page table ops for map/unmap */
+	qcom_domain->pgtbl_ops = pgtbl_ops;
+
+	return 0;
+
+out_clear_iommu:
+	qcom_domain->iommu = NULL;
+out_unlock:
+	mutex_unlock(&qcom_domain->init_mutex);
+	return ret;
+}
+
+static struct iommu_domain *qcom_iommu_domain_alloc(unsigned type)
+{
+	struct qcom_iommu_domain *qcom_domain;
+
+	if (type != IOMMU_DOMAIN_UNMANAGED && type != IOMMU_DOMAIN_DMA)
+		return NULL;
+	/*
+	 * Allocate the domain and initialise some of its data structures.
+	 * We can't really do anything meaningful until we've added a
+	 * master.
+	 */
+	qcom_domain = kzalloc(sizeof(*qcom_domain), GFP_KERNEL);
+	if (!qcom_domain)
+		return NULL;
+
+	if (type == IOMMU_DOMAIN_DMA &&
+	    iommu_get_dma_cookie(&qcom_domain->domain)) {
+		kfree(qcom_domain);
+		return NULL;
+	}
+
+	mutex_init(&qcom_domain->init_mutex);
+	spin_lock_init(&qcom_domain->pgtbl_lock);
+
+	return &qcom_domain->domain;
+}
+
+static void qcom_iommu_domain_free(struct iommu_domain *domain)
+{
+	struct qcom_iommu_domain *qcom_domain = to_qcom_iommu_domain(domain);
+
+	if (WARN_ON(qcom_domain->iommu))    /* forgot to detach? */
+		return;
+
+	iommu_put_dma_cookie(domain);
+
+	/* NOTE: unmap can be called after client device is powered off,
+	 * for example, with GPUs or anything involving dma-buf.  So we
+	 * cannot rely on the device_link.  Make sure the IOMMU is on to
+	 * avoid unclocked accesses in the TLB inv path:
+	 */
+	pm_runtime_get_sync(qcom_domain->iommu->dev);
+
+	free_io_pgtable_ops(qcom_domain->pgtbl_ops);
+
+	pm_runtime_put_sync(qcom_domain->iommu->dev);
+
+	kfree(qcom_domain);
+}
+
+static int qcom_iommu_attach_dev(struct iommu_domain *domain, struct device *dev)
+{
+	struct qcom_iommu_dev *qcom_iommu = to_iommu(dev->iommu_fwspec);
+	struct qcom_iommu_domain *qcom_domain = to_qcom_iommu_domain(domain);
+	int ret;
+
+	if (!qcom_iommu) {
+		dev_err(dev, "cannot attach to IOMMU, is it on the same bus?\n");
+		return -ENXIO;
+	}
+
+	/* Ensure that the domain is finalized */
+	pm_runtime_get_sync(qcom_iommu->dev);
+	ret = qcom_iommu_init_domain(domain, qcom_iommu, dev->iommu_fwspec);
+	pm_runtime_put_sync(qcom_iommu->dev);
+	if (ret < 0)
+		return ret;
+
+	/*
+	 * Sanity check the domain. We don't support domains across
+	 * different IOMMUs.
+	 */
+	if (qcom_domain->iommu != qcom_iommu) {
+		dev_err(dev, "cannot attach to IOMMU %s while already "
+			"attached to domain on IOMMU %s\n",
+			dev_name(qcom_domain->iommu->dev),
+			dev_name(qcom_iommu->dev));
+		return -EINVAL;
+	}
+
+	return 0;
+}
+
+static void qcom_iommu_detach_dev(struct iommu_domain *domain, struct device *dev)
+{
+	struct iommu_fwspec *fwspec = dev->iommu_fwspec;
+	struct qcom_iommu_dev *qcom_iommu = to_iommu(fwspec);
+	struct qcom_iommu_domain *qcom_domain = to_qcom_iommu_domain(domain);
+	unsigned i;
+
+	if (!qcom_domain->iommu)
+		return;
+
+	pm_runtime_get_sync(qcom_iommu->dev);
+	for (i = 0; i < fwspec->num_ids; i++) {
+		struct qcom_iommu_ctx *ctx = to_ctx(fwspec, fwspec->ids[i]);
+
+		/* Disable the context bank: */
+		iommu_writel(ctx, ARM_SMMU_CB_SCTLR, 0);
+	}
+	pm_runtime_put_sync(qcom_iommu->dev);
+
+	qcom_domain->iommu = NULL;
+}
+
+static int qcom_iommu_map(struct iommu_domain *domain, unsigned long iova,
+			  phys_addr_t paddr, size_t size, int prot)
+{
+	int ret;
+	unsigned long flags;
+	struct qcom_iommu_domain *qcom_domain = to_qcom_iommu_domain(domain);
+	struct io_pgtable_ops *ops = qcom_domain->pgtbl_ops;
+
+	if (!ops)
+		return -ENODEV;
+
+	spin_lock_irqsave(&qcom_domain->pgtbl_lock, flags);
+	ret = ops->map(ops, iova, paddr, size, prot);
+	spin_unlock_irqrestore(&qcom_domain->pgtbl_lock, flags);
+	return ret;
+}
+
+static size_t qcom_iommu_unmap(struct iommu_domain *domain, unsigned long iova,
+			       size_t size)
+{
+	size_t ret;
+	unsigned long flags;
+	struct qcom_iommu_domain *qcom_domain = to_qcom_iommu_domain(domain);
+	struct io_pgtable_ops *ops = qcom_domain->pgtbl_ops;
+
+	if (!ops)
+		return 0;
+
+	/* NOTE: unmap can be called after client device is powered off,
+	 * for example, with GPUs or anything involving dma-buf.  So we
+	 * cannot rely on the device_link.  Make sure the IOMMU is on to
+	 * avoid unclocked accesses in the TLB inv path:
+	 */
+	pm_runtime_get_sync(qcom_domain->iommu->dev);
+	spin_lock_irqsave(&qcom_domain->pgtbl_lock, flags);
+	ret = ops->unmap(ops, iova, size);
+	spin_unlock_irqrestore(&qcom_domain->pgtbl_lock, flags);
+	pm_runtime_put_sync(qcom_domain->iommu->dev);
+
+	return ret;
+}
+
+static phys_addr_t qcom_iommu_iova_to_phys(struct iommu_domain *domain,
+					   dma_addr_t iova)
+{
+	phys_addr_t ret;
+	unsigned long flags;
+	struct qcom_iommu_domain *qcom_domain = to_qcom_iommu_domain(domain);
+	struct io_pgtable_ops *ops = qcom_domain->pgtbl_ops;
+
+	if (!ops)
+		return 0;
+
+	spin_lock_irqsave(&qcom_domain->pgtbl_lock, flags);
+	ret = ops->iova_to_phys(ops, iova);
+	spin_unlock_irqrestore(&qcom_domain->pgtbl_lock, flags);
+
+	return ret;
+}
+
+static bool qcom_iommu_capable(enum iommu_cap cap)
+{
+	switch (cap) {
+	case IOMMU_CAP_CACHE_COHERENCY:
+		/*
+		 * Return true here as the SMMU can always send out coherent
+		 * requests.
+		 */
+		return true;
+	case IOMMU_CAP_NOEXEC:
+		return true;
+	default:
+		return false;
+	}
+}
+
+static int qcom_iommu_add_device(struct device *dev)
+{
+	struct qcom_iommu_dev *qcom_iommu = to_iommu(dev->iommu_fwspec);
+	struct iommu_group *group;
+	struct device_link *link;
+
+	if (!qcom_iommu)
+		return -ENODEV;
+
+	/*
+	 * Establish the link between iommu and master, so that the
+	 * iommu gets runtime enabled/disabled as per the master's
+	 * needs.
+	 */
+	link = device_link_add(dev, qcom_iommu->dev, DL_FLAG_PM_RUNTIME);
+	if (!link) {
+		dev_err(qcom_iommu->dev, "Unable to create device link between %s and %s\n",
+			dev_name(qcom_iommu->dev), dev_name(dev));
+		return -ENODEV;
+	}
+
+	group = iommu_group_get_for_dev(dev);
+	if (IS_ERR_OR_NULL(group))
+		return PTR_ERR_OR_ZERO(group);
+
+	iommu_group_put(group);
+	iommu_device_link(&qcom_iommu->iommu, dev);
+
+	return 0;
+}
+
+static void qcom_iommu_remove_device(struct device *dev)
+{
+	struct qcom_iommu_dev *qcom_iommu = to_iommu(dev->iommu_fwspec);
+
+	if (!qcom_iommu)
+		return;
+
+	iommu_device_unlink(&qcom_iommu->iommu, dev);
+	iommu_group_remove_device(dev);
+	iommu_fwspec_free(dev);
+}
+
+static int qcom_iommu_of_xlate(struct device *dev, struct of_phandle_args *args)
+{
+	struct qcom_iommu_dev *qcom_iommu;
+	struct platform_device *iommu_pdev;
+	unsigned asid = args->args[0];
+
+	if (args->args_count != 1) {
+		dev_err(dev, "incorrect number of iommu params found for %s "
+			"(found %d, expected 1)\n",
+			args->np->full_name, args->args_count);
+		return -EINVAL;
+	}
+
+	iommu_pdev = of_find_device_by_node(args->np);
+	if (WARN_ON(!iommu_pdev))
+		return -EINVAL;
+
+	qcom_iommu = platform_get_drvdata(iommu_pdev);
+
+	/* make sure the asid specified in dt is valid, so we don't have
+	 * to sanity check this elsewhere, since 'asid - 1' is used to
+	 * index into qcom_iommu->ctxs:
+	 */
+	if (WARN_ON(asid < 1) ||
+	    WARN_ON(asid > qcom_iommu->num_ctxs))
+		return -EINVAL;
+
+	if (!dev->iommu_fwspec->iommu_priv) {
+		dev->iommu_fwspec->iommu_priv = qcom_iommu;
+	} else {
+		/* make sure devices iommus dt node isn't referring to
+		 * multiple different iommu devices.  Multiple context
+		 * banks are ok, but multiple devices are not:
+		 */
+		if (WARN_ON(qcom_iommu != dev->iommu_fwspec->iommu_priv))
+			return -EINVAL;
+	}
+
+	return iommu_fwspec_add_ids(dev, &asid, 1);
+}
+
+static const struct iommu_ops qcom_iommu_ops = {
+	.capable	= qcom_iommu_capable,
+	.domain_alloc	= qcom_iommu_domain_alloc,
+	.domain_free	= qcom_iommu_domain_free,
+	.attach_dev	= qcom_iommu_attach_dev,
+	.detach_dev	= qcom_iommu_detach_dev,
+	.map		= qcom_iommu_map,
+	.unmap		= qcom_iommu_unmap,
+	.map_sg		= default_iommu_map_sg,
+	.iova_to_phys	= qcom_iommu_iova_to_phys,
+	.add_device	= qcom_iommu_add_device,
+	.remove_device	= qcom_iommu_remove_device,
+	.device_group	= generic_device_group,
+	.of_xlate	= qcom_iommu_of_xlate,
+	.pgsize_bitmap	= SZ_4K | SZ_64K | SZ_1M | SZ_16M,
+};
+
+static int qcom_iommu_enable_clocks(struct qcom_iommu_dev *qcom_iommu)
+{
+	int ret;
+
+	ret = clk_prepare_enable(qcom_iommu->iface_clk);
+	if (ret) {
+		dev_err(qcom_iommu->dev, "Couldn't enable iface_clk\n");
+		return ret;
+	}
+
+	ret = clk_prepare_enable(qcom_iommu->bus_clk);
+	if (ret) {
+		dev_err(qcom_iommu->dev, "Couldn't enable bus_clk\n");
+		clk_disable_unprepare(qcom_iommu->iface_clk);
+		return ret;
+	}
+
+	return 0;
+}
+
+static void qcom_iommu_disable_clocks(struct qcom_iommu_dev *qcom_iommu)
+{
+	clk_disable_unprepare(qcom_iommu->bus_clk);
+	clk_disable_unprepare(qcom_iommu->iface_clk);
+}
+
+static int get_asid(const struct device_node *np)
+{
+	u32 reg;
+
+	/* read the "reg" property directly to get the relative address
+	 * of the context bank, and calculate the asid from that:
+	 */
+	if (of_property_read_u32_index(np, "reg", 0, &reg))
+		return -ENODEV;
+
+	return reg / 0x1000;      /* context banks are 0x1000 apart */
+}
+
+static int qcom_iommu_ctx_probe(struct platform_device *pdev)
+{
+	struct qcom_iommu_ctx *ctx;
+	struct device *dev = &pdev->dev;
+	struct qcom_iommu_dev *qcom_iommu = dev_get_drvdata(dev->parent);
+	struct resource *res;
+	int ret, irq;
+
+	ctx = devm_kzalloc(dev, sizeof(*ctx), GFP_KERNEL);
+	if (!ctx)
+		return -ENOMEM;
+
+	ctx->dev = dev;
+	platform_set_drvdata(pdev, ctx);
+
+	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+	ctx->base = devm_ioremap_resource(dev, res);
+	if (IS_ERR(ctx->base))
+		return PTR_ERR(ctx->base);
+
+	irq = platform_get_irq(pdev, 0);
+	if (irq < 0) {
+		dev_err(dev, "failed to get irq\n");
+		return -ENODEV;
+	}
+
+	/* clear IRQs before registering fault handler, just in case the
+	 * boot-loader left us a surprise:
+	 */
+	iommu_writel(ctx, ARM_SMMU_CB_FSR, iommu_readl(ctx, ARM_SMMU_CB_FSR));
+
+	ret = devm_request_irq(dev, irq,
+			       qcom_iommu_fault,
+			       IRQF_SHARED,
+			       "qcom-iommu-fault",
+			       ctx);
+	if (ret) {
+		dev_err(dev, "failed to request IRQ %u\n", irq);
+		return ret;
+	}
+
+	ret = get_asid(dev->of_node);
+	if (ret < 0) {
+		dev_err(dev, "missing reg property\n");
+		return ret;
+	}
+
+	ctx->asid = ret;
+
+	dev_dbg(dev, "found asid %u\n", ctx->asid);
+
+	qcom_iommu->ctxs[ctx->asid - 1] = ctx;
+
+	return 0;
+}
+
+static int qcom_iommu_ctx_remove(struct platform_device *pdev)
+{
+	struct qcom_iommu_dev *qcom_iommu = dev_get_drvdata(pdev->dev.parent);
+	struct qcom_iommu_ctx *ctx = platform_get_drvdata(pdev);
+
+	platform_set_drvdata(pdev, NULL);
+
+	qcom_iommu->ctxs[ctx->asid - 1] = NULL;
+
+	return 0;
+}
+
+static const struct of_device_id ctx_of_match[] = {
+	{ .compatible = "qcom,msm-iommu-v1-ns" },
+	{ .compatible = "qcom,msm-iommu-v1-sec" },
+	{ /* sentinel */ }
+};
+
+static struct platform_driver qcom_iommu_ctx_driver = {
+	.driver	= {
+		.name		= "qcom-iommu-ctx",
+		.of_match_table	= of_match_ptr(ctx_of_match),
+	},
+	.probe	= qcom_iommu_ctx_probe,
+	.remove = qcom_iommu_ctx_remove,
+};
+
+static int qcom_iommu_device_probe(struct platform_device *pdev)
+{
+	struct device_node *child;
+	struct qcom_iommu_dev *qcom_iommu;
+	struct device *dev = &pdev->dev;
+	struct resource *res;
+	int ret, sz, max_asid = 0;
+
+	/* find the max asid (which is 1:1 to ctx bank idx), so we know how
+	 * many child ctx devices we have:
+	 */
+	for_each_child_of_node(dev->of_node, child)
+		max_asid = max(max_asid, get_asid(child));
+
+	sz = sizeof(*qcom_iommu) + (max_asid * sizeof(qcom_iommu->ctxs[0]));
+
+	qcom_iommu = devm_kzalloc(dev, sz, GFP_KERNEL);
+	if (!qcom_iommu)
+		return -ENOMEM;
+	qcom_iommu->num_ctxs = max_asid;
+	qcom_iommu->dev = dev;
+
+	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+	if (res)
+		qcom_iommu->local_base = devm_ioremap_resource(dev, res);
+
+	qcom_iommu->iface_clk = devm_clk_get(dev, "iface");
+	if (IS_ERR(qcom_iommu->iface_clk)) {
+		dev_err(dev, "failed to get iface clock\n");
+		return PTR_ERR(qcom_iommu->iface_clk);
+	}
+
+	qcom_iommu->bus_clk = devm_clk_get(dev, "bus");
+	if (IS_ERR(qcom_iommu->bus_clk)) {
+		dev_err(dev, "failed to get bus clock\n");
+		return PTR_ERR(qcom_iommu->bus_clk);
+	}
+
+	if (of_property_read_u32(dev->of_node, "qcom,iommu-secure-id",
+				 &qcom_iommu->sec_id)) {
+		dev_err(dev, "missing qcom,iommu-secure-id property\n");
+		return -ENODEV;
+	}
+
+	platform_set_drvdata(pdev, qcom_iommu);
+
+	pm_runtime_enable(dev);
+
+	/* register context bank devices, which are child nodes: */
+	ret = devm_of_platform_populate(dev);
+	if (ret) {
+		dev_err(dev, "Failed to populate iommu contexts\n");
+		return ret;
+	}
+
+	ret = iommu_device_sysfs_add(&qcom_iommu->iommu, dev, NULL,
+				     dev_name(dev));
+	if (ret) {
+		dev_err(dev, "Failed to register iommu in sysfs\n");
+		return ret;
+	}
+
+	iommu_device_set_ops(&qcom_iommu->iommu, &qcom_iommu_ops);
+	iommu_device_set_fwnode(&qcom_iommu->iommu, dev->fwnode);
+
+	ret = iommu_device_register(&qcom_iommu->iommu);
+	if (ret) {
+		dev_err(dev, "Failed to register iommu\n");
+		return ret;
+	}
+
+	bus_set_iommu(&platform_bus_type, &qcom_iommu_ops);
+
+	if (qcom_iommu->local_base) {
+		pm_runtime_get_sync(dev);
+		writel_relaxed(0xffffffff, qcom_iommu->local_base + SMMU_INTR_SEL_NS);
+		pm_runtime_put_sync(dev);
+	}
+
+	return 0;
+}
+
+static int qcom_iommu_device_remove(struct platform_device *pdev)
+{
+	struct qcom_iommu_dev *qcom_iommu = platform_get_drvdata(pdev);
+
+	bus_set_iommu(&platform_bus_type, NULL);
+
+	pm_runtime_force_suspend(&pdev->dev);
+	platform_set_drvdata(pdev, NULL);
+	iommu_device_sysfs_remove(&qcom_iommu->iommu);
+	iommu_device_unregister(&qcom_iommu->iommu);
+
+	return 0;
+}
+
+#ifdef CONFIG_PM
+static int qcom_iommu_resume(struct device *dev)
+{
+	struct platform_device *pdev = to_platform_device(dev);
+	struct qcom_iommu_dev *qcom_iommu = platform_get_drvdata(pdev);
+
+	return qcom_iommu_enable_clocks(qcom_iommu);
+}
+
+static int qcom_iommu_suspend(struct device *dev)
+{
+	struct platform_device *pdev = to_platform_device(dev);
+	struct qcom_iommu_dev *qcom_iommu = platform_get_drvdata(pdev);
+
+	qcom_iommu_disable_clocks(qcom_iommu);
+
+	return 0;
+}
+#endif
+
+static const struct dev_pm_ops qcom_iommu_pm_ops = {
+	SET_RUNTIME_PM_OPS(qcom_iommu_suspend, qcom_iommu_resume, NULL)
+	SET_SYSTEM_SLEEP_PM_OPS(pm_runtime_force_suspend,
+				pm_runtime_force_resume)
+};
+
+static const struct of_device_id qcom_iommu_of_match[] = {
+	{ .compatible = "qcom,msm-iommu-v1" },
+	{ /* sentinel */ }
+};
+MODULE_DEVICE_TABLE(of, qcom_iommu_of_match);
+
+static struct platform_driver qcom_iommu_driver = {
+	.driver	= {
+		.name		= "qcom-iommu",
+		.of_match_table	= of_match_ptr(qcom_iommu_of_match),
+		.pm		= &qcom_iommu_pm_ops,
+	},
+	.probe	= qcom_iommu_device_probe,
+	.remove	= qcom_iommu_device_remove,
+};
+
+static int __init qcom_iommu_init(void)
+{
+	int ret;
+
+	ret = platform_driver_register(&qcom_iommu_ctx_driver);
+	if (ret)
+		return ret;
+
+	ret = platform_driver_register(&qcom_iommu_driver);
+	if (ret)
+		platform_driver_unregister(&qcom_iommu_ctx_driver);
+
+	return ret;
+}
+
+static void __exit qcom_iommu_exit(void)
+{
+	platform_driver_unregister(&qcom_iommu_driver);
+	platform_driver_unregister(&qcom_iommu_ctx_driver);
+}
+
+module_init(qcom_iommu_init);
+module_exit(qcom_iommu_exit);
+
+IOMMU_OF_DECLARE(qcom_iommu_dev, "qcom,msm-iommu-v1", NULL);
+
+MODULE_DESCRIPTION("IOMMU API for QCOM IOMMU v1 implementations");
+MODULE_LICENSE("GPL v2");