iommu/rockchip: rk3288 iommu driver

The rk3288 has several iommus.  Each iommu belongs to a single master
device.  There is one device (ISP) that has two slave iommus, but that
case is not yet supported by this driver.

At subsys init, the iommu driver registers itself as the iommu driver for
the platform bus.  The master devices find their slave iommus using the
"iommus" field in their devicetree description.  Since each slave iommu
belongs to exactly one master, their is no additional data needed at probe
to associate a slave with its master.

An iommu device's power domain, clock and irq are all shared with its
master device, and the master device must be careful to attach from the
iommu only after powering and clocking it (and leave it powered and
clocked before detaching).  Because their is no guarantee what the status
of the iommu is at probe, and since the driver does not even know if the
device is powered, we delay requesting its irq until the master device
attaches, at which point we have a guarantee that the device is powered
and clocked and we can reset it and disable its interrupt mask.

An iommu_domain describes a virtual iova address space.  Each iommu_domain
has a corresponding page table that lists the mappings from iova to
physical address.

For the rk3288 iommu, the page table has two levels:
 The Level 1 "directory_table" has 1024 4-byte dte entries.
 Each dte points to a level 2 "page_table".
 Each level 2 page_table has 1024 4-byte pte entries.
 Each pte points to a 4 KiB page of memory.

An iommu_domain is created when a dma_iommu_mapping is created via
arm_iommu_create_mapping.  Master devices can then attach themselves to
this mapping (or attach the mapping to themselves?) by calling
arm_iommu_attach_device().  This in turn instructs the iommu driver to
write the page table's physical address into the slave iommu's "Directory
Table Entry" (DTE) register.

In fact multiple master devices, each with their own slave iommu device,
can all attach to the same mapping.  The iommus for these devices will
share the same iommu_domain and therefore point to the same page table.
Thus, the iommu domain maintains a list of iommu devices which are
attached.  This driver relies on the iommu core to ensure that all devices
have detached before destroying a domain.

v6: - add .add/remove_device() callbacks.
    - parse platform_device device tree nodes for "iommus" property
    - store platform device pointer as group iommudata
    - Check for existence of iommu group instead of relying on a
      dev_get_drvdata() to return NULL for a NULL device.

v7: - fixup some strings.
    - In rk_iommu_disable_paging() # and % were reversed.

Signed-off-by: Daniel Kurtz <djkurtz@chromium.org>
Signed-off-by: Simon Xue <xxm@rock-chips.com>
Reviewed-by: Grant Grundler <grundler@chromium.org>
Reviewed-by: Stéphane Marchesin <marcheu@chromium.org>
Tested-by: Heiko Stuebner <heiko@sntech.de>
Signed-off-by: Joerg Roedel <jroedel@suse.de>

3 files changed, 1051 insertions, 0 deletions

diff --git a/drivers/iommu/Kconfig b/drivers/iommu/Kconfig
index dd5112265cc9..d0a1261eb1ba 100644
--- a/drivers/iommu/Kconfig
+++ b/drivers/iommu/Kconfig
@@ -152,6 +152,18 @@ config OMAP_IOMMU_DEBUG
 
          Say N unless you know you need this.
 
+config ROCKCHIP_IOMMU
+	bool "Rockchip IOMMU Support"
+	depends on ARCH_ROCKCHIP
+	select IOMMU_API
+	select ARM_DMA_USE_IOMMU
+	help
+	  Support for IOMMUs found on Rockchip rk32xx SOCs.
+	  These IOMMUs allow virtualization of the address space used by most
+	  cores within the multimedia subsystem.
+	  Say Y here if you are using a Rockchip SoC that includes an IOMMU
+	  device.
+
 config TEGRA_IOMMU_GART
 	bool "Tegra GART IOMMU Support"
 	depends on ARCH_TEGRA_2x_SOC
diff --git a/drivers/iommu/Makefile b/drivers/iommu/Makefile
index 16edef74b8ee..3e47ef35a35f 100644
--- a/drivers/iommu/Makefile
+++ b/drivers/iommu/Makefile
@@ -13,6 +13,7 @@ obj-$(CONFIG_IRQ_REMAP) += intel_irq_remapping.o irq_remapping.o
 obj-$(CONFIG_OMAP_IOMMU) += omap-iommu.o
 obj-$(CONFIG_OMAP_IOMMU) += omap-iommu2.o
 obj-$(CONFIG_OMAP_IOMMU_DEBUG) += omap-iommu-debug.o
+obj-$(CONFIG_ROCKCHIP_IOMMU) += rockchip-iommu.o
 obj-$(CONFIG_TEGRA_IOMMU_GART) += tegra-gart.o
 obj-$(CONFIG_TEGRA_IOMMU_SMMU) += tegra-smmu.o
 obj-$(CONFIG_EXYNOS_IOMMU) += exynos-iommu.o
diff --git a/drivers/iommu/rockchip-iommu.c b/drivers/iommu/rockchip-iommu.c
new file mode 100644
index 000000000000..b2023af384b9
--- /dev/null
+++ b/drivers/iommu/rockchip-iommu.c
@@ -0,0 +1,1038 @@
+/*
+ * 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 <asm/cacheflush.h>
+#include <asm/pgtable.h>
+#include <linux/compiler.h>
+#include <linux/delay.h>
+#include <linux/device.h>
+#include <linux/errno.h>
+#include <linux/interrupt.h>
+#include <linux/io.h>
+#include <linux/iommu.h>
+#include <linux/jiffies.h>
+#include <linux/list.h>
+#include <linux/mm.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/of_platform.h>
+#include <linux/platform_device.h>
+#include <linux/slab.h>
+#include <linux/spinlock.h>
+
+/** MMU register offsets */
+#define RK_MMU_DTE_ADDR		0x00	/* Directory table address */
+#define RK_MMU_STATUS		0x04
+#define RK_MMU_COMMAND		0x08
+#define RK_MMU_PAGE_FAULT_ADDR	0x0C	/* IOVA of last page fault */
+#define RK_MMU_ZAP_ONE_LINE	0x10	/* Shootdown one IOTLB entry */
+#define RK_MMU_INT_RAWSTAT	0x14	/* IRQ status ignoring mask */
+#define RK_MMU_INT_CLEAR	0x18	/* Acknowledge and re-arm irq */
+#define RK_MMU_INT_MASK		0x1C	/* IRQ enable */
+#define RK_MMU_INT_STATUS	0x20	/* IRQ status after masking */
+#define RK_MMU_AUTO_GATING	0x24
+
+#define DTE_ADDR_DUMMY		0xCAFEBABE
+#define FORCE_RESET_TIMEOUT	100	/* ms */
+
+/* RK_MMU_STATUS fields */
+#define RK_MMU_STATUS_PAGING_ENABLED       BIT(0)
+#define RK_MMU_STATUS_PAGE_FAULT_ACTIVE    BIT(1)
+#define RK_MMU_STATUS_STALL_ACTIVE         BIT(2)
+#define RK_MMU_STATUS_IDLE                 BIT(3)
+#define RK_MMU_STATUS_REPLAY_BUFFER_EMPTY  BIT(4)
+#define RK_MMU_STATUS_PAGE_FAULT_IS_WRITE  BIT(5)
+#define RK_MMU_STATUS_STALL_NOT_ACTIVE     BIT(31)
+
+/* RK_MMU_COMMAND command values */
+#define RK_MMU_CMD_ENABLE_PAGING    0  /* Enable memory translation */
+#define RK_MMU_CMD_DISABLE_PAGING   1  /* Disable memory translation */
+#define RK_MMU_CMD_ENABLE_STALL     2  /* Stall paging to allow other cmds */
+#define RK_MMU_CMD_DISABLE_STALL    3  /* Stop stall re-enables paging */
+#define RK_MMU_CMD_ZAP_CACHE        4  /* Shoot down entire IOTLB */
+#define RK_MMU_CMD_PAGE_FAULT_DONE  5  /* Clear page fault */
+#define RK_MMU_CMD_FORCE_RESET      6  /* Reset all registers */
+
+/* RK_MMU_INT_* register fields */
+#define RK_MMU_IRQ_PAGE_FAULT    0x01  /* page fault */
+#define RK_MMU_IRQ_BUS_ERROR     0x02  /* bus read error */
+#define RK_MMU_IRQ_MASK          (RK_MMU_IRQ_PAGE_FAULT | RK_MMU_IRQ_BUS_ERROR)
+
+#define NUM_DT_ENTRIES 1024
+#define NUM_PT_ENTRIES 1024
+
+#define SPAGE_ORDER 12
+#define SPAGE_SIZE (1 << SPAGE_ORDER)
+
+ /*
+  * Support mapping any size that fits in one page table:
+  *   4 KiB to 4 MiB
+  */
+#define RK_IOMMU_PGSIZE_BITMAP 0x007ff000
+
+#define IOMMU_REG_POLL_COUNT_FAST 1000
+
+struct rk_iommu_domain {
+	struct list_head iommus;
+	u32 *dt; /* page directory table */
+	spinlock_t iommus_lock; /* lock for iommus list */
+	spinlock_t dt_lock; /* lock for modifying page directory table */
+};
+
+struct rk_iommu {
+	struct device *dev;
+	void __iomem *base;
+	int irq;
+	struct list_head node; /* entry in rk_iommu_domain.iommus */
+	struct iommu_domain *domain; /* domain to which iommu is attached */
+};
+
+static inline void rk_table_flush(u32 *va, unsigned int count)
+{
+	phys_addr_t pa_start = virt_to_phys(va);
+	phys_addr_t pa_end = virt_to_phys(va + count);
+	size_t size = pa_end - pa_start;
+
+	__cpuc_flush_dcache_area(va, size);
+	outer_flush_range(pa_start, pa_end);
+}
+
+/**
+ * Inspired by _wait_for in intel_drv.h
+ * This is NOT safe for use in interrupt context.
+ *
+ * Note that it's important that we check the condition again after having
+ * timed out, since the timeout could be due to preemption or similar and
+ * we've never had a chance to check the condition before the timeout.
+ */
+#define rk_wait_for(COND, MS) ({ \
+	unsigned long timeout__ = jiffies + msecs_to_jiffies(MS) + 1;	\
+	int ret__ = 0;							\
+	while (!(COND)) {						\
+		if (time_after(jiffies, timeout__)) {			\
+			ret__ = (COND) ? 0 : -ETIMEDOUT;		\
+			break;						\
+		}							\
+		usleep_range(50, 100);					\
+	}								\
+	ret__;								\
+})
+
+/*
+ * The Rockchip rk3288 iommu uses a 2-level page table.
+ * The first level is the "Directory Table" (DT).
+ * The DT consists of 1024 4-byte Directory Table Entries (DTEs), each pointing
+ * to a "Page Table".
+ * The second level is the 1024 Page Tables (PT).
+ * Each PT consists of 1024 4-byte Page Table Entries (PTEs), each pointing to
+ * a 4 KB page of physical memory.
+ *
+ * The DT and each PT fits in a single 4 KB page (4-bytes * 1024 entries).
+ * Each iommu device has a MMU_DTE_ADDR register that contains the physical
+ * address of the start of the DT page.
+ *
+ * The structure of the page table is as follows:
+ *
+ *                   DT
+ * MMU_DTE_ADDR -> +-----+
+ *                 |     |
+ *                 +-----+     PT
+ *                 | DTE | -> +-----+
+ *                 +-----+    |     |     Memory
+ *                 |     |    +-----+     Page
+ *                 |     |    | PTE | -> +-----+
+ *                 +-----+    +-----+    |     |
+ *                            |     |    |     |
+ *                            |     |    |     |
+ *                            +-----+    |     |
+ *                                       |     |
+ *                                       |     |
+ *                                       +-----+
+ */
+
+/*
+ * Each DTE has a PT address and a valid bit:
+ * +---------------------+-----------+-+
+ * | PT address          | Reserved  |V|
+ * +---------------------+-----------+-+
+ *  31:12 - PT address (PTs always starts on a 4 KB boundary)
+ *  11: 1 - Reserved
+ *      0 - 1 if PT @ PT address is valid
+ */
+#define RK_DTE_PT_ADDRESS_MASK    0xfffff000
+#define RK_DTE_PT_VALID           BIT(0)
+
+static inline phys_addr_t rk_dte_pt_address(u32 dte)
+{
+	return (phys_addr_t)dte & RK_DTE_PT_ADDRESS_MASK;
+}
+
+static inline bool rk_dte_is_pt_valid(u32 dte)
+{
+	return dte & RK_DTE_PT_VALID;
+}
+
+static u32 rk_mk_dte(u32 *pt)
+{
+	phys_addr_t pt_phys = virt_to_phys(pt);
+	return (pt_phys & RK_DTE_PT_ADDRESS_MASK) | RK_DTE_PT_VALID;
+}
+
+/*
+ * Each PTE has a Page address, some flags and a valid bit:
+ * +---------------------+---+-------+-+
+ * | Page address        |Rsv| Flags |V|
+ * +---------------------+---+-------+-+
+ *  31:12 - Page address (Pages always start on a 4 KB boundary)
+ *  11: 9 - Reserved
+ *   8: 1 - Flags
+ *      8 - Read allocate - allocate cache space on read misses
+ *      7 - Read cache - enable cache & prefetch of data
+ *      6 - Write buffer - enable delaying writes on their way to memory
+ *      5 - Write allocate - allocate cache space on write misses
+ *      4 - Write cache - different writes can be merged together
+ *      3 - Override cache attributes
+ *          if 1, bits 4-8 control cache attributes
+ *          if 0, the system bus defaults are used
+ *      2 - Writable
+ *      1 - Readable
+ *      0 - 1 if Page @ Page address is valid
+ */
+#define RK_PTE_PAGE_ADDRESS_MASK  0xfffff000
+#define RK_PTE_PAGE_FLAGS_MASK    0x000001fe
+#define RK_PTE_PAGE_WRITABLE      BIT(2)
+#define RK_PTE_PAGE_READABLE      BIT(1)
+#define RK_PTE_PAGE_VALID         BIT(0)
+
+static inline phys_addr_t rk_pte_page_address(u32 pte)
+{
+	return (phys_addr_t)pte & RK_PTE_PAGE_ADDRESS_MASK;
+}
+
+static inline bool rk_pte_is_page_valid(u32 pte)
+{
+	return pte & RK_PTE_PAGE_VALID;
+}
+
+/* TODO: set cache flags per prot IOMMU_CACHE */
+static u32 rk_mk_pte(phys_addr_t page, int prot)
+{
+	u32 flags = 0;
+	flags |= (prot & IOMMU_READ) ? RK_PTE_PAGE_READABLE : 0;
+	flags |= (prot & IOMMU_WRITE) ? RK_PTE_PAGE_WRITABLE : 0;
+	page &= RK_PTE_PAGE_ADDRESS_MASK;
+	return page | flags | RK_PTE_PAGE_VALID;
+}
+
+static u32 rk_mk_pte_invalid(u32 pte)
+{
+	return pte & ~RK_PTE_PAGE_VALID;
+}
+
+/*
+ * rk3288 iova (IOMMU Virtual Address) format
+ *  31       22.21       12.11          0
+ * +-----------+-----------+-------------+
+ * | DTE index | PTE index | Page offset |
+ * +-----------+-----------+-------------+
+ *  31:22 - DTE index   - index of DTE in DT
+ *  21:12 - PTE index   - index of PTE in PT @ DTE.pt_address
+ *  11: 0 - Page offset - offset into page @ PTE.page_address
+ */
+#define RK_IOVA_DTE_MASK    0xffc00000
+#define RK_IOVA_DTE_SHIFT   22
+#define RK_IOVA_PTE_MASK    0x003ff000
+#define RK_IOVA_PTE_SHIFT   12
+#define RK_IOVA_PAGE_MASK   0x00000fff
+#define RK_IOVA_PAGE_SHIFT  0
+
+static u32 rk_iova_dte_index(dma_addr_t iova)
+{
+	return (u32)(iova & RK_IOVA_DTE_MASK) >> RK_IOVA_DTE_SHIFT;
+}
+
+static u32 rk_iova_pte_index(dma_addr_t iova)
+{
+	return (u32)(iova & RK_IOVA_PTE_MASK) >> RK_IOVA_PTE_SHIFT;
+}
+
+static u32 rk_iova_page_offset(dma_addr_t iova)
+{
+	return (u32)(iova & RK_IOVA_PAGE_MASK) >> RK_IOVA_PAGE_SHIFT;
+}
+
+static u32 rk_iommu_read(struct rk_iommu *iommu, u32 offset)
+{
+	return readl(iommu->base + offset);
+}
+
+static void rk_iommu_write(struct rk_iommu *iommu, u32 offset, u32 value)
+{
+	writel(value, iommu->base + offset);
+}
+
+static void rk_iommu_command(struct rk_iommu *iommu, u32 command)
+{
+	writel(command, iommu->base + RK_MMU_COMMAND);
+}
+
+static void rk_iommu_zap_lines(struct rk_iommu *iommu, dma_addr_t iova,
+			       size_t size)
+{
+	dma_addr_t iova_end = iova + size;
+	/*
+	 * TODO(djkurtz): Figure out when it is more efficient to shootdown the
+	 * entire iotlb rather than iterate over individual iovas.
+	 */
+	for (; iova < iova_end; iova += SPAGE_SIZE)
+		rk_iommu_write(iommu, RK_MMU_ZAP_ONE_LINE, iova);
+}
+
+static bool rk_iommu_is_stall_active(struct rk_iommu *iommu)
+{
+	return rk_iommu_read(iommu, RK_MMU_STATUS) & RK_MMU_STATUS_STALL_ACTIVE;
+}
+
+static bool rk_iommu_is_paging_enabled(struct rk_iommu *iommu)
+{
+	return rk_iommu_read(iommu, RK_MMU_STATUS) &
+			     RK_MMU_STATUS_PAGING_ENABLED;
+}
+
+static int rk_iommu_enable_stall(struct rk_iommu *iommu)
+{
+	int ret;
+
+	if (rk_iommu_is_stall_active(iommu))
+		return 0;
+
+	/* Stall can only be enabled if paging is enabled */
+	if (!rk_iommu_is_paging_enabled(iommu))
+		return 0;
+
+	rk_iommu_command(iommu, RK_MMU_CMD_ENABLE_STALL);
+
+	ret = rk_wait_for(rk_iommu_is_stall_active(iommu), 1);
+	if (ret)
+		dev_err(iommu->dev, "Enable stall request timed out, status: %#08x\n",
+			rk_iommu_read(iommu, RK_MMU_STATUS));
+
+	return ret;
+}
+
+static int rk_iommu_disable_stall(struct rk_iommu *iommu)
+{
+	int ret;
+
+	if (!rk_iommu_is_stall_active(iommu))
+		return 0;
+
+	rk_iommu_command(iommu, RK_MMU_CMD_DISABLE_STALL);
+
+	ret = rk_wait_for(!rk_iommu_is_stall_active(iommu), 1);
+	if (ret)
+		dev_err(iommu->dev, "Disable stall request timed out, status: %#08x\n",
+			rk_iommu_read(iommu, RK_MMU_STATUS));
+
+	return ret;
+}
+
+static int rk_iommu_enable_paging(struct rk_iommu *iommu)
+{
+	int ret;
+
+	if (rk_iommu_is_paging_enabled(iommu))
+		return 0;
+
+	rk_iommu_command(iommu, RK_MMU_CMD_ENABLE_PAGING);
+
+	ret = rk_wait_for(rk_iommu_is_paging_enabled(iommu), 1);
+	if (ret)
+		dev_err(iommu->dev, "Enable paging request timed out, status: %#08x\n",
+			rk_iommu_read(iommu, RK_MMU_STATUS));
+
+	return ret;
+}
+
+static int rk_iommu_disable_paging(struct rk_iommu *iommu)
+{
+	int ret;
+
+	if (!rk_iommu_is_paging_enabled(iommu))
+		return 0;
+
+	rk_iommu_command(iommu, RK_MMU_CMD_DISABLE_PAGING);
+
+	ret = rk_wait_for(!rk_iommu_is_paging_enabled(iommu), 1);
+	if (ret)
+		dev_err(iommu->dev, "Disable paging request timed out, status: %#08x\n",
+			rk_iommu_read(iommu, RK_MMU_STATUS));
+
+	return ret;
+}
+
+static int rk_iommu_force_reset(struct rk_iommu *iommu)
+{
+	int ret;
+	u32 dte_addr;
+
+	/*
+	 * Check if register DTE_ADDR is working by writing DTE_ADDR_DUMMY
+	 * and verifying that upper 5 nybbles are read back.
+	 */
+	rk_iommu_write(iommu, RK_MMU_DTE_ADDR, DTE_ADDR_DUMMY);
+
+	dte_addr = rk_iommu_read(iommu, RK_MMU_DTE_ADDR);
+	if (dte_addr != (DTE_ADDR_DUMMY & RK_DTE_PT_ADDRESS_MASK)) {
+		dev_err(iommu->dev, "Error during raw reset. MMU_DTE_ADDR is not functioning\n");
+		return -EFAULT;
+	}
+
+	rk_iommu_command(iommu, RK_MMU_CMD_FORCE_RESET);
+
+	ret = rk_wait_for(rk_iommu_read(iommu, RK_MMU_DTE_ADDR) == 0x00000000,
+			  FORCE_RESET_TIMEOUT);
+	if (ret)
+		dev_err(iommu->dev, "FORCE_RESET command timed out\n");
+
+	return ret;
+}
+
+static void log_iova(struct rk_iommu *iommu, dma_addr_t iova)
+{
+	u32 dte_index, pte_index, page_offset;
+	u32 mmu_dte_addr;
+	phys_addr_t mmu_dte_addr_phys, dte_addr_phys;
+	u32 *dte_addr;
+	u32 dte;
+	phys_addr_t pte_addr_phys = 0;
+	u32 *pte_addr = NULL;
+	u32 pte = 0;
+	phys_addr_t page_addr_phys = 0;
+	u32 page_flags = 0;
+
+	dte_index = rk_iova_dte_index(iova);
+	pte_index = rk_iova_pte_index(iova);
+	page_offset = rk_iova_page_offset(iova);
+
+	mmu_dte_addr = rk_iommu_read(iommu, RK_MMU_DTE_ADDR);
+	mmu_dte_addr_phys = (phys_addr_t)mmu_dte_addr;
+
+	dte_addr_phys = mmu_dte_addr_phys + (4 * dte_index);
+	dte_addr = phys_to_virt(dte_addr_phys);
+	dte = *dte_addr;
+
+	if (!rk_dte_is_pt_valid(dte))
+		goto print_it;
+
+	pte_addr_phys = rk_dte_pt_address(dte) + (pte_index * 4);
+	pte_addr = phys_to_virt(pte_addr_phys);
+	pte = *pte_addr;
+
+	if (!rk_pte_is_page_valid(pte))
+		goto print_it;
+
+	page_addr_phys = rk_pte_page_address(pte) + page_offset;
+	page_flags = pte & RK_PTE_PAGE_FLAGS_MASK;
+
+print_it:
+	dev_err(iommu->dev, "iova = %pad: dte_index: %#03x pte_index: %#03x page_offset: %#03x\n",
+		&iova, dte_index, pte_index, page_offset);
+	dev_err(iommu->dev, "mmu_dte_addr: %pa dte@%pa: %#08x valid: %u pte@%pa: %#08x valid: %u page@%pa flags: %#03x\n",
+		&mmu_dte_addr_phys, &dte_addr_phys, dte,
+		rk_dte_is_pt_valid(dte), &pte_addr_phys, pte,
+		rk_pte_is_page_valid(pte), &page_addr_phys, page_flags);
+}
+
+static irqreturn_t rk_iommu_irq(int irq, void *dev_id)
+{
+	struct rk_iommu *iommu = dev_id;
+	u32 status;
+	u32 int_status;
+	dma_addr_t iova;
+
+	int_status = rk_iommu_read(iommu, RK_MMU_INT_STATUS);
+	if (int_status == 0)
+		return IRQ_NONE;
+
+	iova = rk_iommu_read(iommu, RK_MMU_PAGE_FAULT_ADDR);
+
+	if (int_status & RK_MMU_IRQ_PAGE_FAULT) {
+		int flags;
+
+		status = rk_iommu_read(iommu, RK_MMU_STATUS);
+		flags = (status & RK_MMU_STATUS_PAGE_FAULT_IS_WRITE) ?
+				IOMMU_FAULT_WRITE : IOMMU_FAULT_READ;
+
+		dev_err(iommu->dev, "Page fault at %pad of type %s\n",
+			&iova,
+			(flags == IOMMU_FAULT_WRITE) ? "write" : "read");
+
+		log_iova(iommu, iova);
+
+		/*
+		 * Report page fault to any installed handlers.
+		 * Ignore the return code, though, since we always zap cache
+		 * and clear the page fault anyway.
+		 */
+		if (iommu->domain)
+			report_iommu_fault(iommu->domain, iommu->dev, iova,
+					   flags);
+		else
+			dev_err(iommu->dev, "Page fault while iommu not attached to domain?\n");
+
+		rk_iommu_command(iommu, RK_MMU_CMD_ZAP_CACHE);
+		rk_iommu_command(iommu, RK_MMU_CMD_PAGE_FAULT_DONE);
+	}
+
+	if (int_status & RK_MMU_IRQ_BUS_ERROR)
+		dev_err(iommu->dev, "BUS_ERROR occurred at %pad\n", &iova);
+
+	if (int_status & ~RK_MMU_IRQ_MASK)
+		dev_err(iommu->dev, "unexpected int_status: %#08x\n",
+			int_status);
+
+	rk_iommu_write(iommu, RK_MMU_INT_CLEAR, int_status);
+
+	return IRQ_HANDLED;
+}
+
+static phys_addr_t rk_iommu_iova_to_phys(struct iommu_domain *domain,
+					 dma_addr_t iova)
+{
+	struct rk_iommu_domain *rk_domain = domain->priv;
+	unsigned long flags;
+	phys_addr_t pt_phys, phys = 0;
+	u32 dte, pte;
+	u32 *page_table;
+
+	spin_lock_irqsave(&rk_domain->dt_lock, flags);
+
+	dte = rk_domain->dt[rk_iova_dte_index(iova)];
+	if (!rk_dte_is_pt_valid(dte))
+		goto out;
+
+	pt_phys = rk_dte_pt_address(dte);
+	page_table = (u32 *)phys_to_virt(pt_phys);
+	pte = page_table[rk_iova_pte_index(iova)];
+	if (!rk_pte_is_page_valid(pte))
+		goto out;
+
+	phys = rk_pte_page_address(pte) + rk_iova_page_offset(iova);
+out:
+	spin_unlock_irqrestore(&rk_domain->dt_lock, flags);
+
+	return phys;
+}
+
+static void rk_iommu_zap_iova(struct rk_iommu_domain *rk_domain,
+			      dma_addr_t iova, size_t size)
+{
+	struct list_head *pos;
+	unsigned long flags;
+
+	/* shootdown these iova from all iommus using this domain */
+	spin_lock_irqsave(&rk_domain->iommus_lock, flags);
+	list_for_each(pos, &rk_domain->iommus) {
+		struct rk_iommu *iommu;
+		iommu = list_entry(pos, struct rk_iommu, node);
+		rk_iommu_zap_lines(iommu, iova, size);
+	}
+	spin_unlock_irqrestore(&rk_domain->iommus_lock, flags);
+}
+
+static u32 *rk_dte_get_page_table(struct rk_iommu_domain *rk_domain,
+				  dma_addr_t iova)
+{
+	u32 *page_table, *dte_addr;
+	u32 dte;
+	phys_addr_t pt_phys;
+
+	assert_spin_locked(&rk_domain->dt_lock);
+
+	dte_addr = &rk_domain->dt[rk_iova_dte_index(iova)];
+	dte = *dte_addr;
+	if (rk_dte_is_pt_valid(dte))
+		goto done;
+
+	page_table = (u32 *)get_zeroed_page(GFP_ATOMIC | GFP_DMA32);
+	if (!page_table)
+		return ERR_PTR(-ENOMEM);
+
+	dte = rk_mk_dte(page_table);
+	*dte_addr = dte;
+
+	rk_table_flush(page_table, NUM_PT_ENTRIES);
+	rk_table_flush(dte_addr, 1);
+
+	/*
+	 * Zap the first iova of newly allocated page table so iommu evicts
+	 * old cached value of new dte from the iotlb.
+	 */
+	rk_iommu_zap_iova(rk_domain, iova, SPAGE_SIZE);
+
+done:
+	pt_phys = rk_dte_pt_address(dte);
+	return (u32 *)phys_to_virt(pt_phys);
+}
+
+static size_t rk_iommu_unmap_iova(struct rk_iommu_domain *rk_domain,
+				  u32 *pte_addr, dma_addr_t iova, size_t size)
+{
+	unsigned int pte_count;
+	unsigned int pte_total = size / SPAGE_SIZE;
+
+	assert_spin_locked(&rk_domain->dt_lock);
+
+	for (pte_count = 0; pte_count < pte_total; pte_count++) {
+		u32 pte = pte_addr[pte_count];
+		if (!rk_pte_is_page_valid(pte))
+			break;
+
+		pte_addr[pte_count] = rk_mk_pte_invalid(pte);
+	}
+
+	rk_table_flush(pte_addr, pte_count);
+
+	return pte_count * SPAGE_SIZE;
+}
+
+static int rk_iommu_map_iova(struct rk_iommu_domain *rk_domain, u32 *pte_addr,
+			     dma_addr_t iova, phys_addr_t paddr, size_t size,
+			     int prot)
+{
+	unsigned int pte_count;
+	unsigned int pte_total = size / SPAGE_SIZE;
+	phys_addr_t page_phys;
+
+	assert_spin_locked(&rk_domain->dt_lock);
+
+	for (pte_count = 0; pte_count < pte_total; pte_count++) {
+		u32 pte = pte_addr[pte_count];
+
+		if (rk_pte_is_page_valid(pte))
+			goto unwind;
+
+		pte_addr[pte_count] = rk_mk_pte(paddr, prot);
+
+		paddr += SPAGE_SIZE;
+	}
+
+	rk_table_flush(pte_addr, pte_count);
+
+	return 0;
+unwind:
+	/* Unmap the range of iovas that we just mapped */
+	rk_iommu_unmap_iova(rk_domain, pte_addr, iova, pte_count * SPAGE_SIZE);
+
+	iova += pte_count * SPAGE_SIZE;
+	page_phys = rk_pte_page_address(pte_addr[pte_count]);
+	pr_err("iova: %pad already mapped to %pa cannot remap to phys: %pa prot: %#x\n",
+	       &iova, &page_phys, &paddr, prot);
+
+	return -EADDRINUSE;
+}
+
+static int rk_iommu_map(struct iommu_domain *domain, unsigned long _iova,
+			phys_addr_t paddr, size_t size, int prot)
+{
+	struct rk_iommu_domain *rk_domain = domain->priv;
+	unsigned long flags;
+	dma_addr_t iova = (dma_addr_t)_iova;
+	u32 *page_table, *pte_addr;
+	int ret;
+
+	spin_lock_irqsave(&rk_domain->dt_lock, flags);
+
+	/*
+	 * pgsize_bitmap specifies iova sizes that fit in one page table
+	 * (1024 4-KiB pages = 4 MiB).
+	 * So, size will always be 4096 <= size <= 4194304.
+	 * Since iommu_map() guarantees that both iova and size will be
+	 * aligned, we will always only be mapping from a single dte here.
+	 */
+	page_table = rk_dte_get_page_table(rk_domain, iova);
+	if (IS_ERR(page_table)) {
+		spin_unlock_irqrestore(&rk_domain->dt_lock, flags);
+		return PTR_ERR(page_table);
+	}
+
+	pte_addr = &page_table[rk_iova_pte_index(iova)];
+	ret = rk_iommu_map_iova(rk_domain, pte_addr, iova, paddr, size, prot);
+	spin_unlock_irqrestore(&rk_domain->dt_lock, flags);
+
+	return ret;
+}
+
+static size_t rk_iommu_unmap(struct iommu_domain *domain, unsigned long _iova,
+			     size_t size)
+{
+	struct rk_iommu_domain *rk_domain = domain->priv;
+	unsigned long flags;
+	dma_addr_t iova = (dma_addr_t)_iova;
+	phys_addr_t pt_phys;
+	u32 dte;
+	u32 *pte_addr;
+	size_t unmap_size;
+
+	spin_lock_irqsave(&rk_domain->dt_lock, flags);
+
+	/*
+	 * pgsize_bitmap specifies iova sizes that fit in one page table
+	 * (1024 4-KiB pages = 4 MiB).
+	 * So, size will always be 4096 <= size <= 4194304.
+	 * Since iommu_unmap() guarantees that both iova and size will be
+	 * aligned, we will always only be unmapping from a single dte here.
+	 */
+	dte = rk_domain->dt[rk_iova_dte_index(iova)];
+	/* Just return 0 if iova is unmapped */
+	if (!rk_dte_is_pt_valid(dte)) {
+		spin_unlock_irqrestore(&rk_domain->dt_lock, flags);
+		return 0;
+	}
+
+	pt_phys = rk_dte_pt_address(dte);
+	pte_addr = (u32 *)phys_to_virt(pt_phys) + rk_iova_pte_index(iova);
+	unmap_size = rk_iommu_unmap_iova(rk_domain, pte_addr, iova, size);
+
+	spin_unlock_irqrestore(&rk_domain->dt_lock, flags);
+
+	/* Shootdown iotlb entries for iova range that was just unmapped */
+	rk_iommu_zap_iova(rk_domain, iova, unmap_size);
+
+	return unmap_size;
+}
+
+static struct rk_iommu *rk_iommu_from_dev(struct device *dev)
+{
+	struct iommu_group *group;
+	struct device *iommu_dev;
+	struct rk_iommu *rk_iommu;
+
+	group = iommu_group_get(dev);
+	if (!group)
+		return NULL;
+	iommu_dev = iommu_group_get_iommudata(group);
+	rk_iommu = dev_get_drvdata(iommu_dev);
+	iommu_group_put(group);
+
+	return rk_iommu;
+}
+
+static int rk_iommu_attach_device(struct iommu_domain *domain,
+				  struct device *dev)
+{
+	struct rk_iommu *iommu;
+	struct rk_iommu_domain *rk_domain = domain->priv;
+	unsigned long flags;
+	int ret;
+	phys_addr_t dte_addr;
+
+	/*
+	 * Allow 'virtual devices' (e.g., drm) to attach to domain.
+	 * Such a device does not belong to an iommu group.
+	 */
+	iommu = rk_iommu_from_dev(dev);
+	if (!iommu)
+		return 0;
+
+	ret = rk_iommu_enable_stall(iommu);
+	if (ret)
+		return ret;
+
+	ret = rk_iommu_force_reset(iommu);
+	if (ret)
+		return ret;
+
+	iommu->domain = domain;
+
+	ret = devm_request_irq(dev, iommu->irq, rk_iommu_irq,
+			       IRQF_SHARED, dev_name(dev), iommu);
+	if (ret)
+		return ret;
+
+	dte_addr = virt_to_phys(rk_domain->dt);
+	rk_iommu_write(iommu, RK_MMU_DTE_ADDR, dte_addr);
+	rk_iommu_command(iommu, RK_MMU_CMD_ZAP_CACHE);
+	rk_iommu_write(iommu, RK_MMU_INT_MASK, RK_MMU_IRQ_MASK);
+
+	ret = rk_iommu_enable_paging(iommu);
+	if (ret)
+		return ret;
+
+	spin_lock_irqsave(&rk_domain->iommus_lock, flags);
+	list_add_tail(&iommu->node, &rk_domain->iommus);
+	spin_unlock_irqrestore(&rk_domain->iommus_lock, flags);
+
+	dev_info(dev, "Attached to iommu domain\n");
+
+	rk_iommu_disable_stall(iommu);
+
+	return 0;
+}
+
+static void rk_iommu_detach_device(struct iommu_domain *domain,
+				   struct device *dev)
+{
+	struct rk_iommu *iommu;
+	struct rk_iommu_domain *rk_domain = domain->priv;
+	unsigned long flags;
+
+	/* Allow 'virtual devices' (eg drm) to detach from domain */
+	iommu = rk_iommu_from_dev(dev);
+	if (!iommu)
+		return;
+
+	spin_lock_irqsave(&rk_domain->iommus_lock, flags);
+	list_del_init(&iommu->node);
+	spin_unlock_irqrestore(&rk_domain->iommus_lock, flags);
+
+	/* Ignore error while disabling, just keep going */
+	rk_iommu_enable_stall(iommu);
+	rk_iommu_disable_paging(iommu);
+	rk_iommu_write(iommu, RK_MMU_INT_MASK, 0);
+	rk_iommu_write(iommu, RK_MMU_DTE_ADDR, 0);
+	rk_iommu_disable_stall(iommu);
+
+	devm_free_irq(dev, iommu->irq, iommu);
+
+	iommu->domain = NULL;
+
+	dev_info(dev, "Detached from iommu domain\n");
+}
+
+static int rk_iommu_domain_init(struct iommu_domain *domain)
+{
+	struct rk_iommu_domain *rk_domain;
+
+	rk_domain = kzalloc(sizeof(*rk_domain), GFP_KERNEL);
+	if (!rk_domain)
+		return -ENOMEM;
+
+	/*
+	 * rk32xx iommus use a 2 level pagetable.
+	 * Each level1 (dt) and level2 (pt) table has 1024 4-byte entries.
+	 * Allocate one 4 KiB page for each table.
+	 */
+	rk_domain->dt = (u32 *)get_zeroed_page(GFP_KERNEL | GFP_DMA32);
+	if (!rk_domain->dt)
+		goto err_dt;
+
+	rk_table_flush(rk_domain->dt, NUM_DT_ENTRIES);
+
+	spin_lock_init(&rk_domain->iommus_lock);
+	spin_lock_init(&rk_domain->dt_lock);
+	INIT_LIST_HEAD(&rk_domain->iommus);
+
+	domain->priv = rk_domain;
+
+	return 0;
+err_dt:
+	kfree(rk_domain);
+	return -ENOMEM;
+}
+
+static void rk_iommu_domain_destroy(struct iommu_domain *domain)
+{
+	struct rk_iommu_domain *rk_domain = domain->priv;
+	int i;
+
+	WARN_ON(!list_empty(&rk_domain->iommus));
+
+	for (i = 0; i < NUM_DT_ENTRIES; i++) {
+		u32 dte = rk_domain->dt[i];
+		if (rk_dte_is_pt_valid(dte)) {
+			phys_addr_t pt_phys = rk_dte_pt_address(dte);
+			u32 *page_table = phys_to_virt(pt_phys);
+			free_page((unsigned long)page_table);
+		}
+	}
+
+	free_page((unsigned long)rk_domain->dt);
+	kfree(domain->priv);
+	domain->priv = NULL;
+}
+
+static bool rk_iommu_is_dev_iommu_master(struct device *dev)
+{
+	struct device_node *np = dev->of_node;
+	int ret;
+
+	/*
+	 * An iommu master has an iommus property containing a list of phandles
+	 * to iommu nodes, each with an #iommu-cells property with value 0.
+	 */
+	ret = of_count_phandle_with_args(np, "iommus", "#iommu-cells");
+	return (ret > 0);
+}
+
+static int rk_iommu_group_set_iommudata(struct iommu_group *group,
+					struct device *dev)
+{
+	struct device_node *np = dev->of_node;
+	struct platform_device *pd;
+	int ret;
+	struct of_phandle_args args;
+
+	/*
+	 * An iommu master has an iommus property containing a list of phandles
+	 * to iommu nodes, each with an #iommu-cells property with value 0.
+	 */
+	ret = of_parse_phandle_with_args(np, "iommus", "#iommu-cells", 0,
+					 &args);
+	if (ret) {
+		dev_err(dev, "of_parse_phandle_with_args(%s) => %d\n",
+			np->full_name, ret);
+		return ret;
+	}
+	if (args.args_count != 0) {
+		dev_err(dev, "incorrect number of iommu params found for %s (found %d, expected 0)\n",
+			args.np->full_name, args.args_count);
+		return -EINVAL;
+	}
+
+	pd = of_find_device_by_node(args.np);
+	of_node_put(args.np);
+	if (!pd) {
+		dev_err(dev, "iommu %s not found\n", args.np->full_name);
+		return -EPROBE_DEFER;
+	}
+
+	/* TODO(djkurtz): handle multiple slave iommus for a single master */
+	iommu_group_set_iommudata(group, &pd->dev, NULL);
+
+	return 0;
+}
+
+static int rk_iommu_add_device(struct device *dev)
+{
+	struct iommu_group *group;
+	int ret;
+
+	if (!rk_iommu_is_dev_iommu_master(dev))
+		return -ENODEV;
+
+	group = iommu_group_get(dev);
+	if (!group) {
+		group = iommu_group_alloc();
+		if (IS_ERR(group)) {
+			dev_err(dev, "Failed to allocate IOMMU group\n");
+			return PTR_ERR(group);
+		}
+	}
+
+	ret = iommu_group_add_device(group, dev);
+	if (ret)
+		goto err_put_group;
+
+	ret = rk_iommu_group_set_iommudata(group, dev);
+	if (ret)
+		goto err_remove_device;
+
+	iommu_group_put(group);
+
+	return 0;
+
+err_remove_device:
+	iommu_group_remove_device(dev);
+err_put_group:
+	iommu_group_put(group);
+	return ret;
+}
+
+static void rk_iommu_remove_device(struct device *dev)
+{
+	if (!rk_iommu_is_dev_iommu_master(dev))
+		return;
+
+	iommu_group_remove_device(dev);
+}
+
+static const struct iommu_ops rk_iommu_ops = {
+	.domain_init = rk_iommu_domain_init,
+	.domain_destroy = rk_iommu_domain_destroy,
+	.attach_dev = rk_iommu_attach_device,
+	.detach_dev = rk_iommu_detach_device,
+	.map = rk_iommu_map,
+	.unmap = rk_iommu_unmap,
+	.add_device = rk_iommu_add_device,
+	.remove_device = rk_iommu_remove_device,
+	.iova_to_phys = rk_iommu_iova_to_phys,
+	.pgsize_bitmap = RK_IOMMU_PGSIZE_BITMAP,
+};
+
+static int rk_iommu_probe(struct platform_device *pdev)
+{
+	struct device *dev = &pdev->dev;
+	struct rk_iommu *iommu;
+	struct resource *res;
+
+	iommu = devm_kzalloc(dev, sizeof(*iommu), GFP_KERNEL);
+	if (!iommu)
+		return -ENOMEM;
+
+	platform_set_drvdata(pdev, iommu);
+	iommu->dev = dev;
+
+	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+	iommu->base = devm_ioremap_resource(&pdev->dev, res);
+	if (IS_ERR(iommu->base))
+		return PTR_ERR(iommu->base);
+
+	iommu->irq = platform_get_irq(pdev, 0);
+	if (iommu->irq < 0) {
+		dev_err(dev, "Failed to get IRQ, %d\n", iommu->irq);
+		return -ENXIO;
+	}
+
+	return 0;
+}
+
+static int rk_iommu_remove(struct platform_device *pdev)
+{
+	return 0;
+}
+
+#ifdef CONFIG_OF
+static const struct of_device_id rk_iommu_dt_ids[] = {
+	{ .compatible = "rockchip,iommu" },
+	{ /* sentinel */ }
+};
+MODULE_DEVICE_TABLE(of, rk_iommu_dt_ids);
+#endif
+
+static struct platform_driver rk_iommu_driver = {
+	.probe = rk_iommu_probe,
+	.remove = rk_iommu_remove,
+	.driver = {
+		   .name = "rk_iommu",
+		   .owner = THIS_MODULE,
+		   .of_match_table = of_match_ptr(rk_iommu_dt_ids),
+	},
+};
+
+static int __init rk_iommu_init(void)
+{
+	int ret;
+
+	ret = bus_set_iommu(&platform_bus_type, &rk_iommu_ops);
+	if (ret)
+		return ret;
+
+	return platform_driver_register(&rk_iommu_driver);
+}
+static void __exit rk_iommu_exit(void)
+{
+	platform_driver_unregister(&rk_iommu_driver);
+}
+
+subsys_initcall(rk_iommu_init);
+module_exit(rk_iommu_exit);
+
+MODULE_DESCRIPTION("IOMMU API for Rockchip");
+MODULE_AUTHOR("Simon Xue <xxm@rock-chips.com> and Daniel Kurtz <djkurtz@chromium.org>");
+MODULE_ALIAS("platform:rockchip-iommu");
+MODULE_LICENSE("GPL v2");