NVIDIA's Tegra194 SoC has three ARM MMU-500 instances.
It uses two of the ARM MMU-500s together to interleave IOVA
accesses across them and must be programmed identically.
This implementation supports programming the two ARM MMU-500s
that must be programmed identically.

The third ARM MMU-500 instance is supported by standard
arm-smmu.c driver itself.

Signed-off-by: Krishna Reddy <vdu...@nvidia.com>
---
 MAINTAINERS                     |   2 +
 drivers/iommu/Makefile          |   2 +-
 drivers/iommu/arm-smmu-impl.c   |   3 +
 drivers/iommu/arm-smmu-nvidia.c | 179 ++++++++++++++++++++++++++++++++
 drivers/iommu/arm-smmu.c        |   1 +
 drivers/iommu/arm-smmu.h        |   1 +
 6 files changed, 187 insertions(+), 1 deletion(-)
 create mode 100644 drivers/iommu/arm-smmu-nvidia.c

diff --git a/MAINTAINERS b/MAINTAINERS
index c23352059a6b..534cedaf8e55 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -16811,8 +16811,10 @@ F:     drivers/i2c/busses/i2c-tegra.c
 
 TEGRA IOMMU DRIVERS
 M:     Thierry Reding <thierry.red...@gmail.com>
+R:     Krishna Reddy <vdu...@nvidia.com>
 L:     linux-te...@vger.kernel.org
 S:     Supported
+F:     drivers/iommu/arm-smmu-nvidia.c
 F:     drivers/iommu/tegra*
 
 TEGRA KBC DRIVER
diff --git a/drivers/iommu/Makefile b/drivers/iommu/Makefile
index 342190196dfb..2b8203db73ec 100644
--- a/drivers/iommu/Makefile
+++ b/drivers/iommu/Makefile
@@ -15,7 +15,7 @@ obj-$(CONFIG_AMD_IOMMU) += amd/iommu.o amd/init.o amd/quirks.o
 obj-$(CONFIG_AMD_IOMMU_DEBUGFS) += amd/debugfs.o
 obj-$(CONFIG_AMD_IOMMU_V2) += amd/iommu_v2.o
 obj-$(CONFIG_ARM_SMMU) += arm_smmu.o
-arm_smmu-objs += arm-smmu.o arm-smmu-impl.o arm-smmu-qcom.o
+arm_smmu-objs += arm-smmu.o arm-smmu-impl.o arm-smmu-nvidia.o arm-smmu-qcom.o
 obj-$(CONFIG_ARM_SMMU_V3) += arm-smmu-v3.o
 obj-$(CONFIG_DMAR_TABLE) += intel/dmar.o
 obj-$(CONFIG_INTEL_IOMMU) += intel/iommu.o intel/pasid.o
diff --git a/drivers/iommu/arm-smmu-impl.c b/drivers/iommu/arm-smmu-impl.c
index c75b9d957b70..f15571d05474 100644
--- a/drivers/iommu/arm-smmu-impl.c
+++ b/drivers/iommu/arm-smmu-impl.c
@@ -171,6 +171,9 @@ struct arm_smmu_device *arm_smmu_impl_init(struct 
arm_smmu_device *smmu)
        if (of_property_read_bool(np, "calxeda,smmu-secure-config-access"))
                smmu->impl = &calxeda_impl;
 
+       if (of_device_is_compatible(np, "nvidia,tegra194-smmu"))
+               return nvidia_smmu_impl_init(smmu);
+
        if (of_device_is_compatible(np, "qcom,sdm845-smmu-500") ||
            of_device_is_compatible(np, "qcom,sc7180-smmu-500"))
                return qcom_smmu_impl_init(smmu);
diff --git a/drivers/iommu/arm-smmu-nvidia.c b/drivers/iommu/arm-smmu-nvidia.c
new file mode 100644
index 000000000000..2f55e5793d34
--- /dev/null
+++ b/drivers/iommu/arm-smmu-nvidia.c
@@ -0,0 +1,179 @@
+// SPDX-License-Identifier: GPL-2.0-only
+// Copyright (C) 2019-2020 NVIDIA CORPORATION.  All rights reserved.
+
+#include <linux/bitfield.h>
+#include <linux/delay.h>
+#include <linux/of.h>
+#include <linux/platform_device.h>
+#include <linux/slab.h>
+
+#include "arm-smmu.h"
+
+/*
+ * Tegra194 has three ARM MMU-500 Instances.
+ * Two of them are used together and must be programmed identically for
+ * interleaved IOVA accesses across them and translates accesses from
+ * non-isochronous HW devices.
+ * Third one is used for translating accesses from isochronous HW devices.
+ * This implementation supports programming of the two instances that must
+ * be programmed identically.
+ * The third instance usage is through standard arm-smmu driver itself and
+ * is out of scope of this implementation.
+ */
+#define NUM_SMMU_INSTANCES 2
+
+struct nvidia_smmu {
+       struct arm_smmu_device  smmu;
+       void __iomem            *bases[NUM_SMMU_INSTANCES];
+};
+
+static inline void __iomem *nvidia_smmu_page(struct arm_smmu_device *smmu,
+                                            unsigned int inst, int page)
+{
+       struct nvidia_smmu *nvidia_smmu;
+
+       nvidia_smmu = container_of(smmu, struct nvidia_smmu, smmu);
+       return nvidia_smmu->bases[inst] + (page << smmu->pgshift);
+}
+
+static u32 nvidia_smmu_read_reg(struct arm_smmu_device *smmu,
+                               int page, int offset)
+{
+       void __iomem *reg = nvidia_smmu_page(smmu, 0, page) + offset;
+
+       return readl_relaxed(reg);
+}
+
+static void nvidia_smmu_write_reg(struct arm_smmu_device *smmu,
+                                 int page, int offset, u32 val)
+{
+       unsigned int i;
+
+       for (i = 0; i < NUM_SMMU_INSTANCES; i++) {
+               void __iomem *reg = nvidia_smmu_page(smmu, i, page) + offset;
+
+               writel_relaxed(val, reg);
+       }
+}
+
+static u64 nvidia_smmu_read_reg64(struct arm_smmu_device *smmu,
+                                 int page, int offset)
+{
+       void __iomem *reg = nvidia_smmu_page(smmu, 0, page) + offset;
+
+       return readq_relaxed(reg);
+}
+
+static void nvidia_smmu_write_reg64(struct arm_smmu_device *smmu,
+                                   int page, int offset, u64 val)
+{
+       unsigned int i;
+
+       for (i = 0; i < NUM_SMMU_INSTANCES; i++) {
+               void __iomem *reg = nvidia_smmu_page(smmu, i, page) + offset;
+
+               writeq_relaxed(val, reg);
+       }
+}
+
+static void nvidia_smmu_tlb_sync(struct arm_smmu_device *smmu, int page,
+                                int sync, int status)
+{
+       unsigned int delay;
+
+       arm_smmu_writel(smmu, page, sync, 0);
+
+       for (delay = 1; delay < TLB_LOOP_TIMEOUT; delay *= 2) {
+               unsigned int spin_cnt;
+
+               for (spin_cnt = TLB_SPIN_COUNT; spin_cnt > 0; spin_cnt--) {
+                       u32 val = 0;
+                       unsigned int i;
+
+                       for (i = 0; i < NUM_SMMU_INSTANCES; i++) {
+                               void __iomem *reg;
+
+                               reg = nvidia_smmu_page(smmu, i, page) + status;
+                               val |= readl_relaxed(reg);
+                       }
+
+                       if (!(val & ARM_SMMU_sTLBGSTATUS_GSACTIVE))
+                               return;
+
+                       cpu_relax();
+               }
+
+               udelay(delay);
+       }
+
+       dev_err_ratelimited(smmu->dev,
+                           "TLB sync timed out -- SMMU may be deadlocked\n");
+}
+
+static int nvidia_smmu_reset(struct arm_smmu_device *smmu)
+{
+       unsigned int i;
+
+       for (i = 0; i < NUM_SMMU_INSTANCES; i++) {
+               u32 val;
+               void __iomem *reg = nvidia_smmu_page(smmu, i, ARM_SMMU_GR0) +
+                                   ARM_SMMU_GR0_sGFSR;
+
+               /* clear global FSR */
+               val = readl_relaxed(reg);
+               writel_relaxed(val, reg);
+       }
+
+       return 0;
+}
+
+static const struct arm_smmu_impl nvidia_smmu_impl = {
+       .read_reg = nvidia_smmu_read_reg,
+       .write_reg = nvidia_smmu_write_reg,
+       .read_reg64 = nvidia_smmu_read_reg64,
+       .write_reg64 = nvidia_smmu_write_reg64,
+       .reset = nvidia_smmu_reset,
+       .tlb_sync = nvidia_smmu_tlb_sync,
+};
+
+struct arm_smmu_device *nvidia_smmu_impl_init(struct arm_smmu_device *smmu)
+{
+       struct resource *res;
+       struct device *dev = smmu->dev;
+       struct nvidia_smmu *nvidia_smmu;
+       struct platform_device *pdev = to_platform_device(dev);
+
+       nvidia_smmu = devm_kzalloc(dev, sizeof(*nvidia_smmu), GFP_KERNEL);
+       if (!nvidia_smmu)
+               return ERR_PTR(-ENOMEM);
+
+       /*
+        * Copy the data from struct arm_smmu_device *smmu allocated in
+        * arm-smmu.c. The smmu from struct nvidia_smmu replaces the smmu
+        * pointer used in arm-smmu.c once this function returns.
+        * This is necessary to derive nvidia_smmu from smmu pointer passed
+        * through arm_smmu_impl function calls subsequently.
+        */
+       nvidia_smmu->smmu = *smmu;
+       /* Instance 0 is ioremapped by arm-smmu.c. */
+       nvidia_smmu->bases[0] = smmu->base;
+
+       res = platform_get_resource(pdev, IORESOURCE_MEM, 1);
+       if (!res)
+               return ERR_PTR(-ENODEV);
+
+       nvidia_smmu->bases[1] = devm_ioremap_resource(dev, res);
+       if (IS_ERR(nvidia_smmu->bases[1]))
+               return ERR_CAST(nvidia_smmu->bases[1]);
+
+       nvidia_smmu->smmu.impl = &nvidia_smmu_impl;
+
+       /*
+        * Free the struct arm_smmu_device *smmu allocated in arm-smmu.c.
+        * Once this function returns, arm-smmu.c would use arm_smmu_device
+        * allocated as part of struct nvidia_smmu.
+        */
+       devm_kfree(dev, smmu);
+
+       return &nvidia_smmu->smmu;
+}
diff --git a/drivers/iommu/arm-smmu.c b/drivers/iommu/arm-smmu.c
index e03e873d3bca..c123a5814f70 100644
--- a/drivers/iommu/arm-smmu.c
+++ b/drivers/iommu/arm-smmu.c
@@ -1943,6 +1943,7 @@ static const struct of_device_id arm_smmu_of_match[] = {
        { .compatible = "arm,mmu-401", .data = &arm_mmu401 },
        { .compatible = "arm,mmu-500", .data = &arm_mmu500 },
        { .compatible = "cavium,smmu-v2", .data = &cavium_smmuv2 },
+       { .compatible = "nvidia,smmu-500", .data = &arm_mmu500 },
        { .compatible = "qcom,smmu-v2", .data = &qcom_smmuv2 },
        { },
 };
diff --git a/drivers/iommu/arm-smmu.h b/drivers/iommu/arm-smmu.h
index c7d0122a7c6c..fad63efa1a72 100644
--- a/drivers/iommu/arm-smmu.h
+++ b/drivers/iommu/arm-smmu.h
@@ -452,6 +452,7 @@ static inline void arm_smmu_writeq(struct arm_smmu_device 
*smmu, int page,
        arm_smmu_writeq((s), ARM_SMMU_CB((s), (n)), (o), (v))
 
 struct arm_smmu_device *arm_smmu_impl_init(struct arm_smmu_device *smmu);
+struct arm_smmu_device *nvidia_smmu_impl_init(struct arm_smmu_device *smmu);
 struct arm_smmu_device *qcom_smmu_impl_init(struct arm_smmu_device *smmu);
 
 int arm_mmu500_reset(struct arm_smmu_device *smmu);
-- 
2.26.2

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