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Subject[PATCH v5 1/5] iommu/arm-smmu: add NVIDIA implementation for dual ARM MMU-500 usage
Date
NVIDIA's Tegra194 soc uses two ARM MMU-500s together to interleave
IOVA accesses across them.
Add NVIDIA implementation for dual ARM MMU-500s and add new compatible
string for Tegra194 soc.

Signed-off-by: Krishna Reddy <vdumpa@nvidia.com>
---
MAINTAINERS | 2 +
drivers/iommu/Makefile | 2 +-
drivers/iommu/arm-smmu-impl.c | 3 +
drivers/iommu/arm-smmu-nvidia.c | 161 ++++++++++++++++++++++++++++++++
drivers/iommu/arm-smmu.h | 1 +
5 files changed, 168 insertions(+), 1 deletion(-)
create mode 100644 drivers/iommu/arm-smmu-nvidia.c

diff --git a/MAINTAINERS b/MAINTAINERS
index ecc0749810b0..0d8c966ecf17 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -16560,9 +16560,11 @@ F: drivers/i2c/busses/i2c-tegra.c

TEGRA IOMMU DRIVERS
M: Thierry Reding <thierry.reding@gmail.com>
+R: Krishna Reddy <vdumpa@nvidia.com>
L: linux-tegra@vger.kernel.org
S: Supported
F: drivers/iommu/tegra*
+F: drivers/iommu/arm-smmu-nvidia.c

TEGRA KBC DRIVER
M: Laxman Dewangan <ldewangan@nvidia.com>
diff --git a/drivers/iommu/Makefile b/drivers/iommu/Makefile
index 57cf4ba5e27c..35542df00da7 100644
--- a/drivers/iommu/Makefile
+++ b/drivers/iommu/Makefile
@@ -15,7 +15,7 @@ obj-$(CONFIG_AMD_IOMMU) += amd_iommu.o amd_iommu_init.o amd_iommu_quirks.o
obj-$(CONFIG_AMD_IOMMU_DEBUGFS) += amd_iommu_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-qcom.o arm-smmu-nvidia.o
obj-$(CONFIG_ARM_SMMU_V3) += arm-smmu-v3.o
obj-$(CONFIG_DMAR_TABLE) += 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 74d97a886e93..dcdd513323aa 100644
--- a/drivers/iommu/arm-smmu-impl.c
+++ b/drivers/iommu/arm-smmu-impl.c
@@ -158,6 +158,9 @@ struct arm_smmu_device *arm_smmu_impl_init(struct arm_smmu_device *smmu)
*/
switch (smmu->model) {
case ARM_MMU500:
+ if (of_device_is_compatible(smmu->dev->of_node,
+ "nvidia,tegra194-smmu-500"))
+ return nvidia_smmu_impl_init(smmu);
smmu->impl = &arm_mmu500_impl;
break;
case CAVIUM_SMMUV2:
diff --git a/drivers/iommu/arm-smmu-nvidia.c b/drivers/iommu/arm-smmu-nvidia.c
new file mode 100644
index 000000000000..dafc293a4521
--- /dev/null
+++ b/drivers/iommu/arm-smmu-nvidia.c
@@ -0,0 +1,161 @@
+// SPDX-License-Identifier: GPL-2.0-only
+// Nvidia ARM SMMU v2 implementation quirks
+// Copyright (C) 2019 NVIDIA CORPORATION. All rights reserved.
+
+#define pr_fmt(fmt) "nvidia-smmu: " fmt
+
+#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 for Interleaved IOVA accesses and
+ * used by Non-Isochronous Hw devices for SMMU translations.
+ * Third one is used for SMMU translations from Isochronous HW devices.
+ * It is possible to use this Implementation to program either
+ * all three or two of the instances identically as desired through
+ * DT node.
+ *
+ * Programming all the three instances identically comes with redundant tlb
+ * invalidations as all three never need to be tlb invalidated for a HW device.
+ *
+ * When Linux Kernel supports multiple SMMU devices, The SMMU device used for
+ * Isochornous HW devices should be added as a separate ARM MMU-500 device
+ * in DT and be programmed independently for efficient tlb invalidates.
+ *
+ */
+#define MAX_SMMU_INSTANCES 3
+
+#define TLB_LOOP_TIMEOUT 1000000 /* 1s! */
+#define TLB_SPIN_COUNT 10
+
+struct nvidia_smmu {
+ struct arm_smmu_device smmu;
+ unsigned int num_inst;
+ void __iomem *bases[MAX_SMMU_INSTANCES];
+};
+
+#define to_nvidia_smmu(s) container_of(s, struct nvidia_smmu, smmu)
+
+#define nsmmu_page(smmu, inst, page) \
+ (((inst) ? to_nvidia_smmu(smmu)->bases[(inst)] : smmu->base) + \
+ ((page) << smmu->pgshift))
+
+static u32 nsmmu_read_reg(struct arm_smmu_device *smmu,
+ int page, int offset)
+{
+ return readl_relaxed(nsmmu_page(smmu, 0, page) + offset);
+}
+
+static void nsmmu_write_reg(struct arm_smmu_device *smmu,
+ int page, int offset, u32 val)
+{
+ unsigned int i;
+
+ for (i = 0; i < to_nvidia_smmu(smmu)->num_inst; i++)
+ writel_relaxed(val, nsmmu_page(smmu, i, page) + offset);
+}
+
+static u64 nsmmu_read_reg64(struct arm_smmu_device *smmu,
+ int page, int offset)
+{
+ return readq_relaxed(nsmmu_page(smmu, 0, page) + offset);
+}
+
+static void nsmmu_write_reg64(struct arm_smmu_device *smmu,
+ int page, int offset, u64 val)
+{
+ unsigned int i;
+
+ for (i = 0; i < to_nvidia_smmu(smmu)->num_inst; i++)
+ writeq_relaxed(val, nsmmu_page(smmu, i, page) + offset);
+}
+
+static void nsmmu_tlb_sync(struct arm_smmu_device *smmu, int page,
+ int sync, int status)
+{
+ u32 reg;
+ unsigned int i;
+ unsigned int spin_cnt, delay;
+
+ arm_smmu_writel(smmu, page, sync, 0);
+
+ for (delay = 1; delay < TLB_LOOP_TIMEOUT; delay *= 2) {
+ for (spin_cnt = TLB_SPIN_COUNT; spin_cnt > 0; spin_cnt--) {
+ reg = 0;
+ for (i = 0; i < to_nvidia_smmu(smmu)->num_inst; i++) {
+ reg |= readl_relaxed(
+ nsmmu_page(smmu, i, page) + status);
+ }
+ if (!(reg & 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 nsmmu_reset(struct arm_smmu_device *smmu)
+{
+ u32 reg;
+ unsigned int i;
+
+ for (i = 0; i < to_nvidia_smmu(smmu)->num_inst; i++) {
+ /* clear global FSR */
+ reg = readl_relaxed(nsmmu_page(smmu, i, ARM_SMMU_GR0) +
+ ARM_SMMU_GR0_sGFSR);
+ writel_relaxed(reg, nsmmu_page(smmu, i, ARM_SMMU_GR0) +
+ ARM_SMMU_GR0_sGFSR);
+ }
+
+ return 0;
+}
+
+static const struct arm_smmu_impl nvidia_smmu_impl = {
+ .read_reg = nsmmu_read_reg,
+ .write_reg = nsmmu_write_reg,
+ .read_reg64 = nsmmu_read_reg64,
+ .write_reg64 = nsmmu_write_reg64,
+ .reset = nsmmu_reset,
+ .tlb_sync = nsmmu_tlb_sync,
+};
+
+struct arm_smmu_device *nvidia_smmu_impl_init(struct arm_smmu_device *smmu)
+{
+ unsigned int i;
+ struct nvidia_smmu *nsmmu;
+ struct resource *res;
+ struct device *dev = smmu->dev;
+ struct platform_device *pdev = to_platform_device(smmu->dev);
+
+ nsmmu = devm_kzalloc(smmu->dev, sizeof(*nsmmu), GFP_KERNEL);
+ if (!nsmmu)
+ return ERR_PTR(-ENOMEM);
+
+ nsmmu->smmu = *smmu;
+ /* Instance 0 is ioremapped by arm-smmu.c */
+ nsmmu->num_inst = 1;
+
+ for (i = 1; i < MAX_SMMU_INSTANCES; i++) {
+ res = platform_get_resource(pdev, IORESOURCE_MEM, i);
+ if (!res)
+ break;
+ nsmmu->bases[i] = devm_ioremap_resource(dev, res);
+ if (IS_ERR(nsmmu->bases[i]))
+ return (struct arm_smmu_device *)nsmmu->bases[i];
+ nsmmu->num_inst++;
+ }
+
+ nsmmu->smmu.impl = &nvidia_smmu_impl;
+ devm_kfree(smmu->dev, smmu);
+ pr_info("NVIDIA ARM SMMU Implementation, Instances=%d\n",
+ nsmmu->num_inst);
+
+ return &nsmmu->smmu;
+}
diff --git a/drivers/iommu/arm-smmu.h b/drivers/iommu/arm-smmu.h
index 8d1cd54d82a6..67c3c6f5c49e 100644
--- a/drivers/iommu/arm-smmu.h
+++ b/drivers/iommu/arm-smmu.h
@@ -450,6 +450,7 @@ static inline void arm_smmu_writeq(struct arm_smmu_device *smmu, int page,

struct arm_smmu_device *arm_smmu_impl_init(struct arm_smmu_device *smmu);
struct arm_smmu_device *qcom_smmu_impl_init(struct arm_smmu_device *smmu);
+struct arm_smmu_device *nvidia_smmu_impl_init(struct arm_smmu_device *smmu);

int arm_mmu500_reset(struct arm_smmu_device *smmu);

--
2.26.2
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