From mboxrd@z Thu Jan 1 00:00:00 1970 From: Thierry Reding Subject: Re: [PATCH v6 1/4] iommu/arm-smmu: add NVIDIA implementation for dual ARM MMU-500 usage Date: Tue, 23 Jun 2020 12:29:27 +0200 Message-ID: <20200623102927.GD4098287@ulmo> References: <20200604234414.21912-1-vdumpa@nvidia.com> <20200604234414.21912-2-vdumpa@nvidia.com> Mime-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha256; protocol="application/pgp-signature"; boundary="wLAMOaPNJ0fu1fTG" Return-path: Content-Disposition: inline In-Reply-To: <20200604234414.21912-2-vdumpa-DDmLM1+adcrQT0dZR+AlfA@public.gmane.org> Sender: linux-tegra-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: Krishna Reddy Cc: snikam-DDmLM1+adcrQT0dZR+AlfA@public.gmane.org, mperttunen-DDmLM1+adcrQT0dZR+AlfA@public.gmane.org, bhuntsman-DDmLM1+adcrQT0dZR+AlfA@public.gmane.org, will-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org, joro-zLv9SwRftAIdnm+yROfE0A@public.gmane.org, linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, praithatha-DDmLM1+adcrQT0dZR+AlfA@public.gmane.org, talho-DDmLM1+adcrQT0dZR+AlfA@public.gmane.org, iommu-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org, nicolinc-DDmLM1+adcrQT0dZR+AlfA@public.gmane.org, linux-tegra-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, yhsu-DDmLM1+adcrQT0dZR+AlfA@public.gmane.org, treding-DDmLM1+adcrQT0dZR+AlfA@public.gmane.org, robin.murphy-5wv7dgnIgG8@public.gmane.org, linux-arm-kernel-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@public.gmane.org, bbiswas-DDmLM1+adcrQT0dZR+AlfA@public.gmane.org List-Id: linux-tegra@vger.kernel.org --wLAMOaPNJ0fu1fTG Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Thu, Jun 04, 2020 at 04:44:11PM -0700, Krishna Reddy wrote: > NVIDIA's Tegra194 soc uses two ARM MMU-500s together to interleave s/soc/SoC/ > IOVA accesses across them. > Add NVIDIA implementation for dual ARM MMU-500s and add new compatible > string for Tegra194 soc. Same here. >=20 > Signed-off-by: Krishna Reddy > --- > 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 >=20 > diff --git a/MAINTAINERS b/MAINTAINERS > index 50659d76976b7..118da0893c964 100644 > --- a/MAINTAINERS > +++ b/MAINTAINERS > @@ -16572,9 +16572,11 @@ F: drivers/i2c/busses/i2c-tegra.c > =20 > TEGRA IOMMU DRIVERS > M: Thierry Reding > +R: Krishna Reddy > L: linux-tegra-u79uwXL29TY76Z2rM5mHXA@public.gmane.org > S: Supported > F: drivers/iommu/tegra* > +F: drivers/iommu/arm-smmu-nvidia.c > =20 > TEGRA KBC DRIVER > M: Laxman Dewangan > diff --git a/drivers/iommu/Makefile b/drivers/iommu/Makefile > index 57cf4ba5e27cb..35542df00da72 100644 > --- a/drivers/iommu/Makefile > +++ b/drivers/iommu/Makefile > @@ -15,7 +15,7 @@ obj-$(CONFIG_AMD_IOMMU) +=3D amd_iommu.o amd_iommu_init= =2Eo amd_iommu_quirks.o > obj-$(CONFIG_AMD_IOMMU_DEBUGFS) +=3D amd_iommu_debugfs.o > obj-$(CONFIG_AMD_IOMMU_V2) +=3D amd_iommu_v2.o > obj-$(CONFIG_ARM_SMMU) +=3D arm_smmu.o > -arm_smmu-objs +=3D arm-smmu.o arm-smmu-impl.o arm-smmu-qcom.o > +arm_smmu-objs +=3D arm-smmu.o arm-smmu-impl.o arm-smmu-qcom.o arm-smmu-n= vidia.o > obj-$(CONFIG_ARM_SMMU_V3) +=3D arm-smmu-v3.o > obj-$(CONFIG_DMAR_TABLE) +=3D dmar.o > obj-$(CONFIG_INTEL_IOMMU) +=3D intel-iommu.o intel-pasid.o > diff --git a/drivers/iommu/arm-smmu-impl.c b/drivers/iommu/arm-smmu-impl.c > index c75b9d957b702..52c84c30f83e4 100644 > --- a/drivers/iommu/arm-smmu-impl.c > +++ b/drivers/iommu/arm-smmu-impl.c > @@ -160,6 +160,9 @@ 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); Should NVIDIA_TEGRA194_SMMU be a separate value for smmu->model, perhaps? That way we avoid this somewhat odd check here. > smmu->impl =3D &arm_mmu500_impl; > break; > case CAVIUM_SMMUV2: > diff --git a/drivers/iommu/arm-smmu-nvidia.c b/drivers/iommu/arm-smmu-nvi= dia.c I wonder if it would be better to name this arm-smmu-tegra.c to make it clearer that this is for a Tegra chip. We do have regular expressions in MAINTAINERS that catch anything with "tegra" in it to make this easier. > new file mode 100644 > index 0000000000000..dafc293a45217 > --- /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 s/Nvidia/NVIDIA/ > +// Copyright (C) 2019 NVIDIA CORPORATION. All rights reserved. I suppose this should now also include 2020. > + > +#define pr_fmt(fmt) "nvidia-smmu: " fmt Same here. Might be worth making this "tegra-smmu: " for consistency. > + > +#include > +#include > +#include > +#include > +#include > + > +#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. "non-isochronous", s/Hw/HW/ > + * Third one is used for SMMU translations from Isochronous HW devices. "isochronous" > + * It is possible to use this Implementation to program either "implementation" > + * all three or two of the instances identically as desired through > + * DT node. > + * > + * Programming all the three instances identically comes with redundant = tlb s/tlb/TLB/ > + * invalidations as all three never need to be tlb invalidated for a HW = device. Same here. > + * > + * When Linux Kernel supports multiple SMMU devices, The SMMU device use= d for "kernel" and "..., the SMMU device" > + * Isochornous HW devices should be added as a separate ARM MMU-500 devi= ce "isochronous" > + * in DT and be programmed independently for efficient tlb invalidates. "TLB" > + * > + */ > +#define MAX_SMMU_INSTANCES 3 > + > +#define TLB_LOOP_TIMEOUT 1000000 /* 1s! */ USEC_PER_SEC? > +#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) Making this static inline can make error messages more readable. > + > +#define nsmmu_page(smmu, inst, page) \ > + (((inst) ? to_nvidia_smmu(smmu)->bases[(inst)] : smmu->base) + \ > + ((page) << smmu->pgshift)) Can we simply define to_nvidia_smmu(smmu)->bases[0] =3D smmu->base in nvidia_smmu_impl_init()? Then this would become just: to_nvidia_smmu(smmu)->bases[inst] + ((page) << (smmu)->pgshift) Also, the nsmmu_ prefix looks somewhat odd here. You already use struct nvidia_smmu as the name of the structure, so why not be consistent and continue to use nvidia_smmu_ as the prefix for function names? Or perhaps even use tegra_smmu_ as the prefix to match the filename change I suggested earlier. > + > +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 =3D 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 =3D 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; I see this is being used to store the value read from a register. I find it clearer to call this "value" or "val" (or in this case perhaps even "status") because whenever I read "reg" I immediately think this is meant to be a register offset, which can then be confusing when I see it used in I/O accessors because it is in the wrong position. But anyway, that's just my opinion and this is a bit subjective, so feel free to ignore. > + unsigned int i; > + unsigned int spin_cnt, delay; > + > + arm_smmu_writel(smmu, page, sync, 0); > + > + for (delay =3D 1; delay < TLB_LOOP_TIMEOUT; delay *=3D 2) { > + for (spin_cnt =3D TLB_SPIN_COUNT; spin_cnt > 0; spin_cnt--) { > + reg =3D 0; You may want to declare the variable at this scope since you never need it outside. Also, use a space between variable initialization and the for block below for better readability. > + for (i =3D 0; i < to_nvidia_smmu(smmu)->num_inst; i++) { > + reg |=3D readl_relaxed( > + nsmmu_page(smmu, i, page) + status); > + } Maybe add a separate variable for the page address so this can be a bit uncluttered. Also, I'd prefer a blank line after the block for readability. > + if (!(reg & ARM_SMMU_sTLBGSTATUS_GSACTIVE)) > + return; > + cpu_relax(); Blank line above cpu_relax() for readability. > + } > + udelay(delay); Again, a blank line between blocks and subsequent statements can help readability. > + } > + dev_err_ratelimited(smmu->dev, > + "TLB sync timed out -- SMMU may be deadlocked\n"); Same here. Also, is there anything we can do when this happens? > +} > + > +static int nsmmu_reset(struct arm_smmu_device *smmu) > +{ > + u32 reg; > + unsigned int i; > + > + for (i =3D 0; i < to_nvidia_smmu(smmu)->num_inst; i++) { > + /* clear global FSR */ > + reg =3D 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 =3D { > + .read_reg =3D nsmmu_read_reg, > + .write_reg =3D nsmmu_write_reg, > + .read_reg64 =3D nsmmu_read_reg64, > + .write_reg64 =3D nsmmu_write_reg64, > + .reset =3D nsmmu_reset, > + .tlb_sync =3D nsmmu_tlb_sync, > +}; > + > +struct arm_smmu_device *nvidia_smmu_impl_init(struct arm_smmu_device *sm= mu) > +{ > + unsigned int i; > + struct nvidia_smmu *nsmmu; > + struct resource *res; > + struct device *dev =3D smmu->dev; > + struct platform_device *pdev =3D to_platform_device(smmu->dev); > + > + nsmmu =3D devm_kzalloc(smmu->dev, sizeof(*nsmmu), GFP_KERNEL); > + if (!nsmmu) > + return ERR_PTR(-ENOMEM); > + > + nsmmu->smmu =3D *smmu; > + /* Instance 0 is ioremapped by arm-smmu.c */ > + nsmmu->num_inst =3D 1; Maybe add this here to simplify the nsmmu_page() macro above: nsmmu->bases[0] =3D smmu->base; > + > + for (i =3D 1; i < MAX_SMMU_INSTANCES; i++) { > + res =3D platform_get_resource(pdev, IORESOURCE_MEM, i); > + if (!res) > + break; > + nsmmu->bases[i] =3D devm_ioremap_resource(dev, res); > + if (IS_ERR(nsmmu->bases[i])) > + return (struct arm_smmu_device *)nsmmu->bases[i]; ERR_CAST()? > + nsmmu->num_inst++; > + } More blank lines would make this much easier to read, in my opinion. > + > + nsmmu->smmu.impl =3D &nvidia_smmu_impl; > + devm_kfree(smmu->dev, smmu); Maybe a comment here would be useful for readers to immediately understand why you're doing this here. > + pr_info("NVIDIA ARM SMMU Implementation, Instances=3D%d\n", > + nsmmu->num_inst); I think I'd just omit this. In general you should only let the user know when things go wrong, but the above is printed when everything goes as expected. 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