From 25938c73cd7918169f80196e288fc3abb81053e5 Mon Sep 17 00:00:00 2001 From: Nicolin Chen Date: Wed, 25 Nov 2020 02:10:12 -0800 Subject: [PATCH] iommu/tegra-smmu: Rework tegra_smmu_probe_device() The bus_set_iommu() in tegra_smmu_probe() enumerates all clients to call in tegra_smmu_probe_device() where each client searches its DT node for smmu pointer and swgroup ID, so as to configure an fwspec. But this requires a valid smmu pointer even before mc and smmu drivers are probed. So in tegra_smmu_probe() we added a line of code to fill mc->smmu, marking "a bit of a hack". This works for most of clients in the DTB, however, doesn't work for a client that doesn't exist in DTB, a PCI device for example. Actually, if we return ERR_PTR(-ENODEV) in ->probe_device() when it's called from bus_set_iommu(), iommu core will let everything carry on. Then when a client gets probed, of_iommu_configure() in iommu core will search DTB for swgroup ID and call ->of_xlate() to prepare an fwspec, similar to tegra_smmu_probe_device() and tegra_smmu_configure(). Then it'll call tegra_smmu_probe_device() again, and this time we shall return smmu->iommu pointer properly. So we can get rid of tegra_smmu_find() and tegra_smmu_configure() along with DT polling code by letting the iommu core handle every thing, except a problem that we search iommus property in DTB not only for swgroup ID but also for mc node to get mc->smmu pointer to call dev_iommu_priv_set() and return the smmu->iommu pointer. So we'll need to find another way to get smmu pointer. Referencing the implementation of sun50i-iommu driver, of_xlate() has client's dev pointer, mc node and swgroup ID. This means that we can call dev_iommu_priv_set() in of_xlate() instead, so we can simply get smmu pointer in ->probe_device(). This patch reworks tegra_smmu_probe_device() by: 1) Removing mc->smmu hack in tegra_smmu_probe() so as to return ERR_PTR(-ENODEV) in tegra_smmu_probe_device() during stage of tegra_smmu_probe/tegra_mc_probe(). 2) Moving dev_iommu_priv_set() to of_xlate() so we can get smmu pointer in tegra_smmu_probe_device() to replace DTB polling. 3) Removing tegra_smmu_configure() accordingly since iommu core takes care of it. This also fixes a problem that previously we could add clients to iommu groups before iommu core initializes its default domain: ubuntu@jetson:~$ dmesg | grep iommu platform 50000000.host1x: Adding to iommu group 1 platform 57000000.gpu: Adding to iommu group 2 iommu: Default domain type: Translated platform 54200000.dc: Adding to iommu group 3 platform 54240000.dc: Adding to iommu group 3 platform 54340000.vic: Adding to iommu group 4 Though it works fine with IOMMU_DOMAIN_UNMANAGED, but will have warnings if switching to IOMMU_DOMAIN_DMA: iommu: Failed to allocate default IOMMU domain of type 0 for group (null) - Falling back to IOMMU_DOMAIN_DMA iommu: Failed to allocate default IOMMU domain of type 0 for group (null) - Falling back to IOMMU_DOMAIN_DMA Now, bypassing the first probe_device() call from bus_set_iommu() fixes the sequence: ubuntu@jetson:~$ dmesg | grep iommu iommu: Default domain type: Translated tegra-host1x 50000000.host1x: Adding to iommu group 0 tegra-dc 54200000.dc: Adding to iommu group 1 tegra-dc 54240000.dc: Adding to iommu group 1 tegra-vic 54340000.vic: Adding to iommu group 2 nouveau 57000000.gpu: Adding to iommu group 3 Note that dmesg log above is testing with IOMMU_DOMAIN_UNMANAGED. Signed-off-by: Nicolin Chen Tested-by: Dmitry Osipenko Reviewed-by: Dmitry Osipenko Acked-by: Thierry Reding Link: https://lore.kernel.org/r/20201125101013.14953-5-nicoleotsuka@gmail.com Signed-off-by: Will Deacon --- drivers/iommu/tegra-smmu.c | 96 ++++++-------------------------------- 1 file changed, 15 insertions(+), 81 deletions(-) diff --git a/drivers/iommu/tegra-smmu.c b/drivers/iommu/tegra-smmu.c index 297d49f3f80e..f45ed43cf8db 100644 --- a/drivers/iommu/tegra-smmu.c +++ b/drivers/iommu/tegra-smmu.c @@ -797,75 +797,9 @@ static phys_addr_t tegra_smmu_iova_to_phys(struct iommu_domain *domain, return SMMU_PFN_PHYS(pfn) + SMMU_OFFSET_IN_PAGE(iova); } -static struct tegra_smmu *tegra_smmu_find(struct device_node *np) -{ - struct platform_device *pdev; - struct tegra_mc *mc; - - pdev = of_find_device_by_node(np); - if (!pdev) - return NULL; - - mc = platform_get_drvdata(pdev); - if (!mc) - return NULL; - - return mc->smmu; -} - -static int tegra_smmu_configure(struct tegra_smmu *smmu, struct device *dev, - struct of_phandle_args *args) -{ - const struct iommu_ops *ops = smmu->iommu.ops; - int err; - - err = iommu_fwspec_init(dev, &dev->of_node->fwnode, ops); - if (err < 0) { - dev_err(dev, "failed to initialize fwspec: %d\n", err); - return err; - } - - err = ops->of_xlate(dev, args); - if (err < 0) { - dev_err(dev, "failed to parse SW group ID: %d\n", err); - iommu_fwspec_free(dev); - return err; - } - - return 0; -} - static struct iommu_device *tegra_smmu_probe_device(struct device *dev) { - struct device_node *np = dev->of_node; - struct tegra_smmu *smmu = NULL; - struct of_phandle_args args; - unsigned int index = 0; - int err; - - while (of_parse_phandle_with_args(np, "iommus", "#iommu-cells", index, - &args) == 0) { - smmu = tegra_smmu_find(args.np); - if (smmu) { - err = tegra_smmu_configure(smmu, dev, &args); - of_node_put(args.np); - - if (err < 0) - return ERR_PTR(err); - - /* - * Only a single IOMMU master interface is currently - * supported by the Linux kernel, so abort after the - * first match. - */ - dev_iommu_priv_set(dev, smmu); - - break; - } - - of_node_put(args.np); - index++; - } + struct tegra_smmu *smmu = dev_iommu_priv_get(dev); if (!smmu) return ERR_PTR(-ENODEV); @@ -873,10 +807,7 @@ static struct iommu_device *tegra_smmu_probe_device(struct device *dev) return &smmu->iommu; } -static void tegra_smmu_release_device(struct device *dev) -{ - dev_iommu_priv_set(dev, NULL); -} +static void tegra_smmu_release_device(struct device *dev) {} static const struct tegra_smmu_group_soc * tegra_smmu_find_group(struct tegra_smmu *smmu, unsigned int swgroup) @@ -953,8 +884,21 @@ static struct iommu_group *tegra_smmu_device_group(struct device *dev) static int tegra_smmu_of_xlate(struct device *dev, struct of_phandle_args *args) { + struct platform_device *iommu_pdev = of_find_device_by_node(args->np); + struct tegra_mc *mc = platform_get_drvdata(iommu_pdev); u32 id = args->args[0]; + /* + * Note: we are here releasing the reference of &iommu_pdev->dev, which + * is mc->dev. Although some functions in tegra_smmu_ops may keep using + * its private data beyond this point, it's still safe to do so because + * the SMMU parent device is the same as the MC, so the reference count + * isn't strictly necessary. + */ + put_device(&iommu_pdev->dev); + + dev_iommu_priv_set(dev, mc->smmu); + return iommu_fwspec_add_ids(dev, &id, 1); } @@ -1079,16 +1023,6 @@ struct tegra_smmu *tegra_smmu_probe(struct device *dev, if (!smmu) return ERR_PTR(-ENOMEM); - /* - * This is a bit of a hack. Ideally we'd want to simply return this - * value. However the IOMMU registration process will attempt to add - * all devices to the IOMMU when bus_set_iommu() is called. In order - * not to rely on global variables to track the IOMMU instance, we - * set it here so that it can be looked up from the .probe_device() - * callback via the IOMMU device's .drvdata field. - */ - mc->smmu = smmu; - size = BITS_TO_LONGS(soc->num_asids) * sizeof(long); smmu->asids = devm_kzalloc(dev, size, GFP_KERNEL);