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![Laurent Pinchart](/assets/img/avatar_default.png)
Failures to look up an IOMMU when parsing the DT iommus property need to be handled separately from the .of_xlate() failures to support deferred probing. The lack of a registered IOMMU can be caused by the lack of a driver for the IOMMU, the IOMMU device probe not having been performed yet, having been deferred, or having failed. The first case occurs when the device tree describes the bus master and IOMMU topology correctly but no device driver exists for the IOMMU yet or the device driver has not been compiled in. Return NULL, the caller will configure the device without an IOMMU. The second and third cases are handled by deferring the probe of the bus master device which will eventually get reprobed after the IOMMU. The last case is currently handled by deferring the probe of the bus master device as well. A mechanism to either configure the bus master device without an IOMMU or to fail the bus master device probe depending on whether the IOMMU is optional or mandatory would be a good enhancement. Tested-by: Marek Szyprowski <m.szyprowski@samsung.com> Reviewed-by: Robin Murphy <robin.murphy@arm.com> Acked-by: Rob Herring <robh@kernel.org> Signed-off-by: Laurent Pichart <laurent.pinchart+renesas@ideasonboard.com> Signed-off-by: Sricharan R <sricharan@codeaurora.org> Signed-off-by: Joerg Roedel <jroedel@suse.de>
257 lines
6.9 KiB
C
257 lines
6.9 KiB
C
/*
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* OF helpers for IOMMU
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*
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* Copyright (c) 2012, NVIDIA CORPORATION. All rights reserved.
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*
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* This program is free software; you can redistribute it and/or modify it
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* under the terms and conditions of the GNU General Public License,
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* version 2, as published by the Free Software Foundation.
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*
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* This program is distributed in the hope it will be useful, but WITHOUT
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* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
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* more details.
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*
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* You should have received a copy of the GNU General Public License along with
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* this program; if not, write to the Free Software Foundation, Inc.,
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* 51 Franklin St - Fifth Floor, Boston, MA 02110-1301 USA.
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*/
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#include <linux/export.h>
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#include <linux/iommu.h>
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#include <linux/limits.h>
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#include <linux/of.h>
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#include <linux/of_iommu.h>
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#include <linux/of_pci.h>
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#include <linux/slab.h>
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static const struct of_device_id __iommu_of_table_sentinel
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__used __section(__iommu_of_table_end);
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/**
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* of_get_dma_window - Parse *dma-window property and returns 0 if found.
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*
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* @dn: device node
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* @prefix: prefix for property name if any
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* @index: index to start to parse
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* @busno: Returns busno if supported. Otherwise pass NULL
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* @addr: Returns address that DMA starts
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* @size: Returns the range that DMA can handle
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*
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* This supports different formats flexibly. "prefix" can be
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* configured if any. "busno" and "index" are optionally
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* specified. Set 0(or NULL) if not used.
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*/
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int of_get_dma_window(struct device_node *dn, const char *prefix, int index,
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unsigned long *busno, dma_addr_t *addr, size_t *size)
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{
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const __be32 *dma_window, *end;
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int bytes, cur_index = 0;
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char propname[NAME_MAX], addrname[NAME_MAX], sizename[NAME_MAX];
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if (!dn || !addr || !size)
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return -EINVAL;
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if (!prefix)
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prefix = "";
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snprintf(propname, sizeof(propname), "%sdma-window", prefix);
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snprintf(addrname, sizeof(addrname), "%s#dma-address-cells", prefix);
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snprintf(sizename, sizeof(sizename), "%s#dma-size-cells", prefix);
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dma_window = of_get_property(dn, propname, &bytes);
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if (!dma_window)
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return -ENODEV;
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end = dma_window + bytes / sizeof(*dma_window);
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while (dma_window < end) {
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u32 cells;
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const void *prop;
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/* busno is one cell if supported */
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if (busno)
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*busno = be32_to_cpup(dma_window++);
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prop = of_get_property(dn, addrname, NULL);
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if (!prop)
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prop = of_get_property(dn, "#address-cells", NULL);
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cells = prop ? be32_to_cpup(prop) : of_n_addr_cells(dn);
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if (!cells)
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return -EINVAL;
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*addr = of_read_number(dma_window, cells);
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dma_window += cells;
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prop = of_get_property(dn, sizename, NULL);
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cells = prop ? be32_to_cpup(prop) : of_n_size_cells(dn);
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if (!cells)
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return -EINVAL;
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*size = of_read_number(dma_window, cells);
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dma_window += cells;
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if (cur_index++ == index)
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break;
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}
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return 0;
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}
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EXPORT_SYMBOL_GPL(of_get_dma_window);
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static bool of_iommu_driver_present(struct device_node *np)
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{
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/*
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* If the IOMMU still isn't ready by the time we reach init, assume
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* it never will be. We don't want to defer indefinitely, nor attempt
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* to dereference __iommu_of_table after it's been freed.
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*/
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if (system_state > SYSTEM_BOOTING)
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return false;
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return of_match_node(&__iommu_of_table, np);
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}
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static const struct iommu_ops
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*of_iommu_xlate(struct device *dev, struct of_phandle_args *iommu_spec)
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{
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const struct iommu_ops *ops;
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struct fwnode_handle *fwnode = &iommu_spec->np->fwnode;
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int err;
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ops = iommu_ops_from_fwnode(fwnode);
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if ((ops && !ops->of_xlate) ||
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(!ops && !of_iommu_driver_present(iommu_spec->np)))
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return NULL;
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err = iommu_fwspec_init(dev, &iommu_spec->np->fwnode, ops);
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if (err)
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return ERR_PTR(err);
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/*
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* The otherwise-empty fwspec handily serves to indicate the specific
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* IOMMU device we're waiting for, which will be useful if we ever get
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* a proper probe-ordering dependency mechanism in future.
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*/
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if (!ops)
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return ERR_PTR(-EPROBE_DEFER);
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err = ops->of_xlate(dev, iommu_spec);
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if (err)
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return ERR_PTR(err);
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return ops;
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}
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static int __get_pci_rid(struct pci_dev *pdev, u16 alias, void *data)
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{
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struct of_phandle_args *iommu_spec = data;
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iommu_spec->args[0] = alias;
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return iommu_spec->np == pdev->bus->dev.of_node;
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}
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static const struct iommu_ops
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*of_pci_iommu_init(struct pci_dev *pdev, struct device_node *bridge_np)
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{
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const struct iommu_ops *ops;
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struct of_phandle_args iommu_spec;
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int err;
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/*
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* Start by tracing the RID alias down the PCI topology as
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* far as the host bridge whose OF node we have...
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* (we're not even attempting to handle multi-alias devices yet)
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*/
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iommu_spec.args_count = 1;
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iommu_spec.np = bridge_np;
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pci_for_each_dma_alias(pdev, __get_pci_rid, &iommu_spec);
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/*
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* ...then find out what that becomes once it escapes the PCI
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* bus into the system beyond, and which IOMMU it ends up at.
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*/
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iommu_spec.np = NULL;
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err = of_pci_map_rid(bridge_np, iommu_spec.args[0], "iommu-map",
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"iommu-map-mask", &iommu_spec.np,
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iommu_spec.args);
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if (err)
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return err == -ENODEV ? NULL : ERR_PTR(err);
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ops = of_iommu_xlate(&pdev->dev, &iommu_spec);
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of_node_put(iommu_spec.np);
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return ops;
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}
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static const struct iommu_ops
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*of_platform_iommu_init(struct device *dev, struct device_node *np)
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{
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struct of_phandle_args iommu_spec;
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const struct iommu_ops *ops = NULL;
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int idx = 0;
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/*
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* We don't currently walk up the tree looking for a parent IOMMU.
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* See the `Notes:' section of
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* Documentation/devicetree/bindings/iommu/iommu.txt
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*/
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while (!of_parse_phandle_with_args(np, "iommus", "#iommu-cells",
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idx, &iommu_spec)) {
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ops = of_iommu_xlate(dev, &iommu_spec);
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of_node_put(iommu_spec.np);
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idx++;
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if (IS_ERR_OR_NULL(ops))
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break;
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}
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return ops;
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}
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const struct iommu_ops *of_iommu_configure(struct device *dev,
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struct device_node *master_np)
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{
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const struct iommu_ops *ops;
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struct iommu_fwspec *fwspec = dev->iommu_fwspec;
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if (!master_np)
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return NULL;
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if (fwspec) {
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if (fwspec->ops)
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return fwspec->ops;
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/* In the deferred case, start again from scratch */
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iommu_fwspec_free(dev);
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}
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if (dev_is_pci(dev))
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ops = of_pci_iommu_init(to_pci_dev(dev), master_np);
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else
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ops = of_platform_iommu_init(dev, master_np);
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/*
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* If we have reason to believe the IOMMU driver missed the initial
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* add_device callback for dev, replay it to get things in order.
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*/
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if (!IS_ERR_OR_NULL(ops) && ops->add_device &&
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dev->bus && !dev->iommu_group) {
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int err = ops->add_device(dev);
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if (err)
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ops = ERR_PTR(err);
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}
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return ops;
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}
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static int __init of_iommu_init(void)
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{
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struct device_node *np;
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const struct of_device_id *match, *matches = &__iommu_of_table;
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for_each_matching_node_and_match(np, matches, &match) {
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const of_iommu_init_fn init_fn = match->data;
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if (init_fn && init_fn(np))
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pr_err("Failed to initialise IOMMU %s\n",
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of_node_full_name(np));
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}
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return 0;
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}
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postcore_initcall_sync(of_iommu_init);
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