of_iommu.c

  1// SPDX-License-Identifier: GPL-2.0-only
  2/*
  3 * OF helpers for IOMMU
  4 *
  5 * Copyright (c) 2012, NVIDIA CORPORATION.  All rights reserved.
  6 */
  7
  8#include <linux/export.h>
  9#include <linux/iommu.h>
 10#include <linux/limits.h>
 11#include <linux/module.h>
 12#include <linux/of.h>
 13#include <linux/of_address.h>
 14#include <linux/of_iommu.h>
 15#include <linux/of_pci.h>
 16#include <linux/pci.h>
 17#include <linux/slab.h>
 18#include <linux/fsl/mc.h>
 19
 20#include "iommu-priv.h"
 21
 22static int of_iommu_xlate(struct device *dev,
 23			  struct of_phandle_args *iommu_spec)
 24{
 25	const struct iommu_ops *ops;
 26	int ret;
 27
 28	if (!of_device_is_available(iommu_spec->np))
 29		return -ENODEV;
 30
 31	ret = iommu_fwspec_init(dev, of_fwnode_handle(iommu_spec->np));
 32	if (ret)
 33		return ret;
 34
 35	ops = iommu_ops_from_fwnode(&iommu_spec->np->fwnode);
 36	if (!ops->of_xlate || !try_module_get(ops->owner))
 37		return -ENODEV;
 38
 39	ret = ops->of_xlate(dev, iommu_spec);
 40	module_put(ops->owner);
 41	return ret;
 42}
 43
 44static int of_iommu_configure_dev_id(struct device_node *master_np,
 45				     struct device *dev,
 46				     const u32 *id)
 47{
 48	struct of_phandle_args iommu_spec = { .args_count = 1 };
 49	int err;
 50
 51	err = of_map_id(master_np, *id, "iommu-map",
 52			 "iommu-map-mask", &iommu_spec.np,
 53			 iommu_spec.args);
 54	if (err)
 55		return err;
 56
 57	err = of_iommu_xlate(dev, &iommu_spec);
 58	of_node_put(iommu_spec.np);
 59	return err;
 60}
 61
 62static int of_iommu_configure_dev(struct device_node *master_np,
 63				  struct device *dev)
 64{
 65	struct of_phandle_args iommu_spec;
 66	int err = -ENODEV, idx = 0;
 67
 68	while (!of_parse_phandle_with_args(master_np, "iommus",
 69					   "#iommu-cells",
 70					   idx, &iommu_spec)) {
 71		err = of_iommu_xlate(dev, &iommu_spec);
 72		of_node_put(iommu_spec.np);
 73		idx++;
 74		if (err)
 75			break;
 76	}
 77
 78	return err;
 79}
 80
 81struct of_pci_iommu_alias_info {
 82	struct device *dev;
 83	struct device_node *np;
 84};
 85
 86static int of_pci_iommu_init(struct pci_dev *pdev, u16 alias, void *data)
 87{
 88	struct of_pci_iommu_alias_info *info = data;
 89	u32 input_id = alias;
 90
 91	return of_iommu_configure_dev_id(info->np, info->dev, &input_id);
 92}
 93
 94static int of_iommu_configure_device(struct device_node *master_np,
 95				     struct device *dev, const u32 *id)
 96{
 97	return (id) ? of_iommu_configure_dev_id(master_np, dev, id) :
 98		      of_iommu_configure_dev(master_np, dev);
 99}
100
101static void of_pci_check_device_ats(struct device *dev, struct device_node *np)
102{
103	struct iommu_fwspec *fwspec = dev_iommu_fwspec_get(dev);
104
105	if (fwspec && of_property_read_bool(np, "ats-supported"))
106		fwspec->flags |= IOMMU_FWSPEC_PCI_RC_ATS;
107}
108
109/*
110 * Returns:
111 *  0 on success, an iommu was configured
112 *  -ENODEV if the device does not have any IOMMU
113 *  -EPROBEDEFER if probing should be tried again
114 *  -errno fatal errors
115 */
116int of_iommu_configure(struct device *dev, struct device_node *master_np,
117		       const u32 *id)
118{
119	bool dev_iommu_present;
120	int err;
121
122	if (!master_np)
123		return -ENODEV;
124
125	/* Serialise to make dev->iommu stable under our potential fwspec */
126	mutex_lock(&iommu_probe_device_lock);
127	if (dev_iommu_fwspec_get(dev)) {
128		mutex_unlock(&iommu_probe_device_lock);
129		return 0;
130	}
131	dev_iommu_present = dev->iommu;
132
133	/*
134	 * We don't currently walk up the tree looking for a parent IOMMU.
135	 * See the `Notes:' section of
136	 * Documentation/devicetree/bindings/iommu/iommu.txt
137	 */
138	if (dev_is_pci(dev)) {
139		struct of_pci_iommu_alias_info info = {
140			.dev = dev,
141			.np = master_np,
142		};
143
144		pci_request_acs();
145		err = pci_for_each_dma_alias(to_pci_dev(dev),
146					     of_pci_iommu_init, &info);
147		of_pci_check_device_ats(dev, master_np);
148	} else {
149		err = of_iommu_configure_device(master_np, dev, id);
150	}
151
152	if (err && dev_iommu_present)
153		iommu_fwspec_free(dev);
154	else if (err && dev->iommu)
155		dev_iommu_free(dev);
156	mutex_unlock(&iommu_probe_device_lock);
157
158	/*
159	 * If we're not on the iommu_probe_device() path (as indicated by the
160	 * initial dev->iommu) then try to simulate it. This should no longer
161	 * happen unless of_dma_configure() is being misused outside bus code.
162	 */
163	if (!err && dev->bus && !dev_iommu_present)
164		err = iommu_probe_device(dev);
165
166	if (err && err != -EPROBE_DEFER)
167		dev_dbg(dev, "Adding to IOMMU failed: %d\n", err);
168
169	return err;
170}
171
172static enum iommu_resv_type __maybe_unused
173iommu_resv_region_get_type(struct device *dev,
174			   struct resource *phys,
175			   phys_addr_t start, size_t length)
176{
177	phys_addr_t end = start + length - 1;
178
179	/*
180	 * IOMMU regions without an associated physical region cannot be
181	 * mapped and are simply reservations.
182	 */
183	if (phys->start >= phys->end)
184		return IOMMU_RESV_RESERVED;
185
186	/* may be IOMMU_RESV_DIRECT_RELAXABLE for certain cases */
187	if (start == phys->start && end == phys->end)
188		return IOMMU_RESV_DIRECT;
189
190	dev_warn(dev, "treating non-direct mapping [%pr] -> [%pap-%pap] as reservation\n", phys,
191		 &start, &end);
192	return IOMMU_RESV_RESERVED;
193}
194
195/**
196 * of_iommu_get_resv_regions - reserved region driver helper for device tree
197 * @dev: device for which to get reserved regions
198 * @list: reserved region list
199 *
200 * IOMMU drivers can use this to implement their .get_resv_regions() callback
201 * for memory regions attached to a device tree node. See the reserved-memory
202 * device tree bindings on how to use these:
203 *
204 *   Documentation/devicetree/bindings/reserved-memory/reserved-memory.txt
205 */
206void of_iommu_get_resv_regions(struct device *dev, struct list_head *list)
207{
208#if IS_ENABLED(CONFIG_OF_ADDRESS)
209	struct of_phandle_iterator it;
210	int err;
211
212	of_for_each_phandle(&it, err, dev->of_node, "memory-region", NULL, 0) {
213		const __be32 *maps, *end;
214		struct resource phys;
215		int size;
216
217		memset(&phys, 0, sizeof(phys));
218
219		/*
220		 * The "reg" property is optional and can be omitted by reserved-memory regions
221		 * that represent reservations in the IOVA space, which are regions that should
222		 * not be mapped.
223		 */
224		if (of_property_present(it.node, "reg")) {
225			err = of_address_to_resource(it.node, 0, &phys);
226			if (err < 0) {
227				dev_err(dev, "failed to parse memory region %pOF: %d\n",
228					it.node, err);
229				continue;
230			}
231		}
232
233		maps = of_get_property(it.node, "iommu-addresses", &size);
234		if (!maps)
235			continue;
236
237		end = maps + size / sizeof(__be32);
238
239		while (maps < end) {
240			struct device_node *np;
241			u32 phandle;
242
243			phandle = be32_to_cpup(maps++);
244			np = of_find_node_by_phandle(phandle);
245
246			if (np == dev->of_node) {
247				int prot = IOMMU_READ | IOMMU_WRITE;
248				struct iommu_resv_region *region;
249				enum iommu_resv_type type;
250				phys_addr_t iova;
251				size_t length;
252
253				if (of_dma_is_coherent(dev->of_node))
254					prot |= IOMMU_CACHE;
255
256				maps = of_translate_dma_region(np, maps, &iova, &length);
257				if (length == 0) {
258					dev_warn(dev, "Cannot reserve IOVA region of 0 size\n");
259					continue;
260				}
261				type = iommu_resv_region_get_type(dev, &phys, iova, length);
262
263				region = iommu_alloc_resv_region(iova, length, prot, type,
264								 GFP_KERNEL);
265				if (region)
266					list_add_tail(&region->list, list);
267			}
268		}
269	}
270#endif
271}
272EXPORT_SYMBOL(of_iommu_get_resv_regions);