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/msi.h>
 13#include <linux/of.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#define NO_IOMMU	1
 21
 22/**
 23 * of_get_dma_window - Parse *dma-window property and returns 0 if found.
 24 *
 25 * @dn: device node
 26 * @prefix: prefix for property name if any
 27 * @index: index to start to parse
 28 * @busno: Returns busno if supported. Otherwise pass NULL
 29 * @addr: Returns address that DMA starts
 30 * @size: Returns the range that DMA can handle
 31 *
 32 * This supports different formats flexibly. "prefix" can be
 33 * configured if any. "busno" and "index" are optionally
 34 * specified. Set 0(or NULL) if not used.
 35 */
 36int of_get_dma_window(struct device_node *dn, const char *prefix, int index,
 37		      unsigned long *busno, dma_addr_t *addr, size_t *size)
 38{
 39	const __be32 *dma_window, *end;
 40	int bytes, cur_index = 0;
 41	char propname[NAME_MAX], addrname[NAME_MAX], sizename[NAME_MAX];
 42
 43	if (!dn || !addr || !size)
 44		return -EINVAL;
 45
 46	if (!prefix)
 47		prefix = "";
 48
 49	snprintf(propname, sizeof(propname), "%sdma-window", prefix);
 50	snprintf(addrname, sizeof(addrname), "%s#dma-address-cells", prefix);
 51	snprintf(sizename, sizeof(sizename), "%s#dma-size-cells", prefix);
 52
 53	dma_window = of_get_property(dn, propname, &bytes);
 54	if (!dma_window)
 55		return -ENODEV;
 56	end = dma_window + bytes / sizeof(*dma_window);
 57
 58	while (dma_window < end) {
 59		u32 cells;
 60		const void *prop;
 61
 62		/* busno is one cell if supported */
 63		if (busno)
 64			*busno = be32_to_cpup(dma_window++);
 65
 66		prop = of_get_property(dn, addrname, NULL);
 67		if (!prop)
 68			prop = of_get_property(dn, "#address-cells", NULL);
 69
 70		cells = prop ? be32_to_cpup(prop) : of_n_addr_cells(dn);
 71		if (!cells)
 72			return -EINVAL;
 73		*addr = of_read_number(dma_window, cells);
 74		dma_window += cells;
 75
 76		prop = of_get_property(dn, sizename, NULL);
 77		cells = prop ? be32_to_cpup(prop) : of_n_size_cells(dn);
 78		if (!cells)
 79			return -EINVAL;
 80		*size = of_read_number(dma_window, cells);
 81		dma_window += cells;
 82
 83		if (cur_index++ == index)
 84			break;
 85	}
 86	return 0;
 87}
 88EXPORT_SYMBOL_GPL(of_get_dma_window);
 89
 90static int of_iommu_xlate(struct device *dev,
 91			  struct of_phandle_args *iommu_spec)
 92{
 93	const struct iommu_ops *ops;
 94	struct fwnode_handle *fwnode = &iommu_spec->np->fwnode;
 95	int ret;
 96
 97	ops = iommu_ops_from_fwnode(fwnode);
 98	if ((ops && !ops->of_xlate) ||
 99	    !of_device_is_available(iommu_spec->np))
100		return NO_IOMMU;
101
102	ret = iommu_fwspec_init(dev, &iommu_spec->np->fwnode, ops);
103	if (ret)
104		return ret;
105	/*
106	 * The otherwise-empty fwspec handily serves to indicate the specific
107	 * IOMMU device we're waiting for, which will be useful if we ever get
108	 * a proper probe-ordering dependency mechanism in future.
109	 */
110	if (!ops)
111		return driver_deferred_probe_check_state(dev);
112
113	if (!try_module_get(ops->owner))
114		return -ENODEV;
115
116	ret = ops->of_xlate(dev, iommu_spec);
117	module_put(ops->owner);
118	return ret;
119}
120
121static int of_iommu_configure_dev_id(struct device_node *master_np,
122				     struct device *dev,
123				     const u32 *id)
124{
125	struct of_phandle_args iommu_spec = { .args_count = 1 };
126	int err;
127
128	err = of_map_id(master_np, *id, "iommu-map",
129			 "iommu-map-mask", &iommu_spec.np,
130			 iommu_spec.args);
131	if (err)
132		return err == -ENODEV ? NO_IOMMU : err;
133
134	err = of_iommu_xlate(dev, &iommu_spec);
135	of_node_put(iommu_spec.np);
136	return err;
137}
138
139static int of_iommu_configure_dev(struct device_node *master_np,
140				  struct device *dev)
141{
142	struct of_phandle_args iommu_spec;
143	int err = NO_IOMMU, idx = 0;
144
145	while (!of_parse_phandle_with_args(master_np, "iommus",
146					   "#iommu-cells",
147					   idx, &iommu_spec)) {
148		err = of_iommu_xlate(dev, &iommu_spec);
149		of_node_put(iommu_spec.np);
150		idx++;
151		if (err)
152			break;
153	}
154
155	return err;
156}
157
158struct of_pci_iommu_alias_info {
159	struct device *dev;
160	struct device_node *np;
161};
162
163static int of_pci_iommu_init(struct pci_dev *pdev, u16 alias, void *data)
164{
165	struct of_pci_iommu_alias_info *info = data;
166	u32 input_id = alias;
167
168	return of_iommu_configure_dev_id(info->np, info->dev, &input_id);
169}
170
171static int of_iommu_configure_device(struct device_node *master_np,
172				     struct device *dev, const u32 *id)
173{
174	return (id) ? of_iommu_configure_dev_id(master_np, dev, id) :
175		      of_iommu_configure_dev(master_np, dev);
176}
177
178const struct iommu_ops *of_iommu_configure(struct device *dev,
179					   struct device_node *master_np,
180					   const u32 *id)
181{
182	const struct iommu_ops *ops = NULL;
183	struct iommu_fwspec *fwspec = dev_iommu_fwspec_get(dev);
184	int err = NO_IOMMU;
185
186	if (!master_np)
187		return NULL;
188
189	if (fwspec) {
190		if (fwspec->ops)
191			return fwspec->ops;
192
193		/* In the deferred case, start again from scratch */
194		iommu_fwspec_free(dev);
195	}
196
197	/*
198	 * We don't currently walk up the tree looking for a parent IOMMU.
199	 * See the `Notes:' section of
200	 * Documentation/devicetree/bindings/iommu/iommu.txt
201	 */
202	if (dev_is_pci(dev)) {
203		struct of_pci_iommu_alias_info info = {
204			.dev = dev,
205			.np = master_np,
206		};
207
208		pci_request_acs();
209		err = pci_for_each_dma_alias(to_pci_dev(dev),
210					     of_pci_iommu_init, &info);
211	} else {
212		err = of_iommu_configure_device(master_np, dev, id);
213
214		fwspec = dev_iommu_fwspec_get(dev);
215		if (!err && fwspec)
216			of_property_read_u32(master_np, "pasid-num-bits",
217					     &fwspec->num_pasid_bits);
218	}
219
220	/*
221	 * Two success conditions can be represented by non-negative err here:
222	 * >0 : there is no IOMMU, or one was unavailable for non-fatal reasons
223	 *  0 : we found an IOMMU, and dev->fwspec is initialised appropriately
224	 * <0 : any actual error
225	 */
226	if (!err) {
227		/* The fwspec pointer changed, read it again */
228		fwspec = dev_iommu_fwspec_get(dev);
229		ops    = fwspec->ops;
230	}
231	/*
232	 * If we have reason to believe the IOMMU driver missed the initial
233	 * probe for dev, replay it to get things in order.
234	 */
235	if (!err && dev->bus && !device_iommu_mapped(dev))
236		err = iommu_probe_device(dev);
237
238	/* Ignore all other errors apart from EPROBE_DEFER */
239	if (err == -EPROBE_DEFER) {
240		ops = ERR_PTR(err);
241	} else if (err < 0) {
242		dev_dbg(dev, "Adding to IOMMU failed: %d\n", err);
243		ops = NULL;
244	}
245
246	return ops;
247}