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 
of_iommu_xlate(struct device * dev,struct of_phandle_args * iommu_spec)22 static int of_iommu_xlate(struct device *dev,
23 			  struct of_phandle_args *iommu_spec)
24 {
25 	const struct iommu_ops *ops;
26 	struct fwnode_handle *fwnode = &iommu_spec->np->fwnode;
27 	int ret;
28 
29 	ops = iommu_ops_from_fwnode(fwnode);
30 	if ((ops && !ops->of_xlate) ||
31 	    !of_device_is_available(iommu_spec->np))
32 		return NO_IOMMU;
33 
34 	ret = iommu_fwspec_init(dev, &iommu_spec->np->fwnode, ops);
35 	if (ret)
36 		return ret;
37 	/*
38 	 * The otherwise-empty fwspec handily serves to indicate the specific
39 	 * IOMMU device we're waiting for, which will be useful if we ever get
40 	 * a proper probe-ordering dependency mechanism in future.
41 	 */
42 	if (!ops)
43 		return driver_deferred_probe_check_state(dev);
44 
45 	if (!try_module_get(ops->owner))
46 		return -ENODEV;
47 
48 	ret = ops->of_xlate(dev, iommu_spec);
49 	module_put(ops->owner);
50 	return ret;
51 }
52 
of_iommu_configure_dev_id(struct device_node * master_np,struct device * dev,const u32 * id)53 static int of_iommu_configure_dev_id(struct device_node *master_np,
54 				     struct device *dev,
55 				     const u32 *id)
56 {
57 	struct of_phandle_args iommu_spec = { .args_count = 1 };
58 	int err;
59 
60 	err = of_map_id(master_np, *id, "iommu-map",
61 			 "iommu-map-mask", &iommu_spec.np,
62 			 iommu_spec.args);
63 	if (err)
64 		return err == -ENODEV ? NO_IOMMU : err;
65 
66 	err = of_iommu_xlate(dev, &iommu_spec);
67 	of_node_put(iommu_spec.np);
68 	return err;
69 }
70 
of_iommu_configure_dev(struct device_node * master_np,struct device * dev)71 static int of_iommu_configure_dev(struct device_node *master_np,
72 				  struct device *dev)
73 {
74 	struct of_phandle_args iommu_spec;
75 	int err = NO_IOMMU, idx = 0;
76 
77 	while (!of_parse_phandle_with_args(master_np, "iommus",
78 					   "#iommu-cells",
79 					   idx, &iommu_spec)) {
80 		err = of_iommu_xlate(dev, &iommu_spec);
81 		of_node_put(iommu_spec.np);
82 		idx++;
83 		if (err)
84 			break;
85 	}
86 
87 	return err;
88 }
89 
90 struct of_pci_iommu_alias_info {
91 	struct device *dev;
92 	struct device_node *np;
93 };
94 
of_pci_iommu_init(struct pci_dev * pdev,u16 alias,void * data)95 static int of_pci_iommu_init(struct pci_dev *pdev, u16 alias, void *data)
96 {
97 	struct of_pci_iommu_alias_info *info = data;
98 	u32 input_id = alias;
99 
100 	return of_iommu_configure_dev_id(info->np, info->dev, &input_id);
101 }
102 
of_iommu_configure_device(struct device_node * master_np,struct device * dev,const u32 * id)103 static int of_iommu_configure_device(struct device_node *master_np,
104 				     struct device *dev, const u32 *id)
105 {
106 	return (id) ? of_iommu_configure_dev_id(master_np, dev, id) :
107 		      of_iommu_configure_dev(master_np, dev);
108 }
109 
of_iommu_configure(struct device * dev,struct device_node * master_np,const u32 * id)110 const struct iommu_ops *of_iommu_configure(struct device *dev,
111 					   struct device_node *master_np,
112 					   const u32 *id)
113 {
114 	const struct iommu_ops *ops = NULL;
115 	struct iommu_fwspec *fwspec = dev_iommu_fwspec_get(dev);
116 	int err = NO_IOMMU;
117 
118 	if (!master_np)
119 		return NULL;
120 
121 	if (fwspec) {
122 		if (fwspec->ops)
123 			return fwspec->ops;
124 
125 		/* In the deferred case, start again from scratch */
126 		iommu_fwspec_free(dev);
127 	}
128 
129 	/*
130 	 * We don't currently walk up the tree looking for a parent IOMMU.
131 	 * See the `Notes:' section of
132 	 * Documentation/devicetree/bindings/iommu/iommu.txt
133 	 */
134 	if (dev_is_pci(dev)) {
135 		struct of_pci_iommu_alias_info info = {
136 			.dev = dev,
137 			.np = master_np,
138 		};
139 
140 		pci_request_acs();
141 		err = pci_for_each_dma_alias(to_pci_dev(dev),
142 					     of_pci_iommu_init, &info);
143 	} else {
144 		err = of_iommu_configure_device(master_np, dev, id);
145 	}
146 
147 	/*
148 	 * Two success conditions can be represented by non-negative err here:
149 	 * >0 : there is no IOMMU, or one was unavailable for non-fatal reasons
150 	 *  0 : we found an IOMMU, and dev->fwspec is initialised appropriately
151 	 * <0 : any actual error
152 	 */
153 	if (!err) {
154 		/* The fwspec pointer changed, read it again */
155 		fwspec = dev_iommu_fwspec_get(dev);
156 		ops    = fwspec->ops;
157 	}
158 	/*
159 	 * If we have reason to believe the IOMMU driver missed the initial
160 	 * probe for dev, replay it to get things in order.
161 	 */
162 	if (!err && dev->bus && !device_iommu_mapped(dev))
163 		err = iommu_probe_device(dev);
164 
165 	/* Ignore all other errors apart from EPROBE_DEFER */
166 	if (err == -EPROBE_DEFER) {
167 		ops = ERR_PTR(err);
168 	} else if (err < 0) {
169 		dev_dbg(dev, "Adding to IOMMU failed: %d\n", err);
170 		ops = NULL;
171 	}
172 
173 	return ops;
174 }
175