xref: /openbmc/linux/drivers/pci/ecam.c (revision 2d96b44f)
1 /*
2  * Copyright 2016 Broadcom
3  *
4  * This program is free software; you can redistribute it and/or modify
5  * it under the terms of the GNU General Public License, version 2, as
6  * published by the Free Software Foundation (the "GPL").
7  *
8  * This program is distributed in the hope that it will be useful, but
9  * WITHOUT ANY WARRANTY; without even the implied warranty of
10  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
11  * General Public License version 2 (GPLv2) for more details.
12  *
13  * You should have received a copy of the GNU General Public License
14  * version 2 (GPLv2) along with this source code.
15  */
16 
17 #include <linux/device.h>
18 #include <linux/io.h>
19 #include <linux/kernel.h>
20 #include <linux/module.h>
21 #include <linux/pci.h>
22 #include <linux/pci-ecam.h>
23 #include <linux/slab.h>
24 
25 /*
26  * On 64-bit systems, we do a single ioremap for the whole config space
27  * since we have enough virtual address range available.  On 32-bit, we
28  * ioremap the config space for each bus individually.
29  */
30 static const bool per_bus_mapping = !IS_ENABLED(CONFIG_64BIT);
31 
32 /*
33  * Create a PCI config space window
34  *  - reserve mem region
35  *  - alloc struct pci_config_window with space for all mappings
36  *  - ioremap the config space
37  */
38 struct pci_config_window *pci_ecam_create(struct device *dev,
39 		struct resource *cfgres, struct resource *busr,
40 		struct pci_ecam_ops *ops)
41 {
42 	struct pci_config_window *cfg;
43 	unsigned int bus_range, bus_range_max, bsz;
44 	struct resource *conflict;
45 	int i, err;
46 
47 	if (busr->start > busr->end)
48 		return ERR_PTR(-EINVAL);
49 
50 	cfg = kzalloc(sizeof(*cfg), GFP_KERNEL);
51 	if (!cfg)
52 		return ERR_PTR(-ENOMEM);
53 
54 	cfg->parent = dev;
55 	cfg->ops = ops;
56 	cfg->busr.start = busr->start;
57 	cfg->busr.end = busr->end;
58 	cfg->busr.flags = IORESOURCE_BUS;
59 	bus_range = resource_size(&cfg->busr);
60 	bus_range_max = resource_size(cfgres) >> ops->bus_shift;
61 	if (bus_range > bus_range_max) {
62 		bus_range = bus_range_max;
63 		cfg->busr.end = busr->start + bus_range - 1;
64 		dev_warn(dev, "ECAM area %pR can only accommodate %pR (reduced from %pR desired)\n",
65 			 cfgres, &cfg->busr, busr);
66 	}
67 	bsz = 1 << ops->bus_shift;
68 
69 	cfg->res.start = cfgres->start;
70 	cfg->res.end = cfgres->end;
71 	cfg->res.flags = IORESOURCE_MEM | IORESOURCE_BUSY;
72 	cfg->res.name = "PCI ECAM";
73 
74 	conflict = request_resource_conflict(&iomem_resource, &cfg->res);
75 	if (conflict) {
76 		err = -EBUSY;
77 		dev_err(dev, "can't claim ECAM area %pR: address conflict with %s %pR\n",
78 			&cfg->res, conflict->name, conflict);
79 		goto err_exit;
80 	}
81 
82 	if (per_bus_mapping) {
83 		cfg->winp = kcalloc(bus_range, sizeof(*cfg->winp), GFP_KERNEL);
84 		if (!cfg->winp)
85 			goto err_exit_malloc;
86 		for (i = 0; i < bus_range; i++) {
87 			cfg->winp[i] = ioremap(cfgres->start + i * bsz, bsz);
88 			if (!cfg->winp[i])
89 				goto err_exit_iomap;
90 		}
91 	} else {
92 		cfg->win = ioremap(cfgres->start, bus_range * bsz);
93 		if (!cfg->win)
94 			goto err_exit_iomap;
95 	}
96 
97 	if (ops->init) {
98 		err = ops->init(cfg);
99 		if (err)
100 			goto err_exit;
101 	}
102 	dev_info(dev, "ECAM at %pR for %pR\n", &cfg->res, &cfg->busr);
103 	return cfg;
104 
105 err_exit_iomap:
106 	dev_err(dev, "ECAM ioremap failed\n");
107 err_exit_malloc:
108 	err = -ENOMEM;
109 err_exit:
110 	pci_ecam_free(cfg);
111 	return ERR_PTR(err);
112 }
113 
114 void pci_ecam_free(struct pci_config_window *cfg)
115 {
116 	int i;
117 
118 	if (per_bus_mapping) {
119 		if (cfg->winp) {
120 			for (i = 0; i < resource_size(&cfg->busr); i++)
121 				if (cfg->winp[i])
122 					iounmap(cfg->winp[i]);
123 			kfree(cfg->winp);
124 		}
125 	} else {
126 		if (cfg->win)
127 			iounmap(cfg->win);
128 	}
129 	if (cfg->res.parent)
130 		release_resource(&cfg->res);
131 	kfree(cfg);
132 }
133 
134 /*
135  * Function to implement the pci_ops ->map_bus method
136  */
137 void __iomem *pci_ecam_map_bus(struct pci_bus *bus, unsigned int devfn,
138 			       int where)
139 {
140 	struct pci_config_window *cfg = bus->sysdata;
141 	unsigned int devfn_shift = cfg->ops->bus_shift - 8;
142 	unsigned int busn = bus->number;
143 	void __iomem *base;
144 
145 	if (busn < cfg->busr.start || busn > cfg->busr.end)
146 		return NULL;
147 
148 	busn -= cfg->busr.start;
149 	if (per_bus_mapping)
150 		base = cfg->winp[busn];
151 	else
152 		base = cfg->win + (busn << cfg->ops->bus_shift);
153 	return base + (devfn << devfn_shift) + where;
154 }
155 
156 /* ECAM ops */
157 struct pci_ecam_ops pci_generic_ecam_ops = {
158 	.bus_shift	= 20,
159 	.pci_ops	= {
160 		.map_bus	= pci_ecam_map_bus,
161 		.read		= pci_generic_config_read,
162 		.write		= pci_generic_config_write,
163 	}
164 };
165