xref: /linux/arch/x86/pci/mmconfig_64.c (revision c4ee0af3fa0dc65f690fc908f02b8355f9576ea0)
1 /*
2  * mmconfig.c - Low-level direct PCI config space access via MMCONFIG
3  *
4  * This is an 64bit optimized version that always keeps the full mmconfig
5  * space mapped. This allows lockless config space operation.
6  */
7 
8 #include <linux/pci.h>
9 #include <linux/init.h>
10 #include <linux/acpi.h>
11 #include <linux/bitmap.h>
12 #include <linux/rcupdate.h>
13 #include <asm/e820.h>
14 #include <asm/pci_x86.h>
15 
16 #define PREFIX "PCI: "
17 
18 static char __iomem *pci_dev_base(unsigned int seg, unsigned int bus, unsigned int devfn)
19 {
20 	struct pci_mmcfg_region *cfg = pci_mmconfig_lookup(seg, bus);
21 
22 	if (cfg && cfg->virt)
23 		return cfg->virt + (PCI_MMCFG_BUS_OFFSET(bus) | (devfn << 12));
24 	return NULL;
25 }
26 
27 static int pci_mmcfg_read(unsigned int seg, unsigned int bus,
28 			  unsigned int devfn, int reg, int len, u32 *value)
29 {
30 	char __iomem *addr;
31 
32 	/* Why do we have this when nobody checks it. How about a BUG()!? -AK */
33 	if (unlikely((bus > 255) || (devfn > 255) || (reg > 4095))) {
34 err:		*value = -1;
35 		return -EINVAL;
36 	}
37 
38 	rcu_read_lock();
39 	addr = pci_dev_base(seg, bus, devfn);
40 	if (!addr) {
41 		rcu_read_unlock();
42 		goto err;
43 	}
44 
45 	switch (len) {
46 	case 1:
47 		*value = mmio_config_readb(addr + reg);
48 		break;
49 	case 2:
50 		*value = mmio_config_readw(addr + reg);
51 		break;
52 	case 4:
53 		*value = mmio_config_readl(addr + reg);
54 		break;
55 	}
56 	rcu_read_unlock();
57 
58 	return 0;
59 }
60 
61 static int pci_mmcfg_write(unsigned int seg, unsigned int bus,
62 			   unsigned int devfn, int reg, int len, u32 value)
63 {
64 	char __iomem *addr;
65 
66 	/* Why do we have this when nobody checks it. How about a BUG()!? -AK */
67 	if (unlikely((bus > 255) || (devfn > 255) || (reg > 4095)))
68 		return -EINVAL;
69 
70 	rcu_read_lock();
71 	addr = pci_dev_base(seg, bus, devfn);
72 	if (!addr) {
73 		rcu_read_unlock();
74 		return -EINVAL;
75 	}
76 
77 	switch (len) {
78 	case 1:
79 		mmio_config_writeb(addr + reg, value);
80 		break;
81 	case 2:
82 		mmio_config_writew(addr + reg, value);
83 		break;
84 	case 4:
85 		mmio_config_writel(addr + reg, value);
86 		break;
87 	}
88 	rcu_read_unlock();
89 
90 	return 0;
91 }
92 
93 const struct pci_raw_ops pci_mmcfg = {
94 	.read =		pci_mmcfg_read,
95 	.write =	pci_mmcfg_write,
96 };
97 
98 static void __iomem *mcfg_ioremap(struct pci_mmcfg_region *cfg)
99 {
100 	void __iomem *addr;
101 	u64 start, size;
102 	int num_buses;
103 
104 	start = cfg->address + PCI_MMCFG_BUS_OFFSET(cfg->start_bus);
105 	num_buses = cfg->end_bus - cfg->start_bus + 1;
106 	size = PCI_MMCFG_BUS_OFFSET(num_buses);
107 	addr = ioremap_nocache(start, size);
108 	if (addr)
109 		addr -= PCI_MMCFG_BUS_OFFSET(cfg->start_bus);
110 	return addr;
111 }
112 
113 int __init pci_mmcfg_arch_init(void)
114 {
115 	struct pci_mmcfg_region *cfg;
116 
117 	list_for_each_entry(cfg, &pci_mmcfg_list, list)
118 		if (pci_mmcfg_arch_map(cfg)) {
119 			pci_mmcfg_arch_free();
120 			return 0;
121 		}
122 
123 	raw_pci_ext_ops = &pci_mmcfg;
124 
125 	return 1;
126 }
127 
128 void __init pci_mmcfg_arch_free(void)
129 {
130 	struct pci_mmcfg_region *cfg;
131 
132 	list_for_each_entry(cfg, &pci_mmcfg_list, list)
133 		pci_mmcfg_arch_unmap(cfg);
134 }
135 
136 int pci_mmcfg_arch_map(struct pci_mmcfg_region *cfg)
137 {
138 	cfg->virt = mcfg_ioremap(cfg);
139 	if (!cfg->virt) {
140 		pr_err(PREFIX "can't map MMCONFIG at %pR\n", &cfg->res);
141 		return -ENOMEM;
142 	}
143 
144 	return 0;
145 }
146 
147 void pci_mmcfg_arch_unmap(struct pci_mmcfg_region *cfg)
148 {
149 	if (cfg && cfg->virt) {
150 		iounmap(cfg->virt + PCI_MMCFG_BUS_OFFSET(cfg->start_bus));
151 		cfg->virt = NULL;
152 	}
153 }
154