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
pci_dev_base(unsigned int seg,unsigned int bus,unsigned int devfn)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
pci_mmcfg_read(unsigned int seg,unsigned int bus,unsigned int devfn,int reg,int len,u32 * value)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
pci_mmcfg_write(unsigned int seg,unsigned int bus,unsigned int devfn,int reg,int len,u32 value)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
mcfg_ioremap(struct pci_mmcfg_region * cfg)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
pci_mmcfg_arch_init(void)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
pci_mmcfg_arch_free(void)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
pci_mmcfg_arch_map(struct pci_mmcfg_region * cfg)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
pci_mmcfg_arch_unmap(struct pci_mmcfg_region * cfg)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