xref: /openbmc/linux/arch/x86/pci/mmconfig_64.c (revision 4bdc0d67)
1 // SPDX-License-Identifier: GPL-2.0
2 /*
3  * mmconfig.c - Low-level direct PCI config space access via MMCONFIG
4  *
5  * This is an 64bit optimized version that always keeps the full mmconfig
6  * space mapped. This allows lockless config space operation.
7  */
8 
9 #include <linux/pci.h>
10 #include <linux/init.h>
11 #include <linux/acpi.h>
12 #include <linux/bitmap.h>
13 #include <linux/rcupdate.h>
14 #include <asm/e820/api.h>
15 #include <asm/pci_x86.h>
16 
17 #define PREFIX "PCI: "
18 
pci_dev_base(unsigned int seg,unsigned int bus,unsigned int devfn)19 static char __iomem *pci_dev_base(unsigned int seg, unsigned int bus, unsigned int devfn)
20 {
21 	struct pci_mmcfg_region *cfg = pci_mmconfig_lookup(seg, bus);
22 
23 	if (cfg && cfg->virt)
24 		return cfg->virt + (PCI_MMCFG_BUS_OFFSET(bus) | (devfn << 12));
25 	return NULL;
26 }
27 
pci_mmcfg_read(unsigned int seg,unsigned int bus,unsigned int devfn,int reg,int len,u32 * value)28 static int pci_mmcfg_read(unsigned int seg, unsigned int bus,
29 			  unsigned int devfn, int reg, int len, u32 *value)
30 {
31 	char __iomem *addr;
32 
33 	/* Why do we have this when nobody checks it. How about a BUG()!? -AK */
34 	if (unlikely((bus > 255) || (devfn > 255) || (reg > 4095))) {
35 err:		*value = -1;
36 		return -EINVAL;
37 	}
38 
39 	rcu_read_lock();
40 	addr = pci_dev_base(seg, bus, devfn);
41 	if (!addr) {
42 		rcu_read_unlock();
43 		goto err;
44 	}
45 
46 	switch (len) {
47 	case 1:
48 		*value = mmio_config_readb(addr + reg);
49 		break;
50 	case 2:
51 		*value = mmio_config_readw(addr + reg);
52 		break;
53 	case 4:
54 		*value = mmio_config_readl(addr + reg);
55 		break;
56 	}
57 	rcu_read_unlock();
58 
59 	return 0;
60 }
61 
pci_mmcfg_write(unsigned int seg,unsigned int bus,unsigned int devfn,int reg,int len,u32 value)62 static int pci_mmcfg_write(unsigned int seg, unsigned int bus,
63 			   unsigned int devfn, int reg, int len, u32 value)
64 {
65 	char __iomem *addr;
66 
67 	/* Why do we have this when nobody checks it. How about a BUG()!? -AK */
68 	if (unlikely((bus > 255) || (devfn > 255) || (reg > 4095)))
69 		return -EINVAL;
70 
71 	rcu_read_lock();
72 	addr = pci_dev_base(seg, bus, devfn);
73 	if (!addr) {
74 		rcu_read_unlock();
75 		return -EINVAL;
76 	}
77 
78 	switch (len) {
79 	case 1:
80 		mmio_config_writeb(addr + reg, value);
81 		break;
82 	case 2:
83 		mmio_config_writew(addr + reg, value);
84 		break;
85 	case 4:
86 		mmio_config_writel(addr + reg, value);
87 		break;
88 	}
89 	rcu_read_unlock();
90 
91 	return 0;
92 }
93 
94 const struct pci_raw_ops pci_mmcfg = {
95 	.read =		pci_mmcfg_read,
96 	.write =	pci_mmcfg_write,
97 };
98 
mcfg_ioremap(struct pci_mmcfg_region * cfg)99 static void __iomem *mcfg_ioremap(struct pci_mmcfg_region *cfg)
100 {
101 	void __iomem *addr;
102 	u64 start, size;
103 	int num_buses;
104 
105 	start = cfg->address + PCI_MMCFG_BUS_OFFSET(cfg->start_bus);
106 	num_buses = cfg->end_bus - cfg->start_bus + 1;
107 	size = PCI_MMCFG_BUS_OFFSET(num_buses);
108 	addr = ioremap(start, size);
109 	if (addr)
110 		addr -= PCI_MMCFG_BUS_OFFSET(cfg->start_bus);
111 	return addr;
112 }
113 
pci_mmcfg_arch_init(void)114 int __init pci_mmcfg_arch_init(void)
115 {
116 	struct pci_mmcfg_region *cfg;
117 
118 	list_for_each_entry(cfg, &pci_mmcfg_list, list)
119 		if (pci_mmcfg_arch_map(cfg)) {
120 			pci_mmcfg_arch_free();
121 			return 0;
122 		}
123 
124 	raw_pci_ext_ops = &pci_mmcfg;
125 
126 	return 1;
127 }
128 
pci_mmcfg_arch_free(void)129 void __init pci_mmcfg_arch_free(void)
130 {
131 	struct pci_mmcfg_region *cfg;
132 
133 	list_for_each_entry(cfg, &pci_mmcfg_list, list)
134 		pci_mmcfg_arch_unmap(cfg);
135 }
136 
pci_mmcfg_arch_map(struct pci_mmcfg_region * cfg)137 int pci_mmcfg_arch_map(struct pci_mmcfg_region *cfg)
138 {
139 	cfg->virt = mcfg_ioremap(cfg);
140 	if (!cfg->virt) {
141 		pr_err(PREFIX "can't map MMCONFIG at %pR\n", &cfg->res);
142 		return -ENOMEM;
143 	}
144 
145 	return 0;
146 }
147 
pci_mmcfg_arch_unmap(struct pci_mmcfg_region * cfg)148 void pci_mmcfg_arch_unmap(struct pci_mmcfg_region *cfg)
149 {
150 	if (cfg && cfg->virt) {
151 		iounmap(cfg->virt + PCI_MMCFG_BUS_OFFSET(cfg->start_bus));
152 		cfg->virt = NULL;
153 	}
154 }
155