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
19static 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
28static 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))) {
35err:		*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
62static 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
94const struct pci_raw_ops pci_mmcfg = {
95	.read =		pci_mmcfg_read,
96	.write =	pci_mmcfg_write,
97};
98
99static 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
114int __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
129void __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
137int 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
148void 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