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// SPDX-License-Identifier: GPL-2.0
/*
* mmconfig.c - Low-level direct PCI config space access via MMCONFIG
*
* This is an 64bit optimized version that always keeps the full mmconfig
* space mapped. This allows lockless config space operation.
*/
#include <linux/pci.h>
#include <linux/init.h>
#include <linux/acpi.h>
#include <linux/bitmap.h>
#include <linux/rcupdate.h>
#include <asm/e820/api.h>
#include <asm/pci_x86.h>
#define PREFIX "PCI: "
static char __iomem *pci_dev_base(unsigned int seg, unsigned int bus, unsigned int devfn)
{
struct pci_mmcfg_region *cfg = pci_mmconfig_lookup(seg, bus);
if (cfg && cfg->virt)
return cfg->virt + (PCI_MMCFG_BUS_OFFSET(bus) | (devfn << 12));
return NULL;
}
static int pci_mmcfg_read(unsigned int seg, unsigned int bus,
unsigned int devfn, int reg, int len, u32 *value)
{
char __iomem *addr;
/* Why do we have this when nobody checks it. How about a BUG()!? -AK */
if (unlikely((bus > 255) || (devfn > 255) || (reg > 4095))) {
err: *value = -1;
return -EINVAL;
}
rcu_read_lock();
addr = pci_dev_base(seg, bus, devfn);
if (!addr) {
rcu_read_unlock();
goto err;
}
switch (len) {
case 1:
*value = mmio_config_readb(addr + reg);
break;
case 2:
*value = mmio_config_readw(addr + reg);
break;
case 4:
*value = mmio_config_readl(addr + reg);
break;
}
rcu_read_unlock();
return 0;
}
static int pci_mmcfg_write(unsigned int seg, unsigned int bus,
unsigned int devfn, int reg, int len, u32 value)
{
char __iomem *addr;
/* Why do we have this when nobody checks it. How about a BUG()!? -AK */
if (unlikely((bus > 255) || (devfn > 255) || (reg > 4095)))
return -EINVAL;
rcu_read_lock();
addr = pci_dev_base(seg, bus, devfn);
if (!addr) {
rcu_read_unlock();
return -EINVAL;
}
switch (len) {
case 1:
mmio_config_writeb(addr + reg, value);
break;
case 2:
mmio_config_writew(addr + reg, value);
break;
case 4:
mmio_config_writel(addr + reg, value);
break;
}
rcu_read_unlock();
return 0;
}
const struct pci_raw_ops pci_mmcfg = {
.read = pci_mmcfg_read,
.write = pci_mmcfg_write,
};
static void __iomem *mcfg_ioremap(struct pci_mmcfg_region *cfg)
{
void __iomem *addr;
u64 start, size;
int num_buses;
start = cfg->address + PCI_MMCFG_BUS_OFFSET(cfg->start_bus);
num_buses = cfg->end_bus - cfg->start_bus + 1;
size = PCI_MMCFG_BUS_OFFSET(num_buses);
addr = ioremap_nocache(start, size);
if (addr)
addr -= PCI_MMCFG_BUS_OFFSET(cfg->start_bus);
return addr;
}
int __init pci_mmcfg_arch_init(void)
{
struct pci_mmcfg_region *cfg;
list_for_each_entry(cfg, &pci_mmcfg_list, list)
if (pci_mmcfg_arch_map(cfg)) {
pci_mmcfg_arch_free();
return 0;
}
raw_pci_ext_ops = &pci_mmcfg;
return 1;
}
void __init pci_mmcfg_arch_free(void)
{
struct pci_mmcfg_region *cfg;
list_for_each_entry(cfg, &pci_mmcfg_list, list)
pci_mmcfg_arch_unmap(cfg);
}
int pci_mmcfg_arch_map(struct pci_mmcfg_region *cfg)
{
cfg->virt = mcfg_ioremap(cfg);
if (!cfg->virt) {
pr_err(PREFIX "can't map MMCONFIG at %pR\n", &cfg->res);
return -ENOMEM;
}
return 0;
}
void pci_mmcfg_arch_unmap(struct pci_mmcfg_region *cfg)
{
if (cfg && cfg->virt) {
iounmap(cfg->virt + PCI_MMCFG_BUS_OFFSET(cfg->start_bus));
cfg->virt = NULL;
}
}
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