linux/drivers/pci/ecam.c
Lorenzo Pieralisi 053497cec7 PCI: ECAM: Map config region with pci_remap_cfgspace()
The current ECAM kernel implementation uses ioremap() to map the ECAM
configuration space memory region; this is not safe in that on some
architectures the ioremap interface provides mappings that allow posted
write transactions. This, as highlighted in the PCIe specifications (4.0 -
Rev0.3, "Ordering Considerations for the Enhanced Configuration Address
Mechanism"), can create ordering issues for software because posted writes
transactions on the CPU host bus are non posted in the PCI express fabric.

Update the ioremap() interface to use pci_remap_cfgspace() whose mapping
attributes guarantee that non-posted writes transactions are issued for
memory writes within the ECAM memory mapped address region.

Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Cc: Jayachandran C <jnair@caviumnetworks.com>
2017-04-24 13:53:14 -05:00

179 lines
4.5 KiB
C

/*
* Copyright 2016 Broadcom
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License, version 2, as
* published by the Free Software Foundation (the "GPL").
*
* This program is distributed in the hope that it will be useful, but
* WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* General Public License version 2 (GPLv2) for more details.
*
* You should have received a copy of the GNU General Public License
* version 2 (GPLv2) along with this source code.
*/
#include <linux/device.h>
#include <linux/io.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/pci.h>
#include <linux/pci-ecam.h>
#include <linux/slab.h>
/*
* On 64-bit systems, we do a single ioremap for the whole config space
* since we have enough virtual address range available. On 32-bit, we
* ioremap the config space for each bus individually.
*/
static const bool per_bus_mapping = !IS_ENABLED(CONFIG_64BIT);
/*
* Create a PCI config space window
* - reserve mem region
* - alloc struct pci_config_window with space for all mappings
* - ioremap the config space
*/
struct pci_config_window *pci_ecam_create(struct device *dev,
struct resource *cfgres, struct resource *busr,
struct pci_ecam_ops *ops)
{
struct pci_config_window *cfg;
unsigned int bus_range, bus_range_max, bsz;
struct resource *conflict;
int i, err;
if (busr->start > busr->end)
return ERR_PTR(-EINVAL);
cfg = kzalloc(sizeof(*cfg), GFP_KERNEL);
if (!cfg)
return ERR_PTR(-ENOMEM);
cfg->parent = dev;
cfg->ops = ops;
cfg->busr.start = busr->start;
cfg->busr.end = busr->end;
cfg->busr.flags = IORESOURCE_BUS;
bus_range = resource_size(&cfg->busr);
bus_range_max = resource_size(cfgres) >> ops->bus_shift;
if (bus_range > bus_range_max) {
bus_range = bus_range_max;
cfg->busr.end = busr->start + bus_range - 1;
dev_warn(dev, "ECAM area %pR can only accommodate %pR (reduced from %pR desired)\n",
cfgres, &cfg->busr, busr);
}
bsz = 1 << ops->bus_shift;
cfg->res.start = cfgres->start;
cfg->res.end = cfgres->end;
cfg->res.flags = IORESOURCE_MEM | IORESOURCE_BUSY;
cfg->res.name = "PCI ECAM";
conflict = request_resource_conflict(&iomem_resource, &cfg->res);
if (conflict) {
err = -EBUSY;
dev_err(dev, "can't claim ECAM area %pR: address conflict with %s %pR\n",
&cfg->res, conflict->name, conflict);
goto err_exit;
}
if (per_bus_mapping) {
cfg->winp = kcalloc(bus_range, sizeof(*cfg->winp), GFP_KERNEL);
if (!cfg->winp)
goto err_exit_malloc;
for (i = 0; i < bus_range; i++) {
cfg->winp[i] =
pci_remap_cfgspace(cfgres->start + i * bsz,
bsz);
if (!cfg->winp[i])
goto err_exit_iomap;
}
} else {
cfg->win = pci_remap_cfgspace(cfgres->start, bus_range * bsz);
if (!cfg->win)
goto err_exit_iomap;
}
if (ops->init) {
err = ops->init(cfg);
if (err)
goto err_exit;
}
dev_info(dev, "ECAM at %pR for %pR\n", &cfg->res, &cfg->busr);
return cfg;
err_exit_iomap:
dev_err(dev, "ECAM ioremap failed\n");
err_exit_malloc:
err = -ENOMEM;
err_exit:
pci_ecam_free(cfg);
return ERR_PTR(err);
}
void pci_ecam_free(struct pci_config_window *cfg)
{
int i;
if (per_bus_mapping) {
if (cfg->winp) {
for (i = 0; i < resource_size(&cfg->busr); i++)
if (cfg->winp[i])
iounmap(cfg->winp[i]);
kfree(cfg->winp);
}
} else {
if (cfg->win)
iounmap(cfg->win);
}
if (cfg->res.parent)
release_resource(&cfg->res);
kfree(cfg);
}
/*
* Function to implement the pci_ops ->map_bus method
*/
void __iomem *pci_ecam_map_bus(struct pci_bus *bus, unsigned int devfn,
int where)
{
struct pci_config_window *cfg = bus->sysdata;
unsigned int devfn_shift = cfg->ops->bus_shift - 8;
unsigned int busn = bus->number;
void __iomem *base;
if (busn < cfg->busr.start || busn > cfg->busr.end)
return NULL;
busn -= cfg->busr.start;
if (per_bus_mapping)
base = cfg->winp[busn];
else
base = cfg->win + (busn << cfg->ops->bus_shift);
return base + (devfn << devfn_shift) + where;
}
/* ECAM ops */
struct pci_ecam_ops pci_generic_ecam_ops = {
.bus_shift = 20,
.pci_ops = {
.map_bus = pci_ecam_map_bus,
.read = pci_generic_config_read,
.write = pci_generic_config_write,
}
};
#if defined(CONFIG_ACPI) && defined(CONFIG_PCI_QUIRKS)
/* ECAM ops for 32-bit access only (non-compliant) */
struct pci_ecam_ops pci_32b_ops = {
.bus_shift = 20,
.pci_ops = {
.map_bus = pci_ecam_map_bus,
.read = pci_generic_config_read32,
.write = pci_generic_config_write32,
}
};
#endif