kernel-ark/arch/powerpc/platforms/pseries/pci.c
Mauricio Faria de Oliveira 2dd9c11b9d powerpc/pseries: use pci_host_bridge.release_fn() to kfree(phb)
This patch leverages 'struct pci_host_bridge' from the PCI subsystem
in order to free the pci_controller only after the last reference to
its devices is dropped (avoiding an oops in pcibios_release_device()
if the last reference is dropped after pcibios_free_controller()).

The patch relies on pci_host_bridge.release_fn() (and .release_data),
which is called automatically by the PCI subsystem when the root bus
is released (i.e., the last reference is dropped).  Those fields are
set via pci_set_host_bridge_release() (e.g. in the platform-specific
implementation of pcibios_root_bridge_prepare()).

It introduces the 'pcibios_free_controller_deferred()' .release_fn()
and it expects .release_data to hold a pointer to the pci_controller.

The function implictly calls 'pcibios_free_controller()', so an user
must *NOT* explicitly call it if using the new _deferred() callback.

The functionality is enabled for pseries (although it isn't platform
specific, and may be used by cxl).

Details on not-so-elegant design choices:

 - Use 'pci_host_bridge.release_data' field as pointer to associated
   'struct pci_controller' so *not* to 'pci_bus_to_host(bridge->bus)'
   in pcibios_free_controller_deferred().

   That's because pci_remove_root_bus() sets 'host_bridge->bus = NULL'
   (so, if the last reference is released after pci_remove_root_bus()
   runs, which eventually reaches pcibios_free_controller_deferred(),
   that would hit a null pointer dereference).

   The cxl/vphb.c code calls pci_remove_root_bus(), and the cxl folks
   are interested in this fix.

Test-case #1 (hold references)

  # ls -ld /sys/block/sd* | grep -m1 0021:01:00.0
  <...> /sys/block/sdaa -> ../devices/pci0021:01/0021:01:00.0/<...>

  # ls -ld /sys/block/sd* | grep -m1 0021:01:00.1
  <...> /sys/block/sdab -> ../devices/pci0021:01/0021:01:00.1/<...>

  # cat >/dev/sdaa & pid1=$!
  # cat >/dev/sdab & pid2=$!

  # drmgr -w 5 -d 1 -c phb -s 'PHB 33' -r
  Validating PHB DLPAR capability...yes.
  [  594.306719] pci_hp_remove_devices: PCI: Removing devices on bus 0021:01
  [  594.306738] pci_hp_remove_devices:    Removing 0021:01:00.0...
  ...
  [  598.236381] pci_hp_remove_devices:    Removing 0021:01:00.1...
  ...
  [  611.972077] pci_bus 0021:01: busn_res: [bus 01-ff] is released
  [  611.972140] rpadlpar_io: slot PHB 33 removed

  # kill -9 $pid1
  # kill -9 $pid2
  [  632.918088] pcibios_free_controller_deferred: domain 33, dynamic 1

Test-case #2 (don't hold references)

  # drmgr -w 5 -d 1 -c phb -s 'PHB 33' -r
  Validating PHB DLPAR capability...yes.
  [  916.357363] pci_hp_remove_devices: PCI: Removing devices on bus 0021:01
  [  916.357386] pci_hp_remove_devices:    Removing 0021:01:00.0...
  ...
  [  920.566527] pci_hp_remove_devices:    Removing 0021:01:00.1...
  ...
  [  933.955873] pci_bus 0021:01: busn_res: [bus 01-ff] is released
  [  933.955977] pcibios_free_controller_deferred: domain 33, dynamic 1
  [  933.955999] rpadlpar_io: slot PHB 33 removed

Suggested-By: Gavin Shan <gwshan@linux.vnet.ibm.com>
Signed-off-by: Mauricio Faria de Oliveira <mauricfo@linux.vnet.ibm.com>
Reviewed-by: Gavin Shan <gwshan@linux.vnet.ibm.com>
Reviewed-by: Andrew Donnellan <andrew.donnellan@au1.ibm.com>
Tested-by: Andrew Donnellan <andrew.donnellan@au1.ibm.com> # cxl
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
2016-08-22 11:09:33 +10:00

177 lines
4.4 KiB
C

/*
* Copyright (C) 2001 Dave Engebretsen, IBM Corporation
* Copyright (C) 2003 Anton Blanchard <anton@au.ibm.com>, IBM
*
* pSeries specific routines for PCI.
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* 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 for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*/
#include <linux/init.h>
#include <linux/ioport.h>
#include <linux/kernel.h>
#include <linux/pci.h>
#include <linux/string.h>
#include <asm/eeh.h>
#include <asm/pci-bridge.h>
#include <asm/prom.h>
#include <asm/ppc-pci.h>
#include "pseries.h"
#if 0
void pcibios_name_device(struct pci_dev *dev)
{
struct device_node *dn;
/*
* Add IBM loc code (slot) as a prefix to the device names for service
*/
dn = pci_device_to_OF_node(dev);
if (dn) {
const char *loc_code = of_get_property(dn, "ibm,loc-code",
NULL);
if (loc_code) {
int loc_len = strlen(loc_code);
if (loc_len < sizeof(dev->dev.name)) {
memmove(dev->dev.name+loc_len+1, dev->dev.name,
sizeof(dev->dev.name)-loc_len-1);
memcpy(dev->dev.name, loc_code, loc_len);
dev->dev.name[loc_len] = ' ';
dev->dev.name[sizeof(dev->dev.name)-1] = '\0';
}
}
}
}
DECLARE_PCI_FIXUP_HEADER(PCI_ANY_ID, PCI_ANY_ID, pcibios_name_device);
#endif
static void __init pSeries_request_regions(void)
{
if (!isa_io_base)
return;
request_region(0x20,0x20,"pic1");
request_region(0xa0,0x20,"pic2");
request_region(0x00,0x20,"dma1");
request_region(0x40,0x20,"timer");
request_region(0x80,0x10,"dma page reg");
request_region(0xc0,0x20,"dma2");
}
void __init pSeries_final_fixup(void)
{
pSeries_request_regions();
eeh_addr_cache_build();
}
/*
* Assume the winbond 82c105 is the IDE controller on a
* p610/p615/p630. We should probably be more careful in case
* someone tries to plug in a similar adapter.
*/
static void fixup_winbond_82c105(struct pci_dev* dev)
{
int i;
unsigned int reg;
if (!machine_is(pseries))
return;
printk("Using INTC for W82c105 IDE controller.\n");
pci_read_config_dword(dev, 0x40, &reg);
/* Enable LEGIRQ to use INTC instead of ISA interrupts */
pci_write_config_dword(dev, 0x40, reg | (1<<11));
for (i = 0; i < DEVICE_COUNT_RESOURCE; ++i) {
/* zap the 2nd function of the winbond chip */
if (dev->resource[i].flags & IORESOURCE_IO
&& dev->bus->number == 0 && dev->devfn == 0x81)
dev->resource[i].flags &= ~IORESOURCE_IO;
if (dev->resource[i].start == 0 && dev->resource[i].end) {
dev->resource[i].flags = 0;
dev->resource[i].end = 0;
}
}
}
DECLARE_PCI_FIXUP_HEADER(PCI_VENDOR_ID_WINBOND, PCI_DEVICE_ID_WINBOND_82C105,
fixup_winbond_82c105);
int pseries_root_bridge_prepare(struct pci_host_bridge *bridge)
{
struct device_node *dn, *pdn;
struct pci_bus *bus;
u32 pcie_link_speed_stats[2];
int rc;
bus = bridge->bus;
/* Rely on the pcibios_free_controller_deferred() callback. */
pci_set_host_bridge_release(bridge, pcibios_free_controller_deferred,
(void *) pci_bus_to_host(bus));
dn = pcibios_get_phb_of_node(bus);
if (!dn)
return 0;
for (pdn = dn; pdn != NULL; pdn = of_get_next_parent(pdn)) {
rc = of_property_read_u32_array(pdn,
"ibm,pcie-link-speed-stats",
&pcie_link_speed_stats[0], 2);
if (!rc)
break;
}
of_node_put(pdn);
if (rc) {
pr_debug("no ibm,pcie-link-speed-stats property\n");
return 0;
}
switch (pcie_link_speed_stats[0]) {
case 0x01:
bus->max_bus_speed = PCIE_SPEED_2_5GT;
break;
case 0x02:
bus->max_bus_speed = PCIE_SPEED_5_0GT;
break;
case 0x04:
bus->max_bus_speed = PCIE_SPEED_8_0GT;
break;
default:
bus->max_bus_speed = PCI_SPEED_UNKNOWN;
break;
}
switch (pcie_link_speed_stats[1]) {
case 0x01:
bus->cur_bus_speed = PCIE_SPEED_2_5GT;
break;
case 0x02:
bus->cur_bus_speed = PCIE_SPEED_5_0GT;
break;
case 0x04:
bus->cur_bus_speed = PCIE_SPEED_8_0GT;
break;
default:
bus->cur_bus_speed = PCI_SPEED_UNKNOWN;
break;
}
return 0;
}