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kernel-fxtec-pro1x/arch/powerpc/platforms/pseries/eeh_driver.c
Mike Mason c58dc575f3 powerpc/pseries: Set error_state to pci_channel_io_normal in eeh_report_reset() 
While adding native EEH support to Emulex and Qlogic drivers, it was
discovered that dev->error_state was set to pci_io_channel_normal too
late in the recovery process. These drivers rely on error_state to
determine if they can access the device in their slot_reset callback,
thus error_state needs to be set to pci_io_channel_normal in
eeh_report_reset(). Below is a detailed explanation (courtesy of Richard
Lary) as to why this is necessary.

Background:
PCI MMIO or DMA accesses to a frozen slot generate additional EEH
errors. If the number of additional EEH errors exceeds EEH_MAX_FAILS the
adapter will be shutdown. To avoid triggering excessive EEH errors and
an undesirable adapter shutdown, some drivers use the
pci_channel_offline(dev) wrapper function to return a Boolean value
based on the value of pci_dev->error_state to determine if PCI MMIO or
DMA accesses are safe. If the wrapper returns TRUE, drivers must not
make PCI MMIO or DMA access to their hardware.

The pci_dev structure member error_state reflects one of three values,
1) pci_channel_io_normal, 2) pci_channel_io_frozen, 3)
pci_channel_io_perm_failure.  Function pci_channel_offline(dev) returns
TRUE if error_state is pci_channel_io_frozen or pci_channel_io_perm_failure.

The EEH driver sets pci_dev->error_state to pci_channel_io_frozen at the
point where the PCI slot is frozen. Currently, the EEH driver restores
dev->error_state to pci_channel_io_normal in eeh_report_resume() before
calling the driver's resume callback. However, when the EEH driver calls
the driver's slot_reset callback() from eeh_report_reset(), it
incorrectly indicates the error state is still pci_channel_io_frozen.

Waiting until eeh_report_resume() to restore dev->error_state to
pci_channel_io_normal is too late for Emulex and QLogic FC drivers and
any other drivers which are designed to use common code paths in these
two cases: i) those called after the driver's slot_reset callback() and
ii) those called after the PCI slot is frozen but before the driver's
slot_reset callback is called. Case i) all driver paths executed to
reinitialize the hardware after a reset and case ii) all code paths
executed by driver kernel threads that run asynchronous to the main
driver thread, such as interrupt handlers and worker threads to process
driver work queues.

Emulex and QLogic FC drivers are designed with common code paths which
require that pci_channel_offline(dev) reflect the true state of the
hardware. The state transitions that the hardware takes from Normal
Operations to Slot Frozen to Reset to Normal Operations are documented
in the Power Architecture™ Platform Requirements+ (PAPR+) in Table 75.
PE State Control.

PAPR defines the following 3 states:

0 -- Not reset, Not EEH stopped, MMIO load/store allowed, DMA allowed
     (Normal Operations)
1 -- Reset, Not EEH stopped, MMIO load/store disabled, DMA disabled
2 -- Not reset, EEH stopped, MMIO load/store disabled, DMA disabled
     (Slot Frozen)

An EEH error places the slot in state 2 (Frozen) and the adapter driver
is notified that an EEH error was detected. If the adapter driver
returns PCI_ERS_RESULT_NEED_RESET, the EEH driver calls
eeh_reset_device() to place the slot into state 1 (Reset) and
eeh_reset_device completes by placing the slot into State 0 (Normal
Operations). Upon return from eeh_reset_device(), the EEH driver calls
eeh_report_reset, which then calls the adapter's slot_reset callback. At
the time the adapter's slot_reset callback is called, the true state of
the hardware is Normal Operations and should be accurately reflected by
setting dev->error_state to pci_channel_io_normal.

The current implementation of EEH driver does not do so and requires
this change to correct this deficiency.

Signed-off-by: Mike Mason <mmlnx@us.ibm.com>
Acked-by: Linas Vepstas <linasvepstas@gmail.com>
Signed-off-by: Paul Mackerras <paulus@samba.org>
2009-04-15 15:23:53 +10:00

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/*
* PCI Error Recovery Driver for RPA-compliant PPC64 platform.
* Copyright IBM Corp. 2004 2005
* Copyright Linas Vepstas <linas@linas.org> 2004, 2005
*
* All rights reserved.
*
* 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, GOOD TITLE or
* NON INFRINGEMENT. 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., 675 Mass Ave, Cambridge, MA 02139, USA.
*
* Send comments and feedback to Linas Vepstas <linas@austin.ibm.com>
*/
#include <linux/delay.h>
#include <linux/interrupt.h>
#include <linux/irq.h>
#include <linux/pci.h>
#include <asm/eeh.h>
#include <asm/eeh_event.h>
#include <asm/ppc-pci.h>
#include <asm/pci-bridge.h>
#include <asm/prom.h>
#include <asm/rtas.h>
static inline const char * pcid_name (struct pci_dev *pdev)
{
if (pdev && pdev->dev.driver)
return pdev->dev.driver->name;
return "";
}
#if 0
static void print_device_node_tree(struct pci_dn *pdn, int dent)
{
int i;
struct device_node *pc;
if (!pdn)
return;
for (i = 0; i < dent; i++)
printk(" ");
printk("dn=%s mode=%x \tcfg_addr=%x pe_addr=%x \tfull=%s\n",
pdn->node->name, pdn->eeh_mode, pdn->eeh_config_addr,
pdn->eeh_pe_config_addr, pdn->node->full_name);
dent += 3;
pc = pdn->node->child;
while (pc) {
print_device_node_tree(PCI_DN(pc), dent);
pc = pc->sibling;
}
}
#endif
/**
* irq_in_use - return true if this irq is being used
*/
static int irq_in_use(unsigned int irq)
{
int rc = 0;
unsigned long flags;
struct irq_desc *desc = irq_desc + irq;
spin_lock_irqsave(&desc->lock, flags);
if (desc->action)
rc = 1;
spin_unlock_irqrestore(&desc->lock, flags);
return rc;
}
/**
* eeh_disable_irq - disable interrupt for the recovering device
*/
static void eeh_disable_irq(struct pci_dev *dev)
{
struct device_node *dn = pci_device_to_OF_node(dev);
/* Don't disable MSI and MSI-X interrupts. They are
* effectively disabled by the DMA Stopped state
* when an EEH error occurs.
*/
if (dev->msi_enabled || dev->msix_enabled)
return;
if (!irq_in_use(dev->irq))
return;
PCI_DN(dn)->eeh_mode |= EEH_MODE_IRQ_DISABLED;
disable_irq_nosync(dev->irq);
}
/**
* eeh_enable_irq - enable interrupt for the recovering device
*/
static void eeh_enable_irq(struct pci_dev *dev)
{
struct device_node *dn = pci_device_to_OF_node(dev);
if ((PCI_DN(dn)->eeh_mode) & EEH_MODE_IRQ_DISABLED) {
PCI_DN(dn)->eeh_mode &= ~EEH_MODE_IRQ_DISABLED;
enable_irq(dev->irq);
}
}
/* ------------------------------------------------------- */
/**
* eeh_report_error - report pci error to each device driver
*
* Report an EEH error to each device driver, collect up and
* merge the device driver responses. Cumulative response
* passed back in "userdata".
*/
static void eeh_report_error(struct pci_dev *dev, void *userdata)
{
enum pci_ers_result rc, *res = userdata;
struct pci_driver *driver = dev->driver;
dev->error_state = pci_channel_io_frozen;
if (!driver)
return;
eeh_disable_irq(dev);
if (!driver->err_handler ||
!driver->err_handler->error_detected)
return;
rc = driver->err_handler->error_detected (dev, pci_channel_io_frozen);
/* A driver that needs a reset trumps all others */
if (rc == PCI_ERS_RESULT_NEED_RESET) *res = rc;
if (*res == PCI_ERS_RESULT_NONE) *res = rc;
}
/**
* eeh_report_mmio_enabled - tell drivers that MMIO has been enabled
*
* Tells each device driver that IO ports, MMIO and config space I/O
* are now enabled. Collects up and merges the device driver responses.
* Cumulative response passed back in "userdata".
*/
static void eeh_report_mmio_enabled(struct pci_dev *dev, void *userdata)
{
enum pci_ers_result rc, *res = userdata;
struct pci_driver *driver = dev->driver;
if (!driver ||
!driver->err_handler ||
!driver->err_handler->mmio_enabled)
return;
rc = driver->err_handler->mmio_enabled (dev);
/* A driver that needs a reset trumps all others */
if (rc == PCI_ERS_RESULT_NEED_RESET) *res = rc;
if (*res == PCI_ERS_RESULT_NONE) *res = rc;
}
/**
* eeh_report_reset - tell device that slot has been reset
*/
static void eeh_report_reset(struct pci_dev *dev, void *userdata)
{
enum pci_ers_result rc, *res = userdata;
struct pci_driver *driver = dev->driver;
if (!driver)
return;
dev->error_state = pci_channel_io_normal;
eeh_enable_irq(dev);
if (!driver->err_handler ||
!driver->err_handler->slot_reset)
return;
rc = driver->err_handler->slot_reset(dev);
if ((*res == PCI_ERS_RESULT_NONE) ||
(*res == PCI_ERS_RESULT_RECOVERED)) *res = rc;
if (*res == PCI_ERS_RESULT_DISCONNECT &&
rc == PCI_ERS_RESULT_NEED_RESET) *res = rc;
}
/**
* eeh_report_resume - tell device to resume normal operations
*/
static void eeh_report_resume(struct pci_dev *dev, void *userdata)
{
struct pci_driver *driver = dev->driver;
dev->error_state = pci_channel_io_normal;
if (!driver)
return;
eeh_enable_irq(dev);
if (!driver->err_handler ||
!driver->err_handler->resume)
return;
driver->err_handler->resume(dev);
}
/**
* eeh_report_failure - tell device driver that device is dead.
*
* This informs the device driver that the device is permanently
* dead, and that no further recovery attempts will be made on it.
*/
static void eeh_report_failure(struct pci_dev *dev, void *userdata)
{
struct pci_driver *driver = dev->driver;
dev->error_state = pci_channel_io_perm_failure;
if (!driver)
return;
eeh_disable_irq(dev);
if (!driver->err_handler ||
!driver->err_handler->error_detected)
return;
driver->err_handler->error_detected(dev, pci_channel_io_perm_failure);
}
/* ------------------------------------------------------- */
/**
* handle_eeh_events -- reset a PCI device after hard lockup.
*
* pSeries systems will isolate a PCI slot if the PCI-Host
* bridge detects address or data parity errors, DMA's
* occurring to wild addresses (which usually happen due to
* bugs in device drivers or in PCI adapter firmware).
* Slot isolations also occur if #SERR, #PERR or other misc
* PCI-related errors are detected.
*
* Recovery process consists of unplugging the device driver
* (which generated hotplug events to userspace), then issuing
* a PCI #RST to the device, then reconfiguring the PCI config
* space for all bridges & devices under this slot, and then
* finally restarting the device drivers (which cause a second
* set of hotplug events to go out to userspace).
*/
/**
* eeh_reset_device() -- perform actual reset of a pci slot
* @bus: pointer to the pci bus structure corresponding
* to the isolated slot. A non-null value will
* cause all devices under the bus to be removed
* and then re-added.
* @pe_dn: pointer to a "Partionable Endpoint" device node.
* This is the top-level structure on which pci
* bus resets can be performed.
*/
static int eeh_reset_device (struct pci_dn *pe_dn, struct pci_bus *bus)
{
struct device_node *dn;
int cnt, rc;
/* pcibios will clear the counter; save the value */
cnt = pe_dn->eeh_freeze_count;
if (bus)
pcibios_remove_pci_devices(bus);
/* Reset the pci controller. (Asserts RST#; resets config space).
* Reconfigure bridges and devices. Don't try to bring the system
* up if the reset failed for some reason. */
rc = rtas_set_slot_reset(pe_dn);
if (rc)
return rc;
/* Walk over all functions on this device. */
dn = pe_dn->node;
if (!pcibios_find_pci_bus(dn) && PCI_DN(dn->parent))
dn = dn->parent->child;
while (dn) {
struct pci_dn *ppe = PCI_DN(dn);
/* On Power4, always true because eeh_pe_config_addr=0 */
if (pe_dn->eeh_pe_config_addr == ppe->eeh_pe_config_addr) {
rtas_configure_bridge(ppe);
eeh_restore_bars(ppe);
}
dn = dn->sibling;
}
/* Give the system 5 seconds to finish running the user-space
* hotplug shutdown scripts, e.g. ifdown for ethernet. Yes,
* this is a hack, but if we don't do this, and try to bring
* the device up before the scripts have taken it down,
* potentially weird things happen.
*/
if (bus) {
ssleep (5);
pcibios_add_pci_devices(bus);
}
pe_dn->eeh_freeze_count = cnt;
return 0;
}
/* The longest amount of time to wait for a pci device
* to come back on line, in seconds.
*/
#define MAX_WAIT_FOR_RECOVERY 150
struct pci_dn * handle_eeh_events (struct eeh_event *event)
{
struct device_node *frozen_dn;
struct pci_dn *frozen_pdn;
struct pci_bus *frozen_bus;
int rc = 0;
enum pci_ers_result result = PCI_ERS_RESULT_NONE;
const char *location, *pci_str, *drv_str;
frozen_dn = find_device_pe(event->dn);
if (!frozen_dn) {
location = of_get_property(event->dn, "ibm,loc-code", NULL);
location = location ? location : "unknown";
printk(KERN_ERR "EEH: Error: Cannot find partition endpoint "
"for location=%s pci addr=%s\n",
location, pci_name(event->dev));
return NULL;
}
frozen_bus = pcibios_find_pci_bus(frozen_dn);
location = of_get_property(frozen_dn, "ibm,loc-code", NULL);
location = location ? location : "unknown";
/* There are two different styles for coming up with the PE.
* In the old style, it was the highest EEH-capable device
* which was always an EADS pci bridge. In the new style,
* there might not be any EADS bridges, and even when there are,
* the firmware marks them as "EEH incapable". So another
* two-step is needed to find the pci bus.. */
if (!frozen_bus)
frozen_bus = pcibios_find_pci_bus (frozen_dn->parent);
if (!frozen_bus) {
printk(KERN_ERR "EEH: Cannot find PCI bus "
"for location=%s dn=%s\n",
location, frozen_dn->full_name);
return NULL;
}
frozen_pdn = PCI_DN(frozen_dn);
frozen_pdn->eeh_freeze_count++;
if (frozen_pdn->pcidev) {
pci_str = pci_name (frozen_pdn->pcidev);
drv_str = pcid_name (frozen_pdn->pcidev);
} else {
pci_str = pci_name (event->dev);
drv_str = pcid_name (event->dev);
}
if (frozen_pdn->eeh_freeze_count > EEH_MAX_ALLOWED_FREEZES)
goto excess_failures;
printk(KERN_WARNING
"EEH: This PCI device has failed %d times in the last hour:\n",
frozen_pdn->eeh_freeze_count);
printk(KERN_WARNING
"EEH: location=%s driver=%s pci addr=%s\n",
location, drv_str, pci_str);
/* Walk the various device drivers attached to this slot through
* a reset sequence, giving each an opportunity to do what it needs
* to accomplish the reset. Each child gets a report of the
* status ... if any child can't handle the reset, then the entire
* slot is dlpar removed and added.
*/
pci_walk_bus(frozen_bus, eeh_report_error, &result);
/* Get the current PCI slot state. This can take a long time,
* sometimes over 3 seconds for certain systems. */
rc = eeh_wait_for_slot_status (frozen_pdn, MAX_WAIT_FOR_RECOVERY*1000);
if (rc < 0) {
printk(KERN_WARNING "EEH: Permanent failure\n");
goto hard_fail;
}
/* Since rtas may enable MMIO when posting the error log,
* don't post the error log until after all dev drivers
* have been informed.
*/
eeh_slot_error_detail(frozen_pdn, EEH_LOG_TEMP_FAILURE);
/* If all device drivers were EEH-unaware, then shut
* down all of the device drivers, and hope they
* go down willingly, without panicing the system.
*/
if (result == PCI_ERS_RESULT_NONE) {
rc = eeh_reset_device(frozen_pdn, frozen_bus);
if (rc) {
printk(KERN_WARNING "EEH: Unable to reset, rc=%d\n", rc);
goto hard_fail;
}
}
/* If all devices reported they can proceed, then re-enable MMIO */
if (result == PCI_ERS_RESULT_CAN_RECOVER) {
rc = rtas_pci_enable(frozen_pdn, EEH_THAW_MMIO);
if (rc < 0)
goto hard_fail;
if (rc) {
result = PCI_ERS_RESULT_NEED_RESET;
} else {
result = PCI_ERS_RESULT_NONE;
pci_walk_bus(frozen_bus, eeh_report_mmio_enabled, &result);
}
}
/* If all devices reported they can proceed, then re-enable DMA */
if (result == PCI_ERS_RESULT_CAN_RECOVER) {
rc = rtas_pci_enable(frozen_pdn, EEH_THAW_DMA);
if (rc < 0)
goto hard_fail;
if (rc)
result = PCI_ERS_RESULT_NEED_RESET;
else
result = PCI_ERS_RESULT_RECOVERED;
}
/* If any device has a hard failure, then shut off everything. */
if (result == PCI_ERS_RESULT_DISCONNECT) {
printk(KERN_WARNING "EEH: Device driver gave up\n");
goto hard_fail;
}
/* If any device called out for a reset, then reset the slot */
if (result == PCI_ERS_RESULT_NEED_RESET) {
rc = eeh_reset_device(frozen_pdn, NULL);
if (rc) {
printk(KERN_WARNING "EEH: Cannot reset, rc=%d\n", rc);
goto hard_fail;
}
result = PCI_ERS_RESULT_NONE;
pci_walk_bus(frozen_bus, eeh_report_reset, &result);
}
/* All devices should claim they have recovered by now. */
if ((result != PCI_ERS_RESULT_RECOVERED) &&
(result != PCI_ERS_RESULT_NONE)) {
printk(KERN_WARNING "EEH: Not recovered\n");
goto hard_fail;
}
/* Tell all device drivers that they can resume operations */
pci_walk_bus(frozen_bus, eeh_report_resume, NULL);
return frozen_pdn;
excess_failures:
/*
* About 90% of all real-life EEH failures in the field
* are due to poorly seated PCI cards. Only 10% or so are
* due to actual, failed cards.
*/
printk(KERN_ERR
"EEH: PCI device at location=%s driver=%s pci addr=%s \n"
"has failed %d times in the last hour "
"and has been permanently disabled. \n"
"Please try reseating this device or replacing it.\n",
location, drv_str, pci_str, frozen_pdn->eeh_freeze_count);
goto perm_error;
hard_fail:
printk(KERN_ERR
"EEH: Unable to recover from failure of PCI device "
"at location=%s driver=%s pci addr=%s \n"
"Please try reseating this device or replacing it.\n",
location, drv_str, pci_str);
perm_error:
eeh_slot_error_detail(frozen_pdn, EEH_LOG_PERM_FAILURE);
/* Notify all devices that they're about to go down. */
pci_walk_bus(frozen_bus, eeh_report_failure, NULL);
/* Shut down the device drivers for good. */
pcibios_remove_pci_devices(frozen_bus);
return NULL;
}
/* ---------- end of file ---------- */
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