iv/linux
1
0
Fork 0
Code Issues Pull Requests Actions Packages Projects Releases Wiki Activity
linux/drivers/pci/hotplug/pciehp_ctrl.c
Rajat Jain c4f2f5e498 PCI: pciehp: Ensure very fast hotplug events are also processed 
Today, this is how all the hotplug and unplug events work:

Hotplug / Removal needs to be done
  => Set slot->state (protected by slot->lock) to either
    POWERON_STATE (for enabling) or POWEROFF_STATE (for disabling).
  => Submit the work item for pciehp_power_thread() to slot->wq.

Problem:
  There is a problem if the hotplug events can happen fast enough that
  they do not give SW enough time to add or remove the new devices.

  => Assume: Event for unplug comes (e.g. surprise removal). But
     before the pciehp_power_thread() work item was executed, the
     card was replaced by another card, causing surprise hotplug event.

  => What goes wrong:
    => The hot-removal event sets slot->state to POWEROFF_STATE, and
       schedules the pciehp_power_thread().
    => The hot-add event sets slot->state to POWERON_STATE, and
       schedules the pciehp_power_thread().
    => Now the pciehp_power_thread() is scheduled twice, and on both
       occasions it will find POWERON_STATE and will try to add the
       devices on the slot, and will fail complaining that the devices
       already exist.

  => Why this is a problem: If the device was replaced between the hot
     removal and hot-add, then we should unload the old driver and
     reload the new one. This does not happen today. The kernel or the
     driver is not even aware that the device was replaced.

     The problem is that the pciehp_power_thread() only looks at the
     slot->state which would only contain the *latest* state - not
     the actual event (add / remove) that was the intent of the IRQ
     handler who submitted the work.

What this patch does:

  => Hotplug events pass on an actual request (for addition or removal)
     to pciehp_power_thread() which is local to that work item
     submission.

  => pciehp_power_thread() does not need to look at slote->state and
     hence no locks needed in that.

  => Essentially this results in all the hotplug and unplug events
     "replayed" by pciehp_power_thread().

Signed-off-by: Rajat Jain <rajatxjain@gmail.com>
Signed-off-by: Rajat Jain <rajatjain@juniper.net>
Signed-off-by: Guenter Roeck <groeck@juniper.net>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
2014-02-11 16:13:01 -07:00

677 lines
16 KiB
C
Raw Blame History

/*
* PCI Express Hot Plug Controller Driver
*
* Copyright (C) 1995,2001 Compaq Computer Corporation
* Copyright (C) 2001 Greg Kroah-Hartman (greg@kroah.com)
* Copyright (C) 2001 IBM Corp.
* Copyright (C) 2003-2004 Intel Corporation
*
* 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 feedback to <greg@kroah.com>, <kristen.c.accardi@intel.com>
*
*/
#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/types.h>
#include <linux/slab.h>
#include <linux/pci.h>
#include "../pci.h"
#include "pciehp.h"
static void interrupt_event_handler(struct work_struct *work);
static int queue_interrupt_event(struct slot *p_slot, u32 event_type)
{
struct event_info *info;
info = kmalloc(sizeof(*info), GFP_ATOMIC);
if (!info)
return -ENOMEM;
info->event_type = event_type;
info->p_slot = p_slot;
INIT_WORK(&info->work, interrupt_event_handler);
queue_work(p_slot->wq, &info->work);
return 0;
}
u8 pciehp_handle_attention_button(struct slot *p_slot)
{
u32 event_type;
struct controller *ctrl = p_slot->ctrl;
/* Attention Button Change */
ctrl_dbg(ctrl, "Attention button interrupt received\n");
/*
* Button pressed - See if need to TAKE ACTION!!!
*/
ctrl_info(ctrl, "Button pressed on Slot(%s)\n", slot_name(p_slot));
event_type = INT_BUTTON_PRESS;
queue_interrupt_event(p_slot, event_type);
return 0;
}
u8 pciehp_handle_switch_change(struct slot *p_slot)
{
u8 getstatus;
u32 event_type;
struct controller *ctrl = p_slot->ctrl;
/* Switch Change */
ctrl_dbg(ctrl, "Switch interrupt received\n");
pciehp_get_latch_status(p_slot, &getstatus);
if (getstatus) {
/*
* Switch opened
*/
ctrl_info(ctrl, "Latch open on Slot(%s)\n", slot_name(p_slot));
event_type = INT_SWITCH_OPEN;
} else {
/*
* Switch closed
*/
ctrl_info(ctrl, "Latch close on Slot(%s)\n", slot_name(p_slot));
event_type = INT_SWITCH_CLOSE;
}
queue_interrupt_event(p_slot, event_type);
return 1;
}
u8 pciehp_handle_presence_change(struct slot *p_slot)
{
u32 event_type;
u8 presence_save;
struct controller *ctrl = p_slot->ctrl;
/* Presence Change */
ctrl_dbg(ctrl, "Presence/Notify input change\n");
/* Switch is open, assume a presence change
* Save the presence state
*/
pciehp_get_adapter_status(p_slot, &presence_save);
if (presence_save) {
/*
* Card Present
*/
ctrl_info(ctrl, "Card present on Slot(%s)\n", slot_name(p_slot));
event_type = INT_PRESENCE_ON;
} else {
/*
* Not Present
*/
ctrl_info(ctrl, "Card not present on Slot(%s)\n",
slot_name(p_slot));
event_type = INT_PRESENCE_OFF;
}
queue_interrupt_event(p_slot, event_type);
return 1;
}
u8 pciehp_handle_power_fault(struct slot *p_slot)
{
u32 event_type;
struct controller *ctrl = p_slot->ctrl;
/* power fault */
ctrl_dbg(ctrl, "Power fault interrupt received\n");
ctrl_err(ctrl, "Power fault on slot %s\n", slot_name(p_slot));
event_type = INT_POWER_FAULT;
ctrl_info(ctrl, "Power fault bit %x set\n", 0);
queue_interrupt_event(p_slot, event_type);
return 1;
}
void pciehp_handle_linkstate_change(struct slot *p_slot)
{
u32 event_type;
struct controller *ctrl = p_slot->ctrl;
/* Link Status Change */
ctrl_dbg(ctrl, "Data Link Layer State change\n");
if (pciehp_check_link_active(ctrl)) {
ctrl_info(ctrl, "slot(%s): Link Up event\n",
slot_name(p_slot));
event_type = INT_LINK_UP;
} else {
ctrl_info(ctrl, "slot(%s): Link Down event\n",
slot_name(p_slot));
event_type = INT_LINK_DOWN;
}
queue_interrupt_event(p_slot, event_type);
}
/* The following routines constitute the bulk of the
hotplug controller logic
*/
static void set_slot_off(struct controller *ctrl, struct slot * pslot)
{
/* turn off slot, turn on Amber LED, turn off Green LED if supported*/
if (POWER_CTRL(ctrl)) {
pciehp_power_off_slot(pslot);
/*
* After turning power off, we must wait for at least 1 second
* before taking any action that relies on power having been
* removed from the slot/adapter.
*/
msleep(1000);
}
pciehp_green_led_off(pslot);
pciehp_set_attention_status(pslot, 1);
}
/**
* board_added - Called after a board has been added to the system.
* @p_slot: &slot where board is added
*
* Turns power on for the board.
* Configures board.
*/
static int board_added(struct slot *p_slot)
{
int retval = 0;
struct controller *ctrl = p_slot->ctrl;
struct pci_bus *parent = ctrl->pcie->port->subordinate;
if (POWER_CTRL(ctrl)) {
/* Power on slot */
retval = pciehp_power_on_slot(p_slot);
if (retval)
return retval;
}
pciehp_green_led_blink(p_slot);
/* Check link training status */
retval = pciehp_check_link_status(ctrl);
if (retval) {
ctrl_err(ctrl, "Failed to check link status\n");
goto err_exit;
}
/* Check for a power fault */
if (ctrl->power_fault_detected || pciehp_query_power_fault(p_slot)) {
ctrl_err(ctrl, "Power fault on slot %s\n", slot_name(p_slot));
retval = -EIO;
goto err_exit;
}
retval = pciehp_configure_device(p_slot);
if (retval) {
ctrl_err(ctrl, "Cannot add device at %04x:%02x:00\n",
pci_domain_nr(parent), parent->number);
goto err_exit;
}
pciehp_green_led_on(p_slot);
return 0;
err_exit:
set_slot_off(ctrl, p_slot);
return retval;
}
/**
* remove_board - Turns off slot and LEDs
* @p_slot: slot where board is being removed
*/
static int remove_board(struct slot *p_slot)
{
int retval;
struct controller *ctrl = p_slot->ctrl;
retval = pciehp_unconfigure_device(p_slot);
if (retval)
return retval;
if (POWER_CTRL(ctrl)) {
pciehp_power_off_slot(p_slot);
/*
* After turning power off, we must wait for at least 1 second
* before taking any action that relies on power having been
* removed from the slot/adapter.
*/
msleep(1000);
}
/* turn off Green LED */
pciehp_green_led_off(p_slot);
return 0;
}
struct power_work_info {
struct slot *p_slot;
struct work_struct work;
unsigned int req;
#define DISABLE_REQ 0
#define ENABLE_REQ 1
};
/**
* pciehp_power_thread - handle pushbutton events
* @work: &struct work_struct describing work to be done
*
* Scheduled procedure to handle blocking stuff for the pushbuttons.
* Handles all pending events and exits.
*/
static void pciehp_power_thread(struct work_struct *work)
{
struct power_work_info *info =
container_of(work, struct power_work_info, work);
struct slot *p_slot = info->p_slot;
switch (info->req) {
case DISABLE_REQ:
ctrl_dbg(p_slot->ctrl,
"Disabling domain:bus:device=%04x:%02x:00\n",
pci_domain_nr(p_slot->ctrl->pcie->port->subordinate),
p_slot->ctrl->pcie->port->subordinate->number);
pciehp_disable_slot(p_slot);
mutex_lock(&p_slot->lock);
p_slot->state = STATIC_STATE;
mutex_unlock(&p_slot->lock);
break;
case ENABLE_REQ:
ctrl_dbg(p_slot->ctrl,
"Enabling domain:bus:device=%04x:%02x:00\n",
pci_domain_nr(p_slot->ctrl->pcie->port->subordinate),
p_slot->ctrl->pcie->port->subordinate->number);
if (pciehp_enable_slot(p_slot))
pciehp_green_led_off(p_slot);
mutex_lock(&p_slot->lock);
p_slot->state = STATIC_STATE;
mutex_unlock(&p_slot->lock);
break;
default:
break;
}
kfree(info);
}
void pciehp_queue_pushbutton_work(struct work_struct *work)
{
struct slot *p_slot = container_of(work, struct slot, work.work);
struct power_work_info *info;
info = kmalloc(sizeof(*info), GFP_KERNEL);
if (!info) {
ctrl_err(p_slot->ctrl, "%s: Cannot allocate memory\n",
__func__);
return;
}
info->p_slot = p_slot;
INIT_WORK(&info->work, pciehp_power_thread);
mutex_lock(&p_slot->lock);
switch (p_slot->state) {
case BLINKINGOFF_STATE:
p_slot->state = POWEROFF_STATE;
info->req = DISABLE_REQ;
break;
case BLINKINGON_STATE:
p_slot->state = POWERON_STATE;
info->req = ENABLE_REQ;
break;
default:
kfree(info);
goto out;
}
queue_work(p_slot->wq, &info->work);
out:
mutex_unlock(&p_slot->lock);
}
/*
* Note: This function must be called with slot->lock held
*/
static void handle_button_press_event(struct slot *p_slot)
{
struct controller *ctrl = p_slot->ctrl;
u8 getstatus;
switch (p_slot->state) {
case STATIC_STATE:
pciehp_get_power_status(p_slot, &getstatus);
if (getstatus) {
p_slot->state = BLINKINGOFF_STATE;
ctrl_info(ctrl,
"PCI slot #%s - powering off due to button "
"press.\n", slot_name(p_slot));
} else {
p_slot->state = BLINKINGON_STATE;
ctrl_info(ctrl,
"PCI slot #%s - powering on due to button "
"press.\n", slot_name(p_slot));
}
/* blink green LED and turn off amber */
pciehp_green_led_blink(p_slot);
pciehp_set_attention_status(p_slot, 0);
queue_delayed_work(p_slot->wq, &p_slot->work, 5*HZ);
break;
case BLINKINGOFF_STATE:
case BLINKINGON_STATE:
/*
* Cancel if we are still blinking; this means that we
* press the attention again before the 5 sec. limit
* expires to cancel hot-add or hot-remove
*/
ctrl_info(ctrl, "Button cancel on Slot(%s)\n", slot_name(p_slot));
cancel_delayed_work(&p_slot->work);
if (p_slot->state == BLINKINGOFF_STATE) {
pciehp_green_led_on(p_slot);
} else {
pciehp_green_led_off(p_slot);
}
pciehp_set_attention_status(p_slot, 0);
ctrl_info(ctrl, "PCI slot #%s - action canceled "
"due to button press\n", slot_name(p_slot));
p_slot->state = STATIC_STATE;
break;
case POWEROFF_STATE:
case POWERON_STATE:
/*
* Ignore if the slot is on power-on or power-off state;
* this means that the previous attention button action
* to hot-add or hot-remove is undergoing
*/
ctrl_info(ctrl, "Button ignore on Slot(%s)\n", slot_name(p_slot));
break;
default:
ctrl_warn(ctrl, "Not a valid state\n");
break;
}
}
/*
* Note: This function must be called with slot->lock held
*/
static void handle_surprise_event(struct slot *p_slot)
{
u8 getstatus;
struct power_work_info *info;
info = kmalloc(sizeof(*info), GFP_KERNEL);
if (!info) {
ctrl_err(p_slot->ctrl, "%s: Cannot allocate memory\n",
__func__);
return;
}
info->p_slot = p_slot;
INIT_WORK(&info->work, pciehp_power_thread);
pciehp_get_adapter_status(p_slot, &getstatus);
if (!getstatus) {
p_slot->state = POWEROFF_STATE;
info->req = DISABLE_REQ;
} else {
p_slot->state = POWERON_STATE;
info->req = ENABLE_REQ;
}
queue_work(p_slot->wq, &info->work);
}
/*
* Note: This function must be called with slot->lock held
*/
static void handle_link_event(struct slot *p_slot, u32 event)
{
struct controller *ctrl = p_slot->ctrl;
struct power_work_info *info;
info = kmalloc(sizeof(*info), GFP_KERNEL);
if (!info) {
ctrl_err(p_slot->ctrl, "%s: Cannot allocate memory\n",
__func__);
return;
}
info->p_slot = p_slot;
info->req = event == INT_LINK_UP ? ENABLE_REQ : DISABLE_REQ;
INIT_WORK(&info->work, pciehp_power_thread);
switch (p_slot->state) {
case BLINKINGON_STATE:
case BLINKINGOFF_STATE:
cancel_delayed_work(&p_slot->work);
/* Fall through */
case STATIC_STATE:
p_slot->state = event == INT_LINK_UP ?
POWERON_STATE : POWEROFF_STATE;
queue_work(p_slot->wq, &info->work);
break;
case POWERON_STATE:
if (event == INT_LINK_UP) {
ctrl_info(ctrl,
"Link Up event ignored on slot(%s): already powering on\n",
slot_name(p_slot));
kfree(info);
} else {
ctrl_info(ctrl,
"Link Down event queued on slot(%s): currently getting powered on\n",
slot_name(p_slot));
p_slot->state = POWEROFF_STATE;
queue_work(p_slot->wq, &info->work);
}
break;
case POWEROFF_STATE:
if (event == INT_LINK_UP) {
ctrl_info(ctrl,
"Link Up event queued on slot(%s): currently getting powered off\n",
slot_name(p_slot));
p_slot->state = POWERON_STATE;
queue_work(p_slot->wq, &info->work);
} else {
ctrl_info(ctrl,
"Link Down event ignored on slot(%s): already powering off\n",
slot_name(p_slot));
kfree(info);
}
break;
default:
ctrl_err(ctrl, "Not a valid state on slot(%s)\n",
slot_name(p_slot));
kfree(info);
break;
}
}
static void interrupt_event_handler(struct work_struct *work)
{
struct event_info *info = container_of(work, struct event_info, work);
struct slot *p_slot = info->p_slot;
struct controller *ctrl = p_slot->ctrl;
mutex_lock(&p_slot->lock);
switch (info->event_type) {
case INT_BUTTON_PRESS:
handle_button_press_event(p_slot);
break;
case INT_POWER_FAULT:
if (!POWER_CTRL(ctrl))
break;
pciehp_set_attention_status(p_slot, 1);
pciehp_green_led_off(p_slot);
break;
case INT_PRESENCE_ON:
case INT_PRESENCE_OFF:
if (!HP_SUPR_RM(ctrl))
break;
ctrl_dbg(ctrl, "Surprise Removal\n");
handle_surprise_event(p_slot);
break;
case INT_LINK_UP:
case INT_LINK_DOWN:
handle_link_event(p_slot, info->event_type);
break;
default:
break;
}
mutex_unlock(&p_slot->lock);
kfree(info);
}
int pciehp_enable_slot(struct slot *p_slot)
{
u8 getstatus = 0;
int rc;
struct controller *ctrl = p_slot->ctrl;
pciehp_get_adapter_status(p_slot, &getstatus);
if (!getstatus) {
ctrl_info(ctrl, "No adapter on slot(%s)\n", slot_name(p_slot));
return -ENODEV;
}
if (MRL_SENS(p_slot->ctrl)) {
pciehp_get_latch_status(p_slot, &getstatus);
if (getstatus) {
ctrl_info(ctrl, "Latch open on slot(%s)\n",
slot_name(p_slot));
return -ENODEV;
}
}
if (POWER_CTRL(p_slot->ctrl)) {
pciehp_get_power_status(p_slot, &getstatus);
if (getstatus) {
ctrl_info(ctrl, "Already enabled on slot(%s)\n",
slot_name(p_slot));
return -EINVAL;
}
}
pciehp_get_latch_status(p_slot, &getstatus);
rc = board_added(p_slot);
if (rc) {
pciehp_get_latch_status(p_slot, &getstatus);
}
return rc;
}
int pciehp_disable_slot(struct slot *p_slot)
{
u8 getstatus = 0;
struct controller *ctrl = p_slot->ctrl;
if (!p_slot->ctrl)
return 1;
if (POWER_CTRL(p_slot->ctrl)) {
pciehp_get_power_status(p_slot, &getstatus);
if (!getstatus) {
ctrl_info(ctrl, "Already disabled on slot(%s)\n",
slot_name(p_slot));
return -EINVAL;
}
}
return remove_board(p_slot);
}
int pciehp_sysfs_enable_slot(struct slot *p_slot)
{
int retval = -ENODEV;
struct controller *ctrl = p_slot->ctrl;
mutex_lock(&p_slot->lock);
switch (p_slot->state) {
case BLINKINGON_STATE:
cancel_delayed_work(&p_slot->work);
case STATIC_STATE:
p_slot->state = POWERON_STATE;
mutex_unlock(&p_slot->lock);
retval = pciehp_enable_slot(p_slot);
mutex_lock(&p_slot->lock);
p_slot->state = STATIC_STATE;
break;
case POWERON_STATE:
ctrl_info(ctrl, "Slot %s is already in powering on state\n",
slot_name(p_slot));
break;
case BLINKINGOFF_STATE:
case POWEROFF_STATE:
ctrl_info(ctrl, "Already enabled on slot %s\n",
slot_name(p_slot));
break;
default:
ctrl_err(ctrl, "Not a valid state on slot %s\n",
slot_name(p_slot));
break;
}
mutex_unlock(&p_slot->lock);
return retval;
}
int pciehp_sysfs_disable_slot(struct slot *p_slot)
{
int retval = -ENODEV;
struct controller *ctrl = p_slot->ctrl;
mutex_lock(&p_slot->lock);
switch (p_slot->state) {
case BLINKINGOFF_STATE:
cancel_delayed_work(&p_slot->work);
case STATIC_STATE:
p_slot->state = POWEROFF_STATE;
mutex_unlock(&p_slot->lock);
retval = pciehp_disable_slot(p_slot);
mutex_lock(&p_slot->lock);
p_slot->state = STATIC_STATE;
break;
case POWEROFF_STATE:
ctrl_info(ctrl, "Slot %s is already in powering off state\n",
slot_name(p_slot));
break;
case BLINKINGON_STATE:
case POWERON_STATE:
ctrl_info(ctrl, "Already disabled on slot %s\n",
slot_name(p_slot));
break;
default:
ctrl_err(ctrl, "Not a valid state on slot %s\n",
slot_name(p_slot));
break;
}
mutex_unlock(&p_slot->lock);
return retval;
}
Reference in New Issue View Git Blame Copy Permalink