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NTB: BWD Link Recovery 

The BWD NTB device will drop the link if an error is encountered on the
point-to-point PCI bridge.  The link will stay down until all errors are
cleared and the link is re-established.  On link down, check to see if
the error is detected, if so do the necessary housekeeping to try and
recover from the error and reestablish the link.

There is a potential race between the 2 NTB devices recovering at the
same time.  If the times are synchronized, the link will not recover and the
driver will be stuck in this loop forever.  Add a random interval to the
recovery time to prevent this race.

Signed-off-by: Jon Mason <jon.mason@intel.com>
This commit is contained in:
Jon Mason 2012-11-16 18:52:57 -07:00
parent 948d3a65b6
commit 113bf1c9f1
3 changed files with 127 additions and 3 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

110
drivers/ntb/ntb_hw.c
View File

@ -46,10 +46,12 @@
* Jon Mason <jon.mason@intel.com>
*/
#include <linux/debugfs.h>
#include <linux/delay.h>
#include <linux/init.h>
#include <linux/interrupt.h>
#include <linux/module.h>
#include <linux/pci.h>
#include <linux/random.h>
#include <linux/slab.h>
#include "ntb_hw.h"
#include "ntb_regs.h"
@ -84,6 +86,8 @@ enum {
static struct dentry *debugfs_dir;
#define BWD_LINK_RECOVERY_TIME 500
/* Translate memory window 0,1 to BAR 2,4 */
#define MW_TO_BAR(mw) (mw * NTB_MAX_NUM_MW + 2)
@ -425,6 +429,49 @@ void ntb_ring_sdb(struct ntb_device *ndev, unsigned int db)
(db * ndev->bits_per_vector), ndev->reg_ofs.sdb);
}
static void bwd_recover_link(struct ntb_device *ndev)
{
u32 status;
/* Driver resets the NTB ModPhy lanes - magic! */
writeb(0xe0, ndev->reg_base + BWD_MODPHY_PCSREG6);
writeb(0x40, ndev->reg_base + BWD_MODPHY_PCSREG4);
writeb(0x60, ndev->reg_base + BWD_MODPHY_PCSREG4);
writeb(0x60, ndev->reg_base + BWD_MODPHY_PCSREG6);
/* Driver waits 100ms to allow the NTB ModPhy to settle */
msleep(100);
/* Clear AER Errors, write to clear */
status = readl(ndev->reg_base + BWD_ERRCORSTS_OFFSET);
dev_dbg(&ndev->pdev->dev, "ERRCORSTS = %x\n", status);
status &= PCI_ERR_COR_REP_ROLL;
writel(status, ndev->reg_base + BWD_ERRCORSTS_OFFSET);
/* Clear unexpected electrical idle event in LTSSM, write to clear */
status = readl(ndev->reg_base + BWD_LTSSMERRSTS0_OFFSET);
dev_dbg(&ndev->pdev->dev, "LTSSMERRSTS0 = %x\n", status);
status |= BWD_LTSSMERRSTS0_UNEXPECTEDEI;
writel(status, ndev->reg_base + BWD_LTSSMERRSTS0_OFFSET);
/* Clear DeSkew Buffer error, write to clear */
status = readl(ndev->reg_base + BWD_DESKEWSTS_OFFSET);
dev_dbg(&ndev->pdev->dev, "DESKEWSTS = %x\n", status);
status |= BWD_DESKEWSTS_DBERR;
writel(status, ndev->reg_base + BWD_DESKEWSTS_OFFSET);
status = readl(ndev->reg_base + BWD_IBSTERRRCRVSTS0_OFFSET);
dev_dbg(&ndev->pdev->dev, "IBSTERRRCRVSTS0 = %x\n", status);
status &= BWD_IBIST_ERR_OFLOW;
writel(status, ndev->reg_base + BWD_IBSTERRRCRVSTS0_OFFSET);
/* Releases the NTB state machine to allow the link to retrain */
status = readl(ndev->reg_base + BWD_LTSSMSTATEJMP_OFFSET);
dev_dbg(&ndev->pdev->dev, "LTSSMSTATEJMP = %x\n", status);
status &= ~BWD_LTSSMSTATEJMP_FORCEDETECT;
writel(status, ndev->reg_base + BWD_LTSSMSTATEJMP_OFFSET);
}
static void ntb_link_event(struct ntb_device *ndev, int link_state)
{
unsigned int event;
@ -448,13 +495,16 @@ static void ntb_link_event(struct ntb_device *ndev, int link_state)
if (rc)
return;
}
ndev->link_width = (status & NTB_LINK_WIDTH_MASK) >> 4;
ndev->link_speed = (status & NTB_LINK_SPEED_MASK);
dev_info(&ndev->pdev->dev, "Link Width %d, Link Speed %d\n",
(status & NTB_LINK_WIDTH_MASK) >> 4,
(status & NTB_LINK_SPEED_MASK));
ndev->link_width, ndev->link_speed);
} else {
dev_info(&ndev->pdev->dev, "Link Down\n");
ndev->link_status = NTB_LINK_DOWN;
event = NTB_EVENT_HW_LINK_DOWN;
/* Don't modify link width/speed, we need it in link recovery */
}
/* notify the upper layer if we have an event change */
@ -494,6 +544,47 @@ static int ntb_link_status(struct ntb_device *ndev)
return 0;
}
static void bwd_link_recovery(struct work_struct *work)
{
struct ntb_device *ndev = container_of(work, struct ntb_device,
lr_timer.work);
u32 status32;
bwd_recover_link(ndev);
/* There is a potential race between the 2 NTB devices recovering at the
* same time. If the times are the same, the link will not recover and
* the driver will be stuck in this loop forever. Add a random interval
* to the recovery time to prevent this race.
*/
msleep(BWD_LINK_RECOVERY_TIME + prandom_u32() % BWD_LINK_RECOVERY_TIME);
status32 = readl(ndev->reg_base + BWD_LTSSMSTATEJMP_OFFSET);
if (status32 & BWD_LTSSMSTATEJMP_FORCEDETECT)
goto retry;
status32 = readl(ndev->reg_base + BWD_IBSTERRRCRVSTS0_OFFSET);
if (status32 & BWD_IBIST_ERR_OFLOW)
goto retry;
status32 = readl(ndev->reg_ofs.lnk_cntl);
if (!(status32 & BWD_CNTL_LINK_DOWN)) {
unsigned char speed, width;
u16 status16;
status16 = readw(ndev->reg_ofs.lnk_stat);
width = (status16 & NTB_LINK_WIDTH_MASK) >> 4;
speed = (status16 & NTB_LINK_SPEED_MASK);
if (ndev->link_width != width || ndev->link_speed != speed)
goto retry;
}
schedule_delayed_work(&ndev->hb_timer, NTB_HB_TIMEOUT);
return;
retry:
schedule_delayed_work(&ndev->lr_timer, NTB_HB_TIMEOUT);
}
/* BWD doesn't have link status interrupt, poll on that platform */
static void bwd_link_poll(struct work_struct *work)
{
@ -509,6 +600,16 @@ static void bwd_link_poll(struct work_struct *work)
if (rc)
dev_err(&ndev->pdev->dev,
"Error determining link status\n");
/* Check to see if a link error is the cause of the link down */
if (ndev->link_status == NTB_LINK_DOWN) {
u32 status32 = readl(ndev->reg_base +
BWD_LTSSMSTATEJMP_OFFSET);
if (status32 & BWD_LTSSMSTATEJMP_FORCEDETECT) {
schedule_delayed_work(&ndev->lr_timer, 0);
return;
}
}
}
schedule_delayed_work(&ndev->hb_timer, NTB_HB_TIMEOUT);
@ -703,6 +804,7 @@ static int ntb_bwd_setup(struct ntb_device *ndev)
/* Since bwd doesn't have a link interrupt, setup a poll timer */
INIT_DELAYED_WORK(&ndev->hb_timer, bwd_link_poll);
INIT_DELAYED_WORK(&ndev->lr_timer, bwd_link_recovery);
schedule_delayed_work(&ndev->hb_timer, NTB_HB_TIMEOUT);
return 0;
@ -743,8 +845,10 @@ static int ntb_device_setup(struct ntb_device *ndev)
static void ntb_device_free(struct ntb_device *ndev)
{
if (ndev->hw_type == BWD_HW)
if (ndev->hw_type == BWD_HW) {
cancel_delayed_work_sync(&ndev->hb_timer);
cancel_delayed_work_sync(&ndev->lr_timer);
}
}
static irqreturn_t bwd_callback_msix_irq(int irq, void *data)

5
drivers/ntb/ntb_hw.h
View File

@ -125,10 +125,15 @@ struct ntb_device {
unsigned char num_msix;
unsigned char bits_per_vector;
unsigned char max_cbs;
unsigned char link_width;
unsigned char link_speed;
unsigned char link_status;
struct delayed_work hb_timer;
unsigned long last_ts;
struct delayed_work lr_timer;
struct dentry *debugfs_dir;
};

15
drivers/ntb/ntb_regs.h
View File

@ -115,6 +115,7 @@
#define BWD_MBAR45_OFFSET 0xb020
#define BWD_DEVCTRL_OFFSET 0xb048
#define BWD_LINK_STATUS_OFFSET 0xb052
#define BWD_ERRCORSTS_OFFSET 0xb110
#define BWD_SBAR2XLAT_OFFSET 0x0008
#define BWD_SBAR4XLAT_OFFSET 0x0010
@ -132,6 +133,20 @@
#define BWD_B2B_SPADSEMA_OFFSET 0x80c0
#define BWD_B2B_STKYSPAD_OFFSET 0x80c4
#define BWD_MODPHY_PCSREG4 0x1c004
#define BWD_MODPHY_PCSREG6 0x1c006
#define BWD_IP_BASE 0xC000
#define BWD_DESKEWSTS_OFFSET (BWD_IP_BASE + 0x3024)
#define BWD_LTSSMERRSTS0_OFFSET (BWD_IP_BASE + 0x3180)
#define BWD_LTSSMSTATEJMP_OFFSET (BWD_IP_BASE + 0x3040)
#define BWD_IBSTERRRCRVSTS0_OFFSET (BWD_IP_BASE + 0x3324)
#define BWD_DESKEWSTS_DBERR (1 << 15)
#define BWD_LTSSMERRSTS0_UNEXPECTEDEI (1 << 20)
#define BWD_LTSSMSTATEJMP_FORCEDETECT (1 << 2)
#define BWD_IBIST_ERR_OFLOW 0x7FFF7FFF
#define NTB_CNTL_BAR23_SNOOP (1 << 2)
#define NTB_CNTL_BAR45_SNOOP (1 << 6)
#define BWD_CNTL_LINK_DOWN (1 << 16)