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
Родитель
948d3a65b6
Коммит
113bf1c9f1
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@ -46,10 +46,12 @@
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* Jon Mason <jon.mason@intel.com>
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*/
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#include <linux/debugfs.h>
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#include <linux/delay.h>
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#include <linux/init.h>
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#include <linux/interrupt.h>
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#include <linux/module.h>
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#include <linux/pci.h>
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#include <linux/random.h>
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#include <linux/slab.h>
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#include "ntb_hw.h"
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#include "ntb_regs.h"
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@ -84,6 +86,8 @@ enum {
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static struct dentry *debugfs_dir;
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#define BWD_LINK_RECOVERY_TIME 500
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/* Translate memory window 0,1 to BAR 2,4 */
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#define MW_TO_BAR(mw) (mw * NTB_MAX_NUM_MW + 2)
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@ -425,6 +429,49 @@ void ntb_ring_sdb(struct ntb_device *ndev, unsigned int db)
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(db * ndev->bits_per_vector), ndev->reg_ofs.sdb);
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}
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static void bwd_recover_link(struct ntb_device *ndev)
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{
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u32 status;
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/* Driver resets the NTB ModPhy lanes - magic! */
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writeb(0xe0, ndev->reg_base + BWD_MODPHY_PCSREG6);
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writeb(0x40, ndev->reg_base + BWD_MODPHY_PCSREG4);
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writeb(0x60, ndev->reg_base + BWD_MODPHY_PCSREG4);
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writeb(0x60, ndev->reg_base + BWD_MODPHY_PCSREG6);
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/* Driver waits 100ms to allow the NTB ModPhy to settle */
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msleep(100);
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/* Clear AER Errors, write to clear */
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status = readl(ndev->reg_base + BWD_ERRCORSTS_OFFSET);
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dev_dbg(&ndev->pdev->dev, "ERRCORSTS = %x\n", status);
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status &= PCI_ERR_COR_REP_ROLL;
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writel(status, ndev->reg_base + BWD_ERRCORSTS_OFFSET);
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/* Clear unexpected electrical idle event in LTSSM, write to clear */
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status = readl(ndev->reg_base + BWD_LTSSMERRSTS0_OFFSET);
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dev_dbg(&ndev->pdev->dev, "LTSSMERRSTS0 = %x\n", status);
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status |= BWD_LTSSMERRSTS0_UNEXPECTEDEI;
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writel(status, ndev->reg_base + BWD_LTSSMERRSTS0_OFFSET);
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/* Clear DeSkew Buffer error, write to clear */
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status = readl(ndev->reg_base + BWD_DESKEWSTS_OFFSET);
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dev_dbg(&ndev->pdev->dev, "DESKEWSTS = %x\n", status);
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status |= BWD_DESKEWSTS_DBERR;
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writel(status, ndev->reg_base + BWD_DESKEWSTS_OFFSET);
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status = readl(ndev->reg_base + BWD_IBSTERRRCRVSTS0_OFFSET);
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dev_dbg(&ndev->pdev->dev, "IBSTERRRCRVSTS0 = %x\n", status);
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status &= BWD_IBIST_ERR_OFLOW;
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writel(status, ndev->reg_base + BWD_IBSTERRRCRVSTS0_OFFSET);
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/* Releases the NTB state machine to allow the link to retrain */
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status = readl(ndev->reg_base + BWD_LTSSMSTATEJMP_OFFSET);
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dev_dbg(&ndev->pdev->dev, "LTSSMSTATEJMP = %x\n", status);
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status &= ~BWD_LTSSMSTATEJMP_FORCEDETECT;
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writel(status, ndev->reg_base + BWD_LTSSMSTATEJMP_OFFSET);
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}
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static void ntb_link_event(struct ntb_device *ndev, int link_state)
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{
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unsigned int event;
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@ -448,13 +495,16 @@ static void ntb_link_event(struct ntb_device *ndev, int link_state)
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if (rc)
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return;
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}
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ndev->link_width = (status & NTB_LINK_WIDTH_MASK) >> 4;
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ndev->link_speed = (status & NTB_LINK_SPEED_MASK);
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dev_info(&ndev->pdev->dev, "Link Width %d, Link Speed %d\n",
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(status & NTB_LINK_WIDTH_MASK) >> 4,
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(status & NTB_LINK_SPEED_MASK));
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ndev->link_width, ndev->link_speed);
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} else {
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dev_info(&ndev->pdev->dev, "Link Down\n");
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ndev->link_status = NTB_LINK_DOWN;
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event = NTB_EVENT_HW_LINK_DOWN;
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/* Don't modify link width/speed, we need it in link recovery */
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}
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/* notify the upper layer if we have an event change */
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@ -494,6 +544,47 @@ static int ntb_link_status(struct ntb_device *ndev)
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return 0;
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}
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static void bwd_link_recovery(struct work_struct *work)
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{
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struct ntb_device *ndev = container_of(work, struct ntb_device,
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lr_timer.work);
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u32 status32;
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bwd_recover_link(ndev);
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/* There is a potential race between the 2 NTB devices recovering at the
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* same time. If the times are the same, the link will not recover and
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* the driver will be stuck in this loop forever. Add a random interval
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* to the recovery time to prevent this race.
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*/
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msleep(BWD_LINK_RECOVERY_TIME + prandom_u32() % BWD_LINK_RECOVERY_TIME);
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status32 = readl(ndev->reg_base + BWD_LTSSMSTATEJMP_OFFSET);
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if (status32 & BWD_LTSSMSTATEJMP_FORCEDETECT)
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goto retry;
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status32 = readl(ndev->reg_base + BWD_IBSTERRRCRVSTS0_OFFSET);
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if (status32 & BWD_IBIST_ERR_OFLOW)
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goto retry;
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status32 = readl(ndev->reg_ofs.lnk_cntl);
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if (!(status32 & BWD_CNTL_LINK_DOWN)) {
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unsigned char speed, width;
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u16 status16;
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status16 = readw(ndev->reg_ofs.lnk_stat);
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width = (status16 & NTB_LINK_WIDTH_MASK) >> 4;
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speed = (status16 & NTB_LINK_SPEED_MASK);
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if (ndev->link_width != width || ndev->link_speed != speed)
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goto retry;
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}
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schedule_delayed_work(&ndev->hb_timer, NTB_HB_TIMEOUT);
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return;
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retry:
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schedule_delayed_work(&ndev->lr_timer, NTB_HB_TIMEOUT);
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}
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/* BWD doesn't have link status interrupt, poll on that platform */
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static void bwd_link_poll(struct work_struct *work)
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{
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@ -509,6 +600,16 @@ static void bwd_link_poll(struct work_struct *work)
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if (rc)
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dev_err(&ndev->pdev->dev,
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"Error determining link status\n");
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/* Check to see if a link error is the cause of the link down */
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if (ndev->link_status == NTB_LINK_DOWN) {
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u32 status32 = readl(ndev->reg_base +
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BWD_LTSSMSTATEJMP_OFFSET);
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if (status32 & BWD_LTSSMSTATEJMP_FORCEDETECT) {
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schedule_delayed_work(&ndev->lr_timer, 0);
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return;
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}
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}
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}
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schedule_delayed_work(&ndev->hb_timer, NTB_HB_TIMEOUT);
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@ -703,6 +804,7 @@ static int ntb_bwd_setup(struct ntb_device *ndev)
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/* Since bwd doesn't have a link interrupt, setup a poll timer */
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INIT_DELAYED_WORK(&ndev->hb_timer, bwd_link_poll);
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INIT_DELAYED_WORK(&ndev->lr_timer, bwd_link_recovery);
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schedule_delayed_work(&ndev->hb_timer, NTB_HB_TIMEOUT);
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return 0;
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@ -743,8 +845,10 @@ static int ntb_device_setup(struct ntb_device *ndev)
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static void ntb_device_free(struct ntb_device *ndev)
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{
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if (ndev->hw_type == BWD_HW)
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if (ndev->hw_type == BWD_HW) {
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cancel_delayed_work_sync(&ndev->hb_timer);
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cancel_delayed_work_sync(&ndev->lr_timer);
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}
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}
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static irqreturn_t bwd_callback_msix_irq(int irq, void *data)
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@ -125,10 +125,15 @@ struct ntb_device {
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unsigned char num_msix;
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unsigned char bits_per_vector;
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unsigned char max_cbs;
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unsigned char link_width;
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unsigned char link_speed;
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unsigned char link_status;
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struct delayed_work hb_timer;
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unsigned long last_ts;
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struct delayed_work lr_timer;
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struct dentry *debugfs_dir;
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};
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@ -115,6 +115,7 @@
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#define BWD_MBAR45_OFFSET 0xb020
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#define BWD_DEVCTRL_OFFSET 0xb048
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#define BWD_LINK_STATUS_OFFSET 0xb052
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#define BWD_ERRCORSTS_OFFSET 0xb110
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#define BWD_SBAR2XLAT_OFFSET 0x0008
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#define BWD_SBAR4XLAT_OFFSET 0x0010
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@ -132,6 +133,20 @@
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#define BWD_B2B_SPADSEMA_OFFSET 0x80c0
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#define BWD_B2B_STKYSPAD_OFFSET 0x80c4
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#define BWD_MODPHY_PCSREG4 0x1c004
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#define BWD_MODPHY_PCSREG6 0x1c006
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#define BWD_IP_BASE 0xC000
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#define BWD_DESKEWSTS_OFFSET (BWD_IP_BASE + 0x3024)
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#define BWD_LTSSMERRSTS0_OFFSET (BWD_IP_BASE + 0x3180)
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#define BWD_LTSSMSTATEJMP_OFFSET (BWD_IP_BASE + 0x3040)
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#define BWD_IBSTERRRCRVSTS0_OFFSET (BWD_IP_BASE + 0x3324)
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#define BWD_DESKEWSTS_DBERR (1 << 15)
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#define BWD_LTSSMERRSTS0_UNEXPECTEDEI (1 << 20)
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#define BWD_LTSSMSTATEJMP_FORCEDETECT (1 << 2)
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#define BWD_IBIST_ERR_OFLOW 0x7FFF7FFF
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#define NTB_CNTL_BAR23_SNOOP (1 << 2)
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#define NTB_CNTL_BAR45_SNOOP (1 << 6)
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#define BWD_CNTL_LINK_DOWN (1 << 16)
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