NTB: Disable interrupts and poll under high load

[linux-drm-fsl-dcu.git] / drivers / ntb / ntb_hw.c

diff --git a/drivers/ntb/ntb_hw.c b/drivers/ntb/ntb_hw.c
index fa97948e66ad033116392c409325a76e2bd1c6bb..170e8e60cdb7fe3d47307d4b9146039e3af7f3a8 100644 (file)
--- a/drivers/ntb/ntb_hw.c
+++ b/drivers/ntb/ntb_hw.c
@@ -141,6 +141,24 @@ void ntb_unregister_event_callback(struct ntb_device *ndev)
        ndev->event_cb = NULL;
 }
 
+static void ntb_irq_work(unsigned long data)
+{
+       struct ntb_db_cb *db_cb = (struct ntb_db_cb *)data;
+       int rc;
+
+       rc = db_cb->callback(db_cb->data, db_cb->db_num);
+       if (rc)
+               tasklet_schedule(&db_cb->irq_work);
+       else {
+               struct ntb_device *ndev = db_cb->ndev;
+               unsigned long mask;
+
+               mask = readw(ndev->reg_ofs.ldb_mask);
+               clear_bit(db_cb->db_num * ndev->bits_per_vector, &mask);
+               writew(mask, ndev->reg_ofs.ldb_mask);
+       }
+}
+
 /**
  * ntb_register_db_callback() - register a callback for doorbell interrupt
  * @ndev: pointer to ntb_device instance
@@ -155,7 +173,7 @@ void ntb_unregister_event_callback(struct ntb_device *ndev)
  * RETURNS: An appropriate -ERRNO error value on error, or zero for success.
  */
 int ntb_register_db_callback(struct ntb_device *ndev, unsigned int idx,
-                            void *data, void (*func)(void *data, int db_num))
+                            void *data, int (*func)(void *data, int db_num))
 {
        unsigned long mask;
 
@@ -166,6 +184,10 @@ int ntb_register_db_callback(struct ntb_device *ndev, unsigned int idx,
 
        ndev->db_cb[idx].callback = func;
        ndev->db_cb[idx].data = data;
+       ndev->db_cb[idx].ndev = ndev;
+
+       tasklet_init(&ndev->db_cb[idx].irq_work, ntb_irq_work,
+                    (unsigned long) &ndev->db_cb[idx]);
 
        /* unmask interrupt */
        mask = readw(ndev->reg_ofs.ldb_mask);
@@ -194,6 +216,8 @@ void ntb_unregister_db_callback(struct ntb_device *ndev, unsigned int idx)
        set_bit(idx * ndev->bits_per_vector, &mask);
        writew(mask, ndev->reg_ofs.ldb_mask);
 
+       tasklet_disable(&ndev->db_cb[idx].irq_work);
+
        ndev->db_cb[idx].callback = NULL;
 }
 
@@ -689,6 +713,12 @@ static int ntb_xeon_setup(struct ntb_device *ndev)
                         */
                        writeq(ndev->mw[1].bar_sz + 0x1000, ndev->reg_base +
                               SNB_PBAR4LMT_OFFSET);
+                       /* HW errata on the Limit registers.  They can only be
+                        * written when the base register is 4GB aligned and
+                        * < 32bit.  This should already be the case based on the
+                        * driver defaults, but write the Limit registers first
+                        * just in case.
+                        */
                } else {
                        ndev->limits.max_mw = SNB_MAX_MW;
 
@@ -707,6 +737,12 @@ static int ntb_xeon_setup(struct ntb_device *ndev)
                         * something silly
                         */
                        writeq(0, ndev->reg_base + SNB_PBAR4LMT_OFFSET);
+                       /* HW errata on the Limit registers.  They can only be
+                        * written when the base register is 4GB aligned and
+                        * < 32bit.  This should already be the case based on the
+                        * driver defaults, but write the Limit registers first
+                        * just in case.
+                        */
                }
 
                /* The Xeon errata workaround requires setting SBAR Base
@@ -943,12 +979,16 @@ static irqreturn_t bwd_callback_msix_irq(int irq, void *data)
 {
        struct ntb_db_cb *db_cb = data;
        struct ntb_device *ndev = db_cb->ndev;
+       unsigned long mask;
 
        dev_dbg(&ndev->pdev->dev, "MSI-X irq %d received for DB %d\n", irq,
                db_cb->db_num);
 
-       if (db_cb->callback)
-               db_cb->callback(db_cb->data, db_cb->db_num);
+       mask = readw(ndev->reg_ofs.ldb_mask);
+       set_bit(db_cb->db_num * ndev->bits_per_vector, &mask);
+       writew(mask, ndev->reg_ofs.ldb_mask);
+
+       tasklet_schedule(&db_cb->irq_work);
 
        /* No need to check for the specific HB irq, any interrupt means
         * we're connected.
@@ -964,12 +1004,16 @@ static irqreturn_t xeon_callback_msix_irq(int irq, void *data)
 {
        struct ntb_db_cb *db_cb = data;
        struct ntb_device *ndev = db_cb->ndev;
+       unsigned long mask;
 
        dev_dbg(&ndev->pdev->dev, "MSI-X irq %d received for DB %d\n", irq,
                db_cb->db_num);
 
-       if (db_cb->callback)
-               db_cb->callback(db_cb->data, db_cb->db_num);
+       mask = readw(ndev->reg_ofs.ldb_mask);
+       set_bit(db_cb->db_num * ndev->bits_per_vector, &mask);
+       writew(mask, ndev->reg_ofs.ldb_mask);
+
+       tasklet_schedule(&db_cb->irq_work);
 
        /* On Sandybridge, there are 16 bits in the interrupt register
         * but only 4 vectors.  So, 5 bits are assigned to the first 3
@@ -1304,10 +1348,16 @@ static void ntb_hw_link_up(struct ntb_device *ndev)
 {
        if (ndev->conn_type == NTB_CONN_TRANSPARENT)
                ntb_link_event(ndev, NTB_LINK_UP);
-       else
+       else {
+               u32 ntb_cntl;
+
                /* Let's bring the NTB link up */
-               writel(NTB_CNTL_BAR23_SNOOP | NTB_CNTL_BAR45_SNOOP,
-                      ndev->reg_ofs.lnk_cntl);
+               ntb_cntl = readl(ndev->reg_ofs.lnk_cntl);
+               ntb_cntl &= ~(NTB_CNTL_LINK_DISABLE | NTB_CNTL_CFG_LOCK);
+               ntb_cntl |= NTB_CNTL_P2S_BAR23_SNOOP | NTB_CNTL_S2P_BAR23_SNOOP;
+               ntb_cntl |= NTB_CNTL_P2S_BAR45_SNOOP | NTB_CNTL_S2P_BAR45_SNOOP;
+               writel(ntb_cntl, ndev->reg_ofs.lnk_cntl);
+       }
 }
 
 static void ntb_hw_link_down(struct ntb_device *ndev)
@@ -1321,8 +1371,9 @@ static void ntb_hw_link_down(struct ntb_device *ndev)
 
        /* Bring NTB link down */
        ntb_cntl = readl(ndev->reg_ofs.lnk_cntl);
-       ntb_cntl &= ~(NTB_CNTL_BAR23_SNOOP | NTB_CNTL_BAR45_SNOOP);
-       ntb_cntl |= NTB_CNTL_LINK_DISABLE;
+       ntb_cntl &= ~(NTB_CNTL_P2S_BAR23_SNOOP | NTB_CNTL_S2P_BAR23_SNOOP);
+       ntb_cntl &= ~(NTB_CNTL_P2S_BAR45_SNOOP | NTB_CNTL_S2P_BAR45_SNOOP);
+       ntb_cntl |= NTB_CNTL_LINK_DISABLE | NTB_CNTL_CFG_LOCK;
        writel(ntb_cntl, ndev->reg_ofs.lnk_cntl);
 }