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[PATCH v3 04/16] switchtec: add link event notifier callback

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In order for the Switchtec NTB code to handle link change events we
create a notifier callback in the switchtec code which gets called
whenever an appropriate event interrupt occurs.

In order to preserve userspace's ability to follow these events,
we compare the event count with a stored copy from last time we
checked.

Signed-off-by: Logan Gunthorpe <logang@deltatee.com>
Reviewed-by: Stephen Bates <sbates@raithlin.com>
Reviewed-by: Kurt Schwemmer <kurt.schwemmer@microsemi.com>
Acked-by: Bjorn Helgaas <bhelgaas@google.com>
---
 drivers/pci/switch/switchtec.c | 51 ++++++++++++++++++++++++++++++++++++++++++
 include/linux/switchtec.h      |  4 ++++
 2 files changed, 55 insertions(+)

diff --git a/drivers/pci/switch/switchtec.c b/drivers/pci/switch/switchtec.c
index 39c9218d733f..807569e62bee 100644
--- a/drivers/pci/switch/switchtec.c
+++ b/drivers/pci/switch/switchtec.c
@@ -978,6 +978,49 @@ static const struct file_operations switchtec_fops = {
 	.compat_ioctl = switchtec_dev_ioctl,
 };
 
+static void link_event_work(struct work_struct *work)
+{
+	struct switchtec_dev *stdev;
+
+	stdev = container_of(work, struct switchtec_dev, link_event_work);
+
+	if (stdev->link_notifier)
+		stdev->link_notifier(stdev);
+}
+
+static void check_link_state_events(struct switchtec_dev *stdev)
+{
+	int idx;
+	u32 reg;
+	int count;
+	int occurred = 0;
+
+	for (idx = 0; idx < stdev->pff_csr_count; idx++) {
+		reg = ioread32(&stdev->mmio_pff_csr[idx].link_state_hdr);
+		dev_dbg(&stdev->dev, "link_state: %d->%08x\n", idx, reg);
+		count = (reg >> 5) & 0xFF;
+
+		if (count != stdev->link_event_count[idx]) {
+			occurred = 1;
+			stdev->link_event_count[idx] = count;
+		}
+	}
+
+	if (occurred)
+		schedule_work(&stdev->link_event_work);
+}
+
+static void enable_link_state_events(struct switchtec_dev *stdev)
+{
+	int idx;
+
+	for (idx = 0; idx < stdev->pff_csr_count; idx++) {
+		iowrite32(SWITCHTEC_EVENT_CLEAR |
+			  SWITCHTEC_EVENT_EN_IRQ,
+			  &stdev->mmio_pff_csr[idx].link_state_hdr);
+	}
+}
+
 static void stdev_release(struct device *dev)
 {
 	struct switchtec_dev *stdev = to_stdev(dev);
@@ -1030,6 +1073,7 @@ static struct switchtec_dev *stdev_create(struct pci_dev *pdev)
 	stdev->mrpc_busy = 0;
 	INIT_WORK(&stdev->mrpc_work, mrpc_event_work);
 	INIT_DELAYED_WORK(&stdev->mrpc_timeout, mrpc_timeout_work);
+	INIT_WORK(&stdev->link_event_work, link_event_work);
 	init_waitqueue_head(&stdev->event_wq);
 	atomic_set(&stdev->event_cnt, 0);
 
@@ -1073,6 +1117,9 @@ static int mask_event(struct switchtec_dev *stdev, int eid, int idx)
 	if (!(hdr & SWITCHTEC_EVENT_OCCURRED && hdr & SWITCHTEC_EVENT_EN_IRQ))
 		return 0;
 
+	if (eid == SWITCHTEC_IOCTL_EVENT_LINK_STATE)
+		return 0;
+
 	dev_dbg(&stdev->dev, "%s: %d %d %x\n", __func__, eid, idx, hdr);
 	hdr &= ~(SWITCHTEC_EVENT_EN_IRQ | SWITCHTEC_EVENT_OCCURRED);
 	iowrite32(hdr, hdr_reg);
@@ -1092,6 +1139,7 @@ static int mask_all_events(struct switchtec_dev *stdev, int eid)
 		for (idx = 0; idx < stdev->pff_csr_count; idx++) {
 			if (!stdev->pff_local[idx])
 				continue;
+
 			count += mask_event(stdev, eid, idx);
 		}
 	} else {
@@ -1116,6 +1164,8 @@ static irqreturn_t switchtec_event_isr(int irq, void *dev)
 		iowrite32(reg, &stdev->mmio_part_cfg->mrpc_comp_hdr);
 	}
 
+	check_link_state_events(stdev);
+
 	for (eid = 0; eid < SWITCHTEC_IOCTL_MAX_EVENTS; eid++)
 		event_count += mask_all_events(stdev, eid);
 
@@ -1242,6 +1292,7 @@ static int switchtec_pci_probe(struct pci_dev *pdev,
 	iowrite32(SWITCHTEC_EVENT_CLEAR |
 		  SWITCHTEC_EVENT_EN_IRQ,
 		  &stdev->mmio_part_cfg->mrpc_comp_hdr);
+	enable_link_state_events(stdev);
 
 	rc = cdev_device_add(&stdev->cdev, &stdev->dev);
 	if (rc)
diff --git a/include/linux/switchtec.h b/include/linux/switchtec.h
index 9c2be7631257..d8159944f013 100644
--- a/include/linux/switchtec.h
+++ b/include/linux/switchtec.h
@@ -353,6 +353,10 @@ struct switchtec_dev {
 
 	wait_queue_head_t event_wq;
 	atomic_t event_cnt;
+
+	struct work_struct link_event_work;
+	void (*link_notifier)(struct switchtec_dev *stdev);
+	u8 link_event_count[SWITCHTEC_MAX_PFF_CSR];
 };
 
 static inline struct switchtec_dev *to_stdev(struct device *dev)
-- 
2.11.0

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Thread

[PATCH v3 00/16] Switchtec NTB Support Logan Gunthorpe <logang@deltatee.com> - 2017-07-25 23:10 +0200
  [PATCH v3 15/16] switchtec_ntb: add memory window support Logan Gunthorpe <logang@deltatee.com> - 2017-07-25 23:10 +0200
  [PATCH v3 11/16] switchtec_ntb: add skeleton NTB driver Logan Gunthorpe <logang@deltatee.com> - 2017-07-25 23:10 +0200
  [PATCH v3 04/16] switchtec: add link event notifier callback Logan Gunthorpe <logang@deltatee.com> - 2017-07-25 23:10 +0200
  [PATCH v3 01/16] switchtec: move structure definitions into a common header Logan Gunthorpe <logang@deltatee.com> - 2017-07-25 23:10 +0200
  [PATCH v3 08/16] switchtec_ntb: introduce initial NTB driver Logan Gunthorpe <logang@deltatee.com> - 2017-07-25 23:10 +0200
  [PATCH v3 06/16] ntb: ensure ntb_mw_get_align() is only called when the link is up Logan Gunthorpe <logang@deltatee.com> - 2017-07-25 23:10 +0200
  RE: [PATCH v3 00/16] Switchtec NTB Support "Allen Hubbe" <Allen.Hubbe@dell.com> - 2017-07-26 15:20 +0200

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