[PATCH 3/3] vme: change bus error handling scheme

[Dmitry Kalinkin]

The current VME bus error handler adds errors to the bridge error list.
vme_master_{read,write} then traverses that list to look for relevant
errors.

Such scheme didn't work well for accesses going through vme_master_mmap
because they would also allocate a vme_bus_error, but have no way to do
vme_clear_errors call to free that memory.

This changes the error handling process to be other way around: now
vme_master_{read,write} defines a window in VME address space that will
catch possible errors.  VME bus error interrupt only traverses these
windows and marks those that had errors in them.

Signed-off-by: Dmitry Kalinkin <dmitry.kalinkin@xxxxxxxxx>
Cc: Igor Alekseev <igor.alekseev@xxxxxxx>
---
 drivers/vme/bridges/vme_ca91cx42.c |  3 +-
 drivers/vme/bridges/vme_tsi148.c   | 83 +++++++++++++++++-----------------
 drivers/vme/vme.c                  | 92 ++++++++++++++------------------------
 drivers/vme/vme_bridge.h           | 23 ++++++----
 4 files changed, 91 insertions(+), 110 deletions(-)

diff --git a/drivers/vme/bridges/vme_ca91cx42.c b/drivers/vme/bridges/vme_ca91cx42.c
index f692efc..834883d 100644
--- a/drivers/vme/bridges/vme_ca91cx42.c
+++ b/drivers/vme/bridges/vme_ca91cx42.c
@@ -204,8 +204,7 @@ static int ca91cx42_irq_init(struct vme_bridge *ca91cx42_bridge)
 	/* Need pdev */
 	pdev = container_of(ca91cx42_bridge->parent, struct pci_dev, dev);
 
-	/* Initialise list for VME bus errors */
-	INIT_LIST_HEAD(&ca91cx42_bridge->vme_errors);
+	INIT_LIST_HEAD(&ca91cx42_bridge->vme_error_handlers);
 
 	mutex_init(&ca91cx42_bridge->irq_mtx);
 
diff --git a/drivers/vme/bridges/vme_tsi148.c b/drivers/vme/bridges/vme_tsi148.c
index 76ccfae..b0132e0 100644
--- a/drivers/vme/bridges/vme_tsi148.c
+++ b/drivers/vme/bridges/vme_tsi148.c
@@ -314,8 +314,7 @@ static int tsi148_irq_init(struct vme_bridge *tsi148_bridge)
 
 	bridge = tsi148_bridge->driver_priv;
 
-	/* Initialise list for VME bus errors */
-	INIT_LIST_HEAD(&tsi148_bridge->vme_errors);
+	INIT_LIST_HEAD(&tsi148_bridge->vme_error_handlers);
 
 	mutex_init(&tsi148_bridge->irq_mtx);
 
@@ -1187,7 +1186,7 @@ static ssize_t tsi148_master_read(struct vme_master_resource *image, void *buf,
 	int retval, enabled;
 	unsigned long long vme_base, size;
 	u32 aspace, cycle, dwidth;
-	struct vme_bus_error *vme_err = NULL;
+	struct vme_error_handler *handler;
 	struct vme_bridge *tsi148_bridge;
 	void __iomem *addr = image->kern_base + offset;
 	unsigned int done = 0;
@@ -1197,6 +1196,17 @@ static ssize_t tsi148_master_read(struct vme_master_resource *image, void *buf,
 
 	spin_lock(&image->lock);
 
+	if (err_chk) {
+		__tsi148_master_get(image, &enabled, &vme_base, &size, &aspace,
+				    &cycle, &dwidth);
+		handler = vme_register_error_handler(tsi148_bridge, aspace,
+						     vme_base + offset, count);
+		if (!handler) {
+			spin_unlock(&image->lock);
+			return -ENOMEM;
+		}
+	}
+
 	/* The following code handles VME address alignment. We cannot use
 	 * memcpy_xxx here because it may cut data transfers in to 8-bit
 	 * cycles when D16 or D32 cycles are required on the VME bus.
@@ -1240,24 +1250,16 @@ static ssize_t tsi148_master_read(struct vme_master_resource *image, void *buf,
 out:
 	retval = count;
 
-	if (!err_chk)
-		goto skip_chk;
-
-	__tsi148_master_get(image, &enabled, &vme_base, &size, &aspace, &cycle,
-		&dwidth);
-
-	vme_err = vme_find_error(tsi148_bridge, aspace, vme_base + offset,
-		count);
-	if (vme_err != NULL) {
-		dev_err(image->parent->parent, "First VME read error detected "
-			"an at address 0x%llx\n", vme_err->address);
-		retval = vme_err->address - (vme_base + offset);
-		/* Clear down save errors in this address range */
-		vme_clear_errors(tsi148_bridge, aspace, vme_base + offset,
-			count);
+	if (err_chk) {
+		if (handler->num_errors) {
+			dev_err(image->parent->parent,
+				"First VME read error detected an at address 0x%llx\n",
+				handler->first_error);
+			retval = handler->first_error - (vme_base + offset);
+		}
+		vme_unregister_error_handler(handler);
 	}
 
-skip_chk:
 	spin_unlock(&image->lock);
 
 	return retval;
@@ -1274,7 +1276,7 @@ static ssize_t tsi148_master_write(struct vme_master_resource *image, void *buf,
 	unsigned int done = 0;
 	unsigned int count32;
 
-	struct vme_bus_error *vme_err = NULL;
+	struct vme_error_handler *handler;
 	struct vme_bridge *tsi148_bridge;
 	struct tsi148_driver *bridge;
 
@@ -1284,6 +1286,17 @@ static ssize_t tsi148_master_write(struct vme_master_resource *image, void *buf,
 
 	spin_lock(&image->lock);
 
+	if (err_chk) {
+		__tsi148_master_get(image, &enabled, &vme_base, &size, &aspace,
+				    &cycle, &dwidth);
+		handler = vme_register_error_handler(tsi148_bridge, aspace,
+						     vme_base + offset, count);
+		if (!handler) {
+			spin_unlock(&image->lock);
+			return -ENOMEM;
+		}
+	}
+
 	/* Here we apply for the same strategy we do in master_read
 	 * function in order to assure the correct cycles.
 	 */
@@ -1333,30 +1346,18 @@ out:
 	 * We check for saved errors in the written address range/space.
 	 */
 
-	if (!err_chk)
-		goto skip_chk;
-
-	/*
-	 * Get window info first, to maximise the time that the buffers may
-	 * fluch on their own
-	 */
-	__tsi148_master_get(image, &enabled, &vme_base, &size, &aspace, &cycle,
-		&dwidth);
-
-	ioread16(bridge->flush_image->kern_base + 0x7F000);
+	if (err_chk) {
+		ioread16(bridge->flush_image->kern_base + 0x7F000);
 
-	vme_err = vme_find_error(tsi148_bridge, aspace, vme_base + offset,
-		count);
-	if (vme_err != NULL) {
-		dev_warn(tsi148_bridge->parent, "First VME write error detected"
-			" an at address 0x%llx\n", vme_err->address);
-		retval = vme_err->address - (vme_base + offset);
-		/* Clear down save errors in this address range */
-		vme_clear_errors(tsi148_bridge, aspace, vme_base + offset,
-			count);
+		if (handler->num_errors) {
+			dev_warn(tsi148_bridge->parent,
+				 "First VME write error detected an at address 0x%llx\n",
+				 handler->first_error);
+			retval = handler->first_error - (vme_base + offset);
+		}
+		vme_unregister_error_handler(handler);
 	}
 
-skip_chk:
 	spin_unlock(&image->lock);
 
 	return retval;
diff --git a/drivers/vme/vme.c b/drivers/vme/vme.c
index 2b79cd2..7a10d92 100644
--- a/drivers/vme/vme.c
+++ b/drivers/vme/vme.c
@@ -1026,76 +1026,52 @@ EXPORT_SYMBOL(vme_dma_free);
 void vme_bus_error_handler(struct vme_bridge *bridge,
 			   unsigned long long address, int am)
 {
-	struct vme_bus_error *error;
-
-	error = kmalloc(sizeof(struct vme_bus_error), GFP_ATOMIC);
-	if (error) {
-		error->aspace = vme_get_aspace(am);
-		error->address = address;
-		list_add_tail(&error->list, &bridge->vme_errors);
-	} else {
-		dev_err(bridge->parent,
-			"Unable to alloc memory for VMEbus Error reporting\n");
+	struct list_head *handler_pos = NULL;
+	struct vme_error_handler *handler;
+	u32 aspace = vme_get_aspace(am);
+
+	list_for_each(handler_pos, &bridge->vme_error_handlers) {
+		handler = list_entry(handler_pos, struct vme_error_handler,
+				     list);
+		if ((aspace == handler->aspace) &&
+		    (address >= handler->start) &&
+		    (address < handler->end)) {
+			if (!handler->num_errors)
+				handler->first_error = address;
+			if (handler->num_errors != UINT_MAX)
+				handler->num_errors++;
+		}
 	}
 }
 EXPORT_SYMBOL(vme_bus_error_handler);
 
-/*
- * Find the first error in this address range
- */
-struct vme_bus_error *vme_find_error(struct vme_bridge *bridge, u32 aspace,
-				     unsigned long long address, size_t count)
+struct vme_error_handler *vme_register_error_handler(
+	struct vme_bridge *bridge, u32 aspace,
+	unsigned long long address, size_t len)
 {
-	struct list_head *err_pos;
-	struct vme_bus_error *vme_err, *valid = NULL;
-	unsigned long long bound;
-
-	bound = address + count;
+	struct vme_error_handler *handler;
 
-	err_pos = NULL;
-	/* Iterate through errors */
-	list_for_each(err_pos, &bridge->vme_errors) {
-		vme_err = list_entry(err_pos, struct vme_bus_error, list);
-		if ((vme_err->aspace == aspace) &&
-		    (vme_err->address >= address) &&
-		    (vme_err->address < bound)) {
+	handler = kmalloc(sizeof(*handler), GFP_KERNEL);
+	if (!handler)
+		return NULL;
 
-			valid = vme_err;
-			break;
-		}
-	}
+	handler->aspace = aspace;
+	handler->start = address;
+	handler->end = address + len;
+	handler->num_errors = 0;
+	handler->first_error = 0;
+	list_add_tail(&handler->list, &bridge->vme_error_handlers);
 
-	return valid;
+	return handler;
 }
-EXPORT_SYMBOL(vme_find_error);
+EXPORT_SYMBOL(vme_register_error_handler);
 
-/*
- * Clear errors in the provided address range.
- */
-void vme_clear_errors(struct vme_bridge *bridge, u32 aspace,
-		      unsigned long long address, size_t count)
+void vme_unregister_error_handler(struct vme_error_handler *handler)
 {
-	struct list_head *err_pos, *temp;
-	struct vme_bus_error *vme_err;
-	unsigned long long bound;
-
-	bound = address + count;
-
-	err_pos = NULL;
-	/* Iterate through errors */
-	list_for_each_safe(err_pos, temp, &bridge->vme_errors) {
-		vme_err = list_entry(err_pos, struct vme_bus_error, list);
-
-		if ((vme_err->aspace == aspace) &&
-		    (vme_err->address >= address) &&
-		    (vme_err->address < bound)) {
-
-			list_del(err_pos);
-			kfree(vme_err);
-		}
-	}
+	list_del(&handler->list);
+	kfree(handler);
 }
-EXPORT_SYMBOL(vme_clear_errors);
+EXPORT_SYMBOL(vme_unregister_error_handler);
 
 void vme_irq_handler(struct vme_bridge *bridge, int level, int statid)
 {
diff --git a/drivers/vme/vme_bridge.h b/drivers/vme/vme_bridge.h
index 92fbe18..397578a 100644
--- a/drivers/vme/vme_bridge.h
+++ b/drivers/vme/vme_bridge.h
@@ -75,10 +75,13 @@ struct vme_lm_resource {
 	int monitors;
 };
 
-struct vme_bus_error {
+struct vme_error_handler {
 	struct list_head list;
-	u32 aspace;
-	unsigned long long address;
+	unsigned long long start;	/* Beginning of error window */
+	unsigned long long end;		/* End of error window */
+	unsigned long long first_error;	/* Address of the first error */
+	u32 aspace;			/* Address space of error window*/
+	unsigned num_errors;		/* Number of errors */
 };
 
 struct vme_callback {
@@ -106,8 +109,10 @@ struct vme_bridge {
 	struct list_head dma_resources;
 	struct list_head lm_resources;
 
-	struct list_head vme_errors;	/* List for errors generated on VME */
-	struct list_head devices;	/* List of devices on this bridge */
+	/* List for registered errors handlers */
+	struct list_head vme_error_handlers;
+	/* List of devices on this bridge */
+	struct list_head devices;
 
 	/* Bridge Info - XXX Move to private structure? */
 	struct device *parent;	/* Parent device (eg. pdev->dev for PCI) */
@@ -168,13 +173,13 @@ struct vme_bridge {
 
 void vme_bus_error_handler(struct vme_bridge *bridge,
 			   unsigned long long address, int am);
-struct vme_bus_error *vme_find_error(struct vme_bridge *bridge, u32 aspace,
-				     unsigned long long address, size_t count);
-void vme_clear_errors(struct vme_bridge *bridge, u32 aspace,
-		      unsigned long long address, size_t count);
 void vme_irq_handler(struct vme_bridge *, int, int);
 
 int vme_register_bridge(struct vme_bridge *);
 void vme_unregister_bridge(struct vme_bridge *);
+struct vme_error_handler *vme_register_error_handler(
+	struct vme_bridge *bridge, u32 aspace,
+	unsigned long long address, size_t len);
+void vme_unregister_error_handler(struct vme_error_handler *handler);
 
 #endif /* _VME_BRIDGE_H_ */
-- 
1.8.3.1

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