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From:   Mihai Carabas <mihai.carabas@oracle.com>
To:     linux-kernel@vger.kernel.org
Cc:     gregkh@linuxfoundation.org, arnd@arndb.de,
        bobo.shaobowang@huawei.com, rdunlap@infradead.org,
        Mihai Carabas <mihai.carabas@oracle.com>
Subject: [PATCH v6 2/3] misc/pvpanic: probe multiple instances
Date:   Mon, 22 Mar 2021 18:44:26 +0200
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Create the mecahism that allows multiple pvpanic instances to call
pvpanic_probe and receive panic events. A global list will retain all the
mapped addresses where to write panic events.

Signed-off-by: Mihai Carabas <mihai.carabas@oracle.com>
---
 drivers/misc/pvpanic/pvpanic-mmio.c | 41 ++++++++++++---------
 drivers/misc/pvpanic/pvpanic.c      | 72 ++++++++++++++++++++++++++-----------
 drivers/misc/pvpanic/pvpanic.h      | 12 +++++--
 3 files changed, 86 insertions(+), 39 deletions(-)

diff --git a/drivers/misc/pvpanic/pvpanic-mmio.c b/drivers/misc/pvpanic/pvpanic-mmio.c
index 801d892..0dd0e35 100644
--- a/drivers/misc/pvpanic/pvpanic-mmio.c
+++ b/drivers/misc/pvpanic/pvpanic-mmio.c
@@ -14,6 +14,7 @@
 #include <linux/module.h>
 #include <linux/platform_device.h>
 #include <linux/types.h>
+#include <linux/slab.h>
 
 #include <uapi/misc/pvpanic.h>
 
@@ -23,25 +24,26 @@
 MODULE_DESCRIPTION("pvpanic device driver");
 MODULE_LICENSE("GPL");
 
-static void __iomem *base;
-static unsigned int capability = PVPANIC_PANICKED | PVPANIC_CRASH_LOADED;
-static unsigned int events;
-
 static ssize_t capability_show(struct device *dev,
 			       struct device_attribute *attr, char *buf)
 {
-	return sysfs_emit(buf, "%x\n", capability);
+	struct pvpanic_instance *pi = dev_get_drvdata(dev);
+
+	return sysfs_emit(buf, "%x\n", pi->capability);
 }
 static DEVICE_ATTR_RO(capability);
 
 static ssize_t events_show(struct device *dev,  struct device_attribute *attr, char *buf)
 {
-	return sysfs_emit(buf, "%x\n", events);
+	struct pvpanic_instance *pi = dev_get_drvdata(dev);
+
+	return sysfs_emit(buf, "%x\n", pi->events);
 }
 
 static ssize_t events_store(struct device *dev,  struct device_attribute *attr,
 			    const char *buf, size_t count)
 {
+	struct pvpanic_instance *pi = dev_get_drvdata(dev);
 	unsigned int tmp;
 	int err;
 
@@ -49,15 +51,12 @@ static ssize_t events_store(struct device *dev,  struct device_attribute *attr,
 	if (err)
 		return err;
 
-	if ((tmp & capability) != tmp)
+	if ((tmp & pi->capability) != tmp)
 		return -EINVAL;
 
-	events = tmp;
-
-	pvpanic_set_events(events);
+	pi->events = tmp;
 
 	return count;
-
 }
 static DEVICE_ATTR_RW(events);
 
@@ -71,6 +70,7 @@ static ssize_t events_store(struct device *dev,  struct device_attribute *attr,
 static int pvpanic_mmio_probe(struct platform_device *pdev)
 {
 	struct device *dev = &pdev->dev;
+	struct pvpanic_instance *pi;
 	struct resource *res;
 	void __iomem *base;
 
@@ -93,19 +93,28 @@ static int pvpanic_mmio_probe(struct platform_device *pdev)
 		return -EINVAL;
 	}
 
+	pi = kmalloc(sizeof(*pi), GFP_ATOMIC);
+	if (!pi)
+		return -ENOMEM;
+
+	pi->base = base;
+	pi->capability = PVPANIC_PANICKED | PVPANIC_CRASH_LOADED;
+
 	/* initlize capability by RDPT */
-	capability &= ioread8(base);
-	events = capability;
+	pi->capability &= ioread8(base);
+	pi->events = pi->capability;
 
-	pvpanic_probe(base, capability);
+	dev_set_drvdata(dev, pi);
 
-	return 0;
+	return pvpanic_probe(pi);
 }
 
 static int pvpanic_mmio_remove(struct platform_device *pdev)
 {
+	struct pvpanic_instance *pi = dev_get_drvdata(&pdev->dev);
 
-	pvpanic_remove();
+	pvpanic_remove(pi);
+	kfree(pi);
 
 	return 0;
 }
diff --git a/drivers/misc/pvpanic/pvpanic.c b/drivers/misc/pvpanic/pvpanic.c
index 11d029c..ac41edb 100644
--- a/drivers/misc/pvpanic/pvpanic.c
+++ b/drivers/misc/pvpanic/pvpanic.c
@@ -14,20 +14,27 @@
 #include <linux/module.h>
 #include <linux/platform_device.h>
 #include <linux/types.h>
+#include <linux/cdev.h>
+#include <linux/list.h>
 
 #include <uapi/misc/pvpanic.h>
 
 #include "pvpanic.h"
 
-static void __iomem *base;
-static unsigned int capability;
-static unsigned int events;
+struct list_head pvpanic_list;
+spinlock_t pvpanic_lock;
 
 static void
 pvpanic_send_event(unsigned int event)
 {
-	if (event & capability & events)
-		iowrite8(event, base);
+	struct pvpanic_instance *pi_cur;
+
+	spin_lock(&pvpanic_lock);
+	list_for_each_entry(pi_cur, &pvpanic_list, list) {
+		if (event & pi_cur->capability & pi_cur->events)
+			iowrite8(event, pi_cur->base);
+	}
+	spin_unlock(&pvpanic_lock);
 }
 
 static int
@@ -49,29 +56,54 @@
 	.priority = 1, /* let this called before broken drm_fb_helper */
 };
 
-void pvpanic_probe(void __iomem *pbase, unsigned int dev_cap)
+int pvpanic_probe(struct pvpanic_instance *pi)
 {
-	base = pbase;
-	capability = dev_cap;
-	events = capability;
+	if (!pi || !pi->base)
+		return -EINVAL;
+
+	spin_lock(&pvpanic_lock);
+	list_add(&pi->list, &pvpanic_list);
+	spin_unlock(&pvpanic_lock);
 
-	if (capability)
-		atomic_notifier_chain_register(&panic_notifier_list,
-					       &pvpanic_panic_nb);
+	return 0;
 }
 EXPORT_SYMBOL_GPL(pvpanic_probe);
 
-void pvpanic_remove(void)
+void pvpanic_remove(struct pvpanic_instance *pi)
 {
-	if (capability)
-		atomic_notifier_chain_unregister(&panic_notifier_list,
-						 &pvpanic_panic_nb);
-	base = NULL;
+	struct pvpanic_instance *pi_cur, *pi_next;
+
+	if (!pi)
+		return;
+
+	spin_lock(&pvpanic_lock);
+	list_for_each_entry_safe(pi_cur, pi_next, &pvpanic_list, list) {
+		if (pi_cur == pi) {
+			list_del(&pi_cur->list);
+			break;
+		}
+	}
+	spin_unlock(&pvpanic_lock);
 }
 EXPORT_SYMBOL_GPL(pvpanic_remove);
 
-void pvpanic_set_events(unsigned int dev_events)
+static int pvpanic_init(void)
 {
-	events = dev_events;
+	INIT_LIST_HEAD(&pvpanic_list);
+	spin_lock_init(&pvpanic_lock);
+
+	atomic_notifier_chain_register(&panic_notifier_list,
+				       &pvpanic_panic_nb);
+
+	return 0;
 }
-EXPORT_SYMBOL_GPL(pvpanic_set_events);
+
+static void pvpanic_exit(void)
+{
+	atomic_notifier_chain_unregister(&panic_notifier_list,
+					 &pvpanic_panic_nb);
+
+}
+
+module_init(pvpanic_init);
+module_exit(pvpanic_exit);
diff --git a/drivers/misc/pvpanic/pvpanic.h b/drivers/misc/pvpanic/pvpanic.h
index 3abe15f..1afccc2 100644
--- a/drivers/misc/pvpanic/pvpanic.h
+++ b/drivers/misc/pvpanic/pvpanic.h
@@ -8,8 +8,14 @@
 #ifndef PVPANIC_H_
 #define PVPANIC_H_
 
-void pvpanic_probe(void __iomem *base, unsigned int dev_cap);
-void pvpanic_remove(void);
-void pvpanic_set_events(unsigned int dev_events);
+struct pvpanic_instance {
+	void __iomem *base;
+	unsigned int capability;
+	unsigned int events;
+	struct list_head list;
+};
+
+int pvpanic_probe(struct pvpanic_instance *pi);
+void pvpanic_remove(struct pvpanic_instance *pi);
 
 #endif /* PVPANIC_H_ */
-- 
1.8.3.1