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From:   Mihai Carabas <mihai.carabas@oracle.com>
To:     linux-kernel@vger.kernel.org
Cc:     gregkh@linuxfoundation.org, arnd@arndb.de, rdunlap@infradead.org,
        bobo.shaobowang@huawei.com,
        Mihai Carabas <mihai.carabas@oracle.com>
Subject: [PATCH v4 2/3] misc/pvpanic: probe multiple instances
Date:   Sat, 13 Feb 2021 21:44:06 +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 |  9 ++---
 drivers/misc/pvpanic/pvpanic.c      | 76 ++++++++++++++++++++++++++++++++-----
 drivers/misc/pvpanic/pvpanic.h      |  5 +--
 3 files changed, 73 insertions(+), 17 deletions(-)

diff --git a/drivers/misc/pvpanic/pvpanic-mmio.c b/drivers/misc/pvpanic/pvpanic-mmio.c
index 7454eeb..5425369 100644
--- a/drivers/misc/pvpanic/pvpanic-mmio.c
+++ b/drivers/misc/pvpanic/pvpanic-mmio.c
@@ -22,11 +22,12 @@
 MODULE_DESCRIPTION("pvpanic device driver");
 MODULE_LICENSE("GPL");
 
+static void __iomem *base;
+
 static int pvpanic_mmio_probe(struct platform_device *pdev)
 {
 	struct device *dev = &pdev->dev;
 	struct resource *res;
-	void __iomem *base;
 
 	res = platform_get_mem_or_io(pdev, 0);
 	if (!res)
@@ -47,15 +48,13 @@ static int pvpanic_mmio_probe(struct platform_device *pdev)
 		return -EINVAL;
 	}
 
-	pvpanic_probe(base);
-
-	return 0;
+	return pvpanic_probe(base);
 }
 
 static int pvpanic_mmio_remove(struct platform_device *pdev)
 {
 
-	pvpanic_remove();
+	pvpanic_remove(base);
 
 	return 0;
 }
diff --git a/drivers/misc/pvpanic/pvpanic.c b/drivers/misc/pvpanic/pvpanic.c
index 652ae01..43b65a3 100644
--- a/drivers/misc/pvpanic/pvpanic.c
+++ b/drivers/misc/pvpanic/pvpanic.c
@@ -14,15 +14,30 @@
 #include <linux/module.h>
 #include <linux/platform_device.h>
 #include <linux/types.h>
+#include <linux/cdev.h>
+#include <linux/list.h>
+#include <linux/slab.h>
 
 #include <uapi/misc/pvpanic.h>
 
-static void __iomem *base;
+struct pvpanic_instance {
+	void __iomem *base;
+	struct list_head list;
+};
+
+struct list_head pvpanic_list;
+spinlock_t pvpanic_lock;
 
 static void
 pvpanic_send_event(unsigned int event)
 {
-	iowrite8(event, base);
+	struct pvpanic_instance *pi_cur;
+
+	spin_lock(&pvpanic_lock);
+	list_for_each_entry(pi_cur, &pvpanic_list, list) {
+		iowrite8(event, pi_cur->base);
+	}
+	spin_unlock(&pvpanic_lock);
 }
 
 static int
@@ -44,19 +59,62 @@
 	.priority = 1, /* let this called before broken drm_fb_helper */
 };
 
-void pvpanic_probe(void __iomem *pbase)
+int pvpanic_probe(void __iomem *pbase)
 {
-	base = pbase;
-	atomic_notifier_chain_register(&panic_notifier_list,
-				       &pvpanic_panic_nb);
+	struct pvpanic_instance *pi;
+
+	if(!pbase)
+		return -EINVAL;
+
+	pi = kmalloc(sizeof(*pi), GFP_ATOMIC);
+	if (!pi)
+		return -ENOMEM;
+
+	pi->base = pbase;
+	spin_lock(&pvpanic_lock);
+	list_add(&pi->list, &pvpanic_list);
+	spin_unlock(&pvpanic_lock);
+
+	return 0;
 }
 EXPORT_SYMBOL_GPL(pvpanic_probe);
 
-void pvpanic_remove(void)
+void pvpanic_remove(void __iomem *pbase)
+{
+	struct pvpanic_instance *pi_cur, *pi_next;
+
+	if(!pbase)
+		return -EINVAL;
+
+	spin_lock(&pvpanic_lock);
+	list_for_each_entry_safe(pi_cur, pi_next, &pvpanic_list, list) {
+		if (pi_cur->base == pbase) {
+			list_del(&pi_cur->list);
+			kfree(pi_cur);
+			break;
+		}
+	}
+	spin_unlock(&pvpanic_lock);
+}
+EXPORT_SYMBOL_GPL(pvpanic_remove);
+
+static int pvpanic_init(void)
 {
+	INIT_LIST_HEAD(&pvpanic_list);
+	spin_lock_init(&pvpanic_lock);
+
+	atomic_notifier_chain_register(&panic_notifier_list,
+				       &pvpanic_panic_nb);
 
+	return 0;
+}
+
+static void pvpanic_exit(void)
+{
 	atomic_notifier_chain_unregister(&panic_notifier_list,
 					 &pvpanic_panic_nb);
-	base = NULL;
+
 }
-EXPORT_SYMBOL_GPL(pvpanic_remove);
+
+module_init(pvpanic_init);
+module_exit(pvpanic_exit);
diff --git a/drivers/misc/pvpanic/pvpanic.h b/drivers/misc/pvpanic/pvpanic.h
index 7e75dce..02023d7 100644
--- a/drivers/misc/pvpanic/pvpanic.h
+++ b/drivers/misc/pvpanic/pvpanic.h
@@ -8,10 +8,9 @@
 #ifndef PVPANIC_H_
 #define PVPANIC_H_
 
-
 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
 
-void pvpanic_probe(void __iomem *base);
-void pvpanic_remove(void);
+int pvpanic_probe(void __iomem *base);
+void pvpanic_remove(void __iomem *base);
 
 #endif /* PVPANIC_H_ */
-- 
1.8.3.1