[PATCH 23/27] powernv/opal: Notifier for OPAL events

[Gavin Shan]

The patch intends to implement the notifier for variable OPAL events.
It's notable that the notifier can be disabled dynamically. Also, the
notifier could be fired upon incoming OPAL interrupts, or enabling
the OPAL notifier.

Signed-off-by: Gavin Shan <shangw at linux.vnet.ibm.com>
---
 arch/powerpc/include/asm/opal.h       |    3 +
 arch/powerpc/platforms/powernv/opal.c |   79 ++++++++++++++++++++++++++++++++-
 2 files changed, 81 insertions(+), 1 deletions(-)

diff --git a/arch/powerpc/include/asm/opal.h b/arch/powerpc/include/asm/opal.h
index 2880797..64e7c84 100644
--- a/arch/powerpc/include/asm/opal.h
+++ b/arch/powerpc/include/asm/opal.h
@@ -644,6 +644,9 @@ extern void hvc_opal_init_early(void);
 extern int early_init_dt_scan_opal(unsigned long node, const char *uname,
 				   int depth, void *data);
 
+extern int opal_notifier_register(uint64_t mask, void (*cb)(uint64_t));
+extern void opal_notifier_enable(bool enable);
+
 extern int opal_get_chars(uint32_t vtermno, char *buf, int count);
 extern int opal_put_chars(uint32_t vtermno, const char *buf, int total_len);
 
diff --git a/arch/powerpc/platforms/powernv/opal.c b/arch/powerpc/platforms/powernv/opal.c
index 628c564..9bbbf93 100644
--- a/arch/powerpc/platforms/powernv/opal.c
+++ b/arch/powerpc/platforms/powernv/opal.c
@@ -26,11 +26,20 @@ struct opal {
 	u64 entry;
 } opal;
 
+struct opal_cb {
+	struct list_head list;
+	uint64_t mask;
+	void (*cb)(uint64_t);
+};
+
 static struct device_node *opal_node;
 static DEFINE_SPINLOCK(opal_write_lock);
 extern u64 opal_mc_secondary_handler[];
 static unsigned int *opal_irqs;
 static unsigned int opal_irq_count;
+static LIST_HEAD(opal_notifier);
+static DEFINE_SPINLOCK(opal_notifier_lock);
+static atomic_t opal_notifier_hold = ATOMIC_INIT(0);
 
 int __init early_init_dt_scan_opal(unsigned long node,
 				   const char *uname, int depth, void *data)
@@ -95,6 +104,74 @@ static int __init opal_register_exception_handlers(void)
 
 early_initcall(opal_register_exception_handlers);
 
+int opal_notifier_register(uint64_t mask, void (*cb)(uint64_t))
+{
+	unsigned long flags;
+	struct opal_cb *p, *tmp;
+
+	if (!mask || !cb) {
+		pr_warning("%s: Invalid argument (%llx, %p)!\n",
+			__func__, mask, cb);
+		return -EINVAL;
+	}
+
+	p = kzalloc(sizeof(*p), GFP_KERNEL);
+	if (!p) {
+		pr_warning("%s: Out of memory (%llx, %p)!\n",
+			__func__, mask, cb);
+		return -ENOMEM;
+	}
+	p->mask = mask;
+	p->cb   = cb;
+
+	spin_lock_irqsave(&opal_notifier_lock, flags);
+	list_for_each_entry(tmp, &opal_notifier, list) {
+		if (tmp->cb == cb || tmp->mask & mask) {
+			pr_warning("%s: Duplicate evnet handler (%llx, %p)\n",
+				__func__, tmp->mask, tmp->cb);
+			spin_unlock_irqrestore(&opal_notifier_lock, flags);
+			kfree(p);
+			return -EEXIST;
+		}
+	}
+
+	list_add_tail(&p->list, &opal_notifier);
+	spin_unlock_irqrestore(&opal_notifier_lock, flags);
+
+	return 0;
+}
+
+static void opal_do_notifier(uint64_t events)
+{
+	struct opal_cb *tmp;
+
+	if (atomic_read(&opal_notifier_hold))
+		return;
+	if (!events)
+		return;
+
+	list_for_each_entry(tmp, &opal_notifier, list) {
+		if (events & tmp->mask)
+			tmp->cb(events & tmp->mask);
+	}
+}
+
+void opal_notifier_enable(bool enable)
+{
+	int64_t rc;
+	uint64_t evt = 0;
+
+	if (enable) {
+		atomic_set(&opal_notifier_hold, 0);
+
+		/* Process pending events */
+		rc = opal_poll_events(&evt);
+		if (rc == OPAL_SUCCESS && evt)
+			opal_do_notifier(evt);
+	} else
+		atomic_set(&opal_notifier_hold, 1);
+}
+
 int opal_get_chars(uint32_t vtermno, char *buf, int count)
 {
 	s64 len, rc;
@@ -297,7 +374,7 @@ static irqreturn_t opal_interrupt(int irq, void *data)
 
 	opal_handle_interrupt(virq_to_hw(irq), &events);
 
-	/* XXX TODO: Do something with the events */
+	opal_do_notifier(events);
 
 	return IRQ_HANDLED;
 }
-- 
1.7.5.4