[PATCHv3 1/5] video: add hotplug detect notifier support
Hans Verkuil
hverkuil at xs4all.nl
Mon Jan 23 10:23:33 UTC 2017
From: Hans Verkuil <hans.verkuil at cisco.com>
Add support for video hotplug detect and EDID/ELD notifiers, which is used
to convey information from video drivers to their CEC and audio counterparts.
Based on an earlier version from Russell King:
https://patchwork.kernel.org/patch/9277043/
The hpd_notifier is a reference counted object containing the HPD/EDID/ELD state
of a video device.
When a new notifier is registered the current state will be reported to
that notifier at registration time.
Signed-off-by: Hans Verkuil <hans.verkuil at cisco.com>
Tested-by: Marek Szyprowski <m.szyprowski at samsung.com>
---
drivers/video/Kconfig | 3 +
drivers/video/Makefile | 1 +
drivers/video/hpd-notifier.c | 134 +++++++++++++++++++++++++++++++++++++++++++
include/linux/hpd-notifier.h | 109 +++++++++++++++++++++++++++++++++++
4 files changed, 247 insertions(+)
create mode 100644 drivers/video/hpd-notifier.c
create mode 100644 include/linux/hpd-notifier.h
diff --git a/drivers/video/Kconfig b/drivers/video/Kconfig
index 3c20af999893..a3a58d8481e9 100644
--- a/drivers/video/Kconfig
+++ b/drivers/video/Kconfig
@@ -36,6 +36,9 @@ config VIDEOMODE_HELPERS
config HDMI
bool
+config HPD_NOTIFIER
+ bool
+
if VT
source "drivers/video/console/Kconfig"
endif
diff --git a/drivers/video/Makefile b/drivers/video/Makefile
index 9ad3c17d6456..2697ae5c4166 100644
--- a/drivers/video/Makefile
+++ b/drivers/video/Makefile
@@ -1,5 +1,6 @@
obj-$(CONFIG_VGASTATE) += vgastate.o
obj-$(CONFIG_HDMI) += hdmi.o
+obj-$(CONFIG_HPD_NOTIFIER) += hpd-notifier.o
obj-$(CONFIG_VT) += console/
obj-$(CONFIG_LOGO) += logo/
diff --git a/drivers/video/hpd-notifier.c b/drivers/video/hpd-notifier.c
new file mode 100644
index 000000000000..971e823ead00
--- /dev/null
+++ b/drivers/video/hpd-notifier.c
@@ -0,0 +1,134 @@
+#include <linux/export.h>
+#include <linux/hpd-notifier.h>
+#include <linux/string.h>
+#include <linux/slab.h>
+#include <linux/list.h>
+
+static LIST_HEAD(hpd_notifiers);
+static DEFINE_MUTEX(hpd_notifiers_lock);
+
+struct hpd_notifier *hpd_notifier_get(struct device *dev)
+{
+ struct hpd_notifier *n;
+
+ mutex_lock(&hpd_notifiers_lock);
+ list_for_each_entry(n, &hpd_notifiers, head) {
+ if (n->dev == dev) {
+ mutex_unlock(&hpd_notifiers_lock);
+ kref_get(&n->kref);
+ return n;
+ }
+ }
+ n = kzalloc(sizeof(*n), GFP_KERNEL);
+ if (!n)
+ goto unlock;
+ n->dev = dev;
+ mutex_init(&n->lock);
+ BLOCKING_INIT_NOTIFIER_HEAD(&n->notifiers);
+ kref_init(&n->kref);
+ list_add_tail(&n->head, &hpd_notifiers);
+unlock:
+ mutex_unlock(&hpd_notifiers_lock);
+ return n;
+}
+EXPORT_SYMBOL_GPL(hpd_notifier_get);
+
+static void hpd_notifier_release(struct kref *kref)
+{
+ struct hpd_notifier *n =
+ container_of(kref, struct hpd_notifier, kref);
+
+ list_del(&n->head);
+ kfree(n->edid);
+ kfree(n);
+}
+
+void hpd_notifier_put(struct hpd_notifier *n)
+{
+ mutex_lock(&hpd_notifiers_lock);
+ kref_put(&n->kref, hpd_notifier_release);
+ mutex_unlock(&hpd_notifiers_lock);
+}
+EXPORT_SYMBOL_GPL(hpd_notifier_put);
+
+int hpd_notifier_register(struct hpd_notifier *n, struct notifier_block *nb)
+{
+ int ret = blocking_notifier_chain_register(&n->notifiers, nb);
+
+ if (ret)
+ return ret;
+ kref_get(&n->kref);
+ mutex_lock(&n->lock);
+ if (n->connected) {
+ blocking_notifier_call_chain(&n->notifiers, HPD_CONNECTED, n);
+ if (n->edid_size)
+ blocking_notifier_call_chain(&n->notifiers, HPD_NEW_EDID, n);
+ if (n->has_eld)
+ blocking_notifier_call_chain(&n->notifiers, HPD_NEW_ELD, n);
+ }
+ mutex_unlock(&n->lock);
+ return 0;
+}
+EXPORT_SYMBOL_GPL(hpd_notifier_register);
+
+int hpd_notifier_unregister(struct hpd_notifier *n, struct notifier_block *nb)
+{
+ int ret = blocking_notifier_chain_unregister(&n->notifiers, nb);
+
+ if (ret == 0)
+ hpd_notifier_put(n);
+ return ret;
+}
+EXPORT_SYMBOL_GPL(hpd_notifier_unregister);
+
+void hpd_event_connect(struct hpd_notifier *n)
+{
+ mutex_lock(&n->lock);
+ n->connected = true;
+ blocking_notifier_call_chain(&n->notifiers, HPD_CONNECTED, n);
+ mutex_unlock(&n->lock);
+}
+EXPORT_SYMBOL_GPL(hpd_event_connect);
+
+void hpd_event_disconnect(struct hpd_notifier *n)
+{
+ mutex_lock(&n->lock);
+ n->connected = false;
+ n->has_eld = false;
+ n->edid_size = 0;
+ blocking_notifier_call_chain(&n->notifiers, HPD_DISCONNECTED, n);
+ mutex_unlock(&n->lock);
+}
+EXPORT_SYMBOL_GPL(hpd_event_disconnect);
+
+int hpd_event_new_edid(struct hpd_notifier *n, const void *edid, size_t size)
+{
+ mutex_lock(&n->lock);
+ if (n->edid_allocated_size < size) {
+ void *p = kmalloc(size, GFP_KERNEL);
+
+ if (p == NULL) {
+ mutex_unlock(&n->lock);
+ return -ENOMEM;
+ }
+ kfree(n->edid);
+ n->edid = p;
+ n->edid_allocated_size = size;
+ }
+ memcpy(n->edid, edid, size);
+ n->edid_size = size;
+ blocking_notifier_call_chain(&n->notifiers, HPD_NEW_EDID, n);
+ mutex_unlock(&n->lock);
+ return 0;
+}
+EXPORT_SYMBOL_GPL(hpd_event_new_edid);
+
+void hpd_event_new_eld(struct hpd_notifier *n, const u8 eld[128])
+{
+ mutex_lock(&n->lock);
+ memcpy(n->eld, eld, sizeof(n->eld));
+ n->has_eld = true;
+ blocking_notifier_call_chain(&n->notifiers, HPD_NEW_ELD, n);
+ mutex_unlock(&n->lock);
+}
+EXPORT_SYMBOL_GPL(hpd_event_new_eld);
diff --git a/include/linux/hpd-notifier.h b/include/linux/hpd-notifier.h
new file mode 100644
index 000000000000..4dcb4515d2b2
--- /dev/null
+++ b/include/linux/hpd-notifier.h
@@ -0,0 +1,109 @@
+/*
+ * hpd-notifier.h - notify interested parties of (dis)connect and EDID
+ * events
+ *
+ * Copyright 2016 Russell King <rmk+kernel at arm.linux.org.uk>
+ * Copyright 2016 Cisco Systems, Inc. and/or its affiliates. All rights reserved.
+ */
+
+#ifndef LINUX_HPD_NOTIFIER_H
+#define LINUX_HPD_NOTIFIER_H
+
+#include <linux/types.h>
+#include <linux/notifier.h>
+#include <linux/kref.h>
+
+enum {
+ HPD_CONNECTED,
+ HPD_DISCONNECTED,
+ HPD_NEW_EDID,
+ HPD_NEW_ELD,
+};
+
+struct device;
+
+struct hpd_notifier {
+ struct mutex lock;
+ struct list_head head;
+ struct kref kref;
+ struct blocking_notifier_head notifiers;
+ struct device *dev;
+
+ /* Current state */
+ bool connected;
+ bool has_eld;
+ unsigned char eld[128];
+ void *edid;
+ size_t edid_size;
+ size_t edid_allocated_size;
+};
+
+/**
+ * hpd_notifier_get - find or create a new hpd_notifier for the given device.
+ * @dev: device that sends the events.
+ *
+ * If a notifier for device @dev already exists, then increase the refcount
+ * and return that notifier.
+ *
+ * If it doesn't exist, then allocate a new notifier struct and return a
+ * pointer to that new struct.
+ *
+ * Return NULL if the memory could not be allocated.
+ */
+struct hpd_notifier *hpd_notifier_get(struct device *dev);
+
+/**
+ * hpd_notifier_put - decrease refcount and delete when the refcount reaches 0.
+ * @n: notifier
+ */
+void hpd_notifier_put(struct hpd_notifier *n);
+
+/**
+ * hpd_notifier_register - register the notifier with the notifier_block.
+ * @n: the HPD notifier
+ * @nb: the notifier_block
+ */
+int hpd_notifier_register(struct hpd_notifier *n, struct notifier_block *nb);
+
+/**
+ * hpd_notifier_unregister - unregister the notifier with the notifier_block.
+ * @n: the HPD notifier
+ * @nb: the notifier_block
+ */
+int hpd_notifier_unregister(struct hpd_notifier *n, struct notifier_block *nb);
+
+/**
+ * hpd_event_connect - send a connect event.
+ * @n: the HPD notifier
+ *
+ * Send an HPD_CONNECTED event to any registered parties.
+ */
+void hpd_event_connect(struct hpd_notifier *n);
+
+/**
+ * hpd_event_disconnect - send a disconnect event.
+ * @n: the HPD notifier
+ *
+ * Send an HPD_DISCONNECTED event to any registered parties.
+ */
+void hpd_event_disconnect(struct hpd_notifier *n);
+
+/**
+ * hpd_event_new_edid - send a new EDID event.
+ * @n: the HPD notifier
+ *
+ * Send an HPD_NEW_EDID event to any registered parties.
+ * This function will make a copy the EDID so it can return -ENOMEM if
+ * no memory could be allocated.
+ */
+int hpd_event_new_edid(struct hpd_notifier *n, const void *edid, size_t size);
+
+/**
+ * hpd_event_new_eld - send a new ELD event.
+ * @n: the HPD notifier
+ *
+ * Send an HPD_NEW_ELD event to any registered parties.
+ */
+void hpd_event_new_eld(struct hpd_notifier *n, const u8 eld[128]);
+
+#endif
--
2.11.0
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