1 files changed, 242 insertions, 0 deletions
diff --git a/drivers/media/v4l2-core/v4l2-clk.c b/drivers/media/v4l2-core/v4l2-clk.c
new file mode 100644
index 00000000000..b67de8642b5
--- /dev/null
+++ b/drivers/media/v4l2-core/v4l2-clk.c
@@ -0,0 +1,242 @@
+/*
+ * V4L2 clock service
+ *
+ * Copyright (C) 2012-2013, Guennadi Liakhovetski <g.liakhovetski@gmx.de>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ */
+
+#include <linux/atomic.h>
+#include <linux/device.h>
+#include <linux/errno.h>
+#include <linux/list.h>
+#include <linux/module.h>
+#include <linux/mutex.h>
+#include <linux/slab.h>
+#include <linux/string.h>
+
+#include <media/v4l2-clk.h>
+#include <media/v4l2-subdev.h>
+
+static DEFINE_MUTEX(clk_lock);
+static LIST_HEAD(clk_list);
+
+static struct v4l2_clk *v4l2_clk_find(const char *dev_id, const char *id)
+{
+	struct v4l2_clk *clk;
+
+	list_for_each_entry(clk, &clk_list, list) {
+		if (strcmp(dev_id, clk->dev_id))
+			continue;
+
+		if (!id || !clk->id || !strcmp(clk->id, id))
+			return clk;
+	}
+
+	return ERR_PTR(-ENODEV);
+}
+
+struct v4l2_clk *v4l2_clk_get(struct device *dev, const char *id)
+{
+	struct v4l2_clk *clk;
+
+	mutex_lock(&clk_lock);
+	clk = v4l2_clk_find(dev_name(dev), id);
+
+	if (!IS_ERR(clk))
+		atomic_inc(&clk->use_count);
+	mutex_unlock(&clk_lock);
+
+	return clk;
+}
+EXPORT_SYMBOL(v4l2_clk_get);
+
+void v4l2_clk_put(struct v4l2_clk *clk)
+{
+	struct v4l2_clk *tmp;
+
+	if (IS_ERR(clk))
+		return;
+
+	mutex_lock(&clk_lock);
+
+	list_for_each_entry(tmp, &clk_list, list)
+		if (tmp == clk)
+			atomic_dec(&clk->use_count);
+
+	mutex_unlock(&clk_lock);
+}
+EXPORT_SYMBOL(v4l2_clk_put);
+
+static int v4l2_clk_lock_driver(struct v4l2_clk *clk)
+{
+	struct v4l2_clk *tmp;
+	int ret = -ENODEV;
+
+	mutex_lock(&clk_lock);
+
+	list_for_each_entry(tmp, &clk_list, list)
+		if (tmp == clk) {
+			ret = !try_module_get(clk->ops->owner);
+			if (ret)
+				ret = -EFAULT;
+			break;
+		}
+
+	mutex_unlock(&clk_lock);
+
+	return ret;
+}
+
+static void v4l2_clk_unlock_driver(struct v4l2_clk *clk)
+{
+	module_put(clk->ops->owner);
+}
+
+int v4l2_clk_enable(struct v4l2_clk *clk)
+{
+	int ret = v4l2_clk_lock_driver(clk);
+
+	if (ret < 0)
+		return ret;
+
+	mutex_lock(&clk->lock);
+
+	if (++clk->enable == 1 && clk->ops->enable) {
+		ret = clk->ops->enable(clk);
+		if (ret < 0)
+			clk->enable--;
+	}
+
+	mutex_unlock(&clk->lock);
+
+	return ret;
+}
+EXPORT_SYMBOL(v4l2_clk_enable);
+
+/*
+ * You might Oops if you try to disabled a disabled clock, because then the
+ * driver isn't locked and could have been unloaded by now, so, don't do that
+ */
+void v4l2_clk_disable(struct v4l2_clk *clk)
+{
+	int enable;
+
+	mutex_lock(&clk->lock);
+
+	enable = --clk->enable;
+	if (WARN(enable < 0, "Unbalanced %s() on %s:%s!\n", __func__,
+		 clk->dev_id, clk->id))
+		clk->enable++;
+	else if (!enable && clk->ops->disable)
+		clk->ops->disable(clk);
+
+	mutex_unlock(&clk->lock);
+
+	v4l2_clk_unlock_driver(clk);
+}
+EXPORT_SYMBOL(v4l2_clk_disable);
+
+unsigned long v4l2_clk_get_rate(struct v4l2_clk *clk)
+{
+	int ret = v4l2_clk_lock_driver(clk);
+
+	if (ret < 0)
+		return ret;
+
+	mutex_lock(&clk->lock);
+	if (!clk->ops->get_rate)
+		ret = -ENOSYS;
+	else
+		ret = clk->ops->get_rate(clk);
+	mutex_unlock(&clk->lock);
+
+	v4l2_clk_unlock_driver(clk);
+
+	return ret;
+}
+EXPORT_SYMBOL(v4l2_clk_get_rate);
+
+int v4l2_clk_set_rate(struct v4l2_clk *clk, unsigned long rate)
+{
+	int ret = v4l2_clk_lock_driver(clk);
+
+	if (ret < 0)
+		return ret;
+
+	mutex_lock(&clk->lock);
+	if (!clk->ops->set_rate)
+		ret = -ENOSYS;
+	else
+		ret = clk->ops->set_rate(clk, rate);
+	mutex_unlock(&clk->lock);
+
+	v4l2_clk_unlock_driver(clk);
+
+	return ret;
+}
+EXPORT_SYMBOL(v4l2_clk_set_rate);
+
+struct v4l2_clk *v4l2_clk_register(const struct v4l2_clk_ops *ops,
+				   const char *dev_id,
+				   const char *id, void *priv)
+{
+	struct v4l2_clk *clk;
+	int ret;
+
+	if (!ops || !dev_id)
+		return ERR_PTR(-EINVAL);
+
+	clk = kzalloc(sizeof(struct v4l2_clk), GFP_KERNEL);
+	if (!clk)
+		return ERR_PTR(-ENOMEM);
+
+	clk->id = kstrdup(id, GFP_KERNEL);
+	clk->dev_id = kstrdup(dev_id, GFP_KERNEL);
+	if ((id && !clk->id) || !clk->dev_id) {
+		ret = -ENOMEM;
+		goto ealloc;
+	}
+	clk->ops = ops;
+	clk->priv = priv;
+	atomic_set(&clk->use_count, 0);
+	mutex_init(&clk->lock);
+
+	mutex_lock(&clk_lock);
+	if (!IS_ERR(v4l2_clk_find(dev_id, id))) {
+		mutex_unlock(&clk_lock);
+		ret = -EEXIST;
+		goto eexist;
+	}
+	list_add_tail(&clk->list, &clk_list);
+	mutex_unlock(&clk_lock);
+
+	return clk;
+
+eexist:
+ealloc:
+	kfree(clk->id);
+	kfree(clk->dev_id);
+	kfree(clk);
+	return ERR_PTR(ret);
+}
+EXPORT_SYMBOL(v4l2_clk_register);
+
+void v4l2_clk_unregister(struct v4l2_clk *clk)
+{
+	if (WARN(atomic_read(&clk->use_count),
+		 "%s(): Refusing to unregister ref-counted %s:%s clock!\n",
+		 __func__, clk->dev_id, clk->id))
+		return;
+
+	mutex_lock(&clk_lock);
+	list_del(&clk->list);
+	mutex_unlock(&clk_lock);
+
+	kfree(clk->id);
+	kfree(clk->dev_id);
+	kfree(clk);
+}
+EXPORT_SYMBOL(v4l2_clk_unregister);