media: Remove the legacy v4l2-clk API

The V4L2 temporary clock helper API, was introduced
in late 2012 and, as mentioned in the documentation,
meant to be replaced by the generic clock API,
once the generic clock framework became available
on all relevant architectures.

The generic clock API is a well-established API (since a few
years now). The last few media capture drivers and sensors
using v4l2-clk have been converted to the generic clock framework.

We can now remove the v4l2-clk API.

Signed-off-by: Ezequiel Garcia <[e-mail]>
Acked-by: Petr Cvek <[e-mail]>
Signed-off-by: Sakari Ailus <[e-mail]>
Signed-off-by: Mauro Carvalho Chehab <[e-mail]>

Documentation/driver-api/media/v4l2-clocks.rst

···
-.. SPDX-License-Identifier: GPL-2.0
-
-V4L2 clocks
------------
-
-.. attention::
-
-	This is a temporary API and it shall be replaced by the generic
-	clock API, when the latter becomes widely available.
-
-Many subdevices, like camera sensors, TV decoders and encoders, need a clock
-signal to be supplied by the system. Often this clock is supplied by the
-respective bridge device. The Linux kernel provides a Common Clock Framework for
-this purpose. However, it is not (yet) available on all architectures. Besides,
-the nature of the multi-functional (clock, data + synchronisation, I2C control)
-connection of subdevices to the system might impose special requirements on the
-clock API usage. E.g. V4L2 has to support clock provider driver unregistration
-while a subdevice driver is holding a reference to the clock. For these reasons
-a V4L2 clock helper API has been developed and is provided to bridge and
-subdevice drivers.
-
-The API consists of two parts: two functions to register and unregister a V4L2
-clock source: v4l2_clk_register() and v4l2_clk_unregister() and calls to control
-a clock object, similar to the respective generic clock API calls:
-v4l2_clk_get(), v4l2_clk_put(), v4l2_clk_enable(), v4l2_clk_disable(),
-v4l2_clk_get_rate(), and v4l2_clk_set_rate(). Clock suppliers have to provide
-clock operations that will be called when clock users invoke respective API
-methods.
-
-It is expected that once the CCF becomes available on all relevant
-architectures this API will be removed.

Documentation/driver-api/media/v4l2-core.rst

···
     v4l2-controls
     v4l2-videobuf
     v4l2-videobuf2
-    v4l2-clocks
     v4l2-dv-timings
     v4l2-flash-led-class
     v4l2-mc

drivers/media/v4l2-core/Makefile

···
 tuner-objs	:=	tuner-core.o
 
 videodev-objs	:=	v4l2-dev.o v4l2-ioctl.o v4l2-device.o v4l2-fh.o \
-			v4l2-event.o v4l2-ctrls.o v4l2-subdev.o v4l2-clk.o \
+			v4l2-event.o v4l2-ctrls.o v4l2-subdev.o \
 			v4l2-async.o v4l2-common.o
 videodev-$(CONFIG_COMPAT) += v4l2-compat-ioctl32.o
 videodev-$(CONFIG_TRACEPOINTS) += v4l2-trace.o

drivers/media/v4l2-core/v4l2-clk.c

···
-// SPDX-License-Identifier: GPL-2.0-only
-/*
- * V4L2 clock service
- *
- * Copyright (C) 2012-2013, Guennadi Liakhovetski <[e-mail]>
- */
-
-#include <linux/atomic.h>
-#include <linux/clk.h>
-#include <linux/device.h>
-#include <linux/errno.h>
-#include <linux/list.h>
-#include <linux/module.h>
-#include <linux/mutex.h>
-#include <linux/of.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)
-{
-	struct v4l2_clk *clk;
-
-	list_for_each_entry(clk, &clk_list, list)
-		if (!strcmp(dev_id, clk->dev_id))
-			return clk;
-
-	return ERR_PTR(-ENODEV);
-}
-
-struct v4l2_clk *v4l2_clk_get(struct device *dev, const char *id)
-{
-	struct v4l2_clk *clk;
-	struct clk *ccf_clk = clk_get(dev, id);
-	char clk_name[V4L2_CLK_NAME_SIZE];
-
-	if (PTR_ERR(ccf_clk) == -EPROBE_DEFER)
-		return ERR_PTR(-EPROBE_DEFER);
-
-	if (!IS_ERR_OR_NULL(ccf_clk)) {
-		clk = kzalloc(sizeof(*clk), GFP_KERNEL);
-		if (!clk) {
-			clk_put(ccf_clk);
-			return ERR_PTR(-ENOMEM);
-		}
-		clk->clk = ccf_clk;
-
-		return clk;
-	}
-
-	mutex_lock(&clk_lock);
-	clk = v4l2_clk_find(dev_name(dev));
-
-	/* if dev_name is not found, try use the OF name to find again  */
-	if (PTR_ERR(clk) == -ENODEV && dev->of_node) {
-		v4l2_clk_name_of(clk_name, sizeof(clk_name), dev->of_node);
-		clk = v4l2_clk_find(clk_name);
-	}
-
-	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;
-
-	if (clk->clk) {
-		clk_put(clk->clk);
-		kfree(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;
-
-	if (clk->clk)
-		return clk_prepare_enable(clk->clk);
-
-	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;
-
-	if (clk->clk)
-		return clk_disable_unprepare(clk->clk);
-
-	mutex_lock(&clk->lock);
-
-	enable = --clk->enable;
-	if (WARN(enable < 0, "Unbalanced %s() on %s!\n", __func__,
-		 clk->dev_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;
-
-	if (clk->clk)
-		return clk_get_rate(clk->clk);
-
-	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;
-
-	if (clk->clk) {
-		long r = clk_round_rate(clk->clk, rate);
-		if (r < 0)
-			return r;
-		return clk_set_rate(clk->clk, r);
-	}
-
-	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,
-				   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->dev_id = kstrdup(dev_id, GFP_KERNEL);
-	if (!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))) {
-		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->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 clock!\n",
-		 __func__, clk->dev_id))
-		return;
-
-	mutex_lock(&clk_lock);
-	list_del(&clk->list);
-	mutex_unlock(&clk_lock);
-
-	kfree(clk->dev_id);
-	kfree(clk);
-}
-EXPORT_SYMBOL(v4l2_clk_unregister);
-
-struct v4l2_clk_fixed {
-	unsigned long rate;
-	struct v4l2_clk_ops ops;
-};
-
-static unsigned long fixed_get_rate(struct v4l2_clk *clk)
-{
-	struct v4l2_clk_fixed *priv = clk->priv;
-	return priv->rate;
-}
-
-struct v4l2_clk *__v4l2_clk_register_fixed(const char *dev_id,
-				unsigned long rate, struct module *owner)
-{
-	struct v4l2_clk *clk;
-	struct v4l2_clk_fixed *priv = kzalloc(sizeof(*priv), GFP_KERNEL);
-
-	if (!priv)
-		return ERR_PTR(-ENOMEM);
-
-	priv->rate = rate;
-	priv->ops.get_rate = fixed_get_rate;
-	priv->ops.owner = owner;
-
-	clk = v4l2_clk_register(&priv->ops, dev_id, priv);
-	if (IS_ERR(clk))
-		kfree(priv);
-
-	return clk;
-}
-EXPORT_SYMBOL(__v4l2_clk_register_fixed);
-
-void v4l2_clk_unregister_fixed(struct v4l2_clk *clk)
-{
-	kfree(clk->priv);
-	v4l2_clk_unregister(clk);
-}
-EXPORT_SYMBOL(v4l2_clk_unregister_fixed);

include/media/v4l2-clk.h

···
-/* SPDX-License-Identifier: GPL-2.0-only */
-/*
- * V4L2 clock service
- *
- * Copyright (C) 2012-2013, Guennadi Liakhovetski <[e-mail]>
- *
- * ATTENTION: This is a temporary API and it shall be replaced by the generic
- * clock API, when the latter becomes widely available.
- */
-
-#ifndef MEDIA_V4L2_CLK_H
-#define MEDIA_V4L2_CLK_H
-
-#include <linux/atomic.h>
-#include <linux/export.h>
-#include <linux/list.h>
-#include <linux/mutex.h>
-
-struct module;
-struct device;
-
-struct clk;
-struct v4l2_clk {
-	struct list_head list;
-	const struct v4l2_clk_ops *ops;
-	const char *dev_id;
-	int enable;
-	struct mutex lock; /* Protect the enable count */
-	atomic_t use_count;
-	struct clk *clk;
-	void *priv;
-};
-
-struct v4l2_clk_ops {
-	struct module	*owner;
-	int		(*enable)(struct v4l2_clk *clk);
-	void		(*disable)(struct v4l2_clk *clk);
-	unsigned long	(*get_rate)(struct v4l2_clk *clk);
-	int		(*set_rate)(struct v4l2_clk *clk, unsigned long);
-};
-
-struct v4l2_clk *v4l2_clk_register(const struct v4l2_clk_ops *ops,
-				   const char *dev_name,
-				   void *priv);
-void v4l2_clk_unregister(struct v4l2_clk *clk);
-struct v4l2_clk *v4l2_clk_get(struct device *dev, const char *id);
-void v4l2_clk_put(struct v4l2_clk *clk);
-int v4l2_clk_enable(struct v4l2_clk *clk);
-void v4l2_clk_disable(struct v4l2_clk *clk);
-unsigned long v4l2_clk_get_rate(struct v4l2_clk *clk);
-int v4l2_clk_set_rate(struct v4l2_clk *clk, unsigned long rate);
-
-struct module;
-
-struct v4l2_clk *__v4l2_clk_register_fixed(const char *dev_id,
-			unsigned long rate, struct module *owner);
-void v4l2_clk_unregister_fixed(struct v4l2_clk *clk);
-
-static inline struct v4l2_clk *v4l2_clk_register_fixed(const char *dev_id,
-							unsigned long rate)
-{
-	return __v4l2_clk_register_fixed(dev_id, rate, THIS_MODULE);
-}
-
-#define V4L2_CLK_NAME_SIZE 64
-
-#define v4l2_clk_name_i2c(name, size, adap, client) snprintf(name, size, \
-			  "%d-%04x", adap, client)
-
-#define v4l2_clk_name_of(name, size, node) snprintf(name, size, \
-			  "of-%pOF", node)
-
-#endif