media: Remove the legacy v4l2-clk API (85db876b) · Commits · EulixOS / Software / Kernel

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

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		.. 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

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		@@ -15,7 +15,6 @@ Video4Linux devices
		v4l2-controls
		v4l2-videobuf
		v4l2-videobuf2
		v4l2-clocks
		v4l2-dv-timings
		v4l2-flash-led-class
		v4l2-mc

drivers/media/v4l2-core/Makefile

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		@@ -6,7 +6,7 @@
		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

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		// SPDX-License-Identifier: GPL-2.0-only
		/*
		* V4L2 clock service
		*
		* Copyright (C) 2012-2013, Guennadi Liakhovetski <g.liakhovetski@gmx.de>
		*/

		#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

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		/* SPDX-License-Identifier: GPL-2.0-only */
		/*
		* V4L2 clock service
		*
		* Copyright (C) 2012-2013, Guennadi Liakhovetski <g.liakhovetski@gmx.de>
		*
		* 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