![Guennadi Liakhovetski](/assets/img/avatar_default.png)
Many bridges and video host controllers supply fixed rate always on clocks to their I2C devices. This patch adds two simple helpers to register and unregister such a clock. Signed-off-by: Guennadi Liakhovetski <g.liakhovetski@gmx.de> Signed-off-by: Mauro Carvalho Chehab <m.chehab@samsung.com>
282 lines
5.4 KiB
C
282 lines
5.4 KiB
C
/*
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* V4L2 clock service
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*
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* Copyright (C) 2012-2013, Guennadi Liakhovetski <g.liakhovetski@gmx.de>
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License version 2 as
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* published by the Free Software Foundation.
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*/
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#include <linux/atomic.h>
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#include <linux/device.h>
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#include <linux/errno.h>
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#include <linux/list.h>
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#include <linux/module.h>
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#include <linux/mutex.h>
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#include <linux/slab.h>
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#include <linux/string.h>
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#include <media/v4l2-clk.h>
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#include <media/v4l2-subdev.h>
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static DEFINE_MUTEX(clk_lock);
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static LIST_HEAD(clk_list);
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static struct v4l2_clk *v4l2_clk_find(const char *dev_id, const char *id)
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{
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struct v4l2_clk *clk;
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list_for_each_entry(clk, &clk_list, list) {
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if (strcmp(dev_id, clk->dev_id))
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continue;
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if (!id || !clk->id || !strcmp(clk->id, id))
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return clk;
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}
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return ERR_PTR(-ENODEV);
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}
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struct v4l2_clk *v4l2_clk_get(struct device *dev, const char *id)
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{
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struct v4l2_clk *clk;
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mutex_lock(&clk_lock);
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clk = v4l2_clk_find(dev_name(dev), id);
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if (!IS_ERR(clk))
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atomic_inc(&clk->use_count);
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mutex_unlock(&clk_lock);
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return clk;
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}
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EXPORT_SYMBOL(v4l2_clk_get);
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void v4l2_clk_put(struct v4l2_clk *clk)
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{
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struct v4l2_clk *tmp;
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if (IS_ERR(clk))
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return;
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mutex_lock(&clk_lock);
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list_for_each_entry(tmp, &clk_list, list)
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if (tmp == clk)
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atomic_dec(&clk->use_count);
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mutex_unlock(&clk_lock);
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}
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EXPORT_SYMBOL(v4l2_clk_put);
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static int v4l2_clk_lock_driver(struct v4l2_clk *clk)
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{
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struct v4l2_clk *tmp;
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int ret = -ENODEV;
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mutex_lock(&clk_lock);
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list_for_each_entry(tmp, &clk_list, list)
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if (tmp == clk) {
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ret = !try_module_get(clk->ops->owner);
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if (ret)
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ret = -EFAULT;
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break;
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}
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mutex_unlock(&clk_lock);
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return ret;
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}
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static void v4l2_clk_unlock_driver(struct v4l2_clk *clk)
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{
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module_put(clk->ops->owner);
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}
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int v4l2_clk_enable(struct v4l2_clk *clk)
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{
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int ret = v4l2_clk_lock_driver(clk);
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if (ret < 0)
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return ret;
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mutex_lock(&clk->lock);
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if (++clk->enable == 1 && clk->ops->enable) {
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ret = clk->ops->enable(clk);
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if (ret < 0)
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clk->enable--;
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}
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mutex_unlock(&clk->lock);
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return ret;
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}
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EXPORT_SYMBOL(v4l2_clk_enable);
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/*
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* You might Oops if you try to disabled a disabled clock, because then the
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* driver isn't locked and could have been unloaded by now, so, don't do that
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*/
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void v4l2_clk_disable(struct v4l2_clk *clk)
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{
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int enable;
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mutex_lock(&clk->lock);
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enable = --clk->enable;
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if (WARN(enable < 0, "Unbalanced %s() on %s:%s!\n", __func__,
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clk->dev_id, clk->id))
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clk->enable++;
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else if (!enable && clk->ops->disable)
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clk->ops->disable(clk);
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mutex_unlock(&clk->lock);
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v4l2_clk_unlock_driver(clk);
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}
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EXPORT_SYMBOL(v4l2_clk_disable);
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unsigned long v4l2_clk_get_rate(struct v4l2_clk *clk)
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{
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int ret = v4l2_clk_lock_driver(clk);
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if (ret < 0)
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return ret;
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mutex_lock(&clk->lock);
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if (!clk->ops->get_rate)
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ret = -ENOSYS;
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else
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ret = clk->ops->get_rate(clk);
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mutex_unlock(&clk->lock);
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v4l2_clk_unlock_driver(clk);
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return ret;
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}
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EXPORT_SYMBOL(v4l2_clk_get_rate);
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int v4l2_clk_set_rate(struct v4l2_clk *clk, unsigned long rate)
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{
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int ret = v4l2_clk_lock_driver(clk);
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if (ret < 0)
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return ret;
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mutex_lock(&clk->lock);
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if (!clk->ops->set_rate)
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ret = -ENOSYS;
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else
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ret = clk->ops->set_rate(clk, rate);
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mutex_unlock(&clk->lock);
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v4l2_clk_unlock_driver(clk);
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return ret;
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}
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EXPORT_SYMBOL(v4l2_clk_set_rate);
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struct v4l2_clk *v4l2_clk_register(const struct v4l2_clk_ops *ops,
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const char *dev_id,
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const char *id, void *priv)
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{
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struct v4l2_clk *clk;
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int ret;
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if (!ops || !dev_id)
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return ERR_PTR(-EINVAL);
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clk = kzalloc(sizeof(struct v4l2_clk), GFP_KERNEL);
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if (!clk)
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return ERR_PTR(-ENOMEM);
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clk->id = kstrdup(id, GFP_KERNEL);
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clk->dev_id = kstrdup(dev_id, GFP_KERNEL);
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if ((id && !clk->id) || !clk->dev_id) {
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ret = -ENOMEM;
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goto ealloc;
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}
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clk->ops = ops;
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clk->priv = priv;
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atomic_set(&clk->use_count, 0);
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mutex_init(&clk->lock);
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mutex_lock(&clk_lock);
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if (!IS_ERR(v4l2_clk_find(dev_id, id))) {
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mutex_unlock(&clk_lock);
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ret = -EEXIST;
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goto eexist;
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}
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list_add_tail(&clk->list, &clk_list);
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mutex_unlock(&clk_lock);
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return clk;
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eexist:
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ealloc:
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kfree(clk->id);
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kfree(clk->dev_id);
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kfree(clk);
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return ERR_PTR(ret);
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}
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EXPORT_SYMBOL(v4l2_clk_register);
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void v4l2_clk_unregister(struct v4l2_clk *clk)
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{
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if (WARN(atomic_read(&clk->use_count),
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"%s(): Refusing to unregister ref-counted %s:%s clock!\n",
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__func__, clk->dev_id, clk->id))
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return;
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mutex_lock(&clk_lock);
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list_del(&clk->list);
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mutex_unlock(&clk_lock);
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kfree(clk->id);
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kfree(clk->dev_id);
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kfree(clk);
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}
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EXPORT_SYMBOL(v4l2_clk_unregister);
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struct v4l2_clk_fixed {
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unsigned long rate;
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struct v4l2_clk_ops ops;
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};
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static unsigned long fixed_get_rate(struct v4l2_clk *clk)
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{
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struct v4l2_clk_fixed *priv = clk->priv;
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return priv->rate;
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}
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struct v4l2_clk *__v4l2_clk_register_fixed(const char *dev_id,
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const char *id, unsigned long rate, struct module *owner)
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{
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struct v4l2_clk *clk;
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struct v4l2_clk_fixed *priv = kzalloc(sizeof(*priv), GFP_KERNEL);
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if (!priv)
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return ERR_PTR(-ENOMEM);
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priv->rate = rate;
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priv->ops.get_rate = fixed_get_rate;
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priv->ops.owner = owner;
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clk = v4l2_clk_register(&priv->ops, dev_id, id, priv);
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if (IS_ERR(clk))
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kfree(priv);
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return clk;
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}
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EXPORT_SYMBOL(__v4l2_clk_register_fixed);
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void v4l2_clk_unregister_fixed(struct v4l2_clk *clk)
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{
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kfree(clk->priv);
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v4l2_clk_unregister(clk);
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}
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EXPORT_SYMBOL(v4l2_clk_unregister_fixed);
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