// SPDX-License-Identifier: MIT
/*
* Copyright (C) 2020 - 2021 Red Hat, Inc.
*
* Authors:
* Hans de Goede <[email protected]>
*/
#include <linux/device.h>
#include <linux/kernel.h>
#include <linux/list.h>
#include <linux/module.h>
#include <linux/mutex.h>
#include <linux/slab.h>
#include <drm/drm_privacy_screen_machine.h>
#include <drm/drm_privacy_screen_consumer.h>
#include <drm/drm_privacy_screen_driver.h>
#include "drm_internal.h"
/**
* DOC: overview
*
* This class allows non KMS drivers, from e.g. drivers/platform/x86 to
* register a privacy-screen device, which the KMS drivers can then use
* to implement the standard privacy-screen properties, see
* :ref:`Standard Connector Properties<standard_connector_properties>`.
*
* KMS drivers using a privacy-screen class device are advised to use the
* drm_connector_attach_privacy_screen_provider() and
* drm_connector_update_privacy_screen() helpers for dealing with this.
*/
#define to_drm_privacy_screen(dev) \
container_of(dev, struct drm_privacy_screen, dev)
static DEFINE_MUTEX(drm_privacy_screen_lookup_lock);
static LIST_HEAD(drm_privacy_screen_lookup_list);
static DEFINE_MUTEX(drm_privacy_screen_devs_lock);
static LIST_HEAD(drm_privacy_screen_devs);
/*** drm_privacy_screen_machine.h functions ***/
/**
* drm_privacy_screen_lookup_add - add an entry to the static privacy-screen
* lookup list
* @lookup: lookup list entry to add
*
* Add an entry to the static privacy-screen lookup list. Note the
* &struct list_head which is part of the &struct drm_privacy_screen_lookup
* gets added to a list owned by the privacy-screen core. So the passed in
* &struct drm_privacy_screen_lookup must not be free-ed until it is removed
* from the lookup list by calling drm_privacy_screen_lookup_remove().
*/
void drm_privacy_screen_lookup_add(struct drm_privacy_screen_lookup *lookup)
{
mutex_lock(&drm_privacy_screen_lookup_lock);
list_add(&lookup->list, &drm_privacy_screen_lookup_list);
mutex_unlock(&drm_privacy_screen_lookup_lock);
}
EXPORT_SYMBOL(drm_privacy_screen_lookup_add);
/**
* drm_privacy_screen_lookup_remove - remove an entry to the static
* privacy-screen lookup list
* @lookup: lookup list entry to remove
*
* Remove an entry previously added with drm_privacy_screen_lookup_add()
* from the static privacy-screen lookup list.
*/
void drm_privacy_screen_lookup_remove(struct drm_privacy_screen_lookup *lookup)
{
mutex_lock(&drm_privacy_screen_lookup_lock);
list_del(&lookup->list);
mutex_unlock(&drm_privacy_screen_lookup_lock);
}
EXPORT_SYMBOL(drm_privacy_screen_lookup_remove);
/*** drm_privacy_screen_consumer.h functions ***/
static struct drm_privacy_screen *drm_privacy_screen_get_by_name(
const char *name)
{
struct drm_privacy_screen *priv;
struct device *dev = NULL;
mutex_lock(&drm_privacy_screen_devs_lock);
list_for_each_entry(priv, &drm_privacy_screen_devs, list) {
if (strcmp(dev_name(&priv->dev), name) == 0) {
dev = get_device(&priv->dev);
break;
}
}
mutex_unlock(&drm_privacy_screen_devs_lock);
return dev ? to_drm_privacy_screen(dev) : NULL;
}
/**
* drm_privacy_screen_get - get a privacy-screen provider
* @dev: consumer-device for which to get a privacy-screen provider
* @con_id: (video)connector name for which to get a privacy-screen provider
*
* Get a privacy-screen provider for a privacy-screen attached to the
* display described by the @dev and @con_id parameters.
*
* Return:
* * A pointer to a &struct drm_privacy_screen on success.
* * ERR_PTR(-ENODEV) if no matching privacy-screen is found
* * ERR_PTR(-EPROBE_DEFER) if there is a matching privacy-screen,
* but it has not been registered yet.
*/
struct drm_privacy_screen *drm_privacy_screen_get(struct device *dev,
const char *con_id)
{
const char *dev_id = dev ? dev_name(dev) : NULL;
struct drm_privacy_screen_lookup *l;
struct drm_privacy_screen *priv;
const char *provider = NULL;
int match, best = -1;
/*
* For now we only support using a static lookup table, which is
* populated by the drm_privacy_screen_arch_init() call. This should
* be extended with device-tree / fw_node lookup when support is added
* for device-tree using hardware with a privacy-screen.
*
* The lookup algorithm was shamelessly taken from the clock
* framework:
*
* We do slightly fuzzy matching here:
* An entry with a NULL ID is assumed to be a wildcard.
* If an entry has a device ID, it must match
* If an entry has a connection ID, it must match
* Then we take the most specific entry - with the following order
* of precedence: dev+con > dev only > con only.
*/
mutex_lock(&drm_privacy_screen_lookup_lock);
list_for_each_entry(l, &drm_privacy_screen_lookup_list, list) {
match = 0;
if (l->dev_id) {
if (!dev_id || strcmp(l->dev_id, dev_id))
continue;
match += 2;
}
if (l->con_id) {
if (!con_id || strcmp(l->con_id, con_id))
continue;
match += 1;
}
if (match > best) {
provider = l->provider;
best = match;
}
}
mutex_unlock(&drm_privacy_screen_lookup_lock);
if (!provider)
return ERR_PTR(-ENODEV);
priv = drm_privacy_screen_get_by_name(provider);
if (!priv)
return ERR_PTR(-EPROBE_DEFER);
return priv;
}
EXPORT_SYMBOL(drm_privacy_screen_get);
/**
* drm_privacy_screen_put - release a privacy-screen reference
* @priv: privacy screen reference to release
*
* Release a privacy-screen provider reference gotten through
* drm_privacy_screen_get(). May be called with a NULL or ERR_PTR,
* in which case it is a no-op.
*/
void drm_privacy_screen_put(struct drm_privacy_screen *priv)
{
if (IS_ERR_OR_NULL(priv))
return;
put_device(&priv->dev);
}
EXPORT_SYMBOL(drm_privacy_screen_put);
/**
* drm_privacy_screen_set_sw_state - set a privacy-screen's sw-state
* @priv: privacy screen to set the sw-state for
* @sw_state: new sw-state value to set
*
* Set the sw-state of a privacy screen. If the privacy-screen is not
* in a locked hw-state, then the actual and hw-state of the privacy-screen
* will be immediately updated to the new value. If the privacy-screen is
* in a locked hw-state, then the new sw-state will be remembered as the
* requested state to put the privacy-screen in when it becomes unlocked.
*
* Return: 0 on success, negative error code on failure.
*/
int drm_privacy_screen_set_sw_state(struct drm_privacy_screen *priv,
enum drm_privacy_screen_status sw_state)
{
int ret = 0;
mutex_lock(&priv->lock);
if (!priv->ops) {
ret = -ENODEV;
goto out;
}
/*
* As per the DRM connector properties documentation, setting the
* sw_state while the hw_state is locked is allowed. In this case
* it is a no-op other then storing the new sw_state so that it
* can be honored when the state gets unlocked.
* Also skip the set if the hw already is in the desired state.
*/
if (priv->hw_state >= PRIVACY_SCREEN_DISABLED_LOCKED ||
priv->hw_state == sw_state) {
priv->sw_state = sw_state;
goto out;
}
ret = priv->ops->set_sw_state(priv, sw_state);
out:
mutex_unlock(&priv->lock);
return ret;
}
EXPORT_SYMBOL(drm_privacy_screen_set_sw_state);
/**
* drm_privacy_screen_get_state - get privacy-screen's current state
* @priv: privacy screen to get the state for
* @sw_state_ret: address where to store the privacy-screens current sw-state
* @hw_state_ret: address where to store the privacy-screens current hw-state
*
* Get the current state of a privacy-screen, both the sw-state and the
* hw-state.
*/
void drm_privacy_screen_get_state(struct drm_privacy_screen *priv,
enum drm_privacy_screen_status *sw_state_ret,
enum drm_privacy_screen_status *hw_state_ret)
{
mutex_lock(&priv->lock);
*sw_state_ret = priv->sw_state;
*hw_state_ret = priv->hw_state;
mutex_unlock(&priv->lock);
}
EXPORT_SYMBOL(drm_privacy_screen_get_state);
/**
* drm_privacy_screen_register_notifier - register a notifier
* @priv: Privacy screen to register the notifier with
* @nb: Notifier-block for the notifier to register
*
* Register a notifier with the privacy-screen to be notified of changes made
* to the privacy-screen state from outside of the privacy-screen class.
* E.g. the state may be changed by the hardware itself in response to a
* hotkey press.
*
* The notifier is called with no locks held. The new hw_state and sw_state
* can be retrieved using the drm_privacy_screen_get_state() function.
* A pointer to the drm_privacy_screen's struct is passed as the ``void *data``
* argument of the notifier_block's notifier_call.
*
* The notifier will NOT be called when changes are made through
* drm_privacy_screen_set_sw_state(). It is only called for external changes.
*
* Return: 0 on success, negative error code on failure.
*/
int drm_privacy_screen_register_notifier(struct drm_privacy_screen *priv,
struct notifier_block *nb)
{
return blocking_notifier_chain_register(&priv->notifier_head, nb);
}
EXPORT_SYMBOL(drm_privacy_screen_register_notifier);
/**
* drm_privacy_screen_unregister_notifier - unregister a notifier
* @priv: Privacy screen to register the notifier with
* @nb: Notifier-block for the notifier to register
*
* Unregister a notifier registered with drm_privacy_screen_register_notifier().
*
* Return: 0 on success, negative error code on failure.
*/
int drm_privacy_screen_unregister_notifier(struct drm_privacy_screen *priv,
struct notifier_block *nb)
{
return blocking_notifier_chain_unregister(&priv->notifier_head, nb);
}
EXPORT_SYMBOL(drm_privacy_screen_unregister_notifier);
/*** drm_privacy_screen_driver.h functions ***/
static ssize_t sw_state_show(struct device *dev,
struct device_attribute *attr, char *buf)
{
struct drm_privacy_screen *priv = to_drm_privacy_screen(dev);
const char * const sw_state_names[] = {
"Disabled",
"Enabled",
};
ssize_t ret;
mutex_lock(&priv->lock);
if (!priv->ops)
ret = -ENODEV;
else if (WARN_ON(priv->sw_state >= ARRAY_SIZE(sw_state_names)))
ret = -ENXIO;
else
ret = sprintf(buf, "%s\n", sw_state_names[priv->sw_state]);
mutex_unlock(&priv->lock);
return ret;
}
/*
* RO: Do not allow setting the sw_state through sysfs, this MUST be done
* through the drm_properties on the drm_connector.
*/
static DEVICE_ATTR_RO(sw_state);
static ssize_t hw_state_show(struct device *dev,
struct device_attribute *attr, char *buf)
{
struct drm_privacy_screen *priv = to_drm_privacy_screen(dev);
const char * const hw_state_names[] = {
"Disabled",
"Enabled",
"Disabled, locked",
"Enabled, locked",
};
ssize_t ret;
mutex_lock(&priv->lock);
if (!priv->ops)
ret = -ENODEV;
else if (WARN_ON(priv->hw_state >= ARRAY_SIZE(hw_state_names)))
ret = -ENXIO;
else
ret = sprintf(buf, "%s\n", hw_state_names[priv->hw_state]);
mutex_unlock(&priv->lock);
return ret;
}
static DEVICE_ATTR_RO(hw_state);
static struct attribute *drm_privacy_screen_attrs[] = {
&dev_attr_sw_state.attr,
&dev_attr_hw_state.attr,
NULL
};
ATTRIBUTE_GROUPS(drm_privacy_screen);
static struct device_type drm_privacy_screen_type = {
.name = "privacy_screen",
.groups = drm_privacy_screen_groups,
};
static void drm_privacy_screen_device_release(struct device *dev)
{
struct drm_privacy_screen *priv = to_drm_privacy_screen(dev);
kfree(priv);
}
/**
* drm_privacy_screen_register - register a privacy-screen
* @parent: parent-device for the privacy-screen
* @ops: &struct drm_privacy_screen_ops pointer with ops for the privacy-screen
* @data: Private data owned by the privacy screen provider
*
* Create and register a privacy-screen.
*
* Return:
* * A pointer to the created privacy-screen on success.
* * An ERR_PTR(errno) on failure.
*/
struct drm_privacy_screen *drm_privacy_screen_register(
struct device *parent, const struct drm_privacy_screen_ops *ops,
void *data)
{
struct drm_privacy_screen *priv;
int ret;
priv = kzalloc(sizeof(*priv), GFP_KERNEL);
if (!priv)
return ERR_PTR(-ENOMEM);
mutex_init(&priv->lock);
BLOCKING_INIT_NOTIFIER_HEAD(&priv->notifier_head);
priv->dev.class = drm_class;
priv->dev.type = &drm_privacy_screen_type;
priv->dev.parent = parent;
priv->dev.release = drm_privacy_screen_device_release;
dev_set_name(&priv->dev, "privacy_screen-%s", dev_name(parent));
priv->drvdata = data;
priv->ops = ops;
priv->ops->get_hw_state(priv);
ret = device_register(&priv->dev);
if (ret) {
put_device(&priv->dev);
return ERR_PTR(ret);
}
mutex_lock(&drm_privacy_screen_devs_lock);
list_add(&priv->list, &drm_privacy_screen_devs);
mutex_unlock(&drm_privacy_screen_devs_lock);
return priv;
}
EXPORT_SYMBOL(drm_privacy_screen_register);
/**
* drm_privacy_screen_unregister - unregister privacy-screen
* @priv: privacy-screen to unregister
*
* Unregister a privacy-screen registered with drm_privacy_screen_register().
* May be called with a NULL or ERR_PTR, in which case it is a no-op.
*/
void drm_privacy_screen_unregister(struct drm_privacy_screen *priv)
{
if (IS_ERR_OR_NULL(priv))
return;
mutex_lock(&drm_privacy_screen_devs_lock);
list_del(&priv->list);
mutex_unlock(&drm_privacy_screen_devs_lock);
mutex_lock(&priv->lock);
priv->drvdata = NULL;
priv->ops = NULL;
mutex_unlock(&priv->lock);
device_unregister(&priv->dev);
}
EXPORT_SYMBOL(drm_privacy_screen_unregister);
/**
* drm_privacy_screen_call_notifier_chain - notify consumers of state change
* @priv: Privacy screen to register the notifier with
*
* A privacy-screen provider driver can call this functions upon external
* changes to the privacy-screen state. E.g. the state may be changed by the
* hardware itself in response to a hotkey press.
* This function must be called without holding the privacy-screen lock.
* the driver must update sw_state and hw_state to reflect the new state before
* calling this function.
* The expected behavior from the driver upon receiving an external state
* change event is: 1. Take the lock; 2. Update sw_state and hw_state;
* 3. Release the lock. 4. Call drm_privacy_screen_call_notifier_chain().
*/
void drm_privacy_screen_call_notifier_chain(struct drm_privacy_screen *priv)
{
blocking_notifier_call_chain(&priv->notifier_head, 0, priv);
}
EXPORT_SYMBOL(drm_privacy_screen_call_notifier_chain);
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