linux/drivers/video/backlight/backlight.c
Noralf Trønnes 479da1f538 backlight: Add backlight_device_get_by_name()
Add a way to lookup a backlight device based on its name.
Will be used by a USB display gadget getting the name from configfs.

Signed-off-by: Noralf Trønnes <noralf@tronnes.org>
Reviewed-by: Sam Ravnborg <sam@ravnborg.org>
Reviewed-by: Daniel Thompson <daniel.thompson@linaro.org>
Acked-by: Jingoo Han <jingoohan1@gmail.com>
Signed-off-by: Lee Jones <lee.jones@linaro.org>
2020-05-11 07:39:16 +01:00

730 lines
19 KiB
C

// SPDX-License-Identifier: GPL-2.0-only
/*
* Backlight Lowlevel Control Abstraction
*
* Copyright (C) 2003,2004 Hewlett-Packard Company
*
*/
#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
#include <linux/module.h>
#include <linux/init.h>
#include <linux/device.h>
#include <linux/backlight.h>
#include <linux/notifier.h>
#include <linux/ctype.h>
#include <linux/err.h>
#include <linux/fb.h>
#include <linux/slab.h>
#ifdef CONFIG_PMAC_BACKLIGHT
#include <asm/backlight.h>
#endif
static struct list_head backlight_dev_list;
static struct mutex backlight_dev_list_mutex;
static struct blocking_notifier_head backlight_notifier;
static const char *const backlight_types[] = {
[BACKLIGHT_RAW] = "raw",
[BACKLIGHT_PLATFORM] = "platform",
[BACKLIGHT_FIRMWARE] = "firmware",
};
static const char *const backlight_scale_types[] = {
[BACKLIGHT_SCALE_UNKNOWN] = "unknown",
[BACKLIGHT_SCALE_LINEAR] = "linear",
[BACKLIGHT_SCALE_NON_LINEAR] = "non-linear",
};
#if defined(CONFIG_FB) || (defined(CONFIG_FB_MODULE) && \
defined(CONFIG_BACKLIGHT_CLASS_DEVICE_MODULE))
/* This callback gets called when something important happens inside a
* framebuffer driver. We're looking if that important event is blanking,
* and if it is and necessary, we're switching backlight power as well ...
*/
static int fb_notifier_callback(struct notifier_block *self,
unsigned long event, void *data)
{
struct backlight_device *bd;
struct fb_event *evdata = data;
int node = evdata->info->node;
int fb_blank = 0;
/* If we aren't interested in this event, skip it immediately ... */
if (event != FB_EVENT_BLANK)
return 0;
bd = container_of(self, struct backlight_device, fb_notif);
mutex_lock(&bd->ops_lock);
if (bd->ops)
if (!bd->ops->check_fb ||
bd->ops->check_fb(bd, evdata->info)) {
fb_blank = *(int *)evdata->data;
if (fb_blank == FB_BLANK_UNBLANK &&
!bd->fb_bl_on[node]) {
bd->fb_bl_on[node] = true;
if (!bd->use_count++) {
bd->props.state &= ~BL_CORE_FBBLANK;
bd->props.fb_blank = FB_BLANK_UNBLANK;
backlight_update_status(bd);
}
} else if (fb_blank != FB_BLANK_UNBLANK &&
bd->fb_bl_on[node]) {
bd->fb_bl_on[node] = false;
if (!(--bd->use_count)) {
bd->props.state |= BL_CORE_FBBLANK;
bd->props.fb_blank = fb_blank;
backlight_update_status(bd);
}
}
}
mutex_unlock(&bd->ops_lock);
return 0;
}
static int backlight_register_fb(struct backlight_device *bd)
{
memset(&bd->fb_notif, 0, sizeof(bd->fb_notif));
bd->fb_notif.notifier_call = fb_notifier_callback;
return fb_register_client(&bd->fb_notif);
}
static void backlight_unregister_fb(struct backlight_device *bd)
{
fb_unregister_client(&bd->fb_notif);
}
#else
static inline int backlight_register_fb(struct backlight_device *bd)
{
return 0;
}
static inline void backlight_unregister_fb(struct backlight_device *bd)
{
}
#endif /* CONFIG_FB */
static void backlight_generate_event(struct backlight_device *bd,
enum backlight_update_reason reason)
{
char *envp[2];
switch (reason) {
case BACKLIGHT_UPDATE_SYSFS:
envp[0] = "SOURCE=sysfs";
break;
case BACKLIGHT_UPDATE_HOTKEY:
envp[0] = "SOURCE=hotkey";
break;
default:
envp[0] = "SOURCE=unknown";
break;
}
envp[1] = NULL;
kobject_uevent_env(&bd->dev.kobj, KOBJ_CHANGE, envp);
sysfs_notify(&bd->dev.kobj, NULL, "actual_brightness");
}
static ssize_t bl_power_show(struct device *dev, struct device_attribute *attr,
char *buf)
{
struct backlight_device *bd = to_backlight_device(dev);
return sprintf(buf, "%d\n", bd->props.power);
}
static ssize_t bl_power_store(struct device *dev, struct device_attribute *attr,
const char *buf, size_t count)
{
int rc;
struct backlight_device *bd = to_backlight_device(dev);
unsigned long power, old_power;
rc = kstrtoul(buf, 0, &power);
if (rc)
return rc;
rc = -ENXIO;
mutex_lock(&bd->ops_lock);
if (bd->ops) {
pr_debug("set power to %lu\n", power);
if (bd->props.power != power) {
old_power = bd->props.power;
bd->props.power = power;
rc = backlight_update_status(bd);
if (rc)
bd->props.power = old_power;
else
rc = count;
} else {
rc = count;
}
}
mutex_unlock(&bd->ops_lock);
return rc;
}
static DEVICE_ATTR_RW(bl_power);
static ssize_t brightness_show(struct device *dev,
struct device_attribute *attr, char *buf)
{
struct backlight_device *bd = to_backlight_device(dev);
return sprintf(buf, "%d\n", bd->props.brightness);
}
int backlight_device_set_brightness(struct backlight_device *bd,
unsigned long brightness)
{
int rc = -ENXIO;
mutex_lock(&bd->ops_lock);
if (bd->ops) {
if (brightness > bd->props.max_brightness)
rc = -EINVAL;
else {
pr_debug("set brightness to %lu\n", brightness);
bd->props.brightness = brightness;
rc = backlight_update_status(bd);
}
}
mutex_unlock(&bd->ops_lock);
backlight_generate_event(bd, BACKLIGHT_UPDATE_SYSFS);
return rc;
}
EXPORT_SYMBOL(backlight_device_set_brightness);
static ssize_t brightness_store(struct device *dev,
struct device_attribute *attr, const char *buf, size_t count)
{
int rc;
struct backlight_device *bd = to_backlight_device(dev);
unsigned long brightness;
rc = kstrtoul(buf, 0, &brightness);
if (rc)
return rc;
rc = backlight_device_set_brightness(bd, brightness);
return rc ? rc : count;
}
static DEVICE_ATTR_RW(brightness);
static ssize_t type_show(struct device *dev, struct device_attribute *attr,
char *buf)
{
struct backlight_device *bd = to_backlight_device(dev);
return sprintf(buf, "%s\n", backlight_types[bd->props.type]);
}
static DEVICE_ATTR_RO(type);
static ssize_t max_brightness_show(struct device *dev,
struct device_attribute *attr, char *buf)
{
struct backlight_device *bd = to_backlight_device(dev);
return sprintf(buf, "%d\n", bd->props.max_brightness);
}
static DEVICE_ATTR_RO(max_brightness);
static ssize_t actual_brightness_show(struct device *dev,
struct device_attribute *attr, char *buf)
{
int rc = -ENXIO;
struct backlight_device *bd = to_backlight_device(dev);
mutex_lock(&bd->ops_lock);
if (bd->ops && bd->ops->get_brightness)
rc = sprintf(buf, "%d\n", bd->ops->get_brightness(bd));
else
rc = sprintf(buf, "%d\n", bd->props.brightness);
mutex_unlock(&bd->ops_lock);
return rc;
}
static DEVICE_ATTR_RO(actual_brightness);
static ssize_t scale_show(struct device *dev,
struct device_attribute *attr, char *buf)
{
struct backlight_device *bd = to_backlight_device(dev);
if (WARN_ON(bd->props.scale > BACKLIGHT_SCALE_NON_LINEAR))
return sprintf(buf, "unknown\n");
return sprintf(buf, "%s\n", backlight_scale_types[bd->props.scale]);
}
static DEVICE_ATTR_RO(scale);
static struct class *backlight_class;
#ifdef CONFIG_PM_SLEEP
static int backlight_suspend(struct device *dev)
{
struct backlight_device *bd = to_backlight_device(dev);
mutex_lock(&bd->ops_lock);
if (bd->ops && bd->ops->options & BL_CORE_SUSPENDRESUME) {
bd->props.state |= BL_CORE_SUSPENDED;
backlight_update_status(bd);
}
mutex_unlock(&bd->ops_lock);
return 0;
}
static int backlight_resume(struct device *dev)
{
struct backlight_device *bd = to_backlight_device(dev);
mutex_lock(&bd->ops_lock);
if (bd->ops && bd->ops->options & BL_CORE_SUSPENDRESUME) {
bd->props.state &= ~BL_CORE_SUSPENDED;
backlight_update_status(bd);
}
mutex_unlock(&bd->ops_lock);
return 0;
}
#endif
static SIMPLE_DEV_PM_OPS(backlight_class_dev_pm_ops, backlight_suspend,
backlight_resume);
static void bl_device_release(struct device *dev)
{
struct backlight_device *bd = to_backlight_device(dev);
kfree(bd);
}
static struct attribute *bl_device_attrs[] = {
&dev_attr_bl_power.attr,
&dev_attr_brightness.attr,
&dev_attr_actual_brightness.attr,
&dev_attr_max_brightness.attr,
&dev_attr_scale.attr,
&dev_attr_type.attr,
NULL,
};
ATTRIBUTE_GROUPS(bl_device);
/**
* backlight_force_update - tell the backlight subsystem that hardware state
* has changed
* @bd: the backlight device to update
*
* Updates the internal state of the backlight in response to a hardware event,
* and generate a uevent to notify userspace
*/
void backlight_force_update(struct backlight_device *bd,
enum backlight_update_reason reason)
{
mutex_lock(&bd->ops_lock);
if (bd->ops && bd->ops->get_brightness)
bd->props.brightness = bd->ops->get_brightness(bd);
mutex_unlock(&bd->ops_lock);
backlight_generate_event(bd, reason);
}
EXPORT_SYMBOL(backlight_force_update);
/**
* backlight_device_register - create and register a new object of
* backlight_device class.
* @name: the name of the new object(must be the same as the name of the
* respective framebuffer device).
* @parent: a pointer to the parent device
* @devdata: an optional pointer to be stored for private driver use. The
* methods may retrieve it by using bl_get_data(bd).
* @ops: the backlight operations structure.
*
* Creates and registers new backlight device. Returns either an
* ERR_PTR() or a pointer to the newly allocated device.
*/
struct backlight_device *backlight_device_register(const char *name,
struct device *parent, void *devdata, const struct backlight_ops *ops,
const struct backlight_properties *props)
{
struct backlight_device *new_bd;
int rc;
pr_debug("backlight_device_register: name=%s\n", name);
new_bd = kzalloc(sizeof(struct backlight_device), GFP_KERNEL);
if (!new_bd)
return ERR_PTR(-ENOMEM);
mutex_init(&new_bd->update_lock);
mutex_init(&new_bd->ops_lock);
new_bd->dev.class = backlight_class;
new_bd->dev.parent = parent;
new_bd->dev.release = bl_device_release;
dev_set_name(&new_bd->dev, "%s", name);
dev_set_drvdata(&new_bd->dev, devdata);
/* Set default properties */
if (props) {
memcpy(&new_bd->props, props,
sizeof(struct backlight_properties));
if (props->type <= 0 || props->type >= BACKLIGHT_TYPE_MAX) {
WARN(1, "%s: invalid backlight type", name);
new_bd->props.type = BACKLIGHT_RAW;
}
} else {
new_bd->props.type = BACKLIGHT_RAW;
}
rc = device_register(&new_bd->dev);
if (rc) {
put_device(&new_bd->dev);
return ERR_PTR(rc);
}
rc = backlight_register_fb(new_bd);
if (rc) {
device_unregister(&new_bd->dev);
return ERR_PTR(rc);
}
new_bd->ops = ops;
#ifdef CONFIG_PMAC_BACKLIGHT
mutex_lock(&pmac_backlight_mutex);
if (!pmac_backlight)
pmac_backlight = new_bd;
mutex_unlock(&pmac_backlight_mutex);
#endif
mutex_lock(&backlight_dev_list_mutex);
list_add(&new_bd->entry, &backlight_dev_list);
mutex_unlock(&backlight_dev_list_mutex);
blocking_notifier_call_chain(&backlight_notifier,
BACKLIGHT_REGISTERED, new_bd);
return new_bd;
}
EXPORT_SYMBOL(backlight_device_register);
struct backlight_device *backlight_device_get_by_type(enum backlight_type type)
{
bool found = false;
struct backlight_device *bd;
mutex_lock(&backlight_dev_list_mutex);
list_for_each_entry(bd, &backlight_dev_list, entry) {
if (bd->props.type == type) {
found = true;
break;
}
}
mutex_unlock(&backlight_dev_list_mutex);
return found ? bd : NULL;
}
EXPORT_SYMBOL(backlight_device_get_by_type);
/**
* backlight_device_get_by_name - Get backlight device by name
* @name: Device name
*
* This function looks up a backlight device by its name. It obtains a reference
* on the backlight device and it is the caller's responsibility to drop the
* reference by calling backlight_put().
*
* Returns:
* A pointer to the backlight device if found, otherwise NULL.
*/
struct backlight_device *backlight_device_get_by_name(const char *name)
{
struct device *dev;
dev = class_find_device_by_name(backlight_class, name);
return dev ? to_backlight_device(dev) : NULL;
}
EXPORT_SYMBOL(backlight_device_get_by_name);
/**
* backlight_device_unregister - unregisters a backlight device object.
* @bd: the backlight device object to be unregistered and freed.
*
* Unregisters a previously registered via backlight_device_register object.
*/
void backlight_device_unregister(struct backlight_device *bd)
{
if (!bd)
return;
mutex_lock(&backlight_dev_list_mutex);
list_del(&bd->entry);
mutex_unlock(&backlight_dev_list_mutex);
#ifdef CONFIG_PMAC_BACKLIGHT
mutex_lock(&pmac_backlight_mutex);
if (pmac_backlight == bd)
pmac_backlight = NULL;
mutex_unlock(&pmac_backlight_mutex);
#endif
blocking_notifier_call_chain(&backlight_notifier,
BACKLIGHT_UNREGISTERED, bd);
mutex_lock(&bd->ops_lock);
bd->ops = NULL;
mutex_unlock(&bd->ops_lock);
backlight_unregister_fb(bd);
device_unregister(&bd->dev);
}
EXPORT_SYMBOL(backlight_device_unregister);
static void devm_backlight_device_release(struct device *dev, void *res)
{
struct backlight_device *backlight = *(struct backlight_device **)res;
backlight_device_unregister(backlight);
}
static int devm_backlight_device_match(struct device *dev, void *res,
void *data)
{
struct backlight_device **r = res;
return *r == data;
}
/**
* backlight_register_notifier - get notified of backlight (un)registration
* @nb: notifier block with the notifier to call on backlight (un)registration
*
* @return 0 on success, otherwise a negative error code
*
* Register a notifier to get notified when backlight devices get registered
* or unregistered.
*/
int backlight_register_notifier(struct notifier_block *nb)
{
return blocking_notifier_chain_register(&backlight_notifier, nb);
}
EXPORT_SYMBOL(backlight_register_notifier);
/**
* backlight_unregister_notifier - unregister a backlight notifier
* @nb: notifier block to unregister
*
* @return 0 on success, otherwise a negative error code
*
* Register a notifier to get notified when backlight devices get registered
* or unregistered.
*/
int backlight_unregister_notifier(struct notifier_block *nb)
{
return blocking_notifier_chain_unregister(&backlight_notifier, nb);
}
EXPORT_SYMBOL(backlight_unregister_notifier);
/**
* devm_backlight_device_register - resource managed backlight_device_register()
* @dev: the device to register
* @name: the name of the device
* @parent: a pointer to the parent device
* @devdata: an optional pointer to be stored for private driver use
* @ops: the backlight operations structure
* @props: the backlight properties
*
* @return a struct backlight on success, or an ERR_PTR on error
*
* Managed backlight_device_register(). The backlight_device returned
* from this function are automatically freed on driver detach.
* See backlight_device_register() for more information.
*/
struct backlight_device *devm_backlight_device_register(struct device *dev,
const char *name, struct device *parent, void *devdata,
const struct backlight_ops *ops,
const struct backlight_properties *props)
{
struct backlight_device **ptr, *backlight;
ptr = devres_alloc(devm_backlight_device_release, sizeof(*ptr),
GFP_KERNEL);
if (!ptr)
return ERR_PTR(-ENOMEM);
backlight = backlight_device_register(name, parent, devdata, ops,
props);
if (!IS_ERR(backlight)) {
*ptr = backlight;
devres_add(dev, ptr);
} else {
devres_free(ptr);
}
return backlight;
}
EXPORT_SYMBOL(devm_backlight_device_register);
/**
* devm_backlight_device_unregister - resource managed backlight_device_unregister()
* @dev: the device to unregister
* @bd: the backlight device to unregister
*
* Deallocated a backlight allocated with devm_backlight_device_register().
* Normally this function will not need to be called and the resource management
* code will ensure that the resource is freed.
*/
void devm_backlight_device_unregister(struct device *dev,
struct backlight_device *bd)
{
int rc;
rc = devres_release(dev, devm_backlight_device_release,
devm_backlight_device_match, bd);
WARN_ON(rc);
}
EXPORT_SYMBOL(devm_backlight_device_unregister);
#ifdef CONFIG_OF
static int of_parent_match(struct device *dev, const void *data)
{
return dev->parent && dev->parent->of_node == data;
}
/**
* of_find_backlight_by_node() - find backlight device by device-tree node
* @node: device-tree node of the backlight device
*
* Returns a pointer to the backlight device corresponding to the given DT
* node or NULL if no such backlight device exists or if the device hasn't
* been probed yet.
*
* This function obtains a reference on the backlight device and it is the
* caller's responsibility to drop the reference by calling put_device() on
* the backlight device's .dev field.
*/
struct backlight_device *of_find_backlight_by_node(struct device_node *node)
{
struct device *dev;
dev = class_find_device(backlight_class, NULL, node, of_parent_match);
return dev ? to_backlight_device(dev) : NULL;
}
EXPORT_SYMBOL(of_find_backlight_by_node);
#endif
/**
* of_find_backlight - Get backlight device
* @dev: Device
*
* This function looks for a property named 'backlight' on the DT node
* connected to @dev and looks up the backlight device.
*
* Call backlight_put() to drop the reference on the backlight device.
*
* Returns:
* A pointer to the backlight device if found.
* Error pointer -EPROBE_DEFER if the DT property is set, but no backlight
* device is found.
* NULL if there's no backlight property.
*/
struct backlight_device *of_find_backlight(struct device *dev)
{
struct backlight_device *bd = NULL;
struct device_node *np;
if (!dev)
return NULL;
if (IS_ENABLED(CONFIG_OF) && dev->of_node) {
np = of_parse_phandle(dev->of_node, "backlight", 0);
if (np) {
bd = of_find_backlight_by_node(np);
of_node_put(np);
if (!bd)
return ERR_PTR(-EPROBE_DEFER);
/*
* Note: gpio_backlight uses brightness as
* power state during probe
*/
if (!bd->props.brightness)
bd->props.brightness = bd->props.max_brightness;
}
}
return bd;
}
EXPORT_SYMBOL(of_find_backlight);
static void devm_backlight_release(void *data)
{
backlight_put(data);
}
/**
* devm_of_find_backlight - Resource-managed of_find_backlight()
* @dev: Device
*
* Device managed version of of_find_backlight().
* The reference on the backlight device is automatically
* dropped on driver detach.
*/
struct backlight_device *devm_of_find_backlight(struct device *dev)
{
struct backlight_device *bd;
int ret;
bd = of_find_backlight(dev);
if (IS_ERR_OR_NULL(bd))
return bd;
ret = devm_add_action(dev, devm_backlight_release, bd);
if (ret) {
backlight_put(bd);
return ERR_PTR(ret);
}
return bd;
}
EXPORT_SYMBOL(devm_of_find_backlight);
static void __exit backlight_class_exit(void)
{
class_destroy(backlight_class);
}
static int __init backlight_class_init(void)
{
backlight_class = class_create(THIS_MODULE, "backlight");
if (IS_ERR(backlight_class)) {
pr_warn("Unable to create backlight class; errno = %ld\n",
PTR_ERR(backlight_class));
return PTR_ERR(backlight_class);
}
backlight_class->dev_groups = bl_device_groups;
backlight_class->pm = &backlight_class_dev_pm_ops;
INIT_LIST_HEAD(&backlight_dev_list);
mutex_init(&backlight_dev_list_mutex);
BLOCKING_INIT_NOTIFIER_HEAD(&backlight_notifier);
return 0;
}
/*
* if this is compiled into the kernel, we need to ensure that the
* class is registered before users of the class try to register lcd's
*/
postcore_initcall(backlight_class_init);
module_exit(backlight_class_exit);
MODULE_LICENSE("GPL");
MODULE_AUTHOR("Jamey Hicks <jamey.hicks@hp.com>, Andrew Zabolotny <zap@homelink.ru>");
MODULE_DESCRIPTION("Backlight Lowlevel Control Abstraction");