path: root/drivers/of/dynamic.c

// SPDX-License-Identifier: GPL-2.0
/*
 * Support for dynamic device trees.
 *
 * On some platforms, the device tree can be manipulated at runtime.
 * The routines in this section support adding, removing and changing
 * device tree nodes.
 */

#define pr_fmt(fmt)	"OF: " fmt

#include <linux/cleanup.h>
#include <linux/device.h>
#include <linux/of.h>
#include <linux/spinlock.h>
#include <linux/slab.h>
#include <linux/string.h>
#include <linux/proc_fs.h>

#include "of_private.h"

static struct device_node *kobj_to_device_node(struct kobject *kobj)
{
	return container_of(kobj, struct device_node, kobj);
}

/**
 * of_node_get() - Increment refcount of a node
 * @node:	Node to inc refcount, NULL is supported to simplify writing of
 *		callers
 *
 * Return: The node with refcount incremented.
 */
struct device_node *of_node_get(struct device_node *node)
{
	if (node)
		kobject_get(&node->kobj);
	return node;
}
EXPORT_SYMBOL(of_node_get);

/**
 * of_node_put() - Decrement refcount of a node
 * @node:	Node to dec refcount, NULL is supported to simplify writing of
 *		callers
 */
void of_node_put(struct device_node *node)
{
	if (node)
		kobject_put(&node->kobj);
}
EXPORT_SYMBOL(of_node_put);

static BLOCKING_NOTIFIER_HEAD(of_reconfig_chain);

int of_reconfig_notifier_register(struct notifier_block *nb)
{
	return blocking_notifier_chain_register(&of_reconfig_chain, nb);
}
EXPORT_SYMBOL_GPL(of_reconfig_notifier_register);

int of_reconfig_notifier_unregister(struct notifier_block *nb)
{
	return blocking_notifier_chain_unregister(&of_reconfig_chain, nb);
}
EXPORT_SYMBOL_GPL(of_reconfig_notifier_unregister);

static const char *action_names[] = {
	[0] = "INVALID",
	[OF_RECONFIG_ATTACH_NODE] = "ATTACH_NODE",
	[OF_RECONFIG_DETACH_NODE] = "DETACH_NODE",
	[OF_RECONFIG_ADD_PROPERTY] = "ADD_PROPERTY",
	[OF_RECONFIG_REMOVE_PROPERTY] = "REMOVE_PROPERTY",
	[OF_RECONFIG_UPDATE_PROPERTY] = "UPDATE_PROPERTY",
};

#define _do_print(func, prefix, action, node, prop, ...) ({	\
	func("changeset: " prefix "%-15s %pOF%s%s\n",		\
	     ##__VA_ARGS__, action_names[action], node,		\
	     prop ? ":" : "", prop ? prop->name : "");		\
})
#define of_changeset_action_err(...) _do_print(pr_err, __VA_ARGS__)
#define of_changeset_action_debug(...) _do_print(pr_debug, __VA_ARGS__)

int of_reconfig_notify(unsigned long action, struct of_reconfig_data *p)
{
	int rc;
	struct of_reconfig_data *pr = p;

	of_changeset_action_debug("notify: ", action, pr->dn, pr->prop);

	rc = blocking_notifier_call_chain(&of_reconfig_chain, action, p);
	return notifier_to_errno(rc);
}

/*
 * of_reconfig_get_state_change()	- Returns new state of device
 * @action	- action of the of notifier
 * @arg		- argument of the of notifier
 *
 * Returns the new state of a device based on the notifier used.
 *
 * Return: OF_RECONFIG_CHANGE_REMOVE on device going from enabled to
 * disabled, OF_RECONFIG_CHANGE_ADD on device going from disabled to
 * enabled and OF_RECONFIG_NO_CHANGE on no change.
 */
int of_reconfig_get_state_change(unsigned long action, struct of_reconfig_data *pr)
{
	struct property *prop, *old_prop = NULL;
	int is_status, status_state, old_status_state, prev_state, new_state;

	/* figure out if a device should be created or destroyed */
	switch (action) {
	case OF_RECONFIG_ATTACH_NODE:
	case OF_RECONFIG_DETACH_NODE:
		prop = of_find_property(pr->dn, "status", NULL);
		break;
	case OF_RECONFIG_ADD_PROPERTY:
	case OF_RECONFIG_REMOVE_PROPERTY:
		prop = pr->prop;
		break;
	case OF_RECONFIG_UPDATE_PROPERTY:
		prop = pr->prop;
		old_prop = pr->old_prop;
		break;
	default:
		return OF_RECONFIG_NO_CHANGE;
	}

	is_status = 0;
	status_state = -1;
	old_status_state = -1;
	prev_state = -1;
	new_state = -1;

	if (prop && !strcmp(prop->name, "status")) {
		is_status = 1;
		status_state = !strcmp(prop->value, "okay") ||
			       !strcmp(prop->value, "ok");
		if (old_prop)
			old_status_state = !strcmp(old_prop->value, "okay") ||
					   !strcmp(old_prop->value, "ok");
	}

	switch (action) {
	case OF_RECONFIG_ATTACH_NODE:
		prev_state = 0;
		/* -1 & 0 status either missing or okay */
		new_state = status_state != 0;
		break;
	case OF_RECONFIG_DETACH_NODE:
		/* -1 & 0 status either missing or okay */
		prev_state = status_state != 0;
		new_state = 0;
		break;
	case OF_RECONFIG_ADD_PROPERTY:
		if (is_status) {
			/* no status property -> enabled (legacy) */
			prev_state = 1;
			new_state = status_state;
		}
		break;
	case OF_RECONFIG_REMOVE_PROPERTY:
		if (is_status) {
			prev_state = status_state;
			/* no status property -> enabled (legacy) */
			new_state = 1;
		}
		break;
	case OF_RECONFIG_UPDATE_PROPERTY:
		if (is_status) {
			prev_state = old_status_state != 0;
			new_state = status_state != 0;
		}
		break;
	}

	if (prev_state == new_state)
		return OF_RECONFIG_NO_CHANGE;

	return new_state ? OF_RECONFIG_CHANGE_ADD : OF_RECONFIG_CHANGE_REMOVE;
}
EXPORT_SYMBOL_GPL(of_reconfig_get_state_change);

int of_property_notify(int action, struct device_node *np,
		       struct property *prop, struct property *oldprop)
{
	struct of_reconfig_data pr;

	/* only call notifiers if the node is attached */
	if (!of_node_is_attached(np))
		return 0;

	pr.dn = np;
	pr.prop = prop;
	pr.old_prop = oldprop;
	return of_reconfig_notify(action, &pr