1#include <linux/export.h>
2#include <linux/list.h>
3#include <linux/of_graph.h>
4#include <drm/drmP.h>
5#include <drm/drm_crtc.h>
6#include <drm/drm_of.h>
7
8/**
9 * drm_crtc_port_mask - find the mask of a registered CRTC by port OF node
10 * @dev: DRM device
11 * @port: port OF node
12 *
13 * Given a port OF node, return the possible mask of the corresponding
14 * CRTC within a device's list of CRTCs.  Returns zero if not found.
15 */
16static uint32_t drm_crtc_port_mask(struct drm_device *dev,
17				   struct device_node *port)
18{
19	unsigned int index = 0;
20	struct drm_crtc *tmp;
21
22	list_for_each_entry(tmp, &dev->mode_config.crtc_list, head) {
23		if (tmp->port == port)
24			return 1 << index;
25
26		index++;
27	}
28
29	return 0;
30}
31
32/**
33 * drm_of_find_possible_crtcs - find the possible CRTCs for an encoder port
34 * @dev: DRM device
35 * @port: encoder port to scan for endpoints
36 *
37 * Scan all endpoints attached to a port, locate their attached CRTCs,
38 * and generate the DRM mask of CRTCs which may be attached to this
39 * encoder.
40 *
41 * See Documentation/devicetree/bindings/graph.txt for the bindings.
42 */
43uint32_t drm_of_find_possible_crtcs(struct drm_device *dev,
44				    struct device_node *port)
45{
46	struct device_node *remote_port, *ep;
47	uint32_t possible_crtcs = 0;
48
49	for_each_endpoint_of_node(port, ep) {
50		remote_port = of_graph_get_remote_port(ep);
51		if (!remote_port) {
52			of_node_put(ep);
53			return 0;
54		}
55
56		possible_crtcs |= drm_crtc_port_mask(dev, remote_port);
57
58		of_node_put(remote_port);
59	}
60
61	return possible_crtcs;
62}
63EXPORT_SYMBOL(drm_of_find_possible_crtcs);
64