1// SPDX-License-Identifier: GPL-2.0-only
 2/*
 3 *  PCM DRM helpers
 4 */
 5#include <linux/export.h>
 6#include <drm/drm_edid.h>
 7#include <sound/pcm.h>
 8#include <sound/pcm_drm_eld.h>
 9
10static const unsigned int eld_rates[] = {
11	32000,
12	44100,
13	48000,
14	88200,
15	96000,
16	176400,
17	192000,
18};
19
20static unsigned int sad_max_channels(const u8 *sad)
21{
22	return 1 + (sad[0] & 7);
23}
24
25static int eld_limit_rates(struct snd_pcm_hw_params *params,
26			   struct snd_pcm_hw_rule *rule)
27{
28	struct snd_interval *r = hw_param_interval(params, rule->var);
29	const struct snd_interval *c;
30	unsigned int rate_mask = 7, i;
31	const u8 *sad, *eld = rule->private;
32
33	sad = drm_eld_sad(eld);
34	if (sad) {
35		c = hw_param_interval_c(params, SNDRV_PCM_HW_PARAM_CHANNELS);
36
37		for (i = drm_eld_sad_count(eld); i > 0; i--, sad += 3) {
38			unsigned max_channels = sad_max_channels(sad);
39
40			/*
41			 * Exclude SADs which do not include the
42			 * requested number of channels.
43			 */
44			if (c->min <= max_channels)
45				rate_mask |= sad[1];
46		}
47	}
48
49	return snd_interval_list(r, ARRAY_SIZE(eld_rates), eld_rates,
50				 rate_mask);
51}
52
53static int eld_limit_channels(struct snd_pcm_hw_params *params,
54			      struct snd_pcm_hw_rule *rule)
55{
56	struct snd_interval *c = hw_param_interval(params, rule->var);
57	const struct snd_interval *r;
58	struct snd_interval t = { .min = 1, .max = 2, .integer = 1, };
59	unsigned int i;
60	const u8 *sad, *eld = rule->private;
61
62	sad = drm_eld_sad(eld);
63	if (sad) {
64		unsigned int rate_mask = 0;
65
66		/* Convert the rate interval to a mask */
67		r = hw_param_interval_c(params, SNDRV_PCM_HW_PARAM_RATE);
68		for (i = 0; i < ARRAY_SIZE(eld_rates); i++)
69			if (r->min <= eld_rates[i] && r->max >= eld_rates[i])
70				rate_mask |= BIT(i);
71
72		for (i = drm_eld_sad_count(eld); i > 0; i--, sad += 3)
73			if (rate_mask & sad[1])
74				t.max = max(t.max, sad_max_channels(sad));
75	}
76
77	return snd_interval_refine(c, &t);
78}
79
80int snd_pcm_hw_constraint_eld(struct snd_pcm_runtime *runtime, void *eld)
81{
82	int ret;
83
84	ret = snd_pcm_hw_rule_add(runtime, 0, SNDRV_PCM_HW_PARAM_RATE,
85				  eld_limit_rates, eld,
86				  SNDRV_PCM_HW_PARAM_CHANNELS, -1);
87	if (ret < 0)
88		return ret;
89
90	ret = snd_pcm_hw_rule_add(runtime, 0, SNDRV_PCM_HW_PARAM_CHANNELS,
91				  eld_limit_channels, eld,
92				  SNDRV_PCM_HW_PARAM_RATE, -1);
93
94	return ret;
95}
96EXPORT_SYMBOL_GPL(snd_pcm_hw_constraint_eld);