1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3 * PCM DRM helpers
4 */
5 #include <linux/bitfield.h>
6 #include <linux/export.h>
7 #include <linux/hdmi.h>
8 #include <drm/drm_edid.h>
9 #include <sound/pcm.h>
10 #include <sound/pcm_drm_eld.h>
11
12 #define SAD0_CHANNELS_MASK GENMASK(2, 0) /* max number of channels - 1 */
13 #define SAD0_FORMAT_MASK GENMASK(6, 3) /* audio format */
14
15 #define SAD1_RATE_MASK GENMASK(6, 0) /* bitfield of supported rates */
16 #define SAD1_RATE_32000_MASK BIT(0)
17 #define SAD1_RATE_44100_MASK BIT(1)
18 #define SAD1_RATE_48000_MASK BIT(2)
19 #define SAD1_RATE_88200_MASK BIT(3)
20 #define SAD1_RATE_96000_MASK BIT(4)
21 #define SAD1_RATE_176400_MASK BIT(5)
22 #define SAD1_RATE_192000_MASK BIT(6)
23
24 static const unsigned int eld_rates[] = {
25 32000,
26 44100,
27 48000,
28 88200,
29 96000,
30 176400,
31 192000,
32 };
33
map_rate_families(const u8 * sad,unsigned int mask_32000,unsigned int mask_44100,unsigned int mask_48000)34 static unsigned int map_rate_families(const u8 *sad,
35 unsigned int mask_32000,
36 unsigned int mask_44100,
37 unsigned int mask_48000)
38 {
39 unsigned int rate_mask = 0;
40
41 if (sad[1] & SAD1_RATE_32000_MASK)
42 rate_mask |= mask_32000;
43 if (sad[1] & (SAD1_RATE_44100_MASK | SAD1_RATE_88200_MASK | SAD1_RATE_176400_MASK))
44 rate_mask |= mask_44100;
45 if (sad[1] & (SAD1_RATE_48000_MASK | SAD1_RATE_96000_MASK | SAD1_RATE_192000_MASK))
46 rate_mask |= mask_48000;
47 return rate_mask;
48 }
49
sad_rate_mask(const u8 * sad)50 static unsigned int sad_rate_mask(const u8 *sad)
51 {
52 switch (FIELD_GET(SAD0_FORMAT_MASK, sad[0])) {
53 case HDMI_AUDIO_CODING_TYPE_PCM:
54 return sad[1] & SAD1_RATE_MASK;
55 case HDMI_AUDIO_CODING_TYPE_AC3:
56 case HDMI_AUDIO_CODING_TYPE_DTS:
57 return map_rate_families(sad,
58 SAD1_RATE_32000_MASK,
59 SAD1_RATE_44100_MASK,
60 SAD1_RATE_48000_MASK);
61 case HDMI_AUDIO_CODING_TYPE_EAC3:
62 case HDMI_AUDIO_CODING_TYPE_DTS_HD:
63 case HDMI_AUDIO_CODING_TYPE_MLP:
64 return map_rate_families(sad,
65 0,
66 SAD1_RATE_176400_MASK,
67 SAD1_RATE_192000_MASK);
68 default:
69 /* TODO adjust for other compressed formats as well */
70 return sad[1] & SAD1_RATE_MASK;
71 }
72 }
73
sad_max_channels(const u8 * sad)74 static unsigned int sad_max_channels(const u8 *sad)
75 {
76 switch (FIELD_GET(SAD0_FORMAT_MASK, sad[0])) {
77 case HDMI_AUDIO_CODING_TYPE_PCM:
78 return 1 + FIELD_GET(SAD0_CHANNELS_MASK, sad[0]);
79 case HDMI_AUDIO_CODING_TYPE_AC3:
80 case HDMI_AUDIO_CODING_TYPE_DTS:
81 case HDMI_AUDIO_CODING_TYPE_EAC3:
82 return 2;
83 case HDMI_AUDIO_CODING_TYPE_DTS_HD:
84 case HDMI_AUDIO_CODING_TYPE_MLP:
85 return 8;
86 default:
87 /* TODO adjust for other compressed formats as well */
88 return 1 + FIELD_GET(SAD0_CHANNELS_MASK, sad[0]);
89 }
90 }
91
eld_limit_rates(struct snd_pcm_hw_params * params,struct snd_pcm_hw_rule * rule)92 static int eld_limit_rates(struct snd_pcm_hw_params *params,
93 struct snd_pcm_hw_rule *rule)
94 {
95 struct snd_interval *r = hw_param_interval(params, rule->var);
96 const struct snd_interval *c;
97 unsigned int rate_mask = 7, i;
98 const u8 *sad, *eld = rule->private;
99
100 sad = drm_eld_sad(eld);
101 if (sad) {
102 c = hw_param_interval_c(params, SNDRV_PCM_HW_PARAM_CHANNELS);
103
104 for (i = drm_eld_sad_count(eld); i > 0; i--, sad += 3) {
105 unsigned max_channels = sad_max_channels(sad);
106
107 /*
108 * Exclude SADs which do not include the
109 * requested number of channels.
110 */
111 if (c->min <= max_channels)
112 rate_mask |= sad_rate_mask(sad);
113 }
114 }
115
116 return snd_interval_list(r, ARRAY_SIZE(eld_rates), eld_rates,
117 rate_mask);
118 }
119
eld_limit_channels(struct snd_pcm_hw_params * params,struct snd_pcm_hw_rule * rule)120 static int eld_limit_channels(struct snd_pcm_hw_params *params,
121 struct snd_pcm_hw_rule *rule)
122 {
123 struct snd_interval *c = hw_param_interval(params, rule->var);
124 const struct snd_interval *r;
125 struct snd_interval t = { .min = 1, .max = 2, .integer = 1, };
126 unsigned int i;
127 const u8 *sad, *eld = rule->private;
128
129 sad = drm_eld_sad(eld);
130 if (sad) {
131 unsigned int rate_mask = 0;
132
133 /* Convert the rate interval to a mask */
134 r = hw_param_interval_c(params, SNDRV_PCM_HW_PARAM_RATE);
135 for (i = 0; i < ARRAY_SIZE(eld_rates); i++)
136 if (r->min <= eld_rates[i] && r->max >= eld_rates[i])
137 rate_mask |= BIT(i);
138
139 for (i = drm_eld_sad_count(eld); i > 0; i--, sad += 3)
140 if (rate_mask & sad_rate_mask(sad))
141 t.max = max(t.max, sad_max_channels(sad));
142 }
143
144 return snd_interval_refine(c, &t);
145 }
146
snd_pcm_hw_constraint_eld(struct snd_pcm_runtime * runtime,void * eld)147 int snd_pcm_hw_constraint_eld(struct snd_pcm_runtime *runtime, void *eld)
148 {
149 int ret;
150
151 ret = snd_pcm_hw_rule_add(runtime, 0, SNDRV_PCM_HW_PARAM_RATE,
152 eld_limit_rates, eld,
153 SNDRV_PCM_HW_PARAM_CHANNELS, -1);
154 if (ret < 0)
155 return ret;
156
157 ret = snd_pcm_hw_rule_add(runtime, 0, SNDRV_PCM_HW_PARAM_CHANNELS,
158 eld_limit_channels, eld,
159 SNDRV_PCM_HW_PARAM_RATE, -1);
160
161 return ret;
162 }
163 EXPORT_SYMBOL_GPL(snd_pcm_hw_constraint_eld);
164
