cachepc-linux

Fork of AMDESE/linux with modifications for CachePC side-channel attack
git clone https://git.sinitax.com/sinitax/cachepc-linux
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pcm_drm_eld.c (2319B)

      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);