selftests: ALSA: Add test for the 'pcmtest' driver

This test covers the new Virtual PCM Test Driver, including the capturing,
playback and ioctl redefinition functionalities for both interleaved and
non-interleaved access modes. This test is also helpful as an usage example
of the 'pcmtest' driver.

We have a lot of different virtual media drivers, which can be used for
testing of the userspace applications and media subsystem middle layer.
However, all of them are aimed at testing the video functionality and
simulating the video devices. For audio devices we have only snd-dummy
module, which is good in simulating the correct behavior of an ALSA device.
I decided to write a tool, which would help to test the userspace ALSA
programs (and the PCM middle layer as well) under unusual circumstances
to figure out how they would behave. So I came up with this Virtual PCM
Test Driver.

This new Virtual PCM Test Driver has several features which can be useful
during the userspace ALSA applications testing/fuzzing, or testing/fuzzing
of the PCM middle layer. Not all of them can be implemented using the
existing virtual drivers (like dummy or loopback). Here is what can this
driver do:

- Simulate both capture and playback processes
- Generate random or pattern-based capture data
- Check the playback stream for containing the looped pattern
- Inject delays into the playback and capturing processes
- Inject errors during the PCM callbacks

Also, this driver can check the playback stream for containing the
predefined pattern, which is used in the corresponding selftest to check
the PCM middle layer data transferring functionality. Additionally, this
driver redefines the default RESET ioctl, and the selftest covers this PCM
API functionality as well.

The driver supports both interleaved and non-interleaved access modes, and
have separate pattern buffers for each channel. The driver supports up to
4 channels and up to 8 substreams.
Signed-off-by: Ivan Orlov <ivan.orlov0322@gmail.com>
Acked-by: Jaroslav Kysela <perex@perex.cz>
Link: https://lore.kernel.org/r/20230606193254.20791-3-ivan.orlov0322@gmail.comSigned-off-by: Takashi Iwai <tiwai@suse.de>

tools/testing/selftests/alsa/Makefile

@@ -12,7 +12,7 @@ LDLIBS+=-lpthread
 
 OVERRIDE_TARGETS = 1
 
-TEST_GEN_PROGS := mixer-test pcm-test
+TEST_GEN_PROGS := mixer-test pcm-test test-pcmtest-driver
 
 TEST_GEN_PROGS_EXTENDED := libatest.so
 

tools/testing/selftests/alsa/test-pcmtest-driver.c

+// SPDX-License-Identifier: GPL-2.0
+/*
+ * This is the test which covers PCM middle layer data transferring using
+ * the virtual pcm test driver (snd-pcmtest).
+ *
+ * Copyright 2023 Ivan Orlov <ivan.orlov0322@gmail.com>
+ */
+#include <string.h>
+#include <alsa/asoundlib.h>
+#include "../kselftest_harness.h"
+
+#define CH_NUM 4
+
+struct pattern_buf {
+	char buf[1024];
+	int len;
+};
+
+struct pattern_buf patterns[CH_NUM];
+
+struct pcmtest_test_params {
+	unsigned long buffer_size;
+	unsigned long period_size;
+	unsigned long channels;
+	unsigned int rate;
+	snd_pcm_access_t access;
+	size_t sec_buf_len;
+	size_t sample_size;
+	int time;
+	snd_pcm_format_t format;
+};
+
+static int read_patterns(void)
+{
+	FILE *fp, *fpl;
+	int i;
+	char pf[64];
+	char plf[64];
+
+	for (i = 0; i < CH_NUM; i++) {
+		sprintf(plf, "/sys/kernel/debug/pcmtest/fill_pattern%d_len", i);
+		fpl = fopen(plf, "r");
+		if (!fpl)
+			return -1;
+		fscanf(fpl, "%u", &patterns[i].len);
+		fclose(fpl);
+
+		sprintf(pf, "/sys/kernel/debug/pcmtest/fill_pattern%d", i);
+		fp = fopen(pf, "r");
+		if (!fp) {
+			fclose(fpl);
+			return -1;
+		}
+		fread(patterns[i].buf, 1, patterns[i].len, fp);
+		fclose(fp);
+	}
+
+	return 0;
+}
+
+static int get_test_results(char *debug_name)
+{
+	int result;
+	FILE *f;
+	char fname[128];
+
+	sprintf(fname, "/sys/kernel/debug/pcmtest/%s", debug_name);
+
+	f = fopen(fname, "r");
+	if (!f) {
+		printf("Failed to open file\n");
+		return -1;
+	}
+	fscanf(f, "%d", &result);
+	fclose(f);
+
+	return result;
+}
+
+static size_t get_sec_buf_len(unsigned int rate, unsigned long channels, snd_pcm_format_t format)
+{
+	return rate * channels * snd_pcm_format_physical_width(format) / 8;
+}
+
+static int setup_handle(snd_pcm_t **handle, snd_pcm_sw_params_t *swparams,
+			snd_pcm_hw_params_t *hwparams, struct pcmtest_test_params *params,
+			int card, snd_pcm_stream_t stream)
+{
+	char pcm_name[32];
+	int err;
+
+	sprintf(pcm_name, "hw:%d,0,0", card);
+	err = snd_pcm_open(handle, pcm_name, stream, 0);
+	if (err < 0)
+		return err;
+	snd_pcm_hw_params_any(*handle, hwparams);
+	snd_pcm_hw_params_set_rate_resample(*handle, hwparams, 0);
+	snd_pcm_hw_params_set_access(*handle, hwparams, params->access);
+	snd_pcm_hw_params_set_format(*handle, hwparams, params->format);
+	snd_pcm_hw_params_set_channels(*handle, hwparams, params->channels);
+	snd_pcm_hw_params_set_rate_near(*handle, hwparams, &params->rate, 0);
+	snd_pcm_hw_params_set_period_size_near(*handle, hwparams, &params->period_size, 0);
+	snd_pcm_hw_params_set_buffer_size_near(*handle, hwparams, &params->buffer_size);
+	snd_pcm_hw_params(*handle, hwparams);
+	snd_pcm_sw_params_current(*handle, swparams);
+
+	snd_pcm_hw_params_set_rate_resample(*handle, hwparams, 0);
+	snd_pcm_sw_params_set_avail_min(*handle, swparams, params->period_size);
+	snd_pcm_hw_params_set_buffer_size_near(*handle, hwparams, &params->buffer_size);
+	snd_pcm_hw_params_set_period_size_near(*handle, hwparams, &params->period_size, 0);
+	snd_pcm_sw_params(*handle, swparams);
+	snd_pcm_hw_params(*handle, hwparams);
+
+	return 0;
+}
+
+FIXTURE(pcmtest) {
+	int card;
+	snd_pcm_sw_params_t *swparams;
+	snd_pcm_hw_params_t *hwparams;
+	struct pcmtest_test_params params;
+};
+
+FIXTURE_TEARDOWN(pcmtest) {
+}
+
+FIXTURE_SETUP(pcmtest) {
+	char *card_name;
+	int err;
+
+	if (geteuid())
+		SKIP(exit(-1), "This test needs root to run!");
+
+	err = read_patterns();
+	if (err)
+		SKIP(exit(-1), "Can't read patterns. Probably, module isn't loaded");
+
+	card_name = malloc(127);
+	ASSERT_NE(card_name, NULL);
+	self->params.buffer_size = 16384;
+	self->params.period_size = 4096;
+	self->params.channels = CH_NUM;
+	self->params.rate = 8000;
+	self->params.access = SND_PCM_ACCESS_RW_INTERLEAVED;
+	self->params.format = SND_PCM_FORMAT_S16_LE;
+	self->card = -1;
+	self->params.sample_size = snd_pcm_format_physical_width(self->params.format) / 8;
+
+	self->params.sec_buf_len = get_sec_buf_len(self->params.rate, self->params.channels,
+						   self->params.format);
+	self->params.time = 4;
+
+	while (snd_card_next(&self->card) >= 0) {
+		if (self->card == -1)
+			break;
+		snd_card_get_name(self->card, &card_name);
+		if (!strcmp(card_name, "PCM-Test"))
+			break;
+	}
+	free(card_name);
+	ASSERT_NE(self->card, -1);
+}
+
+/*
+ * Here we are trying to send the looped monotonically increasing sequence of bytes to the driver.
+ * If our data isn't corrupted, the driver will set the content of 'pc_test' debugfs file to '1'
+ */
+TEST_F(pcmtest, playback) {
+	snd_pcm_t *handle;
+	unsigned char *it;
+	size_t write_res;
+	int test_results;
+	int i, cur_ch, pos_in_ch;
+	void *samples;
+	struct pcmtest_test_params *params = &self->params;
+
+	samples = calloc(self->params.sec_buf_len * self->params.time, 1);
+	ASSERT_NE(samples, NULL);
+
+	snd_pcm_sw_params_alloca(&self->swparams);
+	snd_pcm_hw_params_alloca(&self->hwparams);
+
+	ASSERT_EQ(setup_handle(&handle, self->swparams, self->hwparams, params,
+			       self->card, SND_PCM_STREAM_PLAYBACK), 0);
+	snd_pcm_format_set_silence(params->format, samples,
+				   params->rate * params->channels * params->time);
+	it = samples;
+	for (i = 0; i < self->params.sec_buf_len * params->time; i++) {
+		cur_ch = (i / params->sample_size) % CH_NUM;
+		pos_in_ch = i / params->sample_size / CH_NUM * params->sample_size
+			    + (i % params->sample_size);
+		it[i] = patterns[cur_ch].buf[pos_in_ch % patterns[cur_ch].len];
+	}
+	write_res = snd_pcm_writei(handle, samples, params->rate * params->time);
+	ASSERT_GE(write_res, 0);
+
+	snd_pcm_close(handle);
+	free(samples);
+	test_results = get_test_results("pc_test");
+	ASSERT_EQ(test_results, 1);
+}
+
+/*
+ * Here we test that the virtual alsa driver returns looped and monotonically increasing sequence
+ * of bytes. In the interleaved mode the buffer will contain samples in the following order:
+ * C0, C1, C2, C3, C0, C1, ...
+ */
+TEST_F(pcmtest, capture) {
+	snd_pcm_t *handle;
+	unsigned char *it;
+	size_t read_res;
+	int i, cur_ch, pos_in_ch;
+	void *samples;
+	struct pcmtest_test_params *params = &self->params;
+
+	samples = calloc(self->params.sec_buf_len * self->params.time, 1);
+	ASSERT_NE(samples, NULL);
+
+	snd_pcm_sw_params_alloca(&self->swparams);
+	snd_pcm_hw_params_alloca(&self->hwparams);
+
+	ASSERT_EQ(setup_handle(&handle, self->swparams, self->hwparams,
+			       params, self->card, SND_PCM_STREAM_CAPTURE), 0);
+	snd_pcm_format_set_silence(params->format, samples,
+				   params->rate * params->channels * params->time);
+	read_res = snd_pcm_readi(handle, samples, params->rate * params->time);
+	ASSERT_GE(read_res, 0);
+	snd_pcm_close(handle);
+	it = (unsigned char *)samples;
+	for (i = 0; i < self->params.sec_buf_len * self->params.time; i++) {
+		cur_ch = (i / params->sample_size) % CH_NUM;
+		pos_in_ch = i / params->sample_size / CH_NUM * params->sample_size
+			    + (i % params->sample_size);
+		ASSERT_EQ(it[i], patterns[cur_ch].buf[pos_in_ch % patterns[cur_ch].len]);
+	}
+	free(samples);
+}
+
+// Test capture in the non-interleaved access mode. The are buffers for each recorded channel
+TEST_F(pcmtest, ni_capture) {
+	snd_pcm_t *handle;
+	struct pcmtest_test_params params = self->params;
+	char **chan_samples;
+	size_t i, j, read_res;
+
+	chan_samples = calloc(CH_NUM, sizeof(*chan_samples));
+	ASSERT_NE(chan_samples, NULL);
+
+	snd_pcm_sw_params_alloca(&self->swparams);
+	snd_pcm_hw_params_alloca(&self->hwparams);
+
+	params.access = SND_PCM_ACCESS_RW_NONINTERLEAVED;
+
+	ASSERT_EQ(setup_handle(&handle, self->swparams, self->hwparams,
+			       &params, self->card, SND_PCM_STREAM_CAPTURE), 0);
+
+	for (i = 0; i < CH_NUM; i++)
+		chan_samples[i] = calloc(params.sec_buf_len * params.time, 1);
+
+	for (i = 0; i < 1; i++) {
+		read_res = snd_pcm_readn(handle, (void **)chan_samples, params.rate * params.time);
+		ASSERT_GE(read_res, 0);
+	}
+	snd_pcm_close(handle);
+
+	for (i = 0; i < CH_NUM; i++) {
+		for (j = 0; j < params.rate * params.time; j++)
+			ASSERT_EQ(chan_samples[i][j], patterns[i].buf[j % patterns[i].len]);
+		free(chan_samples[i]);
+	}
+	free(chan_samples);
+}
+
+TEST_F(pcmtest, ni_playback) {
+	snd_pcm_t *handle;
+	struct pcmtest_test_params params = self->params;
+	char **chan_samples;
+	size_t i, j, read_res;
+	int test_res;
+
+	chan_samples = calloc(CH_NUM, sizeof(*chan_samples));
+	ASSERT_NE(chan_samples, NULL);
+
+	snd_pcm_sw_params_alloca(&self->swparams);
+	snd_pcm_hw_params_alloca(&self->hwparams);
+
+	params.access = SND_PCM_ACCESS_RW_NONINTERLEAVED;
+
+	ASSERT_EQ(setup_handle(&handle, self->swparams, self->hwparams,
+			       &params, self->card, SND_PCM_STREAM_PLAYBACK), 0);
+
+	for (i = 0; i < CH_NUM; i++) {
+		chan_samples[i] = calloc(params.sec_buf_len * params.time, 1);
+		for (j = 0; j < params.sec_buf_len * params.time; j++)
+			chan_samples[i][j] = patterns[i].buf[j % patterns[i].len];
+	}
+
+	for (i = 0; i < 1; i++) {
+		read_res = snd_pcm_writen(handle, (void **)chan_samples, params.rate * params.time);
+		ASSERT_GE(read_res, 0);
+	}
+
+	snd_pcm_close(handle);
+	test_res = get_test_results("pc_test");
+	ASSERT_EQ(test_res, 1);
+
+	for (i = 0; i < CH_NUM; i++)
+		free(chan_samples[i]);
+	free(chan_samples);
+}
+
+/*
+ * Here we are testing the custom ioctl definition inside the virtual driver. If it triggers
+ * successfully, the driver sets the content of 'ioctl_test' debugfs file to '1'.
+ */
+TEST_F(pcmtest, reset_ioctl) {
+	snd_pcm_t *handle;
+	unsigned char *it;
+	int test_res;
+	struct pcmtest_test_params *params = &self->params;
+
+	snd_pcm_sw_params_alloca(&self->swparams);
+	snd_pcm_hw_params_alloca(&self->hwparams);
+
+	ASSERT_EQ(setup_handle(&handle, self->swparams, self->hwparams, params,
+			       self->card, SND_PCM_STREAM_CAPTURE), 0);
+	snd_pcm_reset(handle);
+	test_res = get_test_results("ioctl_test");
+	ASSERT_EQ(test_res, 1);
+	snd_pcm_close(handle);
+}
+
+TEST_HARNESS_MAIN