tests/boards: Add mtk_adsp device test

Simple test of device-specific functionality: cpu frequency control
and host interrupts.

Signed-off-by: Andy Ross <andyross@google.com>

tests/boards/mtk_adsp/CMakeLists.txt

@@ -0,0 +1,7 @@
+# SPDX-License-Identifier: Apache-2.0
+
+cmake_minimum_required(VERSION 3.20.0)
+find_package(Zephyr REQUIRED HINTS $ENV{ZEPHYR_BASE})
+project(mtk_adsp)
+
+target_sources(app PRIVATE src/main.c)

tests/boards/mtk_adsp/prj.conf

@@ -0,0 +1 @@
+CONFIG_ZTEST=y

tests/boards/mtk_adsp/src/main.c

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+/* Copyright 2023 The ChromiumOS Authors
+ * SPDX-License-Identifier: Apache-2.0
+ */
+#include <stdlib.h>
+#include <zephyr/kernel.h>
+#include <zephyr/ztest.h>
+#include <soc.h>
+
+/* Simple test of SOC-specific hardware on the MediaTek Audio DSP
+ * family.  Right now just CPU speed and host mailbox interrupts.
+ */
+
+#define NOM_HZ CONFIG_SYS_CLOCK_HW_CYCLES_PER_SEC
+
+static uint32_t ccount(void)
+{
+	uint32_t t;
+
+	__asm__ volatile("rsr %0, CCOUNT" : "=r"(t));
+	return t;
+}
+
+static uint32_t cpu_hz(void)
+{
+	uint32_t t0 = k_cycle_get_32(), cc0 = ccount();
+
+	k_msleep(100);
+
+	uint32_t t1 = k_cycle_get_32(), cc1 = ccount();
+	uint32_t hz = ((uint64_t)cc1 - cc0) * NOM_HZ / (t1 - t0);
+
+	printk("(measured %u Hz CPU clock vs. %d Hz timer)\n", hz, NOM_HZ);
+	return hz;
+}
+
+ZTEST(mtk_adsp, cpu_freq)
+{
+	int freqs[] = { 26, 370, 540, 720 };
+
+	for (int i = 0; i < ARRAY_SIZE(freqs); i++) {
+		printk("Checking CPU freq entry %d (expect %d MHz)\n", i, freqs[i]);
+		mtk_adsp_set_cpu_freq(freqs[i]);
+
+		/* Compute error as an inverse, i.e. "one part in":
+		 * 100 means 1% off, 1000 is 0.1%, etc...
+		 */
+		uint32_t hz0 = 1000000 * freqs[i], hz = cpu_hz();
+		int32_t err = hz0 / abs((int32_t)(hz0 - hz));
+
+		zassert_true(err > 200);
+	}
+}
+
+#define MBOX0 DEVICE_DT_GET(DT_INST(0, mediatek_mbox))
+#define MBOX1 DEVICE_DT_GET(DT_INST(1, mediatek_mbox))
+
+K_SEM_DEFINE(mbox_sem, 0, 1);
+static bool mbox1_fired;
+
+static void mbox_fn(const struct device *mbox, void *arg)
+{
+	zassert_equal(mbox, MBOX1);
+	zassert_equal(arg, NULL);
+	mbox1_fired = true;
+	k_sem_give(&mbox_sem);
+}
+
+
+/* Test in/out interrupts from the host.  This relies on a SOF driver
+ * on the host, which has the behavior of "replying" with an interrupt
+ * on mbox1 after receiving a "command" on mbox0 (you can also see it
+ * whine about the invalid IPC message in the kernel logs).  SOF
+ * ignores the message bytes (it uses a DRAM area instead), so we just
+ * write them blindly.  It's only a partial test of the hardware, but
+ * easy to run and exercises the core functionality.
+ *
+ * Note that there's a catch: SOF's "reply" comes after a timeout
+ * (it's an invalid command, afterall) which is 165 seconds!  But the
+ * test does pass.
+ */
+ZTEST(mtk_adsp, mbox)
+{
+	mtk_adsp_mbox_set_handler(MBOX1, 1, mbox_fn, NULL);
+
+	for (int i = 0; i < MTK_ADSP_MBOX_MSG_WORDS; i++) {
+		mtk_adsp_mbox_set_msg(MBOX0, i, 0x01010100 | i);
+	}
+
+	/* First signal the host with a reply on the second channel,
+	 * that effects a reply to anything it thinks it might have
+	 * sent us
+	 */
+	mtk_adsp_mbox_signal(MBOX1, 1);
+
+	mtk_adsp_mbox_signal(MBOX0, 0);
+
+	printk("Waiting for reply from SOF driver, be patient: long timeout...\n");
+	k_sem_take(&mbox_sem, K_FOREVER);
+	zassert_true(mbox1_fired);
+}
+
+static void *mtk_adsp_setup(void)
+{
+	return NULL;
+}
+
+ZTEST_SUITE(mtk_adsp, NULL, mtk_adsp_setup, NULL, NULL, NULL);