common: Migrate online calibration to own module

This change moves the code that handles caching the temperature
(which is the first step in online calibration) into a new
compilational unit.

TEST=None
BRANCH=None
BUG=b:138303429,chromium:1023858

Change-Id: Ib1fe3d2234dc2436e2bbfd4febd22196e5cdafef
Signed-off-by: Yuval Peress <peress@chromium.org>
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform/ec/+/1906340
Reviewed-by: Jack Rosenthal <jrosenth@chromium.org>

1 files changed, 73 insertions, 0 deletions

diff --git a/common/online_calibration.c b/common/online_calibration.c
new file mode 100644
index 0000000000..5626a70107
--- /dev/null
+++ b/common/online_calibration.c
@@ -0,0 +1,73 @@
+/* Copyright 2020 The Chromium OS Authors. All rights reserved.
+ * Use of this source code is governed by a BSD-style license that can be
+ * found in the LICENSE file.
+ */
+
+#include "accelgyro.h"
+#include "hwtimer.h"
+#include "online_calibration.h"
+#include "common.h"
+
+/** Entry of the temperature cache */
+struct temp_cache_entry {
+	/** The temperature that's cached (-1 if invalid) */
+	int temp;
+	/** The timestamp at which the temperature was cached */
+	uint32_t timestamp;
+};
+
+/** Cache for internal sensor temperatures. */
+static struct temp_cache_entry sensor_temp_cache[SENSOR_COUNT];
+
+static int get_temperature(struct motion_sensor_t *sensor, int *temp)
+{
+	struct temp_cache_entry *entry =
+		&sensor_temp_cache[motion_sensors - sensor];
+	uint32_t now;
+
+	if (sensor->drv->read_temp == NULL)
+		return EC_ERROR_UNIMPLEMENTED;
+
+	now = __hw_clock_source_read();
+	if (entry->temp < 0 ||
+	    time_until(entry->timestamp, now) > CONFIG_TEMP_CACHE_STALE_THRES) {
+		int t;
+		int rc = sensor->drv->read_temp(sensor, &t);
+
+		if (rc == EC_SUCCESS) {
+			entry->temp = t;
+			entry->timestamp = now;
+		} else {
+			return rc;
+		}
+	}
+
+	*temp = entry->temp;
+	return EC_SUCCESS;
+}
+
+void online_calibration_init(void)
+{
+	size_t i;
+
+	for (i = 0; i < ARRAY_SIZE(sensor_temp_cache); i++)
+		sensor_temp_cache[i].temp = -1;
+}
+
+int online_calibration_process_data(
+	struct ec_response_motion_sensor_data *data,
+	struct motion_sensor_t *sensor,
+	uint32_t timestamp)
+{
+	int rc;
+	int temperature;
+
+	rc = get_temperature(sensor, &temperature);
+	/*
+	 * TODO actual implementation will come in following CLs.
+	 * The goal of this change is to establish the interface of
+	 * online calibration with the rest of the code base.
+	 */
+	return rc;
+}
+