move MS power control handling from sysmobts to common part

MS uplink power control is required in pretty much any BTS, and we
cannot assume that they PHY / L1 will always take care of it by
itself.   So the correspondign code is moved to common/power_control.c
and called from the generic part of L1SAP.

The corresponding VTY paramter has been moved from the sysmobts-specific
trx VTY node to the common BTS VTY node.

1 files changed, 99 insertions, 0 deletions

diff --git a/src/common/power_control.c b/src/common/power_control.c
new file mode 100644
index 00000000..78d2702b
--- /dev/null
+++ b/src/common/power_control.c
@@ -0,0 +1,99 @@
+/* MS Power Control Loop L1 */
+
+/* (C) 2014 by Holger Hans Peter Freyther
+ *
+ * All Rights Reserved
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU Affero General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ *
+ */
+
+#include <stdint.h>
+#include <unistd.h>
+#include <errno.h>
+
+#include <osmo-bts/logging.h>
+#include <osmo-bts/bts.h>
+#include <osmo-bts/gsm_data.h>
+#include <osmo-bts/measurement.h>
+#include <osmo-bts/bts_model.h>
+#include <osmo-bts/l1sap.h>
+
+/*
+ * Check if manual power control is needed
+ * Check if fixed power was selected
+ * Check if the MS is already using our level if not
+ * the value is bogus..
+ * TODO: Add a timeout.. e.g. if the ms is not capable of reaching
+ * the value we have set.
+ */
+int lchan_ms_pwr_ctrl(struct gsm_lchan *lchan,
+		      const uint8_t ms_power, const int rxLevel)
+{
+	int rx;
+	int cur_dBm, new_dBm, new_pwr;
+	struct gsm_bts *bts = lchan->ts->trx->bts;
+	struct gsm_bts_role_bts *btsb = bts_role_bts(bts);
+	const enum gsm_band band = bts->band;
+
+	if (!trx_ms_pwr_ctrl_is_osmo(lchan->ts->trx))
+		return 0;
+	if (lchan->ms_power_ctrl.fixed)
+		return 0;
+
+	/* The phone hasn't reached the power level yet */
+	if (lchan->ms_power_ctrl.current != ms_power)
+		return 0;
+
+	/*
+	 * What is the difference between what we want and received?
+	 * Ignore a margin that is within the range of measurement
+	 * and MS output issues.
+	 */
+	rx = btsb->ul_power_target - rxLevel;
+	if (rx >= 0 && rx < 1)
+		return 0;
+	if (rx < 0 && rx > -1)
+		return 0;
+
+	/* We don't really care about the truncation of int + float */
+	cur_dBm = ms_pwr_dbm(band, ms_power);
+	new_dBm = cur_dBm + rx;
+
+	/* Clamp negative values and do it depending on the band */
+	if (new_dBm < 0)
+		new_dBm = 0;
+
+	switch (band) {
+	case GSM_BAND_1800:
+		/* If MS_TX_PWR_MAX_CCH is set the values 29,
+		 * 30, 31 are not used. Avoid specifying a dBm
+		 * that would lead to these power levels. The
+		 * phone might not be able to reach them. */
+		if (new_dBm > 30)
+			new_dBm = 30;
+		break;
+	default:
+		break;
+	}
+
+	new_pwr = ms_pwr_ctl_lvl(band, new_dBm);
+	if (lchan->ms_power_ctrl.current != new_pwr) {
+		lchan->ms_power_ctrl.current = new_pwr;
+		bts_model_adjst_ms_pwr(lchan);
+		return 1;
+	}
+
+	return 0;
+}