stm32f0: timers: input capture support rising/falling edges

This is common code for f0234, keep renaming files as has become standard, even
if it's a suboptimal solution.  This doesn't rename the header which was not
renamed for f3.

Reported-by: https://github.com/gtoonstra

lib/stm32/common/timer_common_f0234.c

@@ -0,0 +1,58 @@
+/** @addtogroup timer_file
+
+*/
+
+/*
+ * This file is part of the libopencm3 project.
+ *
+ * Copyright (C) 2010 Edward Cheeseman <evbuilder@users.sourceforge.org>
+ * Copyright (C) 2011 Stephen Caudle <scaudle@doceme.com>
+ *
+ * This library is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Lesser General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This library 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 Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public License
+ * along with this library.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+/**@{*/
+
+#include <libopencm3/stm32/timer.h>
+
+/*---------------------------------------------------------------------------*/
+/** @brief Set Input Polarity
+
+The timer channel must be set to input capture mode.
+
+@param[in] timer_peripheral Unsigned int32. Timer register address base
+@param[in] ic ::tim_ic_id. Input Capture channel designator.
+@param[in] pol ::tim_ic_pol. Input Capture polarity control.
+*/
+
+void timer_ic_set_polarity(uint32_t timer_peripheral, enum tim_ic_id ic,
+			   enum tim_ic_pol pol)
+{
+	/* Clear CCxP and CCxNP to zero. For both edge trigger both fields are
+	 * set. Case 10 is invalid.
+	 */
+	TIM_CCER(timer_peripheral) &= ~(0xa << (ic * 4));
+	switch (pol) {
+	case TIM_IC_RISING:  /* 00 */
+		break;
+	case TIM_IC_BOTH:    /* 11 */
+		TIM_CCER(timer_peripheral) |= (0xa << (ic * 4));
+		break;
+	case TIM_IC_FALLING: /* 01 */
+		TIM_CCER(timer_peripheral) |= (0x2 << (ic * 4));
+	}
+}
+/**@}*/
+
+