--- /dev/null
+/*
+ * Copyright © 2019 Keith Packard <keithp@keithp.com>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 2 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.
+ */
+
+#include <ao.h>
+#include <ao_tc-samd21.h>
+
+void
+ao_tc_set(struct samd21_tc *tc, uint8_t channel, uint32_t value)
+{
+ tc->mode_16.cc[channel] = value;
+}
+
+static void
+ao_tc_init(struct samd21_tc *tc, uint32_t apbcmask)
+{
+ samd21_pm.apbcmask |= apbcmask;
+
+ /* Reset the device */
+ tc->ctrla = (1 << SAMD21_TC_CTRLA_SWRST);
+
+ while ((tc->ctrla & (1 << SAMD21_TC_CTRLA_SWRST)) != 0 ||
+ (tc->status & (1 << SAMD21_TC_STATUS_SYNCBUSY)) != 0)
+ ;
+
+ tc->ctrla = ((SAMD21_TC_CTRLA_PRESCSYNC_GCLK << SAMD21_TC_CTRLA_PRESCSYNC) |
+ (SAMD21_TC_CTRLA_PRESCALER_DIV1 << SAMD21_TC_CTRLA_PRESCALER) |
+ (SAMD21_TC_CTRLA_WAVEGEN_NPWM << SAMD21_TC_CTRLA_WAVEGEN) |
+ (SAMD21_TC_CTRLA_MODE_COUNT16) |
+ (1 << SAMD21_TC_CTRLA_ENABLE));
+ tc->dbgctrl = (1 << SAMD21_TC_DBGCTRL_DBGRUN);
+}
+
+void
+ao_tc_samd21_init(void)
+{
+ /* SAMD21G18 has only TC3-TC5 */
+ samd21_gclk_clkctrl(0, SAMD21_GCLK_CLKCTRL_ID_TCC2_TC3);
+ samd21_gclk_clkctrl(0, SAMD21_GCLK_CLKCTRL_ID_TC4_TC5);
+
+ ao_tc_init(&samd21_tc3, 1 << SAMD21_PM_APBCMASK_TC3);
+ ao_tc_init(&samd21_tc4, 1 << SAMD21_PM_APBCMASK_TC4);
+ ao_tc_init(&samd21_tc5, 1 << SAMD21_PM_APBCMASK_TC5);
+}