1 files changed, 22 insertions, 0 deletions
diff --git a/src/samd21/gpio.c b/src/samd21/gpio.c
new file mode 100644
index 00000000..3ae51f74
--- /dev/null
+++ b/src/samd21/gpio.c
@@ -0,0 +1,22 @@
+// samd21 gpio functions
+//
+// Copyright (C) 2018  Kevin O'Connor <kevin@koconnor.net>
+//
+// This file may be distributed under the terms of the GNU GPLv3 license.
+
+#include "internal.h" // gpio_peripheral
+#include "samd21.h" // PORT
+
+void
+gpio_peripheral(char bank, uint32_t bit, char ptype, uint32_t pull_up)
+{
+    int group = bank == 'A' ? 0 : 1;
+    PortGroup *pg = &PORT->Group[group];
+    if (ptype) {
+        volatile uint8_t *pmux = &pg->PMUX[bit/2].reg;
+        uint8_t shift = (bit & 1) ? 4 : 0, mask = ~(0xf << shift);
+        *pmux = (*pmux & mask) | ((ptype - 'A') << shift);
+    }
+    pg->PINCFG[bit].reg = ((ptype ? PORT_PINCFG_PMUXEN : 0)
+                           | (pull_up ? PORT_PINCFG_PULLEN : 0));
+}