1 files changed, 76 insertions, 0 deletions
diff --git a/src/nvic.c b/src/nvic.c
new file mode 100644
index 0000000..865abf3
--- /dev/null
+++ b/src/nvic.c
@@ -0,0 +1,76 @@
+/*
+ * Copyright (c) 2018 Richard Braun.
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a
+ * copy of this software and associated documentation files (the "Software"),
+ * to deal in the Software without restriction, including without limitation
+ * the rights to use, copy, modify, merge, publish, distribute, sublicense,
+ * and/or sell copies of the Software, and to permit persons to whom the
+ * Software is furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+ * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
+ * DEALINGS IN THE SOFTWARE.
+ */
+
+#include <stdint.h>
+
+#include "cpu.h"
+#include "nvic.h"
+
+#define NVIC_BASE_ADDR 0xe000e100
+
+struct nvic_regs {
+    uint32_t iser[16];
+    uint32_t icer[16];
+    uint32_t ispr[16];
+    uint32_t icpr[16];
+    uint32_t iabr[16];
+    uint32_t reserved[47];
+    uint32_t ipr[124];
+};
+
+static volatile struct nvic_regs *nvic_regs = (void *)NVIC_BASE_ADDR;
+
+static void
+nvic_get_dest(unsigned int irq, volatile uint32_t *array,
+              volatile uint32_t **reg, uint32_t *mask)
+{
+    *reg = &array[irq / 32];
+    *mask = (1 << (irq % 32));
+}
+
+void
+nvic_irq_enable(unsigned int irq)
+{
+    volatile uint32_t *reg;
+    uint32_t mask;
+    uint32_t primask;
+
+    nvic_get_dest(irq, nvic_regs->iser, &reg, &mask);
+
+    primask = cpu_intr_save();
+    *reg |= mask;
+    cpu_intr_restore(primask);
+}
+
+void
+nvic_irq_disable(unsigned int irq)
+{
+    volatile uint32_t *reg;
+    uint32_t mask;
+    uint32_t primask;
+
+    nvic_get_dest(irq, nvic_regs->icer, &reg, &mask);
+
+    primask = cpu_intr_save();
+    *reg |= mask;
+    cpu_intr_restore(primask);
+}