3 files changed, 115 insertions, 0 deletions
diff --git a/src/user/Makefile b/src/user/Makefile
new file mode 100644
index 0000000..d22fbf3
--- /dev/null
+++ b/src/user/Makefile
@@ -0,0 +1,22 @@
+CFILES = $(wildcard *.c)
+AFILES = $(wildcard *.s) 
+OFILES = $(patsubst %.c, %.o, $(CFILES)) \
+	 $(patsubst %.s, %.asm.o, $(AFILES))
+
+CFLAGS += -I.. -I../arch/cmsis
+
+all: $(OFILES)
+
+%.o: %.c
+	@echo "  CC     " $<
+	@$(CROSS)$(CC) $(CFLAGS) -c $< -o $@
+
+%.asm.o: %.s
+	@echo "  AS     " $<
+	@$(CROSS)$(AS) $(AFLAGS) -c $< -o $@
+
+clean:
+	@echo "  CLEAN"
+	@rm -f $(OFILES)
+
+
diff --git a/src/user/priv_gpio.h b/src/user/priv_gpio.h
new file mode 100644
index 0000000..6b349fe
--- /dev/null
+++ b/src/user/priv_gpio.h
@@ -0,0 +1,58 @@
+/**
+ * @file priv_gpio.h
+ * GPIO access for unpriviledged processes
+ *
+ * Copyright (C) 2018 Clyne Sullivan
+ *
+ * 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 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 General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#ifndef PRIV_GPIO_H_
+#define PRIV_GPIO_H_
+
+// For value flags
+#include <kernel/gpio.h>
+
+/**
+ * Possible GPIO calls.
+ */
+enum GPIO_CALLS {
+	GPIO_MODE = 0, /**< Change GPIO mode */
+	GPIO_TYPE, /**< Change GPIO type (PuPd/ODrain) */
+	GPIO_PUPD, /**< Set/clear pullup/pulldown */
+	GPIO_SPEED, /**< Set GPIO speed */
+	GPIO_OUT, /**< Set GPIO output state */
+};
+
+/**
+ * Provides unpriviledged GPIO access.
+ * @param call The type of GPIO call to make
+ * @param pin The pin to modify (0-15 = A, 16-31 = B, ...)
+ * @param value The value to pass to the call
+ */
+void gpio(uint32_t call, uint32_t pin, uint32_t value) 
+{
+	register uint32_t r0 asm("r0") = call;
+	register uint32_t r1 asm("r1") = pin;
+	register uint32_t r2 asm("r2") = value;
+
+	asm("\
+		mov r0, %0; \
+		mov r1, %1; \
+		mov r2, %2; \
+		svc 1; \
+	" :: "r" (r0), "r" (r1), "r" (r2));
+}
+
+#endif // PRIV_GPIO_H_
diff --git a/src/user/user.c b/src/user/user.c
new file mode 100644
index 0000000..fc51d29
--- /dev/null
+++ b/src/user/user.c
@@ -0,0 +1,35 @@
+#include <kernel/clock.h>
+#include "priv_gpio.h"
+#include <kernel/task.h>
+
+void task1(void);
+void task2(void);
+
+
+
+void user_main(void)
+{
+	gpio(GPIO_MODE, 5, OUTPUT);
+	task_start(task1, 512);
+
+	for (int i = 0; i < 8; i++) {
+		gpio(GPIO_OUT, 5, !(i & 1));
+		delay(200);
+	}
+}
+
+void task1(void)
+{
+	delay(400);
+	task_start(task2, 1024);
+}
+
+void task2(void)
+{
+	int state = 0;
+	delay(2500);
+	while (1) {
+		gpio(GPIO_OUT, 5, state ^= 1);
+		delay(500);
+	}
+}