sam3x8e: Add initial support for Arduino Due boards

This adds basic support for running on the Atmel SAM3x8e
micro-controllers that are found in the Arudino Due boards.

Signed-off-by: Kevin O'Connor <kevin@koconnor.net>

1 files changed, 115 insertions, 0 deletions

diff --git a/src/sam3x8e/gpio.c b/src/sam3x8e/gpio.c
new file mode 100644
index 00000000..78fb0f05
--- /dev/null
+++ b/src/sam3x8e/gpio.c
@@ -0,0 +1,115 @@
+// GPIO functions on sam3x8e
+//
+// Copyright (C) 2016  Kevin O'Connor <kevin@koconnor.net>
+//
+// This file may be distributed under the terms of the GNU GPLv3 license.
+
+#include <stdint.h> // uint32_t
+#include "command.h" // shutdown
+#include "compiler.h" // ARRAY_SIZE
+#include "gpio.h" // gpio_out_setup
+#include "irq.h" // irq_save
+#include "sam3x8e.h" // Pio
+#include "sched.h" // sched_shutdown
+
+
+/****************************************************************
+ * Pin mappings
+ ****************************************************************/
+
+#define GPIO(PORT, NUM) (((PORT)-'A') * 32 + (NUM))
+#define GPIO2PORT(PIN) ((PIN) / 32)
+#define GPIO2BIT(PIN) (1<<((PIN) % 32))
+
+static Pio * const digital_regs[] = {
+    PIOA, PIOB, PIOC, PIOD
+};
+
+
+/****************************************************************
+ * gpio functions
+ ****************************************************************/
+
+void
+gpio_peripheral(char bank, uint32_t bit, char ptype, uint32_t pull_up)
+{
+    Pio *regs = digital_regs[bank - 'A'];
+    if (ptype == 'A')
+        regs->PIO_ABSR &= ~bit;
+    else
+        regs->PIO_ABSR |= bit;
+    if (pull_up)
+        regs->PIO_PUER = bit;
+    else
+        regs->PIO_PUDR = bit;
+    regs->PIO_PDR = bit;
+}
+
+
+struct gpio_out
+gpio_out_setup(uint8_t pin, uint8_t val)
+{
+    if (GPIO2PORT(pin) >= ARRAY_SIZE(digital_regs))
+        goto fail;
+    Pio *regs = digital_regs[GPIO2PORT(pin)];
+    uint32_t bit = GPIO2BIT(pin);
+    irqstatus_t flag = irq_save();
+    if (val)
+        regs->PIO_SODR = bit;
+    else
+        regs->PIO_CODR = bit;
+    regs->PIO_OER = bit;
+    regs->PIO_OWER = bit;
+    regs->PIO_PER = bit;
+    irq_restore(flag);
+    return (struct gpio_out){ .regs=regs, .bit=bit };
+fail:
+    shutdown("Not an output pin");
+}
+
+void
+gpio_out_toggle(struct gpio_out g)
+{
+    Pio *regs = g.regs;
+    regs->PIO_ODSR ^= g.bit;
+}
+
+void
+gpio_out_write(struct gpio_out g, uint8_t val)
+{
+    Pio *regs = g.regs;
+    if (val)
+        regs->PIO_SODR = g.bit;
+    else
+        regs->PIO_CODR = g.bit;
+}
+
+
+struct gpio_in
+gpio_in_setup(uint8_t pin, int8_t pull_up)
+{
+    if (GPIO2PORT(pin) >= ARRAY_SIZE(digital_regs))
+        goto fail;
+    uint32_t port = GPIO2PORT(pin);
+    Pio *regs = digital_regs[port];
+    uint32_t bit = GPIO2BIT(pin);
+    irqstatus_t flag = irq_save();
+    PMC->PMC_PCER0 = 1 << (ID_PIOA + port);
+    if (pull_up)
+        regs->PIO_PUER = bit;
+    else
+        regs->PIO_PUDR = bit;
+    regs->PIO_ODR = bit;
+    regs->PIO_PER = bit;
+    irq_restore(flag);
+    return (struct gpio_in){ .regs=regs, .bit=bit };
+fail:
+    shutdown("Not an output pin");
+}
+
+uint8_t
+gpio_in_read(struct gpio_in g)
+{
+    Pio *regs = g.regs;
+    return !!(regs->PIO_PDSR & g.bit);
+}