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authorDavid A. Mellis <d.mellis@arduino.cc>2012-09-13 10:41:16 -0400
committerDavid A. Mellis <d.mellis@arduino.cc>2012-09-13 10:41:16 -0400
commit0d9a111face4f3629bcae8e52af843792af3b453 (patch)
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+/* This source file is part of the ATMEL AVR-UC3-SoftwareFramework-1.7.0 Release */
+
+/*This file is prepared for Doxygen automatic documentation generation.*/
+/*! \file *********************************************************************
+ *
+ * \brief INTC driver for AVR32 UC3.
+ *
+ * AVR32 Interrupt Controller driver module.
+ *
+ * - Compiler: IAR EWAVR32 and GNU GCC for AVR32
+ * - Supported devices: All AVR32 devices with an INTC module can be used.
+ * - AppNote:
+ *
+ * \author Atmel Corporation: http://www.atmel.com \n
+ * Support and FAQ: http://support.atmel.no/
+ *
+ ******************************************************************************/
+
+/* Copyright (c) 2009 Atmel Corporation. All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright notice, this
+ * list of conditions and the following disclaimer.
+ *
+ * 2. Redistributions in binary form must reproduce the above copyright notice,
+ * this list of conditions and the following disclaimer in the documentation
+ * and/or other materials provided with the distribution.
+ *
+ * 3. The name of Atmel may not be used to endorse or promote products derived
+ * from this software without specific prior written permission.
+ *
+ * 4. This software may only be redistributed and used in connection with an Atmel
+ * AVR product.
+ *
+ * THIS SOFTWARE IS PROVIDED BY ATMEL "AS IS" AND ANY EXPRESS OR IMPLIED
+ * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
+ * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NON-INFRINGEMENT ARE
+ * EXPRESSLY AND SPECIFICALLY DISCLAIMED. IN NO EVENT SHALL ATMEL BE LIABLE FOR
+ * ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
+ * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
+ * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
+ * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
+ * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE
+ *
+ */
+
+#include <avr32/io.h>
+#include "compiler.h"
+#include "preprocessor.h"
+#include "intc.h"
+
+// define _evba from exception.S
+extern void _evba;
+
+//! Values to store in the interrupt priority registers for the various interrupt priority levels.
+extern const unsigned int ipr_val[AVR32_INTC_NUM_INT_LEVELS];
+
+//! Creates a table of interrupt line handlers per interrupt group in order to optimize RAM space.
+//! Each line handler table contains a set of pointers to interrupt handlers.
+#if (defined __GNUC__)
+#define DECL_INT_LINE_HANDLER_TABLE(GRP, unused) \
+static volatile __int_handler _int_line_handler_table_##GRP[Max(AVR32_INTC_NUM_IRQS_PER_GRP##GRP, 1)];
+#elif (defined __ICCAVR32__)
+#define DECL_INT_LINE_HANDLER_TABLE(GRP, unused) \
+static volatile __no_init __int_handler _int_line_handler_table_##GRP[Max(AVR32_INTC_NUM_IRQS_PER_GRP##GRP, 1)];
+#endif
+MREPEAT(AVR32_INTC_NUM_INT_GRPS, DECL_INT_LINE_HANDLER_TABLE, ~);
+#undef DECL_INT_LINE_HANDLER_TABLE
+
+//! Table containing for each interrupt group the number of interrupt request
+//! lines and a pointer to the table of interrupt line handlers.
+static const struct
+{
+ unsigned int num_irqs;
+ volatile __int_handler *_int_line_handler_table;
+} _int_handler_table[AVR32_INTC_NUM_INT_GRPS] =
+{
+#define INSERT_INT_LINE_HANDLER_TABLE(GRP, unused) \
+ {AVR32_INTC_NUM_IRQS_PER_GRP##GRP, _int_line_handler_table_##GRP},
+ MREPEAT(AVR32_INTC_NUM_INT_GRPS, INSERT_INT_LINE_HANDLER_TABLE, ~)
+#undef INSERT_INT_LINE_HANDLER_TABLE
+};
+
+
+/*! \brief Default interrupt handler.
+ *
+ * \note Taken and adapted from Newlib.
+ */
+#if (defined __GNUC__)
+__attribute__((__interrupt__))
+#elif (defined __ICCAVR32__)
+__interrupt
+#endif
+static void _unhandled_interrupt(void)
+{
+ // Catch unregistered interrupts.
+ while (TRUE);
+}
+
+
+/*! \brief Gets the interrupt handler of the current event at the \a int_level
+ * interrupt priority level (called from exception.S).
+ *
+ * \param int_level Interrupt priority level to handle.
+ *
+ * \return Interrupt handler to execute.
+ *
+ * \note Taken and adapted from Newlib.
+ */
+__int_handler _get_interrupt_handler(unsigned int int_level)
+{
+ // ICR3 is mapped first, ICR0 last.
+ // Code in exception.S puts int_level in R12 which is used by AVR32-GCC to
+ // pass a single argument to a function.
+ unsigned int int_grp = AVR32_INTC.icr[AVR32_INTC_INT3 - int_level];
+ unsigned int int_req = AVR32_INTC.irr[int_grp];
+
+ // As an interrupt may disappear while it is being fetched by the CPU
+ // (spurious interrupt caused by a delayed response from an MCU peripheral to
+ // an interrupt flag clear or interrupt disable instruction), check if there
+ // are remaining interrupt lines to process.
+ // If a spurious interrupt occurs, the status register (SR) contains an
+ // execution mode and interrupt level masks corresponding to a level 0
+ // interrupt, whatever the interrupt priority level causing the spurious
+ // event. This behavior has been chosen because a spurious interrupt has not
+ // to be a priority one and because it may not cause any trouble to other
+ // interrupts.
+ // However, these spurious interrupts place the hardware in an unstable state
+ // and could give problems in other/future versions of the CPU, so the
+ // software has to be written so that they never occur. The only safe way of
+ // achieving this is to always clear or disable peripheral interrupts with the
+ // following sequence:
+ // 1: Mask the interrupt in the CPU by setting GM (or IxM) in SR.
+ // 2: Perform the bus access to the peripheral register that clears or
+ // disables the interrupt.
+ // 3: Wait until the interrupt has actually been cleared or disabled by the
+ // peripheral. This is usually performed by reading from a register in the
+ // same peripheral (it DOES NOT have to be the same register that was
+ // accessed in step 2, but it MUST be in the same peripheral), what takes
+ // bus system latencies into account, but peripheral internal latencies
+ // (generally 0 cycle) also have to be considered.
+ // 4: Unmask the interrupt in the CPU by clearing GM (or IxM) in SR.
+ // Note that steps 1 and 4 are useless inside interrupt handlers as the
+ // corresponding interrupt level is automatically masked by IxM (unless IxM is
+ // explicitly cleared by the software).
+ //
+ // Get the right IRQ handler.
+ //
+ // If several interrupt lines are active in the group, the interrupt line with
+ // the highest number is selected. This is to be coherent with the
+ // prioritization of interrupt groups performed by the hardware interrupt
+ // controller.
+ //
+ // If no handler has been registered for the pending interrupt,
+ // _unhandled_interrupt will be selected thanks to the initialization of
+ // _int_line_handler_table_x by INTC_init_interrupts.
+ //
+ // exception.S will provide the interrupt handler with a clean interrupt stack
+ // frame, with nothing more pushed onto the stack. The interrupt handler must
+ // manage the `rete' instruction, what can be done thanks to pure assembly,
+ // inline assembly or the `__attribute__((__interrupt__))' C function
+ // attribute.
+ return (int_req) ? _int_handler_table[int_grp]._int_line_handler_table[32 - clz(int_req) - 1] : NULL;
+}
+
+//! Init EVBA address. This sequence might also be done in the UTILS/STARTUP/GCC/crt0.S
+static __inline__ void INTC_init_evba(void)
+{
+ Set_system_register(AVR32_EVBA, (int)&_evba );
+}
+
+void INTC_init_interrupts(void)
+{
+ unsigned int int_grp, int_req;
+
+ INTC_init_evba();
+
+ // For all interrupt groups,
+ for (int_grp = 0; int_grp < AVR32_INTC_NUM_INT_GRPS; int_grp++)
+ {
+ // For all interrupt request lines of each group,
+ for (int_req = 0; int_req < _int_handler_table[int_grp].num_irqs; int_req++)
+ {
+ // Assign _unhandled_interrupt as default interrupt handler.
+ _int_handler_table[int_grp]._int_line_handler_table[int_req] = &_unhandled_interrupt;
+ }
+
+ // Set the interrupt group priority register to its default value.
+ // By default, all interrupt groups are linked to the interrupt priority
+ // level 0 and to the interrupt vector _int0.
+ AVR32_INTC.ipr[int_grp] = ipr_val[AVR32_INTC_INT0];
+ }
+}
+
+
+void INTC_register_interrupt(__int_handler handler, unsigned int irq, unsigned int int_level)
+{
+ // Determine the group of the IRQ.
+ unsigned int int_grp = irq / AVR32_INTC_MAX_NUM_IRQS_PER_GRP;
+
+ // Store in _int_line_handler_table_x the pointer to the interrupt handler, so
+ // that _get_interrupt_handler can retrieve it when the interrupt is vectored.
+ _int_handler_table[int_grp]._int_line_handler_table[irq % AVR32_INTC_MAX_NUM_IRQS_PER_GRP] = handler;
+
+ // Program the corresponding IPRX register to set the interrupt priority level
+ // and the interrupt vector offset that will be fetched by the core interrupt
+ // system.
+ // NOTE: The _intx functions are intermediate assembly functions between the
+ // core interrupt system and the user interrupt handler.
+ AVR32_INTC.ipr[int_grp] = ipr_val[int_level & (AVR32_INTC_IPR_INTLEVEL_MASK >> AVR32_INTC_IPR_INTLEVEL_OFFSET)];
+}