Add support for M16C timer interrupt

git-svn-id: svn://svn.code.sf.net/p/nuttx/code/trunk@1505 42af7a65-404d-4744-a932-0658087f49c3

1 files changed, 183 insertions, 0 deletions

diff --git a/nuttx/arch/sh/src/m16c/m16c_timerisr.c b/nuttx/arch/sh/src/m16c/m16c_timerisr.c
new file mode 100644
index 000000000..962166071
--- /dev/null
+++ b/nuttx/arch/sh/src/m16c/m16c_timerisr.c
@@ -0,0 +1,183 @@
+/****************************************************************************
+ * arch/sh/src/m16c/m16c_timerisr.c
+ *
+ *   Copyright (C) 2009 Gregory Nutt. All rights reserved.
+ *   Author: Gregory Nutt <spudmonkey@racsa.co.cr>
+ *
+ * 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. Neither the name NuttX nor the names of its contributors may be
+ *    used to endorse or promote products derived from this software
+ *    without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+ * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
+ * COPYRIGHT OWNER OR CONTRIBUTORS 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.
+ *
+ ****************************************************************************/
+
+/****************************************************************************
+ * Included Files
+ ****************************************************************************/
+
+#include <nuttx/config.h>
+#include <sys/types.h>
+#include <time.h>
+#include <debug.h>
+#include <nuttx/arch.h>
+
+#include "clock_internal.h"
+#include "up_internal.h"
+#include "up_arch.h"
+
+#include "chip.h"
+#include "m16c_timer.h"
+
+/****************************************************************************
+ * Preprocessor Definitions
+ ****************************************************************************/
+/* Configuration */
+
+#ifndef M16C_TA0_PRIO              /* Timer A0 interrupt priority */
+#  define M16C_TA0_PRIO   5
+#endif
+
+/* Determine the ideal preload value for the timer.
+ *
+ * For example, given a 20MHz input frequency and a desired 100 Hz, clock,
+ * the ideal reload value would be:
+ *
+ *  20,000,000 / 100 = 200,000
+ *
+ * The ideal prescaler value would be the one, then that drops this to exactly
+ * 66535:
+ *
+ *  M16C_IDEAL_PRESCALER = 200,000 / 65535 = 3.05
+ *
+ * And any value greater than 3.05 would also work with less and less precision.
+ * The following calculation will produce the ideal prescaler as the next integer
+ * value above any fractional values:
+ */
+
+#define M16C_DIVISOR (65535 * CLK_TCK)
+#define M16C_IDEAL_PRESCALER \
+	((M16C_XIN_FREQ + M16C_DIVISOR - 1) / M16C_DIVISOR)
+
+/* Now, given this idel prescaler value, pick between available choices: 1, 8, and 32 */
+
+#if M16C_IDEAL_PRESCALER > 8
+#  define M16C_PRESCALE_VALUE 32
+#  define M16C_PRESCALE_BITS TAnMR_TCK_TMF32
+#elif M16C_IDEL_PRESCALER > 1
+#  define M16C_PRESCALE_VALUE 8
+#  define M16C_PRESCALE_BITS TAnMR_TCK_TMF8
+#else
+#  define M16C_PRESCALE_VALUE 1
+#  define M16C_PRESCALE_BITS TAnMR_TCK_TMF1
+#endif
+
+/* Timer 0 Mode Settings */
+
+#define M16C_TA0MODE_CONFIG \
+	(TAnMR_TMOD_TIMER|TAnMR_MR_TMNOOUT|TAnMR_MR_TMNOGATE|M16C_PRESCALE_BITS)
+
+/* The actual reload value matching the selected prescaler value */
+
+#define M16C_RELOAD_VALUE \
+	((M16C_XIN_FREQ / M16C_PRESCALE_VALUE / CLK_TCK)  - 1)
+
+/****************************************************************************
+ * Private Type Definitions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Private Function Prototypes
+ ****************************************************************************/
+
+/****************************************************************************
+ * Global Functions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Function:  up_timerisr
+ *
+ * Description:
+ *   The timer ISR will perform a variety of services for various portions
+ *   of the systems.
+ *
+ ****************************************************************************/
+
+int up_timerisr(int irq, uint32 *regs)
+{
+   /* Process timer interrupt */
+
+   sched_process_timer();
+   return 0;
+}
+
+/****************************************************************************
+ * Function:  up_timerinit
+ *
+ * Description:
+ *   This function is called during start-up to initialize
+ *   the timer interrupt.
+ *
+ ****************************************************************************/
+
+void up_timerinit(void)
+{
+  /* Make sure that no timers are running and that all timer interrupts are
+   * disabled.
+   */
+
+  putreg8(0, M16C_TABSR);
+  putreg8(0, M16C_TA0IC);
+  putreg8(0, M16C_TA1IC);
+  putreg8(0, M16C_TA2IC);
+  putreg8(0, M16C_TA3IC);
+  putreg8(0, M16C_TA4IC);
+  putreg8(0, M16C_TB0IC);
+  putreg8(0, M16C_TB1IC);
+  putreg8(0, M16C_TB2IC);
+
+  /* Set up timer 0 mode register for timer mode with the calculated prescaler value */
+ 
+  putreg8(M16C_TA0MODE_CONFIG, M16C_TA0MR);
+
+  /* Set the calculated reload value */
+
+  putreg16(M16C_RELOAD_VALUE, M16C_TA0);
+ 
+  /* Attach the interrupt handler */
+
+  irq_attach(M16C_SYSTIMER_IRQ, (xcpt_t)up_timerisr);
+
+  /* Enable timer interrupts */
+
+  putreg8(1, M16C_TA0IC);
+  
+  /* Set the interrupt priority */
+
+  putreg8(M16C_TA0_PRIO, M16C_TA0IC);
+
+  /* Start the timer */
+
+  putreg8(TABSR_TA0S, M16C_TABSR);
+}