Gigabeat S: Get timer API working. metronome will work now.

git-svn-id: svn://svn.rockbox.org/rockbox/trunk@19676 a1c6a512-1295-4272-9138-f99709370657

firmware/target/arm/imx31/gigabeat-s/timer-imx31.c

@@ -0,0 +1,112 @@
+/***************************************************************************
+*             __________               __   ___.
+*   Open      \______   \ ____   ____ |  | _\_ |__   _______  ___
+*   Source     |       _//  _ \_/ ___\|  |/ /| __ \ /  _ \  \/  /
+*   Jukebox    |    |   (  <_> )  \___|    < | \_\ (  <_> > <  <
+*   Firmware   |____|_  /\____/ \___  >__|_ \|___  /\____/__/\_ \
+*                     \/            \/     \/    \/            \/
+* $Id$
+*
+* Copyright (C) 2007 by Michael Sevakis
+*
+* 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 2
+* of the License, or (at your option) any later version.
+*
+* This software is distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY
+* KIND, either express or implied.
+*
+****************************************************************************/
+#include "config.h"
+#include "system.h"
+#include "timer.h"
+#include "clkctl-imx31.h"
+#include "avic-imx31.h"
+
+static void __attribute__((interrupt("IRQ"))) EPIT2_HANDLER(void)
+{
+    EPITSR2 = EPITSR_OCIF; /* Clear the pending status */
+
+    if (pfn_timer != NULL)
+        pfn_timer();
+}
+
+static void stop_timer(bool clock_off)
+{
+    /* Ensure clock gating on (before touching any module registers) */
+    imx31_clkctl_module_clock_gating(CG_EPIT2, CGM_ON_ALL);
+    /* Disable insterrupt */
+    avic_disable_int(EPIT2);
+    /* Clear wakeup mask */
+    CLKCTL_WIMR0 &= ~WIM_IPI_INT_EPIT2;
+    /* Disable counter */
+    EPITCR2 &= ~(EPITCR_OCIEN | EPITCR_EN);
+    /* Clear pending */
+    EPITSR2 = EPITSR_OCIF;
+
+    if (clock_off)
+    {
+        /* Final stop, not reset; don't clock module any longer */
+        imx31_clkctl_module_clock_gating(CG_EPIT2, CGM_OFF);
+    }
+}
+
+bool _timer_set(long cycles, bool start)
+{
+    /* Maximum cycle count expressible in the cycles parameter is 2^31-1
+     * and the modulus counter is capable of 2^32-1 and as a result there is
+     * no requirement to use a prescaler > 1. This gives a frequency range of
+     * ~0.015366822Hz - 66000000Hz. The highest input frequency gives the
+     * greatest possible accuracy anyway. */ 
+    int oldstatus = disable_interrupt_save(IRQ_FIQ_STATUS);
+
+    /* Halt timer if running - leave module clock enabled */
+    stop_timer(false);
+
+    if (start && pfn_unregister != NULL)
+    {
+        pfn_unregister();
+        pfn_unregister = NULL;
+    }
+
+    /* CLKSRC = ipg_clk,
+     * EPIT output disconnected,
+     * Enabled in wait mode
+     * Prescale 1 for 66MHz
+     * Reload from modulus register,
+     * Count from load value */
+    EPITCR2 = EPITCR_CLKSRC_IPG_CLK | EPITCR_WAITEN | EPITCR_IOVW |
+              EPITCR_PRESCALER(1-1) | EPITCR_RLD | EPITCR_ENMOD;
+    EPITLR2 = cycles;
+    /* Event when counter reaches 0 */
+    EPITCMPR2 = 0;
+
+    restore_interrupt(oldstatus);
+    return true;
+}
+
+bool _timer_register(void)
+{
+    int oldstatus = disable_interrupt_save(IRQ_FIQ_STATUS);
+
+    /* Halt timer if running - leave module clock enabled */
+    stop_timer(false);
+
+    /* Enable interrupt */
+    EPITCR2 |= EPITCR_OCIEN;
+    avic_enable_int(EPIT2, IRQ, 8, EPIT2_HANDLER);
+    /* Start timer */
+    EPITCR2 |= EPITCR_EN;
+
+    restore_interrupt(oldstatus);
+    return true;
+}
+
+void _timer_unregister(void)
+{
+    int oldstatus = disable_interrupt_save(IRQ_FIQ_STATUS);
+    /* Halt timer if running - stop module clock */
+    stop_timer(true);
+    restore_interrupt(oldstatus);
+}

firmware/target/arm/imx31/gigabeat-s/timer-target.h

@@ -0,0 +1,41 @@
+/***************************************************************************
+*             __________               __   ___.
+*   Open      \______   \ ____   ____ |  | _\_ |__   _______  ___
+*   Source     |       _//  _ \_/ ___\|  |/ /| __ \ /  _ \  \/  /
+*   Jukebox    |    |   (  <_> )  \___|    < | \_\ (  <_> > <  <
+*   Firmware   |____|_  /\____/ \___  >__|_ \|___  /\____/__/\_ \
+*                     \/            \/     \/    \/            \/
+* $Id$
+*
+* Copyright (C) 2007 by Michael Sevakis
+*
+* 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 2
+* of the License, or (at your option) any later version.
+*
+* This software is distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY
+* KIND, either express or implied.
+*
+****************************************************************************/
+#ifndef TIMER_TARGET_H
+#define TIMER_TARGET_H
+
+/* timer is based on ipg_clk */
+#define TIMER_FREQ (66000000)
+
+bool _timer_set(long cycles, bool set);
+bool _timer_register(void);
+void _timer_unregister(void);
+
+#define __TIMER_SET(cycles, set) \
+    _timer_set(cycles, set)
+
+#define __TIMER_REGISTER(reg_prio, unregister_callback, cycles, \
+                              int_prio, timer_callback) \
+    _timer_register()
+
+#define __TIMER_UNREGISTER(...) \
+    _timer_unregister()
+
+#endif /* TIMER_TARGET_H */