Moved implementation of user timer to the firmware layer, implemented it for iriver, and made it shareable based on priorities. On iriver, the user timer is shared between the backlight fading and other use, so if a plugin registers the timer, the backlight will resort to simple on/off switching until the plugin releases the timer again. Sorted and bumped the plugin api.

git-svn-id: svn://svn.rockbox.org/rockbox/trunk@7242 a1c6a512-1295-4272-9138-f99709370657

firmware/timer.c

@@ -0,0 +1,181 @@
+/***************************************************************************
+*             __________               __   ___.
+*   Open      \______   \ ____   ____ |  | _\_ |__   _______  ___
+*   Source     |       _//  _ \_/ ___\|  |/ /| __ \ /  _ \  \/  /
+*   Jukebox    |    |   (  <_> )  \___|    < | \_\ (  <_> > <  <
+*   Firmware   |____|_  /\____/ \___  >__|_ \|___  /\____/__/\_ \
+*                     \/            \/     \/    \/            \/
+* $Id$
+*
+* Copyright (C) 2005 Jens Arnold
+*
+* All files in this archive are subject to the GNU General Public License.
+* See the file COPYING in the source tree root for full license agreement.
+*
+* This software is distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY
+* KIND, either express or implied.
+*
+****************************************************************************/
+
+#include <stdbool.h>
+#include "config.h"
+#include "cpu.h"
+#include "system.h"
+#include "timer.h"
+
+#ifndef SIMULATOR
+
+static int timer_prio = -1;
+static void (*pfn_timer)(void) = NULL;      /* timer callback */
+static void (*pfn_unregister)(void) = NULL; /* unregister callback */
+
+
+/* interrupt handler */
+#if CONFIG_CPU == SH7034
+void IMIA4(void) __attribute__((interrupt_handler));
+void IMIA4(void)
+{
+    if (pfn_timer != NULL)
+        pfn_timer();
+    and_b(~0x01, &TSR4); /* clear the interrupt */
+}
+#elif defined CPU_COLDFIRE
+void TIMER1(void) __attribute__ ((interrupt_handler));
+void TIMER1(void)
+{
+    if (pfn_timer != NULL)
+        pfn_timer();
+    TER1 = 0xff; /* clear all events */
+}
+#endif /* CONFIG_CPU */
+
+static bool timer_set(long cycles, bool start)
+{
+    int phi = 0; /* bits for the prescaler */
+    int prescale = 1;
+    
+#ifdef CPU_COLDFIRE
+    cycles >>= 1; /* the coldfire timer works on busclk == cpuclk/2 */
+#endif
+
+    while (cycles > 0x10000)
+    {   /* work out the smallest prescaler that makes it fit */
+#if CONFIG_CPU == SH7034
+        phi++;
+#endif
+        prescale *= 2;
+        cycles >>= 1;
+    }
+
+#if CONFIG_CPU == SH7034
+    if (prescale > 8)
+        return false;
+
+    if (start)
+    {
+        if (pfn_unregister != NULL)
+        {
+            pfn_unregister();
+            pfn_unregister = NULL;
+        }
+
+        and_b(~0x10, &TSTR); /* Stop the timer 4 */
+        and_b(~0x10, &TSNC); /* No synchronization */
+        and_b(~0x10, &TMDR); /* Operate normally */
+
+        TIER4 = 0xF9;        /* Enable GRA match interrupt */
+    }
+
+    TCR4 = 0x20 | phi;   /* clear at GRA match, set prescaler */
+    GRA4 = (unsigned short)(cycles - 1);
+    if (start || (TCNT4 >= GRA4))
+        TCNT4 = 0;
+    and_b(~0x01, &TSR4); /* clear an eventual interrupt */
+
+#elif defined CPU_COLDFIRE
+    if (prescale > 4096)
+        return false;
+
+    if (prescale > 256)
+    {
+        phi = 0x05;      /* prescale sysclk/16, timer enabled */
+        prescale >>= 4;
+    }
+    else
+        phi = 0x03;      /* prescale sysclk, timer enabled */
+
+    if (start)
+    {
+        if (pfn_unregister != NULL)
+        {
+            pfn_unregister();
+            pfn_unregister = NULL;
+        }
+        phi &= ~1;       /* timer disabled at start */
+    }
+
+    /* We are using timer 1 */
+    TMR1 = 0x0018 | (unsigned short)phi | ((unsigned short)(prescale - 1) << 8);
+    TRR1 = (unsigned short)(cycles - 1);
+    if (start || (TCN1 >= TRR1))
+        TCN1 = 0; /* reset the timer */
+    TER1 = 0xff;  /* clear all events */
+
+#endif /* CONFIG_CPU */
+    return true;
+}
+
+/* Register a user timer, called every <count> CPU cycles */
+bool timer_register(int reg_prio, void (*unregister_callback)(void),
+                    long cycles, int int_prio, void (*timer_callback)(void))
+{
+    if (reg_prio <= timer_prio || cycles == 0)
+        return false;
+
+#if CONFIG_CPU == SH7034
+    if (int_prio < 1 || int_prio > 15)
+        return false;
+#elif defined CPU_COLDFIRE
+    (void)int_prio;
+#endif
+
+    if (!timer_set(cycles, true))
+        return false;
+        
+    pfn_timer = timer_callback;
+    pfn_unregister = unregister_callback;
+    timer_prio = reg_prio;
+
+#if CONFIG_CPU == SH7034
+    IPRD = (IPRD & 0xFF0F) | int_prio << 4;  /* interrupt priority */
+    or_b(0x10, &TSTR); /* start timer 4 */
+#elif defined CPU_COLDFIRE
+    /* ICR2 (Timer1) */
+    ICR0 = (ICR0 & 0xffff00ff) | 0x00009000; /* interrupt on level 4.0 */
+    and_l(~(1<<10), &IMR);
+    TMR1 |= 1;         /* start timer */
+#endif
+
+    return true;
+}
+
+bool timer_set_period(long cycles)
+{
+    return timer_set(cycles, false);
+}
+
+void timer_unregister(void)
+{
+#if CONFIG_CPU == SH7034
+    and_b(~0x10, &TSTR);    /* stop the timer 4 */
+    IPRD = (IPRD & 0xFF0F); /* disable interrupt */
+#elif defined CPU_COLDFIRE
+    TMR1 = 0;               /* disable timer 1 */
+    or_l((1<<10), &IMR);    /* disable interrupt */
+#endif
+    pfn_timer = NULL;
+    pfn_unregister = NULL;
+    timer_prio = -1;
+}
+
+#endif /* !SIMULATOR */