summaryrefslogtreecommitdiffstats
path: root/firmware/timer.c
blob: d4ce0696378c54c1097cfe08f2d0d84f4de13063 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
/***************************************************************************
*             __________               __   ___.
*   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 */
#ifdef CPU_COLDFIRE
static int base_prescale;
#endif

/* 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;

#if (CONFIG_CPU==PP5020) || (CONFIG_CPU==PNX0101)
    /* TODO: Implement for iPod and iFP */
    (void)start;
    (void)phi;
#endif

#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/CPUFREQ_MAX_MULT)
        return false;

    if (prescale > 256/CPUFREQ_MAX_MULT)
    {
        phi = 0x05;      /* prescale sysclk/16, timer enabled */
        prescale >>= 4;
    }
    else
        phi = 0x03;      /* prescale sysclk, timer enabled */
        
    base_prescale = prescale;
    prescale *= (cpu_frequency / CPU_FREQ);

    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;
}

#ifdef CPU_COLDFIRE
void timers_adjust_prescale(int multiplier, bool enable_irq)
{
    /* tick timer */
    TMR0 = (TMR0 & 0x00ef)
         | ((unsigned short)(multiplier - 1) << 8)
         | (enable_irq ? 0x10 : 0);

    if (pfn_timer)
    {
        /* user timer */
        int prescale = base_prescale * multiplier;
        TMR1 = (TMR1 & 0x00ef)
             | ((unsigned short)(prescale - 1) << 8)
             | (enable_irq ? 0x10 : 0);
    }
}
#endif

/* Register a user timer, called every <cycles> CPU_FREQ 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==PP5020) || (CONFIG_CPU==PNX0101)
    /* TODO: Implement for iPod */
    (void)int_prio;
#endif

#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 = 0x90;       /* 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 */