source: rtems/c/src/lib/libcpu/powerpc/ppc403/clock/clock.c @ 879a047

4.104.114.84.95
Last change on this file since 879a047 was 879a047, checked in by Joel Sherrill <joel.sherrill@…>, on Sep 26, 1995 at 1:25:58 PM

fixed Id strings

  • Property mode set to 100644
File size: 6.5 KB
Line 
1/*  clock.c
2 *
3 *  This routine initializes the interval timer on the
4 *  PowerPC 403 CPU.  The tick frequency is specified by the bsp.
5 *
6 *  Author:     Andrew Bray <andy@i-cubed.demon.co.uk>
7 *
8 *  COPYRIGHT (c) 1995 by i-cubed ltd.
9 *
10 *  To anyone who acknowledges that this file is provided "AS IS"
11 *  without any express or implied warranty:
12 *      permission to use, copy, modify, and distribute this file
13 *      for any purpose is hereby granted without fee, provided that
14 *      the above copyright notice and this notice appears in all
15 *      copies, and that the name of i-cubed limited not be used in
16 *      advertising or publicity pertaining to distribution of the
17 *      software without specific, written prior permission.
18 *      i-cubed limited makes no representations about the suitability
19 *      of this software for any purpose.
20 *
21 *  Derived from c/src/lib/libcpu/hppa1_1/clock/clock.c:
22 *
23 *  COPYRIGHT (c) 1989, 1990, 1991, 1992, 1993, 1994.
24 *  On-Line Applications Research Corporation (OAR).
25 *  All rights assigned to U.S. Government, 1994.
26 *
27 *  This material may be reproduced by or for the U.S. Government pursuant
28 *  to the copyright license under the clause at DFARS 252.227-7013.  This
29 *  notice must appear in all copies of this file and its derivatives.
30 *
31 *  $Id$
32 */
33
34#include <bsp.h>
35#include <clockdrv.h>
36#include <rtems/libio.h>
37
38#include <stdlib.h>                     /* for atexit() */
39
40extern rtems_cpu_table           Cpu_table;             /* owned by BSP */
41
42volatile rtems_unsigned32 Clock_driver_ticks;
43static rtems_unsigned32 pit_value, tick_time;
44static rtems_boolean auto_restart;
45
46void Clock_exit( void );
47 
48/*
49 * These are set by clock driver during its init
50 */
51 
52rtems_device_major_number rtems_clock_major = ~0;
53rtems_device_minor_number rtems_clock_minor;
54 
55static INLINE rtems_unsigned32 get_itimer(void)
56{
57    register rtems_unsigned32 rc;
58
59    asm volatile ("mftblo %0" : "=r" ((rc)));
60
61    return rc;
62}
63
64/*
65 *  ISR Handler
66 */
67 
68rtems_isr
69Clock_isr(rtems_vector_number vector)
70{
71    if (!auto_restart)
72        {
73            rtems_unsigned32 clicks_til_next_interrupt;
74            rtems_unsigned32 itimer_value;
75
76            /*
77             * setup for next interrupt; making sure the new value is reasonably
78             * in the future.... in case we lost out on an interrupt somehow
79             */
80
81            itimer_value = get_itimer();
82            tick_time += pit_value;
83
84            /*
85             * how far away is next interrupt *really*
86             * It may be a long time; this subtraction works even if
87             * Clock_clicks_interrupt < Clock_clicks_low_order via
88             * the miracle of unsigned math.
89             */
90            clicks_til_next_interrupt = tick_time - itimer_value;
91
92            /*
93             * If it is too soon then bump it up.
94             * This should only happen if CPU_HPPA_CLICKS_PER_TICK is too small.
95             * But setting it low is useful for debug, so...
96             */
97
98            if (clicks_til_next_interrupt < 400)
99                {
100                    tick_time = itimer_value + 1000;
101                    clicks_til_next_interrupt = 1000;
102                    /* XXX: count these! this should be rare */
103                }
104
105            /*
106             * If it is too late, that means we missed the interrupt somehow.
107             * Rather than wait 35-50s for a wrap, we just fudge it here.
108             */
109           
110            if (clicks_til_next_interrupt > pit_value)
111                {
112                    tick_time = itimer_value + 1000;
113                    clicks_til_next_interrupt = 1000;
114                    /* XXX: count these! this should never happen :-) */
115                }
116
117            asm volatile ("mtpit %0" :: "r" (clicks_til_next_interrupt));
118        }
119
120    asm volatile ( "mttsr %0" :: "r" (0x08000000));
121
122    Clock_driver_ticks++;
123
124    rtems_clock_tick();
125}
126
127void Install_clock(rtems_isr_entry clock_isr)
128{
129    rtems_isr_entry previous_isr;
130    rtems_unsigned32 pvr, iocr;
131
132    Clock_driver_ticks = 0;
133
134    asm volatile ("mfiocr %0" : "=r" (iocr));
135    iocr &= ~4;
136    iocr |= 4;  /* Select external timer clock */
137    asm volatile ("mtiocr %0" : "=r" (iocr) : "0" (iocr));
138
139    asm volatile ("mfpvr %0" : "=r" ((pvr)));
140
141    if (((pvr & 0xffff0000) >> 16) != 0x0020)
142        return; /* Not a ppc403 */
143
144    if ((pvr & 0xff00) == 0x0000) /* 403GA */
145        auto_restart = (pvr & 0x00f0) > 0x0000 ? 1 : 0;
146    else if ((pvr & 0xff00) == 0x0100) /* 403GB */
147        auto_restart = 1;
148
149    pit_value = BSP_Configuration.microseconds_per_tick *
150        Cpu_table.clicks_per_usec;
151
152    if (BSP_Configuration.ticks_per_timeslice)
153    {
154        register rtems_unsigned32 tcr;
155        /*
156         * initialize the interval here
157         * First tick is set to right amount of time in the future
158         * Future ticks will be incremented over last value set
159         * in order to provide consistent clicks in the face of
160         * interrupt overhead
161         */
162
163        rtems_interrupt_catch(clock_isr, PPC_IRQ_PIT,
164                              &previous_isr);
165
166        asm volatile ("mtpit %0" : : "r" (pit_value));
167
168        asm volatile ("mftcr %0" : "=r" ((tcr)));
169
170        tcr &= ~ 0x04400000;
171
172        tcr |= (auto_restart ? 0x04400000 : 0x04000000);
173
174        tick_time = get_itimer() + pit_value;
175
176        asm volatile ("mttcr %0" : "=r" ((tcr)) : "0" ((tcr)));
177    }
178    atexit(Clock_exit);
179}
180
181void
182ReInstall_clock(rtems_isr_entry new_clock_isr)
183{
184    rtems_isr_entry previous_isr;
185    rtems_unsigned32 isrlevel = 0;
186
187    rtems_interrupt_disable(isrlevel);
188   
189    rtems_interrupt_catch(new_clock_isr, PPC_IRQ_PIT,
190                          &previous_isr);
191
192    rtems_interrupt_enable(isrlevel);
193}
194
195
196/*
197 * Called via atexit()
198 * Remove the clock interrupt handler by setting handler to NULL
199 */
200
201void
202Clock_exit(void)
203{
204    if ( BSP_Configuration.ticks_per_timeslice )
205    {
206        register rtems_unsigned32 tcr;
207
208        asm volatile ("mftcr %0" : "=r" ((tcr)));
209
210        tcr &= ~ 0x04400000;
211
212        asm volatile ("mttcr %0" : "=r" ((tcr)) : "0" ((tcr)));
213
214        (void) set_vector(0, PPC_IRQ_PIT, 1);
215    }
216}
217
218rtems_device_driver Clock_initialize(
219  rtems_device_major_number major,
220  rtems_device_minor_number minor,
221  void *pargp
222)
223{
224  Install_clock( Clock_isr );
225 
226  /*
227   * make major/minor avail to others such as shared memory driver
228   */
229 
230  rtems_clock_major = major;
231  rtems_clock_minor = minor;
232 
233  return RTEMS_SUCCESSFUL;
234}
235 
236rtems_device_driver Clock_control(
237  rtems_device_major_number major,
238  rtems_device_minor_number minor,
239  void *pargp
240)
241{
242    rtems_libio_ioctl_args_t *args = pargp;
243 
244    if (args == 0)
245        goto done;
246 
247    /*
248     * This is hokey, but until we get a defined interface
249     * to do this, it will just be this simple...
250     */
251 
252    if (args->command == rtems_build_name('I', 'S', 'R', ' '))
253    {
254        Clock_isr(PPC_IRQ_PIT);
255    }
256    else if (args->command == rtems_build_name('N', 'E', 'W', ' '))
257    {
258        ReInstall_clock(args->buffer);
259    }
260 
261done:
262    return RTEMS_SUCCESSFUL;
263}
264
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