source: rtems/c/src/lib/libcpu/hppa1.1/clock/clock.c @ 11290355

4.104.114.84.95
Last change on this file since 11290355 was 11290355, checked in by Joel Sherrill <joel.sherrill@…>, on Sep 29, 1995 at 5:19:16 PM

all targets compile .. tony's patches in place

  • Property mode set to 100644
File size: 6.5 KB
Line 
1/*  Clock
2 *
3 *  This routine initializes the interval timer on the
4 *  PA-RISC CPU.  The tick frequency is specified by the bsp.
5 *
6 *  COPYRIGHT (c) 1989, 1990, 1991, 1992, 1993, 1994.
7 *  On-Line Applications Research Corporation (OAR).
8 *  All rights assigned to U.S. Government, 1994.
9 *
10 *  This material may be reproduced by or for the U.S. Government pursuant
11 *  to the copyright license under the clause at DFARS 252.227-7013.  This
12 *  notice must appear in all copies of this file and its derivatives.
13 *
14 *  $Id$
15 */
16
17#include <rtems.h>
18#include <rtems/libio.h>
19
20/* should get this from bsp.h, but it is not installed yet */
21rtems_isr_entry set_vector(rtems_isr_entry, rtems_vector_number, int);
22extern rtems_configuration_table BSP_Configuration;
23
24#include <stdlib.h>                     /* for atexit() */
25
26extern rtems_cpu_table           Cpu_table;             /* owned by BSP */
27
28typedef unsigned long long hppa_click_count_t;
29
30/*
31 * These are set by clock driver during its init
32 */
33
34rtems_device_major_number rtems_clock_major = ~0;
35rtems_device_minor_number rtems_clock_minor;
36
37/*
38 * CPU_HPPA_CLICKS_PER_TICK is either a #define or an rtems_unsigned32
39 *   allocated and set by bsp_start()
40 */
41
42#ifndef CPU_HPPA_CLICKS_PER_TICK
43extern rtems_unsigned32 CPU_HPPA_CLICKS_PER_TICK;
44#endif
45
46volatile rtems_unsigned32 Clock_driver_ticks;
47rtems_unsigned32 Clock_isrs;              /* ISRs until next tick */
48
49rtems_unsigned32   most_recent_itimer_value;
50
51rtems_unsigned64   Clock_clicks;        /* running total of cycles */
52
53rtems_unsigned32   Clock_clicks_interrupt;
54
55void  Clock_exit(void);
56
57void
58ReInstall_clock(rtems_isr_entry new_clock_isr)
59{
60    rtems_unsigned32 isrlevel = 0;
61
62    rtems_interrupt_disable(isrlevel);
63    (void) set_vector(
64      new_clock_isr,
65      HPPA_INTERRUPT_EXTERNAL_INTERVAL_TIMER,
66      1
67    );
68    rtems_interrupt_enable(isrlevel);
69}
70
71/*
72 * read itimer and update Clock_clicks as appropriate
73 */
74
75rtems_unsigned32
76Clock_read_itimer()
77{
78    rtems_unsigned32 isrlevel;
79    rtems_unsigned32 itimer_value;
80    rtems_unsigned32 wrap_count;
81    rtems_unsigned32 recent_count;
82
83    rtems_interrupt_disable(isrlevel);
84
85    wrap_count = (Clock_clicks & 0xFFFFFFFF00000000ULL) >> 32;
86    recent_count = (rtems_unsigned32) Clock_clicks;
87
88    itimer_value = get_itimer();
89
90    if (itimer_value < recent_count)
91        wrap_count++;
92    Clock_clicks = (((rtems_unsigned64) wrap_count) << 32) + itimer_value;
93
94    rtems_interrupt_enable(isrlevel);
95
96    return itimer_value;
97}
98
99
100void Install_clock(rtems_isr_entry clock_isr)
101{
102    Clock_driver_ticks = 0;
103    Clock_clicks_interrupt = 0;
104    Clock_clicks = 0;
105
106    Clock_isrs = BSP_Configuration.microseconds_per_tick / 1000;
107
108    if (BSP_Configuration.ticks_per_timeslice)
109    {
110        /*
111         * initialize the interval here
112         * First tick is set to right amount of time in the future
113         * Future ticks will be incremented over last value set
114         * in order to provide consistent clicks in the face of
115         * interrupt overhead
116         */
117
118        Clock_clicks_interrupt = Clock_read_itimer() + CPU_HPPA_CLICKS_PER_TICK;
119        set_itimer((rtems_unsigned32) Clock_clicks_interrupt);
120
121        (void) set_vector(clock_isr, HPPA_INTERRUPT_EXTERNAL_INTERVAL_TIMER, 1);
122    }
123    atexit(Clock_exit);
124}
125
126rtems_isr
127Clock_isr(rtems_vector_number vector)
128{
129    rtems_unsigned32 clicks_til_next_interrupt;
130    rtems_unsigned32 itimer_value;
131
132    /*
133     * setup for next interrupt; making sure the new value is reasonably
134     * in the future.... in case we lost out on an interrupt somehow
135     */
136
137    itimer_value = Clock_read_itimer();
138    Clock_clicks_interrupt += CPU_HPPA_CLICKS_PER_TICK;
139
140    /*
141     * how far away is next interrupt *really*
142     * It may be a long time; this subtraction works even if
143     * Clock_clicks_interrupt < Clock_clicks_low_order via
144     * the miracle of unsigned math.
145     */
146    clicks_til_next_interrupt = Clock_clicks_interrupt - itimer_value;
147
148    /*
149     * If it is too soon then bump it up.
150     * This should only happen if CPU_HPPA_CLICKS_PER_TICK is too small.
151     * But setting it low is useful for debug, so...
152     */
153
154    if (clicks_til_next_interrupt < 400)
155    {
156        Clock_clicks_interrupt = itimer_value + 1000;
157        /* XXX: count these! this should be rare */
158    }
159
160    /*
161     * If it is too late, that means we missed the interrupt somehow.
162     * Rather than wait 35-50s for a wrap, we just fudge it here.
163     */
164
165    if (clicks_til_next_interrupt > CPU_HPPA_CLICKS_PER_TICK)
166    {
167        Clock_clicks_interrupt = itimer_value + 1000;
168        /* XXX: count these! this should never happen :-) */
169    }
170
171    set_itimer((rtems_unsigned32) Clock_clicks_interrupt);
172
173    Clock_driver_ticks++;
174
175    if (Clock_isrs == 1)
176    {
177        rtems_clock_tick();
178        Clock_isrs = BSP_Configuration.microseconds_per_tick / 10000;
179        if (Clock_isrs == 0)
180            Clock_isrs = 1;
181    }
182    else
183        Clock_isrs--;
184}
185
186/*
187 * Called via atexit()
188 * Remove the clock interrupt handler by setting handler to NULL
189 */
190
191void
192Clock_exit(void)
193{
194    if ( BSP_Configuration.ticks_per_timeslice )
195    {
196        (void) set_vector(0, HPPA_INTERRUPT_EXTERNAL_INTERVAL_TIMER, 1);
197    }
198}
199
200/*
201 * spin delay for specified number of microseconds
202 * used by RTEMS delay macro
203 */
204
205void
206Clock_delay(rtems_unsigned32 microseconds)
207{
208    rtems_unsigned64 future_time;
209
210    (void) Clock_read_itimer();
211    future_time = Clock_clicks +
212      ((rtems_unsigned64) microseconds) *
213        Cpu_table.itimer_clicks_per_microsecond;
214
215    for (;;)
216    {
217        (void) Clock_read_itimer();
218        if (future_time <= Clock_clicks)
219            break;
220    }
221}
222
223rtems_device_driver Clock_initialize(
224  rtems_device_major_number major,
225  rtems_device_minor_number minor,
226  void *pargp
227)
228{
229    Install_clock(Clock_isr);
230
231    /*
232     * make major/minor avail to others such as shared memory driver
233     */
234    rtems_clock_major = major;
235    rtems_clock_minor = minor;
236
237    return RTEMS_SUCCESSFUL;
238}
239
240rtems_device_driver Clock_control(
241  rtems_device_major_number major,
242  rtems_device_minor_number minor,
243  void *pargp
244)
245{
246    rtems_libio_ioctl_args_t *args = pargp;
247
248    if (args == 0)
249        goto done;
250
251    /*
252     * This is hokey, but until we get a defined interface
253     * to do this, it will just be this simple...
254     */
255
256    if (args->command == rtems_build_name('I', 'S', 'R', ' '))
257    {
258        Clock_isr(HPPA_INTERRUPT_EXTERNAL_INTERVAL_TIMER);
259    }
260    else if (args->command == rtems_build_name('N', 'E', 'W', ' '))
261    {
262        ReInstall_clock(args->buffer);
263    }
264   
265done:
266    return RTEMS_SUCCESSFUL;
267}
Note: See TracBrowser for help on using the repository browser.