source: rtems/c/src/lib/libbsp/i386/pc386/clock/ckinit.c @ 6b54dcb

Last change on this file since 6b54dcb was 6b54dcb, checked in by Pavel Pisa <pisa@…>, on Oct 12, 2016 at 7:40:41 AM

bsps/i386: replace global interrupt disable by SMP build supporting locking.

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File size: 7.3 KB
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1/**
2 *  @file
3 *
4 *  Clock Tick Device Driver
5 *
6 *  History:
7 *    + Original driver was go32 clock by Joel Sherrill
8 *    + go32 clock driver hardware code was inserted into new
9 *      boilerplate when the pc386 BSP by:
10 *        Pedro Miguel Da Cruz Neto Romano <pmcnr@camoes.rnl.ist.utl.pt>
11 *        Jose Rufino <ruf@asterix.ist.utl.pt>
12 *    + Reworked by Joel Sherrill to use clock driver template.
13 *      This removes all boilerplate and leave original hardware
14 *      code I developed for the go32 BSP.
15 */
16
17/*
18 *  COPYRIGHT (c) 1989-2012.
19 *  On-Line Applications Research Corporation (OAR).
20 *
21 *  The license and distribution terms for this file may be
22 *  found in the file LICENSE in this distribution or at
23 *  http://www.rtems.org/license/LICENSE.
24 */
25
26#include <bsp.h>
27#include <bsp/irq-generic.h>
28#include <bspopts.h>
29#include <libcpu/cpuModel.h>
30#include <assert.h>
31#include <rtems/timecounter.h>
32
33#define CLOCK_VECTOR 0
34
35volatile uint32_t pc386_microseconds_per_isr;
36volatile uint32_t pc386_isrs_per_tick;
37uint32_t pc386_clock_click_count;
38
39/* forward declaration */
40void Clock_isr(void *param);
41static void clockOff(void);
42static void Clock_isr_handler(void *param);
43
44/*
45 * Roughly the number of cycles per second. Note that these
46 * will be wildly inaccurate if the chip speed changes due to power saving
47 * or thermal modes.
48 *
49 * NOTE: These are only used when the TSC method is used.
50 */
51static uint64_t pc586_tsc_frequency;
52
53static struct timecounter pc386_tc;
54
55/* this driver may need to count ISRs per tick */
56#define CLOCK_DRIVER_ISRS_PER_TICK       1
57#define CLOCK_DRIVER_ISRS_PER_TICK_VALUE pc386_isrs_per_tick
58
59extern volatile uint32_t Clock_driver_ticks;
60
61#define READ_8254( _lsb, _msb )                               \
62  do { outport_byte(TIMER_MODE, TIMER_SEL0|TIMER_LATCH);      \
63     inport_byte(TIMER_CNTR0, _lsb);                          \
64     inport_byte(TIMER_CNTR0, _msb);                          \
65  } while (0)
66
67
68#ifdef RTEMS_SMP
69#define Clock_driver_support_at_tick() \
70  _SMP_Send_message_broadcast(SMP_MESSAGE_CLOCK_TICK)
71#endif
72
73#define Clock_driver_support_install_isr( _new, _old ) \
74  do { \
75    _old = NULL; \
76  } while(0)
77
78static uint32_t pc386_get_timecount_tsc(struct timecounter *tc)
79{
80  return (uint32_t)rdtsc();
81}
82
83static uint32_t pc386_get_timecount_i8254(struct timecounter *tc)
84{
85  uint32_t                 irqs;
86  uint8_t                  lsb, msb;
87  rtems_interrupt_lock_context lock_context;
88
89  /*
90   * Fetch all the data in an interrupt critical section.
91   */
92
93  rtems_interrupt_lock_acquire(&rtems_i386_i8254_access_lock, &lock_context);
94
95    READ_8254(lsb, msb);
96    irqs = Clock_driver_ticks;
97
98  rtems_interrupt_lock_release(&rtems_i386_i8254_access_lock, &lock_context);
99
100  return (irqs + 1) * pc386_microseconds_per_isr - ((msb << 8) | lsb);
101}
102
103/*
104 * Calibrate CPU cycles per tick. Interrupts should be disabled.
105 */
106static void calibrate_tsc(void)
107{
108  uint64_t              begin_time;
109  uint8_t               then_lsb, then_msb, now_lsb, now_msb;
110  uint32_t              i;
111
112  /*
113   * We just reset the timer, so we know we're at the beginning of a tick.
114   */
115
116  /*
117   * Count cycles. Watching the timer introduces a several microsecond
118   * uncertaintity, so let it cook for a while and divide by the number of
119   * ticks actually executed.
120   */
121
122  begin_time = rdtsc();
123
124  for (i = rtems_clock_get_ticks_per_second() * pc386_isrs_per_tick;
125       i != 0; --i ) {
126    /* We know we've just completed a tick when timer goes from low to high */
127    then_lsb = then_msb = 0xff;
128    do {
129      READ_8254(now_lsb, now_msb);
130      if ((then_msb < now_msb) ||
131          ((then_msb == now_msb) && (then_lsb < now_lsb)))
132        break;
133      then_lsb = now_lsb;
134      then_msb = now_msb;
135    } while (1);
136  }
137
138  pc586_tsc_frequency = rdtsc() - begin_time;
139
140#if 0
141  printk( "CPU clock at %u MHz\n", (uint32_t)(pc586_tsc_frequency / 1000000));
142#endif
143}
144
145static void clockOn(void)
146{
147  rtems_interrupt_lock_context lock_context;
148  pc386_isrs_per_tick        = 1;
149  pc386_microseconds_per_isr = rtems_configuration_get_microseconds_per_tick();
150
151  while (US_TO_TICK(pc386_microseconds_per_isr) > 65535) {
152    pc386_isrs_per_tick  *= 10;
153    pc386_microseconds_per_isr /= 10;
154  }
155  pc386_clock_click_count = US_TO_TICK(pc386_microseconds_per_isr);
156
157  #if 0
158    printk( "configured usecs per tick=%d \n",
159      rtems_configuration_get_microseconds_per_tick() );
160    printk( "Microseconds per ISR =%d\n", pc386_microseconds_per_isr );
161    printk( "final ISRs per=%d\n", pc386_isrs_per_tick );
162    printk( "final timer counts=%d\n", pc386_clock_click_count );
163  #endif
164
165  rtems_interrupt_lock_acquire(&rtems_i386_i8254_access_lock, &lock_context);
166  outport_byte(TIMER_MODE, TIMER_SEL0|TIMER_16BIT|TIMER_RATEGEN);
167  outport_byte(TIMER_CNTR0, pc386_clock_click_count >> 0 & 0xff);
168  outport_byte(TIMER_CNTR0, pc386_clock_click_count >> 8 & 0xff);
169  rtems_interrupt_lock_release(&rtems_i386_i8254_access_lock, &lock_context);
170
171  bsp_interrupt_vector_enable( BSP_PERIODIC_TIMER - BSP_IRQ_VECTOR_BASE );
172
173  /*
174   * Now calibrate cycles per tick. Do this every time we
175   * turn the clock on in case the CPU clock speed has changed.
176   */
177  if ( x86_has_tsc() )
178    calibrate_tsc();
179}
180
181static void clockOff(void)
182{
183  rtems_interrupt_lock_context lock_context;
184  rtems_interrupt_lock_acquire(&rtems_i386_i8254_access_lock, &lock_context);
185  /* reset timer mode to standard (BIOS) value */
186  outport_byte(TIMER_MODE, TIMER_SEL0 | TIMER_16BIT | TIMER_RATEGEN);
187  outport_byte(TIMER_CNTR0, 0);
188  outport_byte(TIMER_CNTR0, 0);
189  rtems_interrupt_lock_release(&rtems_i386_i8254_access_lock, &lock_context);
190} /* Clock_exit */
191
192bool Clock_isr_enabled = false;
193static void Clock_isr_handler(void *param)
194{
195  if ( Clock_isr_enabled )
196    Clock_isr( param );
197}
198
199void Clock_driver_install_handler(void)
200{
201  rtems_status_code status;
202
203  status = rtems_interrupt_handler_install(
204    BSP_PERIODIC_TIMER,
205    "ckinit",
206    RTEMS_INTERRUPT_UNIQUE,
207    Clock_isr_handler,
208    NULL
209  );
210  assert(status == RTEMS_SUCCESSFUL);
211  clockOn();
212}
213
214#define Clock_driver_support_set_interrupt_affinity(online_processors) \
215  do { \
216    /* FIXME: Is there a way to do this on x86? */ \
217    (void) online_processors; \
218  } while (0)
219
220void Clock_driver_support_initialize_hardware(void)
221{
222  bool use_tsc = false;
223  bool use_8254 = false;
224
225  #if (CLOCK_DRIVER_USE_TSC == 1)
226    use_tsc = true;
227  #endif
228
229  #if (CLOCK_DRIVER_USE_8254 == 1)
230    use_8254 = true;
231  #endif
232
233  if ( !use_tsc && !use_8254 ) {
234    if ( x86_has_tsc() ) use_tsc  = true;
235    else                 use_8254 = true;
236  }
237
238  if ( use_8254 ) {
239    /* printk( "Use 8254\n" ); */
240    pc386_tc.tc_get_timecount = pc386_get_timecount_i8254;
241    pc386_tc.tc_counter_mask = 0xffffffff;
242    pc386_tc.tc_frequency = TIMER_TICK;
243  } else {
244    /* printk( "Use TSC\n" ); */
245    pc386_tc.tc_get_timecount = pc386_get_timecount_tsc;
246    pc386_tc.tc_counter_mask = 0xffffffff;
247    pc386_tc.tc_frequency = pc586_tsc_frequency;
248  }
249
250  pc386_tc.tc_quality = RTEMS_TIMECOUNTER_QUALITY_CLOCK_DRIVER;
251  rtems_timecounter_install(&pc386_tc);
252  Clock_isr_enabled = true;
253}
254
255#define Clock_driver_support_shutdown_hardware() \
256  do { \
257    rtems_status_code status; \
258    clockOff(); \
259    status = rtems_interrupt_handler_remove(  \
260      BSP_PERIODIC_TIMER, \
261      Clock_isr_handler,  \
262      NULL  \
263    );  \
264    assert(status == RTEMS_SUCCESSFUL); \
265  } while (0)
266
267#include "../../../shared/clockdrv_shell.h"
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