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   1 /*
   2  * Copyright © 2016 Keith Packard <keithp@keithp.com>
   3  *
   4  * This program is free software; you can redistribute it and/or modify
   5  * it under the terms of the GNU General Public License as published by
   6  * the Free Software Foundation; version 2 of the License.
   7  *
   8  * This program is distributed in the hope that it will be useful, but
   9  * WITHOUT ANY WARRANTY; without even the implied warranty of
  10  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  11  * General Public License for more details.
  12  *
  13  * You should have received a copy of the GNU General Public License along
  14  * with this program; if not, write to the Free Software Foundation, Inc.,
  15  * 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA.
  16  */
  17
  18 #include <ao.h>
  19 #include <ao_fast_timer.h>
  20
  21 static void (*ao_fast_timer_callback[AO_FAST_TIMER_MAX])(void);
  22 static uint8_t ao_fast_timer_count;
  23 static uint8_t ao_fast_timer_users;
  24
  25 static void
  26 ao_fast_timer_enable(void)
  27 {
  28         lpc_ct16b0.tcr = ((1 << LPC_CT16B_TCR_CEN) |
  29                           (1 << LPC_CT16B_TCR_CRST));
  30 }
  31
  32 static void
  33 ao_fast_timer_disable(void)
  34 {
  35         lpc_ct16b0.tcr = ((0 << LPC_CT16B_TCR_CEN) |
  36                           (0 << LPC_CT16B_TCR_CRST));
  37 }
  38
  39 void
  40 ao_fast_timer_on(void (*callback)(void))
  41 {
  42         ao_fast_timer_callback[ao_fast_timer_count] = callback;
  43         if (!ao_fast_timer_count++)
  44                 ao_fast_timer_enable();
  45 }
  46
  47 void
  48 ao_fast_timer_off(void (*callback)(void))
  49 {
  50         uint8_t n;
  51
  52         for (n = 0; n < ao_fast_timer_count; n++)
  53                 if (ao_fast_timer_callback[n] == callback) {
  54                         for (; n < ao_fast_timer_count-1; n++) {
  55                                 ao_fast_timer_callback[n] = ao_fast_timer_callback[n+1];
  56                         }
  57                         if (!--ao_fast_timer_count)
  58                                 ao_fast_timer_disable();
  59                         break;
  60                 }
  61 }
  62
  63 void lpc_ct16b0_isr(void)
  64 {
  65         uint32_t        v = lpc_ct16b0.ir;
  66         int             i;
  67
  68         lpc_ct16b0.ir = v;
  69         if (v & (1 << LPC_CT16B_IR_MR0INT)) {
  70                 for (i = 0; i < ao_fast_timer_count; i++)
  71                         (*ao_fast_timer_callback[i])();
  72         }
  73 }
  74
  75 #ifndef FAST_TIMER_FREQ
  76 #define FAST_TIMER_FREQ 10000
  77 #endif
  78
  79 #define TIMER_FAST      (AO_LPC_SYSCLK / FAST_TIMER_FREQ)
  80
  81 void
  82 ao_fast_timer_init(void)
  83 {
  84         if (!ao_fast_timer_users) {
  85
  86                 lpc_nvic_set_enable(LPC_ISR_CT16B0_POS);
  87                 lpc_nvic_set_priority(LPC_ISR_CT16B0_POS, AO_LPC_NVIC_CLOCK_PRIORITY);
  88                 /* Turn on 16-bit timer CT16B0 */
  89
  90                 lpc_scb.sysahbclkctrl |= 1 << LPC_SCB_SYSAHBCLKCTRL_CT16B0;
  91
  92                 /* Disable timer */
  93                 lpc_ct16b0.tcr = 0;
  94
  95                 /* scale factor 1 */
  96                 lpc_ct16b0.pr = 0;
  97                 lpc_ct16b0.pc = 0;
  98
  99                 lpc_ct16b0.mcr = ((1 << LPC_CT16B_MCR_MR0I) |
 100                                   (1 << LPC_CT16B_MCR_MR0R));
 101
 102                 lpc_ct16b0.mr[0] = TIMER_FAST;
 103
 104                 ao_fast_timer_disable();
 105         }
 106         if (ao_fast_timer_users == AO_FAST_TIMER_MAX)
 107                 ao_panic(AO_PANIC_FAST_TIMER);
 108         ao_fast_timer_users++;
 109 }
 110