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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; either version 2 of the License, or
   7  * (at your option) any later version.
   8  *
   9  * This program is distributed in the hope that it will be useful, but
  10  * WITHOUT ANY WARRANTY; without even the implied warranty of
  11  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  12  * General Public License for more details.
  13  *
  14  * You should have received a copy of the GNU General Public License along
  15  * with this program; if not, write to the Free Software Foundation, Inc.,
  16  * 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA.
  17  */
  18
  19 #include <ao.h>
  20 #include <ao_fast_timer.h>
  21
  22 static void (*ao_fast_timer_callback[AO_FAST_TIMER_MAX])(void);
  23 static uint8_t ao_fast_timer_count;
  24 static uint8_t ao_fast_timer_users;
  25
  26 static void
  27 ao_fast_timer_enable(void)
  28 {
  29         lpc_ct16b0.tcr = ((1 << LPC_CT16B_TCR_CEN) |
  30                           (1 << LPC_CT16B_TCR_CRST));
  31 }
  32
  33 static void
  34 ao_fast_timer_disable(void)
  35 {
  36         lpc_ct16b0.tcr = ((0 << LPC_CT16B_TCR_CEN) |
  37                           (0 << LPC_CT16B_TCR_CRST));
  38 }
  39
  40 void
  41 ao_fast_timer_on(void (*callback)(void))
  42 {
  43         ao_fast_timer_callback[ao_fast_timer_count] = callback;
  44         if (!ao_fast_timer_count++)
  45                 ao_fast_timer_enable();
  46 }
  47
  48 void
  49 ao_fast_timer_off(void (*callback)(void))
  50 {
  51         uint8_t n;
  52
  53         for (n = 0; n < ao_fast_timer_count; n++)
  54                 if (ao_fast_timer_callback[n] == callback) {
  55                         for (; n < ao_fast_timer_count-1; n++) {
  56                                 ao_fast_timer_callback[n] = ao_fast_timer_callback[n+1];
  57                         }
  58                         if (!--ao_fast_timer_count)
  59                                 ao_fast_timer_disable();
  60                         break;
  61                 }
  62 }
  63
  64 void lpc_ct16b0_isr(void)
  65 {
  66         uint32_t        v = lpc_ct16b0.ir;
  67         int             i;
  68
  69         lpc_ct16b0.ir = v;
  70         if (v & (1 << LPC_CT16B_IR_MR0INT)) {
  71                 for (i = 0; i < ao_fast_timer_count; i++)
  72                         (*ao_fast_timer_callback[i])();
  73         }
  74 }
  75
  76 #ifndef FAST_TIMER_FREQ
  77 #define FAST_TIMER_FREQ 10000
  78 #endif
  79
  80 #define TIMER_FAST      (AO_LPC_SYSCLK / FAST_TIMER_FREQ)
  81
  82 void
  83 ao_fast_timer_init(void)
  84 {
  85         if (!ao_fast_timer_users) {
  86
  87                 lpc_nvic_set_enable(LPC_ISR_CT16B0_POS);
  88                 lpc_nvic_set_priority(LPC_ISR_CT16B0_POS, AO_LPC_NVIC_CLOCK_PRIORITY);
  89                 /* Turn on 16-bit timer CT16B0 */
  90
  91                 lpc_scb.sysahbclkctrl |= 1 << LPC_SCB_SYSAHBCLKCTRL_CT16B0;
  92
  93                 /* Disable timer */
  94                 lpc_ct16b0.tcr = 0;
  95
  96                 /* scale factor 1 */
  97                 lpc_ct16b0.pr = 0;
  98                 lpc_ct16b0.pc = 0;
  99
 100                 lpc_ct16b0.mcr = ((1 << LPC_CT16B_MCR_MR0I) |
 101                                   (1 << LPC_CT16B_MCR_MR0R));
 102
 103                 lpc_ct16b0.mr[0] = TIMER_FAST;
 104
 105                 ao_fast_timer_disable();
 106         }
 107         if (ao_fast_timer_users == AO_FAST_TIMER_MAX)
 108                 ao_panic(AO_PANIC_FAST_TIMER);
 109         ao_fast_timer_users++;
 110 }
 111