cpu/at32ap/interrupts.c

   1 /*
   2  * Copyright (C) 2004-2006 Atmel Corporation
   3  *
   4  * See file CREDITS for list of people who contributed to this
   5  * project.
   6  *
   7  * This program is free software; you can redistribute it and/or
   8  * modify it under the terms of the GNU General Public License as
   9  * published by the Free Software Foundation; either version 2 of
  10  * the License, or (at your option) any later version.
  11  *
  12  * This program is distributed in the hope that it will be useful,
  13  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  14  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  15  * GNU General Public License for more details.
  16  *
  17  * You should have received a copy of the GNU General Public License
  18  * along with this program; if not, write to the Free Software
  19  * Foundation, Inc., 59 Temple Place, Suite 330, Boston,
  20  * MA 02111-1307 USA
  21  */
  22 #include <common.h>
  23 #include <div64.h>
  24
  25 #include <asm/errno.h>
  26 #include <asm/io.h>
  27 #include <asm/processor.h>
  28 #include <asm/sysreg.h>
  29
  30 #include <asm/arch/memory-map.h>
  31
  32 #define HANDLER_MASK    0x00ffffff
  33 #define INTLEV_SHIFT    30
  34 #define INTLEV_MASK     0x00000003
  35
  36 DECLARE_GLOBAL_DATA_PTR;
  37
  38 /* Incremented whenever COUNT reaches 0xffffffff by timer_interrupt_handler */
  39 volatile unsigned long timer_overflow;
  40
  41 /*
  42  * Instead of dividing by get_tbclk(), multiply by this constant and
  43  * right-shift the result by 32 bits.
  44  */
  45 static unsigned long tb_factor;
  46
  47 unsigned long get_tbclk(void)
  48 {
  49         return gd->cpu_hz;
  50 }
  51
  52 unsigned long long get_ticks(void)
  53 {
  54         unsigned long lo, hi_now, hi_prev;
  55
  56         do {
  57                 hi_prev = timer_overflow;
  58                 lo = sysreg_read(COUNT);
  59                 hi_now = timer_overflow;
  60         } while (hi_prev != hi_now);
  61
  62         return ((unsigned long long)hi_now << 32) | lo;
  63 }
  64
  65 void reset_timer(void)
  66 {
  67         sysreg_write(COUNT, 0);
  68         cpu_sync_pipeline();    /* process any pending interrupts */
  69         timer_overflow = 0;
  70 }
  71
  72 unsigned long get_timer(unsigned long base)
  73 {
  74         u64 now = get_ticks();
  75
  76         now *= tb_factor;
  77         return (unsigned long)(now >> 32) - base;
  78 }
  79
  80 void set_timer(unsigned long t)
  81 {
  82         unsigned long long ticks = t;
  83         unsigned long lo, hi, hi_new;
  84
  85         ticks = (ticks * get_tbclk()) / CFG_HZ;
  86         hi = ticks >> 32;
  87         lo = ticks & 0xffffffffUL;
  88
  89         do {
  90                 timer_overflow = hi;
  91                 sysreg_write(COUNT, lo);
  92                 hi_new = timer_overflow;
  93         } while (hi_new != hi);
  94 }
  95
  96 /*
  97  * For short delays only. It will overflow after a few seconds.
  98  */
  99 void udelay(unsigned long usec)
 100 {
 101         unsigned long now, end;
 102
 103         now = sysreg_read(COUNT);
 104
 105         end = ((usec * (get_tbclk() / 10000)) + 50) / 100;
 106         end += now;
 107
 108         while (now > end)
 109                 now = sysreg_read(COUNT);
 110
 111         while (now < end)
 112                 now = sysreg_read(COUNT);
 113 }
 114
 115 static int set_interrupt_handler(unsigned int nr, void (*handler)(void),
 116                                  unsigned int priority)
 117 {
 118         extern void _evba(void);
 119         unsigned long intpr;
 120         unsigned long handler_addr = (unsigned long)handler;
 121
 122         handler_addr -= (unsigned long)&_evba;
 123
 124         if ((handler_addr & HANDLER_MASK) != handler_addr
 125             || (priority & INTLEV_MASK) != priority)
 126                 return -EINVAL;
 127
 128         intpr = (handler_addr & HANDLER_MASK);
 129         intpr |= (priority & INTLEV_MASK) << INTLEV_SHIFT;
 130         writel(intpr, (void *)INTC_BASE + 4 * nr);
 131
 132         return 0;
 133 }
 134
 135 void timer_init(void)
 136 {
 137         extern void timer_interrupt_handler(void);
 138         u64 tmp;
 139
 140         sysreg_write(COUNT, 0);
 141
 142         tmp = (u64)CFG_HZ << 32;
 143         tmp += gd->cpu_hz / 2;
 144         do_div(tmp, gd->cpu_hz);
 145         tb_factor = (u32)tmp;
 146
 147         if (set_interrupt_handler(0, &timer_interrupt_handler, 3))
 148                 return;
 149
 150         /* For all practical purposes, this gives us an overflow interrupt */
 151         sysreg_write(COMPARE, 0xffffffff);
 152 }