arch/arm/mach-atmel/time.c

   1 /*
   2  *  linux/arch/armnommu/mach-atmel/time.c
   3  *
   4  *  Copyright (C) SAMSUNG ELECTRONICS
   5  *                    Hyok S. Choi <hyok.choi@samsung.com>
   6  *
   7  * This program is free software; you can redistribute it and/or modify
   8  * it under the terms of the GNU General Public License as published by
   9  * the Free Software Foundation; either version 2 of the License, or
  10  * (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, MA  02111-1307  USA
  20  */
  21 #include <linux/kernel.h>
  22 #include <linux/sched.h>
  23 #include <linux/init.h>
  24 #include <linux/interrupt.h>
  25 #include <asm/system.h>
  26 #include <asm/leds.h>
  27 #include <asm/mach-types.h>
  28
  29 #include <asm/io.h>
  30 #include <asm/irq.h>
  31 #include <asm/mach/time.h>
  32 #include <asm/arch/time.h>
  33
  34 unsigned long atmel_gettimeoffset (void)
  35 {
  36         volatile struct at91_timers* tt = (struct at91_timers*) (AT91_TC_BASE);
  37         volatile struct at91_timer_channel* tc = &tt->chans[KERNEL_TIMER].ch;
  38         return tc->cv * (1000*1000)/(ARM_CLK/128);
  39 }
  40
  41 static irqreturn_t
  42 atmel_timer_interrupt(int irq, void *dev_id)
  43 {
  44         /* Clear the timer status interrupt. */
  45         volatile struct at91_timers* tt = (struct at91_timers*) (AT91_TC_BASE);
  46         volatile struct at91_timer_channel* tc = &tt->chans[KERNEL_TIMER].ch;
  47         (void)tc->sr;
  48
  49         timer_tick();
  50         return IRQ_HANDLED;
  51 }
  52
  53 static struct irqaction atmel_timer_irq = {
  54         .name           = "ATMEL Timer Tick",
  55         .flags          = IRQF_DISABLED | IRQF_TIMER,
  56         .handler        = atmel_timer_interrupt
  57 };
  58
  59 /*
  60  * Set up timer interrupt, and return the current time in seconds.
  61  */
  62
  63 void __init  atmel_time_init (void)
  64 {
  65         register volatile struct at91_timers* tt = (struct at91_timers*) (AT91_TC_BASE);
  66         register volatile struct at91_timer_channel* tc = &tt->chans[KERNEL_TIMER].ch;
  67         unsigned long v;
  68
  69         /* enable Kernel timer */
  70         HW_AT91_TIMER_INIT(KERNEL_TIMER)
  71
  72         /* No SYNC */
  73         tt->bcr = 0;
  74         /* program NO signal on XC1 */
  75         v = tt->bmr;
  76         v &= ~TCNXCNS(KERNEL_TIMER,3);
  77         v |= TCNXCNS(KERNEL_TIMER,1);
  78         tt->bmr = v;
  79
  80         tc->ccr = 2;  /* disable the channel */
  81
  82         /* select ACLK/128 as inupt frequency for TC1 and enable CPCTRG */
  83         tc->cmr = 3 | (1 << 14);
  84
  85         tc->idr = ~0ul;  /* disable all interrupt */
  86         tc->rc = ((ARM_CLK/128)/HZ - 1);   /* load the count limit into the CR register */
  87         tc->ier = TC_CPCS;  /* enable CPCS interrupt */
  88
  89         /*
  90          * @todo do those really need to be function pointers ?
  91          */
  92         atmel_timer_irq.handler = atmel_timer_interrupt;
  93
  94         /* set up the interrupt */
  95         setup_irq(KERNEL_TIMER_IRQ_NUM, &atmel_timer_irq);
  96
  97         /* enable the channel */
  98         tc->ccr = TC_SWTRG|TC_CLKEN;
  99 }
 100
 101 struct sys_timer atmel_timer = {
 102         .init           = atmel_time_init,
 103         .offset         = atmel_gettimeoffset,
 104 };