arch/arm/mach-clps711x/time.c

   1 /*
   2  *  linux/arch/arm/mach-clps711x/time.c
   3  *
   4  *  Copyright (C) 2001 Deep Blue Solutions Ltd.
   5  *
   6  * This program is free software; you can redistribute it and/or modify
   7  * it under the terms of the GNU General Public License version 2 as
   8  * published by the Free Software Foundation.
   9  *
  10  * This program is distributed in the hope that it will be useful,
  11  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  12  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  13  * GNU General Public License for more details.
  14  *
  15  * You should have received a copy of the GNU General Public License
  16  * along with this program; if not, write to the Free Software
  17  * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
  18  */
  19 #include <linux/timex.h>
  20 #include <linux/init.h>
  21 #include <linux/interrupt.h>
  22 #include <linux/sched.h>
  23
  24 #include <asm/hardware.h>
  25 #include <asm/irq.h>
  26 #include <asm/leds.h>
  27 #include <asm/io.h>
  28 #include <asm/hardware/clps7111.h>
  29
  30 #include <asm/mach/time.h>
  31
  32
  33 /*
  34  * gettimeoffset() returns time since last timer tick, in usecs.
  35  *
  36  * 'LATCH' is hwclock ticks (see CLOCK_TICK_RATE in timex.h) per jiffy.
  37  * 'tick' is usecs per jiffy.
  38  */
  39 static unsigned long clps711x_gettimeoffset(void)
  40 {
  41         unsigned long hwticks;
  42         hwticks = LATCH - (clps_readl(TC2D) & 0xffff);  /* since last underflow */
  43         return (hwticks * (tick_nsec / 1000)) / LATCH;
  44 }
  45
  46 /*
  47  * IRQ handler for the timer
  48  */
  49 static irqreturn_t
  50 p720t_timer_interrupt(int irq, void *dev_id, struct pt_regs *regs)
  51 {
  52         write_seqlock(&xtime_lock);
  53         timer_tick(regs);
  54         write_sequnlock(&xtime_lock);
  55         return IRQ_HANDLED;
  56 }
  57
  58 static struct irqaction clps711x_timer_irq = {
  59         .name           = "CLPS711x Timer Tick",
  60         .flags          = SA_INTERRUPT,
  61         .handler        = p720t_timer_interrupt
  62 };
  63
  64 static void __init clps711x_timer_init(void)
  65 {
  66         struct timespec tv;
  67         unsigned int syscon;
  68
  69         syscon = clps_readl(SYSCON1);
  70         syscon |= SYSCON1_TC2S | SYSCON1_TC2M;
  71         clps_writel(syscon, SYSCON1);
  72
  73         clps_writel(LATCH-1, TC2D); /* 512kHz / 100Hz - 1 */
  74
  75         setup_irq(IRQ_TC2OI, &clps711x_timer_irq);
  76
  77         tv.tv_nsec = 0;
  78         tv.tv_sec = clps_readl(RTCDR);
  79         do_settimeofday(&tv);
  80 }
  81
  82 struct sys_timer clps711x_timer = {
  83         .init           = clps711x_timer_init,
  84         .offset         = clps711x_gettimeoffset,
  85 };