arch/arm/mach-netx/time.c

   1 /*
   2  * arch/arm/mach-netx/time.c
   3  *
   4  * Copyright (c) 2005 Sascha Hauer <s.hauer@pengutronix.de>, Pengutronix
   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
   8  * as 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
  20 #include <linux/init.h>
  21 #include <linux/interrupt.h>
  22
  23 #include <asm/hardware.h>
  24 #include <asm/io.h>
  25 #include <asm/mach/time.h>
  26 #include <asm/arch/netx-regs.h>
  27
  28 /*
  29  * Returns number of us since last clock interrupt.  Note that interrupts
  30  * will have been disabled by do_gettimeoffset()
  31  */
  32 static unsigned long netx_gettimeoffset(void)
  33 {
  34         return readl(NETX_GPIO_COUNTER_CURRENT(0)) / 100;
  35 }
  36
  37 /*
  38  * IRQ handler for the timer
  39  */
  40 static irqreturn_t
  41 netx_timer_interrupt(int irq, void *dev_id, struct pt_regs *regs)
  42 {
  43         write_seqlock(&xtime_lock);
  44
  45         timer_tick(regs);
  46         write_sequnlock(&xtime_lock);
  47
  48         /* acknowledge interrupt */
  49         writel(COUNTER_BIT(0), NETX_GPIO_IRQ);
  50
  51         return IRQ_HANDLED;
  52 }
  53
  54
  55 static struct irqaction netx_timer_irq = {
  56         .name           = "NetX Timer Tick",
  57         .flags          = IRQF_DISABLED | IRQF_TIMER,
  58         .handler        = netx_timer_interrupt,
  59 };
  60
  61 /*
  62  * Set up timer interrupt
  63  */
  64 static void __init netx_timer_init(void)
  65 {
  66         /* disable timer initially */
  67         writel(0, NETX_GPIO_COUNTER_CTRL(0));
  68
  69         /* Reset the timer value to zero */
  70         writel(0, NETX_GPIO_COUNTER_CURRENT(0));
  71
  72         writel(LATCH, NETX_GPIO_COUNTER_MAX(0));
  73
  74         /* acknowledge interrupt */
  75         writel(COUNTER_BIT(0), NETX_GPIO_IRQ);
  76
  77         /* Enable the interrupt in the specific timer register and start timer */
  78         writel(COUNTER_BIT(0), NETX_GPIO_IRQ_ENABLE);
  79         writel(NETX_GPIO_COUNTER_CTRL_IRQ_EN | NETX_GPIO_COUNTER_CTRL_RUN,
  80                 NETX_GPIO_COUNTER_CTRL(0));
  81
  82         setup_irq(NETX_IRQ_TIMER0, &netx_timer_irq);
  83 }
  84
  85 struct sys_timer netx_timer = {
  86         .init           = netx_timer_init,
  87         .offset         = netx_gettimeoffset,
  88 };