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 #include <linux/irq.h>
  23 #include <linux/clocksource.h>
  24 #include <linux/clockchips.h>
  25 #include <linux/io.h>
  26
  27 #include <mach/hardware.h>
  28 #include <asm/mach/time.h>
  29 #include <mach/netx-regs.h>
  30
  31 #define TIMER_CLOCKEVENT 0
  32 #define TIMER_CLOCKSOURCE 1
  33
  34 static void netx_set_mode(enum clock_event_mode mode,
  35                 struct clock_event_device *clk)
  36 {
  37         u32 tmode;
  38
  39         /* disable timer */
  40         writel(0, NETX_GPIO_COUNTER_CTRL(TIMER_CLOCKEVENT));
  41
  42         switch (mode) {
  43         case CLOCK_EVT_MODE_PERIODIC:
  44                 writel(LATCH, NETX_GPIO_COUNTER_MAX(TIMER_CLOCKEVENT));
  45                 tmode = NETX_GPIO_COUNTER_CTRL_RST_EN |
  46                         NETX_GPIO_COUNTER_CTRL_IRQ_EN |
  47                         NETX_GPIO_COUNTER_CTRL_RUN;
  48                 break;
  49
  50         case CLOCK_EVT_MODE_ONESHOT:
  51                 writel(0, NETX_GPIO_COUNTER_MAX(TIMER_CLOCKEVENT));
  52                 tmode = NETX_GPIO_COUNTER_CTRL_IRQ_EN |
  53                         NETX_GPIO_COUNTER_CTRL_RUN;
  54                 break;
  55
  56         default:
  57                 WARN(1, "%s: unhandled mode %d\n", __func__, mode);
  58                 /* fall through */
  59
  60         case CLOCK_EVT_MODE_SHUTDOWN:
  61         case CLOCK_EVT_MODE_UNUSED:
  62         case CLOCK_EVT_MODE_RESUME:
  63                 tmode = 0;
  64                 break;
  65         }
  66
  67         writel(tmode, NETX_GPIO_COUNTER_CTRL(TIMER_CLOCKEVENT));
  68 }
  69
  70 static int netx_set_next_event(unsigned long evt,
  71                 struct clock_event_device *clk)
  72 {
  73         writel(0 - evt, NETX_GPIO_COUNTER_CURRENT(TIMER_CLOCKEVENT));
  74         return 0;
  75 }
  76
  77 static struct clock_event_device netx_clockevent = {
  78         .name = "netx-timer" __stringify(TIMER_CLOCKEVENT),
  79         .shift = 32,
  80         .features = CLOCK_EVT_FEAT_PERIODIC | CLOCK_EVT_FEAT_ONESHOT,
  81         .set_next_event = netx_set_next_event,
  82         .set_mode = netx_set_mode,
  83 };
  84
  85 /*
  86  * IRQ handler for the timer
  87  */
  88 static irqreturn_t
  89 netx_timer_interrupt(int irq, void *dev_id)
  90 {
  91         struct clock_event_device *evt = &netx_clockevent;
  92
  93         /* acknowledge interrupt */
  94         writel(COUNTER_BIT(0), NETX_GPIO_IRQ);
  95
  96         evt->event_handler(evt);
  97
  98         return IRQ_HANDLED;
  99 }
 100
 101 static struct irqaction netx_timer_irq = {
 102         .name           = "NetX Timer Tick",
 103         .flags          = IRQF_DISABLED | IRQF_TIMER | IRQF_IRQPOLL,
 104         .handler        = netx_timer_interrupt,
 105 };
 106
 107 cycle_t netx_get_cycles(struct clocksource *cs)
 108 {
 109         return readl(NETX_GPIO_COUNTER_CURRENT(TIMER_CLOCKSOURCE));
 110 }
 111
 112 static struct clocksource clocksource_netx = {
 113         .name           = "netx_timer",
 114         .rating         = 200,
 115         .read           = netx_get_cycles,
 116         .mask           = CLOCKSOURCE_MASK(32),
 117         .flags          = CLOCK_SOURCE_IS_CONTINUOUS,
 118 };
 119
 120 /*
 121  * Set up timer interrupt
 122  */
 123 static void __init netx_timer_init(void)
 124 {
 125         /* disable timer initially */
 126         writel(0, NETX_GPIO_COUNTER_CTRL(0));
 127
 128         /* Reset the timer value to zero */
 129         writel(0, NETX_GPIO_COUNTER_CURRENT(0));
 130
 131         writel(LATCH, NETX_GPIO_COUNTER_MAX(0));
 132
 133         /* acknowledge interrupt */
 134         writel(COUNTER_BIT(0), NETX_GPIO_IRQ);
 135
 136         /* Enable the interrupt in the specific timer
 137          * register and start timer
 138          */
 139         writel(COUNTER_BIT(0), NETX_GPIO_IRQ_ENABLE);
 140         writel(NETX_GPIO_COUNTER_CTRL_IRQ_EN | NETX_GPIO_COUNTER_CTRL_RUN,
 141                         NETX_GPIO_COUNTER_CTRL(0));
 142
 143         setup_irq(NETX_IRQ_TIMER0, &netx_timer_irq);
 144
 145         /* Setup timer one for clocksource */
 146         writel(0, NETX_GPIO_COUNTER_CTRL(TIMER_CLOCKSOURCE));
 147         writel(0, NETX_GPIO_COUNTER_CURRENT(TIMER_CLOCKSOURCE));
 148         writel(0xffffffff, NETX_GPIO_COUNTER_MAX(TIMER_CLOCKSOURCE));
 149
 150         writel(NETX_GPIO_COUNTER_CTRL_RUN,
 151                         NETX_GPIO_COUNTER_CTRL(TIMER_CLOCKSOURCE));
 152
 153         clocksource_register_hz(&clocksource_netx, CLOCK_TICK_RATE);
 154
 155         netx_clockevent.mult = div_sc(CLOCK_TICK_RATE, NSEC_PER_SEC,
 156                         netx_clockevent.shift);
 157         netx_clockevent.max_delta_ns =
 158                 clockevent_delta2ns(0xfffffffe, &netx_clockevent);
 159         /* with max_delta_ns >= delta2ns(0x800) the system currently runs fine.
 160          * Adding some safety ... */
 161         netx_clockevent.min_delta_ns =
 162                 clockevent_delta2ns(0xa00, &netx_clockevent);
 163         netx_clockevent.cpumask = cpumask_of(0);
 164         clockevents_register_device(&netx_clockevent);
 165 }
 166
 167 struct sys_timer netx_timer = {
 168         .init           = netx_timer_init,
 169 };