arch/arm/mach-omap1/timer32k.c

   1 /*
   2  * linux/arch/arm/mach-omap1/timer32k.c
   3  *
   4  * OMAP 32K Timer
   5  *
   6  * Copyright (C) 2004 - 2005 Nokia Corporation
   7  * Partial timer rewrite and additional dynamic tick timer support by
   8  * Tony Lindgen <tony@atomide.com> and
   9  * Tuukka Tikkanen <tuukka.tikkanen@elektrobit.com>
  10  * OMAP Dual-mode timer framework support by Timo Teras
  11  *
  12  * MPU timer code based on the older MPU timer code for OMAP
  13  * Copyright (C) 2000 RidgeRun, Inc.
  14  * Author: Greg Lonnon <glonnon@ridgerun.com>
  15  *
  16  * This program is free software; you can redistribute it and/or modify it
  17  * under the terms of the GNU General Public License as published by the
  18  * Free Software Foundation; either version 2 of the License, or (at your
  19  * option) any later version.
  20  *
  21  * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESS OR IMPLIED
  22  * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
  23  * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN
  24  * NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
  25  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
  26  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
  27  * USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON
  28  * ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  29  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
  30  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  31  *
  32  * You should have received a copy of the  GNU General Public License along
  33  * with this program; if not, write  to the Free Software Foundation, Inc.,
  34  * 675 Mass Ave, Cambridge, MA 02139, USA.
  35  */
  36
  37 #include <linux/kernel.h>
  38 #include <linux/init.h>
  39 #include <linux/delay.h>
  40 #include <linux/interrupt.h>
  41 #include <linux/sched.h>
  42 #include <linux/spinlock.h>
  43 #include <linux/err.h>
  44 #include <linux/clk.h>
  45 #include <linux/clocksource.h>
  46 #include <linux/clockchips.h>
  47 #include <linux/io.h>
  48
  49 #include <asm/system.h>
  50 #include <mach/hardware.h>
  51 #include <asm/leds.h>
  52 #include <asm/irq.h>
  53 #include <asm/mach/irq.h>
  54 #include <asm/mach/time.h>
  55 #include <plat/common.h>
  56 #include <plat/dmtimer.h>
  57
  58 /*
  59  * ---------------------------------------------------------------------------
  60  * 32KHz OS timer
  61  *
  62  * This currently works only on 16xx, as 1510 does not have the continuous
  63  * 32KHz synchronous timer. The 32KHz synchronous timer is used to keep track
  64  * of time in addition to the 32KHz OS timer. Using only the 32KHz OS timer
  65  * on 1510 would be possible, but the timer would not be as accurate as
  66  * with the 32KHz synchronized timer.
  67  * ---------------------------------------------------------------------------
  68  */
  69
  70 /* 16xx specific defines */
  71 #define OMAP1_32K_TIMER_BASE            0xfffb9000
  72 #define OMAP1_32K_TIMER_CR              0x08
  73 #define OMAP1_32K_TIMER_TVR             0x00
  74 #define OMAP1_32K_TIMER_TCR             0x04
  75
  76 #define OMAP_32K_TICKS_PER_SEC          (32768)
  77
  78 /*
  79  * TRM says 1 / HZ = ( TVR + 1) / 32768, so TRV = (32768 / HZ) - 1
  80  * so with HZ = 128, TVR = 255.
  81  */
  82 #define OMAP_32K_TIMER_TICK_PERIOD      ((OMAP_32K_TICKS_PER_SEC / HZ) - 1)
  83
  84 #define JIFFIES_TO_HW_TICKS(nr_jiffies, clock_rate)                     \
  85                                 (((nr_jiffies) * (clock_rate)) / HZ)
  86
  87 static inline void omap_32k_timer_write(int val, int reg)
  88 {
  89         omap_writew(val, OMAP1_32K_TIMER_BASE + reg);
  90 }
  91
  92 static inline unsigned long omap_32k_timer_read(int reg)
  93 {
  94         return omap_readl(OMAP1_32K_TIMER_BASE + reg) & 0xffffff;
  95 }
  96
  97 static inline void omap_32k_timer_start(unsigned long load_val)
  98 {
  99         if (!load_val)
 100                 load_val = 1;
 101         omap_32k_timer_write(load_val, OMAP1_32K_TIMER_TVR);
 102         omap_32k_timer_write(0x0f, OMAP1_32K_TIMER_CR);
 103 }
 104
 105 static inline void omap_32k_timer_stop(void)
 106 {
 107         omap_32k_timer_write(0x0, OMAP1_32K_TIMER_CR);
 108 }
 109
 110 #define omap_32k_timer_ack_irq()
 111
 112 static int omap_32k_timer_set_next_event(unsigned long delta,
 113                                          struct clock_event_device *dev)
 114 {
 115         omap_32k_timer_start(delta);
 116
 117         return 0;
 118 }
 119
 120 static void omap_32k_timer_set_mode(enum clock_event_mode mode,
 121                                     struct clock_event_device *evt)
 122 {
 123         omap_32k_timer_stop();
 124
 125         switch (mode) {
 126         case CLOCK_EVT_MODE_PERIODIC:
 127                 omap_32k_timer_start(OMAP_32K_TIMER_TICK_PERIOD);
 128                 break;
 129         case CLOCK_EVT_MODE_ONESHOT:
 130         case CLOCK_EVT_MODE_UNUSED:
 131         case CLOCK_EVT_MODE_SHUTDOWN:
 132                 break;
 133         case CLOCK_EVT_MODE_RESUME:
 134                 break;
 135         }
 136 }
 137
 138 static struct clock_event_device clockevent_32k_timer = {
 139         .name           = "32k-timer",
 140         .features       = CLOCK_EVT_FEAT_PERIODIC | CLOCK_EVT_FEAT_ONESHOT,
 141         .shift          = 32,
 142         .set_next_event = omap_32k_timer_set_next_event,
 143         .set_mode       = omap_32k_timer_set_mode,
 144 };
 145
 146 static irqreturn_t omap_32k_timer_interrupt(int irq, void *dev_id)
 147 {
 148         struct clock_event_device *evt = &clockevent_32k_timer;
 149         omap_32k_timer_ack_irq();
 150
 151         evt->event_handler(evt);
 152
 153         return IRQ_HANDLED;
 154 }
 155
 156 static struct irqaction omap_32k_timer_irq = {
 157         .name           = "32KHz timer",
 158         .flags          = IRQF_DISABLED | IRQF_TIMER | IRQF_IRQPOLL,
 159         .handler        = omap_32k_timer_interrupt,
 160 };
 161
 162 static __init void omap_init_32k_timer(void)
 163 {
 164         setup_irq(INT_OS_TIMER, &omap_32k_timer_irq);
 165
 166         clockevent_32k_timer.mult = div_sc(OMAP_32K_TICKS_PER_SEC,
 167                                            NSEC_PER_SEC,
 168                                            clockevent_32k_timer.shift);
 169         clockevent_32k_timer.max_delta_ns =
 170                 clockevent_delta2ns(0xfffffffe, &clockevent_32k_timer);
 171         clockevent_32k_timer.min_delta_ns =
 172                 clockevent_delta2ns(1, &clockevent_32k_timer);
 173
 174         clockevent_32k_timer.cpumask = cpumask_of(0);
 175         clockevents_register_device(&clockevent_32k_timer);
 176 }
 177
 178 /*
 179  * ---------------------------------------------------------------------------
 180  * Timer initialization
 181  * ---------------------------------------------------------------------------
 182  */
 183 bool __init omap_32k_timer_init(void)
 184 {
 185         omap_init_clocksource_32k();
 186         omap_init_32k_timer();
 187
 188         return true;
 189 }