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/irq.h>
  50 #include <asm/mach/irq.h>
  51 #include <asm/mach/time.h>
  52
  53 #include <plat/counter-32k.h>
  54
  55 #include <mach/hardware.h>
  56
  57 #include "common.h"
  58
  59 /*
  60  * ---------------------------------------------------------------------------
  61  * 32KHz OS timer
  62  *
  63  * This currently works only on 16xx, as 1510 does not have the continuous
  64  * 32KHz synchronous timer. The 32KHz synchronous timer is used to keep track
  65  * of time in addition to the 32KHz OS timer. Using only the 32KHz OS timer
  66  * on 1510 would be possible, but the timer would not be as accurate as
  67  * with the 32KHz synchronized timer.
  68  * ---------------------------------------------------------------------------
  69  */
  70
  71 /* 16xx specific defines */
  72 #define OMAP1_32K_TIMER_BASE            0xfffb9000
  73 #define OMAP1_32KSYNC_TIMER_BASE        0xfffbc400
  74 #define OMAP1_32K_TIMER_CR              0x08
  75 #define OMAP1_32K_TIMER_TVR             0x00
  76 #define OMAP1_32K_TIMER_TCR             0x04
  77
  78 #define OMAP_32K_TICKS_PER_SEC          (32768)
  79
  80 /*
  81  * TRM says 1 / HZ = ( TVR + 1) / 32768, so TRV = (32768 / HZ) - 1
  82  * so with HZ = 128, TVR = 255.
  83  */
  84 #define OMAP_32K_TIMER_TICK_PERIOD      ((OMAP_32K_TICKS_PER_SEC / HZ) - 1)
  85
  86 #define JIFFIES_TO_HW_TICKS(nr_jiffies, clock_rate)                     \
  87                                 (((nr_jiffies) * (clock_rate)) / HZ)
  88
  89 static inline void omap_32k_timer_write(int val, int reg)
  90 {
  91         omap_writew(val, OMAP1_32K_TIMER_BASE + reg);
  92 }
  93
  94 static inline void omap_32k_timer_start(unsigned long load_val)
  95 {
  96         if (!load_val)
  97                 load_val = 1;
  98         omap_32k_timer_write(load_val, OMAP1_32K_TIMER_TVR);
  99         omap_32k_timer_write(0x0f, OMAP1_32K_TIMER_CR);
 100 }
 101
 102 static inline void omap_32k_timer_stop(void)
 103 {
 104         omap_32k_timer_write(0x0, OMAP1_32K_TIMER_CR);
 105 }
 106
 107 #define omap_32k_timer_ack_irq()
 108
 109 static int omap_32k_timer_set_next_event(unsigned long delta,
 110                                          struct clock_event_device *dev)
 111 {
 112         omap_32k_timer_start(delta);
 113
 114         return 0;
 115 }
 116
 117 static int omap_32k_timer_shutdown(struct clock_event_device *evt)
 118 {
 119         omap_32k_timer_stop();
 120         return 0;
 121 }
 122
 123 static int omap_32k_timer_set_periodic(struct clock_event_device *evt)
 124 {
 125         omap_32k_timer_stop();
 126         omap_32k_timer_start(OMAP_32K_TIMER_TICK_PERIOD);
 127         return 0;
 128 }
 129
 130 static struct clock_event_device clockevent_32k_timer = {
 131         .name                   = "32k-timer",
 132         .features               = CLOCK_EVT_FEAT_PERIODIC |
 133                                   CLOCK_EVT_FEAT_ONESHOT,
 134         .set_next_event         = omap_32k_timer_set_next_event,
 135         .set_state_shutdown     = omap_32k_timer_shutdown,
 136         .set_state_periodic     = omap_32k_timer_set_periodic,
 137         .set_state_oneshot      = omap_32k_timer_shutdown,
 138         .tick_resume            = omap_32k_timer_shutdown,
 139 };
 140
 141 static irqreturn_t omap_32k_timer_interrupt(int irq, void *dev_id)
 142 {
 143         struct clock_event_device *evt = &clockevent_32k_timer;
 144         omap_32k_timer_ack_irq();
 145
 146         evt->event_handler(evt);
 147
 148         return IRQ_HANDLED;
 149 }
 150
 151 static struct irqaction omap_32k_timer_irq = {
 152         .name           = "32KHz timer",
 153         .flags          = IRQF_TIMER | IRQF_IRQPOLL,
 154         .handler        = omap_32k_timer_interrupt,
 155 };
 156
 157 static __init void omap_init_32k_timer(void)
 158 {
 159         setup_irq(INT_OS_TIMER, &omap_32k_timer_irq);
 160
 161         clockevent_32k_timer.cpumask = cpumask_of(0);
 162         clockevents_config_and_register(&clockevent_32k_timer,
 163                                         OMAP_32K_TICKS_PER_SEC, 1, 0xfffffffe);
 164 }
 165
 166 /*
 167  * ---------------------------------------------------------------------------
 168  * Timer initialization
 169  * ---------------------------------------------------------------------------
 170  */
 171 int __init omap_32k_timer_init(void)
 172 {
 173         int ret = -ENODEV;
 174
 175         if (cpu_is_omap16xx()) {
 176                 void __iomem *base;
 177                 struct clk *sync32k_ick;
 178
 179                 base = ioremap(OMAP1_32KSYNC_TIMER_BASE, SZ_1K);
 180                 if (!base) {
 181                         pr_err("32k_counter: failed to map base addr\n");
 182                         return -ENODEV;
 183                 }
 184
 185                 sync32k_ick = clk_get(NULL, "omap_32ksync_ick");
 186                 if (!IS_ERR(sync32k_ick))
 187                         clk_enable(sync32k_ick);
 188
 189                 ret = omap_init_clocksource_32k(base);
 190         }
 191
 192         if (!ret)
 193                 omap_init_32k_timer();
 194
 195         return ret;
 196 }