target/linux/ubicom32/files/arch/ubicom32/kernel/timer_device.c

   1 /*
   2  * arch/ubicom32/kernel/timer_device.c
   3  *   Implements a Ubicom32 clock device and event devices.
   4  *
   5  * (C) Copyright 2009, Ubicom, Inc.
   6  *
   7  * This file is part of the Ubicom32 Linux Kernel Port.
   8  *
   9  * The Ubicom32 Linux Kernel Port is free software: you can redistribute
  10  * it and/or modify it under the terms of the GNU General Public License
  11  * as published by the Free Software Foundation, either version 2 of the
  12  * License, or (at your option) any later version.
  13  *
  14  * The Ubicom32 Linux Kernel Port is distributed in the hope that it
  15  * will be useful, but WITHOUT ANY WARRANTY; without even the implied
  16  * warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See
  17  * the GNU General Public License for more details.
  18  *
  19  * You should have received a copy of the GNU General Public License
  20  * along with the Ubicom32 Linux Kernel Port.  If not,
  21  * see <http://www.gnu.org/licenses/>.
  22  *
  23  * Ubicom32 implementation derived from (with many thanks):
  24  *   arch/m68knommu
  25  *   arch/blackfin
  26  *   arch/parisc
  27  */
  28 #include <linux/types.h>
  29 #include <linux/clockchips.h>
  30 #include <linux/clocksource.h>
  31 #include <linux/spinlock.h>
  32 #include <asm/ip5000.h>
  33 #include <asm/machdep.h>
  34
  35 #if defined(CONFIG_SMP)
  36 #include <asm/smp.h>
  37 #endif
  38
  39 #if defined(CONFIG_GENERIC_CLOCKEVENTS_BROADCAST)
  40 #define MAX_TIMERS (2 + CONFIG_TIMER_EXTRA_ALLOC)
  41 #else
  42 #define MAX_TIMERS (NR_CPUS + CONFIG_TIMER_EXTRA_ALLOC)
  43 #endif
  44
  45 #if (MAX_TIMERS > 10)
  46 #error "Ubicom32 only has 10 timers"
  47 #endif
  48
  49 static unsigned int frequency;
  50 static struct clock_event_device timer_device_devs[MAX_TIMERS];
  51 static struct irqaction timer_device_irqs[MAX_TIMERS];
  52 static int timer_device_next_timer = 0;
  53
  54 DEFINE_SPINLOCK(timer_device_lock);
  55
  56 /*
  57  * timer_device_set_next_event()
  58  *      Cause the timer to go off "cycles" from now.
  59  */
  60 static int timer_device_set_next_event(unsigned long cycles, struct clock_event_device *dev)
  61 {
  62         timer_set(dev->irq, cycles);
  63         return 0;
  64 }
  65
  66 /*
  67  * timer_device_set_mode()
  68  *      Handle the mode switch for a clock event device.
  69  */
  70 static void timer_device_set_mode(enum clock_event_mode mode, struct clock_event_device *dev)
  71 {
  72         switch (mode) {
  73         case CLOCK_EVT_MODE_SHUTDOWN:
  74                 /*
  75                  * Make sure the vector is disabled
  76                  * until the next event is set.
  77                  */
  78                 printk(KERN_NOTICE "timer[%d]: shutdown\n", dev->irq);
  79                 ldsr_disable_vector(dev->irq);
  80                 break;
  81
  82         case CLOCK_EVT_MODE_ONESHOT:
  83                 /*
  84                  * Make sure the vector is disabled
  85                  * until the next event is set.
  86                  */
  87                 printk(KERN_NOTICE "timer[%d]: oneshot\n", dev->irq);
  88                 ldsr_disable_vector(dev->irq);
  89                 break;
  90
  91         case CLOCK_EVT_MODE_PERIODIC:
  92                 /*
  93                  * The periodic request is 1 per jiffies
  94                  */
  95                 printk(KERN_NOTICE "timer[%d]: periodic: %d cycles\n",
  96                         dev->irq, frequency / CONFIG_HZ);
  97                 timer_set(dev->irq, frequency / CONFIG_HZ);
  98                 break;
  99
 100         case CLOCK_EVT_MODE_UNUSED:
 101         case CLOCK_EVT_MODE_RESUME:
 102                 printk(KERN_WARNING "timer[%d]: unimplemented mode: %d\n",
 103                         dev->irq, mode);
 104                 break;
 105         };
 106 }
 107
 108 /*
 109  * timer_device_event()
 110  *      Call the device's event handler.
 111  *
 112  * The pointer is initialized by the generic Linux code
 113  * to the function to be called.
 114  */
 115 static irqreturn_t timer_device_event(int irq, void *dev_id)
 116 {
 117         struct clock_event_device *dev = (struct clock_event_device *)dev_id;
 118
 119         if (dev->mode == CLOCK_EVT_MODE_PERIODIC) {
 120                 /*
 121                  * The periodic request is 1 per jiffies
 122                  */
 123                 timer_reset(dev->irq, frequency / CONFIG_HZ);
 124         } else {
 125                 /*
 126                  * The timer will go off again at the rollover
 127                  * point.  We must disable the IRQ to prevent
 128                  * getting a spurious interrupt.
 129                  */
 130                 ldsr_disable_vector(dev->irq);
 131         }
 132
 133         if (!dev->event_handler) {
 134                 printk(KERN_CRIT "no registered event handler\n");
 135                 return IRQ_HANDLED;
 136         }
 137
 138         dev->event_handler(dev);
 139         return IRQ_HANDLED;
 140 }
 141
 142 /*
 143  * timer_device_clockbase_read()
 144  *      Provide a primary clocksource around the sysval timer.
 145  */
 146 static cycle_t timer_device_clockbase_read(void)
 147 {
 148         return (cycle_t)UBICOM32_IO_TIMER->sysval;
 149 }
 150
 151 /*
 152  * Primary Clock Source Description
 153  *
 154  * We use 24 for the shift factor because we want
 155  * to ensure there are less than 2^24 clocks
 156  * in a jiffie of 10 ms.
 157  */
 158 static struct clocksource timer_device_clockbase = {
 159         .name   = "sysval",
 160         .rating = 400,
 161         .flags  = CLOCK_SOURCE_IS_CONTINUOUS,
 162         .mask   = CLOCKSOURCE_MASK(32),
 163         .shift  = 24,
 164         .mult   = 0,
 165         .read   = timer_device_clockbase_read,
 166 };
 167
 168 /*
 169  * timer_device_alloc_event()
 170  *      Allocate a timer device event.
 171  */
 172 static int timer_device_alloc_event(const char *name, int cpuid, const cpumask_t *mask)
 173 {
 174         struct clock_event_device *dev;
 175         struct irqaction *action;
 176
 177         /*
 178          * Are we out of configured timers?
 179          */
 180         spin_lock(&timer_device_lock);
 181         if (timer_device_next_timer >= MAX_TIMERS) {
 182                 spin_unlock(&timer_device_lock);
 183                 printk(KERN_WARNING "out of timer event entries\n");
 184                 return -1;
 185         }
 186         dev = &timer_device_devs[timer_device_next_timer];
 187         action = &timer_device_irqs[timer_device_next_timer];
 188         timer_device_next_timer++;
 189         spin_unlock(&timer_device_lock);
 190
 191         /*
 192          * Now allocate a timer to ourselves.
 193          */
 194         dev->irq = timer_alloc();
 195         if (dev->irq == -1) {
 196                 spin_lock(&timer_device_lock);
 197                 timer_device_next_timer--;
 198                 spin_unlock(&timer_device_lock);
 199                 printk(KERN_WARNING "out of hardware timers\n");
 200                 return -1;
 201         }
 202
 203         /*
 204          * Init the IRQ action structure.  Make sure
 205          * this in place before you register the clock
 206          * event device.
 207          */
 208         action->name = name;
 209         action->flags = IRQF_DISABLED | IRQF_TIMER;
 210         action->handler = timer_device_event;
 211         cpumask_copy(&action->mask, mask);
 212         action->dev_id = dev;
 213         setup_irq(dev->irq, action);
 214         irq_set_affinity(dev->irq, mask);
 215         ldsr_disable_vector(dev->irq);
 216
 217         /*
 218          * init clock dev structure.
 219          *
 220          * The min_delta_ns is chosen to ensure that setting next
 221          * event will never be requested with too small of value.
 222          */
 223         dev->name = name;
 224         dev->rating = timer_device_clockbase.rating;
 225         dev->shift = timer_device_clockbase.shift;
 226         dev->features = CLOCK_EVT_FEAT_PERIODIC | CLOCK_EVT_FEAT_ONESHOT;
 227         dev->set_mode = timer_device_set_mode;
 228         dev->set_next_event = timer_device_set_next_event;
 229         dev->mult = div_sc(frequency, NSEC_PER_SEC, dev->shift);
 230         dev->max_delta_ns = clockevent_delta2ns(0xffffffff, dev);
 231         dev->min_delta_ns = clockevent_delta2ns(100, dev);
 232         dev->cpumask = mask;
 233         printk(KERN_NOTICE "timer[%d]: %s - created\n", dev->irq, dev->name);
 234
 235         /*
 236          * Now register the device.
 237          */
 238         clockevents_register_device(dev);
 239         return dev->irq;
 240 }
 241
 242 #if defined(CONFIG_LOCAL_TIMERS)
 243 /*
 244  * local_timer_setup()
 245  *      Allocation function for creating a per cpu local timer.
 246  */
 247 int __cpuinit local_timer_setup(unsigned int cpu)
 248 {
 249         return timer_device_alloc_event("timer-cpu", cpu, cpumask_of(cpu));
 250 }
 251 #endif
 252
 253 /*
 254  * timer_device_init()
 255  *      Create and init a generic clock driver for Ubicom32.
 256  */
 257 void timer_device_init(void)
 258 {
 259         int i;
 260
 261         /*
 262          * Get the frequency from the processor device tree node or use
 263          * the default if not available. We will store this as the frequency
 264          * of the timer to avoid future calculations.
 265          */
 266         frequency = processor_frequency();
 267         if (frequency == 0) {
 268                 frequency = CLOCK_TICK_RATE;
 269         }
 270
 271         /*
 272          * Setup the primary clock source around sysval.  Linux does not
 273          * supply a Mhz multiplier so convert down to khz.
 274          */
 275         timer_device_clockbase.mult =
 276                 clocksource_khz2mult(frequency / 1000,
 277                         timer_device_clockbase.shift);
 278         if (clocksource_register(&timer_device_clockbase)) {
 279                 printk(KERN_ERR "timer: clocksource failed to register\n");
 280                 return;
 281         }
 282
 283         /*
 284          * Always allocate a primary timer.
 285          */
 286         timer_device_alloc_event("timer-primary", -1, CPU_MASK_ALL_PTR);
 287
 288 #if defined(CONFIG_GENERIC_CLOCKEVENTS_BROADCAST)
 289         /*
 290          * If BROADCAST is selected we need to add a broadcast timer.
 291          */
 292         timer_device_alloc_event("timer-broadcast", -1, CPU_MASK_ALL_PTR);
 293 #endif
 294
 295         /*
 296          * Allocate extra timers that are requested.
 297          */
 298         for (i = 0; i < CONFIG_TIMER_EXTRA_ALLOC; i++) {
 299                 timer_device_alloc_event("timer-extra", -1, CPU_MASK_ALL_PTR);
 300         }
 301 }