arch/arm/mach-davinci/time.c

   1 /*
   2  * DaVinci timer subsystem
   3  *
   4  * Author: Kevin Hilman, MontaVista Software, Inc. <source@mvista.com>
   5  *
   6  * 2007 (c) MontaVista Software, Inc. This file is licensed under
   7  * the terms of the GNU General Public License version 2. This program
   8  * is licensed "as is" without any warranty of any kind, whether express
   9  * or implied.
  10  */
  11 #include <linux/kernel.h>
  12 #include <linux/init.h>
  13 #include <linux/types.h>
  14 #include <linux/interrupt.h>
  15 #include <linux/clocksource.h>
  16 #include <linux/clockchips.h>
  17 #include <linux/io.h>
  18 #include <linux/clk.h>
  19 #include <linux/err.h>
  20 #include <linux/of.h>
  21 #include <linux/platform_device.h>
  22 #include <linux/sched_clock.h>
  23
  24 #include <asm/mach/irq.h>
  25 #include <asm/mach/time.h>
  26
  27 #include <mach/cputype.h>
  28 #include <mach/hardware.h>
  29 #include <mach/time.h>
  30
  31 static struct clock_event_device clockevent_davinci;
  32 static unsigned int davinci_clock_tick_rate;
  33
  34 /*
  35  * This driver configures the 2 64-bit count-up timers as 4 independent
  36  * 32-bit count-up timers used as follows:
  37  */
  38
  39 enum {
  40         TID_CLOCKEVENT,
  41         TID_CLOCKSOURCE,
  42 };
  43
  44 /* Timer register offsets */
  45 #define PID12                   0x0
  46 #define TIM12                   0x10
  47 #define TIM34                   0x14
  48 #define PRD12                   0x18
  49 #define PRD34                   0x1c
  50 #define TCR                     0x20
  51 #define TGCR                    0x24
  52 #define WDTCR                   0x28
  53
  54 /* Offsets of the 8 compare registers */
  55 #define CMP12_0                 0x60
  56 #define CMP12_1                 0x64
  57 #define CMP12_2                 0x68
  58 #define CMP12_3                 0x6c
  59 #define CMP12_4                 0x70
  60 #define CMP12_5                 0x74
  61 #define CMP12_6                 0x78
  62 #define CMP12_7                 0x7c
  63
  64 /* Timer register bitfields */
  65 #define TCR_ENAMODE_DISABLE          0x0
  66 #define TCR_ENAMODE_ONESHOT          0x1
  67 #define TCR_ENAMODE_PERIODIC         0x2
  68 #define TCR_ENAMODE_MASK             0x3
  69
  70 #define TGCR_TIMMODE_SHIFT           2
  71 #define TGCR_TIMMODE_64BIT_GP        0x0
  72 #define TGCR_TIMMODE_32BIT_UNCHAINED 0x1
  73 #define TGCR_TIMMODE_64BIT_WDOG      0x2
  74 #define TGCR_TIMMODE_32BIT_CHAINED   0x3
  75
  76 #define TGCR_TIM12RS_SHIFT           0
  77 #define TGCR_TIM34RS_SHIFT           1
  78 #define TGCR_RESET                   0x0
  79 #define TGCR_UNRESET                 0x1
  80 #define TGCR_RESET_MASK              0x3
  81
  82 struct timer_s {
  83         char *name;
  84         unsigned int id;
  85         unsigned long period;
  86         unsigned long opts;
  87         unsigned long flags;
  88         void __iomem *base;
  89         unsigned long tim_off;
  90         unsigned long prd_off;
  91         unsigned long enamode_shift;
  92         struct irqaction irqaction;
  93 };
  94 static struct timer_s timers[];
  95
  96 /* values for 'opts' field of struct timer_s */
  97 #define TIMER_OPTS_DISABLED             0x01
  98 #define TIMER_OPTS_ONESHOT              0x02
  99 #define TIMER_OPTS_PERIODIC             0x04
 100 #define TIMER_OPTS_STATE_MASK           0x07
 101
 102 #define TIMER_OPTS_USE_COMPARE          0x80000000
 103 #define USING_COMPARE(t)                ((t)->opts & TIMER_OPTS_USE_COMPARE)
 104
 105 static char *id_to_name[] = {
 106         [T0_BOT]        = "timer0_0",
 107         [T0_TOP]        = "timer0_1",
 108         [T1_BOT]        = "timer1_0",
 109         [T1_TOP]        = "timer1_1",
 110 };
 111
 112 static int timer32_config(struct timer_s *t)
 113 {
 114         u32 tcr;
 115         struct davinci_soc_info *soc_info = &davinci_soc_info;
 116
 117         if (USING_COMPARE(t)) {
 118                 struct davinci_timer_instance *dtip =
 119                                 soc_info->timer_info->timers;
 120                 int event_timer = ID_TO_TIMER(timers[TID_CLOCKEVENT].id);
 121
 122                 /*
 123                  * Next interrupt should be the current time reg value plus
 124                  * the new period (using 32-bit unsigned addition/wrapping
 125                  * to 0 on overflow).  This assumes that the clocksource
 126                  * is setup to count to 2^32-1 before wrapping around to 0.
 127                  */
 128                 __raw_writel(__raw_readl(t->base + t->tim_off) + t->period,
 129                         t->base + dtip[event_timer].cmp_off);
 130         } else {
 131                 tcr = __raw_readl(t->base + TCR);
 132
 133                 /* disable timer */
 134                 tcr &= ~(TCR_ENAMODE_MASK << t->enamode_shift);
 135                 __raw_writel(tcr, t->base + TCR);
 136
 137                 /* reset counter to zero, set new period */
 138                 __raw_writel(0, t->base + t->tim_off);
 139                 __raw_writel(t->period, t->base + t->prd_off);
 140
 141                 /* Set enable mode */
 142                 if (t->opts & TIMER_OPTS_ONESHOT)
 143                         tcr |= TCR_ENAMODE_ONESHOT << t->enamode_shift;
 144                 else if (t->opts & TIMER_OPTS_PERIODIC)
 145                         tcr |= TCR_ENAMODE_PERIODIC << t->enamode_shift;
 146
 147                 __raw_writel(tcr, t->base + TCR);
 148         }
 149         return 0;
 150 }
 151
 152 static inline u32 timer32_read(struct timer_s *t)
 153 {
 154         return __raw_readl(t->base + t->tim_off);
 155 }
 156
 157 static irqreturn_t timer_interrupt(int irq, void *dev_id)
 158 {
 159         struct clock_event_device *evt = &clockevent_davinci;
 160
 161         evt->event_handler(evt);
 162         return IRQ_HANDLED;
 163 }
 164
 165 /* called when 32-bit counter wraps */
 166 static irqreturn_t freerun_interrupt(int irq, void *dev_id)
 167 {
 168         return IRQ_HANDLED;
 169 }
 170
 171 static struct timer_s timers[] = {
 172         [TID_CLOCKEVENT] = {
 173                 .name      = "clockevent",
 174                 .opts      = TIMER_OPTS_DISABLED,
 175                 .irqaction = {
 176                         .flags   = IRQF_TIMER,
 177                         .handler = timer_interrupt,
 178                 }
 179         },
 180         [TID_CLOCKSOURCE] = {
 181                 .name       = "free-run counter",
 182                 .period     = ~0,
 183                 .opts       = TIMER_OPTS_PERIODIC,
 184                 .irqaction = {
 185                         .flags   = IRQF_TIMER,
 186                         .handler = freerun_interrupt,
 187                 }
 188         },
 189 };
 190
 191 static void __init timer_init(void)
 192 {
 193         struct davinci_soc_info *soc_info = &davinci_soc_info;
 194         struct davinci_timer_instance *dtip = soc_info->timer_info->timers;
 195         void __iomem *base[2];
 196         int i;
 197
 198         /* Global init of each 64-bit timer as a whole */
 199         for(i=0; i<2; i++) {
 200                 u32 tgcr;
 201
 202                 base[i] = ioremap(dtip[i].base, SZ_4K);
 203                 if (WARN_ON(!base[i]))
 204                         continue;
 205
 206                 /* Disabled, Internal clock source */
 207                 __raw_writel(0, base[i] + TCR);
 208
 209                 /* reset both timers, no pre-scaler for timer34 */
 210                 tgcr = 0;
 211                 __raw_writel(tgcr, base[i] + TGCR);
 212
 213                 /* Set both timers to unchained 32-bit */
 214                 tgcr = TGCR_TIMMODE_32BIT_UNCHAINED << TGCR_TIMMODE_SHIFT;
 215                 __raw_writel(tgcr, base[i] + TGCR);
 216
 217                 /* Unreset timers */
 218                 tgcr |= (TGCR_UNRESET << TGCR_TIM12RS_SHIFT) |
 219                         (TGCR_UNRESET << TGCR_TIM34RS_SHIFT);
 220                 __raw_writel(tgcr, base[i] + TGCR);
 221
 222                 /* Init both counters to zero */
 223                 __raw_writel(0, base[i] + TIM12);
 224                 __raw_writel(0, base[i] + TIM34);
 225         }
 226
 227         /* Init of each timer as a 32-bit timer */
 228         for (i=0; i< ARRAY_SIZE(timers); i++) {
 229                 struct timer_s *t = &timers[i];
 230                 int timer = ID_TO_TIMER(t->id);
 231                 u32 irq;
 232
 233                 t->base = base[timer];
 234                 if (!t->base)
 235                         continue;
 236
 237                 if (IS_TIMER_BOT(t->id)) {
 238                         t->enamode_shift = 6;
 239                         t->tim_off = TIM12;
 240                         t->prd_off = PRD12;
 241                         irq = dtip[timer].bottom_irq;
 242                 } else {
 243                         t->enamode_shift = 22;
 244                         t->tim_off = TIM34;
 245                         t->prd_off = PRD34;
 246                         irq = dtip[timer].top_irq;
 247                 }
 248
 249                 /* Register interrupt */
 250                 t->irqaction.name = t->name;
 251                 t->irqaction.dev_id = (void *)t;
 252
 253                 if (t->irqaction.handler != NULL) {
 254                         irq = USING_COMPARE(t) ? dtip[i].cmp_irq : irq;
 255                         setup_irq(irq, &t->irqaction);
 256                 }
 257         }
 258 }
 259
 260 /*
 261  * clocksource
 262  */
 263 static u64 read_cycles(struct clocksource *cs)
 264 {
 265         struct timer_s *t = &timers[TID_CLOCKSOURCE];
 266
 267         return (cycles_t)timer32_read(t);
 268 }
 269
 270 static struct clocksource clocksource_davinci = {
 271         .rating         = 300,
 272         .read           = read_cycles,
 273         .mask           = CLOCKSOURCE_MASK(32),
 274         .flags          = CLOCK_SOURCE_IS_CONTINUOUS,
 275 };
 276
 277 /*
 278  * Overwrite weak default sched_clock with something more precise
 279  */
 280 static u64 notrace davinci_read_sched_clock(void)
 281 {
 282         return timer32_read(&timers[TID_CLOCKSOURCE]);
 283 }
 284
 285 /*
 286  * clockevent
 287  */
 288 static int davinci_set_next_event(unsigned long cycles,
 289                                   struct clock_event_device *evt)
 290 {
 291         struct timer_s *t = &timers[TID_CLOCKEVENT];
 292
 293         t->period = cycles;
 294         timer32_config(t);
 295         return 0;
 296 }
 297
 298 static int davinci_shutdown(struct clock_event_device *evt)
 299 {
 300         struct timer_s *t = &timers[TID_CLOCKEVENT];
 301
 302         t->opts &= ~TIMER_OPTS_STATE_MASK;
 303         t->opts |= TIMER_OPTS_DISABLED;
 304         return 0;
 305 }
 306
 307 static int davinci_set_oneshot(struct clock_event_device *evt)
 308 {
 309         struct timer_s *t = &timers[TID_CLOCKEVENT];
 310
 311         t->opts &= ~TIMER_OPTS_STATE_MASK;
 312         t->opts |= TIMER_OPTS_ONESHOT;
 313         return 0;
 314 }
 315
 316 static int davinci_set_periodic(struct clock_event_device *evt)
 317 {
 318         struct timer_s *t = &timers[TID_CLOCKEVENT];
 319
 320         t->period = davinci_clock_tick_rate / (HZ);
 321         t->opts &= ~TIMER_OPTS_STATE_MASK;
 322         t->opts |= TIMER_OPTS_PERIODIC;
 323         timer32_config(t);
 324         return 0;
 325 }
 326
 327 static struct clock_event_device clockevent_davinci = {
 328         .features               = CLOCK_EVT_FEAT_PERIODIC |
 329                                   CLOCK_EVT_FEAT_ONESHOT,
 330         .set_next_event         = davinci_set_next_event,
 331         .set_state_shutdown     = davinci_shutdown,
 332         .set_state_periodic     = davinci_set_periodic,
 333         .set_state_oneshot      = davinci_set_oneshot,
 334 };
 335
 336 void __init davinci_timer_init(struct clk *timer_clk)
 337 {
 338         struct davinci_soc_info *soc_info = &davinci_soc_info;
 339         unsigned int clockevent_id;
 340         unsigned int clocksource_id;
 341         int i;
 342
 343         clockevent_id = soc_info->timer_info->clockevent_id;
 344         clocksource_id = soc_info->timer_info->clocksource_id;
 345
 346         timers[TID_CLOCKEVENT].id = clockevent_id;
 347         timers[TID_CLOCKSOURCE].id = clocksource_id;
 348
 349         /*
 350          * If using same timer for both clock events & clocksource,
 351          * a compare register must be used to generate an event interrupt.
 352          * This is equivalent to a oneshot timer only (not periodic).
 353          */
 354         if (clockevent_id == clocksource_id) {
 355                 struct davinci_timer_instance *dtip =
 356                                 soc_info->timer_info->timers;
 357                 int event_timer = ID_TO_TIMER(clockevent_id);
 358
 359                 /* Only bottom timers can use compare regs */
 360                 if (IS_TIMER_TOP(clockevent_id))
 361                         pr_warn("%s: Invalid use of system timers.  Results unpredictable.\n",
 362                                 __func__);
 363                 else if ((dtip[event_timer].cmp_off == 0)
 364                                 || (dtip[event_timer].cmp_irq == 0))
 365                         pr_warn("%s: Invalid timer instance setup.  Results unpredictable.\n",
 366                                 __func__);
 367                 else {
 368                         timers[TID_CLOCKEVENT].opts |= TIMER_OPTS_USE_COMPARE;
 369                         clockevent_davinci.features = CLOCK_EVT_FEAT_ONESHOT;
 370                 }
 371         }
 372
 373         BUG_ON(IS_ERR(timer_clk));
 374         clk_prepare_enable(timer_clk);
 375
 376         /* init timer hw */
 377         timer_init();
 378
 379         davinci_clock_tick_rate = clk_get_rate(timer_clk);
 380
 381         /* setup clocksource */
 382         clocksource_davinci.name = id_to_name[clocksource_id];
 383         if (clocksource_register_hz(&clocksource_davinci,
 384                                     davinci_clock_tick_rate))
 385                 pr_err("%s: can't register clocksource!\n",
 386                        clocksource_davinci.name);
 387
 388         sched_clock_register(davinci_read_sched_clock, 32,
 389                           davinci_clock_tick_rate);
 390
 391         /* setup clockevent */
 392         clockevent_davinci.name = id_to_name[timers[TID_CLOCKEVENT].id];
 393
 394         clockevent_davinci.cpumask = cpumask_of(0);
 395         clockevents_config_and_register(&clockevent_davinci,
 396                                         davinci_clock_tick_rate, 1, 0xfffffffe);
 397
 398         for (i=0; i< ARRAY_SIZE(timers); i++)
 399                 timer32_config(&timers[i]);
 400 }