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/platform_device.h>
  21 #include <linux/sched_clock.h>
  22
  23 #include <asm/mach/irq.h>
  24 #include <asm/mach/time.h>
  25
  26 #include <mach/cputype.h>
  27 #include <mach/hardware.h>
  28 #include <mach/time.h>
  29
  30 #include "clock.h"
  31
  32 static struct clock_event_device clockevent_davinci;
  33 static unsigned int davinci_clock_tick_rate;
  34
  35 /*
  36  * This driver configures the 2 64-bit count-up timers as 4 independent
  37  * 32-bit count-up timers used as follows:
  38  */
  39
  40 enum {
  41         TID_CLOCKEVENT,
  42         TID_CLOCKSOURCE,
  43 };
  44
  45 /* Timer register offsets */
  46 #define PID12                   0x0
  47 #define TIM12                   0x10
  48 #define TIM34                   0x14
  49 #define PRD12                   0x18
  50 #define PRD34                   0x1c
  51 #define TCR                     0x20
  52 #define TGCR                    0x24
  53 #define WDTCR                   0x28
  54
  55 /* Offsets of the 8 compare registers */
  56 #define CMP12_0                 0x60
  57 #define CMP12_1                 0x64
  58 #define CMP12_2                 0x68
  59 #define CMP12_3                 0x6c
  60 #define CMP12_4                 0x70
  61 #define CMP12_5                 0x74
  62 #define CMP12_6                 0x78
  63 #define CMP12_7                 0x7c
  64
  65 /* Timer register bitfields */
  66 #define TCR_ENAMODE_DISABLE          0x0
  67 #define TCR_ENAMODE_ONESHOT          0x1
  68 #define TCR_ENAMODE_PERIODIC         0x2
  69 #define TCR_ENAMODE_MASK             0x3
  70
  71 #define TGCR_TIMMODE_SHIFT           2
  72 #define TGCR_TIMMODE_64BIT_GP        0x0
  73 #define TGCR_TIMMODE_32BIT_UNCHAINED 0x1
  74 #define TGCR_TIMMODE_64BIT_WDOG      0x2
  75 #define TGCR_TIMMODE_32BIT_CHAINED   0x3
  76
  77 #define TGCR_TIM12RS_SHIFT           0
  78 #define TGCR_TIM34RS_SHIFT           1
  79 #define TGCR_RESET                   0x0
  80 #define TGCR_UNRESET                 0x1
  81 #define TGCR_RESET_MASK              0x3
  82
  83 #define WDTCR_WDEN_SHIFT             14
  84 #define WDTCR_WDEN_DISABLE           0x0
  85 #define WDTCR_WDEN_ENABLE            0x1
  86 #define WDTCR_WDKEY_SHIFT            16
  87 #define WDTCR_WDKEY_SEQ0             0xa5c6
  88 #define WDTCR_WDKEY_SEQ1             0xda7e
  89
  90 struct timer_s {
  91         char *name;
  92         unsigned int id;
  93         unsigned long period;
  94         unsigned long opts;
  95         unsigned long flags;
  96         void __iomem *base;
  97         unsigned long tim_off;
  98         unsigned long prd_off;
  99         unsigned long enamode_shift;
 100         struct irqaction irqaction;
 101 };
 102 static struct timer_s timers[];
 103
 104 /* values for 'opts' field of struct timer_s */
 105 #define TIMER_OPTS_DISABLED             0x01
 106 #define TIMER_OPTS_ONESHOT              0x02
 107 #define TIMER_OPTS_PERIODIC             0x04
 108 #define TIMER_OPTS_STATE_MASK           0x07
 109
 110 #define TIMER_OPTS_USE_COMPARE          0x80000000
 111 #define USING_COMPARE(t)                ((t)->opts & TIMER_OPTS_USE_COMPARE)
 112
 113 static char *id_to_name[] = {
 114         [T0_BOT]        = "timer0_0",
 115         [T0_TOP]        = "timer0_1",
 116         [T1_BOT]        = "timer1_0",
 117         [T1_TOP]        = "timer1_1",
 118 };
 119
 120 static int timer32_config(struct timer_s *t)
 121 {
 122         u32 tcr;
 123         struct davinci_soc_info *soc_info = &davinci_soc_info;
 124
 125         if (USING_COMPARE(t)) {
 126                 struct davinci_timer_instance *dtip =
 127                                 soc_info->timer_info->timers;
 128                 int event_timer = ID_TO_TIMER(timers[TID_CLOCKEVENT].id);
 129
 130                 /*
 131                  * Next interrupt should be the current time reg value plus
 132                  * the new period (using 32-bit unsigned addition/wrapping
 133                  * to 0 on overflow).  This assumes that the clocksource
 134                  * is setup to count to 2^32-1 before wrapping around to 0.
 135                  */
 136                 __raw_writel(__raw_readl(t->base + t->tim_off) + t->period,
 137                         t->base + dtip[event_timer].cmp_off);
 138         } else {
 139                 tcr = __raw_readl(t->base + TCR);
 140
 141                 /* disable timer */
 142                 tcr &= ~(TCR_ENAMODE_MASK << t->enamode_shift);
 143                 __raw_writel(tcr, t->base + TCR);
 144
 145                 /* reset counter to zero, set new period */
 146                 __raw_writel(0, t->base + t->tim_off);
 147                 __raw_writel(t->period, t->base + t->prd_off);
 148
 149                 /* Set enable mode */
 150                 if (t->opts & TIMER_OPTS_ONESHOT)
 151                         tcr |= TCR_ENAMODE_ONESHOT << t->enamode_shift;
 152                 else if (t->opts & TIMER_OPTS_PERIODIC)
 153                         tcr |= TCR_ENAMODE_PERIODIC << t->enamode_shift;
 154
 155                 __raw_writel(tcr, t->base + TCR);
 156         }
 157         return 0;
 158 }
 159
 160 static inline u32 timer32_read(struct timer_s *t)
 161 {
 162         return __raw_readl(t->base + t->tim_off);
 163 }
 164
 165 static irqreturn_t timer_interrupt(int irq, void *dev_id)
 166 {
 167         struct clock_event_device *evt = &clockevent_davinci;
 168
 169         evt->event_handler(evt);
 170         return IRQ_HANDLED;
 171 }
 172
 173 /* called when 32-bit counter wraps */
 174 static irqreturn_t freerun_interrupt(int irq, void *dev_id)
 175 {
 176         return IRQ_HANDLED;
 177 }
 178
 179 static struct timer_s timers[] = {
 180         [TID_CLOCKEVENT] = {
 181                 .name      = "clockevent",
 182                 .opts      = TIMER_OPTS_DISABLED,
 183                 .irqaction = {
 184                         .flags   = IRQF_TIMER,
 185                         .handler = timer_interrupt,
 186                 }
 187         },
 188         [TID_CLOCKSOURCE] = {
 189                 .name       = "free-run counter",
 190                 .period     = ~0,
 191                 .opts       = TIMER_OPTS_PERIODIC,
 192                 .irqaction = {
 193                         .flags   = IRQF_TIMER,
 194                         .handler = freerun_interrupt,
 195                 }
 196         },
 197 };
 198
 199 static void __init timer_init(void)
 200 {
 201         struct davinci_soc_info *soc_info = &davinci_soc_info;
 202         struct davinci_timer_instance *dtip = soc_info->timer_info->timers;
 203         void __iomem *base[2];
 204         int i;
 205
 206         /* Global init of each 64-bit timer as a whole */
 207         for(i=0; i<2; i++) {
 208                 u32 tgcr;
 209
 210                 base[i] = ioremap(dtip[i].base, SZ_4K);
 211                 if (WARN_ON(!base[i]))
 212                         continue;
 213
 214                 /* Disabled, Internal clock source */
 215                 __raw_writel(0, base[i] + TCR);
 216
 217                 /* reset both timers, no pre-scaler for timer34 */
 218                 tgcr = 0;
 219                 __raw_writel(tgcr, base[i] + TGCR);
 220
 221                 /* Set both timers to unchained 32-bit */
 222                 tgcr = TGCR_TIMMODE_32BIT_UNCHAINED << TGCR_TIMMODE_SHIFT;
 223                 __raw_writel(tgcr, base[i] + TGCR);
 224
 225                 /* Unreset timers */
 226                 tgcr |= (TGCR_UNRESET << TGCR_TIM12RS_SHIFT) |
 227                         (TGCR_UNRESET << TGCR_TIM34RS_SHIFT);
 228                 __raw_writel(tgcr, base[i] + TGCR);
 229
 230                 /* Init both counters to zero */
 231                 __raw_writel(0, base[i] + TIM12);
 232                 __raw_writel(0, base[i] + TIM34);
 233         }
 234
 235         /* Init of each timer as a 32-bit timer */
 236         for (i=0; i< ARRAY_SIZE(timers); i++) {
 237                 struct timer_s *t = &timers[i];
 238                 int timer = ID_TO_TIMER(t->id);
 239                 u32 irq;
 240
 241                 t->base = base[timer];
 242                 if (!t->base)
 243                         continue;
 244
 245                 if (IS_TIMER_BOT(t->id)) {
 246                         t->enamode_shift = 6;
 247                         t->tim_off = TIM12;
 248                         t->prd_off = PRD12;
 249                         irq = dtip[timer].bottom_irq;
 250                 } else {
 251                         t->enamode_shift = 22;
 252                         t->tim_off = TIM34;
 253                         t->prd_off = PRD34;
 254                         irq = dtip[timer].top_irq;
 255                 }
 256
 257                 /* Register interrupt */
 258                 t->irqaction.name = t->name;
 259                 t->irqaction.dev_id = (void *)t;
 260
 261                 if (t->irqaction.handler != NULL) {
 262                         irq = USING_COMPARE(t) ? dtip[i].cmp_irq : irq;
 263                         setup_irq(irq, &t->irqaction);
 264                 }
 265         }
 266 }
 267
 268 /*
 269  * clocksource
 270  */
 271 static cycle_t read_cycles(struct clocksource *cs)
 272 {
 273         struct timer_s *t = &timers[TID_CLOCKSOURCE];
 274
 275         return (cycles_t)timer32_read(t);
 276 }
 277
 278 static struct clocksource clocksource_davinci = {
 279         .rating         = 300,
 280         .read           = read_cycles,
 281         .mask           = CLOCKSOURCE_MASK(32),
 282         .flags          = CLOCK_SOURCE_IS_CONTINUOUS,
 283 };
 284
 285 /*
 286  * Overwrite weak default sched_clock with something more precise
 287  */
 288 static u64 notrace davinci_read_sched_clock(void)
 289 {
 290         return timer32_read(&timers[TID_CLOCKSOURCE]);
 291 }
 292
 293 /*
 294  * clockevent
 295  */
 296 static int davinci_set_next_event(unsigned long cycles,
 297                                   struct clock_event_device *evt)
 298 {
 299         struct timer_s *t = &timers[TID_CLOCKEVENT];
 300
 301         t->period = cycles;
 302         timer32_config(t);
 303         return 0;
 304 }
 305
 306 static void davinci_set_mode(enum clock_event_mode mode,
 307                              struct clock_event_device *evt)
 308 {
 309         struct timer_s *t = &timers[TID_CLOCKEVENT];
 310
 311         switch (mode) {
 312         case CLOCK_EVT_MODE_PERIODIC:
 313                 t->period = davinci_clock_tick_rate / (HZ);
 314                 t->opts &= ~TIMER_OPTS_STATE_MASK;
 315                 t->opts |= TIMER_OPTS_PERIODIC;
 316                 timer32_config(t);
 317                 break;
 318         case CLOCK_EVT_MODE_ONESHOT:
 319                 t->opts &= ~TIMER_OPTS_STATE_MASK;
 320                 t->opts |= TIMER_OPTS_ONESHOT;
 321                 break;
 322         case CLOCK_EVT_MODE_UNUSED:
 323         case CLOCK_EVT_MODE_SHUTDOWN:
 324                 t->opts &= ~TIMER_OPTS_STATE_MASK;
 325                 t->opts |= TIMER_OPTS_DISABLED;
 326                 break;
 327         case CLOCK_EVT_MODE_RESUME:
 328                 break;
 329         }
 330 }
 331
 332 static struct clock_event_device clockevent_davinci = {
 333         .features       = CLOCK_EVT_FEAT_PERIODIC | CLOCK_EVT_FEAT_ONESHOT,
 334         .set_next_event = davinci_set_next_event,
 335         .set_mode       = davinci_set_mode,
 336 };
 337
 338
 339 void __init davinci_timer_init(void)
 340 {
 341         struct clk *timer_clk;
 342         struct davinci_soc_info *soc_info = &davinci_soc_info;
 343         unsigned int clockevent_id;
 344         unsigned int clocksource_id;
 345         int i;
 346
 347         clockevent_id = soc_info->timer_info->clockevent_id;
 348         clocksource_id = soc_info->timer_info->clocksource_id;
 349
 350         timers[TID_CLOCKEVENT].id = clockevent_id;
 351         timers[TID_CLOCKSOURCE].id = clocksource_id;
 352
 353         /*
 354          * If using same timer for both clock events & clocksource,
 355          * a compare register must be used to generate an event interrupt.
 356          * This is equivalent to a oneshot timer only (not periodic).
 357          */
 358         if (clockevent_id == clocksource_id) {
 359                 struct davinci_timer_instance *dtip =
 360                                 soc_info->timer_info->timers;
 361                 int event_timer = ID_TO_TIMER(clockevent_id);
 362
 363                 /* Only bottom timers can use compare regs */
 364                 if (IS_TIMER_TOP(clockevent_id))
 365                         pr_warn("%s: Invalid use of system timers.  Results unpredictable.\n",
 366                                 __func__);
 367                 else if ((dtip[event_timer].cmp_off == 0)
 368                                 || (dtip[event_timer].cmp_irq == 0))
 369                         pr_warn("%s: Invalid timer instance setup.  Results unpredictable.\n",
 370                                 __func__);
 371                 else {
 372                         timers[TID_CLOCKEVENT].opts |= TIMER_OPTS_USE_COMPARE;
 373                         clockevent_davinci.features = CLOCK_EVT_FEAT_ONESHOT;
 374                 }
 375         }
 376
 377         timer_clk = clk_get(NULL, "timer0");
 378         BUG_ON(IS_ERR(timer_clk));
 379         clk_prepare_enable(timer_clk);
 380
 381         /* init timer hw */
 382         timer_init();
 383
 384         davinci_clock_tick_rate = clk_get_rate(timer_clk);
 385
 386         /* setup clocksource */
 387         clocksource_davinci.name = id_to_name[clocksource_id];
 388         if (clocksource_register_hz(&clocksource_davinci,
 389                                     davinci_clock_tick_rate))
 390                 pr_err("%s: can't register clocksource!\n",
 391                        clocksource_davinci.name);
 392
 393         sched_clock_register(davinci_read_sched_clock, 32,
 394                           davinci_clock_tick_rate);
 395
 396         /* setup clockevent */
 397         clockevent_davinci.name = id_to_name[timers[TID_CLOCKEVENT].id];
 398
 399         clockevent_davinci.cpumask = cpumask_of(0);
 400         clockevents_config_and_register(&clockevent_davinci,
 401                                         davinci_clock_tick_rate, 1, 0xfffffffe);
 402
 403         for (i=0; i< ARRAY_SIZE(timers); i++)
 404                 timer32_config(&timers[i]);
 405 }
 406
 407 /* reset board using watchdog timer */
 408 void davinci_watchdog_reset(struct platform_device *pdev)
 409 {
 410         u32 tgcr, wdtcr;
 411         void __iomem *base;
 412         struct clk *wd_clk;
 413
 414         base = ioremap(pdev->resource[0].start, SZ_4K);
 415         if (WARN_ON(!base))
 416                 return;
 417
 418         wd_clk = clk_get(&pdev->dev, NULL);
 419         if (WARN_ON(IS_ERR(wd_clk)))
 420                 return;
 421         clk_prepare_enable(wd_clk);
 422
 423         /* disable, internal clock source */
 424         __raw_writel(0, base + TCR);
 425
 426         /* reset timer, set mode to 64-bit watchdog, and unreset */
 427         tgcr = 0;
 428         __raw_writel(tgcr, base + TGCR);
 429         tgcr = TGCR_TIMMODE_64BIT_WDOG << TGCR_TIMMODE_SHIFT;
 430         tgcr |= (TGCR_UNRESET << TGCR_TIM12RS_SHIFT) |
 431                 (TGCR_UNRESET << TGCR_TIM34RS_SHIFT);
 432         __raw_writel(tgcr, base + TGCR);
 433
 434         /* clear counter and period regs */
 435         __raw_writel(0, base + TIM12);
 436         __raw_writel(0, base + TIM34);
 437         __raw_writel(0, base + PRD12);
 438         __raw_writel(0, base + PRD34);
 439
 440         /* put watchdog in pre-active state */
 441         wdtcr = __raw_readl(base + WDTCR);
 442         wdtcr = (WDTCR_WDKEY_SEQ0 << WDTCR_WDKEY_SHIFT) |
 443                 (WDTCR_WDEN_ENABLE << WDTCR_WDEN_SHIFT);
 444         __raw_writel(wdtcr, base + WDTCR);
 445
 446         /* put watchdog in active state */
 447         wdtcr = (WDTCR_WDKEY_SEQ1 << WDTCR_WDKEY_SHIFT) |
 448                 (WDTCR_WDEN_ENABLE << WDTCR_WDEN_SHIFT);
 449         __raw_writel(wdtcr, base + WDTCR);
 450
 451         /* write an invalid value to the WDKEY field to trigger
 452          * a watchdog reset */
 453         wdtcr = 0x00004000;
 454         __raw_writel(wdtcr, base + WDTCR);
 455 }