target/linux/s3c24xx/patches-2.6.30/070-s3c24xx-time.patch

   1 --- /dev/null
   2 +++ b/arch/arm/plat-s3c24xx/time.c
   3 @@ -0,0 +1,480 @@
   4 +/* linux/arch/arm/plat-s3c24xx/time.c
   5 + *
   6 + * Copyright (C) 2003-2005 Simtec Electronics
   7 + *     Ben Dooks, <ben@simtec.co.uk>
   8 + *
   9 + * dyn_tick support by Andrzej Zaborowski based on omap_dyn_tick_timer.
  10 + *
  11 + * This program is free software; you can redistribute it and/or modify
  12 + * it under the terms of the GNU General Public License as published by
  13 + * the Free Software Foundation; either version 2 of the License, or
  14 + * (at your option) any later version.
  15 + *
  16 + * This program is distributed in the hope that it will be useful,
  17 + * but WITHOUT ANY WARRANTY; without even the implied warranty of
  18 + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  19 + * GNU General Public License for more details.
  20 + *
  21 + * You should have received a copy of the GNU General Public License
  22 + * along with this program; if not, write to the Free Software
  23 + * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
  24 + */
  25 +
  26 +#include <linux/kernel.h>
  27 +#include <linux/sched.h>
  28 +#include <linux/init.h>
  29 +#include <linux/interrupt.h>
  30 +#include <linux/irq.h>
  31 +#include <linux/err.h>
  32 +#include <linux/clk.h>
  33 +
  34 +#include <asm/system.h>
  35 +#include <asm/leds.h>
  36 +#include <asm/mach-types.h>
  37 +
  38 +#include <asm/io.h>
  39 +#include <asm/irq.h>
  40 +#include <mach/map.h>
  41 +#include <asm/plat-s3c/regs-timer.h>
  42 +#include <mach/regs-irq.h>
  43 +#include <asm/mach/time.h>
  44 +
  45 +#include <asm/plat-s3c24xx/clock.h>
  46 +#include <asm/plat-s3c24xx/cpu.h>
  47 +
  48 +static unsigned long timer_startval;
  49 +static unsigned long timer_usec_ticks;
  50 +static struct work_struct resume_work;
  51 +
  52 +unsigned long pclk;
  53 +struct clk *clk;
  54 +
  55 +#define TIMER_USEC_SHIFT 16
  56 +
  57 +/* we use the shifted arithmetic to work out the ratio of timer ticks
  58 + * to usecs, as often the peripheral clock is not a nice even multiple
  59 + * of 1MHz.
  60 + *
  61 + * shift of 14 and 15 are too low for the 12MHz, 16 seems to be ok
  62 + * for the current HZ value of 200 without producing overflows.
  63 + *
  64 + * Original patch by Dimitry Andric, updated by Ben Dooks
  65 +*/
  66 +
  67 +
  68 +/* timer_mask_usec_ticks
  69 + *
  70 + * given a clock and divisor, make the value to pass into timer_ticks_to_usec
  71 + * to scale the ticks into usecs
  72 +*/
  73 +
  74 +static inline unsigned long
  75 +timer_mask_usec_ticks(unsigned long scaler, unsigned long pclk)
  76 +{
  77 +       unsigned long den = pclk / 1000;
  78 +
  79 +       return ((1000 << TIMER_USEC_SHIFT) * scaler + (den >> 1)) / den;
  80 +}
  81 +
  82 +/* timer_ticks_to_usec
  83 + *
  84 + * convert timer ticks to usec.
  85 +*/
  86 +
  87 +static inline unsigned long timer_ticks_to_usec(unsigned long ticks)
  88 +{
  89 +       unsigned long res;
  90 +
  91 +       res = ticks * timer_usec_ticks;
  92 +       res += 1 << (TIMER_USEC_SHIFT - 4);     /* round up slightly */
  93 +
  94 +       return res >> TIMER_USEC_SHIFT;
  95 +}
  96 +
  97 +/***
  98 + * Returns microsecond  since last clock interrupt.  Note that interrupts
  99 + * will have been disabled by do_gettimeoffset()
 100 + * IRQs are disabled before entering here from do_gettimeofday()
 101 + */
 102 +
 103 +#define SRCPND_TIMER4 (1<<(IRQ_TIMER4 - IRQ_EINT0))
 104 +
 105 +unsigned long s3c2410_gettimeoffset (void)
 106 +{
 107 +       unsigned long tdone;
 108 +       unsigned long irqpend;
 109 +       unsigned long tval;
 110 +
 111 +       /* work out how many ticks have gone since last timer interrupt */
 112 +
 113 +        tval =  __raw_readl(S3C2410_TCNTO(4));
 114 +       tdone = timer_startval - tval;
 115 +
 116 +       /* check to see if there is an interrupt pending */
 117 +
 118 +       irqpend = __raw_readl(S3C2410_SRCPND);
 119 +       if (irqpend & SRCPND_TIMER4) {
 120 +               /* re-read the timer, and try and fix up for the missed
 121 +                * interrupt. Note, the interrupt may go off before the
 122 +                * timer has re-loaded from wrapping.
 123 +                */
 124 +
 125 +               tval =  __raw_readl(S3C2410_TCNTO(4));
 126 +               tdone = timer_startval - tval;
 127 +
 128 +               if (tval != 0)
 129 +                       tdone += timer_startval;
 130 +       }
 131 +
 132 +       return timer_ticks_to_usec(tdone);
 133 +}
 134 +
 135 +
 136 +/*
 137 + * IRQ handler for the timer
 138 + */
 139 +static irqreturn_t
 140 +s3c2410_timer_interrupt(int irq, void *dev_id)
 141 +{
 142 +       timer_tick();
 143 +       return IRQ_HANDLED;
 144 +}
 145 +
 146 +static struct irqaction s3c2410_timer_irq = {
 147 +       .name           = "S3C2410 Timer Tick",
 148 +       .flags          = IRQF_DISABLED | IRQF_TIMER | IRQF_IRQPOLL,
 149 +       .handler        = s3c2410_timer_interrupt,
 150 +};
 151 +
 152 +#define use_tclk1_12() ( \
 153 +       machine_is_bast()       || \
 154 +       machine_is_vr1000()     || \
 155 +       machine_is_anubis()     || \
 156 +       machine_is_osiris() )
 157 +
 158 +/*
 159 + * Set up timer interrupt, and return the current time in seconds.
 160 + *
 161 + * Currently we only use timer4, as it is the only timer which has no
 162 + * other function that can be exploited externally
 163 + */
 164 +static void s3c2410_timer_setup (void)
 165 +{
 166 +       unsigned long tcon;
 167 +       unsigned long tcnt;
 168 +       unsigned long tcfg1;
 169 +       unsigned long tcfg0;
 170 +
 171 +       tcnt = 0xffff;  /* default value for tcnt */
 172 +
 173 +       /* read the current timer configuration bits */
 174 +
 175 +       tcon = __raw_readl(S3C2410_TCON);
 176 +       tcfg1 = __raw_readl(S3C2410_TCFG1);
 177 +       tcfg0 = __raw_readl(S3C2410_TCFG0);
 178 +
 179 +       /* configure the system for whichever machine is in use */
 180 +
 181 +       if (use_tclk1_12()) {
 182 +               /* timer is at 12MHz, scaler is 1 */
 183 +               timer_usec_ticks = timer_mask_usec_ticks(1, 12000000);
 184 +               tcnt = 12000000 / HZ;
 185 +
 186 +               tcfg1 &= ~S3C2410_TCFG1_MUX4_MASK;
 187 +               tcfg1 |= S3C2410_TCFG1_MUX4_TCLK1;
 188 +       } else {
 189 +               /* since values around 50 to
 190 +                * 70MHz are not values we can directly generate the timer
 191 +                * value from, we need to pre-scale and divide before using it.
 192 +                *
 193 +                * for instance, using 50.7MHz and dividing by 6 gives 8.45MHz
 194 +                * (8.45 ticks per usec)
 195 +                */
 196 +
 197 +               /* configure clock tick */
 198 +               timer_usec_ticks = timer_mask_usec_ticks(6, pclk);
 199 +               printk("timer_usec_ticks = %lu\n", timer_usec_ticks);
 200 +
 201 +               tcfg1 &= ~S3C2410_TCFG1_MUX4_MASK;
 202 +               tcfg1 |= S3C2410_TCFG1_MUX4_DIV2;
 203 +
 204 +               tcfg0 &= ~S3C2410_TCFG_PRESCALER1_MASK;
 205 +               tcfg0 |= ((6 - 1) / 2) << S3C2410_TCFG_PRESCALER1_SHIFT;
 206 +
 207 +               tcnt = (pclk / 6) / HZ;
 208 +       }
 209 +
 210 +       /* timers reload after counting zero, so reduce the count by 1 */
 211 +
 212 +       tcnt--;
 213 +
 214 +       printk("timer tcon=%08lx, tcnt %04lx, tcfg %08lx,%08lx, usec %08lx\n",
 215 +              tcon, tcnt, tcfg0, tcfg1, timer_usec_ticks);
 216 +
 217 +       /* check to see if timer is within 16bit range... */
 218 +       if (tcnt > 0xffff) {
 219 +               panic("setup_timer: HZ is too small, cannot configure timer!");
 220 +               return;
 221 +       }
 222 +
 223 +       __raw_writel(tcfg1, S3C2410_TCFG1);
 224 +       __raw_writel(tcfg0, S3C2410_TCFG0);
 225 +
 226 +       timer_startval = tcnt;
 227 +       __raw_writel(tcnt, S3C2410_TCNTB(4));
 228 +
 229 +       /* ensure timer is stopped... */
 230 +
 231 +       tcon &= ~(7<<20);
 232 +       tcon |= S3C2410_TCON_T4RELOAD;
 233 +       tcon |= S3C2410_TCON_T4MANUALUPD;
 234 +
 235 +       __raw_writel(tcon, S3C2410_TCON);
 236 +       __raw_writel(tcnt, S3C2410_TCNTB(4));
 237 +       __raw_writel(tcnt, S3C2410_TCMPB(4));
 238 +
 239 +       /* start the timer running */
 240 +       tcon |= S3C2410_TCON_T4START;
 241 +       tcon &= ~S3C2410_TCON_T4MANUALUPD;
 242 +       __raw_writel(tcon, S3C2410_TCON);
 243 +
 244 +       __raw_writel(__raw_readl(S3C2410_INTMSK) & (~(1UL << 14)),
 245 +                    S3C2410_INTMSK);
 246 +
 247 +}
 248 +
 249 +struct sys_timer s3c24xx_timer;
 250 +static void timer_resume_work(struct work_struct *work)
 251 +{
 252 +       clk_enable(clk);
 253 +
 254 +#ifdef CONFIG_NO_IDLE_HZ
 255 +       if (s3c24xx_timer.dyn_tick->state & DYN_TICK_ENABLED)
 256 +               s3c24xx_timer.dyn_tick->enable();
 257 +       else
 258 +#endif
 259 +               s3c2410_timer_setup();
 260 +}
 261 +
 262 +static void __init s3c2410_timer_init (void)
 263 +{
 264 +       if (!use_tclk1_12()) {
 265 +               /* for the h1940 (and others), we use the pclk from the core
 266 +                * to generate the timer values.
 267 +                */
 268 +
 269 +               /* this is used as default if no other timer can be found */
 270 +               clk = clk_get(NULL, "timers");
 271 +               if (IS_ERR(clk))
 272 +                       panic("failed to get clock for system timer");
 273 +
 274 +               clk_enable(clk);
 275 +
 276 +               pclk = clk_get_rate(clk);
 277 +               printk("pclk = %lu\n", pclk);
 278 +       }
 279 +
 280 +       INIT_WORK(&resume_work, timer_resume_work);
 281 +       s3c2410_timer_setup();
 282 +       setup_irq(IRQ_TIMER4, &s3c2410_timer_irq);
 283 +}
 284 +
 285 +static void s3c2410_timer_resume_work(struct work_struct *work)
 286 +{
 287 +       s3c2410_timer_setup();
 288 +}
 289 +
 290 +static void s3c2410_timer_resume(void)
 291 +{
 292 +       static DECLARE_WORK(work, s3c2410_timer_resume_work);
 293 +       int res;
 294 +
 295 +       res = schedule_work(&work);
 296 +       if (!res)
 297 +               printk(KERN_ERR
 298 +                   "s3c2410_timer_resume_work already queued ???\n");
 299 +}
 300 +
 301 +#ifdef CONFIG_NO_IDLE_HZ
 302 +/*
 303 + * We'll set a constant prescaler so we don't have to bother setting it
 304 + * when reprogramming and so that we avoid costly divisions.
 305 + *
 306 + * (2 * HZ) << INPUT_FREQ_SHIFT is the desired frequency after prescaler.
 307 + * At HZ == 200, HZ * 1024 should work for PCLKs of up to ~53.5 MHz.
 308 + */
 309 +#define INPUT_FREQ_SHIFT       9
 310 +
 311 +static int ticks_last;
 312 +static int ticks_left;
 313 +static uint32_t tcnto_last;
 314 +
 315 +static inline int s3c24xx_timer_read(void)
 316 +{
 317 +       uint32_t tcnto = __raw_readl(S3C2410_TCNTO(4));
 318 +
 319 +       /*
 320 +        * WARNING: sometimes we get called before TCNTB has been
 321 +        * loaded into the counter and TCNTO then returns its previous
 322 +        * value and kill us, so don't do anything before counter is
 323 +        * reloaded.
 324 +        */
 325 +       if (unlikely(tcnto == tcnto_last))
 326 +               return ticks_last;
 327 +
 328 +       tcnto_last = -1;
 329 +       return tcnto <<
 330 +               ((__raw_readl(S3C2410_TCFG1) >> S3C2410_TCFG1_MUX4_SHIFT) & 3);
 331 +}
 332 +
 333 +static inline void s3c24xx_timer_program(int ticks)
 334 +{
 335 +       uint32_t tcon = __raw_readl(S3C2410_TCON) & ~(7 << 20);
 336 +       uint32_t tcfg1 = __raw_readl(S3C2410_TCFG1) & ~S3C2410_TCFG1_MUX4_MASK;
 337 +
 338 +       /* Just make sure the timer is stopped.  */
 339 +       __raw_writel(tcon, S3C2410_TCON);
 340 +
 341 +       /* TODO: add likely()ies / unlikely()ies */
 342 +       if (ticks >> 18) {
 343 +               ticks_last = min(ticks, 0xffff << 3);
 344 +               ticks_left = ticks - ticks_last;
 345 +               __raw_writel(tcfg1 | S3C2410_TCFG1_MUX4_DIV16, S3C2410_TCFG1);
 346 +               __raw_writel(ticks_last >> 3, S3C2410_TCNTB(4));
 347 +       } else if (ticks >> 17) {
 348 +               ticks_last = ticks;
 349 +               ticks_left = 0;
 350 +               __raw_writel(tcfg1 | S3C2410_TCFG1_MUX4_DIV8, S3C2410_TCFG1);
 351 +               __raw_writel(ticks_last >> 2, S3C2410_TCNTB(4));
 352 +       } else if (ticks >> 16) {
 353 +               ticks_last = ticks;
 354 +               ticks_left = 0;
 355 +               __raw_writel(tcfg1 | S3C2410_TCFG1_MUX4_DIV4, S3C2410_TCFG1);
 356 +               __raw_writel(ticks_last >> 1, S3C2410_TCNTB(4));
 357 +       } else {
 358 +               ticks_last = ticks;
 359 +               ticks_left = 0;
 360 +               __raw_writel(tcfg1 | S3C2410_TCFG1_MUX4_DIV2, S3C2410_TCFG1);
 361 +               __raw_writel(ticks_last >> 0, S3C2410_TCNTB(4));
 362 +       }
 363 +
 364 +       tcnto_last = __raw_readl(S3C2410_TCNTO(4));
 365 +       __raw_writel(tcon | S3C2410_TCON_T4MANUALUPD,
 366 +                       S3C2410_TCON);
 367 +       __raw_writel(tcon | S3C2410_TCON_T4START,
 368 +                       S3C2410_TCON);
 369 +}
 370 +
 371 +/*
 372 + * If we have already waited all the time we were supposed to wait,
 373 + * kick the timer, setting the longest allowed timeout value just
 374 + * for time-keeping.
 375 + */
 376 +static inline void s3c24xx_timer_program_idle(void)
 377 +{
 378 +       s3c24xx_timer_program(0xffff << 3);
 379 +}
 380 +
 381 +static inline void s3c24xx_timer_update(int restart)
 382 +{
 383 +       int ticks_cur = s3c24xx_timer_read();
 384 +       int jiffies_elapsed = (ticks_last - ticks_cur) >> INPUT_FREQ_SHIFT;
 385 +       int subjiffy = ticks_last - (jiffies_elapsed << INPUT_FREQ_SHIFT);
 386 +
 387 +       if (restart) {
 388 +               if (ticks_left >= (1 << INPUT_FREQ_SHIFT))
 389 +                       s3c24xx_timer_program(ticks_left);
 390 +               else
 391 +                       s3c24xx_timer_program_idle();
 392 +               ticks_last += subjiffy;
 393 +       } else
 394 +               ticks_last = subjiffy;
 395 +
 396 +       while (jiffies_elapsed --)
 397 +               timer_tick();
 398 +}
 399 +
 400 +/* Called when the timer expires.  */
 401 +static irqreturn_t s3c24xx_timer_handler(int irq, void *dev_id)
 402 +{
 403 +       tcnto_last = -1;
 404 +       s3c24xx_timer_update(1);
 405 +
 406 +       return IRQ_HANDLED;
 407 +}
 408 +
 409 +/* Called to update jiffies with time elapsed.  */
 410 +static irqreturn_t s3c24xx_timer_handler_dyn_tick(int irq, void *dev_id)
 411 +{
 412 +       s3c24xx_timer_update(0);
 413 +
 414 +       return IRQ_HANDLED;
 415 +}
 416 +
 417 +/*
 418 + * Programs the next timer interrupt needed.  Called when dynamic tick is
 419 + * enabled, and to reprogram the ticks to skip from pm_idle.  The CPU goes
 420 + * to sleep directly after this.
 421 + */
 422 +static void s3c24xx_timer_reprogram_dyn_tick(unsigned long next_jiffies)
 423 +{
 424 +       int subjiffy_left = ticks_last - s3c24xx_timer_read();
 425 +
 426 +       s3c24xx_timer_program(max((int) next_jiffies, 1) << INPUT_FREQ_SHIFT);
 427 +       ticks_last += subjiffy_left;
 428 +}
 429 +
 430 +static unsigned long s3c24xx_timer_offset_dyn_tick(void)
 431 +{
 432 +       /* TODO */
 433 +       return 0;
 434 +}
 435 +
 436 +static int s3c24xx_timer_enable_dyn_tick(void)
 437 +{
 438 +       /* Set our constant prescaler.  */
 439 +       uint32_t tcfg0 = __raw_readl(S3C2410_TCFG0);
 440 +       int prescaler =
 441 +               max(min(256, (int) pclk / (HZ << (INPUT_FREQ_SHIFT + 1))), 1);
 442 +
 443 +       tcfg0 &= ~S3C2410_TCFG_PRESCALER1_MASK;
 444 +       tcfg0 |= (prescaler - 1) << S3C2410_TCFG_PRESCALER1_SHIFT;
 445 +       __raw_writel(tcfg0, S3C2410_TCFG0);
 446 +
 447 +       /* Override handlers.  */
 448 +       s3c2410_timer_irq.handler = s3c24xx_timer_handler;
 449 +       s3c24xx_timer.offset = s3c24xx_timer_offset_dyn_tick;
 450 +
 451 +       printk(KERN_INFO "dyn_tick enabled on s3c24xx timer 4, "
 452 +                       "%li Hz pclk with prescaler %i\n", pclk, prescaler);
 453 +
 454 +       s3c24xx_timer_program_idle();
 455 +
 456 +       return 0;
 457 +}
 458 +
 459 +static int s3c24xx_timer_disable_dyn_tick(void)
 460 +{
 461 +       s3c2410_timer_irq.handler = s3c2410_timer_interrupt;
 462 +       s3c24xx_timer.offset = s3c2410_gettimeoffset;
 463 +       s3c2410_timer_setup();
 464 +
 465 +       return 0;
 466 +}
 467 +
 468 +static struct dyn_tick_timer s3c24xx_dyn_tick_timer = {
 469 +       .enable         = s3c24xx_timer_enable_dyn_tick,
 470 +       .disable        = s3c24xx_timer_disable_dyn_tick,
 471 +       .reprogram      = s3c24xx_timer_reprogram_dyn_tick,
 472 +       .handler        = s3c24xx_timer_handler_dyn_tick,
 473 +};
 474 +#endif /* CONFIG_NO_IDLE_HZ */
 475 +
 476 +struct sys_timer s3c24xx_timer = {
 477 +       .init           = s3c2410_timer_init,
 478 +       .offset         = s3c2410_gettimeoffset,
 479 +       .resume         = s3c2410_timer_resume,
 480 +#ifdef CONFIG_NO_IDLE_HZ
 481 +       .dyn_tick       = &s3c24xx_dyn_tick_timer,
 482 +#endif
 483 +};