arch/arm/mach-at91/clock.c

   1 /*
   2  * linux/arch/arm/mach-at91/clock.c
   3  *
   4  * Copyright (C) 2005 David Brownell
   5  * Copyright (C) 2005 Ivan Kokshaysky
   6  *
   7  * This program is free software; you can redistribute it and/or modify
   8  * it under the terms of the GNU General Public License as published by
   9  * the Free Software Foundation; either version 2 of the License, or
  10  * (at your option) any later version.
  11  */
  12
  13 #include <linux/module.h>
  14 #include <linux/kernel.h>
  15 #include <linux/init.h>
  16 #include <linux/fs.h>
  17 #include <linux/debugfs.h>
  18 #include <linux/seq_file.h>
  19 #include <linux/list.h>
  20 #include <linux/errno.h>
  21 #include <linux/err.h>
  22 #include <linux/spinlock.h>
  23 #include <linux/delay.h>
  24 #include <linux/clk.h>
  25
  26 #include <asm/semaphore.h>
  27 #include <asm/io.h>
  28 #include <asm/mach-types.h>
  29
  30 #include <asm/hardware.h>
  31 #include <asm/arch/at91_pmc.h>
  32 #include <asm/arch/cpu.h>
  33
  34 #include "clock.h"
  35
  36
  37 /*
  38  * There's a lot more which can be done with clocks, including cpufreq
  39  * integration, slow clock mode support (for system suspend), letting
  40  * PLLB be used at other rates (on boards that don't need USB), etc.
  41  */
  42
  43 #define clk_is_primary(x)       ((x)->type & CLK_TYPE_PRIMARY)
  44 #define clk_is_programmable(x)  ((x)->type & CLK_TYPE_PROGRAMMABLE)
  45 #define clk_is_peripheral(x)    ((x)->type & CLK_TYPE_PERIPHERAL)
  46 #define clk_is_sys(x)           ((x)->type & CLK_TYPE_SYSTEM)
  47
  48
  49 static LIST_HEAD(clocks);
  50 static DEFINE_SPINLOCK(clk_lock);
  51
  52 static u32 at91_pllb_usb_init;
  53
  54 /*
  55  * Four primary clock sources:  two crystal oscillators (32K, main), and
  56  * two PLLs.  PLLA usually runs the master clock; and PLLB must run at
  57  * 48 MHz (unless no USB function clocks are needed).  The main clock and
  58  * both PLLs are turned off to run in "slow clock mode" (system suspend).
  59  */
  60 static struct clk clk32k = {
  61         .name           = "clk32k",
  62         .rate_hz        = AT91_SLOW_CLOCK,
  63         .users          = 1,            /* always on */
  64         .id             = 0,
  65         .type           = CLK_TYPE_PRIMARY,
  66 };
  67 static struct clk main_clk = {
  68         .name           = "main",
  69         .pmc_mask       = AT91_PMC_MOSCS,       /* in PMC_SR */
  70         .id             = 1,
  71         .type           = CLK_TYPE_PRIMARY,
  72 };
  73 static struct clk plla = {
  74         .name           = "plla",
  75         .parent         = &main_clk,
  76         .pmc_mask       = AT91_PMC_LOCKA,       /* in PMC_SR */
  77         .id             = 2,
  78         .type           = CLK_TYPE_PRIMARY | CLK_TYPE_PLL,
  79 };
  80
  81 static void pllb_mode(struct clk *clk, int is_on)
  82 {
  83         u32     value;
  84
  85         if (is_on) {
  86                 is_on = AT91_PMC_LOCKB;
  87                 value = at91_pllb_usb_init;
  88         } else
  89                 value = 0;
  90
  91         // REVISIT: Add work-around for AT91RM9200 Errata #26 ?
  92         at91_sys_write(AT91_CKGR_PLLBR, value);
  93
  94         do {
  95                 cpu_relax();
  96         } while ((at91_sys_read(AT91_PMC_SR) & AT91_PMC_LOCKB) != is_on);
  97 }
  98
  99 static struct clk pllb = {
 100         .name           = "pllb",
 101         .parent         = &main_clk,
 102         .pmc_mask       = AT91_PMC_LOCKB,       /* in PMC_SR */
 103         .mode           = pllb_mode,
 104         .id             = 3,
 105         .type           = CLK_TYPE_PRIMARY | CLK_TYPE_PLL,
 106 };
 107
 108 static void pmc_sys_mode(struct clk *clk, int is_on)
 109 {
 110         if (is_on)
 111                 at91_sys_write(AT91_PMC_SCER, clk->pmc_mask);
 112         else
 113                 at91_sys_write(AT91_PMC_SCDR, clk->pmc_mask);
 114 }
 115
 116 /* USB function clocks (PLLB must be 48 MHz) */
 117 static struct clk udpck = {
 118         .name           = "udpck",
 119         .parent         = &pllb,
 120         .mode           = pmc_sys_mode,
 121 };
 122 static struct clk uhpck = {
 123         .name           = "uhpck",
 124         .parent         = &pllb,
 125         .mode           = pmc_sys_mode,
 126 };
 127
 128
 129 /*
 130  * The master clock is divided from the CPU clock (by 1-4).  It's used for
 131  * memory, interfaces to on-chip peripherals, the AIC, and sometimes more
 132  * (e.g baud rate generation).  It's sourced from one of the primary clocks.
 133  */
 134 static struct clk mck = {
 135         .name           = "mck",
 136         .pmc_mask       = AT91_PMC_MCKRDY,      /* in PMC_SR */
 137 };
 138
 139 static void pmc_periph_mode(struct clk *clk, int is_on)
 140 {
 141         if (is_on)
 142                 at91_sys_write(AT91_PMC_PCER, clk->pmc_mask);
 143         else
 144                 at91_sys_write(AT91_PMC_PCDR, clk->pmc_mask);
 145 }
 146
 147 static struct clk __init *at91_css_to_clk(unsigned long css)
 148 {
 149         switch (css) {
 150                 case AT91_PMC_CSS_SLOW:
 151                         return &clk32k;
 152                 case AT91_PMC_CSS_MAIN:
 153                         return &main_clk;
 154                 case AT91_PMC_CSS_PLLA:
 155                         return &plla;
 156                 case AT91_PMC_CSS_PLLB:
 157                         return &pllb;
 158         }
 159
 160         return NULL;
 161 }
 162
 163 /*
 164  * Associate a particular clock with a function (eg, "uart") and device.
 165  * The drivers can then request the same 'function' with several different
 166  * devices and not care about which clock name to use.
 167  */
 168 void __init at91_clock_associate(const char *id, struct device *dev, const char *func)
 169 {
 170         struct clk *clk = clk_get(NULL, id);
 171
 172         if (!dev || !clk || !IS_ERR(clk_get(dev, func)))
 173                 return;
 174
 175         clk->function = func;
 176         clk->dev = dev;
 177 }
 178
 179 /* clocks cannot be de-registered no refcounting necessary */
 180 struct clk *clk_get(struct device *dev, const char *id)
 181 {
 182         struct clk *clk;
 183
 184         list_for_each_entry(clk, &clocks, node) {
 185                 if (strcmp(id, clk->name) == 0)
 186                         return clk;
 187                 if (clk->function && (dev == clk->dev) && strcmp(id, clk->function) == 0)
 188                         return clk;
 189         }
 190
 191         return ERR_PTR(-ENOENT);
 192 }
 193 EXPORT_SYMBOL(clk_get);
 194
 195 void clk_put(struct clk *clk)
 196 {
 197 }
 198 EXPORT_SYMBOL(clk_put);
 199
 200 static void __clk_enable(struct clk *clk)
 201 {
 202         if (clk->parent)
 203                 __clk_enable(clk->parent);
 204         if (clk->users++ == 0 && clk->mode)
 205                 clk->mode(clk, 1);
 206 }
 207
 208 int clk_enable(struct clk *clk)
 209 {
 210         unsigned long   flags;
 211
 212         spin_lock_irqsave(&clk_lock, flags);
 213         __clk_enable(clk);
 214         spin_unlock_irqrestore(&clk_lock, flags);
 215         return 0;
 216 }
 217 EXPORT_SYMBOL(clk_enable);
 218
 219 static void __clk_disable(struct clk *clk)
 220 {
 221         BUG_ON(clk->users == 0);
 222         if (--clk->users == 0 && clk->mode)
 223                 clk->mode(clk, 0);
 224         if (clk->parent)
 225                 __clk_disable(clk->parent);
 226 }
 227
 228 void clk_disable(struct clk *clk)
 229 {
 230         unsigned long   flags;
 231
 232         spin_lock_irqsave(&clk_lock, flags);
 233         __clk_disable(clk);
 234         spin_unlock_irqrestore(&clk_lock, flags);
 235 }
 236 EXPORT_SYMBOL(clk_disable);
 237
 238 unsigned long clk_get_rate(struct clk *clk)
 239 {
 240         unsigned long   flags;
 241         unsigned long   rate;
 242
 243         spin_lock_irqsave(&clk_lock, flags);
 244         for (;;) {
 245                 rate = clk->rate_hz;
 246                 if (rate || !clk->parent)
 247                         break;
 248                 clk = clk->parent;
 249         }
 250         spin_unlock_irqrestore(&clk_lock, flags);
 251         return rate;
 252 }
 253 EXPORT_SYMBOL(clk_get_rate);
 254
 255 /*------------------------------------------------------------------------*/
 256
 257 #ifdef CONFIG_AT91_PROGRAMMABLE_CLOCKS
 258
 259 /*
 260  * For now, only the programmable clocks support reparenting (MCK could
 261  * do this too, with care) or rate changing (the PLLs could do this too,
 262  * ditto MCK but that's more for cpufreq).  Drivers may reparent to get
 263  * a better rate match; we don't.
 264  */
 265
 266 long clk_round_rate(struct clk *clk, unsigned long rate)
 267 {
 268         unsigned long   flags;
 269         unsigned        prescale;
 270         unsigned long   actual;
 271
 272         if (!clk_is_programmable(clk))
 273                 return -EINVAL;
 274         spin_lock_irqsave(&clk_lock, flags);
 275
 276         actual = clk->parent->rate_hz;
 277         for (prescale = 0; prescale < 7; prescale++) {
 278                 if (actual && actual <= rate)
 279                         break;
 280                 actual >>= 1;
 281         }
 282
 283         spin_unlock_irqrestore(&clk_lock, flags);
 284         return (prescale < 7) ? actual : -ENOENT;
 285 }
 286 EXPORT_SYMBOL(clk_round_rate);
 287
 288 int clk_set_rate(struct clk *clk, unsigned long rate)
 289 {
 290         unsigned long   flags;
 291         unsigned        prescale;
 292         unsigned long   actual;
 293
 294         if (!clk_is_programmable(clk))
 295                 return -EINVAL;
 296         if (clk->users)
 297                 return -EBUSY;
 298         spin_lock_irqsave(&clk_lock, flags);
 299
 300         actual = clk->parent->rate_hz;
 301         for (prescale = 0; prescale < 7; prescale++) {
 302                 if (actual && actual <= rate) {
 303                         u32     pckr;
 304
 305                         pckr = at91_sys_read(AT91_PMC_PCKR(clk->id));
 306                         pckr &= AT91_PMC_CSS_PLLB;      /* clock selection */
 307                         pckr |= prescale << 2;
 308                         at91_sys_write(AT91_PMC_PCKR(clk->id), pckr);
 309                         clk->rate_hz = actual;
 310                         break;
 311                 }
 312                 actual >>= 1;
 313         }
 314
 315         spin_unlock_irqrestore(&clk_lock, flags);
 316         return (prescale < 7) ? actual : -ENOENT;
 317 }
 318 EXPORT_SYMBOL(clk_set_rate);
 319
 320 struct clk *clk_get_parent(struct clk *clk)
 321 {
 322         return clk->parent;
 323 }
 324 EXPORT_SYMBOL(clk_get_parent);
 325
 326 int clk_set_parent(struct clk *clk, struct clk *parent)
 327 {
 328         unsigned long   flags;
 329
 330         if (clk->users)
 331                 return -EBUSY;
 332         if (!clk_is_primary(parent) || !clk_is_programmable(clk))
 333                 return -EINVAL;
 334         spin_lock_irqsave(&clk_lock, flags);
 335
 336         clk->rate_hz = parent->rate_hz;
 337         clk->parent = parent;
 338         at91_sys_write(AT91_PMC_PCKR(clk->id), parent->id);
 339
 340         spin_unlock_irqrestore(&clk_lock, flags);
 341         return 0;
 342 }
 343 EXPORT_SYMBOL(clk_set_parent);
 344
 345 /* establish PCK0..PCK3 parentage and rate */
 346 static void init_programmable_clock(struct clk *clk)
 347 {
 348         struct clk      *parent;
 349         u32             pckr;
 350
 351         pckr = at91_sys_read(AT91_PMC_PCKR(clk->id));
 352         parent = at91_css_to_clk(pckr & AT91_PMC_CSS);
 353         clk->parent = parent;
 354         clk->rate_hz = parent->rate_hz / (1 << ((pckr >> 2) & 3));
 355 }
 356
 357 #endif  /* CONFIG_AT91_PROGRAMMABLE_CLOCKS */
 358
 359 /*------------------------------------------------------------------------*/
 360
 361 #ifdef CONFIG_DEBUG_FS
 362
 363 static int at91_clk_show(struct seq_file *s, void *unused)
 364 {
 365         u32             scsr, pcsr, sr;
 366         struct clk      *clk;
 367
 368         seq_printf(s, "SCSR = %8x\n", scsr = at91_sys_read(AT91_PMC_SCSR));
 369         seq_printf(s, "PCSR = %8x\n", pcsr = at91_sys_read(AT91_PMC_PCSR));
 370         seq_printf(s, "MOR  = %8x\n", at91_sys_read(AT91_CKGR_MOR));
 371         seq_printf(s, "MCFR = %8x\n", at91_sys_read(AT91_CKGR_MCFR));
 372         seq_printf(s, "PLLA = %8x\n", at91_sys_read(AT91_CKGR_PLLAR));
 373         seq_printf(s, "PLLB = %8x\n", at91_sys_read(AT91_CKGR_PLLBR));
 374         seq_printf(s, "MCKR = %8x\n", at91_sys_read(AT91_PMC_MCKR));
 375         seq_printf(s, "SR   = %8x\n", sr = at91_sys_read(AT91_PMC_SR));
 376
 377         seq_printf(s, "\n");
 378
 379         list_for_each_entry(clk, &clocks, node) {
 380                 char    *state;
 381
 382                 if (clk->mode == pmc_sys_mode)
 383                         state = (scsr & clk->pmc_mask) ? "on" : "off";
 384                 else if (clk->mode == pmc_periph_mode)
 385                         state = (pcsr & clk->pmc_mask) ? "on" : "off";
 386                 else if (clk->pmc_mask)
 387                         state = (sr & clk->pmc_mask) ? "on" : "off";
 388                 else if (clk == &clk32k || clk == &main_clk)
 389                         state = "on";
 390                 else
 391                         state = "";
 392
 393                 seq_printf(s, "%-10s users=%2d %-3s %9ld Hz %s\n",
 394                         clk->name, clk->users, state, clk_get_rate(clk),
 395                         clk->parent ? clk->parent->name : "");
 396         }
 397         return 0;
 398 }
 399
 400 static int at91_clk_open(struct inode *inode, struct file *file)
 401 {
 402         return single_open(file, at91_clk_show, NULL);
 403 }
 404
 405 static const struct file_operations at91_clk_operations = {
 406         .open           = at91_clk_open,
 407         .read           = seq_read,
 408         .llseek         = seq_lseek,
 409         .release        = single_release,
 410 };
 411
 412 static int __init at91_clk_debugfs_init(void)
 413 {
 414         /* /sys/kernel/debug/at91_clk */
 415         (void) debugfs_create_file("at91_clk", S_IFREG | S_IRUGO, NULL, NULL, &at91_clk_operations);
 416
 417         return 0;
 418 }
 419 postcore_initcall(at91_clk_debugfs_init);
 420
 421 #endif
 422
 423 /*------------------------------------------------------------------------*/
 424
 425 /* Register a new clock */
 426 int __init clk_register(struct clk *clk)
 427 {
 428         if (clk_is_peripheral(clk)) {
 429                 clk->parent = &mck;
 430                 clk->mode = pmc_periph_mode;
 431                 list_add_tail(&clk->node, &clocks);
 432         }
 433         else if (clk_is_sys(clk)) {
 434                 clk->parent = &mck;
 435                 clk->mode = pmc_sys_mode;
 436
 437                 list_add_tail(&clk->node, &clocks);
 438         }
 439 #ifdef CONFIG_AT91_PROGRAMMABLE_CLOCKS
 440         else if (clk_is_programmable(clk)) {
 441                 clk->mode = pmc_sys_mode;
 442                 init_programmable_clock(clk);
 443                 list_add_tail(&clk->node, &clocks);
 444         }
 445 #endif
 446
 447         return 0;
 448 }
 449
 450
 451 /*------------------------------------------------------------------------*/
 452
 453 static u32 __init at91_pll_rate(struct clk *pll, u32 freq, u32 reg)
 454 {
 455         unsigned mul, div;
 456
 457         div = reg & 0xff;
 458         mul = (reg >> 16) & 0x7ff;
 459         if (div && mul) {
 460                 freq /= div;
 461                 freq *= mul + 1;
 462         } else
 463                 freq = 0;
 464
 465         return freq;
 466 }
 467
 468 static u32 __init at91_usb_rate(struct clk *pll, u32 freq, u32 reg)
 469 {
 470         if (pll == &pllb && (reg & AT91_PMC_USB96M))
 471                 return freq / 2;
 472         else
 473                 return freq;
 474 }
 475
 476 static unsigned __init at91_pll_calc(unsigned main_freq, unsigned out_freq)
 477 {
 478         unsigned i, div = 0, mul = 0, diff = 1 << 30;
 479         unsigned ret = (out_freq > 155000000) ? 0xbe00 : 0x3e00;
 480
 481         /* PLL output max 240 MHz (or 180 MHz per errata) */
 482         if (out_freq > 240000000)
 483                 goto fail;
 484
 485         for (i = 1; i < 256; i++) {
 486                 int diff1;
 487                 unsigned input, mul1;
 488
 489                 /*
 490                  * PLL input between 1MHz and 32MHz per spec, but lower
 491                  * frequences seem necessary in some cases so allow 100K.
 492                  */
 493                 input = main_freq / i;
 494                 if (input < 100000)
 495                         continue;
 496                 if (input > 32000000)
 497                         continue;
 498
 499                 mul1 = out_freq / input;
 500                 if (mul1 > 2048)
 501                         continue;
 502                 if (mul1 < 2)
 503                         goto fail;
 504
 505                 diff1 = out_freq - input * mul1;
 506                 if (diff1 < 0)
 507                         diff1 = -diff1;
 508                 if (diff > diff1) {
 509                         diff = diff1;
 510                         div = i;
 511                         mul = mul1;
 512                         if (diff == 0)
 513                                 break;
 514                 }
 515         }
 516         if (i == 256 && diff > (out_freq >> 5))
 517                 goto fail;
 518         return ret | ((mul - 1) << 16) | div;
 519 fail:
 520         return 0;
 521 }
 522
 523 static struct clk *const standard_pmc_clocks[] __initdata = {
 524         /* four primary clocks */
 525         &clk32k,
 526         &main_clk,
 527         &plla,
 528         &pllb,
 529
 530         /* PLLB children (USB) */
 531         &udpck,
 532         &uhpck,
 533
 534         /* MCK */
 535         &mck
 536 };
 537
 538 int __init at91_clock_init(unsigned long main_clock)
 539 {
 540         unsigned tmp, freq, mckr;
 541         int i;
 542
 543         /*
 544          * When the bootloader initialized the main oscillator correctly,
 545          * there's no problem using the cycle counter.  But if it didn't,
 546          * or when using oscillator bypass mode, we must be told the speed
 547          * of the main clock.
 548          */
 549         if (!main_clock) {
 550                 do {
 551                         tmp = at91_sys_read(AT91_CKGR_MCFR);
 552                 } while (!(tmp & AT91_PMC_MAINRDY));
 553                 main_clock = (tmp & AT91_PMC_MAINF) * (AT91_SLOW_CLOCK / 16);
 554         }
 555         main_clk.rate_hz = main_clock;
 556
 557         /* report if PLLA is more than mildly overclocked */
 558         plla.rate_hz = at91_pll_rate(&plla, main_clock, at91_sys_read(AT91_CKGR_PLLAR));
 559         if (plla.rate_hz > 209000000)
 560                 pr_info("Clocks: PLLA overclocked, %ld MHz\n", plla.rate_hz / 1000000);
 561
 562         /*
 563          * USB clock init:  choose 48 MHz PLLB value,
 564          * disable 48MHz clock during usb peripheral suspend.
 565          *
 566          * REVISIT:  assumes MCK doesn't derive from PLLB!
 567          */
 568         at91_pllb_usb_init = at91_pll_calc(main_clock, 48000000 * 2) | AT91_PMC_USB96M;
 569         pllb.rate_hz = at91_pll_rate(&pllb, main_clock, at91_pllb_usb_init);
 570         if (cpu_is_at91rm9200()) {
 571                 uhpck.pmc_mask = AT91RM9200_PMC_UHP;
 572                 udpck.pmc_mask = AT91RM9200_PMC_UDP;
 573                 at91_sys_write(AT91_PMC_SCER, AT91RM9200_PMC_MCKUDP);
 574         } else if (cpu_is_at91sam9260() || cpu_is_at91sam9261() || cpu_is_at91sam9263()) {
 575                 uhpck.pmc_mask = AT91SAM926x_PMC_UHP;
 576                 udpck.pmc_mask = AT91SAM926x_PMC_UDP;
 577         }
 578         at91_sys_write(AT91_CKGR_PLLBR, 0);
 579
 580         udpck.rate_hz = at91_usb_rate(&pllb, pllb.rate_hz, at91_pllb_usb_init);
 581         uhpck.rate_hz = at91_usb_rate(&pllb, pllb.rate_hz, at91_pllb_usb_init);
 582
 583         /*
 584          * MCK and CPU derive from one of those primary clocks.
 585          * For now, assume this parentage won't change.
 586          */
 587         mckr = at91_sys_read(AT91_PMC_MCKR);
 588         mck.parent = at91_css_to_clk(mckr & AT91_PMC_CSS);
 589         freq = mck.parent->rate_hz;
 590         freq /= (1 << ((mckr >> 2) & 3));               /* prescale */
 591         mck.rate_hz = freq / (1 + ((mckr >> 8) & 3));   /* mdiv */
 592
 593         /* Register the PMC's standard clocks */
 594         for (i = 0; i < ARRAY_SIZE(standard_pmc_clocks); i++)
 595                 list_add_tail(&standard_pmc_clocks[i]->node, &clocks);
 596
 597         /* MCK and CPU clock are "always on" */
 598         clk_enable(&mck);
 599
 600         printk("Clocks: CPU %u MHz, master %u MHz, main %u.%03u MHz\n",
 601                 freq / 1000000, (unsigned) mck.rate_hz / 1000000,
 602                 (unsigned) main_clock / 1000000,
 603                 ((unsigned) main_clock % 1000000) / 1000);
 604
 605         return 0;
 606 }
 607
 608 /*
 609  * Several unused clocks may be active.  Turn them off.
 610  */
 611 static int __init at91_clock_reset(void)
 612 {
 613         unsigned long pcdr = 0;
 614         unsigned long scdr = 0;
 615         struct clk *clk;
 616
 617         list_for_each_entry(clk, &clocks, node) {
 618                 if (clk->users > 0)
 619                         continue;
 620
 621                 if (clk->mode == pmc_periph_mode)
 622                         pcdr |= clk->pmc_mask;
 623
 624                 if (clk->mode == pmc_sys_mode)
 625                         scdr |= clk->pmc_mask;
 626
 627                 pr_debug("Clocks: disable unused %s\n", clk->name);
 628         }
 629
 630         at91_sys_write(AT91_PMC_PCDR, pcdr);
 631         at91_sys_write(AT91_PMC_SCDR, scdr);
 632
 633         return 0;
 634 }
 635 late_initcall(at91_clock_reset);