drivers/misc/cs5535-mfgpt.c

   1 /*
   2  * Driver for the CS5535/CS5536 Multi-Function General Purpose Timers (MFGPT)
   3  *
   4  * Copyright (C) 2006, Advanced Micro Devices, Inc.
   5  * Copyright (C) 2007  Andres Salomon <dilinger@debian.org>
   6  * Copyright (C) 2009  Andres Salomon <dilinger@collabora.co.uk>
   7  *
   8  * This program is free software; you can redistribute it and/or
   9  * modify it under the terms of version 2 of the GNU General Public License
  10  * as published by the Free Software Foundation.
  11  *
  12  * The MFGPTs are documented in AMD Geode CS5536 Companion Device Data Book.
  13  */
  14
  15 #include <linux/kernel.h>
  16 #include <linux/spinlock.h>
  17 #include <linux/interrupt.h>
  18 #include <linux/module.h>
  19 #include <linux/platform_device.h>
  20 #include <linux/cs5535.h>
  21 #include <linux/slab.h>
  22
  23 #define DRV_NAME "cs5535-mfgpt"
  24
  25 static int mfgpt_reset_timers;
  26 module_param_named(mfgptfix, mfgpt_reset_timers, int, 0644);
  27 MODULE_PARM_DESC(mfgptfix, "Try to reset the MFGPT timers during init; "
  28                 "required by some broken BIOSes (ie, TinyBIOS < 0.99) or kexec "
  29                 "(1 = reset the MFGPT using an undocumented bit, "
  30                 "2 = perform a soft reset by unconfiguring all timers); "
  31                 "use what works best for you.");
  32
  33 struct cs5535_mfgpt_timer {
  34         struct cs5535_mfgpt_chip *chip;
  35         int nr;
  36 };
  37
  38 static struct cs5535_mfgpt_chip {
  39         DECLARE_BITMAP(avail, MFGPT_MAX_TIMERS);
  40         resource_size_t base;
  41
  42         struct platform_device *pdev;
  43         spinlock_t lock;
  44         int initialized;
  45 } cs5535_mfgpt_chip;
  46
  47 int cs5535_mfgpt_toggle_event(struct cs5535_mfgpt_timer *timer, int cmp,
  48                 int event, int enable)
  49 {
  50         uint32_t msr, mask, value, dummy;
  51         int shift = (cmp == MFGPT_CMP1) ? 0 : 8;
  52
  53         if (!timer) {
  54                 WARN_ON(1);
  55                 return -EIO;
  56         }
  57
  58         /*
  59          * The register maps for these are described in sections 6.17.1.x of
  60          * the AMD Geode CS5536 Companion Device Data Book.
  61          */
  62         switch (event) {
  63         case MFGPT_EVENT_RESET:
  64                 /*
  65                  * XXX: According to the docs, we cannot reset timers above
  66                  * 6; that is, resets for 7 and 8 will be ignored.  Is this
  67                  * a problem?   -dilinger
  68                  */
  69                 msr = MSR_MFGPT_NR;
  70                 mask = 1 << (timer->nr + 24);
  71                 break;
  72
  73         case MFGPT_EVENT_NMI:
  74                 msr = MSR_MFGPT_NR;
  75                 mask = 1 << (timer->nr + shift);
  76                 break;
  77
  78         case MFGPT_EVENT_IRQ:
  79                 msr = MSR_MFGPT_IRQ;
  80                 mask = 1 << (timer->nr + shift);
  81                 break;
  82
  83         default:
  84                 return -EIO;
  85         }
  86
  87         rdmsr(msr, value, dummy);
  88
  89         if (enable)
  90                 value |= mask;
  91         else
  92                 value &= ~mask;
  93
  94         wrmsr(msr, value, dummy);
  95         return 0;
  96 }
  97 EXPORT_SYMBOL_GPL(cs5535_mfgpt_toggle_event);
  98
  99 int cs5535_mfgpt_set_irq(struct cs5535_mfgpt_timer *timer, int cmp, int *irq,
 100                 int enable)
 101 {
 102         uint32_t zsel, lpc, dummy;
 103         int shift;
 104
 105         if (!timer) {
 106                 WARN_ON(1);
 107                 return -EIO;
 108         }
 109
 110         /*
 111          * Unfortunately, MFGPTs come in pairs sharing their IRQ lines. If VSA
 112          * is using the same CMP of the timer's Siamese twin, the IRQ is set to
 113          * 2, and we mustn't use nor change it.
 114          * XXX: Likewise, 2 Linux drivers might clash if the 2nd overwrites the
 115          * IRQ of the 1st. This can only happen if forcing an IRQ, calling this
 116          * with *irq==0 is safe. Currently there _are_ no 2 drivers.
 117          */
 118         rdmsr(MSR_PIC_ZSEL_LOW, zsel, dummy);
 119         shift = ((cmp == MFGPT_CMP1 ? 0 : 4) + timer->nr % 4) * 4;
 120         if (((zsel >> shift) & 0xF) == 2)
 121                 return -EIO;
 122
 123         /* Choose IRQ: if none supplied, keep IRQ already set or use default */
 124         if (!*irq)
 125                 *irq = (zsel >> shift) & 0xF;
 126         if (!*irq)
 127                 *irq = CONFIG_CS5535_MFGPT_DEFAULT_IRQ;
 128
 129         /* Can't use IRQ if it's 0 (=disabled), 2, or routed to LPC */
 130         if (*irq < 1 || *irq == 2 || *irq > 15)
 131                 return -EIO;
 132         rdmsr(MSR_PIC_IRQM_LPC, lpc, dummy);
 133         if (lpc & (1 << *irq))
 134                 return -EIO;
 135
 136         /* All chosen and checked - go for it */
 137         if (cs5535_mfgpt_toggle_event(timer, cmp, MFGPT_EVENT_IRQ, enable))
 138                 return -EIO;
 139         if (enable) {
 140                 zsel = (zsel & ~(0xF << shift)) | (*irq << shift);
 141                 wrmsr(MSR_PIC_ZSEL_LOW, zsel, dummy);
 142         }
 143
 144         return 0;
 145 }
 146 EXPORT_SYMBOL_GPL(cs5535_mfgpt_set_irq);
 147
 148 struct cs5535_mfgpt_timer *cs5535_mfgpt_alloc_timer(int timer_nr, int domain)
 149 {
 150         struct cs5535_mfgpt_chip *mfgpt = &cs5535_mfgpt_chip;
 151         struct cs5535_mfgpt_timer *timer = NULL;
 152         unsigned long flags;
 153         int max;
 154
 155         if (!mfgpt->initialized)
 156                 goto done;
 157
 158         /* only allocate timers from the working domain if requested */
 159         if (domain == MFGPT_DOMAIN_WORKING)
 160                 max = 6;
 161         else
 162                 max = MFGPT_MAX_TIMERS;
 163
 164         if (timer_nr >= max) {
 165                 /* programmer error.  silly programmers! */
 166                 WARN_ON(1);
 167                 goto done;
 168         }
 169
 170         spin_lock_irqsave(&mfgpt->lock, flags);
 171         if (timer_nr < 0) {
 172                 unsigned long t;
 173
 174                 /* try to find any available timer */
 175                 t = find_first_bit(mfgpt->avail, max);
 176                 /* set timer_nr to -1 if no timers available */
 177                 timer_nr = t < max ? (int) t : -1;
 178         } else {
 179                 /* check if the requested timer's available */
 180                 if (!test_bit(timer_nr, mfgpt->avail))
 181                         timer_nr = -1;
 182         }
 183
 184         if (timer_nr >= 0)
 185                 /* if timer_nr is not -1, it's an available timer */
 186                 __clear_bit(timer_nr, mfgpt->avail);
 187         spin_unlock_irqrestore(&mfgpt->lock, flags);
 188
 189         if (timer_nr < 0)
 190                 goto done;
 191
 192         timer = kmalloc(sizeof(*timer), GFP_KERNEL);
 193         if (!timer) {
 194                 /* aw hell */
 195                 spin_lock_irqsave(&mfgpt->lock, flags);
 196                 __set_bit(timer_nr, mfgpt->avail);
 197                 spin_unlock_irqrestore(&mfgpt->lock, flags);
 198                 goto done;
 199         }
 200         timer->chip = mfgpt;
 201         timer->nr = timer_nr;
 202         dev_info(&mfgpt->pdev->dev, "registered timer %d\n", timer_nr);
 203
 204 done:
 205         return timer;
 206 }
 207 EXPORT_SYMBOL_GPL(cs5535_mfgpt_alloc_timer);
 208
 209 /*
 210  * XXX: This frees the timer memory, but never resets the actual hardware
 211  * timer.  The old geode_mfgpt code did this; it would be good to figure
 212  * out a way to actually release the hardware timer.  See comments below.
 213  */
 214 void cs5535_mfgpt_free_timer(struct cs5535_mfgpt_timer *timer)
 215 {
 216         unsigned long flags;
 217         uint16_t val;
 218
 219         /* timer can be made available again only if never set up */
 220         val = cs5535_mfgpt_read(timer, MFGPT_REG_SETUP);
 221         if (!(val & MFGPT_SETUP_SETUP)) {
 222                 spin_lock_irqsave(&timer->chip->lock, flags);
 223                 __set_bit(timer->nr, timer->chip->avail);
 224                 spin_unlock_irqrestore(&timer->chip->lock, flags);
 225         }
 226
 227         kfree(timer);
 228 }
 229 EXPORT_SYMBOL_GPL(cs5535_mfgpt_free_timer);
 230
 231 uint16_t cs5535_mfgpt_read(struct cs5535_mfgpt_timer *timer, uint16_t reg)
 232 {
 233         return inw(timer->chip->base + reg + (timer->nr * 8));
 234 }
 235 EXPORT_SYMBOL_GPL(cs5535_mfgpt_read);
 236
 237 void cs5535_mfgpt_write(struct cs5535_mfgpt_timer *timer, uint16_t reg,
 238                 uint16_t value)
 239 {
 240         outw(value, timer->chip->base + reg + (timer->nr * 8));
 241 }
 242 EXPORT_SYMBOL_GPL(cs5535_mfgpt_write);
 243
 244 /*
 245  * This is a sledgehammer that resets all MFGPT timers. This is required by
 246  * some broken BIOSes which leave the system in an unstable state
 247  * (TinyBIOS 0.98, for example; fixed in 0.99).  It's uncertain as to
 248  * whether or not this secret MSR can be used to release individual timers.
 249  * Jordan tells me that he and Mitch once played w/ it, but it's unclear
 250  * what the results of that were (and they experienced some instability).
 251  */
 252 static void reset_all_timers(void)
 253 {
 254         uint32_t val, dummy;
 255
 256         /* The following undocumented bit resets the MFGPT timers */
 257         val = 0xFF; dummy = 0;
 258         wrmsr(MSR_MFGPT_SETUP, val, dummy);
 259 }
 260
 261 /*
 262  * This is another sledgehammer to reset all MFGPT timers.
 263  * Instead of using the undocumented bit method it clears
 264  * IRQ, NMI and RESET settings.
 265  */
 266 static void soft_reset(void)
 267 {
 268         int i;
 269         struct cs5535_mfgpt_timer t;
 270
 271         for (i = 0; i < MFGPT_MAX_TIMERS; i++) {
 272                 t.nr = i;
 273
 274                 cs5535_mfgpt_toggle_event(&t, MFGPT_CMP1, MFGPT_EVENT_RESET, 0);
 275                 cs5535_mfgpt_toggle_event(&t, MFGPT_CMP2, MFGPT_EVENT_RESET, 0);
 276                 cs5535_mfgpt_toggle_event(&t, MFGPT_CMP1, MFGPT_EVENT_NMI, 0);
 277                 cs5535_mfgpt_toggle_event(&t, MFGPT_CMP2, MFGPT_EVENT_NMI, 0);
 278                 cs5535_mfgpt_toggle_event(&t, MFGPT_CMP1, MFGPT_EVENT_IRQ, 0);
 279                 cs5535_mfgpt_toggle_event(&t, MFGPT_CMP2, MFGPT_EVENT_IRQ, 0);
 280         }
 281 }
 282
 283 /*
 284  * Check whether any MFGPTs are available for the kernel to use.  In most
 285  * cases, firmware that uses AMD's VSA code will claim all timers during
 286  * bootup; we certainly don't want to take them if they're already in use.
 287  * In other cases (such as with VSAless OpenFirmware), the system firmware
 288  * leaves timers available for us to use.
 289  */
 290 static int scan_timers(struct cs5535_mfgpt_chip *mfgpt)
 291 {
 292         struct cs5535_mfgpt_timer timer = { .chip = mfgpt };
 293         unsigned long flags;
 294         int timers = 0;
 295         uint16_t val;
 296         int i;
 297
 298         /* bios workaround */
 299         if (mfgpt_reset_timers == 1)
 300                 reset_all_timers();
 301         else if (mfgpt_reset_timers == 2)
 302                 soft_reset();
 303
 304         /* just to be safe, protect this section w/ lock */
 305         spin_lock_irqsave(&mfgpt->lock, flags);
 306         for (i = 0; i < MFGPT_MAX_TIMERS; i++) {
 307                 timer.nr = i;
 308                 val = cs5535_mfgpt_read(&timer, MFGPT_REG_SETUP);
 309                 if (!(val & MFGPT_SETUP_SETUP) || mfgpt_reset_timers == 2) {
 310                         __set_bit(i, mfgpt->avail);
 311                         timers++;
 312                 }
 313         }
 314         spin_unlock_irqrestore(&mfgpt->lock, flags);
 315
 316         return timers;
 317 }
 318
 319 static int cs5535_mfgpt_probe(struct platform_device *pdev)
 320 {
 321         struct resource *res;
 322         int err = -EIO, t;
 323
 324         if (mfgpt_reset_timers < 0 || mfgpt_reset_timers > 2) {
 325                 dev_err(&pdev->dev, "Bad mfgpt_reset_timers value: %i\n",
 326                         mfgpt_reset_timers);
 327                 goto done;
 328         }
 329
 330         /* There are two ways to get the MFGPT base address; one is by
 331          * fetching it from MSR_LBAR_MFGPT, the other is by reading the
 332          * PCI BAR info.  The latter method is easier (especially across
 333          * different architectures), so we'll stick with that for now.  If
 334          * it turns out to be unreliable in the face of crappy BIOSes, we
 335          * can always go back to using MSRs.. */
 336
 337         res = platform_get_resource(pdev, IORESOURCE_IO, 0);
 338         if (!res) {
 339                 dev_err(&pdev->dev, "can't fetch device resource info\n");
 340                 goto done;
 341         }
 342
 343         if (!request_region(res->start, resource_size(res), pdev->name)) {
 344                 dev_err(&pdev->dev, "can't request region\n");
 345                 goto done;
 346         }
 347
 348         /* set up the driver-specific struct */
 349         cs5535_mfgpt_chip.base = res->start;
 350         cs5535_mfgpt_chip.pdev = pdev;
 351         spin_lock_init(&cs5535_mfgpt_chip.lock);
 352
 353         dev_info(&pdev->dev, "reserved resource region %pR\n", res);
 354
 355         /* detect the available timers */
 356         t = scan_timers(&cs5535_mfgpt_chip);
 357         dev_info(&pdev->dev, "%d MFGPT timers available\n", t);
 358         cs5535_mfgpt_chip.initialized = 1;
 359         return 0;
 360
 361 done:
 362         return err;
 363 }
 364
 365 static struct platform_driver cs5535_mfgpt_driver = {
 366         .driver = {
 367                 .name = DRV_NAME,
 368         },
 369         .probe = cs5535_mfgpt_probe,
 370 };
 371
 372
 373 static int __init cs5535_mfgpt_init(void)
 374 {
 375         return platform_driver_register(&cs5535_mfgpt_driver);
 376 }
 377
 378 module_init(cs5535_mfgpt_init);
 379
 380 MODULE_AUTHOR("Andres Salomon <dilinger@queued.net>");
 381 MODULE_DESCRIPTION("CS5535/CS5536 MFGPT timer driver");
 382 MODULE_LICENSE("GPL");
 383 MODULE_ALIAS("platform:" DRV_NAME);