drivers/misc/cs5535-mfgpt.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * Driver for the CS5535/CS5536 Multi-Function General Purpose Timers (MFGPT)
   4  *
   5  * Copyright (C) 2006, Advanced Micro Devices, Inc.
   6  * Copyright (C) 2007  Andres Salomon <dilinger@debian.org>
   7  * Copyright (C) 2009  Andres Salomon <dilinger@collabora.co.uk>
   8  *
   9  * The MFGPTs are documented in AMD Geode CS5536 Companion Device Data Book.
  10  */
  11
  12 #include <linux/kernel.h>
  13 #include <linux/spinlock.h>
  14 #include <linux/interrupt.h>
  15 #include <linux/module.h>
  16 #include <linux/platform_device.h>
  17 #include <linux/cs5535.h>
  18 #include <linux/slab.h>
  19
  20 #define DRV_NAME "cs5535-mfgpt"
  21
  22 static int mfgpt_reset_timers;
  23 module_param_named(mfgptfix, mfgpt_reset_timers, int, 0644);
  24 MODULE_PARM_DESC(mfgptfix, "Try to reset the MFGPT timers during init; "
  25                 "required by some broken BIOSes (ie, TinyBIOS < 0.99) or kexec "
  26                 "(1 = reset the MFGPT using an undocumented bit, "
  27                 "2 = perform a soft reset by unconfiguring all timers); "
  28                 "use what works best for you.");
  29
  30 struct cs5535_mfgpt_timer {
  31         struct cs5535_mfgpt_chip *chip;
  32         int nr;
  33 };
  34
  35 static struct cs5535_mfgpt_chip {
  36         DECLARE_BITMAP(avail, MFGPT_MAX_TIMERS);
  37         resource_size_t base;
  38
  39         struct platform_device *pdev;
  40         spinlock_t lock;
  41         int initialized;
  42 } cs5535_mfgpt_chip;
  43
  44 int cs5535_mfgpt_toggle_event(struct cs5535_mfgpt_timer *timer, int cmp,
  45                 int event, int enable)
  46 {
  47         uint32_t msr, mask, value, dummy;
  48         int shift = (cmp == MFGPT_CMP1) ? 0 : 8;
  49
  50         if (!timer) {
  51                 WARN_ON(1);
  52                 return -EIO;
  53         }
  54
  55         /*
  56          * The register maps for these are described in sections 6.17.1.x of
  57          * the AMD Geode CS5536 Companion Device Data Book.
  58          */
  59         switch (event) {
  60         case MFGPT_EVENT_RESET:
  61                 /*
  62                  * XXX: According to the docs, we cannot reset timers above
  63                  * 6; that is, resets for 7 and 8 will be ignored.  Is this
  64                  * a problem?   -dilinger
  65                  */
  66                 msr = MSR_MFGPT_NR;
  67                 mask = 1 << (timer->nr + 24);
  68                 break;
  69
  70         case MFGPT_EVENT_NMI:
  71                 msr = MSR_MFGPT_NR;
  72                 mask = 1 << (timer->nr + shift);
  73                 break;
  74
  75         case MFGPT_EVENT_IRQ:
  76                 msr = MSR_MFGPT_IRQ;
  77                 mask = 1 << (timer->nr + shift);
  78                 break;
  79
  80         default:
  81                 return -EIO;
  82         }
  83
  84         rdmsr(msr, value, dummy);
  85
  86         if (enable)
  87                 value |= mask;
  88         else
  89                 value &= ~mask;
  90
  91         wrmsr(msr, value, dummy);
  92         return 0;
  93 }
  94 EXPORT_SYMBOL_GPL(cs5535_mfgpt_toggle_event);
  95
  96 int cs5535_mfgpt_set_irq(struct cs5535_mfgpt_timer *timer, int cmp, int *irq,
  97                 int enable)
  98 {
  99         uint32_t zsel, lpc, dummy;
 100         int shift;
 101
 102         if (!timer) {
 103                 WARN_ON(1);
 104                 return -EIO;
 105         }
 106
 107         /*
 108          * Unfortunately, MFGPTs come in pairs sharing their IRQ lines. If VSA
 109          * is using the same CMP of the timer's Siamese twin, the IRQ is set to
 110          * 2, and we mustn't use nor change it.
 111          * XXX: Likewise, 2 Linux drivers might clash if the 2nd overwrites the
 112          * IRQ of the 1st. This can only happen if forcing an IRQ, calling this
 113          * with *irq==0 is safe. Currently there _are_ no 2 drivers.
 114          */
 115         rdmsr(MSR_PIC_ZSEL_LOW, zsel, dummy);
 116         shift = ((cmp == MFGPT_CMP1 ? 0 : 4) + timer->nr % 4) * 4;
 117         if (((zsel >> shift) & 0xF) == 2)
 118                 return -EIO;
 119
 120         /* Choose IRQ: if none supplied, keep IRQ already set or use default */
 121         if (!*irq)
 122                 *irq = (zsel >> shift) & 0xF;
 123         if (!*irq)
 124                 *irq = CONFIG_CS5535_MFGPT_DEFAULT_IRQ;
 125
 126         /* Can't use IRQ if it's 0 (=disabled), 2, or routed to LPC */
 127         if (*irq < 1 || *irq == 2 || *irq > 15)
 128                 return -EIO;
 129         rdmsr(MSR_PIC_IRQM_LPC, lpc, dummy);
 130         if (lpc & (1 << *irq))
 131                 return -EIO;
 132
 133         /* All chosen and checked - go for it */
 134         if (cs5535_mfgpt_toggle_event(timer, cmp, MFGPT_EVENT_IRQ, enable))
 135                 return -EIO;
 136         if (enable) {
 137                 zsel = (zsel & ~(0xF << shift)) | (*irq << shift);
 138                 wrmsr(MSR_PIC_ZSEL_LOW, zsel, dummy);
 139         }
 140
 141         return 0;
 142 }
 143 EXPORT_SYMBOL_GPL(cs5535_mfgpt_set_irq);
 144
 145 struct cs5535_mfgpt_timer *cs5535_mfgpt_alloc_timer(int timer_nr, int domain)
 146 {
 147         struct cs5535_mfgpt_chip *mfgpt = &cs5535_mfgpt_chip;
 148         struct cs5535_mfgpt_timer *timer = NULL;
 149         unsigned long flags;
 150         int max;
 151
 152         if (!mfgpt->initialized)
 153                 goto done;
 154
 155         /* only allocate timers from the working domain if requested */
 156         if (domain == MFGPT_DOMAIN_WORKING)
 157                 max = 6;
 158         else
 159                 max = MFGPT_MAX_TIMERS;
 160
 161         if (timer_nr >= max) {
 162                 /* programmer error.  silly programmers! */
 163                 WARN_ON(1);
 164                 goto done;
 165         }
 166
 167         spin_lock_irqsave(&mfgpt->lock, flags);
 168         if (timer_nr < 0) {
 169                 unsigned long t;
 170
 171                 /* try to find any available timer */
 172                 t = find_first_bit(mfgpt->avail, max);
 173                 /* set timer_nr to -1 if no timers available */
 174                 timer_nr = t < max ? (int) t : -1;
 175         } else {
 176                 /* check if the requested timer's available */
 177                 if (!test_bit(timer_nr, mfgpt->avail))
 178                         timer_nr = -1;
 179         }
 180
 181         if (timer_nr >= 0)
 182                 /* if timer_nr is not -1, it's an available timer */
 183                 __clear_bit(timer_nr, mfgpt->avail);
 184         spin_unlock_irqrestore(&mfgpt->lock, flags);
 185
 186         if (timer_nr < 0)
 187                 goto done;
 188
 189         timer = kmalloc(sizeof(*timer), GFP_KERNEL);
 190         if (!timer) {
 191                 /* aw hell */
 192                 spin_lock_irqsave(&mfgpt->lock, flags);
 193                 __set_bit(timer_nr, mfgpt->avail);
 194                 spin_unlock_irqrestore(&mfgpt->lock, flags);
 195                 goto done;
 196         }
 197         timer->chip = mfgpt;
 198         timer->nr = timer_nr;
 199         dev_info(&mfgpt->pdev->dev, "registered timer %d\n", timer_nr);
 200
 201 done:
 202         return timer;
 203 }
 204 EXPORT_SYMBOL_GPL(cs5535_mfgpt_alloc_timer);
 205
 206 /*
 207  * XXX: This frees the timer memory, but never resets the actual hardware
 208  * timer.  The old geode_mfgpt code did this; it would be good to figure
 209  * out a way to actually release the hardware timer.  See comments below.
 210  */
 211 void cs5535_mfgpt_free_timer(struct cs5535_mfgpt_timer *timer)
 212 {
 213         unsigned long flags;
 214         uint16_t val;
 215
 216         /* timer can be made available again only if never set up */
 217         val = cs5535_mfgpt_read(timer, MFGPT_REG_SETUP);
 218         if (!(val & MFGPT_SETUP_SETUP)) {
 219                 spin_lock_irqsave(&timer->chip->lock, flags);
 220                 __set_bit(timer->nr, timer->chip->avail);
 221                 spin_unlock_irqrestore(&timer->chip->lock, flags);
 222         }
 223
 224         kfree(timer);
 225 }
 226 EXPORT_SYMBOL_GPL(cs5535_mfgpt_free_timer);
 227
 228 uint16_t cs5535_mfgpt_read(struct cs5535_mfgpt_timer *timer, uint16_t reg)
 229 {
 230         return inw(timer->chip->base + reg + (timer->nr * 8));
 231 }
 232 EXPORT_SYMBOL_GPL(cs5535_mfgpt_read);
 233
 234 void cs5535_mfgpt_write(struct cs5535_mfgpt_timer *timer, uint16_t reg,
 235                 uint16_t value)
 236 {
 237         outw(value, timer->chip->base + reg + (timer->nr * 8));
 238 }
 239 EXPORT_SYMBOL_GPL(cs5535_mfgpt_write);
 240
 241 /*
 242  * This is a sledgehammer that resets all MFGPT timers. This is required by
 243  * some broken BIOSes which leave the system in an unstable state
 244  * (TinyBIOS 0.98, for example; fixed in 0.99).  It's uncertain as to
 245  * whether or not this secret MSR can be used to release individual timers.
 246  * Jordan tells me that he and Mitch once played w/ it, but it's unclear
 247  * what the results of that were (and they experienced some instability).
 248  */
 249 static void reset_all_timers(void)
 250 {
 251         uint32_t val, dummy;
 252
 253         /* The following undocumented bit resets the MFGPT timers */
 254         val = 0xFF; dummy = 0;
 255         wrmsr(MSR_MFGPT_SETUP, val, dummy);
 256 }
 257
 258 /*
 259  * This is another sledgehammer to reset all MFGPT timers.
 260  * Instead of using the undocumented bit method it clears
 261  * IRQ, NMI and RESET settings.
 262  */
 263 static void soft_reset(void)
 264 {
 265         int i;
 266         struct cs5535_mfgpt_timer t;
 267
 268         for (i = 0; i < MFGPT_MAX_TIMERS; i++) {
 269                 t.nr = i;
 270
 271                 cs5535_mfgpt_toggle_event(&t, MFGPT_CMP1, MFGPT_EVENT_RESET, 0);
 272                 cs5535_mfgpt_toggle_event(&t, MFGPT_CMP2, MFGPT_EVENT_RESET, 0);
 273                 cs5535_mfgpt_toggle_event(&t, MFGPT_CMP1, MFGPT_EVENT_NMI, 0);
 274                 cs5535_mfgpt_toggle_event(&t, MFGPT_CMP2, MFGPT_EVENT_NMI, 0);
 275                 cs5535_mfgpt_toggle_event(&t, MFGPT_CMP1, MFGPT_EVENT_IRQ, 0);
 276                 cs5535_mfgpt_toggle_event(&t, MFGPT_CMP2, MFGPT_EVENT_IRQ, 0);
 277         }
 278 }
 279
 280 /*
 281  * Check whether any MFGPTs are available for the kernel to use.  In most
 282  * cases, firmware that uses AMD's VSA code will claim all timers during
 283  * bootup; we certainly don't want to take them if they're already in use.
 284  * In other cases (such as with VSAless OpenFirmware), the system firmware
 285  * leaves timers available for us to use.
 286  */
 287 static int scan_timers(struct cs5535_mfgpt_chip *mfgpt)
 288 {
 289         struct cs5535_mfgpt_timer timer = { .chip = mfgpt };
 290         unsigned long flags;
 291         int timers = 0;
 292         uint16_t val;
 293         int i;
 294
 295         /* bios workaround */
 296         if (mfgpt_reset_timers == 1)
 297                 reset_all_timers();
 298         else if (mfgpt_reset_timers == 2)
 299                 soft_reset();
 300
 301         /* just to be safe, protect this section w/ lock */
 302         spin_lock_irqsave(&mfgpt->lock, flags);
 303         for (i = 0; i < MFGPT_MAX_TIMERS; i++) {
 304                 timer.nr = i;
 305                 val = cs5535_mfgpt_read(&timer, MFGPT_REG_SETUP);
 306                 if (!(val & MFGPT_SETUP_SETUP) || mfgpt_reset_timers == 2) {
 307                         __set_bit(i, mfgpt->avail);
 308                         timers++;
 309                 }
 310         }
 311         spin_unlock_irqrestore(&mfgpt->lock, flags);
 312
 313         return timers;
 314 }
 315
 316 static int cs5535_mfgpt_probe(struct platform_device *pdev)
 317 {
 318         struct resource *res;
 319         int err = -EIO, t;
 320
 321         if (mfgpt_reset_timers < 0 || mfgpt_reset_timers > 2) {
 322                 dev_err(&pdev->dev, "Bad mfgpt_reset_timers value: %i\n",
 323                         mfgpt_reset_timers);
 324                 goto done;
 325         }
 326
 327         /* There are two ways to get the MFGPT base address; one is by
 328          * fetching it from MSR_LBAR_MFGPT, the other is by reading the
 329          * PCI BAR info.  The latter method is easier (especially across
 330          * different architectures), so we'll stick with that for now.  If
 331          * it turns out to be unreliable in the face of crappy BIOSes, we
 332          * can always go back to using MSRs.. */
 333
 334         res = platform_get_resource(pdev, IORESOURCE_IO, 0);
 335         if (!res) {
 336                 dev_err(&pdev->dev, "can't fetch device resource info\n");
 337                 goto done;
 338         }
 339
 340         if (!request_region(res->start, resource_size(res), pdev->name)) {
 341                 dev_err(&pdev->dev, "can't request region\n");
 342                 goto done;
 343         }
 344
 345         /* set up the driver-specific struct */
 346         cs5535_mfgpt_chip.base = res->start;
 347         cs5535_mfgpt_chip.pdev = pdev;
 348         spin_lock_init(&cs5535_mfgpt_chip.lock);
 349
 350         dev_info(&pdev->dev, "reserved resource region %pR\n", res);
 351
 352         /* detect the available timers */
 353         t = scan_timers(&cs5535_mfgpt_chip);
 354         dev_info(&pdev->dev, "%d MFGPT timers available\n", t);
 355         cs5535_mfgpt_chip.initialized = 1;
 356         return 0;
 357
 358 done:
 359         return err;
 360 }
 361
 362 static struct platform_driver cs5535_mfgpt_driver = {
 363         .driver = {
 364                 .name = DRV_NAME,
 365         },
 366         .probe = cs5535_mfgpt_probe,
 367 };
 368
 369
 370 static int __init cs5535_mfgpt_init(void)
 371 {
 372         return platform_driver_register(&cs5535_mfgpt_driver);
 373 }
 374
 375 module_init(cs5535_mfgpt_init);
 376
 377 MODULE_AUTHOR("Andres Salomon <dilinger@queued.net>");
 378 MODULE_DESCRIPTION("CS5535/CS5536 MFGPT timer driver");
 379 MODULE_LICENSE("GPL");
 380 MODULE_ALIAS("platform:" DRV_NAME);