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