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); 381