arch/x86/kernel/cpu/cpufreq/cpufreq-nforce2.c

   1 /*
   2  * (C) 2004-2006  Sebastian Witt <se.witt@gmx.net>
   3  *
   4  *  Licensed under the terms of the GNU GPL License version 2.
   5  *  Based upon reverse engineered information
   6  *
   7  *  BIG FAT DISCLAIMER: Work in progress code. Possibly *dangerous*
   8  */
   9
  10 #include <linux/kernel.h>
  11 #include <linux/module.h>
  12 #include <linux/moduleparam.h>
  13 #include <linux/init.h>
  14 #include <linux/cpufreq.h>
  15 #include <linux/pci.h>
  16 #include <linux/delay.h>
  17
  18 #define NFORCE2_XTAL 25
  19 #define NFORCE2_BOOTFSB 0x48
  20 #define NFORCE2_PLLENABLE 0xa8
  21 #define NFORCE2_PLLREG 0xa4
  22 #define NFORCE2_PLLADR 0xa0
  23 #define NFORCE2_PLL(mul, div) (0x100000 | (mul << 8) | div)
  24
  25 #define NFORCE2_MIN_FSB 50
  26 #define NFORCE2_SAFE_DISTANCE 50
  27
  28 /* Delay in ms between FSB changes */
  29 /* #define NFORCE2_DELAY 10 */
  30
  31 /*
  32  * nforce2_chipset:
  33  * FSB is changed using the chipset
  34  */
  35 static struct pci_dev *nforce2_dev;
  36
  37 /* fid:
  38  * multiplier * 10
  39  */
  40 static int fid;
  41
  42 /* min_fsb, max_fsb:
  43  * minimum and maximum FSB (= FSB at boot time)
  44  */
  45 static int min_fsb;
  46 static int max_fsb;
  47
  48 MODULE_AUTHOR("Sebastian Witt <se.witt@gmx.net>");
  49 MODULE_DESCRIPTION("nForce2 FSB changing cpufreq driver");
  50 MODULE_LICENSE("GPL");
  51
  52 module_param(fid, int, 0444);
  53 module_param(min_fsb, int, 0444);
  54
  55 MODULE_PARM_DESC(fid, "CPU multiplier to use (11.5 = 115)");
  56 MODULE_PARM_DESC(min_fsb,
  57                 "Minimum FSB to use, if not defined: current FSB - 50");
  58
  59 #define PFX "cpufreq-nforce2: "
  60 #define dprintk(msg...) cpufreq_debug_printk(CPUFREQ_DEBUG_DRIVER, \
  61                 "cpufreq-nforce2", msg)
  62
  63 /**
  64  * nforce2_calc_fsb - calculate FSB
  65  * @pll: PLL value
  66  *
  67  *   Calculates FSB from PLL value
  68  */
  69 static int nforce2_calc_fsb(int pll)
  70 {
  71         unsigned char mul, div;
  72
  73         mul = (pll >> 8) & 0xff;
  74         div = pll & 0xff;
  75
  76         if (div > 0)
  77                 return NFORCE2_XTAL * mul / div;
  78
  79         return 0;
  80 }
  81
  82 /**
  83  * nforce2_calc_pll - calculate PLL value
  84  * @fsb: FSB
  85  *
  86  *   Calculate PLL value for given FSB
  87  */
  88 static int nforce2_calc_pll(unsigned int fsb)
  89 {
  90         unsigned char xmul, xdiv;
  91         unsigned char mul = 0, div = 0;
  92         int tried = 0;
  93
  94         /* Try to calculate multiplier and divider up to 4 times */
  95         while (((mul == 0) || (div == 0)) && (tried <= 3)) {
  96                 for (xdiv = 2; xdiv <= 0x80; xdiv++)
  97                         for (xmul = 1; xmul <= 0xfe; xmul++)
  98                                 if (nforce2_calc_fsb(NFORCE2_PLL(xmul, xdiv)) ==
  99                                     fsb + tried) {
 100                                         mul = xmul;
 101                                         div = xdiv;
 102                                 }
 103                 tried++;
 104         }
 105
 106         if ((mul == 0) || (div == 0))
 107                 return -1;
 108
 109         return NFORCE2_PLL(mul, div);
 110 }
 111
 112 /**
 113  * nforce2_write_pll - write PLL value to chipset
 114  * @pll: PLL value
 115  *
 116  *   Writes new FSB PLL value to chipset
 117  */
 118 static void nforce2_write_pll(int pll)
 119 {
 120         int temp;
 121
 122         /* Set the pll addr. to 0x00 */
 123         pci_write_config_dword(nforce2_dev, NFORCE2_PLLADR, 0);
 124
 125         /* Now write the value in all 64 registers */
 126         for (temp = 0; temp <= 0x3f; temp++)
 127                 pci_write_config_dword(nforce2_dev, NFORCE2_PLLREG, pll);
 128
 129         return;
 130 }
 131
 132 /**
 133  * nforce2_fsb_read - Read FSB
 134  *
 135  *   Read FSB from chipset
 136  *   If bootfsb != 0, return FSB at boot-time
 137  */
 138 static unsigned int nforce2_fsb_read(int bootfsb)
 139 {
 140         struct pci_dev *nforce2_sub5;
 141         u32 fsb, temp = 0;
 142
 143         /* Get chipset boot FSB from subdevice 5 (FSB at boot-time) */
 144         nforce2_sub5 = pci_get_subsys(PCI_VENDOR_ID_NVIDIA, 0x01EF,
 145                                 PCI_ANY_ID, PCI_ANY_ID, NULL);
 146         if (!nforce2_sub5)
 147                 return 0;
 148
 149         pci_read_config_dword(nforce2_sub5, NFORCE2_BOOTFSB, &fsb);
 150         fsb /= 1000000;
 151
 152         /* Check if PLL register is already set */
 153         pci_read_config_byte(nforce2_dev, NFORCE2_PLLENABLE, (u8 *)&temp);
 154
 155         if (bootfsb || !temp)
 156                 return fsb;
 157
 158         /* Use PLL register FSB value */
 159         pci_read_config_dword(nforce2_dev, NFORCE2_PLLREG, &temp);
 160         fsb = nforce2_calc_fsb(temp);
 161
 162         return fsb;
 163 }
 164
 165 /**
 166  * nforce2_set_fsb - set new FSB
 167  * @fsb: New FSB
 168  *
 169  *   Sets new FSB
 170  */
 171 static int nforce2_set_fsb(unsigned int fsb)
 172 {
 173         u32 temp = 0;
 174         unsigned int tfsb;
 175         int diff;
 176         int pll = 0;
 177
 178         if ((fsb > max_fsb) || (fsb < NFORCE2_MIN_FSB)) {
 179                 printk(KERN_ERR PFX "FSB %d is out of range!\n", fsb);
 180                 return -EINVAL;
 181         }
 182
 183         tfsb = nforce2_fsb_read(0);
 184         if (!tfsb) {
 185                 printk(KERN_ERR PFX "Error while reading the FSB\n");
 186                 return -EINVAL;
 187         }
 188
 189         /* First write? Then set actual value */
 190         pci_read_config_byte(nforce2_dev, NFORCE2_PLLENABLE, (u8 *)&temp);
 191         if (!temp) {
 192                 pll = nforce2_calc_pll(tfsb);
 193
 194                 if (pll < 0)
 195                         return -EINVAL;
 196
 197                 nforce2_write_pll(pll);
 198         }
 199
 200         /* Enable write access */
 201         temp = 0x01;
 202         pci_write_config_byte(nforce2_dev, NFORCE2_PLLENABLE, (u8)temp);
 203
 204         diff = tfsb - fsb;
 205
 206         if (!diff)
 207                 return 0;
 208
 209         while ((tfsb != fsb) && (tfsb <= max_fsb) && (tfsb >= min_fsb)) {
 210                 if (diff < 0)
 211                         tfsb++;
 212                 else
 213                         tfsb--;
 214
 215                 /* Calculate the PLL reg. value */
 216                 pll = nforce2_calc_pll(tfsb);
 217                 if (pll == -1)
 218                         return -EINVAL;
 219
 220                 nforce2_write_pll(pll);
 221 #ifdef NFORCE2_DELAY
 222                 mdelay(NFORCE2_DELAY);
 223 #endif
 224         }
 225
 226         temp = 0x40;
 227         pci_write_config_byte(nforce2_dev, NFORCE2_PLLADR, (u8)temp);
 228
 229         return 0;
 230 }
 231
 232 /**
 233  * nforce2_get - get the CPU frequency
 234  * @cpu: CPU number
 235  *
 236  * Returns the CPU frequency
 237  */
 238 static unsigned int nforce2_get(unsigned int cpu)
 239 {
 240         if (cpu)
 241                 return 0;
 242         return nforce2_fsb_read(0) * fid * 100;
 243 }
 244
 245 /**
 246  * nforce2_target - set a new CPUFreq policy
 247  * @policy: new policy
 248  * @target_freq: the target frequency
 249  * @relation: how that frequency relates to achieved frequency
 250  *  (CPUFREQ_RELATION_L or CPUFREQ_RELATION_H)
 251  *
 252  * Sets a new CPUFreq policy.
 253  */
 254 static int nforce2_target(struct cpufreq_policy *policy,
 255                           unsigned int target_freq, unsigned int relation)
 256 {
 257 /*        unsigned long         flags; */
 258         struct cpufreq_freqs freqs;
 259         unsigned int target_fsb;
 260
 261         if ((target_freq > policy->max) || (target_freq < policy->min))
 262                 return -EINVAL;
 263
 264         target_fsb = target_freq / (fid * 100);
 265
 266         freqs.old = nforce2_get(policy->cpu);
 267         freqs.new = target_fsb * fid * 100;
 268         freqs.cpu = 0;          /* Only one CPU on nForce2 platforms */
 269
 270         if (freqs.old == freqs.new)
 271                 return 0;
 272
 273         dprintk("Old CPU frequency %d kHz, new %d kHz\n",
 274                freqs.old, freqs.new);
 275
 276         cpufreq_notify_transition(&freqs, CPUFREQ_PRECHANGE);
 277
 278         /* Disable IRQs */
 279         /* local_irq_save(flags); */
 280
 281         if (nforce2_set_fsb(target_fsb) < 0)
 282                 printk(KERN_ERR PFX "Changing FSB to %d failed\n",
 283                         target_fsb);
 284         else
 285                 dprintk("Changed FSB successfully to %d\n",
 286                         target_fsb);
 287
 288         /* Enable IRQs */
 289         /* local_irq_restore(flags); */
 290
 291         cpufreq_notify_transition(&freqs, CPUFREQ_POSTCHANGE);
 292
 293         return 0;
 294 }
 295
 296 /**
 297  * nforce2_verify - verifies a new CPUFreq policy
 298  * @policy: new policy
 299  */
 300 static int nforce2_verify(struct cpufreq_policy *policy)
 301 {
 302         unsigned int fsb_pol_max;
 303
 304         fsb_pol_max = policy->max / (fid * 100);
 305
 306         if (policy->min < (fsb_pol_max * fid * 100))
 307                 policy->max = (fsb_pol_max + 1) * fid * 100;
 308
 309         cpufreq_verify_within_limits(policy,
 310                                      policy->cpuinfo.min_freq,
 311                                      policy->cpuinfo.max_freq);
 312         return 0;
 313 }
 314
 315 static int nforce2_cpu_init(struct cpufreq_policy *policy)
 316 {
 317         unsigned int fsb;
 318         unsigned int rfid;
 319
 320         /* capability check */
 321         if (policy->cpu != 0)
 322                 return -ENODEV;
 323
 324         /* Get current FSB */
 325         fsb = nforce2_fsb_read(0);
 326
 327         if (!fsb)
 328                 return -EIO;
 329
 330         /* FIX: Get FID from CPU */
 331         if (!fid) {
 332                 if (!cpu_khz) {
 333                         printk(KERN_WARNING PFX
 334                         "cpu_khz not set, can't calculate multiplier!\n");
 335                         return -ENODEV;
 336                 }
 337
 338                 fid = cpu_khz / (fsb * 100);
 339                 rfid = fid % 5;
 340
 341                 if (rfid) {
 342                         if (rfid > 2)
 343                                 fid += 5 - rfid;
 344                         else
 345                                 fid -= rfid;
 346                 }
 347         }
 348
 349         printk(KERN_INFO PFX "FSB currently at %i MHz, FID %d.%d\n", fsb,
 350                fid / 10, fid % 10);
 351
 352         /* Set maximum FSB to FSB at boot time */
 353         max_fsb = nforce2_fsb_read(1);
 354
 355         if (!max_fsb)
 356                 return -EIO;
 357
 358         if (!min_fsb)
 359                 min_fsb = max_fsb - NFORCE2_SAFE_DISTANCE;
 360
 361         if (min_fsb < NFORCE2_MIN_FSB)
 362                 min_fsb = NFORCE2_MIN_FSB;
 363
 364         /* cpuinfo and default policy values */
 365         policy->cpuinfo.min_freq = min_fsb * fid * 100;
 366         policy->cpuinfo.max_freq = max_fsb * fid * 100;
 367         policy->cpuinfo.transition_latency = CPUFREQ_ETERNAL;
 368         policy->cur = nforce2_get(policy->cpu);
 369         policy->min = policy->cpuinfo.min_freq;
 370         policy->max = policy->cpuinfo.max_freq;
 371
 372         return 0;
 373 }
 374
 375 static int nforce2_cpu_exit(struct cpufreq_policy *policy)
 376 {
 377         return 0;
 378 }
 379
 380 static struct cpufreq_driver nforce2_driver = {
 381         .name = "nforce2",
 382         .verify = nforce2_verify,
 383         .target = nforce2_target,
 384         .get = nforce2_get,
 385         .init = nforce2_cpu_init,
 386         .exit = nforce2_cpu_exit,
 387         .owner = THIS_MODULE,
 388 };
 389
 390 /**
 391  * nforce2_detect_chipset - detect the Southbridge which contains FSB PLL logic
 392  *
 393  * Detects nForce2 A2 and C1 stepping
 394  *
 395  */
 396 static unsigned int nforce2_detect_chipset(void)
 397 {
 398         nforce2_dev = pci_get_subsys(PCI_VENDOR_ID_NVIDIA,
 399                                         PCI_DEVICE_ID_NVIDIA_NFORCE2,
 400                                         PCI_ANY_ID, PCI_ANY_ID, NULL);
 401
 402         if (nforce2_dev == NULL)
 403                 return -ENODEV;
 404
 405         printk(KERN_INFO PFX "Detected nForce2 chipset revision %X\n",
 406                nforce2_dev->revision);
 407         printk(KERN_INFO PFX
 408                "FSB changing is maybe unstable and can lead to "
 409                "crashes and data loss.\n");
 410
 411         return 0;
 412 }
 413
 414 /**
 415  * nforce2_init - initializes the nForce2 CPUFreq driver
 416  *
 417  * Initializes the nForce2 FSB support. Returns -ENODEV on unsupported
 418  * devices, -EINVAL on problems during initiatization, and zero on
 419  * success.
 420  */
 421 static int __init nforce2_init(void)
 422 {
 423         /* TODO: do we need to detect the processor? */
 424
 425         /* detect chipset */
 426         if (nforce2_detect_chipset()) {
 427                 printk(KERN_INFO PFX "No nForce2 chipset.\n");
 428                 return -ENODEV;
 429         }
 430
 431         return cpufreq_register_driver(&nforce2_driver);
 432 }
 433
 434 /**
 435  * nforce2_exit - unregisters cpufreq module
 436  *
 437  *   Unregisters nForce2 FSB change support.
 438  */
 439 static void __exit nforce2_exit(void)
 440 {
 441         cpufreq_unregister_driver(&nforce2_driver);
 442 }
 443
 444 module_init(nforce2_init);
 445 module_exit(nforce2_exit);
 446