2 * (C) 2004 Sebastian Witt <se.witt@gmx.net>
4 * Licensed under the terms of the GNU GPL License version 2.
5 * Based upon reverse engineered information
7 * BIG FAT DISCLAIMER: Work in progress code. Possibly *dangerous*
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>
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)
25 #define NFORCE2_MIN_FSB 50
26 #define NFORCE2_SAFE_DISTANCE 50
28 /* Delay in ms between FSB changes */
29 //#define NFORCE2_DELAY 10
32 * FSB is changed using the chipset
34 static struct pci_dev *nforce2_chipset_dev;
42 * minimum and maximum FSB (= FSB at boot time)
44 static int min_fsb = 0;
45 static int max_fsb = 0;
47 MODULE_AUTHOR("Sebastian Witt <se.witt@gmx.net>");
48 MODULE_DESCRIPTION("nForce2 FSB changing cpufreq driver");
49 MODULE_LICENSE("GPL");
51 module_param(fid, int, 0444);
52 module_param(min_fsb, int, 0444);
54 MODULE_PARM_DESC(fid, "CPU multiplier to use (11.5 = 115)");
55 MODULE_PARM_DESC(min_fsb,
56 "Minimum FSB to use, if not defined: current FSB - 50");
58 #define dprintk(msg...) cpufreq_debug_printk(CPUFREQ_DEBUG_DRIVER, "cpufreq-nforce2", msg)
61 * nforce2_calc_fsb - calculate FSB
64 * Calculates FSB from PLL value
66 static int nforce2_calc_fsb(int pll)
68 unsigned char mul, div;
70 mul = (pll >> 8) & 0xff;
74 return NFORCE2_XTAL * mul / div;
80 * nforce2_calc_pll - calculate PLL value
83 * Calculate PLL value for given FSB
85 static int nforce2_calc_pll(unsigned int fsb)
87 unsigned char xmul, xdiv;
88 unsigned char mul = 0, div = 0;
91 /* Try to calculate multiplier and divider up to 4 times */
92 while (((mul == 0) || (div == 0)) && (tried <= 3)) {
93 for (xdiv = 1; xdiv <= 0x80; xdiv++)
94 for (xmul = 1; xmul <= 0xfe; xmul++)
95 if (nforce2_calc_fsb(NFORCE2_PLL(xmul, xdiv)) ==
103 if ((mul == 0) || (div == 0))
106 return NFORCE2_PLL(mul, div);
110 * nforce2_write_pll - write PLL value to chipset
113 * Writes new FSB PLL value to chipset
115 static void nforce2_write_pll(int pll)
119 /* Set the pll addr. to 0x00 */
121 pci_write_config_dword(nforce2_chipset_dev, NFORCE2_PLLADR, temp);
123 /* Now write the value in all 64 registers */
124 for (temp = 0; temp <= 0x3f; temp++) {
125 pci_write_config_dword(nforce2_chipset_dev,
126 NFORCE2_PLLREG, pll);
133 * nforce2_fsb_read - Read FSB
135 * Read FSB from chipset
136 * If bootfsb != 0, return FSB at boot-time
138 static unsigned int nforce2_fsb_read(int bootfsb)
140 struct pci_dev *nforce2_sub5;
144 /* Get chipset boot FSB from subdevice 5 (FSB at boot-time) */
145 nforce2_sub5 = pci_get_subsys(PCI_VENDOR_ID_NVIDIA,
154 pci_read_config_dword(nforce2_sub5, NFORCE2_BOOTFSB, &fsb);
157 /* Check if PLL register is already set */
158 pci_read_config_byte(nforce2_chipset_dev,
159 NFORCE2_PLLENABLE, (u8 *)&temp);
164 /* Use PLL register FSB value */
165 pci_read_config_dword(nforce2_chipset_dev,
166 NFORCE2_PLLREG, &temp);
167 fsb = nforce2_calc_fsb(temp);
173 * nforce2_set_fsb - set new FSB
178 static int nforce2_set_fsb(unsigned int fsb)
185 if ((fsb > max_fsb) || (fsb < NFORCE2_MIN_FSB)) {
186 printk(KERN_ERR "cpufreq: FSB %d is out of range!\n", fsb);
190 tfsb = nforce2_fsb_read(0);
192 printk(KERN_ERR "cpufreq: Error while reading the FSB\n");
196 /* First write? Then set actual value */
197 pci_read_config_byte(nforce2_chipset_dev,
198 NFORCE2_PLLENABLE, (u8 *)&temp);
200 pll = nforce2_calc_pll(tfsb);
205 nforce2_write_pll(pll);
208 /* Enable write access */
210 pci_write_config_byte(nforce2_chipset_dev, NFORCE2_PLLENABLE, (u8)temp);
217 while ((tfsb != fsb) && (tfsb <= max_fsb) && (tfsb >= min_fsb)) {
223 /* Calculate the PLL reg. value */
224 if ((pll = nforce2_calc_pll(tfsb)) == -1)
227 nforce2_write_pll(pll);
229 mdelay(NFORCE2_DELAY);
234 pci_write_config_byte(nforce2_chipset_dev, NFORCE2_PLLADR, (u8)temp);
240 * nforce2_get - get the CPU frequency
243 * Returns the CPU frequency
245 static unsigned int nforce2_get(unsigned int cpu)
249 return nforce2_fsb_read(0) * fid * 100;
253 * nforce2_target - set a new CPUFreq policy
254 * @policy: new policy
255 * @target_freq: the target frequency
256 * @relation: how that frequency relates to achieved frequency (CPUFREQ_RELATION_L or CPUFREQ_RELATION_H)
258 * Sets a new CPUFreq policy.
260 static int nforce2_target(struct cpufreq_policy *policy,
261 unsigned int target_freq, unsigned int relation)
263 // unsigned long flags;
264 struct cpufreq_freqs freqs;
265 unsigned int target_fsb;
267 if ((target_freq > policy->max) || (target_freq < policy->min))
270 target_fsb = target_freq / (fid * 100);
272 freqs.old = nforce2_get(policy->cpu);
273 freqs.new = target_fsb * fid * 100;
274 freqs.cpu = 0; /* Only one CPU on nForce2 plattforms */
276 if (freqs.old == freqs.new)
279 dprintk(KERN_INFO "cpufreq: Old CPU frequency %d kHz, new %d kHz\n",
280 freqs.old, freqs.new);
282 cpufreq_notify_transition(&freqs, CPUFREQ_PRECHANGE);
285 //local_irq_save(flags);
287 if (nforce2_set_fsb(target_fsb) < 0)
288 printk(KERN_ERR "cpufreq: Changing FSB to %d failed\n",
291 dprintk(KERN_INFO "cpufreq: Changed FSB successfully to %d\n",
295 //local_irq_restore(flags);
297 cpufreq_notify_transition(&freqs, CPUFREQ_POSTCHANGE);
303 * nforce2_verify - verifies a new CPUFreq policy
304 * @policy: new policy
306 static int nforce2_verify(struct cpufreq_policy *policy)
308 unsigned int fsb_pol_max;
310 fsb_pol_max = policy->max / (fid * 100);
312 if (policy->min < (fsb_pol_max * fid * 100))
313 policy->max = (fsb_pol_max + 1) * fid * 100;
315 cpufreq_verify_within_limits(policy,
316 policy->cpuinfo.min_freq,
317 policy->cpuinfo.max_freq);
321 static int nforce2_cpu_init(struct cpufreq_policy *policy)
326 /* capability check */
327 if (policy->cpu != 0)
330 /* Get current FSB */
331 fsb = nforce2_fsb_read(0);
336 /* FIX: Get FID from CPU */
340 "cpufreq: cpu_khz not set, can't calculate multiplier!\n");
344 fid = cpu_khz / (fsb * 100);
355 printk(KERN_INFO "cpufreq: FSB currently at %i MHz, FID %d.%d\n", fsb,
358 /* Set maximum FSB to FSB at boot time */
359 max_fsb = nforce2_fsb_read(1);
365 min_fsb = max_fsb - NFORCE2_SAFE_DISTANCE;
367 if (min_fsb < NFORCE2_MIN_FSB)
368 min_fsb = NFORCE2_MIN_FSB;
370 /* cpuinfo and default policy values */
371 policy->cpuinfo.min_freq = min_fsb * fid * 100;
372 policy->cpuinfo.max_freq = max_fsb * fid * 100;
373 policy->cpuinfo.transition_latency = CPUFREQ_ETERNAL;
374 policy->cur = nforce2_get(policy->cpu);
375 policy->min = policy->cpuinfo.min_freq;
376 policy->max = policy->cpuinfo.max_freq;
377 policy->governor = CPUFREQ_DEFAULT_GOVERNOR;
382 static int nforce2_cpu_exit(struct cpufreq_policy *policy)
387 static struct cpufreq_driver nforce2_driver = {
389 .verify = nforce2_verify,
390 .target = nforce2_target,
392 .init = nforce2_cpu_init,
393 .exit = nforce2_cpu_exit,
394 .owner = THIS_MODULE,
398 * nforce2_detect_chipset - detect the Southbridge which contains FSB PLL logic
400 * Detects nForce2 A2 and C1 stepping
403 static unsigned int nforce2_detect_chipset(void)
407 nforce2_chipset_dev = pci_get_subsys(PCI_VENDOR_ID_NVIDIA,
408 PCI_DEVICE_ID_NVIDIA_NFORCE2,
413 if (nforce2_chipset_dev == NULL)
416 pci_read_config_byte(nforce2_chipset_dev, PCI_REVISION_ID, &revision);
418 printk(KERN_INFO "cpufreq: Detected nForce2 chipset revision %X\n",
421 "cpufreq: FSB changing is maybe unstable and can lead to crashes and data loss.\n");
427 * nforce2_init - initializes the nForce2 CPUFreq driver
429 * Initializes the nForce2 FSB support. Returns -ENODEV on unsupported
430 * devices, -EINVAL on problems during initiatization, and zero on
433 static int __init nforce2_init(void)
435 /* TODO: do we need to detect the processor? */
438 if (nforce2_detect_chipset()) {
439 printk(KERN_ERR "cpufreq: No nForce2 chipset.\n");
443 return cpufreq_register_driver(&nforce2_driver);
447 * nforce2_exit - unregisters cpufreq module
449 * Unregisters nForce2 FSB change support.
451 static void __exit nforce2_exit(void)
453 cpufreq_unregister_driver(&nforce2_driver);
456 module_init(nforce2_init);
457 module_exit(nforce2_exit);