1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3  * (C) 2001  Dave Jones, Arjan van de ven.
4  * (C) 2002 - 2003  Dominik Brodowski <linux@brodo.de>
5  *
6  *  Based upon reverse engineered information, and on Intel documentation
7  *  for chipsets ICH2-M and ICH3-M.
8  *
9  *  Many thanks to Ducrot Bruno for finding and fixing the last
10  *  "missing link" for ICH2-M/ICH3-M support, and to Thomas Winkler
11  *  for extensive testing.
12  *
13  *  BIG FAT DISCLAIMER: Work in progress code. Possibly *dangerous*
14  */
15 
16 
17 /*********************************************************************
18  *                        SPEEDSTEP - DEFINITIONS                    *
19  *********************************************************************/
20 
21 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
22 
23 #include <linux/kernel.h>
24 #include <linux/module.h>
25 #include <linux/init.h>
26 #include <linux/cpufreq.h>
27 #include <linux/pci.h>
28 #include <linux/sched.h>
29 
30 #include <asm/cpu_device_id.h>
31 
32 #include "speedstep-lib.h"
33 
34 
35 /* speedstep_chipset:
36  *   It is necessary to know which chipset is used. As accesses to
37  * this device occur at various places in this module, we need a
38  * static struct pci_dev * pointing to that device.
39  */
40 static struct pci_dev *speedstep_chipset_dev;
41 
42 
43 /* speedstep_processor
44  */
45 static enum speedstep_processor speedstep_processor;
46 
47 static u32 pmbase;
48 
49 /*
50  *   There are only two frequency states for each processor. Values
51  * are in kHz for the time being.
52  */
53 static struct cpufreq_frequency_table speedstep_freqs[] = {
54 	{0, SPEEDSTEP_HIGH,	0},
55 	{0, SPEEDSTEP_LOW,	0},
56 	{0, 0,			CPUFREQ_TABLE_END},
57 };
58 
59 
60 /**
61  * speedstep_find_register - read the PMBASE address
62  *
63  * Returns: -ENODEV if no register could be found
64  */
65 static int speedstep_find_register(void)
66 {
67 	if (!speedstep_chipset_dev)
68 		return -ENODEV;
69 
70 	/* get PMBASE */
71 	pci_read_config_dword(speedstep_chipset_dev, 0x40, &pmbase);
72 	if (!(pmbase & 0x01)) {
73 		pr_err("could not find speedstep register\n");
74 		return -ENODEV;
75 	}
76 
77 	pmbase &= 0xFFFFFFFE;
78 	if (!pmbase) {
79 		pr_err("could not find speedstep register\n");
80 		return -ENODEV;
81 	}
82 
83 	pr_debug("pmbase is 0x%x\n", pmbase);
84 	return 0;
85 }
86 
87 /**
88  * speedstep_set_state - set the SpeedStep state
89  * @state: new processor frequency state (SPEEDSTEP_LOW or SPEEDSTEP_HIGH)
90  *
91  *   Tries to change the SpeedStep state.  Can be called from
92  *   smp_call_function_single.
93  */
94 static void speedstep_set_state(unsigned int state)
95 {
96 	u8 pm2_blk;
97 	u8 value;
98 	unsigned long flags;
99 
100 	if (state > 0x1)
101 		return;
102 
103 	/* Disable IRQs */
104 	local_irq_save(flags);
105 
106 	/* read state */
107 	value = inb(pmbase + 0x50);
108 
109 	pr_debug("read at pmbase 0x%x + 0x50 returned 0x%x\n", pmbase, value);
110 
111 	/* write new state */
112 	value &= 0xFE;
113 	value |= state;
114 
115 	pr_debug("writing 0x%x to pmbase 0x%x + 0x50\n", value, pmbase);
116 
117 	/* Disable bus master arbitration */
118 	pm2_blk = inb(pmbase + 0x20);
119 	pm2_blk |= 0x01;
120 	outb(pm2_blk, (pmbase + 0x20));
121 
122 	/* Actual transition */
123 	outb(value, (pmbase + 0x50));
124 
125 	/* Restore bus master arbitration */
126 	pm2_blk &= 0xfe;
127 	outb(pm2_blk, (pmbase + 0x20));
128 
129 	/* check if transition was successful */
130 	value = inb(pmbase + 0x50);
131 
132 	/* Enable IRQs */
133 	local_irq_restore(flags);
134 
135 	pr_debug("read at pmbase 0x%x + 0x50 returned 0x%x\n", pmbase, value);
136 
137 	if (state == (value & 0x1))
138 		pr_debug("change to %u MHz succeeded\n",
139 			speedstep_get_frequency(speedstep_processor) / 1000);
140 	else
141 		pr_err("change failed - I/O error\n");
142 
143 	return;
144 }
145 
146 /* Wrapper for smp_call_function_single. */
147 static void _speedstep_set_state(void *_state)
148 {
149 	speedstep_set_state(*(unsigned int *)_state);
150 }
151 
152 /**
153  * speedstep_activate - activate SpeedStep control in the chipset
154  *
155  *   Tries to activate the SpeedStep status and control registers.
156  * Returns -EINVAL on an unsupported chipset, and zero on success.
157  */
158 static int speedstep_activate(void)
159 {
160 	u16 value = 0;
161 
162 	if (!speedstep_chipset_dev)
163 		return -EINVAL;
164 
165 	pci_read_config_word(speedstep_chipset_dev, 0x00A0, &value);
166 	if (!(value & 0x08)) {
167 		value |= 0x08;
168 		pr_debug("activating SpeedStep (TM) registers\n");
169 		pci_write_config_word(speedstep_chipset_dev, 0x00A0, value);
170 	}
171 
172 	return 0;
173 }
174 
175 
176 /**
177  * speedstep_detect_chipset - detect the Southbridge which contains SpeedStep logic
178  *
179  *   Detects ICH2-M, ICH3-M and ICH4-M so far. The pci_dev points to
180  * the LPC bridge / PM module which contains all power-management
181  * functions. Returns the SPEEDSTEP_CHIPSET_-number for the detected
182  * chipset, or zero on failure.
183  */
184 static unsigned int speedstep_detect_chipset(void)
185 {
186 	speedstep_chipset_dev = pci_get_subsys(PCI_VENDOR_ID_INTEL,
187 			      PCI_DEVICE_ID_INTEL_82801DB_12,
188 			      PCI_ANY_ID, PCI_ANY_ID,
189 			      NULL);
190 	if (speedstep_chipset_dev)
191 		return 4; /* 4-M */
192 
193 	speedstep_chipset_dev = pci_get_subsys(PCI_VENDOR_ID_INTEL,
194 			      PCI_DEVICE_ID_INTEL_82801CA_12,
195 			      PCI_ANY_ID, PCI_ANY_ID,
196 			      NULL);
197 	if (speedstep_chipset_dev)
198 		return 3; /* 3-M */
199 
200 
201 	speedstep_chipset_dev = pci_get_subsys(PCI_VENDOR_ID_INTEL,
202 			      PCI_DEVICE_ID_INTEL_82801BA_10,
203 			      PCI_ANY_ID, PCI_ANY_ID,
204 			      NULL);
205 	if (speedstep_chipset_dev) {
206 		/* speedstep.c causes lockups on Dell Inspirons 8000 and
207 		 * 8100 which use a pretty old revision of the 82815
208 		 * host bridge. Abort on these systems.
209 		 */
210 		struct pci_dev *hostbridge;
211 
212 		hostbridge  = pci_get_subsys(PCI_VENDOR_ID_INTEL,
213 			      PCI_DEVICE_ID_INTEL_82815_MC,
214 			      PCI_ANY_ID, PCI_ANY_ID,
215 			      NULL);
216 
217 		if (!hostbridge)
218 			return 2; /* 2-M */
219 
220 		if (hostbridge->revision < 5) {
221 			pr_debug("hostbridge does not support speedstep\n");
222 			speedstep_chipset_dev = NULL;
223 			pci_dev_put(hostbridge);
224 			return 0;
225 		}
226 
227 		pci_dev_put(hostbridge);
228 		return 2; /* 2-M */
229 	}
230 
231 	return 0;
232 }
233 
234 static void get_freq_data(void *_speed)
235 {
236 	unsigned int *speed = _speed;
237 
238 	*speed = speedstep_get_frequency(speedstep_processor);
239 }
240 
241 static unsigned int speedstep_get(unsigned int cpu)
242 {
243 	unsigned int speed;
244 
245 	/* You're supposed to ensure CPU is online. */
246 	BUG_ON(smp_call_function_single(cpu, get_freq_data, &speed, 1));
247 
248 	pr_debug("detected %u kHz as current frequency\n", speed);
249 	return speed;
250 }
251 
252 /**
253  * speedstep_target - set a new CPUFreq policy
254  * @policy: new policy
255  * @index: index of target frequency
256  *
257  * Sets a new CPUFreq policy.
258  */
259 static int speedstep_target(struct cpufreq_policy *policy, unsigned int index)
260 {
261 	unsigned int policy_cpu;
262 
263 	policy_cpu = cpumask_any_and(policy->cpus, cpu_online_mask);
264 
265 	smp_call_function_single(policy_cpu, _speedstep_set_state, &index,
266 				 true);
267 
268 	return 0;
269 }
270 
271 
272 struct get_freqs {
273 	struct cpufreq_policy *policy;
274 	int ret;
275 };
276 
277 static void get_freqs_on_cpu(void *_get_freqs)
278 {
279 	struct get_freqs *get_freqs = _get_freqs;
280 
281 	get_freqs->ret =
282 		speedstep_get_freqs(speedstep_processor,
283 			    &speedstep_freqs[SPEEDSTEP_LOW].frequency,
284 			    &speedstep_freqs[SPEEDSTEP_HIGH].frequency,
285 			    &get_freqs->policy->cpuinfo.transition_latency,
286 			    &speedstep_set_state);
287 }
288 
289 static int speedstep_cpu_init(struct cpufreq_policy *policy)
290 {
291 	unsigned int policy_cpu;
292 	struct get_freqs gf;
293 
294 	/* only run on CPU to be set, or on its sibling */
295 #ifdef CONFIG_SMP
296 	cpumask_copy(policy->cpus, topology_sibling_cpumask(policy->cpu));
297 #endif
298 	policy_cpu = cpumask_any_and(policy->cpus, cpu_online_mask);
299 
300 	/* detect low and high frequency and transition latency */
301 	gf.policy = policy;
302 	smp_call_function_single(policy_cpu, get_freqs_on_cpu, &gf, 1);
303 	if (gf.ret)
304 		return gf.ret;
305 
306 	policy->freq_table = speedstep_freqs;
307 
308 	return 0;
309 }
310 
311 
312 static struct cpufreq_driver speedstep_driver = {
313 	.name	= "speedstep-ich",
314 	.verify	= cpufreq_generic_frequency_table_verify,
315 	.target_index = speedstep_target,
316 	.init	= speedstep_cpu_init,
317 	.get	= speedstep_get,
318 	.attr	= cpufreq_generic_attr,
319 };
320 
321 static const struct x86_cpu_id ss_smi_ids[] = {
322 	X86_MATCH_VENDOR_FAM_MODEL(INTEL,  6, 0x8, 0),
323 	X86_MATCH_VENDOR_FAM_MODEL(INTEL,  6, 0xb, 0),
324 	X86_MATCH_VENDOR_FAM_MODEL(INTEL, 15, 0x2, 0),
325 	{}
326 };
327 
328 /**
329  * speedstep_init - initializes the SpeedStep CPUFreq driver
330  *
331  *   Initializes the SpeedStep support. Returns -ENODEV on unsupported
332  * devices, -EINVAL on problems during initiatization, and zero on
333  * success.
334  */
335 static int __init speedstep_init(void)
336 {
337 	if (!x86_match_cpu(ss_smi_ids))
338 		return -ENODEV;
339 
340 	/* detect processor */
341 	speedstep_processor = speedstep_detect_processor();
342 	if (!speedstep_processor) {
343 		pr_debug("Intel(R) SpeedStep(TM) capable processor "
344 				"not found\n");
345 		return -ENODEV;
346 	}
347 
348 	/* detect chipset */
349 	if (!speedstep_detect_chipset()) {
350 		pr_debug("Intel(R) SpeedStep(TM) for this chipset not "
351 				"(yet) available.\n");
352 		return -ENODEV;
353 	}
354 
355 	/* activate speedstep support */
356 	if (speedstep_activate()) {
357 		pci_dev_put(speedstep_chipset_dev);
358 		return -EINVAL;
359 	}
360 
361 	if (speedstep_find_register())
362 		return -ENODEV;
363 
364 	return cpufreq_register_driver(&speedstep_driver);
365 }
366 
367 
368 /**
369  * speedstep_exit - unregisters SpeedStep support
370  *
371  *   Unregisters SpeedStep support.
372  */
373 static void __exit speedstep_exit(void)
374 {
375 	pci_dev_put(speedstep_chipset_dev);
376 	cpufreq_unregister_driver(&speedstep_driver);
377 }
378 
379 
380 MODULE_AUTHOR("Dave Jones, Dominik Brodowski <linux@brodo.de>");
381 MODULE_DESCRIPTION("Speedstep driver for Intel mobile processors on chipsets "
382 		"with ICH-M southbridges.");
383 MODULE_LICENSE("GPL");
384 
385 module_init(speedstep_init);
386 module_exit(speedstep_exit);
387