1 /*
2 * POWERNV cpufreq driver for the IBM POWER processors
3 *
4 * (C) Copyright IBM 2014
5 *
6 * Author: Vaidyanathan Srinivasan <svaidy at linux.vnet.ibm.com>
7 *
8 * This program is free software; you can redistribute it and/or modify
9 * it under the terms of the GNU General Public License as published by
10 * the Free Software Foundation; either version 2, or (at your option)
11 * any later version.
12 *
13 * This program is distributed in the hope that it will be useful,
14 * but WITHOUT ANY WARRANTY; without even the implied warranty of
15 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
16 * GNU General Public License for more details.
17 *
18 */
19
20 #define pr_fmt(fmt) "powernv-cpufreq: " fmt
21
22 #include <linux/kernel.h>
23 #include <linux/sysfs.h>
24 #include <linux/cpumask.h>
25 #include <linux/module.h>
26 #include <linux/cpufreq.h>
27 #include <linux/smp.h>
28 #include <linux/of.h>
29 #include <linux/reboot.h>
30
31 #include <asm/cputhreads.h>
32 #include <asm/firmware.h>
33 #include <asm/reg.h>
34 #include <asm/smp.h> /* Required for cpu_sibling_mask() in UP configs */
35
36 #define POWERNV_MAX_PSTATES 256
37
38 static struct cpufreq_frequency_table powernv_freqs[POWERNV_MAX_PSTATES+1];
39 static bool rebooting;
40
41 /*
42 * Note: The set of pstates consists of contiguous integers, the
43 * smallest of which is indicated by powernv_pstate_info.min, the
44 * largest of which is indicated by powernv_pstate_info.max.
45 *
46 * The nominal pstate is the highest non-turbo pstate in this
47 * platform. This is indicated by powernv_pstate_info.nominal.
48 */
49 static struct powernv_pstate_info {
50 int min;
51 int max;
52 int nominal;
53 int nr_pstates;
54 } powernv_pstate_info;
55
56 /*
57 * Initialize the freq table based on data obtained
58 * from the firmware passed via device-tree
59 */
init_powernv_pstates(void)60 static int init_powernv_pstates(void)
61 {
62 struct device_node *power_mgt;
63 int i, pstate_min, pstate_max, pstate_nominal, nr_pstates = 0;
64 const __be32 *pstate_ids, *pstate_freqs;
65 u32 len_ids, len_freqs;
66
67 power_mgt = of_find_node_by_path("/ibm,opal/power-mgt");
68 if (!power_mgt) {
69 pr_warn("power-mgt node not found\n");
70 return -ENODEV;
71 }
72
73 if (of_property_read_u32(power_mgt, "ibm,pstate-min", &pstate_min)) {
74 pr_warn("ibm,pstate-min node not found\n");
75 return -ENODEV;
76 }
77
78 if (of_property_read_u32(power_mgt, "ibm,pstate-max", &pstate_max)) {
79 pr_warn("ibm,pstate-max node not found\n");
80 return -ENODEV;
81 }
82
83 if (of_property_read_u32(power_mgt, "ibm,pstate-nominal",
84 &pstate_nominal)) {
85 pr_warn("ibm,pstate-nominal not found\n");
86 return -ENODEV;
87 }
88 pr_info("cpufreq pstate min %d nominal %d max %d\n", pstate_min,
89 pstate_nominal, pstate_max);
90
91 pstate_ids = of_get_property(power_mgt, "ibm,pstate-ids", &len_ids);
92 if (!pstate_ids) {
93 pr_warn("ibm,pstate-ids not found\n");
94 return -ENODEV;
95 }
96
97 pstate_freqs = of_get_property(power_mgt, "ibm,pstate-frequencies-mhz",
98 &len_freqs);
99 if (!pstate_freqs) {
100 pr_warn("ibm,pstate-frequencies-mhz not found\n");
101 return -ENODEV;
102 }
103
104 if (len_ids != len_freqs) {
105 pr_warn("Entries in ibm,pstate-ids and "
106 "ibm,pstate-frequencies-mhz does not match\n");
107 }
108
109 nr_pstates = min(len_ids, len_freqs) / sizeof(u32);
110 if (!nr_pstates) {
111 pr_warn("No PStates found\n");
112 return -ENODEV;
113 }
114
115 pr_debug("NR PStates %d\n", nr_pstates);
116 for (i = 0; i < nr_pstates; i++) {
117 u32 id = be32_to_cpu(pstate_ids[i]);
118 u32 freq = be32_to_cpu(pstate_freqs[i]);
119
120 pr_debug("PState id %d freq %d MHz\n", id, freq);
121 powernv_freqs[i].frequency = freq * 1000; /* kHz */
122 powernv_freqs[i].driver_data = id;
123 }
124 /* End of list marker entry */
125 powernv_freqs[i].frequency = CPUFREQ_TABLE_END;
126
127 powernv_pstate_info.min = pstate_min;
128 powernv_pstate_info.max = pstate_max;
129 powernv_pstate_info.nominal = pstate_nominal;
130 powernv_pstate_info.nr_pstates = nr_pstates;
131
132 return 0;
133 }
134
135 /* Returns the CPU frequency corresponding to the pstate_id. */
pstate_id_to_freq(int pstate_id)136 static unsigned int pstate_id_to_freq(int pstate_id)
137 {
138 int i;
139
140 i = powernv_pstate_info.max - pstate_id;
141 if (i >= powernv_pstate_info.nr_pstates || i < 0) {
142 pr_warn("PState id %d outside of PState table, "
143 "reporting nominal id %d instead\n",
144 pstate_id, powernv_pstate_info.nominal);
145 i = powernv_pstate_info.max - powernv_pstate_info.nominal;
146 }
147
148 return powernv_freqs[i].frequency;
149 }
150
151 /*
152 * cpuinfo_nominal_freq_show - Show the nominal CPU frequency as indicated by
153 * the firmware
154 */
cpuinfo_nominal_freq_show(struct cpufreq_policy * policy,char * buf)155 static ssize_t cpuinfo_nominal_freq_show(struct cpufreq_policy *policy,
156 char *buf)
157 {
158 return sprintf(buf, "%u\n",
159 pstate_id_to_freq(powernv_pstate_info.nominal));
160 }
161
162 struct freq_attr cpufreq_freq_attr_cpuinfo_nominal_freq =
163 __ATTR_RO(cpuinfo_nominal_freq);
164
165 static struct freq_attr *powernv_cpu_freq_attr[] = {
166 &cpufreq_freq_attr_scaling_available_freqs,
167 &cpufreq_freq_attr_cpuinfo_nominal_freq,
168 NULL,
169 };
170
171 /* Helper routines */
172
173 /* Access helpers to power mgt SPR */
174
get_pmspr(unsigned long sprn)175 static inline unsigned long get_pmspr(unsigned long sprn)
176 {
177 switch (sprn) {
178 case SPRN_PMCR:
179 return mfspr(SPRN_PMCR);
180
181 case SPRN_PMICR:
182 return mfspr(SPRN_PMICR);
183
184 case SPRN_PMSR:
185 return mfspr(SPRN_PMSR);
186 }
187 BUG();
188 }
189
set_pmspr(unsigned long sprn,unsigned long val)190 static inline void set_pmspr(unsigned long sprn, unsigned long val)
191 {
192 switch (sprn) {
193 case SPRN_PMCR:
194 mtspr(SPRN_PMCR, val);
195 return;
196
197 case SPRN_PMICR:
198 mtspr(SPRN_PMICR, val);
199 return;
200 }
201 BUG();
202 }
203
204 /*
205 * Use objects of this type to query/update
206 * pstates on a remote CPU via smp_call_function.
207 */
208 struct powernv_smp_call_data {
209 unsigned int freq;
210 int pstate_id;
211 };
212
213 /*
214 * powernv_read_cpu_freq: Reads the current frequency on this CPU.
215 *
216 * Called via smp_call_function.
217 *
218 * Note: The caller of the smp_call_function should pass an argument of
219 * the type 'struct powernv_smp_call_data *' along with this function.
220 *
221 * The current frequency on this CPU will be returned via
222 * ((struct powernv_smp_call_data *)arg)->freq;
223 */
powernv_read_cpu_freq(void * arg)224 static void powernv_read_cpu_freq(void *arg)
225 {
226 unsigned long pmspr_val;
227 s8 local_pstate_id;
228 struct powernv_smp_call_data *freq_data = arg;
229
230 pmspr_val = get_pmspr(SPRN_PMSR);
231
232 /*
233 * The local pstate id corresponds bits 48..55 in the PMSR.
234 * Note: Watch out for the sign!
235 */
236 local_pstate_id = (pmspr_val >> 48) & 0xFF;
237 freq_data->pstate_id = local_pstate_id;
238 freq_data->freq = pstate_id_to_freq(freq_data->pstate_id);
239
240 pr_debug("cpu %d pmsr %016lX pstate_id %d frequency %d kHz\n",
241 raw_smp_processor_id(), pmspr_val, freq_data->pstate_id,
242 freq_data->freq);
243 }
244
245 /*
246 * powernv_cpufreq_get: Returns the CPU frequency as reported by the
247 * firmware for CPU 'cpu'. This value is reported through the sysfs
248 * file cpuinfo_cur_freq.
249 */
powernv_cpufreq_get(unsigned int cpu)250 static unsigned int powernv_cpufreq_get(unsigned int cpu)
251 {
252 struct powernv_smp_call_data freq_data;
253
254 smp_call_function_any(cpu_sibling_mask(cpu), powernv_read_cpu_freq,
255 &freq_data, 1);
256
257 return freq_data.freq;
258 }
259
260 /*
261 * set_pstate: Sets the pstate on this CPU.
262 *
263 * This is called via an smp_call_function.
264 *
265 * The caller must ensure that freq_data is of the type
266 * (struct powernv_smp_call_data *) and the pstate_id which needs to be set
267 * on this CPU should be present in freq_data->pstate_id.
268 */
set_pstate(void * freq_data)269 static void set_pstate(void *freq_data)
270 {
271 unsigned long val;
272 unsigned long pstate_ul =
273 ((struct powernv_smp_call_data *) freq_data)->pstate_id;
274
275 val = get_pmspr(SPRN_PMCR);
276 val = val & 0x0000FFFFFFFFFFFFULL;
277
278 pstate_ul = pstate_ul & 0xFF;
279
280 /* Set both global(bits 56..63) and local(bits 48..55) PStates */
281 val = val | (pstate_ul << 56) | (pstate_ul << 48);
282
283 pr_debug("Setting cpu %d pmcr to %016lX\n",
284 raw_smp_processor_id(), val);
285 set_pmspr(SPRN_PMCR, val);
286 }
287
288 /*
289 * get_nominal_index: Returns the index corresponding to the nominal
290 * pstate in the cpufreq table
291 */
get_nominal_index(void)292 static inline unsigned int get_nominal_index(void)
293 {
294 return powernv_pstate_info.max - powernv_pstate_info.nominal;
295 }
296
297 /*
298 * powernv_cpufreq_target_index: Sets the frequency corresponding to
299 * the cpufreq table entry indexed by new_index on the cpus in the
300 * mask policy->cpus
301 */
powernv_cpufreq_target_index(struct cpufreq_policy * policy,unsigned int new_index)302 static int powernv_cpufreq_target_index(struct cpufreq_policy *policy,
303 unsigned int new_index)
304 {
305 struct powernv_smp_call_data freq_data;
306
307 if (unlikely(rebooting) && new_index != get_nominal_index())
308 return 0;
309
310 freq_data.pstate_id = powernv_freqs[new_index].driver_data;
311
312 /*
313 * Use smp_call_function to send IPI and execute the
314 * mtspr on target CPU. We could do that without IPI
315 * if current CPU is within policy->cpus (core)
316 */
317 smp_call_function_any(policy->cpus, set_pstate, &freq_data, 1);
318
319 return 0;
320 }
321
powernv_cpufreq_cpu_init(struct cpufreq_policy * policy)322 static int powernv_cpufreq_cpu_init(struct cpufreq_policy *policy)
323 {
324 int base, i;
325
326 base = cpu_first_thread_sibling(policy->cpu);
327
328 for (i = 0; i < threads_per_core; i++)
329 cpumask_set_cpu(base + i, policy->cpus);
330
331 return cpufreq_table_validate_and_show(policy, powernv_freqs);
332 }
333
powernv_cpufreq_reboot_notifier(struct notifier_block * nb,unsigned long action,void * unused)334 static int powernv_cpufreq_reboot_notifier(struct notifier_block *nb,
335 unsigned long action, void *unused)
336 {
337 int cpu;
338 struct cpufreq_policy cpu_policy;
339
340 rebooting = true;
341 for_each_online_cpu(cpu) {
342 cpufreq_get_policy(&cpu_policy, cpu);
343 powernv_cpufreq_target_index(&cpu_policy, get_nominal_index());
344 }
345
346 return NOTIFY_DONE;
347 }
348
349 static struct notifier_block powernv_cpufreq_reboot_nb = {
350 .notifier_call = powernv_cpufreq_reboot_notifier,
351 };
352
powernv_cpufreq_stop_cpu(struct cpufreq_policy * policy)353 static void powernv_cpufreq_stop_cpu(struct cpufreq_policy *policy)
354 {
355 struct powernv_smp_call_data freq_data;
356
357 freq_data.pstate_id = powernv_pstate_info.min;
358 smp_call_function_single(policy->cpu, set_pstate, &freq_data, 1);
359 }
360
361 static struct cpufreq_driver powernv_cpufreq_driver = {
362 .name = "powernv-cpufreq",
363 .flags = CPUFREQ_CONST_LOOPS,
364 .init = powernv_cpufreq_cpu_init,
365 .verify = cpufreq_generic_frequency_table_verify,
366 .target_index = powernv_cpufreq_target_index,
367 .get = powernv_cpufreq_get,
368 .stop_cpu = powernv_cpufreq_stop_cpu,
369 .attr = powernv_cpu_freq_attr,
370 };
371
powernv_cpufreq_init(void)372 static int __init powernv_cpufreq_init(void)
373 {
374 int rc = 0;
375
376 /* Don't probe on pseries (guest) platforms */
377 if (!firmware_has_feature(FW_FEATURE_OPALv3))
378 return -ENODEV;
379
380 /* Discover pstates from device tree and init */
381 rc = init_powernv_pstates();
382 if (rc) {
383 pr_info("powernv-cpufreq disabled. System does not support PState control\n");
384 return rc;
385 }
386
387 register_reboot_notifier(&powernv_cpufreq_reboot_nb);
388 return cpufreq_register_driver(&powernv_cpufreq_driver);
389 }
390 module_init(powernv_cpufreq_init);
391
powernv_cpufreq_exit(void)392 static void __exit powernv_cpufreq_exit(void)
393 {
394 unregister_reboot_notifier(&powernv_cpufreq_reboot_nb);
395 cpufreq_unregister_driver(&powernv_cpufreq_driver);
396 }
397 module_exit(powernv_cpufreq_exit);
398
399 MODULE_LICENSE("GPL");
400 MODULE_AUTHOR("Vaidyanathan Srinivasan <svaidy at linux.vnet.ibm.com>");
401