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Vaidyanathan Srinivasanb3d627a2014-04-01 12:43:26 +05301/*
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
30#include <asm/cputhreads.h>
Vaidyanathan Srinivasan6174bac2014-08-03 14:54:05 +053031#include <asm/firmware.h>
Vaidyanathan Srinivasanb3d627a2014-04-01 12:43:26 +053032#include <asm/reg.h>
Srivatsa S. Bhatf3cae352014-04-16 11:35:38 +053033#include <asm/smp.h> /* Required for cpu_sibling_mask() in UP configs */
Vaidyanathan Srinivasanb3d627a2014-04-01 12:43:26 +053034
35#define POWERNV_MAX_PSTATES 256
36
37static struct cpufreq_frequency_table powernv_freqs[POWERNV_MAX_PSTATES+1];
Vaidyanathan Srinivasanb3d627a2014-04-01 12:43:26 +053038
39/*
40 * Note: The set of pstates consists of contiguous integers, the
41 * smallest of which is indicated by powernv_pstate_info.min, the
42 * largest of which is indicated by powernv_pstate_info.max.
43 *
44 * The nominal pstate is the highest non-turbo pstate in this
45 * platform. This is indicated by powernv_pstate_info.nominal.
46 */
47static struct powernv_pstate_info {
48 int min;
49 int max;
50 int nominal;
51 int nr_pstates;
52} powernv_pstate_info;
53
54/*
55 * Initialize the freq table based on data obtained
56 * from the firmware passed via device-tree
57 */
58static int init_powernv_pstates(void)
59{
60 struct device_node *power_mgt;
61 int i, pstate_min, pstate_max, pstate_nominal, nr_pstates = 0;
62 const __be32 *pstate_ids, *pstate_freqs;
63 u32 len_ids, len_freqs;
64
65 power_mgt = of_find_node_by_path("/ibm,opal/power-mgt");
66 if (!power_mgt) {
67 pr_warn("power-mgt node not found\n");
68 return -ENODEV;
69 }
70
71 if (of_property_read_u32(power_mgt, "ibm,pstate-min", &pstate_min)) {
72 pr_warn("ibm,pstate-min node not found\n");
73 return -ENODEV;
74 }
75
76 if (of_property_read_u32(power_mgt, "ibm,pstate-max", &pstate_max)) {
77 pr_warn("ibm,pstate-max node not found\n");
78 return -ENODEV;
79 }
80
81 if (of_property_read_u32(power_mgt, "ibm,pstate-nominal",
82 &pstate_nominal)) {
83 pr_warn("ibm,pstate-nominal not found\n");
84 return -ENODEV;
85 }
86 pr_info("cpufreq pstate min %d nominal %d max %d\n", pstate_min,
87 pstate_nominal, pstate_max);
88
89 pstate_ids = of_get_property(power_mgt, "ibm,pstate-ids", &len_ids);
90 if (!pstate_ids) {
91 pr_warn("ibm,pstate-ids not found\n");
92 return -ENODEV;
93 }
94
95 pstate_freqs = of_get_property(power_mgt, "ibm,pstate-frequencies-mhz",
96 &len_freqs);
97 if (!pstate_freqs) {
98 pr_warn("ibm,pstate-frequencies-mhz not found\n");
99 return -ENODEV;
100 }
101
Vaidyanathan Srinivasan6174bac2014-08-03 14:54:05 +0530102 if (len_ids != len_freqs) {
103 pr_warn("Entries in ibm,pstate-ids and "
104 "ibm,pstate-frequencies-mhz does not match\n");
105 }
106
Vaidyanathan Srinivasanb3d627a2014-04-01 12:43:26 +0530107 nr_pstates = min(len_ids, len_freqs) / sizeof(u32);
108 if (!nr_pstates) {
109 pr_warn("No PStates found\n");
110 return -ENODEV;
111 }
112
113 pr_debug("NR PStates %d\n", nr_pstates);
114 for (i = 0; i < nr_pstates; i++) {
115 u32 id = be32_to_cpu(pstate_ids[i]);
116 u32 freq = be32_to_cpu(pstate_freqs[i]);
117
118 pr_debug("PState id %d freq %d MHz\n", id, freq);
119 powernv_freqs[i].frequency = freq * 1000; /* kHz */
Gautham R. Shenoy0692c692014-04-01 12:43:27 +0530120 powernv_freqs[i].driver_data = id;
Vaidyanathan Srinivasanb3d627a2014-04-01 12:43:26 +0530121 }
122 /* End of list marker entry */
123 powernv_freqs[i].frequency = CPUFREQ_TABLE_END;
124
125 powernv_pstate_info.min = pstate_min;
126 powernv_pstate_info.max = pstate_max;
127 powernv_pstate_info.nominal = pstate_nominal;
128 powernv_pstate_info.nr_pstates = nr_pstates;
129
130 return 0;
131}
132
133/* Returns the CPU frequency corresponding to the pstate_id. */
134static unsigned int pstate_id_to_freq(int pstate_id)
135{
136 int i;
137
138 i = powernv_pstate_info.max - pstate_id;
Vaidyanathan Srinivasan6174bac2014-08-03 14:54:05 +0530139 if (i >= powernv_pstate_info.nr_pstates || i < 0) {
140 pr_warn("PState id %d outside of PState table, "
141 "reporting nominal id %d instead\n",
142 pstate_id, powernv_pstate_info.nominal);
143 i = powernv_pstate_info.max - powernv_pstate_info.nominal;
144 }
Vaidyanathan Srinivasanb3d627a2014-04-01 12:43:26 +0530145
146 return powernv_freqs[i].frequency;
147}
148
149/*
150 * cpuinfo_nominal_freq_show - Show the nominal CPU frequency as indicated by
151 * the firmware
152 */
153static ssize_t cpuinfo_nominal_freq_show(struct cpufreq_policy *policy,
154 char *buf)
155{
156 return sprintf(buf, "%u\n",
157 pstate_id_to_freq(powernv_pstate_info.nominal));
158}
159
160struct freq_attr cpufreq_freq_attr_cpuinfo_nominal_freq =
161 __ATTR_RO(cpuinfo_nominal_freq);
162
163static struct freq_attr *powernv_cpu_freq_attr[] = {
164 &cpufreq_freq_attr_scaling_available_freqs,
165 &cpufreq_freq_attr_cpuinfo_nominal_freq,
166 NULL,
167};
168
169/* Helper routines */
170
171/* Access helpers to power mgt SPR */
172
173static inline unsigned long get_pmspr(unsigned long sprn)
174{
175 switch (sprn) {
176 case SPRN_PMCR:
177 return mfspr(SPRN_PMCR);
178
179 case SPRN_PMICR:
180 return mfspr(SPRN_PMICR);
181
182 case SPRN_PMSR:
183 return mfspr(SPRN_PMSR);
184 }
185 BUG();
186}
187
188static inline void set_pmspr(unsigned long sprn, unsigned long val)
189{
190 switch (sprn) {
191 case SPRN_PMCR:
192 mtspr(SPRN_PMCR, val);
193 return;
194
195 case SPRN_PMICR:
196 mtspr(SPRN_PMICR, val);
197 return;
198 }
199 BUG();
200}
201
202/*
203 * Use objects of this type to query/update
204 * pstates on a remote CPU via smp_call_function.
205 */
206struct powernv_smp_call_data {
207 unsigned int freq;
208 int pstate_id;
209};
210
211/*
212 * powernv_read_cpu_freq: Reads the current frequency on this CPU.
213 *
214 * Called via smp_call_function.
215 *
216 * Note: The caller of the smp_call_function should pass an argument of
217 * the type 'struct powernv_smp_call_data *' along with this function.
218 *
219 * The current frequency on this CPU will be returned via
220 * ((struct powernv_smp_call_data *)arg)->freq;
221 */
222static void powernv_read_cpu_freq(void *arg)
223{
224 unsigned long pmspr_val;
225 s8 local_pstate_id;
226 struct powernv_smp_call_data *freq_data = arg;
227
228 pmspr_val = get_pmspr(SPRN_PMSR);
229
230 /*
231 * The local pstate id corresponds bits 48..55 in the PMSR.
232 * Note: Watch out for the sign!
233 */
234 local_pstate_id = (pmspr_val >> 48) & 0xFF;
235 freq_data->pstate_id = local_pstate_id;
236 freq_data->freq = pstate_id_to_freq(freq_data->pstate_id);
237
238 pr_debug("cpu %d pmsr %016lX pstate_id %d frequency %d kHz\n",
239 raw_smp_processor_id(), pmspr_val, freq_data->pstate_id,
240 freq_data->freq);
241}
242
243/*
244 * powernv_cpufreq_get: Returns the CPU frequency as reported by the
245 * firmware for CPU 'cpu'. This value is reported through the sysfs
246 * file cpuinfo_cur_freq.
247 */
Brian Norris60d1ea42014-05-11 00:51:20 -0700248static unsigned int powernv_cpufreq_get(unsigned int cpu)
Vaidyanathan Srinivasanb3d627a2014-04-01 12:43:26 +0530249{
250 struct powernv_smp_call_data freq_data;
251
252 smp_call_function_any(cpu_sibling_mask(cpu), powernv_read_cpu_freq,
253 &freq_data, 1);
254
255 return freq_data.freq;
256}
257
258/*
259 * set_pstate: Sets the pstate on this CPU.
260 *
261 * This is called via an smp_call_function.
262 *
263 * The caller must ensure that freq_data is of the type
264 * (struct powernv_smp_call_data *) and the pstate_id which needs to be set
265 * on this CPU should be present in freq_data->pstate_id.
266 */
267static void set_pstate(void *freq_data)
268{
269 unsigned long val;
270 unsigned long pstate_ul =
271 ((struct powernv_smp_call_data *) freq_data)->pstate_id;
272
273 val = get_pmspr(SPRN_PMCR);
274 val = val & 0x0000FFFFFFFFFFFFULL;
275
276 pstate_ul = pstate_ul & 0xFF;
277
278 /* Set both global(bits 56..63) and local(bits 48..55) PStates */
279 val = val | (pstate_ul << 56) | (pstate_ul << 48);
280
281 pr_debug("Setting cpu %d pmcr to %016lX\n",
282 raw_smp_processor_id(), val);
283 set_pmspr(SPRN_PMCR, val);
284}
285
286/*
287 * powernv_cpufreq_target_index: Sets the frequency corresponding to
288 * the cpufreq table entry indexed by new_index on the cpus in the
289 * mask policy->cpus
290 */
291static int powernv_cpufreq_target_index(struct cpufreq_policy *policy,
292 unsigned int new_index)
293{
294 struct powernv_smp_call_data freq_data;
295
Gautham R. Shenoy0692c692014-04-01 12:43:27 +0530296 freq_data.pstate_id = powernv_freqs[new_index].driver_data;
Vaidyanathan Srinivasanb3d627a2014-04-01 12:43:26 +0530297
298 /*
299 * Use smp_call_function to send IPI and execute the
300 * mtspr on target CPU. We could do that without IPI
301 * if current CPU is within policy->cpus (core)
302 */
303 smp_call_function_any(policy->cpus, set_pstate, &freq_data, 1);
304
305 return 0;
306}
307
308static int powernv_cpufreq_cpu_init(struct cpufreq_policy *policy)
309{
310 int base, i;
311
312 base = cpu_first_thread_sibling(policy->cpu);
313
314 for (i = 0; i < threads_per_core; i++)
315 cpumask_set_cpu(base + i, policy->cpus);
316
317 return cpufreq_table_validate_and_show(policy, powernv_freqs);
318}
319
Preeti U Murthyb1203392014-09-29 15:47:53 +0200320static void powernv_cpufreq_stop_cpu(struct cpufreq_policy *policy)
321{
322 struct powernv_smp_call_data freq_data;
323
324 freq_data.pstate_id = powernv_pstate_info.min;
325 smp_call_function_single(policy->cpu, set_pstate, &freq_data, 1);
326}
327
Vaidyanathan Srinivasanb3d627a2014-04-01 12:43:26 +0530328static struct cpufreq_driver powernv_cpufreq_driver = {
329 .name = "powernv-cpufreq",
330 .flags = CPUFREQ_CONST_LOOPS,
331 .init = powernv_cpufreq_cpu_init,
332 .verify = cpufreq_generic_frequency_table_verify,
333 .target_index = powernv_cpufreq_target_index,
334 .get = powernv_cpufreq_get,
Preeti U Murthyb1203392014-09-29 15:47:53 +0200335 .stop_cpu = powernv_cpufreq_stop_cpu,
Vaidyanathan Srinivasanb3d627a2014-04-01 12:43:26 +0530336 .attr = powernv_cpu_freq_attr,
337};
338
339static int __init powernv_cpufreq_init(void)
340{
341 int rc = 0;
342
Vaidyanathan Srinivasan6174bac2014-08-03 14:54:05 +0530343 /* Don't probe on pseries (guest) platforms */
344 if (!firmware_has_feature(FW_FEATURE_OPALv3))
345 return -ENODEV;
346
Vaidyanathan Srinivasanb3d627a2014-04-01 12:43:26 +0530347 /* Discover pstates from device tree and init */
348 rc = init_powernv_pstates();
349 if (rc) {
350 pr_info("powernv-cpufreq disabled. System does not support PState control\n");
351 return rc;
352 }
353
354 return cpufreq_register_driver(&powernv_cpufreq_driver);
355}
356module_init(powernv_cpufreq_init);
357
358static void __exit powernv_cpufreq_exit(void)
359{
360 cpufreq_unregister_driver(&powernv_cpufreq_driver);
361}
362module_exit(powernv_cpufreq_exit);
363
364MODULE_LICENSE("GPL");
365MODULE_AUTHOR("Vaidyanathan Srinivasan <svaidy at linux.vnet.ibm.com>");