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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>
31#include <asm/reg.h>
Srivatsa S. Bhatf3cae352014-04-16 11:35:38 +053032#include <asm/smp.h> /* Required for cpu_sibling_mask() in UP configs */
Vaidyanathan Srinivasanb3d627a2014-04-01 12:43:26 +053033
34#define POWERNV_MAX_PSTATES 256
35
36static struct cpufreq_frequency_table powernv_freqs[POWERNV_MAX_PSTATES+1];
Vaidyanathan Srinivasanb3d627a2014-04-01 12:43:26 +053037
38/*
39 * Note: The set of pstates consists of contiguous integers, the
40 * smallest of which is indicated by powernv_pstate_info.min, the
41 * largest of which is indicated by powernv_pstate_info.max.
42 *
43 * The nominal pstate is the highest non-turbo pstate in this
44 * platform. This is indicated by powernv_pstate_info.nominal.
45 */
46static struct powernv_pstate_info {
47 int min;
48 int max;
49 int nominal;
50 int nr_pstates;
51} powernv_pstate_info;
52
53/*
54 * Initialize the freq table based on data obtained
55 * from the firmware passed via device-tree
56 */
57static int init_powernv_pstates(void)
58{
59 struct device_node *power_mgt;
60 int i, pstate_min, pstate_max, pstate_nominal, nr_pstates = 0;
61 const __be32 *pstate_ids, *pstate_freqs;
62 u32 len_ids, len_freqs;
63
64 power_mgt = of_find_node_by_path("/ibm,opal/power-mgt");
65 if (!power_mgt) {
66 pr_warn("power-mgt node not found\n");
67 return -ENODEV;
68 }
69
70 if (of_property_read_u32(power_mgt, "ibm,pstate-min", &pstate_min)) {
71 pr_warn("ibm,pstate-min node not found\n");
72 return -ENODEV;
73 }
74
75 if (of_property_read_u32(power_mgt, "ibm,pstate-max", &pstate_max)) {
76 pr_warn("ibm,pstate-max node not found\n");
77 return -ENODEV;
78 }
79
80 if (of_property_read_u32(power_mgt, "ibm,pstate-nominal",
81 &pstate_nominal)) {
82 pr_warn("ibm,pstate-nominal not found\n");
83 return -ENODEV;
84 }
85 pr_info("cpufreq pstate min %d nominal %d max %d\n", pstate_min,
86 pstate_nominal, pstate_max);
87
88 pstate_ids = of_get_property(power_mgt, "ibm,pstate-ids", &len_ids);
89 if (!pstate_ids) {
90 pr_warn("ibm,pstate-ids not found\n");
91 return -ENODEV;
92 }
93
94 pstate_freqs = of_get_property(power_mgt, "ibm,pstate-frequencies-mhz",
95 &len_freqs);
96 if (!pstate_freqs) {
97 pr_warn("ibm,pstate-frequencies-mhz not found\n");
98 return -ENODEV;
99 }
100
101 WARN_ON(len_ids != len_freqs);
102 nr_pstates = min(len_ids, len_freqs) / sizeof(u32);
103 if (!nr_pstates) {
104 pr_warn("No PStates found\n");
105 return -ENODEV;
106 }
107
108 pr_debug("NR PStates %d\n", nr_pstates);
109 for (i = 0; i < nr_pstates; i++) {
110 u32 id = be32_to_cpu(pstate_ids[i]);
111 u32 freq = be32_to_cpu(pstate_freqs[i]);
112
113 pr_debug("PState id %d freq %d MHz\n", id, freq);
114 powernv_freqs[i].frequency = freq * 1000; /* kHz */
Gautham R. Shenoy0692c692014-04-01 12:43:27 +0530115 powernv_freqs[i].driver_data = id;
Vaidyanathan Srinivasanb3d627a2014-04-01 12:43:26 +0530116 }
117 /* End of list marker entry */
118 powernv_freqs[i].frequency = CPUFREQ_TABLE_END;
119
120 powernv_pstate_info.min = pstate_min;
121 powernv_pstate_info.max = pstate_max;
122 powernv_pstate_info.nominal = pstate_nominal;
123 powernv_pstate_info.nr_pstates = nr_pstates;
124
125 return 0;
126}
127
128/* Returns the CPU frequency corresponding to the pstate_id. */
129static unsigned int pstate_id_to_freq(int pstate_id)
130{
131 int i;
132
133 i = powernv_pstate_info.max - pstate_id;
134 BUG_ON(i >= powernv_pstate_info.nr_pstates || i < 0);
135
136 return powernv_freqs[i].frequency;
137}
138
139/*
140 * cpuinfo_nominal_freq_show - Show the nominal CPU frequency as indicated by
141 * the firmware
142 */
143static ssize_t cpuinfo_nominal_freq_show(struct cpufreq_policy *policy,
144 char *buf)
145{
146 return sprintf(buf, "%u\n",
147 pstate_id_to_freq(powernv_pstate_info.nominal));
148}
149
150struct freq_attr cpufreq_freq_attr_cpuinfo_nominal_freq =
151 __ATTR_RO(cpuinfo_nominal_freq);
152
153static struct freq_attr *powernv_cpu_freq_attr[] = {
154 &cpufreq_freq_attr_scaling_available_freqs,
155 &cpufreq_freq_attr_cpuinfo_nominal_freq,
156 NULL,
157};
158
159/* Helper routines */
160
161/* Access helpers to power mgt SPR */
162
163static inline unsigned long get_pmspr(unsigned long sprn)
164{
165 switch (sprn) {
166 case SPRN_PMCR:
167 return mfspr(SPRN_PMCR);
168
169 case SPRN_PMICR:
170 return mfspr(SPRN_PMICR);
171
172 case SPRN_PMSR:
173 return mfspr(SPRN_PMSR);
174 }
175 BUG();
176}
177
178static inline void set_pmspr(unsigned long sprn, unsigned long val)
179{
180 switch (sprn) {
181 case SPRN_PMCR:
182 mtspr(SPRN_PMCR, val);
183 return;
184
185 case SPRN_PMICR:
186 mtspr(SPRN_PMICR, val);
187 return;
188 }
189 BUG();
190}
191
192/*
193 * Use objects of this type to query/update
194 * pstates on a remote CPU via smp_call_function.
195 */
196struct powernv_smp_call_data {
197 unsigned int freq;
198 int pstate_id;
199};
200
201/*
202 * powernv_read_cpu_freq: Reads the current frequency on this CPU.
203 *
204 * Called via smp_call_function.
205 *
206 * Note: The caller of the smp_call_function should pass an argument of
207 * the type 'struct powernv_smp_call_data *' along with this function.
208 *
209 * The current frequency on this CPU will be returned via
210 * ((struct powernv_smp_call_data *)arg)->freq;
211 */
212static void powernv_read_cpu_freq(void *arg)
213{
214 unsigned long pmspr_val;
215 s8 local_pstate_id;
216 struct powernv_smp_call_data *freq_data = arg;
217
218 pmspr_val = get_pmspr(SPRN_PMSR);
219
220 /*
221 * The local pstate id corresponds bits 48..55 in the PMSR.
222 * Note: Watch out for the sign!
223 */
224 local_pstate_id = (pmspr_val >> 48) & 0xFF;
225 freq_data->pstate_id = local_pstate_id;
226 freq_data->freq = pstate_id_to_freq(freq_data->pstate_id);
227
228 pr_debug("cpu %d pmsr %016lX pstate_id %d frequency %d kHz\n",
229 raw_smp_processor_id(), pmspr_val, freq_data->pstate_id,
230 freq_data->freq);
231}
232
233/*
234 * powernv_cpufreq_get: Returns the CPU frequency as reported by the
235 * firmware for CPU 'cpu'. This value is reported through the sysfs
236 * file cpuinfo_cur_freq.
237 */
Brian Norris60d1ea42014-05-11 00:51:20 -0700238static unsigned int powernv_cpufreq_get(unsigned int cpu)
Vaidyanathan Srinivasanb3d627a2014-04-01 12:43:26 +0530239{
240 struct powernv_smp_call_data freq_data;
241
242 smp_call_function_any(cpu_sibling_mask(cpu), powernv_read_cpu_freq,
243 &freq_data, 1);
244
245 return freq_data.freq;
246}
247
248/*
249 * set_pstate: Sets the pstate on this CPU.
250 *
251 * This is called via an smp_call_function.
252 *
253 * The caller must ensure that freq_data is of the type
254 * (struct powernv_smp_call_data *) and the pstate_id which needs to be set
255 * on this CPU should be present in freq_data->pstate_id.
256 */
257static void set_pstate(void *freq_data)
258{
259 unsigned long val;
260 unsigned long pstate_ul =
261 ((struct powernv_smp_call_data *) freq_data)->pstate_id;
262
263 val = get_pmspr(SPRN_PMCR);
264 val = val & 0x0000FFFFFFFFFFFFULL;
265
266 pstate_ul = pstate_ul & 0xFF;
267
268 /* Set both global(bits 56..63) and local(bits 48..55) PStates */
269 val = val | (pstate_ul << 56) | (pstate_ul << 48);
270
271 pr_debug("Setting cpu %d pmcr to %016lX\n",
272 raw_smp_processor_id(), val);
273 set_pmspr(SPRN_PMCR, val);
274}
275
276/*
277 * powernv_cpufreq_target_index: Sets the frequency corresponding to
278 * the cpufreq table entry indexed by new_index on the cpus in the
279 * mask policy->cpus
280 */
281static int powernv_cpufreq_target_index(struct cpufreq_policy *policy,
282 unsigned int new_index)
283{
284 struct powernv_smp_call_data freq_data;
285
Gautham R. Shenoy0692c692014-04-01 12:43:27 +0530286 freq_data.pstate_id = powernv_freqs[new_index].driver_data;
Vaidyanathan Srinivasanb3d627a2014-04-01 12:43:26 +0530287
288 /*
289 * Use smp_call_function to send IPI and execute the
290 * mtspr on target CPU. We could do that without IPI
291 * if current CPU is within policy->cpus (core)
292 */
293 smp_call_function_any(policy->cpus, set_pstate, &freq_data, 1);
294
295 return 0;
296}
297
298static int powernv_cpufreq_cpu_init(struct cpufreq_policy *policy)
299{
300 int base, i;
301
302 base = cpu_first_thread_sibling(policy->cpu);
303
304 for (i = 0; i < threads_per_core; i++)
305 cpumask_set_cpu(base + i, policy->cpus);
306
307 return cpufreq_table_validate_and_show(policy, powernv_freqs);
308}
309
310static struct cpufreq_driver powernv_cpufreq_driver = {
311 .name = "powernv-cpufreq",
312 .flags = CPUFREQ_CONST_LOOPS,
313 .init = powernv_cpufreq_cpu_init,
314 .verify = cpufreq_generic_frequency_table_verify,
315 .target_index = powernv_cpufreq_target_index,
316 .get = powernv_cpufreq_get,
317 .attr = powernv_cpu_freq_attr,
318};
319
320static int __init powernv_cpufreq_init(void)
321{
322 int rc = 0;
323
324 /* Discover pstates from device tree and init */
325 rc = init_powernv_pstates();
326 if (rc) {
327 pr_info("powernv-cpufreq disabled. System does not support PState control\n");
328 return rc;
329 }
330
331 return cpufreq_register_driver(&powernv_cpufreq_driver);
332}
333module_init(powernv_cpufreq_init);
334
335static void __exit powernv_cpufreq_exit(void)
336{
337 cpufreq_unregister_driver(&powernv_cpufreq_driver);
338}
339module_exit(powernv_cpufreq_exit);
340
341MODULE_LICENSE("GPL");
342MODULE_AUTHOR("Vaidyanathan Srinivasan <svaidy at linux.vnet.ibm.com>");