174 lines · c
1// SPDX-License-Identifier: GPL-2.0-or-later2/*3 * cpufreq driver for the cell processor4 *5 * (C) Copyright IBM Deutschland Entwicklung GmbH 2005-20076 *7 * Author: Christian Krafft <krafft@de.ibm.com>8 */9 10#include <linux/cpufreq.h>11#include <linux/module.h>12#include <linux/of.h>13 14#include <asm/machdep.h>15#include <asm/cell-regs.h>16 17#include "ppc_cbe_cpufreq.h"18 19/* the CBE supports an 8 step frequency scaling */20static struct cpufreq_frequency_table cbe_freqs[] = {21 {0, 1, 0},22 {0, 2, 0},23 {0, 3, 0},24 {0, 4, 0},25 {0, 5, 0},26 {0, 6, 0},27 {0, 8, 0},28 {0, 10, 0},29 {0, 0, CPUFREQ_TABLE_END},30};31 32/*33 * hardware specific functions34 */35 36static int set_pmode(unsigned int cpu, unsigned int slow_mode)37{38 int rc;39 40 if (cbe_cpufreq_has_pmi)41 rc = cbe_cpufreq_set_pmode_pmi(cpu, slow_mode);42 else43 rc = cbe_cpufreq_set_pmode(cpu, slow_mode);44 45 pr_debug("register contains slow mode %d\n", cbe_cpufreq_get_pmode(cpu));46 47 return rc;48}49 50/*51 * cpufreq functions52 */53 54static int cbe_cpufreq_cpu_init(struct cpufreq_policy *policy)55{56 struct cpufreq_frequency_table *pos;57 const u32 *max_freqp;58 u32 max_freq;59 int cur_pmode;60 struct device_node *cpu;61 62 cpu = of_get_cpu_node(policy->cpu, NULL);63 64 if (!cpu)65 return -ENODEV;66 67 pr_debug("init cpufreq on CPU %d\n", policy->cpu);68 69 /*70 * Let's check we can actually get to the CELL regs71 */72 if (!cbe_get_cpu_pmd_regs(policy->cpu) ||73 !cbe_get_cpu_mic_tm_regs(policy->cpu)) {74 pr_info("invalid CBE regs pointers for cpufreq\n");75 of_node_put(cpu);76 return -EINVAL;77 }78 79 max_freqp = of_get_property(cpu, "clock-frequency", NULL);80 81 of_node_put(cpu);82 83 if (!max_freqp)84 return -EINVAL;85 86 /* we need the freq in kHz */87 max_freq = *max_freqp / 1000;88 89 pr_debug("max clock-frequency is at %u kHz\n", max_freq);90 pr_debug("initializing frequency table\n");91 92 /* initialize frequency table */93 cpufreq_for_each_entry(pos, cbe_freqs) {94 pos->frequency = max_freq / pos->driver_data;95 pr_debug("%d: %d\n", (int)(pos - cbe_freqs), pos->frequency);96 }97 98 /* if DEBUG is enabled set_pmode() measures the latency99 * of a transition */100 policy->cpuinfo.transition_latency = 25000;101 102 cur_pmode = cbe_cpufreq_get_pmode(policy->cpu);103 pr_debug("current pmode is at %d\n",cur_pmode);104 105 policy->cur = cbe_freqs[cur_pmode].frequency;106 107#ifdef CONFIG_SMP108 cpumask_copy(policy->cpus, cpu_sibling_mask(policy->cpu));109#endif110 111 policy->freq_table = cbe_freqs;112 cbe_cpufreq_pmi_policy_init(policy);113 return 0;114}115 116static void cbe_cpufreq_cpu_exit(struct cpufreq_policy *policy)117{118 cbe_cpufreq_pmi_policy_exit(policy);119}120 121static int cbe_cpufreq_target(struct cpufreq_policy *policy,122 unsigned int cbe_pmode_new)123{124 pr_debug("setting frequency for cpu %d to %d kHz, " \125 "1/%d of max frequency\n",126 policy->cpu,127 cbe_freqs[cbe_pmode_new].frequency,128 cbe_freqs[cbe_pmode_new].driver_data);129 130 return set_pmode(policy->cpu, cbe_pmode_new);131}132 133static struct cpufreq_driver cbe_cpufreq_driver = {134 .verify = cpufreq_generic_frequency_table_verify,135 .target_index = cbe_cpufreq_target,136 .init = cbe_cpufreq_cpu_init,137 .exit = cbe_cpufreq_cpu_exit,138 .name = "cbe-cpufreq",139 .flags = CPUFREQ_CONST_LOOPS,140};141 142/*143 * module init and destoy144 */145 146static int __init cbe_cpufreq_init(void)147{148 int ret;149 150 if (!machine_is(cell))151 return -ENODEV;152 153 cbe_cpufreq_pmi_init();154 155 ret = cpufreq_register_driver(&cbe_cpufreq_driver);156 if (ret)157 cbe_cpufreq_pmi_exit();158 159 return ret;160}161 162static void __exit cbe_cpufreq_exit(void)163{164 cpufreq_unregister_driver(&cbe_cpufreq_driver);165 cbe_cpufreq_pmi_exit();166}167 168module_init(cbe_cpufreq_init);169module_exit(cbe_cpufreq_exit);170 171MODULE_DESCRIPTION("cpufreq driver for Cell BE processors");172MODULE_LICENSE("GPL");173MODULE_AUTHOR("Christian Krafft <krafft@de.ibm.com>");174