269 lines
6.6 KiB
C
269 lines
6.6 KiB
C
/*
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* CPPC (Collaborative Processor Performance Control) driver for
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* interfacing with the CPUfreq layer and governors. See
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* cppc_acpi.c for CPPC specific methods.
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*
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* (C) Copyright 2014, 2015 Linaro Ltd.
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* Author: Ashwin Chaugule <ashwin.chaugule@linaro.org>
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License
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* as published by the Free Software Foundation; version 2
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* of the License.
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*/
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#define pr_fmt(fmt) "CPPC Cpufreq:" fmt
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#include <linux/kernel.h>
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#include <linux/module.h>
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#include <linux/delay.h>
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#include <linux/cpu.h>
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#include <linux/cpufreq.h>
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#include <linux/dmi.h>
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#include <linux/vmalloc.h>
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#include <asm/unaligned.h>
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#include <acpi/cppc_acpi.h>
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/* Minimum struct length needed for the DMI processor entry we want */
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#define DMI_ENTRY_PROCESSOR_MIN_LENGTH 48
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/* Offest in the DMI processor structure for the max frequency */
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#define DMI_PROCESSOR_MAX_SPEED 0x14
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/*
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* These structs contain information parsed from per CPU
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* ACPI _CPC structures.
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* e.g. For each CPU the highest, lowest supported
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* performance capabilities, desired performance level
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* requested etc.
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*/
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static struct cppc_cpudata **all_cpu_data;
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/* Capture the max KHz from DMI */
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static u64 cppc_dmi_max_khz;
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/* Callback function used to retrieve the max frequency from DMI */
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static void cppc_find_dmi_mhz(const struct dmi_header *dm, void *private)
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{
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const u8 *dmi_data = (const u8 *)dm;
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u16 *mhz = (u16 *)private;
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if (dm->type == DMI_ENTRY_PROCESSOR &&
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dm->length >= DMI_ENTRY_PROCESSOR_MIN_LENGTH) {
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u16 val = (u16)get_unaligned((const u16 *)
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(dmi_data + DMI_PROCESSOR_MAX_SPEED));
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*mhz = val > *mhz ? val : *mhz;
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}
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}
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/* Look up the max frequency in DMI */
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static u64 cppc_get_dmi_max_khz(void)
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{
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u16 mhz = 0;
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dmi_walk(cppc_find_dmi_mhz, &mhz);
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/*
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* Real stupid fallback value, just in case there is no
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* actual value set.
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*/
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mhz = mhz ? mhz : 1;
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return (1000 * mhz);
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}
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static int cppc_cpufreq_set_target(struct cpufreq_policy *policy,
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unsigned int target_freq,
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unsigned int relation)
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{
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struct cppc_cpudata *cpu;
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struct cpufreq_freqs freqs;
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u32 desired_perf;
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int ret = 0;
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cpu = all_cpu_data[policy->cpu];
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desired_perf = (u64)target_freq * cpu->perf_caps.highest_perf / cppc_dmi_max_khz;
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/* Return if it is exactly the same perf */
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if (desired_perf == cpu->perf_ctrls.desired_perf)
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return ret;
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cpu->perf_ctrls.desired_perf = desired_perf;
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freqs.old = policy->cur;
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freqs.new = target_freq;
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cpufreq_freq_transition_begin(policy, &freqs);
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ret = cppc_set_perf(cpu->cpu, &cpu->perf_ctrls);
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cpufreq_freq_transition_end(policy, &freqs, ret != 0);
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if (ret)
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pr_debug("Failed to set target on CPU:%d. ret:%d\n",
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cpu->cpu, ret);
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return ret;
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}
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static int cppc_verify_policy(struct cpufreq_policy *policy)
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{
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cpufreq_verify_within_cpu_limits(policy);
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return 0;
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}
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static void cppc_cpufreq_stop_cpu(struct cpufreq_policy *policy)
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{
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int cpu_num = policy->cpu;
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struct cppc_cpudata *cpu = all_cpu_data[cpu_num];
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int ret;
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cpu->perf_ctrls.desired_perf = cpu->perf_caps.lowest_perf;
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ret = cppc_set_perf(cpu_num, &cpu->perf_ctrls);
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if (ret)
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pr_debug("Err setting perf value:%d on CPU:%d. ret:%d\n",
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cpu->perf_caps.lowest_perf, cpu_num, ret);
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}
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static int cppc_cpufreq_cpu_init(struct cpufreq_policy *policy)
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{
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struct cppc_cpudata *cpu;
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unsigned int cpu_num = policy->cpu;
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int ret = 0;
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cpu = all_cpu_data[policy->cpu];
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cpu->cpu = cpu_num;
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ret = cppc_get_perf_caps(policy->cpu, &cpu->perf_caps);
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if (ret) {
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pr_debug("Err reading CPU%d perf capabilities. ret:%d\n",
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cpu_num, ret);
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return ret;
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}
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cppc_dmi_max_khz = cppc_get_dmi_max_khz();
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/*
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* Set min to lowest nonlinear perf to avoid any efficiency penalty (see
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* Section 8.4.7.1.1.5 of ACPI 6.1 spec)
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*/
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policy->min = cpu->perf_caps.lowest_nonlinear_perf * cppc_dmi_max_khz /
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cpu->perf_caps.highest_perf;
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policy->max = cppc_dmi_max_khz;
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/*
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* Set cpuinfo.min_freq to Lowest to make the full range of performance
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* available if userspace wants to use any perf between lowest & lowest
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* nonlinear perf
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*/
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policy->cpuinfo.min_freq = cpu->perf_caps.lowest_perf * cppc_dmi_max_khz /
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cpu->perf_caps.highest_perf;
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policy->cpuinfo.max_freq = cppc_dmi_max_khz;
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policy->cpuinfo.transition_latency = cppc_get_transition_latency(cpu_num);
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policy->shared_type = cpu->shared_type;
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if (policy->shared_type == CPUFREQ_SHARED_TYPE_ANY)
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cpumask_copy(policy->cpus, cpu->shared_cpu_map);
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else if (policy->shared_type == CPUFREQ_SHARED_TYPE_ALL) {
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/* Support only SW_ANY for now. */
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pr_debug("Unsupported CPU co-ord type\n");
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return -EFAULT;
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}
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cpu->cur_policy = policy;
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/* Set policy->cur to max now. The governors will adjust later. */
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policy->cur = cppc_dmi_max_khz;
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cpu->perf_ctrls.desired_perf = cpu->perf_caps.highest_perf;
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ret = cppc_set_perf(cpu_num, &cpu->perf_ctrls);
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if (ret)
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pr_debug("Err setting perf value:%d on CPU:%d. ret:%d\n",
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cpu->perf_caps.highest_perf, cpu_num, ret);
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return ret;
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}
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static struct cpufreq_driver cppc_cpufreq_driver = {
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.flags = CPUFREQ_CONST_LOOPS,
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.verify = cppc_verify_policy,
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.target = cppc_cpufreq_set_target,
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.init = cppc_cpufreq_cpu_init,
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.stop_cpu = cppc_cpufreq_stop_cpu,
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.name = "cppc_cpufreq",
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};
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static int __init cppc_cpufreq_init(void)
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{
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int i, ret = 0;
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struct cppc_cpudata *cpu;
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if (acpi_disabled)
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return -ENODEV;
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all_cpu_data = kzalloc(sizeof(void *) * num_possible_cpus(), GFP_KERNEL);
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if (!all_cpu_data)
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return -ENOMEM;
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for_each_possible_cpu(i) {
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all_cpu_data[i] = kzalloc(sizeof(struct cppc_cpudata), GFP_KERNEL);
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if (!all_cpu_data[i])
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goto out;
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cpu = all_cpu_data[i];
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if (!zalloc_cpumask_var(&cpu->shared_cpu_map, GFP_KERNEL))
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goto out;
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}
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ret = acpi_get_psd_map(all_cpu_data);
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if (ret) {
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pr_debug("Error parsing PSD data. Aborting cpufreq registration.\n");
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goto out;
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}
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ret = cpufreq_register_driver(&cppc_cpufreq_driver);
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if (ret)
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goto out;
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return ret;
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out:
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for_each_possible_cpu(i)
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kfree(all_cpu_data[i]);
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kfree(all_cpu_data);
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return -ENODEV;
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}
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static void __exit cppc_cpufreq_exit(void)
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{
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struct cppc_cpudata *cpu;
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int i;
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cpufreq_unregister_driver(&cppc_cpufreq_driver);
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for_each_possible_cpu(i) {
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cpu = all_cpu_data[i];
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free_cpumask_var(cpu->shared_cpu_map);
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kfree(cpu);
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}
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kfree(all_cpu_data);
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}
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module_exit(cppc_cpufreq_exit);
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MODULE_AUTHOR("Ashwin Chaugule");
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MODULE_DESCRIPTION("CPUFreq driver based on the ACPI CPPC v5.0+ spec");
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MODULE_LICENSE("GPL");
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late_initcall(cppc_cpufreq_init);
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static const struct acpi_device_id cppc_acpi_ids[] = {
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{ACPI_PROCESSOR_DEVICE_HID, },
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{}
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};
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MODULE_DEVICE_TABLE(acpi, cppc_acpi_ids);
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