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![Viresh Kumar](/assets/img/avatar_default.png)
During cpufreq driver's registration, if the ->init() callback for all the CPUs fail then there is not much point in keeping the driver around as it will only account for more of unnecessary noise, for example cpufreq core will try to suspend/resume the driver which never got registered properly. The removal of such a driver is avoided if the driver carries the CPUFREQ_STICKY flag. This was added way back [1] in 2004 and perhaps no one should ever need it now. A lot of drivers do set this flag, probably because they just copied it from other drivers. This was added earlier for some platforms [2] because their cpufreq drivers were getting registered before the CPUs were registered with subsys framework. And hence they used to fail. The same isn't true anymore though. The current code flow in the kernel is: start_kernel() -> kernel_init() -> kernel_init_freeable() -> do_basic_setup() -> driver_init() -> cpu_dev_init() -> subsys_system_register() //For CPUs -> do_initcalls() -> cpufreq_register_driver() Clearly, the CPUs will always get registered with subsys framework before any cpufreq driver can get probed. Remove the flag and update the relevant drivers. Link: https://git.kernel.org/pub/scm/linux/kernel/git/tglx/history.git/commit/include/linux/cpufreq.h?id=7cc9f0d9a1ab04cedc60d64fd8dcf7df224a3b4d # [1] Link: https://git.kernel.org/pub/scm/linux/kernel/git/tglx/history.git/commit/arch/arm/mach-sa1100/cpu-sa1100.c?id=f59d3bbe35f6268d729f51be82af8325d62f20f5 # [2] Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
278 lines
6.7 KiB
C
278 lines
6.7 KiB
C
// SPDX-License-Identifier: GPL-2.0
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/*
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* System Control and Power Interface (SCMI) based CPUFreq Interface driver
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*
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* Copyright (C) 2018 ARM Ltd.
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* Sudeep Holla <sudeep.holla@arm.com>
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*/
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#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
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#include <linux/clk-provider.h>
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#include <linux/cpu.h>
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#include <linux/cpufreq.h>
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#include <linux/cpumask.h>
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#include <linux/energy_model.h>
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#include <linux/export.h>
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#include <linux/module.h>
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#include <linux/pm_opp.h>
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#include <linux/slab.h>
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#include <linux/scmi_protocol.h>
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#include <linux/types.h>
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struct scmi_data {
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int domain_id;
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struct device *cpu_dev;
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};
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static const struct scmi_handle *handle;
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static unsigned int scmi_cpufreq_get_rate(unsigned int cpu)
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{
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struct cpufreq_policy *policy = cpufreq_cpu_get_raw(cpu);
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const struct scmi_perf_ops *perf_ops = handle->perf_ops;
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struct scmi_data *priv = policy->driver_data;
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unsigned long rate;
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int ret;
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ret = perf_ops->freq_get(handle, priv->domain_id, &rate, false);
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if (ret)
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return 0;
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return rate / 1000;
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}
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/*
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* perf_ops->freq_set is not a synchronous, the actual OPP change will
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* happen asynchronously and can get notified if the events are
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* subscribed for by the SCMI firmware
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*/
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static int
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scmi_cpufreq_set_target(struct cpufreq_policy *policy, unsigned int index)
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{
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struct scmi_data *priv = policy->driver_data;
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const struct scmi_perf_ops *perf_ops = handle->perf_ops;
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u64 freq = policy->freq_table[index].frequency;
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return perf_ops->freq_set(handle, priv->domain_id, freq * 1000, false);
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}
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static unsigned int scmi_cpufreq_fast_switch(struct cpufreq_policy *policy,
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unsigned int target_freq)
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{
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struct scmi_data *priv = policy->driver_data;
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const struct scmi_perf_ops *perf_ops = handle->perf_ops;
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if (!perf_ops->freq_set(handle, priv->domain_id,
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target_freq * 1000, true))
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return target_freq;
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return 0;
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}
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static int
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scmi_get_sharing_cpus(struct device *cpu_dev, struct cpumask *cpumask)
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{
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int cpu, domain, tdomain;
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struct device *tcpu_dev;
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domain = handle->perf_ops->device_domain_id(cpu_dev);
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if (domain < 0)
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return domain;
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for_each_possible_cpu(cpu) {
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if (cpu == cpu_dev->id)
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continue;
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tcpu_dev = get_cpu_device(cpu);
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if (!tcpu_dev)
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continue;
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tdomain = handle->perf_ops->device_domain_id(tcpu_dev);
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if (tdomain == domain)
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cpumask_set_cpu(cpu, cpumask);
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}
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return 0;
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}
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static int __maybe_unused
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scmi_get_cpu_power(unsigned long *power, unsigned long *KHz,
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struct device *cpu_dev)
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{
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unsigned long Hz;
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int ret, domain;
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domain = handle->perf_ops->device_domain_id(cpu_dev);
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if (domain < 0)
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return domain;
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/* Get the power cost of the performance domain. */
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Hz = *KHz * 1000;
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ret = handle->perf_ops->est_power_get(handle, domain, &Hz, power);
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if (ret)
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return ret;
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/* The EM framework specifies the frequency in KHz. */
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*KHz = Hz / 1000;
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return 0;
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}
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static int scmi_cpufreq_init(struct cpufreq_policy *policy)
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{
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int ret, nr_opp;
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unsigned int latency;
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struct device *cpu_dev;
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struct scmi_data *priv;
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struct cpufreq_frequency_table *freq_table;
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struct em_data_callback em_cb = EM_DATA_CB(scmi_get_cpu_power);
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bool power_scale_mw;
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cpu_dev = get_cpu_device(policy->cpu);
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if (!cpu_dev) {
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pr_err("failed to get cpu%d device\n", policy->cpu);
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return -ENODEV;
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}
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ret = handle->perf_ops->device_opps_add(handle, cpu_dev);
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if (ret) {
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dev_warn(cpu_dev, "failed to add opps to the device\n");
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return ret;
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}
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ret = scmi_get_sharing_cpus(cpu_dev, policy->cpus);
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if (ret) {
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dev_warn(cpu_dev, "failed to get sharing cpumask\n");
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return ret;
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}
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ret = dev_pm_opp_set_sharing_cpus(cpu_dev, policy->cpus);
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if (ret) {
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dev_err(cpu_dev, "%s: failed to mark OPPs as shared: %d\n",
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__func__, ret);
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return ret;
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}
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nr_opp = dev_pm_opp_get_opp_count(cpu_dev);
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if (nr_opp <= 0) {
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dev_dbg(cpu_dev, "OPP table is not ready, deferring probe\n");
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ret = -EPROBE_DEFER;
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goto out_free_opp;
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}
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priv = kzalloc(sizeof(*priv), GFP_KERNEL);
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if (!priv) {
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ret = -ENOMEM;
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goto out_free_opp;
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}
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ret = dev_pm_opp_init_cpufreq_table(cpu_dev, &freq_table);
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if (ret) {
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dev_err(cpu_dev, "failed to init cpufreq table: %d\n", ret);
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goto out_free_priv;
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}
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priv->cpu_dev = cpu_dev;
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priv->domain_id = handle->perf_ops->device_domain_id(cpu_dev);
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policy->driver_data = priv;
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policy->freq_table = freq_table;
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/* SCMI allows DVFS request for any domain from any CPU */
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policy->dvfs_possible_from_any_cpu = true;
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latency = handle->perf_ops->transition_latency_get(handle, cpu_dev);
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if (!latency)
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latency = CPUFREQ_ETERNAL;
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policy->cpuinfo.transition_latency = latency;
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policy->fast_switch_possible =
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handle->perf_ops->fast_switch_possible(handle, cpu_dev);
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power_scale_mw = handle->perf_ops->power_scale_mw_get(handle);
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em_dev_register_perf_domain(cpu_dev, nr_opp, &em_cb, policy->cpus,
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power_scale_mw);
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return 0;
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out_free_priv:
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kfree(priv);
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out_free_opp:
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dev_pm_opp_remove_all_dynamic(cpu_dev);
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return ret;
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}
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static int scmi_cpufreq_exit(struct cpufreq_policy *policy)
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{
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struct scmi_data *priv = policy->driver_data;
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dev_pm_opp_free_cpufreq_table(priv->cpu_dev, &policy->freq_table);
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dev_pm_opp_remove_all_dynamic(priv->cpu_dev);
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kfree(priv);
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return 0;
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}
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static struct cpufreq_driver scmi_cpufreq_driver = {
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.name = "scmi",
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.flags = CPUFREQ_HAVE_GOVERNOR_PER_POLICY |
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CPUFREQ_NEED_INITIAL_FREQ_CHECK |
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CPUFREQ_IS_COOLING_DEV,
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.verify = cpufreq_generic_frequency_table_verify,
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.attr = cpufreq_generic_attr,
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.target_index = scmi_cpufreq_set_target,
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.fast_switch = scmi_cpufreq_fast_switch,
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.get = scmi_cpufreq_get_rate,
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.init = scmi_cpufreq_init,
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.exit = scmi_cpufreq_exit,
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};
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static int scmi_cpufreq_probe(struct scmi_device *sdev)
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{
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int ret;
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struct device *dev = &sdev->dev;
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handle = sdev->handle;
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if (!handle || !handle->perf_ops)
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return -ENODEV;
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#ifdef CONFIG_COMMON_CLK
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/* dummy clock provider as needed by OPP if clocks property is used */
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if (of_find_property(dev->of_node, "#clock-cells", NULL))
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devm_of_clk_add_hw_provider(dev, of_clk_hw_simple_get, NULL);
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#endif
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ret = cpufreq_register_driver(&scmi_cpufreq_driver);
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if (ret) {
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dev_err(dev, "%s: registering cpufreq failed, err: %d\n",
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__func__, ret);
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}
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return ret;
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}
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static void scmi_cpufreq_remove(struct scmi_device *sdev)
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{
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cpufreq_unregister_driver(&scmi_cpufreq_driver);
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}
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static const struct scmi_device_id scmi_id_table[] = {
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{ SCMI_PROTOCOL_PERF, "cpufreq" },
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{ },
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};
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MODULE_DEVICE_TABLE(scmi, scmi_id_table);
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static struct scmi_driver scmi_cpufreq_drv = {
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.name = "scmi-cpufreq",
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.probe = scmi_cpufreq_probe,
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.remove = scmi_cpufreq_remove,
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.id_table = scmi_id_table,
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};
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module_scmi_driver(scmi_cpufreq_drv);
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MODULE_AUTHOR("Sudeep Holla <sudeep.holla@arm.com>");
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MODULE_DESCRIPTION("ARM SCMI CPUFreq interface driver");
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MODULE_LICENSE("GPL v2");
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