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Diffstat (limited to 'drivers/cpufreq/scmi-cpufreq.c')
-rw-r--r--drivers/cpufreq/scmi-cpufreq.c350
1 files changed, 350 insertions, 0 deletions
diff --git a/drivers/cpufreq/scmi-cpufreq.c b/drivers/cpufreq/scmi-cpufreq.c
new file mode 100644
index 0000000000..028df8a5f5
--- /dev/null
+++ b/drivers/cpufreq/scmi-cpufreq.c
@@ -0,0 +1,350 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * System Control and Power Interface (SCMI) based CPUFreq Interface driver
+ *
+ * Copyright (C) 2018-2021 ARM Ltd.
+ * Sudeep Holla <sudeep.holla@arm.com>
+ */
+
+#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+
+#include <linux/clk-provider.h>
+#include <linux/cpu.h>
+#include <linux/cpufreq.h>
+#include <linux/cpumask.h>
+#include <linux/energy_model.h>
+#include <linux/export.h>
+#include <linux/module.h>
+#include <linux/pm_opp.h>
+#include <linux/slab.h>
+#include <linux/scmi_protocol.h>
+#include <linux/types.h>
+#include <linux/units.h>
+
+struct scmi_data {
+ int domain_id;
+ int nr_opp;
+ struct device *cpu_dev;
+ cpumask_var_t opp_shared_cpus;
+};
+
+static struct scmi_protocol_handle *ph;
+static const struct scmi_perf_proto_ops *perf_ops;
+
+static unsigned int scmi_cpufreq_get_rate(unsigned int cpu)
+{
+ struct cpufreq_policy *policy = cpufreq_cpu_get_raw(cpu);
+ struct scmi_data *priv = policy->driver_data;
+ unsigned long rate;
+ int ret;
+
+ ret = perf_ops->freq_get(ph, priv->domain_id, &rate, false);
+ if (ret)
+ return 0;
+ return rate / 1000;
+}
+
+/*
+ * perf_ops->freq_set is not a synchronous, the actual OPP change will
+ * happen asynchronously and can get notified if the events are
+ * subscribed for by the SCMI firmware
+ */
+static int
+scmi_cpufreq_set_target(struct cpufreq_policy *policy, unsigned int index)
+{
+ struct scmi_data *priv = policy->driver_data;
+ u64 freq = policy->freq_table[index].frequency;
+
+ return perf_ops->freq_set(ph, priv->domain_id, freq * 1000, false);
+}
+
+static unsigned int scmi_cpufreq_fast_switch(struct cpufreq_policy *policy,
+ unsigned int target_freq)
+{
+ struct scmi_data *priv = policy->driver_data;
+
+ if (!perf_ops->freq_set(ph, priv->domain_id,
+ target_freq * 1000, true))
+ return target_freq;
+
+ return 0;
+}
+
+static int
+scmi_get_sharing_cpus(struct device *cpu_dev, struct cpumask *cpumask)
+{
+ int cpu, domain, tdomain;
+ struct device *tcpu_dev;
+
+ domain = perf_ops->device_domain_id(cpu_dev);
+ if (domain < 0)
+ return domain;
+
+ for_each_possible_cpu(cpu) {
+ if (cpu == cpu_dev->id)
+ continue;
+
+ tcpu_dev = get_cpu_device(cpu);
+ if (!tcpu_dev)
+ continue;
+
+ tdomain = perf_ops->device_domain_id(tcpu_dev);
+ if (tdomain == domain)
+ cpumask_set_cpu(cpu, cpumask);
+ }
+
+ return 0;
+}
+
+static int __maybe_unused
+scmi_get_cpu_power(struct device *cpu_dev, unsigned long *power,
+ unsigned long *KHz)
+{
+ enum scmi_power_scale power_scale = perf_ops->power_scale_get(ph);
+ unsigned long Hz;
+ int ret, domain;
+
+ domain = perf_ops->device_domain_id(cpu_dev);
+ if (domain < 0)
+ return domain;
+
+ /* Get the power cost of the performance domain. */
+ Hz = *KHz * 1000;
+ ret = perf_ops->est_power_get(ph, domain, &Hz, power);
+ if (ret)
+ return ret;
+
+ /* Convert the power to uW if it is mW (ignore bogoW) */
+ if (power_scale == SCMI_POWER_MILLIWATTS)
+ *power *= MICROWATT_PER_MILLIWATT;
+
+ /* The EM framework specifies the frequency in KHz. */
+ *KHz = Hz / 1000;
+
+ return 0;
+}
+
+static int scmi_cpufreq_init(struct cpufreq_policy *policy)
+{
+ int ret, nr_opp;
+ unsigned int latency;
+ struct device *cpu_dev;
+ struct scmi_data *priv;
+ struct cpufreq_frequency_table *freq_table;
+
+ cpu_dev = get_cpu_device(policy->cpu);
+ if (!cpu_dev) {
+ pr_err("failed to get cpu%d device\n", policy->cpu);
+ return -ENODEV;
+ }
+
+ priv = kzalloc(sizeof(*priv), GFP_KERNEL);
+ if (!priv)
+ return -ENOMEM;
+
+ if (!zalloc_cpumask_var(&priv->opp_shared_cpus, GFP_KERNEL)) {
+ ret = -ENOMEM;
+ goto out_free_priv;
+ }
+
+ /* Obtain CPUs that share SCMI performance controls */
+ ret = scmi_get_sharing_cpus(cpu_dev, policy->cpus);
+ if (ret) {
+ dev_warn(cpu_dev, "failed to get sharing cpumask\n");
+ goto out_free_cpumask;
+ }
+
+ /*
+ * Obtain CPUs that share performance levels.
+ * The OPP 'sharing cpus' info may come from DT through an empty opp
+ * table and opp-shared.
+ */
+ ret = dev_pm_opp_of_get_sharing_cpus(cpu_dev, priv->opp_shared_cpus);
+ if (ret || cpumask_empty(priv->opp_shared_cpus)) {
+ /*
+ * Either opp-table is not set or no opp-shared was found.
+ * Use the CPU mask from SCMI to designate CPUs sharing an OPP
+ * table.
+ */
+ cpumask_copy(priv->opp_shared_cpus, policy->cpus);
+ }
+
+ /*
+ * A previous CPU may have marked OPPs as shared for a few CPUs, based on
+ * what OPP core provided. If the current CPU is part of those few, then
+ * there is no need to add OPPs again.
+ */
+ nr_opp = dev_pm_opp_get_opp_count(cpu_dev);
+ if (nr_opp <= 0) {
+ ret = perf_ops->device_opps_add(ph, cpu_dev);
+ if (ret) {
+ dev_warn(cpu_dev, "failed to add opps to the device\n");
+ goto out_free_cpumask;
+ }
+
+ nr_opp = dev_pm_opp_get_opp_count(cpu_dev);
+ if (nr_opp <= 0) {
+ dev_err(cpu_dev, "%s: No OPPs for this device: %d\n",
+ __func__, nr_opp);
+
+ ret = -ENODEV;
+ goto out_free_opp;
+ }
+
+ ret = dev_pm_opp_set_sharing_cpus(cpu_dev, priv->opp_shared_cpus);
+ if (ret) {
+ dev_err(cpu_dev, "%s: failed to mark OPPs as shared: %d\n",
+ __func__, ret);
+
+ goto out_free_opp;
+ }
+
+ priv->nr_opp = nr_opp;
+ }
+
+ ret = dev_pm_opp_init_cpufreq_table(cpu_dev, &freq_table);
+ if (ret) {
+ dev_err(cpu_dev, "failed to init cpufreq table: %d\n", ret);
+ goto out_free_opp;
+ }
+
+ priv->cpu_dev = cpu_dev;
+ priv->domain_id = perf_ops->device_domain_id(cpu_dev);
+
+ policy->driver_data = priv;
+ policy->freq_table = freq_table;
+
+ /* SCMI allows DVFS request for any domain from any CPU */
+ policy->dvfs_possible_from_any_cpu = true;
+
+ latency = perf_ops->transition_latency_get(ph, cpu_dev);
+ if (!latency)
+ latency = CPUFREQ_ETERNAL;
+
+ policy->cpuinfo.transition_latency = latency;
+
+ policy->fast_switch_possible =
+ perf_ops->fast_switch_possible(ph, cpu_dev);
+
+ return 0;
+
+out_free_opp:
+ dev_pm_opp_remove_all_dynamic(cpu_dev);
+
+out_free_cpumask:
+ free_cpumask_var(priv->opp_shared_cpus);
+
+out_free_priv:
+ kfree(priv);
+
+ return ret;
+}
+
+static int scmi_cpufreq_exit(struct cpufreq_policy *policy)
+{
+ struct scmi_data *priv = policy->driver_data;
+
+ dev_pm_opp_free_cpufreq_table(priv->cpu_dev, &policy->freq_table);
+ dev_pm_opp_remove_all_dynamic(priv->cpu_dev);
+ free_cpumask_var(priv->opp_shared_cpus);
+ kfree(priv);
+
+ return 0;
+}
+
+static void scmi_cpufreq_register_em(struct cpufreq_policy *policy)
+{
+ struct em_data_callback em_cb = EM_DATA_CB(scmi_get_cpu_power);
+ enum scmi_power_scale power_scale = perf_ops->power_scale_get(ph);
+ struct scmi_data *priv = policy->driver_data;
+ bool em_power_scale = false;
+
+ /*
+ * This callback will be called for each policy, but we don't need to
+ * register with EM every time. Despite not being part of the same
+ * policy, some CPUs may still share their perf-domains, and a CPU from
+ * another policy may already have registered with EM on behalf of CPUs
+ * of this policy.
+ */
+ if (!priv->nr_opp)
+ return;
+
+ if (power_scale == SCMI_POWER_MILLIWATTS
+ || power_scale == SCMI_POWER_MICROWATTS)
+ em_power_scale = true;
+
+ em_dev_register_perf_domain(get_cpu_device(policy->cpu), priv->nr_opp,
+ &em_cb, priv->opp_shared_cpus,
+ em_power_scale);
+}
+
+static struct cpufreq_driver scmi_cpufreq_driver = {
+ .name = "scmi",
+ .flags = CPUFREQ_HAVE_GOVERNOR_PER_POLICY |
+ CPUFREQ_NEED_INITIAL_FREQ_CHECK |
+ CPUFREQ_IS_COOLING_DEV,
+ .verify = cpufreq_generic_frequency_table_verify,
+ .attr = cpufreq_generic_attr,
+ .target_index = scmi_cpufreq_set_target,
+ .fast_switch = scmi_cpufreq_fast_switch,
+ .get = scmi_cpufreq_get_rate,
+ .init = scmi_cpufreq_init,
+ .exit = scmi_cpufreq_exit,
+ .register_em = scmi_cpufreq_register_em,
+};
+
+static int scmi_cpufreq_probe(struct scmi_device *sdev)
+{
+ int ret;
+ struct device *dev = &sdev->dev;
+ const struct scmi_handle *handle;
+
+ handle = sdev->handle;
+
+ if (!handle)
+ return -ENODEV;
+
+ perf_ops = handle->devm_protocol_get(sdev, SCMI_PROTOCOL_PERF, &ph);
+ if (IS_ERR(perf_ops))
+ return PTR_ERR(perf_ops);
+
+#ifdef CONFIG_COMMON_CLK
+ /* dummy clock provider as needed by OPP if clocks property is used */
+ if (of_property_present(dev->of_node, "#clock-cells")) {
+ ret = devm_of_clk_add_hw_provider(dev, of_clk_hw_simple_get, NULL);
+ if (ret)
+ return dev_err_probe(dev, ret, "%s: registering clock provider failed\n", __func__);
+ }
+#endif
+
+ ret = cpufreq_register_driver(&scmi_cpufreq_driver);
+ if (ret) {
+ dev_err(dev, "%s: registering cpufreq failed, err: %d\n",
+ __func__, ret);
+ }
+
+ return ret;
+}
+
+static void scmi_cpufreq_remove(struct scmi_device *sdev)
+{
+ cpufreq_unregister_driver(&scmi_cpufreq_driver);
+}
+
+static const struct scmi_device_id scmi_id_table[] = {
+ { SCMI_PROTOCOL_PERF, "cpufreq" },
+ { },
+};
+MODULE_DEVICE_TABLE(scmi, scmi_id_table);
+
+static struct scmi_driver scmi_cpufreq_drv = {
+ .name = "scmi-cpufreq",
+ .probe = scmi_cpufreq_probe,
+ .remove = scmi_cpufreq_remove,
+ .id_table = scmi_id_table,
+};
+module_scmi_driver(scmi_cpufreq_drv);
+
+MODULE_AUTHOR("Sudeep Holla <sudeep.holla@arm.com>");
+MODULE_DESCRIPTION("ARM SCMI CPUFreq interface driver");
+MODULE_LICENSE("GPL v2");