diff options
Diffstat (limited to 'drivers/cpufreq/scpi-cpufreq.c')
| -rw-r--r-- | drivers/cpufreq/scpi-cpufreq.c | 229 |
1 files changed, 229 insertions, 0 deletions
diff --git a/drivers/cpufreq/scpi-cpufreq.c b/drivers/cpufreq/scpi-cpufreq.c new file mode 100644 index 0000000000..d33be56983 --- /dev/null +++ b/drivers/cpufreq/scpi-cpufreq.c @@ -0,0 +1,229 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * System Control and Power Interface (SCPI) based CPUFreq Interface driver + * + * Copyright (C) 2015 ARM Ltd. + * Sudeep Holla <sudeep.holla@arm.com> + */ + +#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt + +#include <linux/clk.h> +#include <linux/cpu.h> +#include <linux/cpufreq.h> +#include <linux/cpumask.h> +#include <linux/export.h> +#include <linux/module.h> +#include <linux/platform_device.h> +#include <linux/pm_opp.h> +#include <linux/scpi_protocol.h> +#include <linux/slab.h> +#include <linux/types.h> + +struct scpi_data { + struct clk *clk; + struct device *cpu_dev; +}; + +static struct scpi_ops *scpi_ops; + +static unsigned int scpi_cpufreq_get_rate(unsigned int cpu) +{ + struct cpufreq_policy *policy = cpufreq_cpu_get_raw(cpu); + struct scpi_data *priv = policy->driver_data; + unsigned long rate = clk_get_rate(priv->clk); + + return rate / 1000; +} + +static int +scpi_cpufreq_set_target(struct cpufreq_policy *policy, unsigned int index) +{ + u64 rate = policy->freq_table[index].frequency * 1000; + struct scpi_data *priv = policy->driver_data; + int ret; + + ret = clk_set_rate(priv->clk, rate); + + if (ret) + return ret; + + if (clk_get_rate(priv->clk) != rate) + return -EIO; + + return 0; +} + +static int +scpi_get_sharing_cpus(struct device *cpu_dev, struct cpumask *cpumask) +{ + int cpu, domain, tdomain; + struct device *tcpu_dev; + + domain = scpi_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 = scpi_ops->device_domain_id(tcpu_dev); + if (tdomain == domain) + cpumask_set_cpu(cpu, cpumask); + } + + return 0; +} + +static int scpi_cpufreq_init(struct cpufreq_policy *policy) +{ + int ret; + unsigned int latency; + struct device *cpu_dev; + struct scpi_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; + } + + ret = scpi_ops->add_opps_to_device(cpu_dev); + if (ret) { + dev_warn(cpu_dev, "failed to add opps to the device\n"); + return ret; + } + + ret = scpi_get_sharing_cpus(cpu_dev, policy->cpus); + if (ret) { + dev_warn(cpu_dev, "failed to get sharing cpumask\n"); + return ret; + } + + ret = dev_pm_opp_set_sharing_cpus(cpu_dev, policy->cpus); + if (ret) { + dev_err(cpu_dev, "%s: failed to mark OPPs as shared: %d\n", + __func__, ret); + return ret; + } + + ret = dev_pm_opp_get_opp_count(cpu_dev); + if (ret <= 0) { + dev_dbg(cpu_dev, "OPP table is not ready, deferring probe\n"); + ret = -EPROBE_DEFER; + goto out_free_opp; + } + + priv = kzalloc(sizeof(*priv), GFP_KERNEL); + if (!priv) { + ret = -ENOMEM; + goto out_free_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_priv; + } + + priv->cpu_dev = cpu_dev; + priv->clk = clk_get(cpu_dev, NULL); + if (IS_ERR(priv->clk)) { + dev_err(cpu_dev, "%s: Failed to get clk for cpu: %d\n", + __func__, cpu_dev->id); + ret = PTR_ERR(priv->clk); + goto out_free_cpufreq_table; + } + + policy->driver_data = priv; + policy->freq_table = freq_table; + + /* scpi allows DVFS request for any domain from any CPU */ + policy->dvfs_possible_from_any_cpu = true; + + latency = scpi_ops->get_transition_latency(cpu_dev); + if (!latency) + latency = CPUFREQ_ETERNAL; + + policy->cpuinfo.transition_latency = latency; + + policy->fast_switch_possible = false; + + return 0; + +out_free_cpufreq_table: + dev_pm_opp_free_cpufreq_table(cpu_dev, &freq_table); +out_free_priv: + kfree(priv); +out_free_opp: + dev_pm_opp_remove_all_dynamic(cpu_dev); + + return ret; +} + +static int scpi_cpufreq_exit(struct cpufreq_policy *policy) +{ + struct scpi_data *priv = policy->driver_data; + + clk_put(priv->clk); + dev_pm_opp_free_cpufreq_table(priv->cpu_dev, &policy->freq_table); + dev_pm_opp_remove_all_dynamic(priv->cpu_dev); + kfree(priv); + + return 0; +} + +static struct cpufreq_driver scpi_cpufreq_driver = { + .name = "scpi-cpufreq", + .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, + .get = scpi_cpufreq_get_rate, + .init = scpi_cpufreq_init, + .exit = scpi_cpufreq_exit, + .target_index = scpi_cpufreq_set_target, + .register_em = cpufreq_register_em_with_opp, +}; + +static int scpi_cpufreq_probe(struct platform_device *pdev) +{ + int ret; + + scpi_ops = get_scpi_ops(); + if (!scpi_ops) + return -EIO; + + ret = cpufreq_register_driver(&scpi_cpufreq_driver); + if (ret) + dev_err(&pdev->dev, "%s: registering cpufreq failed, err: %d\n", + __func__, ret); + return ret; +} + +static void scpi_cpufreq_remove(struct platform_device *pdev) +{ + cpufreq_unregister_driver(&scpi_cpufreq_driver); + scpi_ops = NULL; +} + +static struct platform_driver scpi_cpufreq_platdrv = { + .driver = { + .name = "scpi-cpufreq", + }, + .probe = scpi_cpufreq_probe, + .remove_new = scpi_cpufreq_remove, +}; +module_platform_driver(scpi_cpufreq_platdrv); + +MODULE_ALIAS("platform:scpi-cpufreq"); +MODULE_AUTHOR("Sudeep Holla <sudeep.holla@arm.com>"); +MODULE_DESCRIPTION("ARM SCPI CPUFreq interface driver"); +MODULE_LICENSE("GPL v2"); |