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![Lukasz Luba](/assets/img/avatar_default.png)
The Energy Model supports power values expressed in milli-Watts or in an 'abstract scale'. Update the related comments is the code to reflect that state. Reviewed-by: Quentin Perret <qperret@google.com> Signed-off-by: Lukasz Luba <lukasz.luba@arm.com> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
374 lines
9.1 KiB
C
374 lines
9.1 KiB
C
// SPDX-License-Identifier: GPL-2.0
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/*
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* Energy Model of devices
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*
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* Copyright (c) 2018-2020, Arm ltd.
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* Written by: Quentin Perret, Arm ltd.
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* Improvements provided by: Lukasz Luba, Arm ltd.
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*/
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#define pr_fmt(fmt) "energy_model: " fmt
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#include <linux/cpu.h>
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#include <linux/cpumask.h>
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#include <linux/debugfs.h>
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#include <linux/energy_model.h>
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#include <linux/sched/topology.h>
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#include <linux/slab.h>
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/*
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* Mutex serializing the registrations of performance domains and letting
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* callbacks defined by drivers sleep.
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*/
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static DEFINE_MUTEX(em_pd_mutex);
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static bool _is_cpu_device(struct device *dev)
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{
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return (dev->bus == &cpu_subsys);
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}
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#ifdef CONFIG_DEBUG_FS
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static struct dentry *rootdir;
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static void em_debug_create_ps(struct em_perf_state *ps, struct dentry *pd)
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{
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struct dentry *d;
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char name[24];
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snprintf(name, sizeof(name), "ps:%lu", ps->frequency);
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/* Create per-ps directory */
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d = debugfs_create_dir(name, pd);
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debugfs_create_ulong("frequency", 0444, d, &ps->frequency);
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debugfs_create_ulong("power", 0444, d, &ps->power);
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debugfs_create_ulong("cost", 0444, d, &ps->cost);
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}
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static int em_debug_cpus_show(struct seq_file *s, void *unused)
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{
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seq_printf(s, "%*pbl\n", cpumask_pr_args(to_cpumask(s->private)));
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return 0;
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}
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DEFINE_SHOW_ATTRIBUTE(em_debug_cpus);
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static int em_debug_units_show(struct seq_file *s, void *unused)
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{
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struct em_perf_domain *pd = s->private;
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char *units = pd->milliwatts ? "milliWatts" : "bogoWatts";
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seq_printf(s, "%s\n", units);
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return 0;
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}
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DEFINE_SHOW_ATTRIBUTE(em_debug_units);
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static void em_debug_create_pd(struct device *dev)
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{
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struct dentry *d;
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int i;
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/* Create the directory of the performance domain */
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d = debugfs_create_dir(dev_name(dev), rootdir);
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if (_is_cpu_device(dev))
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debugfs_create_file("cpus", 0444, d, dev->em_pd->cpus,
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&em_debug_cpus_fops);
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debugfs_create_file("units", 0444, d, dev->em_pd, &em_debug_units_fops);
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/* Create a sub-directory for each performance state */
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for (i = 0; i < dev->em_pd->nr_perf_states; i++)
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em_debug_create_ps(&dev->em_pd->table[i], d);
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}
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static void em_debug_remove_pd(struct device *dev)
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{
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struct dentry *debug_dir;
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debug_dir = debugfs_lookup(dev_name(dev), rootdir);
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debugfs_remove_recursive(debug_dir);
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}
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static int __init em_debug_init(void)
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{
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/* Create /sys/kernel/debug/energy_model directory */
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rootdir = debugfs_create_dir("energy_model", NULL);
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return 0;
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}
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core_initcall(em_debug_init);
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#else /* CONFIG_DEBUG_FS */
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static void em_debug_create_pd(struct device *dev) {}
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static void em_debug_remove_pd(struct device *dev) {}
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#endif
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static int em_create_perf_table(struct device *dev, struct em_perf_domain *pd,
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int nr_states, struct em_data_callback *cb)
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{
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unsigned long opp_eff, prev_opp_eff = ULONG_MAX;
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unsigned long power, freq, prev_freq = 0;
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struct em_perf_state *table;
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int i, ret;
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u64 fmax;
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table = kcalloc(nr_states, sizeof(*table), GFP_KERNEL);
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if (!table)
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return -ENOMEM;
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/* Build the list of performance states for this performance domain */
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for (i = 0, freq = 0; i < nr_states; i++, freq++) {
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/*
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* active_power() is a driver callback which ceils 'freq' to
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* lowest performance state of 'dev' above 'freq' and updates
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* 'power' and 'freq' accordingly.
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*/
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ret = cb->active_power(&power, &freq, dev);
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if (ret) {
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dev_err(dev, "EM: invalid perf. state: %d\n",
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ret);
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goto free_ps_table;
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}
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/*
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* We expect the driver callback to increase the frequency for
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* higher performance states.
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*/
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if (freq <= prev_freq) {
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dev_err(dev, "EM: non-increasing freq: %lu\n",
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freq);
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goto free_ps_table;
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}
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/*
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* The power returned by active_state() is expected to be
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* positive and to fit into 16 bits.
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*/
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if (!power || power > EM_MAX_POWER) {
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dev_err(dev, "EM: invalid power: %lu\n",
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power);
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goto free_ps_table;
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}
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table[i].power = power;
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table[i].frequency = prev_freq = freq;
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/*
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* The hertz/watts efficiency ratio should decrease as the
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* frequency grows on sane platforms. But this isn't always
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* true in practice so warn the user if a higher OPP is more
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* power efficient than a lower one.
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*/
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opp_eff = freq / power;
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if (opp_eff >= prev_opp_eff)
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dev_dbg(dev, "EM: hertz/watts ratio non-monotonically decreasing: em_perf_state %d >= em_perf_state%d\n",
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i, i - 1);
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prev_opp_eff = opp_eff;
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}
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/* Compute the cost of each performance state. */
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fmax = (u64) table[nr_states - 1].frequency;
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for (i = 0; i < nr_states; i++) {
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table[i].cost = div64_u64(fmax * table[i].power,
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table[i].frequency);
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}
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pd->table = table;
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pd->nr_perf_states = nr_states;
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return 0;
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free_ps_table:
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kfree(table);
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return -EINVAL;
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}
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static int em_create_pd(struct device *dev, int nr_states,
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struct em_data_callback *cb, cpumask_t *cpus)
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{
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struct em_perf_domain *pd;
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struct device *cpu_dev;
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int cpu, ret;
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if (_is_cpu_device(dev)) {
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pd = kzalloc(sizeof(*pd) + cpumask_size(), GFP_KERNEL);
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if (!pd)
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return -ENOMEM;
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cpumask_copy(em_span_cpus(pd), cpus);
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} else {
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pd = kzalloc(sizeof(*pd), GFP_KERNEL);
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if (!pd)
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return -ENOMEM;
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}
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ret = em_create_perf_table(dev, pd, nr_states, cb);
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if (ret) {
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kfree(pd);
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return ret;
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}
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if (_is_cpu_device(dev))
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for_each_cpu(cpu, cpus) {
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cpu_dev = get_cpu_device(cpu);
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cpu_dev->em_pd = pd;
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}
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dev->em_pd = pd;
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return 0;
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}
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/**
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* em_pd_get() - Return the performance domain for a device
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* @dev : Device to find the performance domain for
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*
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* Returns the performance domain to which @dev belongs, or NULL if it doesn't
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* exist.
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*/
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struct em_perf_domain *em_pd_get(struct device *dev)
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{
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if (IS_ERR_OR_NULL(dev))
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return NULL;
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return dev->em_pd;
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}
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EXPORT_SYMBOL_GPL(em_pd_get);
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/**
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* em_cpu_get() - Return the performance domain for a CPU
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* @cpu : CPU to find the performance domain for
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*
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* Returns the performance domain to which @cpu belongs, or NULL if it doesn't
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* exist.
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*/
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struct em_perf_domain *em_cpu_get(int cpu)
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{
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struct device *cpu_dev;
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cpu_dev = get_cpu_device(cpu);
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if (!cpu_dev)
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return NULL;
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return em_pd_get(cpu_dev);
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}
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EXPORT_SYMBOL_GPL(em_cpu_get);
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/**
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* em_dev_register_perf_domain() - Register the Energy Model (EM) for a device
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* @dev : Device for which the EM is to register
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* @nr_states : Number of performance states to register
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* @cb : Callback functions providing the data of the Energy Model
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* @cpus : Pointer to cpumask_t, which in case of a CPU device is
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* obligatory. It can be taken from i.e. 'policy->cpus'. For other
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* type of devices this should be set to NULL.
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* @milliwatts : Flag indicating that the power values are in milliWatts or
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* in some other scale. It must be set properly.
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*
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* Create Energy Model tables for a performance domain using the callbacks
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* defined in cb.
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*
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* The @milliwatts is important to set with correct value. Some kernel
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* sub-systems might rely on this flag and check if all devices in the EM are
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* using the same scale.
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*
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* If multiple clients register the same performance domain, all but the first
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* registration will be ignored.
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*
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* Return 0 on success
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*/
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int em_dev_register_perf_domain(struct device *dev, unsigned int nr_states,
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struct em_data_callback *cb, cpumask_t *cpus,
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bool milliwatts)
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{
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unsigned long cap, prev_cap = 0;
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int cpu, ret;
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if (!dev || !nr_states || !cb)
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return -EINVAL;
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/*
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* Use a mutex to serialize the registration of performance domains and
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* let the driver-defined callback functions sleep.
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*/
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mutex_lock(&em_pd_mutex);
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if (dev->em_pd) {
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ret = -EEXIST;
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goto unlock;
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}
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if (_is_cpu_device(dev)) {
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if (!cpus) {
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dev_err(dev, "EM: invalid CPU mask\n");
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ret = -EINVAL;
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goto unlock;
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}
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for_each_cpu(cpu, cpus) {
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if (em_cpu_get(cpu)) {
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dev_err(dev, "EM: exists for CPU%d\n", cpu);
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ret = -EEXIST;
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goto unlock;
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}
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/*
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* All CPUs of a domain must have the same
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* micro-architecture since they all share the same
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* table.
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*/
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cap = arch_scale_cpu_capacity(cpu);
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if (prev_cap && prev_cap != cap) {
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dev_err(dev, "EM: CPUs of %*pbl must have the same capacity\n",
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cpumask_pr_args(cpus));
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ret = -EINVAL;
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goto unlock;
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}
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prev_cap = cap;
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}
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}
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ret = em_create_pd(dev, nr_states, cb, cpus);
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if (ret)
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goto unlock;
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dev->em_pd->milliwatts = milliwatts;
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em_debug_create_pd(dev);
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dev_info(dev, "EM: created perf domain\n");
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unlock:
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mutex_unlock(&em_pd_mutex);
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return ret;
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}
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EXPORT_SYMBOL_GPL(em_dev_register_perf_domain);
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/**
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* em_dev_unregister_perf_domain() - Unregister Energy Model (EM) for a device
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* @dev : Device for which the EM is registered
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*
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* Unregister the EM for the specified @dev (but not a CPU device).
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*/
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void em_dev_unregister_perf_domain(struct device *dev)
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{
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if (IS_ERR_OR_NULL(dev) || !dev->em_pd)
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return;
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if (_is_cpu_device(dev))
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return;
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/*
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* The mutex separates all register/unregister requests and protects
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* from potential clean-up/setup issues in the debugfs directories.
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* The debugfs directory name is the same as device's name.
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*/
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mutex_lock(&em_pd_mutex);
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em_debug_remove_pd(dev);
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kfree(dev->em_pd->table);
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kfree(dev->em_pd);
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dev->em_pd = NULL;
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mutex_unlock(&em_pd_mutex);
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}
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EXPORT_SYMBOL_GPL(em_dev_unregister_perf_domain);
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