--- /dev/null
+
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright 2023 Linaro Limited
+ *
+ *
+ * Thermal subsystem debug support
+ */
+#include <linux/debugfs.h>
+#include <linux/ktime.h>
+#include <linux/list.h>
+#include <linux/minmax.h>
+#include <linux/mutex.h>
+#include <linux/thermal.h>
+
+static struct dentry *d_root;
+static struct dentry *d_cdev;
+
+/*
+ * Length of the string containing the thermal zone id or the cooling
+ * device id, including the ending nul character. We can reasonably
+ * assume there won't be more than 256 thermal zones as the maximum
+ * observed today is around 32.
+ */
+#define IDSLENGTH 4
+
+/*
+ * The cooling device transition list is stored in a hash table where
+ * the size is CDEVSTATS_HASH_SIZE. The majority of cooling devices
+ * have dozen of states but some can have much more, so a hash table
+ * is more adequate in this case, because the cost of browsing the entire
+ * list when storing the transitions may not be negligible.
+ */
+#define CDEVSTATS_HASH_SIZE 16
+
+/**
+ * struct cdev_debugfs - per cooling device statistics structure
+ * A cooling device can have a high number of states. Showing the
+ * transitions on a matrix based representation can be overkill given
+ * most of the transitions won't happen and we end up with a matrix
+ * filled with zero. Instead, we show the transitions which actually
+ * happened.
+ *
+ * Every transition updates the current_state and the timestamp. The
+ * transitions and the durations are stored in lists.
+ *
+ * @total: the number of transitions for this cooling device
+ * @current_state: the current cooling device state
+ * @timestamp: the state change timestamp
+ * @transitions: an array of lists containing the state transitions
+ * @durations: an array of lists containing the residencies of each state
+ */
+struct cdev_debugfs {
+ u32 total;
+ int current_state;
+ ktime_t timestamp;
+ struct list_head transitions[CDEVSTATS_HASH_SIZE];
+ struct list_head durations[CDEVSTATS_HASH_SIZE];
+};
+
+/**
+ * struct cdev_value - Common structure for cooling device entry
+ *
+ * The following common structure allows to store the information
+ * related to the transitions and to the state residencies. They are
+ * identified with a id which is associated to a value. It is used as
+ * nodes for the "transitions" and "durations" above.
+ *
+ * @node: node to insert the structure in a list
+ * @id: identifier of the value which can be a state or a transition
+ * @residency: a ktime_t representing a state residency duration
+ * @count: a number of occurrences
+ */
+struct cdev_record {
+ struct list_head node;
+ int id;
+ union {
+ ktime_t residency;
+ u64 count;
+ };
+};
+
+/**
+ * struct thermal_debugfs - High level structure for a thermal object in debugfs
+ *
+ * The thermal_debugfs structure is the common structure used by the
+ * cooling device to compute the statistics.
+ *
+ * @d_top: top directory of the thermal object directory
+ * @lock: per object lock to protect the internals
+ *
+ * @cdev: a cooling device debug structure
+ */
+struct thermal_debugfs {
+ struct dentry *d_top;
+ struct mutex lock;
+ union {
+ struct cdev_debugfs cdev_dbg;
+ };
+};
+
+void thermal_debug_init(void)
+{
+ d_root = debugfs_create_dir("thermal", NULL);
+ if (!d_root)
+ return;
+
+ d_cdev = debugfs_create_dir("cooling_devices", d_root);
+}
+
+static struct thermal_debugfs *thermal_debugfs_add_id(struct dentry *d, int id)
+{
+ struct thermal_debugfs *thermal_dbg;
+ char ids[IDSLENGTH];
+
+ thermal_dbg = kzalloc(sizeof(*thermal_dbg), GFP_KERNEL);
+ if (!thermal_dbg)
+ return NULL;
+
+ mutex_init(&thermal_dbg->lock);
+
+ snprintf(ids, IDSLENGTH, "%d", id);
+
+ thermal_dbg->d_top = debugfs_create_dir(ids, d);
+ if (!thermal_dbg->d_top) {
+ kfree(thermal_dbg);
+ return NULL;
+ }
+
+ return thermal_dbg;
+}
+
+static void thermal_debugfs_remove_id(struct thermal_debugfs *thermal_dbg)
+{
+ if (!thermal_dbg)
+ return;
+
+ debugfs_remove(thermal_dbg->d_top);
+
+ kfree(thermal_dbg);
+}
+
+static struct cdev_record *
+thermal_debugfs_cdev_record_alloc(struct thermal_debugfs *thermal_dbg,
+ struct list_head *lists, int id)
+{
+ struct cdev_record *cdev_record;
+
+ cdev_record = kzalloc(sizeof(*cdev_record), GFP_KERNEL);
+ if (!cdev_record)
+ return NULL;
+
+ cdev_record->id = id;
+ INIT_LIST_HEAD(&cdev_record->node);
+ list_add_tail(&cdev_record->node,
+ &lists[cdev_record->id % CDEVSTATS_HASH_SIZE]);
+
+ return cdev_record;
+}
+
+static struct cdev_record *
+thermal_debugfs_cdev_record_find(struct thermal_debugfs *thermal_dbg,
+ struct list_head *lists, int id)
+{
+ struct cdev_record *entry;
+
+ list_for_each_entry(entry, &lists[id % CDEVSTATS_HASH_SIZE], node)
+ if (entry->id == id)
+ return entry;
+
+ return NULL;
+}
+
+static struct cdev_record *
+thermal_debugfs_cdev_record_get(struct thermal_debugfs *thermal_dbg,
+ struct list_head *lists, int id)
+{
+ struct cdev_record *cdev_record;
+
+ cdev_record = thermal_debugfs_cdev_record_find(thermal_dbg, lists, id);
+ if (cdev_record)
+ return cdev_record;
+
+ return thermal_debugfs_cdev_record_alloc(thermal_dbg, lists, id);
+}
+
+static void thermal_debugfs_cdev_clear(struct cdev_debugfs *cdev_dbg)
+{
+ int i;
+ struct cdev_record *entry, *tmp;
+
+ for (i = 0; i < CDEVSTATS_HASH_SIZE; i++) {
+
+ list_for_each_entry_safe(entry, tmp,
+ &cdev_dbg->transitions[i], node) {
+ list_del(&entry->node);
+ kfree(entry);
+ }
+
+ list_for_each_entry_safe(entry, tmp,
+ &cdev_dbg->durations[i], node) {
+ list_del(&entry->node);
+ kfree(entry);
+ }
+ }
+
+ cdev_dbg->total = 0;
+}
+
+static void *cdev_seq_start(struct seq_file *s, loff_t *pos)
+{
+ struct thermal_debugfs *thermal_dbg = s->private;
+
+ mutex_lock(&thermal_dbg->lock);
+
+ return (*pos < CDEVSTATS_HASH_SIZE) ? pos : NULL;
+}
+
+static void *cdev_seq_next(struct seq_file *s, void *v, loff_t *pos)
+{
+ (*pos)++;
+
+ return (*pos < CDEVSTATS_HASH_SIZE) ? pos : NULL;
+}
+
+static void cdev_seq_stop(struct seq_file *s, void *v)
+{
+ struct thermal_debugfs *thermal_dbg = s->private;
+
+ mutex_unlock(&thermal_dbg->lock);
+}
+
+static int cdev_tt_seq_show(struct seq_file *s, void *v)
+{
+ struct thermal_debugfs *thermal_dbg = s->private;
+ struct cdev_debugfs *cdev_dbg = &thermal_dbg->cdev_dbg;
+ struct list_head *transitions = cdev_dbg->transitions;
+ struct cdev_record *entry;
+ int i = *(loff_t *)v;
+
+ if (!i)
+ seq_puts(s, "Transition\tOccurences\n");
+
+ list_for_each_entry(entry, &transitions[i], node) {
+ /*
+ * Assuming maximum cdev states is 1024, the longer
+ * string for a transition would be "1024->1024\0"
+ */
+ char buffer[11];
+
+ snprintf(buffer, ARRAY_SIZE(buffer), "%d->%d",
+ entry->id >> 16, entry->id & 0xFFFF);
+
+ seq_printf(s, "%-10s\t%-10llu\n", buffer, entry->count);
+ }
+
+ return 0;
+}
+
+static const struct seq_operations tt_sops = {
+ .start = cdev_seq_start,
+ .next = cdev_seq_next,
+ .stop = cdev_seq_stop,
+ .show = cdev_tt_seq_show,
+};
+
+DEFINE_SEQ_ATTRIBUTE(tt);
+
+static int cdev_dt_seq_show(struct seq_file *s, void *v)
+{
+ struct thermal_debugfs *thermal_dbg = s->private;
+ struct cdev_debugfs *cdev_dbg = &thermal_dbg->cdev_dbg;
+ struct list_head *durations = cdev_dbg->durations;
+ struct cdev_record *entry;
+ int i = *(loff_t *)v;
+
+ if (!i)
+ seq_puts(s, "State\tResidency\n");
+
+ list_for_each_entry(entry, &durations[i], node) {
+ s64 duration = ktime_to_ms(entry->residency);
+
+ if (entry->id == cdev_dbg->current_state)
+ duration += ktime_ms_delta(ktime_get(),
+ cdev_dbg->timestamp);
+
+ seq_printf(s, "%-5d\t%-10llu\n", entry->id, duration);
+ }
+
+ return 0;
+}
+
+static const struct seq_operations dt_sops = {
+ .start = cdev_seq_start,
+ .next = cdev_seq_next,
+ .stop = cdev_seq_stop,
+ .show = cdev_dt_seq_show,
+};
+
+DEFINE_SEQ_ATTRIBUTE(dt);
+
+static int cdev_clear_set(void *data, u64 val)
+{
+ struct thermal_debugfs *thermal_dbg = data;
+
+ if (!val)
+ return -EINVAL;
+
+ mutex_lock(&thermal_dbg->lock);
+
+ thermal_debugfs_cdev_clear(&thermal_dbg->cdev_dbg);
+
+ mutex_unlock(&thermal_dbg->lock);
+
+ return 0;
+}
+
+DEFINE_DEBUGFS_ATTRIBUTE(cdev_clear_fops, NULL, cdev_clear_set, "%llu\n");
+
+/**
+ * thermal_debug_cdev_state_update - Update a cooling device state change
+ *
+ * Computes a transition and the duration of the previous state residency.
+ *
+ * @cdev : a pointer to a cooling device
+ * @new_state: an integer corresponding to the new cooling device state
+ */
+void thermal_debug_cdev_state_update(const struct thermal_cooling_device *cdev,
+ int new_state)
+{
+ struct thermal_debugfs *thermal_dbg = cdev->debugfs;
+ struct cdev_debugfs *cdev_dbg;
+ struct cdev_record *cdev_record;
+ int transition, old_state;
+
+ if (!thermal_dbg || (thermal_dbg->cdev_dbg.current_state == new_state))
+ return;
+
+ mutex_lock(&thermal_dbg->lock);
+
+ cdev_dbg = &thermal_dbg->cdev_dbg;
+
+ old_state = cdev_dbg->current_state;
+
+ /*
+ * Get the old state information in the durations list. If
+ * this one does not exist, a new allocated one will be
+ * returned. Recompute the total duration in the old state and
+ * get a new timestamp for the new state.
+ */
+ cdev_record = thermal_debugfs_cdev_record_get(thermal_dbg,
+ cdev_dbg->durations,
+ old_state);
+ if (cdev_record) {
+ ktime_t now = ktime_get();
+ ktime_t delta = ktime_sub(now, cdev_dbg->timestamp);
+ cdev_record->residency = ktime_add(cdev_record->residency, delta);
+ cdev_dbg->timestamp = now;
+ }
+
+ cdev_dbg->current_state = new_state;
+ transition = (old_state << 16) | new_state;
+
+ /*
+ * Get the transition in the transitions list. If this one
+ * does not exist, a new allocated one will be returned.
+ * Increment the occurrence of this transition which is stored
+ * in the value field.
+ */
+ cdev_record = thermal_debugfs_cdev_record_get(thermal_dbg,
+ cdev_dbg->transitions,
+ transition);
+ if (cdev_record)
+ cdev_record->count++;
+
+ cdev_dbg->total++;
+
+ mutex_unlock(&thermal_dbg->lock);
+}
+
+/**
+ * thermal_debug_cdev_add - Add a cooling device debugfs entry
+ *
+ * Allocates a cooling device object for debug, initializes the
+ * statistics and create the entries in sysfs.
+ * @cdev: a pointer to a cooling device
+ */
+void thermal_debug_cdev_add(struct thermal_cooling_device *cdev)
+{
+ struct thermal_debugfs *thermal_dbg;
+ struct cdev_debugfs *cdev_dbg;
+ int i;
+
+ thermal_dbg = thermal_debugfs_add_id(d_cdev, cdev->id);
+ if (!thermal_dbg)
+ return;
+
+ cdev_dbg = &thermal_dbg->cdev_dbg;
+
+ for (i = 0; i < CDEVSTATS_HASH_SIZE; i++) {
+ INIT_LIST_HEAD(&cdev_dbg->transitions[i]);
+ INIT_LIST_HEAD(&cdev_dbg->durations[i]);
+ }
+
+ cdev_dbg->current_state = 0;
+ cdev_dbg->timestamp = ktime_get();
+
+ debugfs_create_file("trans_table", 0400, thermal_dbg->d_top,
+ thermal_dbg, &tt_fops);
+
+ debugfs_create_file("time_in_state_ms", 0400, thermal_dbg->d_top,
+ thermal_dbg, &dt_fops);
+
+ debugfs_create_file("clear", 0200, thermal_dbg->d_top,
+ thermal_dbg, &cdev_clear_fops);
+
+ debugfs_create_u32("total_trans", 0400, thermal_dbg->d_top,
+ &cdev_dbg->total);
+
+ cdev->debugfs = thermal_dbg;
+}
+
+/**
+ * thermal_debug_cdev_remove - Remove a cooling device debugfs entry
+ *
+ * Frees the statistics memory data and remove the debugfs entry
+ *
+ * @cdev: a pointer to a cooling device
+ */
+void thermal_debug_cdev_remove(struct thermal_cooling_device *cdev)
+{
+ struct thermal_debugfs *thermal_dbg = cdev->debugfs;
+
+ if (!thermal_dbg)
+ return;
+
+ mutex_lock(&thermal_dbg->lock);
+
+ thermal_debugfs_cdev_clear(&thermal_dbg->cdev_dbg);
+ cdev->debugfs = NULL;
+
+ mutex_unlock(&thermal_dbg->lock);
+
+ thermal_debugfs_remove_id(thermal_dbg);
+}
projects / linux.git / commitdiff