summaryrefslogtreecommitdiffstats
path: root/drivers/cpufreq/cpufreq_conservative.c
diff options
context:
space:
mode:
authorLinus Torvalds <torvalds@linux-foundation.org>2026-08-23 13:28:57 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2026-08-23 13:28:57 -0700
commit4352b8aee98005853aa63f57d6377282de17a33f (patch)
tree27614d7a9ef05c32d089004e104364ce42324837 /drivers/cpufreq/cpufreq_conservative.c
downloadlinux-stable-4352b8aee98005853aa63f57d6377282de17a33f.tar.gz
linux-stable-4352b8aee98005853aa63f57d6377282de17a33f.zip
Merge tag 'i3c/for-7.3' of git://git.kernel.org/pub/scm/linux/kernel/git/i3c/linuxgrafted
Pull I3C updates from Alexandre Belloni: "A new driver this cycle, for the AMD AXI I3C controller. There are also new features such as IBI wakeup support, SETAASA device discovery and ACPI support for the the DAA methods, meaning we can now communicate with the SPD devices on DDR5 modules. New driver: - AMD AXI I3C master controller Subsystem: - I3C Common Command Code (CCC) handling improvements, especially around GET CCCs - SETAASA device discovery support - ACPI support for all existing DAA methods like SETDASA, SETNEWDA as well as I2C devices on I3C bus - IBI-based wakeup support Drivers: - dw: SETAASA support - mipi-i3c-hci: advertise IBI wakeup capability, AMD_PT I3C controller support, PIO queue management support for HCI v1.2 - renesas: improve suspend to RAM support, add runtime PM support" * tag 'i3c/for-7.3' of git://git.kernel.org/pub/scm/linux/kernel/git/i3c/linux: (70 commits) i3c: dw: reduce do_daa time if there's no client i3c: mipi-i3c-hci: Add support for AMD_PT I3C controller i3c: mipi-i3c-hci: Add PIO queue management support for HCI v1.2 i3c: mipi-i3c-hci: Fix missing STAT_IBI_STATUS_THLD in PIO mode i3c: dw: rename "pclk" to "apb" to match dt-binding i3c: dw: make struct dw_i3c_cmd smaller i3c: dw: use COMMAND_PORT_TRANSFER_ARG instead of hardcoding i3c: renesas: Don't register devices when ENTDAA times out i3c: master: dw-i3c-master: fix OD timing for first broadcast i3c: mipi-i3c-hci: Advertise IBI wakeup capability i3c: mipi-i3c-hci: Factor out i3c_hci_sysdev() i3c: mipi-i3c-hci-pci: Propagate I3C wakeup requirements to PCI i3c: master: Reject IBI requests from non-IBI-capable devices i3c: master: Add helper to query bus wakeup requirements i3c: master: Report wakeup events for IBIs i3c: master: Support IBI-based wakeup capability i3c: master: Fix potential UAF in i3c_device_match() i3c: master: Fix potential UAF in i3c_device_uevent() i3c: Make dev->desc locking assumptions explicit i3c: master: Fix use-after-free of master->this ...
Diffstat (limited to 'drivers/cpufreq/cpufreq_conservative.c')
-rw-r--r--drivers/cpufreq/cpufreq_conservative.c345
1 files changed, 345 insertions, 0 deletions
diff --git a/drivers/cpufreq/cpufreq_conservative.c b/drivers/cpufreq/cpufreq_conservative.c
new file mode 100644
index 000000000..0b32ae28e
--- /dev/null
+++ b/drivers/cpufreq/cpufreq_conservative.c
@@ -0,0 +1,345 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * drivers/cpufreq/cpufreq_conservative.c
+ *
+ * Copyright (C) 2001 Russell King
+ * (C) 2003 Venkatesh Pallipadi <venkatesh.pallipadi@intel.com>.
+ * Jun Nakajima <jun.nakajima@intel.com>
+ * (C) 2009 Alexander Clouter <alex@digriz.org.uk>
+ */
+
+#include <linux/slab.h>
+#include "cpufreq_governor.h"
+
+struct cs_policy_dbs_info {
+ struct policy_dbs_info policy_dbs;
+ unsigned int down_skip;
+ unsigned int requested_freq;
+};
+
+static inline struct cs_policy_dbs_info *to_dbs_info(struct policy_dbs_info *policy_dbs)
+{
+ return container_of(policy_dbs, struct cs_policy_dbs_info, policy_dbs);
+}
+
+struct cs_dbs_tuners {
+ unsigned int down_threshold;
+ unsigned int freq_step;
+};
+
+/* Conservative governor macros */
+#define DEF_FREQUENCY_UP_THRESHOLD (80)
+#define DEF_FREQUENCY_DOWN_THRESHOLD (20)
+#define DEF_FREQUENCY_STEP (5)
+#define DEF_SAMPLING_DOWN_FACTOR (1)
+#define MAX_SAMPLING_DOWN_FACTOR (10)
+
+static inline unsigned int get_freq_step(struct cs_dbs_tuners *cs_tuners,
+ struct cpufreq_policy *policy)
+{
+ unsigned int freq_step = (cs_tuners->freq_step * policy->max) / 100;
+
+ /* max freq cannot be less than 100. But who knows... */
+ if (unlikely(freq_step == 0))
+ freq_step = DEF_FREQUENCY_STEP;
+
+ return freq_step;
+}
+
+/*
+ * Every sampling_rate, we check, if current idle time is less than 20%
+ * (default), then we try to increase frequency. Every sampling_rate *
+ * sampling_down_factor, we check, if current idle time is more than 80%
+ * (default), then we try to decrease frequency
+ *
+ * Frequency updates happen at minimum steps of 5% (default) of maximum
+ * frequency
+ */
+static unsigned int cs_dbs_update(struct cpufreq_policy *policy)
+{
+ struct policy_dbs_info *policy_dbs = policy->governor_data;
+ struct cs_policy_dbs_info *dbs_info = to_dbs_info(policy_dbs);
+ unsigned int requested_freq = dbs_info->requested_freq;
+ struct dbs_data *dbs_data = policy_dbs->dbs_data;
+ struct cs_dbs_tuners *cs_tuners = dbs_data->tuners;
+ unsigned int load = dbs_update(policy);
+ unsigned int freq_step;
+
+ /*
+ * break out if we 'cannot' reduce the speed as the user might
+ * want freq_step to be zero
+ */
+ if (cs_tuners->freq_step == 0)
+ goto out;
+
+ /*
+ * If requested_freq is out of range, it is likely that the limits
+ * changed in the meantime, so fall back to current frequency in that
+ * case.
+ */
+ if (requested_freq > policy->max || requested_freq < policy->min) {
+ requested_freq = policy->cur;
+ dbs_info->requested_freq = requested_freq;
+ }
+
+ freq_step = get_freq_step(cs_tuners, policy);
+
+ /*
+ * Decrease requested_freq one freq_step for each idle period that
+ * we didn't update the frequency.
+ */
+ if (policy_dbs->idle_periods < UINT_MAX) {
+ unsigned int freq_steps = policy_dbs->idle_periods * freq_step;
+
+ if (requested_freq > policy->min + freq_steps)
+ requested_freq -= freq_steps;
+ else
+ requested_freq = policy->min;
+
+ policy_dbs->idle_periods = UINT_MAX;
+ }
+
+ /* Check for frequency increase */
+ if (load > dbs_data->up_threshold) {
+ dbs_info->down_skip = 0;
+
+ requested_freq += freq_step;
+ if (requested_freq > policy->max)
+ requested_freq = policy->max;
+
+ __cpufreq_driver_target(policy, requested_freq,
+ CPUFREQ_RELATION_HE);
+ dbs_info->requested_freq = requested_freq;
+ goto out;
+ }
+
+ /* if sampling_down_factor is active break out early */
+ if (++dbs_info->down_skip < dbs_data->sampling_down_factor)
+ goto out;
+ dbs_info->down_skip = 0;
+
+ /* Check for frequency decrease */
+ if (load < cs_tuners->down_threshold) {
+ if (requested_freq > policy->min + freq_step)
+ requested_freq -= freq_step;
+ else
+ requested_freq = policy->min;
+
+ __cpufreq_driver_target(policy, requested_freq,
+ CPUFREQ_RELATION_LE);
+ dbs_info->requested_freq = requested_freq;
+ }
+
+ out:
+ return dbs_data->sampling_rate;
+}
+
+/************************** sysfs interface ************************/
+
+static ssize_t sampling_down_factor_store(struct gov_attr_set *attr_set,
+ const char *buf, size_t count)
+{
+ struct dbs_data *dbs_data = to_dbs_data(attr_set);
+ unsigned int input;
+ int ret;
+ ret = kstrtouint(buf, 0, &input);
+
+ if (ret || input > MAX_SAMPLING_DOWN_FACTOR || input < 1)
+ return -EINVAL;
+
+ dbs_data->sampling_down_factor = input;
+ return count;
+}
+
+static ssize_t up_threshold_store(struct gov_attr_set *attr_set,
+ const char *buf, size_t count)
+{
+ struct dbs_data *dbs_data = to_dbs_data(attr_set);
+ struct cs_dbs_tuners *cs_tuners = dbs_data->tuners;
+ unsigned int input;
+ int ret;
+ ret = kstrtouint(buf, 0, &input);
+
+ if (ret || input > 100 || input <= cs_tuners->down_threshold)
+ return -EINVAL;
+
+ dbs_data->up_threshold = input;
+ return count;
+}
+
+static ssize_t down_threshold_store(struct gov_attr_set *attr_set,
+ const char *buf, size_t count)
+{
+ struct dbs_data *dbs_data = to_dbs_data(attr_set);
+ struct cs_dbs_tuners *cs_tuners = dbs_data->tuners;
+ unsigned int input;
+ int ret;
+ ret = kstrtouint(buf, 0, &input);
+
+ /* cannot be lower than 1 otherwise freq will not fall */
+ if (ret || input < 1 || input >= dbs_data->up_threshold)
+ return -EINVAL;
+
+ cs_tuners->down_threshold = input;
+ return count;
+}
+
+static ssize_t ignore_nice_load_store(struct gov_attr_set *attr_set,
+ const char *buf, size_t count)
+{
+ struct dbs_data *dbs_data = to_dbs_data(attr_set);
+ unsigned int input;
+ int ret;
+
+ ret = kstrtouint(buf, 0, &input);
+ if (ret)
+ return ret;
+
+ if (input > 1)
+ input = 1;
+
+ if (input == dbs_data->ignore_nice_load) /* nothing to do */
+ return count;
+
+ dbs_data->ignore_nice_load = input;
+
+ /* we need to re-evaluate prev_cpu_idle */
+ gov_update_cpu_data(dbs_data);
+
+ return count;
+}
+
+static ssize_t freq_step_store(struct gov_attr_set *attr_set, const char *buf,
+ size_t count)
+{
+ struct dbs_data *dbs_data = to_dbs_data(attr_set);
+ struct cs_dbs_tuners *cs_tuners = dbs_data->tuners;
+ unsigned int input;
+ int ret;
+ ret = kstrtouint(buf, 0, &input);
+
+ if (ret)
+ return ret;
+
+ if (input > 100)
+ input = 100;
+
+ /*
+ * no need to test here if freq_step is zero as the user might actually
+ * want this, they would be crazy though :)
+ */
+ cs_tuners->freq_step = input;
+ return count;
+}
+
+gov_show_one_common(sampling_rate);
+gov_show_one_common(sampling_down_factor);
+gov_show_one_common(up_threshold);
+gov_show_one_common(ignore_nice_load);
+gov_show_one(cs, down_threshold);
+gov_show_one(cs, freq_step);
+
+gov_attr_rw(sampling_rate);
+gov_attr_rw(sampling_down_factor);
+gov_attr_rw(up_threshold);
+gov_attr_rw(ignore_nice_load);
+gov_attr_rw(down_threshold);
+gov_attr_rw(freq_step);
+
+static struct attribute *cs_attrs[] = {
+ &sampling_rate.attr,
+ &sampling_down_factor.attr,
+ &up_threshold.attr,
+ &down_threshold.attr,
+ &ignore_nice_load.attr,
+ &freq_step.attr,
+ NULL
+};
+ATTRIBUTE_GROUPS(cs);
+
+/************************** sysfs end ************************/
+
+static struct policy_dbs_info *cs_alloc(void)
+{
+ struct cs_policy_dbs_info *dbs_info;
+
+ dbs_info = kzalloc_obj(*dbs_info);
+ return dbs_info ? &dbs_info->policy_dbs : NULL;
+}
+
+static void cs_free(struct policy_dbs_info *policy_dbs)
+{
+ kfree(to_dbs_info(policy_dbs));
+}
+
+static int cs_init(struct dbs_data *dbs_data)
+{
+ struct cs_dbs_tuners *tuners;
+
+ tuners = kzalloc_obj(*tuners);
+ if (!tuners)
+ return -ENOMEM;
+
+ tuners->down_threshold = DEF_FREQUENCY_DOWN_THRESHOLD;
+ tuners->freq_step = DEF_FREQUENCY_STEP;
+ dbs_data->up_threshold = DEF_FREQUENCY_UP_THRESHOLD;
+ dbs_data->sampling_down_factor = DEF_SAMPLING_DOWN_FACTOR;
+ dbs_data->ignore_nice_load = 0;
+ dbs_data->tuners = tuners;
+
+ return 0;
+}
+
+static void cs_exit(struct dbs_data *dbs_data)
+{
+ kfree(dbs_data->tuners);
+}
+
+static void cs_start(struct cpufreq_policy *policy)
+{
+ struct cs_policy_dbs_info *dbs_info = to_dbs_info(policy->governor_data);
+
+ dbs_info->down_skip = 0;
+ dbs_info->requested_freq = policy->cur;
+}
+
+static void cs_limits(struct cpufreq_policy *policy)
+{
+ struct cs_policy_dbs_info *dbs_info = to_dbs_info(policy->governor_data);
+
+ /*
+ * The limits have changed, so may have the current frequency. Reset
+ * requested_freq to avoid any unintended outcomes due to the mismatch.
+ */
+ dbs_info->requested_freq = policy->cur;
+}
+
+static struct dbs_governor cs_governor = {
+ .gov = CPUFREQ_DBS_GOVERNOR_INITIALIZER("conservative"),
+ .kobj_type = { .default_groups = cs_groups },
+ .gov_dbs_update = cs_dbs_update,
+ .alloc = cs_alloc,
+ .free = cs_free,
+ .init = cs_init,
+ .exit = cs_exit,
+ .start = cs_start,
+ .limits = cs_limits,
+};
+
+#define CPU_FREQ_GOV_CONSERVATIVE (cs_governor.gov)
+
+MODULE_AUTHOR("Alexander Clouter <alex@digriz.org.uk>");
+MODULE_DESCRIPTION("'cpufreq_conservative' - A dynamic cpufreq governor for "
+ "Low Latency Frequency Transition capable processors "
+ "optimised for use in a battery environment");
+MODULE_LICENSE("GPL");
+
+#ifdef CONFIG_CPU_FREQ_DEFAULT_GOV_CONSERVATIVE
+struct cpufreq_governor *cpufreq_default_governor(void)
+{
+ return &CPU_FREQ_GOV_CONSERVATIVE;
+}
+#endif
+
+cpufreq_governor_init(CPU_FREQ_GOV_CONSERVATIVE);
+cpufreq_governor_exit(CPU_FREQ_GOV_CONSERVATIVE);