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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/e_powersaver.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/e_powersaver.c')
-rw-r--r--drivers/cpufreq/e_powersaver.c419
1 files changed, 419 insertions, 0 deletions
diff --git a/drivers/cpufreq/e_powersaver.c b/drivers/cpufreq/e_powersaver.c
new file mode 100644
index 000000000..54689ebad
--- /dev/null
+++ b/drivers/cpufreq/e_powersaver.c
@@ -0,0 +1,419 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Based on documentation provided by Dave Jones. Thanks!
+ *
+ * BIG FAT DISCLAIMER: Work in progress code. Possibly *dangerous*
+ */
+
+#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/init.h>
+#include <linux/cpufreq.h>
+#include <linux/ioport.h>
+#include <linux/slab.h>
+#include <linux/timex.h>
+#include <linux/io.h>
+#include <linux/delay.h>
+
+#include <asm/cpu_device_id.h>
+#include <asm/msr.h>
+#include <asm/tsc.h>
+
+#if IS_ENABLED(CONFIG_ACPI_PROCESSOR)
+#include <linux/acpi.h>
+#include <acpi/processor.h>
+#endif
+
+#define EPS_BRAND_C7M 0
+#define EPS_BRAND_C7 1
+#define EPS_BRAND_EDEN 2
+#define EPS_BRAND_C3 3
+#define EPS_BRAND_C7D 4
+
+struct eps_cpu_data {
+ u32 fsb;
+#if IS_ENABLED(CONFIG_ACPI_PROCESSOR)
+ u32 bios_limit;
+#endif
+ struct cpufreq_frequency_table freq_table[];
+};
+
+static struct eps_cpu_data *eps_cpu[NR_CPUS];
+
+/* Module parameters */
+static int freq_failsafe_off;
+static int voltage_failsafe_off;
+static int set_max_voltage;
+
+#if IS_ENABLED(CONFIG_ACPI_PROCESSOR)
+static int ignore_acpi_limit;
+
+static struct acpi_processor_performance *eps_acpi_cpu_perf;
+
+/* Minimum necessary to get acpi_processor_get_bios_limit() working */
+static int eps_acpi_init(void)
+{
+ eps_acpi_cpu_perf = kzalloc_obj(*eps_acpi_cpu_perf);
+ if (!eps_acpi_cpu_perf)
+ return -ENOMEM;
+
+ if (!zalloc_cpumask_var(&eps_acpi_cpu_perf->shared_cpu_map,
+ GFP_KERNEL)) {
+ kfree(eps_acpi_cpu_perf);
+ eps_acpi_cpu_perf = NULL;
+ return -ENOMEM;
+ }
+
+ if (acpi_processor_register_performance(eps_acpi_cpu_perf, 0)) {
+ free_cpumask_var(eps_acpi_cpu_perf->shared_cpu_map);
+ kfree(eps_acpi_cpu_perf);
+ eps_acpi_cpu_perf = NULL;
+ return -EIO;
+ }
+ return 0;
+}
+
+static int eps_acpi_exit(struct cpufreq_policy *policy)
+{
+ if (eps_acpi_cpu_perf) {
+ acpi_processor_unregister_performance(0);
+ free_cpumask_var(eps_acpi_cpu_perf->shared_cpu_map);
+ kfree(eps_acpi_cpu_perf);
+ eps_acpi_cpu_perf = NULL;
+ }
+ return 0;
+}
+#endif
+
+static unsigned int eps_get(unsigned int cpu)
+{
+ struct eps_cpu_data *centaur;
+ u64 val;
+
+ if (cpu)
+ return 0;
+ centaur = eps_cpu[cpu];
+ if (centaur == NULL)
+ return 0;
+
+ /* Return current frequency */
+ rdmsrq(MSR_IA32_PERF_STATUS, val);
+ return centaur->fsb * ((val >> 8) & 0xff);
+}
+
+static int eps_set_state(struct eps_cpu_data *centaur,
+ struct cpufreq_policy *policy,
+ u32 dest_state)
+{
+ u64 val;
+ int i;
+
+ /* Wait while CPU is busy */
+ rdmsrq(MSR_IA32_PERF_STATUS, val);
+ i = 0;
+ while (val & ((1 << 16) | (1 << 17))) {
+ udelay(16);
+ rdmsrq(MSR_IA32_PERF_STATUS, val);
+ i++;
+ if (unlikely(i > 64)) {
+ return -ENODEV;
+ }
+ }
+ /* Set new multiplier and voltage */
+ wrmsrq(MSR_IA32_PERF_CTL, dest_state & 0xffff);
+ /* Wait until transition end */
+ i = 0;
+ do {
+ udelay(16);
+ rdmsrq(MSR_IA32_PERF_STATUS, val);
+ i++;
+ if (unlikely(i > 64)) {
+ return -ENODEV;
+ }
+ } while (val & ((1 << 16) | (1 << 17)));
+
+#ifdef DEBUG
+ {
+ u8 current_multiplier, current_voltage;
+
+ /* Print voltage and multiplier */
+ rdmsrq(MSR_IA32_PERF_STATUS, val);
+ current_voltage = val & 0xff;
+ pr_info("Current voltage = %dmV\n", current_voltage * 16 + 700);
+ current_multiplier = (val >> 8) & 0xff;
+ pr_info("Current multiplier = %d\n", current_multiplier);
+ }
+#endif
+ return 0;
+}
+
+static int eps_target(struct cpufreq_policy *policy, unsigned int index)
+{
+ struct eps_cpu_data *centaur;
+ unsigned int cpu = policy->cpu;
+ unsigned int dest_state;
+ int ret;
+
+ if (unlikely(eps_cpu[cpu] == NULL))
+ return -ENODEV;
+ centaur = eps_cpu[cpu];
+
+ /* Make frequency transition */
+ dest_state = centaur->freq_table[index].driver_data & 0xffff;
+ ret = eps_set_state(centaur, policy, dest_state);
+ if (ret)
+ pr_err("Timeout!\n");
+ return ret;
+}
+
+static int eps_cpu_init(struct cpufreq_policy *policy)
+{
+ unsigned int i;
+ u64 val;
+ u8 current_multiplier, current_voltage;
+ u8 max_multiplier, max_voltage;
+ u8 min_multiplier, min_voltage;
+ u8 brand = 0;
+ u32 fsb;
+ struct eps_cpu_data *centaur;
+ struct cpuinfo_x86 *c = &cpu_data(0);
+ struct cpufreq_frequency_table *f_table;
+ int k, step, voltage;
+ int states;
+#if IS_ENABLED(CONFIG_ACPI_PROCESSOR)
+ unsigned int limit;
+#endif
+
+ if (policy->cpu != 0)
+ return -ENODEV;
+
+ /* Check brand */
+ pr_info("Detected VIA ");
+
+ switch (c->x86_model) {
+ case 10:
+ rdmsrq(0x1153, val);
+ brand = (((val >> 2) ^ val) >> 18) & 3;
+ pr_cont("Model A ");
+ break;
+ case 13:
+ rdmsrq(0x1154, val);
+ brand = (((val >> 4) ^ (val >> 2))) & 0x000000ff;
+ pr_cont("Model D ");
+ break;
+ }
+
+ switch (brand) {
+ case EPS_BRAND_C7M:
+ pr_cont("C7-M\n");
+ break;
+ case EPS_BRAND_C7:
+ pr_cont("C7\n");
+ break;
+ case EPS_BRAND_EDEN:
+ pr_cont("Eden\n");
+ break;
+ case EPS_BRAND_C7D:
+ pr_cont("C7-D\n");
+ break;
+ case EPS_BRAND_C3:
+ pr_cont("C3\n");
+ return -ENODEV;
+ }
+ /* Enable Enhanced PowerSaver */
+ rdmsrq(MSR_IA32_MISC_ENABLE, val);
+ if (!(val & MSR_IA32_MISC_ENABLE_ENHANCED_SPEEDSTEP)) {
+ val |= MSR_IA32_MISC_ENABLE_ENHANCED_SPEEDSTEP;
+ wrmsrq(MSR_IA32_MISC_ENABLE, val);
+ /* Can be locked at 0 */
+ rdmsrq(MSR_IA32_MISC_ENABLE, val);
+ if (!(val & MSR_IA32_MISC_ENABLE_ENHANCED_SPEEDSTEP)) {
+ pr_info("Can't enable Enhanced PowerSaver\n");
+ return -ENODEV;
+ }
+ }
+
+ /* Print voltage and multiplier */
+ rdmsrq(MSR_IA32_PERF_STATUS, val);
+ current_voltage = val & 0xff;
+ pr_info("Current voltage = %dmV\n", current_voltage * 16 + 700);
+ current_multiplier = (val >> 8) & 0xff;
+ pr_info("Current multiplier = %d\n", current_multiplier);
+
+ /* Print limits */
+ max_voltage = (val >> 32) & 0xff;
+ pr_info("Highest voltage = %dmV\n", max_voltage * 16 + 700);
+ max_multiplier = (val >> 40) & 0xff;
+ pr_info("Highest multiplier = %d\n", max_multiplier);
+ min_voltage = (val >> 48) & 0xff;
+ pr_info("Lowest voltage = %dmV\n", min_voltage * 16 + 700);
+ min_multiplier = (val >> 56) & 0xff;
+ pr_info("Lowest multiplier = %d\n", min_multiplier);
+
+ /* Sanity checks */
+ if (current_multiplier == 0 || max_multiplier == 0
+ || min_multiplier == 0)
+ return -EINVAL;
+ if (current_multiplier > max_multiplier
+ || max_multiplier <= min_multiplier)
+ return -EINVAL;
+ if (current_voltage > 0x1f || max_voltage > 0x1f)
+ return -EINVAL;
+ if (max_voltage < min_voltage
+ || current_voltage < min_voltage
+ || current_voltage > max_voltage)
+ return -EINVAL;
+
+ /* Check for systems using underclocked CPU */
+ if (!freq_failsafe_off && max_multiplier != current_multiplier) {
+ pr_info("Your processor is running at different frequency then its maximum. Aborting.\n");
+ pr_info("You can use freq_failsafe_off option to disable this check.\n");
+ return -EINVAL;
+ }
+ if (!voltage_failsafe_off && max_voltage != current_voltage) {
+ pr_info("Your processor is running at different voltage then its maximum. Aborting.\n");
+ pr_info("You can use voltage_failsafe_off option to disable this check.\n");
+ return -EINVAL;
+ }
+
+ /* Calc FSB speed */
+ fsb = cpu_khz / current_multiplier;
+
+#if IS_ENABLED(CONFIG_ACPI_PROCESSOR)
+ /* Check for ACPI processor speed limit */
+ if (!ignore_acpi_limit && !eps_acpi_init()) {
+ if (!acpi_processor_get_bios_limit(policy->cpu, &limit)) {
+ pr_info("ACPI limit %u.%uGHz\n",
+ limit/1000000,
+ (limit%1000000)/10000);
+ eps_acpi_exit(policy);
+ /* Check if max_multiplier is in BIOS limits */
+ if (limit && max_multiplier * fsb > limit) {
+ pr_info("Aborting\n");
+ return -EINVAL;
+ }
+ }
+ }
+#endif
+
+ /* Allow user to set lower maximum voltage then that reported
+ * by processor */
+ if (brand == EPS_BRAND_C7M && set_max_voltage) {
+ u32 v;
+
+ /* Change mV to something hardware can use */
+ v = (set_max_voltage - 700) / 16;
+ /* Check if voltage is within limits */
+ if (v >= min_voltage && v <= max_voltage) {
+ pr_info("Setting %dmV as maximum\n", v * 16 + 700);
+ max_voltage = v;
+ }
+ }
+
+ /* Calc number of p-states supported */
+ if (brand == EPS_BRAND_C7M)
+ states = max_multiplier - min_multiplier + 1;
+ else
+ states = 2;
+
+ /* Allocate private data and frequency table for current cpu */
+ centaur = kzalloc_flex(*centaur, freq_table, states + 1);
+ if (!centaur)
+ return -ENOMEM;
+ eps_cpu[0] = centaur;
+
+ /* Copy basic values */
+ centaur->fsb = fsb;
+#if IS_ENABLED(CONFIG_ACPI_PROCESSOR)
+ centaur->bios_limit = limit;
+#endif
+
+ /* Fill frequency and MSR value table */
+ f_table = &centaur->freq_table[0];
+ if (brand != EPS_BRAND_C7M) {
+ f_table[0].frequency = fsb * min_multiplier;
+ f_table[0].driver_data = (min_multiplier << 8) | min_voltage;
+ f_table[1].frequency = fsb * max_multiplier;
+ f_table[1].driver_data = (max_multiplier << 8) | max_voltage;
+ f_table[2].frequency = CPUFREQ_TABLE_END;
+ } else {
+ k = 0;
+ step = ((max_voltage - min_voltage) * 256)
+ / (max_multiplier - min_multiplier);
+ for (i = min_multiplier; i <= max_multiplier; i++) {
+ voltage = (k * step) / 256 + min_voltage;
+ f_table[k].frequency = fsb * i;
+ f_table[k].driver_data = (i << 8) | voltage;
+ k++;
+ }
+ f_table[k].frequency = CPUFREQ_TABLE_END;
+ }
+
+ policy->cpuinfo.transition_latency = 140000; /* 844mV -> 700mV in ns */
+ policy->freq_table = &centaur->freq_table[0];
+
+ return 0;
+}
+
+static void eps_cpu_exit(struct cpufreq_policy *policy)
+{
+ unsigned int cpu = policy->cpu;
+
+ /* Bye */
+ kfree(eps_cpu[cpu]);
+ eps_cpu[cpu] = NULL;
+}
+
+static struct cpufreq_driver eps_driver = {
+ .verify = cpufreq_generic_frequency_table_verify,
+ .target_index = eps_target,
+ .init = eps_cpu_init,
+ .exit = eps_cpu_exit,
+ .get = eps_get,
+ .name = "e_powersaver",
+};
+
+
+/* This driver will work only on Centaur C7 processors with
+ * Enhanced SpeedStep/PowerSaver registers */
+static const struct x86_cpu_id eps_cpu_id[] = {
+ X86_MATCH_VENDOR_FAM_FEATURE(CENTAUR, 6, X86_FEATURE_EST, NULL),
+ {}
+};
+MODULE_DEVICE_TABLE(x86cpu, eps_cpu_id);
+
+static int __init eps_init(void)
+{
+ if (!x86_match_cpu(eps_cpu_id) || boot_cpu_data.x86_model < 10)
+ return -ENODEV;
+ if (cpufreq_register_driver(&eps_driver))
+ return -EINVAL;
+ return 0;
+}
+
+static void __exit eps_exit(void)
+{
+ cpufreq_unregister_driver(&eps_driver);
+}
+
+/* Allow user to overclock his machine or to change frequency to higher after
+ * unloading module */
+module_param(freq_failsafe_off, int, 0644);
+MODULE_PARM_DESC(freq_failsafe_off, "Disable current vs max frequency check");
+module_param(voltage_failsafe_off, int, 0644);
+MODULE_PARM_DESC(voltage_failsafe_off, "Disable current vs max voltage check");
+#if IS_ENABLED(CONFIG_ACPI_PROCESSOR)
+module_param(ignore_acpi_limit, int, 0644);
+MODULE_PARM_DESC(ignore_acpi_limit, "Don't check ACPI's processor speed limit");
+#endif
+module_param(set_max_voltage, int, 0644);
+MODULE_PARM_DESC(set_max_voltage, "Set maximum CPU voltage (mV) C7-M only");
+
+MODULE_AUTHOR("Rafal Bilski <rafalbilski@interia.pl>");
+MODULE_DESCRIPTION("Enhanced PowerSaver driver for VIA C7 CPU's.");
+MODULE_LICENSE("GPL");
+
+module_init(eps_init);
+module_exit(eps_exit);