1 files changed, 424 insertions, 0 deletions

diff --git a/drivers/cpufreq/e_powersaver.c b/drivers/cpufreq/e_powersaver.c
new file mode 100644
index 000000000..ab93bce8a
--- /dev/null
+++ b/drivers/cpufreq/e_powersaver.c
@@ -0,0 +1,424 @@
+// 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(sizeof(*eps_acpi_cpu_perf),
+				      GFP_KERNEL);
+	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;
+	u32 lo, hi;
+
+	if (cpu)
+		return 0;
+	centaur = eps_cpu[cpu];
+	if (centaur == NULL)
+		return 0;
+
+	/* Return current frequency */
+	rdmsr(MSR_IA32_PERF_STATUS, lo, hi);
+	return centaur->fsb * ((lo >> 8) & 0xff);
+}
+
+static int eps_set_state(struct eps_cpu_data *centaur,
+			 struct cpufreq_policy *policy,
+			 u32 dest_state)
+{
+	u32 lo, hi;
+	int i;
+
+	/* Wait while CPU is busy */
+	rdmsr(MSR_IA32_PERF_STATUS, lo, hi);
+	i = 0;
+	while (lo & ((1 << 16) | (1 << 17))) {
+		udelay(16);
+		rdmsr(MSR_IA32_PERF_STATUS, lo, hi);
+		i++;
+		if (unlikely(i > 64)) {
+			return -ENODEV;
+		}
+	}
+	/* Set new multiplier and voltage */
+	wrmsr(MSR_IA32_PERF_CTL, dest_state & 0xffff, 0);
+	/* Wait until transition end */
+	i = 0;
+	do {
+		udelay(16);
+		rdmsr(MSR_IA32_PERF_STATUS, lo, hi);
+		i++;
+		if (unlikely(i > 64)) {
+			return -ENODEV;
+		}
+	} while (lo & ((1 << 16) | (1 << 17)));
+
+#ifdef DEBUG
+	{
+	u8 current_multiplier, current_voltage;
+
+	/* Print voltage and multiplier */
+	rdmsr(MSR_IA32_PERF_STATUS, lo, hi);
+	current_voltage = lo & 0xff;
+	pr_info("Current voltage = %dmV\n", current_voltage * 16 + 700);
+	current_multiplier = (lo >> 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;
+	u32 lo, hi;
+	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:
+		rdmsr(0x1153, lo, hi);
+		brand = (((lo >> 2) ^ lo) >> 18) & 3;
+		pr_cont("Model A ");
+		break;
+	case 13:
+		rdmsr(0x1154, lo, hi);
+		brand = (((lo >> 4) ^ (lo >> 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 */
+	rdmsrl(MSR_IA32_MISC_ENABLE, val);
+	if (!(val & MSR_IA32_MISC_ENABLE_ENHANCED_SPEEDSTEP)) {
+		val |= MSR_IA32_MISC_ENABLE_ENHANCED_SPEEDSTEP;
+		wrmsrl(MSR_IA32_MISC_ENABLE, val);
+		/* Can be locked at 0 */
+		rdmsrl(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 */
+	rdmsr(MSR_IA32_PERF_STATUS, lo, hi);
+	current_voltage = lo & 0xff;
+	pr_info("Current voltage = %dmV\n", current_voltage * 16 + 700);
+	current_multiplier = (lo >> 8) & 0xff;
+	pr_info("Current multiplier = %d\n", current_multiplier);
+
+	/* Print limits */
+	max_voltage = hi & 0xff;
+	pr_info("Highest voltage = %dmV\n", max_voltage * 16 + 700);
+	max_multiplier = (hi >> 8) & 0xff;
+	pr_info("Highest multiplier = %d\n", max_multiplier);
+	min_voltage = (hi >> 16) & 0xff;
+	pr_info("Lowest voltage = %dmV\n", min_voltage * 16 + 700);
+	min_multiplier = (hi >> 24) & 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(struct_size(centaur, freq_table, states + 1),
+			  GFP_KERNEL);
+	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 int eps_cpu_exit(struct cpufreq_policy *policy)
+{
+	unsigned int cpu = policy->cpu;
+
+	/* Bye */
+	kfree(eps_cpu[cpu]);
+	eps_cpu[cpu] = NULL;
+	return 0;
+}
+
+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",
+	.attr		= cpufreq_generic_attr,
+};
+
+
+/* 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);