3 files changed, 344 insertions, 0 deletions

diff --git a/arch/i386/kernel/cpu/cpufreq/Kconfig b/arch/i386/kernel/cpu/cpufreq/Kconfig
index 5299c5bf4454..6c52182ca323 100644
--- a/arch/i386/kernel/cpu/cpufreq/Kconfig
+++ b/arch/i386/kernel/cpu/cpufreq/Kconfig
@@ -217,6 +217,15 @@ config X86_LONGHAUL
 
           If in doubt, say N.
 
+config X86_E_POWERSAVER
+        tristate "VIA C7 Enhanced PowerSaver (EXPERIMENTAL)"
+        select CPU_FREQ_TABLE
+        depends on EXPERIMENTAL
+        help
+          This adds the CPUFreq driver for VIA C7 processors.
+
+          If in doubt, say N.
+
 comment "shared options"
 
 config X86_ACPI_CPUFREQ_PROC_INTF
diff --git a/arch/i386/kernel/cpu/cpufreq/Makefile b/arch/i386/kernel/cpu/cpufreq/Makefile
index 8de3abe322a9..560f7760dae5 100644
--- a/arch/i386/kernel/cpu/cpufreq/Makefile
+++ b/arch/i386/kernel/cpu/cpufreq/Makefile
@@ -2,6 +2,7 @@ obj-$(CONFIG_X86_POWERNOW_K6)		+= powernow-k6.o
 obj-$(CONFIG_X86_POWERNOW_K7)           += powernow-k7.o
 obj-$(CONFIG_X86_POWERNOW_K8)           += powernow-k8.o
 obj-$(CONFIG_X86_LONGHAUL)              += longhaul.o
+obj-$(CONFIG_X86_E_POWERSAVER)          += e_powersaver.o
 obj-$(CONFIG_ELAN_CPUFREQ)              += elanfreq.o
 obj-$(CONFIG_SC520_CPUFREQ)             += sc520_freq.o
 obj-$(CONFIG_X86_LONGRUN)               += longrun.o  
diff --git a/arch/i386/kernel/cpu/cpufreq/e_powersaver.c b/arch/i386/kernel/cpu/cpufreq/e_powersaver.c
new file mode 100644
index 000000000000..3243725f80ca
--- /dev/null
+++ b/arch/i386/kernel/cpu/cpufreq/e_powersaver.c
@@ -0,0 +1,334 @@
+/*
+ *  Based on documentation provided by Dave Jones. Thanks!
+ *
+ *  Licensed under the terms of the GNU GPL License version 2.
+ *
+ *  BIG FAT DISCLAIMER: Work in progress code. Possibly *dangerous*
+ */
+
+#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 <asm/msr.h>
+#include <asm/tsc.h>
+#include <asm/timex.h>
+#include <asm/io.h>
+#include <asm/delay.h>
+
+#define EPS_BRAND_C7M   0
+#define EPS_BRAND_C7    1
+#define EPS_BRAND_EDEN  2
+#define EPS_BRAND_C3    3
+
+struct eps_cpu_data {
+        u32 fsb;
+        struct cpufreq_frequency_table freq_table[];
+};
+
+static struct eps_cpu_data *eps_cpu[NR_CPUS];
+
+
+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,
+                         unsigned int cpu,
+                         u32 dest_state)
+{
+        struct cpufreq_freqs freqs;
+        u32 lo, hi;
+        int err = 0;
+        int i;
+
+        freqs.old = eps_get(cpu);
+        freqs.new = centaur->fsb * ((dest_state >> 8) & 0xff);
+        freqs.cpu = cpu;
+        cpufreq_notify_transition(&freqs, CPUFREQ_PRECHANGE);
+
+        /* 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)) {
+                        err = -ENODEV;
+                        goto postchange;
+                }
+        }
+        /* 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)) {
+                        err = -ENODEV;
+                        goto postchange;
+                }
+        } while (lo & ((1 << 16) | (1 << 17)));
+
+        /* Return current frequency */
+postchange:
+        rdmsr(MSR_IA32_PERF_STATUS, lo, hi);
+        freqs.new = centaur->fsb * ((lo >> 8) & 0xff);
+
+        cpufreq_notify_transition(&freqs, CPUFREQ_POSTCHANGE);
+        return err;
+}
+
+static int eps_target(struct cpufreq_policy *policy,
+                               unsigned int target_freq,
+                               unsigned int relation)
+{
+        struct eps_cpu_data *centaur;
+        unsigned int newstate = 0;
+        unsigned int cpu = policy->cpu;
+        unsigned int dest_state;
+        int ret;
+
+        if (unlikely(eps_cpu[cpu] == NULL))
+                return -ENODEV;
+        centaur = eps_cpu[cpu];
+
+        if (unlikely(cpufreq_frequency_table_target(policy,
+                        &eps_cpu[cpu]->freq_table[0],
+                        target_freq,
+                        relation,
+                        &newstate))) {
+                return -EINVAL;
+        }
+
+        /* Make frequency transition */
+        dest_state = centaur->freq_table[newstate].index & 0xffff;
+        ret = eps_set_state(centaur, cpu, dest_state);
+        if (ret)
+                printk(KERN_ERR "eps: Timeout!\n");
+        return ret;
+}
+
+static int eps_verify(struct cpufreq_policy *policy)
+{
+        return cpufreq_frequency_table_verify(policy,
+                        &eps_cpu[policy->cpu]->freq_table[0]);
+}
+
+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;
+        u32 fsb;
+        struct eps_cpu_data *centaur;
+        struct cpufreq_frequency_table *f_table;
+        int k, step, voltage;
+        int ret;
+        int states;
+
+        if (policy->cpu != 0)
+                return -ENODEV;
+
+        /* Check brand */
+        printk("eps: Detected VIA ");
+        rdmsr(0x1153, lo, hi);
+        brand = (((lo >> 2) ^ lo) >> 18) & 3;
+        switch(brand) {
+        case EPS_BRAND_C7M:
+                printk("C7-M\n");
+                break;
+        case EPS_BRAND_C7:
+                printk("C7\n");
+                break;
+        case EPS_BRAND_EDEN:
+                printk("Eden\n");
+                break;
+        case EPS_BRAND_C3:
+                printk("C3\n");
+                return -ENODEV;
+                break;
+        }
+        /* Enable Enhanced PowerSaver */
+        rdmsrl(MSR_IA32_MISC_ENABLE, val);
+        if (!(val & 1 << 16)) {
+                val |= 1 << 16;
+                wrmsrl(MSR_IA32_MISC_ENABLE, val);
+                /* Can be locked at 0 */
+                rdmsrl(MSR_IA32_MISC_ENABLE, val);
+                if (!(val & 1 << 16)) {
+                        printk("eps: Can't enable Enhanced PowerSaver\n");
+                        return -ENODEV;
+                }
+        }
+
+        /* Print voltage and multiplier */
+        rdmsr(MSR_IA32_PERF_STATUS, lo, hi);
+        current_voltage = lo & 0xff;
+        printk("eps: Current voltage = %dmV\n", current_voltage * 16 + 700);
+        current_multiplier = (lo >> 8) & 0xff;
+        printk("eps: Current multiplier = %d\n", current_multiplier);
+
+        /* Print limits */
+        max_voltage = hi & 0xff;
+        printk("eps: Highest voltage = %dmV\n", max_voltage * 16 + 700);
+        max_multiplier = (hi >> 8) & 0xff;
+        printk("eps: Highest multiplier = %d\n", max_multiplier);
+        min_voltage = (hi >> 16) & 0xff;
+        printk("eps: Lowest voltage = %dmV\n", min_voltage * 16 + 700);
+        min_multiplier = (hi >> 24) & 0xff;
+        printk("eps: 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 > 0x1c || max_voltage > 0x1c)
+                return -EINVAL;
+        if (max_voltage < min_voltage)
+                return -EINVAL;
+
+        /* Calc FSB speed */
+        fsb = cpu_khz / current_multiplier;
+        /* 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(sizeof(struct eps_cpu_data)
+                    + (states + 1) * sizeof(struct cpufreq_frequency_table),
+                    GFP_KERNEL);
+        if (!centaur)
+                return -ENOMEM;
+        eps_cpu[0] = centaur;
+
+        /* Copy basic values */
+        centaur->fsb = fsb;
+
+        /* Fill frequency and MSR value table */
+        f_table = &centaur->freq_table[0];
+        if (brand == EPS_BRAND_EDEN) {
+                f_table[0].frequency = fsb * min_multiplier;
+                f_table[0].index = (min_multiplier << 8) | min_voltage;
+                f_table[1].frequency = fsb * max_multiplier;
+                f_table[1].index = (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].index = (i << 8) | voltage;
+                        k++;
+                }
+                f_table[k].frequency = CPUFREQ_TABLE_END;
+        }
+
+        policy->governor = CPUFREQ_DEFAULT_GOVERNOR;
+        policy->cpuinfo.transition_latency = 140000; /* 844mV -> 700mV in ns */
+        policy->cur = fsb * current_multiplier;
+
+        ret = cpufreq_frequency_table_cpuinfo(policy, &centaur->freq_table[0]);
+        if (ret) {
+                kfree(centaur);
+                return ret;
+        }
+
+        cpufreq_frequency_table_get_attr(&centaur->freq_table[0], policy->cpu);
+        return 0;
+}
+
+static int eps_cpu_exit(struct cpufreq_policy *policy)
+{
+        unsigned int cpu = policy->cpu;
+        struct eps_cpu_data *centaur;
+        u32 lo, hi;
+
+        if (eps_cpu[cpu] == NULL)
+                return -ENODEV;
+        centaur = eps_cpu[cpu];
+
+        /* Get max frequency */
+        rdmsr(MSR_IA32_PERF_STATUS, lo, hi);
+        /* Set max frequency */
+        eps_set_state(centaur, cpu, hi & 0xffff);
+        /* Bye */
+        cpufreq_frequency_table_put_attr(policy->cpu);
+        kfree(eps_cpu[cpu]);
+        eps_cpu[cpu] = NULL;
+        return 0;
+}
+
+static struct freq_attr* eps_attr[] = {
+        &cpufreq_freq_attr_scaling_available_freqs,
+        NULL,
+};
+
+static struct cpufreq_driver eps_driver = {
+        .verify         = eps_verify,
+        .target         = eps_target,
+        .init           = eps_cpu_init,
+        .exit           = eps_cpu_exit,
+        .get            = eps_get,
+        .name           = "e_powersaver",
+        .owner          = THIS_MODULE,
+        .attr           = eps_attr,
+};
+
+static int __init eps_init(void)
+{
+        struct cpuinfo_x86 *c = cpu_data;
+
+        /* This driver will work only on Centaur C7 processors with
+         * Enhanced SpeedStep/PowerSaver registers */
+        if (c->x86_vendor != X86_VENDOR_CENTAUR
+            || c->x86 != 6 || c->x86_model != 10)
+                return -ENODEV;
+        if (!cpu_has(c, X86_FEATURE_EST))
+                return -ENODEV;
+
+        if (cpufreq_register_driver(&eps_driver))
+                return -EINVAL;
+        return 0;
+}
+
+static void __exit eps_exit(void)
+{
+        cpufreq_unregister_driver(&eps_driver);
+}
+
+MODULE_AUTHOR("Rafał 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);