3 files changed, 636 insertions, 0 deletions

diff --git a/arch/x86/kernel/cpu/cpufreq/Kconfig b/arch/x86/kernel/cpu/cpufreq/Kconfig
index f138c6c389b9..870e6cc6ad28 100644
--- a/arch/x86/kernel/cpu/cpufreq/Kconfig
+++ b/arch/x86/kernel/cpu/cpufreq/Kconfig
@@ -10,6 +10,20 @@ if CPU_FREQ
 
 comment "CPUFreq processor drivers"
 
+config X86_PCC_CPUFREQ
+        tristate "Processor Clocking Control interface driver"
+        depends on ACPI && ACPI_PROCESSOR
+        help
+          This driver adds support for the PCC interface.
+
+          For details, take a look at:
+          <file:Documentation/cpu-freq/pcc-cpufreq.txt>.
+
+          To compile this driver as a module, choose M here: the
+          module will be called pcc-cpufreq.
+
+          If in doubt, say N.
+
 config X86_ACPI_CPUFREQ
         tristate "ACPI Processor P-States driver"
         select CPU_FREQ_TABLE
diff --git a/arch/x86/kernel/cpu/cpufreq/Makefile b/arch/x86/kernel/cpu/cpufreq/Makefile
index 509296df294d..1840c0a5170b 100644
--- a/arch/x86/kernel/cpu/cpufreq/Makefile
+++ b/arch/x86/kernel/cpu/cpufreq/Makefile
@@ -4,6 +4,7 @@
 
 obj-$(CONFIG_X86_POWERNOW_K8)           += powernow-k8.o
 obj-$(CONFIG_X86_ACPI_CPUFREQ)          += acpi-cpufreq.o
+obj-$(CONFIG_X86_PCC_CPUFREQ)           += pcc-cpufreq.o
 obj-$(CONFIG_X86_POWERNOW_K6)           += powernow-k6.o
 obj-$(CONFIG_X86_POWERNOW_K7)           += powernow-k7.o
 obj-$(CONFIG_X86_LONGHAUL)              += longhaul.o
diff --git a/arch/x86/kernel/cpu/cpufreq/pcc-cpufreq.c b/arch/x86/kernel/cpu/cpufreq/pcc-cpufreq.c
new file mode 100644
index 000000000000..29368854533c
--- /dev/null
+++ b/arch/x86/kernel/cpu/cpufreq/pcc-cpufreq.c
@@ -0,0 +1,621 @@
+/*
+ *  pcc-cpufreq.c - Processor Clocking Control firmware cpufreq interface
+ *
+ *  Copyright (C) 2009 Red Hat, Matthew Garrett <mjg@redhat.com>
+ *  Copyright (C) 2009 Hewlett-Packard Development Company, L.P.
+ *      Nagananda Chumbalkar <nagananda.chumbalkar@hp.com>
+ *
+ * ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+ *
+ *  This program is free software; you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License as published by
+ *  the Free Software Foundation; version 2 of the License.
+ *
+ *  This program is distributed in the hope that it will be useful, but
+ *  WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE, GOOD TITLE or NON
+ *  INFRINGEMENT. See the GNU General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License along
+ *  with this program; if not, write to the Free Software Foundation, Inc.,
+ *  675 Mass Ave, Cambridge, MA 02139, USA.
+ *
+ * ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+ */
+
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/init.h>
+#include <linux/smp.h>
+#include <linux/sched.h>
+#include <linux/cpufreq.h>
+#include <linux/compiler.h>
+
+#include <linux/acpi.h>
+#include <linux/io.h>
+#include <linux/spinlock.h>
+#include <linux/uaccess.h>
+
+#include <acpi/processor.h>
+
+#define PCC_VERSION     "1.00.00"
+#define POLL_LOOPS      300
+
+#define CMD_COMPLETE    0x1
+#define CMD_GET_FREQ    0x0
+#define CMD_SET_FREQ    0x1
+
+#define BUF_SZ          4
+
+#define dprintk(msg...) cpufreq_debug_printk(CPUFREQ_DEBUG_DRIVER,      \
+                                             "pcc-cpufreq", msg)
+
+struct pcc_register_resource {
+        u8 descriptor;
+        u16 length;
+        u8 space_id;
+        u8 bit_width;
+        u8 bit_offset;
+        u8 access_size;
+        u64 address;
+} __attribute__ ((packed));
+
+struct pcc_memory_resource {
+        u8 descriptor;
+        u16 length;
+        u8 space_id;
+        u8 resource_usage;
+        u8 type_specific;
+        u64 granularity;
+        u64 minimum;
+        u64 maximum;
+        u64 translation_offset;
+        u64 address_length;
+} __attribute__ ((packed));
+
+static struct cpufreq_driver pcc_cpufreq_driver;
+
+struct pcc_header {
+        u32 signature;
+        u16 length;
+        u8 major;
+        u8 minor;
+        u32 features;
+        u16 command;
+        u16 status;
+        u32 latency;
+        u32 minimum_time;
+        u32 maximum_time;
+        u32 nominal;
+        u32 throttled_frequency;
+        u32 minimum_frequency;
+};
+
+static void __iomem *pcch_virt_addr;
+static struct pcc_header __iomem *pcch_hdr;
+
+static DEFINE_SPINLOCK(pcc_lock);
+
+static struct acpi_generic_address doorbell;
+
+static u64 doorbell_preserve;
+static u64 doorbell_write;
+
+static u8 OSC_UUID[16] = {0x63, 0x9B, 0x2C, 0x9F, 0x70, 0x91, 0x49, 0x1f,
+                          0xBB, 0x4F, 0xA5, 0x98, 0x2F, 0xA1, 0xB5, 0x46};
+
+struct pcc_cpu {
+        u32 input_offset;
+        u32 output_offset;
+};
+
+static struct pcc_cpu *pcc_cpu_info;
+
+static int pcc_cpufreq_verify(struct cpufreq_policy *policy)
+{
+        cpufreq_verify_within_limits(policy, policy->cpuinfo.min_freq,
+                                     policy->cpuinfo.max_freq);
+        return 0;
+}
+
+static inline void pcc_cmd(void)
+{
+        u64 doorbell_value;
+        int i;
+
+        acpi_read(&doorbell_value, &doorbell);
+        acpi_write((doorbell_value & doorbell_preserve) | doorbell_write,
+                   &doorbell);
+
+        for (i = 0; i < POLL_LOOPS; i++) {
+                if (ioread16(&pcch_hdr->status) & CMD_COMPLETE)
+                        break;
+        }
+}
+
+static inline void pcc_clear_mapping(void)
+{
+        if (pcch_virt_addr)
+                iounmap(pcch_virt_addr);
+        pcch_virt_addr = NULL;
+}
+
+static unsigned int pcc_get_freq(unsigned int cpu)
+{
+        struct pcc_cpu *pcc_cpu_data;
+        unsigned int curr_freq;
+        unsigned int freq_limit;
+        u16 status;
+        u32 input_buffer;
+        u32 output_buffer;
+
+        spin_lock(&pcc_lock);
+
+        dprintk("get: get_freq for CPU %d\n", cpu);
+        pcc_cpu_data = per_cpu_ptr(pcc_cpu_info, cpu);
+
+        input_buffer = 0x1;
+        iowrite32(input_buffer,
+                        (pcch_virt_addr + pcc_cpu_data->input_offset));
+        iowrite16(CMD_GET_FREQ, &pcch_hdr->command);
+
+        pcc_cmd();
+
+        output_buffer =
+                ioread32(pcch_virt_addr + pcc_cpu_data->output_offset);
+
+        /* Clear the input buffer - we are done with the current command */
+        memset_io((pcch_virt_addr + pcc_cpu_data->input_offset), 0, BUF_SZ);
+
+        status = ioread16(&pcch_hdr->status);
+        if (status != CMD_COMPLETE) {
+                dprintk("get: FAILED: for CPU %d, status is %d\n",
+                        cpu, status);
+                goto cmd_incomplete;
+        }
+        iowrite16(0, &pcch_hdr->status);
+        curr_freq = (((ioread32(&pcch_hdr->nominal) * (output_buffer & 0xff))
+                        / 100) * 1000);
+
+        dprintk("get: SUCCESS: (virtual) output_offset for cpu %d is "
+                "0x%x, contains a value of: 0x%x. Speed is: %d MHz\n",
+                cpu, (pcch_virt_addr + pcc_cpu_data->output_offset),
+                output_buffer, curr_freq);
+
+        freq_limit = (output_buffer >> 8) & 0xff;
+        if (freq_limit != 0xff) {
+                dprintk("get: frequency for cpu %d is being temporarily"
+                        " capped at %d\n", cpu, curr_freq);
+        }
+
+        spin_unlock(&pcc_lock);
+        return curr_freq;
+
+cmd_incomplete:
+        iowrite16(0, &pcch_hdr->status);
+        spin_unlock(&pcc_lock);
+        return -EINVAL;
+}
+
+static int pcc_cpufreq_target(struct cpufreq_policy *policy,
+                              unsigned int target_freq,
+                              unsigned int relation)
+{
+        struct pcc_cpu *pcc_cpu_data;
+        struct cpufreq_freqs freqs;
+        u16 status;
+        u32 input_buffer;
+        int cpu;
+
+        spin_lock(&pcc_lock);
+        cpu = policy->cpu;
+        pcc_cpu_data = per_cpu_ptr(pcc_cpu_info, cpu);
+
+        dprintk("target: CPU %d should go to target freq: %d "
+                "(virtual) input_offset is 0x%x\n",
+                cpu, target_freq,
+                (pcch_virt_addr + pcc_cpu_data->input_offset));
+
+        freqs.new = target_freq;
+        freqs.cpu = cpu;
+        cpufreq_notify_transition(&freqs, CPUFREQ_PRECHANGE);
+
+        input_buffer = 0x1 | (((target_freq * 100)
+                               / (ioread32(&pcch_hdr->nominal) * 1000)) << 8);
+        iowrite32(input_buffer,
+                        (pcch_virt_addr + pcc_cpu_data->input_offset));
+        iowrite16(CMD_SET_FREQ, &pcch_hdr->command);
+
+        pcc_cmd();
+
+        /* Clear the input buffer - we are done with the current command */
+        memset_io((pcch_virt_addr + pcc_cpu_data->input_offset), 0, BUF_SZ);
+
+        status = ioread16(&pcch_hdr->status);
+        if (status != CMD_COMPLETE) {
+                dprintk("target: FAILED for cpu %d, with status: 0x%x\n",
+                        cpu, status);
+                goto cmd_incomplete;
+        }
+        iowrite16(0, &pcch_hdr->status);
+
+        cpufreq_notify_transition(&freqs, CPUFREQ_POSTCHANGE);
+        dprintk("target: was SUCCESSFUL for cpu %d\n", cpu);
+        spin_unlock(&pcc_lock);
+
+        return 0;
+
+cmd_incomplete:
+        iowrite16(0, &pcch_hdr->status);
+        spin_unlock(&pcc_lock);
+        return -EINVAL;
+}
+
+static int pcc_get_offset(int cpu)
+{
+        acpi_status status;
+        struct acpi_buffer buffer = {ACPI_ALLOCATE_BUFFER, NULL};
+        union acpi_object *pccp, *offset;
+        struct pcc_cpu *pcc_cpu_data;
+        struct acpi_processor *pr;
+        int ret = 0;
+
+        pr = per_cpu(processors, cpu);
+        pcc_cpu_data = per_cpu_ptr(pcc_cpu_info, cpu);
+
+        status = acpi_evaluate_object(pr->handle, "PCCP", NULL, &buffer);
+        if (ACPI_FAILURE(status))
+                return -ENODEV;
+
+        pccp = buffer.pointer;
+        if (!pccp || pccp->type != ACPI_TYPE_PACKAGE) {
+                ret = -ENODEV;
+                goto out_free;
+        };
+
+        offset = &(pccp->package.elements[0]);
+        if (!offset || offset->type != ACPI_TYPE_INTEGER) {
+                ret = -ENODEV;
+                goto out_free;
+        }
+
+        pcc_cpu_data->input_offset = offset->integer.value;
+
+        offset = &(pccp->package.elements[1]);
+        if (!offset || offset->type != ACPI_TYPE_INTEGER) {
+                ret = -ENODEV;
+                goto out_free;
+        }
+
+        pcc_cpu_data->output_offset = offset->integer.value;
+
+        memset_io((pcch_virt_addr + pcc_cpu_data->input_offset), 0, BUF_SZ);
+        memset_io((pcch_virt_addr + pcc_cpu_data->output_offset), 0, BUF_SZ);
+
+        dprintk("pcc_get_offset: for CPU %d: pcc_cpu_data "
+                "input_offset: 0x%x, pcc_cpu_data output_offset: 0x%x\n",
+                cpu, pcc_cpu_data->input_offset, pcc_cpu_data->output_offset);
+out_free:
+        kfree(buffer.pointer);
+        return ret;
+}
+
+static int __init pcc_cpufreq_do_osc(acpi_handle *handle)
+{
+        acpi_status status;
+        struct acpi_object_list input;
+        struct acpi_buffer output = {ACPI_ALLOCATE_BUFFER, NULL};
+        union acpi_object in_params[4];
+        union acpi_object *out_obj;
+        u32 capabilities[2];
+        u32 errors;
+        u32 supported;
+        int ret = 0;
+
+        input.count = 4;
+        input.pointer = in_params;
+        input.count = 4;
+        input.pointer = in_params;
+        in_params[0].type               = ACPI_TYPE_BUFFER;
+        in_params[0].buffer.length      = 16;
+        in_params[0].buffer.pointer     = OSC_UUID;
+        in_params[1].type               = ACPI_TYPE_INTEGER;
+        in_params[1].integer.value      = 1;
+        in_params[2].type               = ACPI_TYPE_INTEGER;
+        in_params[2].integer.value      = 2;
+        in_params[3].type               = ACPI_TYPE_BUFFER;
+        in_params[3].buffer.length      = 8;
+        in_params[3].buffer.pointer     = (u8 *)&capabilities;
+
+        capabilities[0] = OSC_QUERY_ENABLE;
+        capabilities[1] = 0x1;
+
+        status = acpi_evaluate_object(*handle, "_OSC", &input, &output);
+        if (ACPI_FAILURE(status))
+                return -ENODEV;
+
+        if (!output.length)
+                return -ENODEV;
+
+        out_obj = output.pointer;
+        if (out_obj->type != ACPI_TYPE_BUFFER) {
+                ret = -ENODEV;
+                goto out_free;
+        }
+
+        errors = *((u32 *)out_obj->buffer.pointer) & ~(1 << 0);
+        if (errors) {
+                ret = -ENODEV;
+                goto out_free;
+        }
+
+        supported = *((u32 *)(out_obj->buffer.pointer + 4));
+        if (!(supported & 0x1)) {
+                ret = -ENODEV;
+                goto out_free;
+        }
+
+        kfree(output.pointer);
+        capabilities[0] = 0x0;
+        capabilities[1] = 0x1;
+
+        status = acpi_evaluate_object(*handle, "_OSC", &input, &output);
+        if (ACPI_FAILURE(status))
+                return -ENODEV;
+
+        if (!output.length)
+                return -ENODEV;
+
+        out_obj = output.pointer;
+        if (out_obj->type != ACPI_TYPE_BUFFER) {
+                ret = -ENODEV;
+                goto out_free;
+        }
+
+        errors = *((u32 *)out_obj->buffer.pointer) & ~(1 << 0);
+        if (errors) {
+                ret = -ENODEV;
+                goto out_free;
+        }
+
+        supported = *((u32 *)(out_obj->buffer.pointer + 4));
+        if (!(supported & 0x1)) {
+                ret = -ENODEV;
+                goto out_free;
+        }
+
+out_free:
+        kfree(output.pointer);
+        return ret;
+}
+
+static int __init pcc_cpufreq_probe(void)
+{
+        acpi_status status;
+        struct acpi_buffer output = {ACPI_ALLOCATE_BUFFER, NULL};
+        struct pcc_memory_resource *mem_resource;
+        struct pcc_register_resource *reg_resource;
+        union acpi_object *out_obj, *member;
+        acpi_handle handle, osc_handle;
+        int ret = 0;
+
+        status = acpi_get_handle(NULL, "\\_SB", &handle);
+        if (ACPI_FAILURE(status))
+                return -ENODEV;
+
+        status = acpi_get_handle(handle, "_OSC", &osc_handle);
+        if (ACPI_SUCCESS(status)) {
+                ret = pcc_cpufreq_do_osc(&osc_handle);
+                if (ret)
+                        dprintk("probe: _OSC evaluation did not succeed\n");
+                /* Firmware's use of _OSC is optional */
+                ret = 0;
+        }
+
+        status = acpi_evaluate_object(handle, "PCCH", NULL, &output);
+        if (ACPI_FAILURE(status))
+                return -ENODEV;
+
+        out_obj = output.pointer;
+        if (out_obj->type != ACPI_TYPE_PACKAGE) {
+                ret = -ENODEV;
+                goto out_free;
+        }
+
+        member = &out_obj->package.elements[0];
+        if (member->type != ACPI_TYPE_BUFFER) {
+                ret = -ENODEV;
+                goto out_free;
+        }
+
+        mem_resource = (struct pcc_memory_resource *)member->buffer.pointer;
+
+        dprintk("probe: mem_resource descriptor: 0x%x,"
+                " length: %d, space_id: %d, resource_usage: %d,"
+                " type_specific: %d, granularity: 0x%llx,"
+                " minimum: 0x%llx, maximum: 0x%llx,"
+                " translation_offset: 0x%llx, address_length: 0x%llx\n",
+                mem_resource->descriptor, mem_resource->length,
+                mem_resource->space_id, mem_resource->resource_usage,
+                mem_resource->type_specific, mem_resource->granularity,
+                mem_resource->minimum, mem_resource->maximum,
+                mem_resource->translation_offset,
+                mem_resource->address_length);
+
+        if (mem_resource->space_id != ACPI_ADR_SPACE_SYSTEM_MEMORY) {
+                ret = -ENODEV;
+                goto out_free;
+        }
+
+        pcch_virt_addr = ioremap_nocache(mem_resource->minimum,
+                                        mem_resource->address_length);
+        if (pcch_virt_addr == NULL) {
+                dprintk("probe: could not map shared mem region\n");
+                goto out_free;
+        }
+        pcch_hdr = pcch_virt_addr;
+
+        dprintk("probe: PCCH header (virtual) addr: 0x%llx\n",
+                (u64)pcch_hdr);
+        dprintk("probe: PCCH header is at physical address: 0x%llx,"
+                " signature: 0x%x, length: %d bytes, major: %d, minor: %d,"
+                " supported features: 0x%x, command field: 0x%x,"
+                " status field: 0x%x, nominal latency: %d us\n",
+                mem_resource->minimum, ioread32(&pcch_hdr->signature),
+                ioread16(&pcch_hdr->length), ioread8(&pcch_hdr->major),
+                ioread8(&pcch_hdr->minor), ioread32(&pcch_hdr->features),
+                ioread16(&pcch_hdr->command), ioread16(&pcch_hdr->status),
+                ioread32(&pcch_hdr->latency));
+
+        dprintk("probe: min time between commands: %d us,"
+                " max time between commands: %d us,"
+                " nominal CPU frequency: %d MHz,"
+                " minimum CPU frequency: %d MHz,"
+                " minimum CPU frequency without throttling: %d MHz\n",
+                ioread32(&pcch_hdr->minimum_time),
+                ioread32(&pcch_hdr->maximum_time),
+                ioread32(&pcch_hdr->nominal),
+                ioread32(&pcch_hdr->throttled_frequency),
+                ioread32(&pcch_hdr->minimum_frequency));
+
+        member = &out_obj->package.elements[1];
+        if (member->type != ACPI_TYPE_BUFFER) {
+                ret = -ENODEV;
+                goto pcch_free;
+        }
+
+        reg_resource = (struct pcc_register_resource *)member->buffer.pointer;
+
+        doorbell.space_id = reg_resource->space_id;
+        doorbell.bit_width = reg_resource->bit_width;
+        doorbell.bit_offset = reg_resource->bit_offset;
+        doorbell.access_width = 64;
+        doorbell.address = reg_resource->address;
+
+        dprintk("probe: doorbell: space_id is %d, bit_width is %d, "
+                "bit_offset is %d, access_width is %d, address is 0x%llx\n",
+                doorbell.space_id, doorbell.bit_width, doorbell.bit_offset,
+                doorbell.access_width, reg_resource->address);
+
+        member = &out_obj->package.elements[2];
+        if (member->type != ACPI_TYPE_INTEGER) {
+                ret = -ENODEV;
+                goto pcch_free;
+        }
+
+        doorbell_preserve = member->integer.value;
+
+        member = &out_obj->package.elements[3];
+        if (member->type != ACPI_TYPE_INTEGER) {
+                ret = -ENODEV;
+                goto pcch_free;
+        }
+
+        doorbell_write = member->integer.value;
+
+        dprintk("probe: doorbell_preserve: 0x%llx,"
+                " doorbell_write: 0x%llx\n",
+                doorbell_preserve, doorbell_write);
+
+        pcc_cpu_info = alloc_percpu(struct pcc_cpu);
+        if (!pcc_cpu_info) {
+                ret = -ENOMEM;
+                goto pcch_free;
+        }
+
+        printk(KERN_DEBUG "pcc-cpufreq: (v%s) driver loaded with frequency"
+               " limits: %d MHz, %d MHz\n", PCC_VERSION,
+               ioread32(&pcch_hdr->minimum_frequency),
+               ioread32(&pcch_hdr->nominal));
+        kfree(output.pointer);
+        return ret;
+pcch_free:
+        pcc_clear_mapping();
+out_free:
+        kfree(output.pointer);
+        return ret;
+}
+
+static int pcc_cpufreq_cpu_init(struct cpufreq_policy *policy)
+{
+        unsigned int cpu = policy->cpu;
+        unsigned int result = 0;
+
+        if (!pcch_virt_addr) {
+                result = -1;
+                goto pcch_null;
+        }
+
+        result = pcc_get_offset(cpu);
+        if (result) {
+                dprintk("init: PCCP evaluation failed\n");
+                goto free;
+        }
+
+        policy->max = policy->cpuinfo.max_freq =
+                ioread32(&pcch_hdr->nominal) * 1000;
+        policy->min = policy->cpuinfo.min_freq =
+                ioread32(&pcch_hdr->minimum_frequency) * 1000;
+        policy->cur = pcc_get_freq(cpu);
+
+        dprintk("init: policy->max is %d, policy->min is %d\n",
+                policy->max, policy->min);
+
+        return 0;
+free:
+        pcc_clear_mapping();
+        free_percpu(pcc_cpu_info);
+pcch_null:
+        return result;
+}
+
+static int pcc_cpufreq_cpu_exit(struct cpufreq_policy *policy)
+{
+        return 0;
+}
+
+static struct cpufreq_driver pcc_cpufreq_driver = {
+        .flags = CPUFREQ_CONST_LOOPS,
+        .get = pcc_get_freq,
+        .verify = pcc_cpufreq_verify,
+        .target = pcc_cpufreq_target,
+        .init = pcc_cpufreq_cpu_init,
+        .exit = pcc_cpufreq_cpu_exit,
+        .name = "pcc-cpufreq",
+        .owner = THIS_MODULE,
+};
+
+static int __init pcc_cpufreq_init(void)
+{
+        int ret;
+
+        if (acpi_disabled)
+                return 0;
+
+        ret = pcc_cpufreq_probe();
+        if (ret) {
+                dprintk("pcc_cpufreq_init: PCCH evaluation failed\n");
+                return ret;
+        }
+
+        ret = cpufreq_register_driver(&pcc_cpufreq_driver);
+
+        return ret;
+}
+
+static void __exit pcc_cpufreq_exit(void)
+{
+        cpufreq_unregister_driver(&pcc_cpufreq_driver);
+
+        pcc_clear_mapping();
+
+        free_percpu(pcc_cpu_info);
+}
+
+MODULE_AUTHOR("Matthew Garrett, Naga Chumbalkar");
+MODULE_VERSION(PCC_VERSION);
+MODULE_DESCRIPTION("Processor Clocking Control interface driver");
+MODULE_LICENSE("GPL");
+
+late_initcall(pcc_cpufreq_init);
+module_exit(pcc_cpufreq_exit);