pcc-cpufreq.c

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/*
 *  pcc-cpufreq.c - Processor Clocking Control firmware cpufreq interface
 *
 *  Copyright (C) 2009 Red Hat, Matthew Garrett <[email protected]>
 *  Copyright (C) 2009 Hewlett-Packard Development Company, L.P.
 *  Nagananda Chumbalkar <[email protected]>
 *
 * ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 *
 *  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/slab.h>

#include <linux/acpi.h>
#include <linux/io.h>
#include <linux/spinlock.h>
#include <linux/uaccess.h>

#include <acpi/processor.h>

#define PCC_VERSION "1.10.00"
#define POLL_LOOPS  300

#define CMD_COMPLETE    0x1
#define CMD_GET_FREQ    0x0
#define CMD_SET_FREQ    0x1

#define BUF_SZ      4

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] = {0x9F, 0x2C, 0x9B, 0x63, 0x91, 0x70, 0x1f, 0x49,
              0xBB, 0x4F, 0xA5, 0x98, 0x2F, 0xA1, 0xB5, 0x46};

struct pcc_cpu {
    u32 input_offset;
    u32 output_offset;
};

static struct pcc_cpu __percpu *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);

    pr_debug("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) {
        pr_debug("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);

    pr_debug("get: SUCCESS: (virtual) output_offset for cpu %d is "
        "0x%p, 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) {
        pr_debug("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 0;
}

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);

    pr_debug("target: CPU %d should go to target freq: %d "
        "(virtual) input_offset is 0x%p\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) {
        pr_debug("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);
    pr_debug("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);

    if (!pr)
        return -ENODEV;

    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);

    pr_debug("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;
    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, pcch_handle;
    int ret = 0;

    status = acpi_get_handle(NULL, "\\_SB", &handle);
    if (ACPI_FAILURE(status))
        return -ENODEV;

    status = acpi_get_handle(handle, "PCCH", &pcch_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)
            pr_debug("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;

    pr_debug("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) {
        pr_debug("probe: could not map shared mem region\n");
        ret = -ENOMEM;
        goto out_free;
    }
    pcch_hdr = pcch_virt_addr;

    pr_debug("probe: PCCH header (virtual) addr: 0x%p\n", pcch_hdr);
    pr_debug("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));

    pr_debug("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;

    pr_debug("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;

    pr_debug("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 out;
    }

    result = pcc_get_offset(cpu);
    if (result) {
        pr_debug("init: PCCP evaluation failed\n");
        goto out;
    }

    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);

    if (!policy->cur) {
        pr_debug("init: Unable to get current CPU frequency\n");
        result = -EINVAL;
        goto out;
    }

    pr_debug("init: policy->max is %d, policy->min is %d\n",
        policy->max, policy->min);
out:
    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) {
        pr_debug("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);