/*
 * cpufreq driver for Enhanced SpeedStep, as found in Intel's Pentium
 * M (part of the Centrino chipset).
 *
 * Since the original Pentium M, most new Intel CPUs support Enhanced
 * SpeedStep.
 *
 * Despite the "SpeedStep" in the name, this is almost entirely unlike
 * traditional SpeedStep.
 *
 * Modelled on speedstep.c
 *
 * Copyright (C) 2003 Jeremy Fitzhardinge <jeremy@goop.org>
 */

#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/sched.h>        /* current */
#include <linux/delay.h>
#include <linux/compiler.h>
#include <linux/gfp.h>

#include <asm/msr.h>
#include <asm/processor.h>
#include <asm/cpufeature.h>
#include <asm/cpu_device_id.h>

#define MAINTAINER      "linux-pm@vger.kernel.org"

#define INTEL_MSR_RANGE (0xffff)

struct cpu_id
{
        __u8    x86;            /* CPU family */
        __u8    x86_model;      /* model */
        __u8    x86_stepping;   /* stepping */
};

enum {
        CPU_BANIAS,
        CPU_DOTHAN_A1,
        CPU_DOTHAN_A2,
        CPU_DOTHAN_B0,
        CPU_MP4HT_D0,
        CPU_MP4HT_E0,
};

static const struct cpu_id cpu_ids[] = {
        [CPU_BANIAS]    = { 6,  9, 5 },
        [CPU_DOTHAN_A1] = { 6, 13, 1 },
        [CPU_DOTHAN_A2] = { 6, 13, 2 },
        [CPU_DOTHAN_B0] = { 6, 13, 6 },
        [CPU_MP4HT_D0]  = {15,  3, 4 },
        [CPU_MP4HT_E0]  = {15,  4, 1 },
};
#define N_IDS   ARRAY_SIZE(cpu_ids)

struct cpu_model
{
        const struct cpu_id *cpu_id;
        const char      *model_name;
        unsigned        max_freq; /* max clock in kHz */

        struct cpufreq_frequency_table *op_points; /* clock/voltage pairs */
};
static int centrino_verify_cpu_id(const struct cpuinfo_x86 *c,
                                  const struct cpu_id *x);

/* Operating points for current CPU */
static DEFINE_PER_CPU(struct cpu_model *, centrino_model);
static DEFINE_PER_CPU(const struct cpu_id *, centrino_cpu);

static struct cpufreq_driver centrino_driver;

#ifdef CONFIG_X86_SPEEDSTEP_CENTRINO_TABLE

/* Computes the correct form for IA32_PERF_CTL MSR for a particular
   frequency/voltage operating point; frequency in MHz, volts in mV.
   This is stored as "driver_data" in the structure. */
#define OP(mhz, mv)                                                     \
        {                                                               \
                .frequency = (mhz) * 1000,                              \
                .driver_data = (((mhz)/100) << 8) | ((mv - 700) / 16)           \
        }

/*
 * These voltage tables were derived from the Intel Pentium M
 * datasheet, document 25261202.pdf, Table 5.  I have verified they
 * are consistent with my IBM ThinkPad X31, which has a 1.3GHz Pentium
 * M.
 */

/* Ultra Low Voltage Intel Pentium M processor 900MHz (Banias) */
static struct cpufreq_frequency_table banias_900[] =
{
        OP(600,  844),
        OP(800,  988),
        OP(900, 1004),
        { .frequency = CPUFREQ_TABLE_END }
};

/* Ultra Low Voltage Intel Pentium M processor 1000MHz (Banias) */
static struct cpufreq_frequency_table banias_1000[] =
{
        OP(600,   844),
        OP(800,   972),
        OP(900,   988),
        OP(1000, 1004),
        { .frequency = CPUFREQ_TABLE_END }
};

/* Low Voltage Intel Pentium M processor 1.10GHz (Banias) */
static struct cpufreq_frequency_table banias_1100[] =
{
        OP( 600,  956),
        OP( 800, 1020),
        OP( 900, 1100),
        OP(1000, 1164),
        OP(1100, 1180),
        { .frequency = CPUFREQ_TABLE_END }
};


/* Low Voltage Intel Pentium M processor 1.20GHz (Banias) */
static struct cpufreq_frequency_table banias_1200[] =
{
        OP( 600,  956),
        OP( 800, 1004),
        OP( 900, 1020),
        OP(1000, 1100),
        OP(1100, 1164),
        OP(1200, 1180),
        { .frequency = CPUFREQ_TABLE_END }
};

/* Intel Pentium M processor 1.30GHz (Banias) */
static struct cpufreq_frequency_table banias_1300[] =
{
        OP( 600,  956),
        OP( 800, 1260),
        OP(1000, 1292),
        OP(1200, 1356),
        OP(1300, 1388),
        { .frequency = CPUFREQ_TABLE_END }
};

/* Intel Pentium M processor 1.40GHz (Banias) */
static struct cpufreq_frequency_table banias_1400[] =
{
        OP( 600,  956),
        OP( 800, 1180),
        OP(1000, 1308),
        OP(1200, 1436),
        OP(1400, 1484),
        { .frequency = CPUFREQ_TABLE_END }
};

/* Intel Pentium M processor 1.50GHz (Banias) */
static struct cpufreq_frequency_table banias_1500[] =
{
        OP( 600,  956),
        OP( 800, 1116),
        OP(1000, 1228),
        OP(1200, 1356),
        OP(1400, 1452),
        OP(1500, 1484),
        { .frequency = CPUFREQ_TABLE_END }
};

/* Intel Pentium M processor 1.60GHz (Banias) */
static struct cpufreq_frequency_table banias_1600[] =
{
        OP( 600,  956),
        OP( 800, 1036),
        OP(1000, 1164),
        OP(1200, 1276),
        OP(1400, 1420),
        OP(1600, 1484),
        { .frequency = CPUFREQ_TABLE_END }
};

/* Intel Pentium M processor 1.70GHz (Banias) */
static struct cpufreq_frequency_table banias_1700[] =
{
        OP( 600,  956),
        OP( 800, 1004),
        OP(1000, 1116),
        OP(1200, 1228),
        OP(1400, 1308),
        OP(1700, 1484),
        { .frequency = CPUFREQ_TABLE_END }
};
#undef OP

#define _BANIAS(cpuid, max, name)       \
{       .cpu_id         = cpuid,        \
        .model_name     = "Intel(R) Pentium(R) M processor " name "MHz", \
        .max_freq       = (max)*1000,   \
        .op_points      = banias_##max, \
}
#define BANIAS(max)     _BANIAS(&cpu_ids[CPU_BANIAS], max, #max)

/* CPU models, their operating frequency range, and freq/voltage
   operating points */
static struct cpu_model models[] =
{
        _BANIAS(&cpu_ids[CPU_BANIAS], 900, " 900"),
        BANIAS(1000),
        BANIAS(1100),
        BANIAS(1200),
        BANIAS(1300),
        BANIAS(1400),
        BANIAS(1500),
        BANIAS(1600),
        BANIAS(1700),

        /* NULL model_name is a wildcard */
        { &cpu_ids[CPU_DOTHAN_A1], NULL, 0, NULL },
        { &cpu_ids[CPU_DOTHAN_A2], NULL, 0, NULL },
        { &cpu_ids[CPU_DOTHAN_B0], NULL, 0, NULL },
        { &cpu_ids[CPU_MP4HT_D0], NULL, 0, NULL },
        { &cpu_ids[CPU_MP4HT_E0], NULL, 0, NULL },

        { NULL, }
};
#undef _BANIAS
#undef BANIAS

static int centrino_cpu_init_table(struct cpufreq_policy *policy)
{
        struct cpuinfo_x86 *cpu = &cpu_data(policy->cpu);
        struct cpu_model *model;

        for(model = models; model->cpu_id != NULL; model++)
                if (centrino_verify_cpu_id(cpu, model->cpu_id) &&
                    (model->model_name == NULL ||
                     strcmp(cpu->x86_model_id, model->model_name) == 0))
                        break;

        if (model->cpu_id == NULL) {
                /* No match at all */
                pr_debug("no support for CPU model \"%s\": "
                       "send /proc/cpuinfo to " MAINTAINER "\n",
                       cpu->x86_model_id);
                return -ENOENT;
        }

        if (model->op_points == NULL) {
                /* Matched a non-match */
                pr_debug("no table support for CPU model \"%s\"\n",
                       cpu->x86_model_id);
                pr_debug("try using the acpi-cpufreq driver\n");
                return -ENOENT;
        }

        per_cpu(centrino_model, policy->cpu) = model;

        pr_debug("found \"%s\": max frequency: %dkHz\n",
               model->model_name, model->max_freq);

        return 0;
}

#else
static inline int centrino_cpu_init_table(struct cpufreq_policy *policy)
{
        return -ENODEV;
}
#endif /* CONFIG_X86_SPEEDSTEP_CENTRINO_TABLE */

static int centrino_verify_cpu_id(const struct cpuinfo_x86 *c,
                                  const struct cpu_id *x)
{
        if ((c->x86 == x->x86) &&
            (c->x86_model == x->x86_model) &&
            (c->x86_stepping == x->x86_stepping))
                return 1;
        return 0;
}

/* To be called only after centrino_model is initialized */
static unsigned extract_clock(unsigned msr, unsigned int cpu, int failsafe)
{
        int i;

        /*
         * Extract clock in kHz from PERF_CTL value
         * for centrino, as some DSDTs are buggy.
         * Ideally, this can be done using the acpi_data structure.
         */
        if ((per_cpu(centrino_cpu, cpu) == &cpu_ids[CPU_BANIAS]) ||
            (per_cpu(centrino_cpu, cpu) == &cpu_ids[CPU_DOTHAN_A1]) ||
            (per_cpu(centrino_cpu, cpu) == &cpu_ids[CPU_DOTHAN_B0])) {
                msr = (msr >> 8) & 0xff;
                return msr * 100000;
        }

        if ((!per_cpu(centrino_model, cpu)) ||
            (!per_cpu(centrino_model, cpu)->op_points))
                return 0;

        msr &= 0xffff;
        for (i = 0;
                per_cpu(centrino_model, cpu)->op_points[i].frequency
                                                        != CPUFREQ_TABLE_END;
             i++) {
                if (msr == per_cpu(centrino_model, cpu)->op_points[i].driver_data)
                        return per_cpu(centrino_model, cpu)->
                                                        op_points[i].frequency;
        }
        if (failsafe)
                return per_cpu(centrino_model, cpu)->op_points[i-1].frequency;
        else
                return 0;
}

/* Return the current CPU frequency in kHz */
static unsigned int get_cur_freq(unsigned int cpu)
{
        unsigned l, h;
        unsigned clock_freq;

        rdmsr_on_cpu(cpu, MSR_IA32_PERF_STATUS, &l, &h);
        clock_freq = extract_clock(l, cpu, 0);

        if (unlikely(clock_freq == 0)) {
                /*
                 * On some CPUs, we can see transient MSR values (which are
                 * not present in _PSS), while CPU is doing some automatic
                 * P-state transition (like TM2). Get the last freq set 
                 * in PERF_CTL.
                 */
                rdmsr_on_cpu(cpu, MSR_IA32_PERF_CTL, &l, &h);
                clock_freq = extract_clock(l, cpu, 1);
        }
        return clock_freq;
}


static int centrino_cpu_init(struct cpufreq_policy *policy)
{
        struct cpuinfo_x86 *cpu = &cpu_data(policy->cpu);
        unsigned l, h;
        int i;

        /* Only Intel makes Enhanced Speedstep-capable CPUs */
        if (cpu->x86_vendor != X86_VENDOR_INTEL ||
            !cpu_has(cpu, X86_FEATURE_EST))
                return -ENODEV;

        if (cpu_has(cpu, X86_FEATURE_CONSTANT_TSC))
                centrino_driver.flags |= CPUFREQ_CONST_LOOPS;

        if (policy->cpu != 0)
                return -ENODEV;

        for (i = 0; i < N_IDS; i++)
                if (centrino_verify_cpu_id(cpu, &cpu_ids[i]))
                        break;

        if (i != N_IDS)
                per_cpu(centrino_cpu, policy->cpu) = &cpu_ids[i];

        if (!per_cpu(centrino_cpu, policy->cpu)) {
                pr_debug("found unsupported CPU with "
                "Enhanced SpeedStep: send /proc/cpuinfo to "
                MAINTAINER "\n");
                return -ENODEV;
        }

        if (centrino_cpu_init_table(policy))
                return -ENODEV;

        /* Check to see if Enhanced SpeedStep is enabled, and try to
           enable it if not. */
        rdmsr(MSR_IA32_MISC_ENABLE, l, h);

        if (!(l & MSR_IA32_MISC_ENABLE_ENHANCED_SPEEDSTEP)) {
                l |= MSR_IA32_MISC_ENABLE_ENHANCED_SPEEDSTEP;
                pr_debug("trying to enable Enhanced SpeedStep (%x)\n", l);
                wrmsr(MSR_IA32_MISC_ENABLE, l, h);

                /* check to see if it stuck */
                rdmsr(MSR_IA32_MISC_ENABLE, l, h);
                if (!(l & MSR_IA32_MISC_ENABLE_ENHANCED_SPEEDSTEP)) {
                        pr_info("couldn't enable Enhanced SpeedStep\n");
                        return -ENODEV;
                }
        }

        policy->cpuinfo.transition_latency = 10000;
                                                /* 10uS transition latency */
        policy->freq_table = per_cpu(centrino_model, policy->cpu)->op_points;

        return 0;
}

static int centrino_cpu_exit(struct cpufreq_policy *policy)
{
        unsigned int cpu = policy->cpu;

        if (!per_cpu(centrino_model, cpu))
                return -ENODEV;

        per_cpu(centrino_model, cpu) = NULL;

        return 0;
}

/**
 * centrino_setpolicy - set a new CPUFreq policy
 * @policy: new policy
 * @index: index of target frequency
 *
 * Sets a new CPUFreq policy.
 */
static int centrino_target(struct cpufreq_policy *policy, unsigned int index)
{
        unsigned int    msr, oldmsr = 0, h = 0, cpu = policy->cpu;
        int                     retval = 0;
        unsigned int            j, first_cpu;
        struct cpufreq_frequency_table *op_points;
        cpumask_var_t covered_cpus;

        if (unlikely(!zalloc_cpumask_var(&covered_cpus, GFP_KERNEL)))
                return -ENOMEM;

        if (unlikely(per_cpu(centrino_model, cpu) == NULL)) {
                retval = -ENODEV;
                goto out;
        }

        first_cpu = 1;
        op_points = &per_cpu(centrino_model, cpu)->op_points[index];
        for_each_cpu(j, policy->cpus) {
                int good_cpu;

                /*
                 * Support for SMP systems.
                 * Make sure we are running on CPU that wants to change freq
                 */
                if (policy->shared_type == CPUFREQ_SHARED_TYPE_ANY)
                        good_cpu = cpumask_any_and(policy->cpus,
                                                   cpu_online_mask);
                else
                        good_cpu = j;

                if (good_cpu >= nr_cpu_ids) {
                        pr_debug("couldn't limit to CPUs in this domain\n");
                        retval = -EAGAIN;
                        if (first_cpu) {
                                /* We haven't started the transition yet. */
                                goto out;
                        }
                        break;
                }

                msr = op_points->driver_data;

                if (first_cpu) {
                        rdmsr_on_cpu(good_cpu, MSR_IA32_PERF_CTL, &oldmsr, &h);
                        if (msr == (oldmsr & 0xffff)) {
                                pr_debug("no change needed - msr was and needs "
                                        "to be %x\n", oldmsr);
                                retval = 0;
                                goto out;
                        }

                        first_cpu = 0;
                        /* all but 16 LSB are reserved, treat them with care */
                        oldmsr &= ~0xffff;
                        msr &= 0xffff;
                        oldmsr |= msr;
                }

                wrmsr_on_cpu(good_cpu, MSR_IA32_PERF_CTL, oldmsr, h);
                if (policy->shared_type == CPUFREQ_SHARED_TYPE_ANY)
                        break;

                cpumask_set_cpu(j, covered_cpus);
        }

        if (unlikely(retval)) {
                /*
                 * We have failed halfway through the frequency change.
                 * We have sent callbacks to policy->cpus and
                 * MSRs have already been written on coverd_cpus.
                 * Best effort undo..
                 */

                for_each_cpu(j, covered_cpus)
                        wrmsr_on_cpu(j, MSR_IA32_PERF_CTL, oldmsr, h);
        }
        retval = 0;

out:
        free_cpumask_var(covered_cpus);
        return retval;
}

static struct cpufreq_driver centrino_driver = {
        .name           = "centrino", /* should be speedstep-centrino,
                                         but there's a 16 char limit */
        .init           = centrino_cpu_init,
        .exit           = centrino_cpu_exit,
        .verify         = cpufreq_generic_frequency_table_verify,
        .target_index   = centrino_target,
        .get            = get_cur_freq,
        .attr           = cpufreq_generic_attr,
};

/*
 * This doesn't replace the detailed checks above because
 * the generic CPU IDs don't have a way to match for steppings
 * or ASCII model IDs.
 */
static const struct x86_cpu_id centrino_ids[] = {
        { X86_VENDOR_INTEL, 6, 9, X86_FEATURE_EST },
        { X86_VENDOR_INTEL, 6, 13, X86_FEATURE_EST },
        { X86_VENDOR_INTEL, 6, 13, X86_FEATURE_EST },
        { X86_VENDOR_INTEL, 6, 13, X86_FEATURE_EST },
        { X86_VENDOR_INTEL, 15, 3, X86_FEATURE_EST },
        { X86_VENDOR_INTEL, 15, 4, X86_FEATURE_EST },
        {}
};
#if 0
/* Autoload or not? Do not for now. */
MODULE_DEVICE_TABLE(x86cpu, centrino_ids);
#endif

/**
 * centrino_init - initializes the Enhanced SpeedStep CPUFreq driver
 *
 * Initializes the Enhanced SpeedStep support. Returns -ENODEV on
 * unsupported devices, -ENOENT if there's no voltage table for this
 * particular CPU model, -EINVAL on problems during initiatization,
 * and zero on success.
 *
 * This is quite picky.  Not only does the CPU have to advertise the
 * "est" flag in the cpuid capability flags, we look for a specific
 * CPU model and stepping, and we need to have the exact model name in
 * our voltage tables.  That is, be paranoid about not releasing
 * someone's valuable magic smoke.
 */
static int __init centrino_init(void)
{
        if (!x86_match_cpu(centrino_ids))
                return -ENODEV;
        return cpufreq_register_driver(&centrino_driver);
}

static void __exit centrino_exit(void)
{
        cpufreq_unregister_driver(&centrino_driver);
}

MODULE_AUTHOR ("Jeremy Fitzhardinge <jeremy@goop.org>");
MODULE_DESCRIPTION ("Enhanced SpeedStep driver for Intel Pentium M processors.");
MODULE_LICENSE ("GPL");

late_initcall(centrino_init);
module_exit(centrino_exit);