// SPDX-License-Identifier: GPL-2.0-only
/*
 * CPPC (Collaborative Processor Performance Control) driver for
 * interfacing with the CPUfreq layer and governors. See
 * cppc_acpi.c for CPPC specific methods.
 *
 * (C) Copyright 2014, 2015 Linaro Ltd.
 * Author: Ashwin Chaugule <ashwin.chaugule@linaro.org>
 */

#define pr_fmt(fmt)     "CPPC Cpufreq:" fmt

#include <linux/arch_topology.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/delay.h>
#include <linux/cpu.h>
#include <linux/cpufreq.h>
#include <linux/irq_work.h>
#include <linux/kthread.h>
#include <linux/time.h>
#include <linux/vmalloc.h>
#include <uapi/linux/sched/types.h>

#include <linux/unaligned.h>

#include <acpi/cppc_acpi.h>

static struct cpufreq_driver cppc_cpufreq_driver;

#ifdef CONFIG_ACPI_CPPC_CPUFREQ_FIE
static enum {
        FIE_UNSET = -1,
        FIE_ENABLED,
        FIE_DISABLED
} fie_disabled = FIE_UNSET;

module_param(fie_disabled, int, 0444);
MODULE_PARM_DESC(fie_disabled, "Disable Frequency Invariance Engine (FIE)");

/* Frequency invariance support */
struct cppc_freq_invariance {
        int cpu;
        struct irq_work irq_work;
        struct kthread_work work;
        struct cppc_perf_fb_ctrs prev_perf_fb_ctrs;
        struct cppc_cpudata *cpu_data;
};

static DEFINE_PER_CPU(struct cppc_freq_invariance, cppc_freq_inv);
static struct kthread_worker *kworker_fie;

static int cppc_perf_from_fbctrs(struct cppc_perf_fb_ctrs *fb_ctrs_t0,
                                 struct cppc_perf_fb_ctrs *fb_ctrs_t1);

/**
 * __cppc_scale_freq_tick - CPPC arch_freq_scale updater for frequency invariance
 * @cppc_fi: per-cpu CPPC FIE data.
 *
 * The CPPC driver registers itself with the topology core to provide its own
 * implementation (cppc_scale_freq_tick()) of topology_scale_freq_tick() which
 * gets called by the scheduler on every tick.
 *
 * Note that the arch specific counters have higher priority than CPPC counters,
 * if available, though the CPPC driver doesn't need to have any special
 * handling for that.
 */
static void __cppc_scale_freq_tick(struct cppc_freq_invariance *cppc_fi)
{
        struct cppc_perf_fb_ctrs fb_ctrs = {0};
        struct cppc_cpudata *cpu_data;
        unsigned long local_freq_scale;
        u64 perf;

        cpu_data = cppc_fi->cpu_data;

        if (cppc_get_perf_ctrs(cppc_fi->cpu, &fb_ctrs)) {
                pr_warn("%s: failed to read perf counters\n", __func__);
                return;
        }

        perf = cppc_perf_from_fbctrs(&cppc_fi->prev_perf_fb_ctrs, &fb_ctrs);
        if (!perf)
                return;

        cppc_fi->prev_perf_fb_ctrs = fb_ctrs;

        perf <<= SCHED_CAPACITY_SHIFT;
        local_freq_scale = div64_u64(perf, cpu_data->perf_caps.highest_perf);

        /* This can happen due to counter's overflow */
        if (unlikely(local_freq_scale > 1024))
                local_freq_scale = 1024;

        per_cpu(arch_freq_scale, cppc_fi->cpu) = local_freq_scale;
}

static void cppc_scale_freq_tick(void)
{
        __cppc_scale_freq_tick(&per_cpu(cppc_freq_inv, smp_processor_id()));
}

static struct scale_freq_data cppc_sftd = {
        .source = SCALE_FREQ_SOURCE_CPPC,
        .set_freq_scale = cppc_scale_freq_tick,
};

static void cppc_scale_freq_workfn(struct kthread_work *work)
{
        struct cppc_freq_invariance *cppc_fi;

        cppc_fi = container_of(work, struct cppc_freq_invariance, work);
        __cppc_scale_freq_tick(cppc_fi);
}

static void cppc_irq_work(struct irq_work *irq_work)
{
        struct cppc_freq_invariance *cppc_fi;

        cppc_fi = container_of(irq_work, struct cppc_freq_invariance, irq_work);
        kthread_queue_work(kworker_fie, &cppc_fi->work);
}

/*
 * Reading perf counters may sleep if the CPC regs are in PCC.  Thus, we
 * schedule an irq work in scale_freq_tick (since we reach here from hard-irq
 * context), which then schedules a normal work item cppc_scale_freq_workfn()
 * that updates the per_cpu arch_freq_scale variable based on the counter
 * updates since the last tick.
 */
static void cppc_scale_freq_tick_pcc(void)
{
        struct cppc_freq_invariance *cppc_fi = &per_cpu(cppc_freq_inv, smp_processor_id());

        /*
         * cppc_get_perf_ctrs() can potentially sleep, call that from the right
         * context.
         */
        irq_work_queue(&cppc_fi->irq_work);
}

static struct scale_freq_data cppc_sftd_pcc = {
        .source = SCALE_FREQ_SOURCE_CPPC,
        .set_freq_scale = cppc_scale_freq_tick_pcc,
};

static void cppc_cpufreq_cpu_fie_init(struct cpufreq_policy *policy)
{
        struct scale_freq_data *sftd = &cppc_sftd;
        struct cppc_freq_invariance *cppc_fi;
        int cpu, ret;

        if (fie_disabled)
                return;

        for_each_cpu(cpu, policy->cpus) {
                cppc_fi = &per_cpu(cppc_freq_inv, cpu);
                cppc_fi->cpu = cpu;
                cppc_fi->cpu_data = policy->driver_data;
                if (cppc_perf_ctrs_in_pcc_cpu(cpu)) {
                        kthread_init_work(&cppc_fi->work, cppc_scale_freq_workfn);
                        init_irq_work(&cppc_fi->irq_work, cppc_irq_work);
                        sftd = &cppc_sftd_pcc;
                }

                ret = cppc_get_perf_ctrs(cpu, &cppc_fi->prev_perf_fb_ctrs);

                /*
                 * Don't abort as the CPU was offline while the driver was
                 * getting registered.
                 */
                if (ret && cpu_online(cpu)) {
                        pr_debug("%s: failed to read perf counters for cpu:%d: %d\n",
                                __func__, cpu, ret);
                        return;
                }
        }

        /* Register for freq-invariance */
        topology_set_scale_freq_source(sftd, policy->cpus);
}

/*
 * We free all the resources on policy's removal and not on CPU removal as the
 * irq-work are per-cpu and the hotplug core takes care of flushing the pending
 * irq-works (hint: smpcfd_dying_cpu()) on CPU hotplug. Even if the kthread-work
 * fires on another CPU after the concerned CPU is removed, it won't harm.
 *
 * We just need to make sure to remove them all on policy->exit().
 */
static void cppc_cpufreq_cpu_fie_exit(struct cpufreq_policy *policy)
{
        struct cppc_freq_invariance *cppc_fi;
        int cpu;

        if (fie_disabled)
                return;

        /* policy->cpus will be empty here, use related_cpus instead */
        topology_clear_scale_freq_source(SCALE_FREQ_SOURCE_CPPC, policy->related_cpus);

        for_each_cpu(cpu, policy->related_cpus) {
                if (!cppc_perf_ctrs_in_pcc_cpu(cpu))
                        continue;
                cppc_fi = &per_cpu(cppc_freq_inv, cpu);
                irq_work_sync(&cppc_fi->irq_work);
                kthread_cancel_work_sync(&cppc_fi->work);
        }
}

static void cppc_fie_kworker_init(void)
{
        struct sched_attr attr = {
                .size           = sizeof(struct sched_attr),
                .sched_policy   = SCHED_DEADLINE,
                .sched_nice     = 0,
                .sched_priority = 0,
                /*
                 * Fake (unused) bandwidth; workaround to "fix"
                 * priority inheritance.
                 */
                .sched_runtime  = NSEC_PER_MSEC,
                .sched_deadline = 10 * NSEC_PER_MSEC,
                .sched_period   = 10 * NSEC_PER_MSEC,
        };
        int ret;

        kworker_fie = kthread_run_worker(0, "cppc_fie");
        if (IS_ERR(kworker_fie)) {
                pr_warn("%s: failed to create kworker_fie: %ld\n", __func__,
                        PTR_ERR(kworker_fie));
                fie_disabled = FIE_DISABLED;
                kworker_fie = NULL;
                return;
        }

        ret = sched_setattr_nocheck(kworker_fie->task, &attr);
        if (ret) {
                pr_warn("%s: failed to set SCHED_DEADLINE: %d\n", __func__,
                        ret);
                kthread_destroy_worker(kworker_fie);
                fie_disabled = FIE_DISABLED;
                kworker_fie = NULL;
        }
}

static void __init cppc_freq_invariance_init(void)
{
        bool perf_ctrs_in_pcc = cppc_perf_ctrs_in_pcc();

        if (fie_disabled == FIE_UNSET) {
                if (perf_ctrs_in_pcc) {
                        pr_info("FIE not enabled on systems with registers in PCC\n");
                        fie_disabled = FIE_DISABLED;
                } else {
                        fie_disabled = FIE_ENABLED;
                }
        }

        if (fie_disabled || !perf_ctrs_in_pcc)
                return;

        cppc_fie_kworker_init();
}

static void cppc_freq_invariance_exit(void)
{
        if (kworker_fie)
                kthread_destroy_worker(kworker_fie);
}

#else
static inline void cppc_cpufreq_cpu_fie_init(struct cpufreq_policy *policy)
{
}

static inline void cppc_cpufreq_cpu_fie_exit(struct cpufreq_policy *policy)
{
}

static inline void cppc_freq_invariance_init(void)
{
}

static inline void cppc_freq_invariance_exit(void)
{
}
#endif /* CONFIG_ACPI_CPPC_CPUFREQ_FIE */

static int cppc_cpufreq_set_target(struct cpufreq_policy *policy,
                                   unsigned int target_freq,
                                   unsigned int relation)
{
        struct cppc_cpudata *cpu_data = policy->driver_data;
        unsigned int cpu = policy->cpu;
        struct cpufreq_freqs freqs;
        int ret = 0;

        cpu_data->perf_ctrls.desired_perf =
                        cppc_khz_to_perf(&cpu_data->perf_caps, target_freq);
        freqs.old = policy->cur;
        freqs.new = target_freq;

        cpufreq_freq_transition_begin(policy, &freqs);
        ret = cppc_set_perf(cpu, &cpu_data->perf_ctrls);
        cpufreq_freq_transition_end(policy, &freqs, ret != 0);

        if (ret)
                pr_debug("Failed to set target on CPU:%d. ret:%d\n",
                         cpu, ret);

        return ret;
}

static unsigned int cppc_cpufreq_fast_switch(struct cpufreq_policy *policy,
                                              unsigned int target_freq)
{
        struct cppc_cpudata *cpu_data = policy->driver_data;
        unsigned int cpu = policy->cpu;
        u32 desired_perf;
        int ret;

        desired_perf = cppc_khz_to_perf(&cpu_data->perf_caps, target_freq);
        cpu_data->perf_ctrls.desired_perf = desired_perf;
        ret = cppc_set_perf(cpu, &cpu_data->perf_ctrls);

        if (ret) {
                pr_debug("Failed to set target on CPU:%d. ret:%d\n",
                         cpu, ret);
                return 0;
        }

        return target_freq;
}

static int cppc_verify_policy(struct cpufreq_policy_data *policy)
{
        cpufreq_verify_within_cpu_limits(policy);
        return 0;
}

static unsigned int __cppc_cpufreq_get_transition_delay_us(unsigned int cpu)
{
        int transition_latency_ns = cppc_get_transition_latency(cpu);

        if (transition_latency_ns < 0)
                return CPUFREQ_DEFAULT_TRANSITION_LATENCY_NS / NSEC_PER_USEC;

        return transition_latency_ns / NSEC_PER_USEC;
}

/*
 * The PCC subspace describes the rate at which platform can accept commands
 * on the shared PCC channel (including READs which do not count towards freq
 * transition requests), so ideally we need to use the PCC values as a fallback
 * if we don't have a platform specific transition_delay_us
 */
#ifdef CONFIG_ARM64
#include <asm/cputype.h>

static unsigned int cppc_cpufreq_get_transition_delay_us(unsigned int cpu)
{
        unsigned long implementor = read_cpuid_implementor();
        unsigned long part_num = read_cpuid_part_number();

        switch (implementor) {
        case ARM_CPU_IMP_QCOM:
                switch (part_num) {
                case QCOM_CPU_PART_FALKOR_V1:
                case QCOM_CPU_PART_FALKOR:
                        return 10000;
                }
        }
        return __cppc_cpufreq_get_transition_delay_us(cpu);
}
#else
static unsigned int cppc_cpufreq_get_transition_delay_us(unsigned int cpu)
{
        return __cppc_cpufreq_get_transition_delay_us(cpu);
}
#endif

#if defined(CONFIG_ARM64) && defined(CONFIG_ENERGY_MODEL)

static DEFINE_PER_CPU(unsigned int, efficiency_class);

/* Create an artificial performance state every CPPC_EM_CAP_STEP capacity unit. */
#define CPPC_EM_CAP_STEP        (20)
/* Increase the cost value by CPPC_EM_COST_STEP every performance state. */
#define CPPC_EM_COST_STEP       (1)
/* Add a cost gap correspnding to the energy of 4 CPUs. */
#define CPPC_EM_COST_GAP        (4 * SCHED_CAPACITY_SCALE * CPPC_EM_COST_STEP \
                                / CPPC_EM_CAP_STEP)

static unsigned int get_perf_level_count(struct cpufreq_policy *policy)
{
        struct cppc_perf_caps *perf_caps;
        unsigned int min_cap, max_cap;
        struct cppc_cpudata *cpu_data;
        int cpu = policy->cpu;

        cpu_data = policy->driver_data;
        perf_caps = &cpu_data->perf_caps;
        max_cap = arch_scale_cpu_capacity(cpu);
        min_cap = div_u64((u64)max_cap * perf_caps->lowest_perf,
                          perf_caps->highest_perf);
        if ((min_cap == 0) || (max_cap < min_cap))
                return 0;
        return 1 + max_cap / CPPC_EM_CAP_STEP - min_cap / CPPC_EM_CAP_STEP;
}

/*
 * The cost is defined as:
 *   cost = power * max_frequency / frequency
 */
static inline unsigned long compute_cost(int cpu, int step)
{
        return CPPC_EM_COST_GAP * per_cpu(efficiency_class, cpu) +
                        step * CPPC_EM_COST_STEP;
}

static int cppc_get_cpu_power(struct device *cpu_dev,
                unsigned long *power, unsigned long *KHz)
{
        unsigned long perf_step, perf_prev, perf, perf_check;
        unsigned int min_step, max_step, step, step_check;
        unsigned long prev_freq = *KHz;
        unsigned int min_cap, max_cap;
        struct cpufreq_policy *policy;

        struct cppc_perf_caps *perf_caps;
        struct cppc_cpudata *cpu_data;

        policy = cpufreq_cpu_get_raw(cpu_dev->id);
        if (!policy)
                return -EINVAL;

        cpu_data = policy->driver_data;
        perf_caps = &cpu_data->perf_caps;
        max_cap = arch_scale_cpu_capacity(cpu_dev->id);
        min_cap = div_u64((u64)max_cap * perf_caps->lowest_perf,
                          perf_caps->highest_perf);
        perf_step = div_u64((u64)CPPC_EM_CAP_STEP * perf_caps->highest_perf,
                            max_cap);
        min_step = min_cap / CPPC_EM_CAP_STEP;
        max_step = max_cap / CPPC_EM_CAP_STEP;

        perf_prev = cppc_khz_to_perf(perf_caps, *KHz);
        step = perf_prev / perf_step;

        if (step > max_step)
                return -EINVAL;

        if (min_step == max_step) {
                step = max_step;
                perf = perf_caps->highest_perf;
        } else if (step < min_step) {
                step = min_step;
                perf = perf_caps->lowest_perf;
        } else {
                step++;
                if (step == max_step)
                        perf = perf_caps->highest_perf;
                else
                        perf = step * perf_step;
        }

        *KHz = cppc_perf_to_khz(perf_caps, perf);
        perf_check = cppc_khz_to_perf(perf_caps, *KHz);
        step_check = perf_check / perf_step;

        /*
         * To avoid bad integer approximation, check that new frequency value
         * increased and that the new frequency will be converted to the
         * desired step value.
         */
        while ((*KHz == prev_freq) || (step_check != step)) {
                perf++;
                *KHz = cppc_perf_to_khz(perf_caps, perf);
                perf_check = cppc_khz_to_perf(perf_caps, *KHz);
                step_check = perf_check / perf_step;
        }

        /*
         * With an artificial EM, only the cost value is used. Still the power
         * is populated such as 0 < power < EM_MAX_POWER. This allows to add
         * more sense to the artificial performance states.
         */
        *power = compute_cost(cpu_dev->id, step);

        return 0;
}

static int cppc_get_cpu_cost(struct device *cpu_dev, unsigned long KHz,
                unsigned long *cost)
{
        unsigned long perf_step, perf_prev;
        struct cppc_perf_caps *perf_caps;
        struct cpufreq_policy *policy;
        struct cppc_cpudata *cpu_data;
        unsigned int max_cap;
        int step;

        policy = cpufreq_cpu_get_raw(cpu_dev->id);
        if (!policy)
                return -EINVAL;

        cpu_data = policy->driver_data;
        perf_caps = &cpu_data->perf_caps;
        max_cap = arch_scale_cpu_capacity(cpu_dev->id);

        perf_prev = cppc_khz_to_perf(perf_caps, KHz);
        perf_step = CPPC_EM_CAP_STEP * perf_caps->highest_perf / max_cap;
        step = perf_prev / perf_step;

        *cost = compute_cost(cpu_dev->id, step);

        return 0;
}

static void cppc_cpufreq_register_em(struct cpufreq_policy *policy)
{
        struct cppc_cpudata *cpu_data;
        struct em_data_callback em_cb =
                EM_ADV_DATA_CB(cppc_get_cpu_power, cppc_get_cpu_cost);

        cpu_data = policy->driver_data;
        em_dev_register_perf_domain(get_cpu_device(policy->cpu),
                        get_perf_level_count(policy), &em_cb,
                        cpu_data->shared_cpu_map, 0);
}

static void populate_efficiency_class(void)
{
        struct acpi_madt_generic_interrupt *gicc;
        DECLARE_BITMAP(used_classes, 256) = {};
        int class, cpu, index;

        for_each_possible_cpu(cpu) {
                gicc = acpi_cpu_get_madt_gicc(cpu);
                class = gicc->efficiency_class;
                bitmap_set(used_classes, class, 1);
        }

        if (bitmap_weight(used_classes, 256) <= 1) {
                pr_debug("Efficiency classes are all equal (=%d). "
                        "No EM registered", class);
                return;
        }

        /*
         * Squeeze efficiency class values on [0:#efficiency_class-1].
         * Values are per spec in [0:255].
         */
        index = 0;
        for_each_set_bit(class, used_classes, 256) {
                for_each_possible_cpu(cpu) {
                        gicc = acpi_cpu_get_madt_gicc(cpu);
                        if (gicc->efficiency_class == class)
                                per_cpu(efficiency_class, cpu) = index;
                }
                index++;
        }
        cppc_cpufreq_driver.register_em = cppc_cpufreq_register_em;
}

#else
static void populate_efficiency_class(void)
{
}
#endif

static struct cppc_cpudata *cppc_cpufreq_get_cpu_data(unsigned int cpu)
{
        struct cppc_cpudata *cpu_data;
        int ret;

        cpu_data = kzalloc_obj(struct cppc_cpudata);
        if (!cpu_data)
                goto out;

        if (!zalloc_cpumask_var(&cpu_data->shared_cpu_map, GFP_KERNEL))
                goto free_cpu;

        ret = acpi_get_psd_map(cpu, cpu_data);
        if (ret) {
                pr_debug("Err parsing CPU%d PSD data: ret:%d\n", cpu, ret);
                goto free_mask;
        }

        ret = cppc_get_perf_caps(cpu, &cpu_data->perf_caps);
        if (ret) {
                pr_debug("Err reading CPU%d perf caps: ret:%d\n", cpu, ret);
                goto free_mask;
        }

        return cpu_data;

free_mask:
        free_cpumask_var(cpu_data->shared_cpu_map);
free_cpu:
        kfree(cpu_data);
out:
        return NULL;
}

static void cppc_cpufreq_put_cpu_data(struct cpufreq_policy *policy)
{
        struct cppc_cpudata *cpu_data = policy->driver_data;

        free_cpumask_var(cpu_data->shared_cpu_map);
        kfree(cpu_data);
        policy->driver_data = NULL;
}

static int cppc_cpufreq_cpu_init(struct cpufreq_policy *policy)
{
        unsigned int cpu = policy->cpu;
        struct cppc_cpudata *cpu_data;
        struct cppc_perf_caps *caps;
        int ret;

        cpu_data = cppc_cpufreq_get_cpu_data(cpu);
        if (!cpu_data) {
                pr_err("Error in acquiring _CPC/_PSD data for CPU%d.\n", cpu);
                return -ENODEV;
        }
        caps = &cpu_data->perf_caps;
        policy->driver_data = cpu_data;

        /*
         * Set min to lowest nonlinear perf to avoid any efficiency penalty (see
         * Section 8.4.7.1.1.5 of ACPI 6.1 spec)
         */
        policy->min = cppc_perf_to_khz(caps, caps->lowest_nonlinear_perf);
        policy->max = cppc_perf_to_khz(caps, policy->boost_enabled ?
                                                caps->highest_perf : caps->nominal_perf);

        /*
         * Set cpuinfo.min_freq to Lowest to make the full range of performance
         * available if userspace wants to use any perf between lowest & lowest
         * nonlinear perf
         */
        policy->cpuinfo.min_freq = cppc_perf_to_khz(caps, caps->lowest_perf);
        policy->cpuinfo.max_freq = policy->max;

        policy->transition_delay_us = cppc_cpufreq_get_transition_delay_us(cpu);
        policy->shared_type = cpu_data->shared_type;

        switch (policy->shared_type) {
        case CPUFREQ_SHARED_TYPE_HW:
        case CPUFREQ_SHARED_TYPE_NONE:
                /* Nothing to be done - we'll have a policy for each CPU */
                break;
        case CPUFREQ_SHARED_TYPE_ANY:
                /*
                 * All CPUs in the domain will share a policy and all cpufreq
                 * operations will use a single cppc_cpudata structure stored
                 * in policy->driver_data.
                 */
                cpumask_copy(policy->cpus, cpu_data->shared_cpu_map);
                break;
        default:
                pr_debug("Unsupported CPU co-ord type: %d\n",
                         policy->shared_type);
                ret = -EFAULT;
                goto out;
        }

        policy->fast_switch_possible = cppc_allow_fast_switch();
        policy->dvfs_possible_from_any_cpu = true;

        /*
         * If 'highest_perf' is greater than 'nominal_perf', we assume CPU Boost
         * is supported.
         */
        if (caps->highest_perf > caps->nominal_perf)
                policy->boost_supported = true;

        /* Set policy->cur to max now. The governors will adjust later. */
        policy->cur = cppc_perf_to_khz(caps, caps->highest_perf);
        cpu_data->perf_ctrls.desired_perf =  caps->highest_perf;

        ret = cppc_set_perf(cpu, &cpu_data->perf_ctrls);
        if (ret) {
                pr_debug("Err setting perf value:%d on CPU:%d. ret:%d\n",
                         caps->highest_perf, cpu, ret);
                goto out;
        }

        cppc_cpufreq_cpu_fie_init(policy);
        return 0;

out:
        cppc_cpufreq_put_cpu_data(policy);
        return ret;
}

static void cppc_cpufreq_cpu_exit(struct cpufreq_policy *policy)
{
        struct cppc_cpudata *cpu_data = policy->driver_data;
        struct cppc_perf_caps *caps = &cpu_data->perf_caps;
        unsigned int cpu = policy->cpu;
        int ret;

        cppc_cpufreq_cpu_fie_exit(policy);

        cpu_data->perf_ctrls.desired_perf = caps->lowest_perf;

        ret = cppc_set_perf(cpu, &cpu_data->perf_ctrls);
        if (ret)
                pr_debug("Err setting perf value:%d on CPU:%d. ret:%d\n",
                         caps->lowest_perf, cpu, ret);

        cppc_cpufreq_put_cpu_data(policy);
}

static inline u64 get_delta(u64 t1, u64 t0)
{
        if (t1 > t0 || t0 > ~(u32)0)
                return t1 - t0;

        return (u32)t1 - (u32)t0;
}

static int cppc_perf_from_fbctrs(struct cppc_perf_fb_ctrs *fb_ctrs_t0,
                                 struct cppc_perf_fb_ctrs *fb_ctrs_t1)
{
        u64 delta_reference, delta_delivered;
        u64 reference_perf;

        reference_perf = fb_ctrs_t0->reference_perf;

        delta_reference = get_delta(fb_ctrs_t1->reference,
                                    fb_ctrs_t0->reference);
        delta_delivered = get_delta(fb_ctrs_t1->delivered,
                                    fb_ctrs_t0->delivered);

        /*
         * Avoid divide-by zero and unchanged feedback counters.
         * Leave it for callers to handle.
         */
        if (!delta_reference || !delta_delivered)
                return 0;

        return (reference_perf * delta_delivered) / delta_reference;
}

static int cppc_get_perf_ctrs_sample(int cpu,
                                     struct cppc_perf_fb_ctrs *fb_ctrs_t0,
                                     struct cppc_perf_fb_ctrs *fb_ctrs_t1)
{
        int ret;

        ret = cppc_get_perf_ctrs(cpu, fb_ctrs_t0);
        if (ret)
                return ret;

        udelay(2); /* 2usec delay between sampling */

        return cppc_get_perf_ctrs(cpu, fb_ctrs_t1);
}

static unsigned int cppc_cpufreq_get_rate(unsigned int cpu)
{
        struct cpufreq_policy *policy __free(put_cpufreq_policy) = cpufreq_cpu_get(cpu);
        struct cppc_perf_fb_ctrs fb_ctrs_t0 = {0}, fb_ctrs_t1 = {0};
        struct cppc_cpudata *cpu_data;
        u64 delivered_perf;
        int ret;

        if (!policy)
                return 0;

        cpu_data = policy->driver_data;

        ret = cppc_get_perf_ctrs_sample(cpu, &fb_ctrs_t0, &fb_ctrs_t1);
        if (ret) {
                if (ret == -EFAULT)
                        /* Any of the associated CPPC regs is 0. */
                        goto out_invalid_counters;
                else
                        return 0;
        }

        delivered_perf = cppc_perf_from_fbctrs(&fb_ctrs_t0, &fb_ctrs_t1);
        if (!delivered_perf)
                goto out_invalid_counters;

        return cppc_perf_to_khz(&cpu_data->perf_caps, delivered_perf);

out_invalid_counters:
        /*
         * Feedback counters could be unchanged or 0 when a cpu enters a
         * low-power idle state, e.g. clock-gated or power-gated.
         * Use desired perf for reflecting frequency.  Get the latest register
         * value first as some platforms may update the actual delivered perf
         * there; if failed, resort to the cached desired perf.
         */
        if (cppc_get_desired_perf(cpu, &delivered_perf))
                delivered_perf = cpu_data->perf_ctrls.desired_perf;

        return cppc_perf_to_khz(&cpu_data->perf_caps, delivered_perf);
}

static int cppc_cpufreq_set_boost(struct cpufreq_policy *policy, int state)
{
        struct cppc_cpudata *cpu_data = policy->driver_data;
        struct cppc_perf_caps *caps = &cpu_data->perf_caps;
        int ret;

        if (state)
                policy->max = cppc_perf_to_khz(caps, caps->highest_perf);
        else
                policy->max = cppc_perf_to_khz(caps, caps->nominal_perf);
        policy->cpuinfo.max_freq = policy->max;

        ret = freq_qos_update_request(policy->max_freq_req, policy->max);
        if (ret < 0)
                return ret;

        return 0;
}

static ssize_t show_freqdomain_cpus(struct cpufreq_policy *policy, char *buf)
{
        struct cppc_cpudata *cpu_data = policy->driver_data;

        return cpufreq_show_cpus(cpu_data->shared_cpu_map, buf);
}

static ssize_t show_auto_select(struct cpufreq_policy *policy, char *buf)
{
        bool val;
        int ret;

        ret = cppc_get_auto_sel(policy->cpu, &val);

        /* show "<unsupported>" when this register is not supported by cpc */
        if (ret == -EOPNOTSUPP)
                return sysfs_emit(buf, "<unsupported>\n");

        if (ret)
                return ret;

        return sysfs_emit(buf, "%d\n", val);
}

static ssize_t store_auto_select(struct cpufreq_policy *policy,
                                 const char *buf, size_t count)
{
        bool val;
        int ret;

        ret = kstrtobool(buf, &val);
        if (ret)
                return ret;

        ret = cppc_set_auto_sel(policy->cpu, val);
        if (ret)
                return ret;

        return count;
}

static ssize_t cppc_cpufreq_sysfs_show_u64(unsigned int cpu,
                                           int (*get_func)(int, u64 *),
                                           char *buf)
{
        u64 val;
        int ret = get_func((int)cpu, &val);

        if (ret == -EOPNOTSUPP)
                return sysfs_emit(buf, "<unsupported>\n");

        if (ret)
                return ret;

        return sysfs_emit(buf, "%llu\n", val);
}

static ssize_t cppc_cpufreq_sysfs_store_u64(unsigned int cpu,
                                            int (*set_func)(int, u64),
                                            const char *buf, size_t count)
{
        u64 val;
        int ret;

        ret = kstrtou64(buf, 0, &val);
        if (ret)
                return ret;

        ret = set_func((int)cpu, val);

        return ret ? ret : count;
}

#define CPPC_CPUFREQ_ATTR_RW_U64(_name, _get_func, _set_func)           \
static ssize_t show_##_name(struct cpufreq_policy *policy, char *buf)   \
{                                                                       \
        return cppc_cpufreq_sysfs_show_u64(policy->cpu, _get_func, buf);\
}                                                                       \
static ssize_t store_##_name(struct cpufreq_policy *policy,             \
                             const char *buf, size_t count)             \
{                                                                       \
        return cppc_cpufreq_sysfs_store_u64(policy->cpu, _set_func,     \
                                            buf, count);                \
}

CPPC_CPUFREQ_ATTR_RW_U64(auto_act_window, cppc_get_auto_act_window,
                         cppc_set_auto_act_window)

CPPC_CPUFREQ_ATTR_RW_U64(energy_performance_preference_val,
                         cppc_get_epp_perf, cppc_set_epp)

cpufreq_freq_attr_ro(freqdomain_cpus);
cpufreq_freq_attr_rw(auto_select);
cpufreq_freq_attr_rw(auto_act_window);
cpufreq_freq_attr_rw(energy_performance_preference_val);

static struct freq_attr *cppc_cpufreq_attr[] = {
        &freqdomain_cpus,
        &auto_select,
        &auto_act_window,
        &energy_performance_preference_val,
        NULL,
};

static struct cpufreq_driver cppc_cpufreq_driver = {
        .flags = CPUFREQ_CONST_LOOPS | CPUFREQ_NEED_UPDATE_LIMITS,
        .verify = cppc_verify_policy,
        .target = cppc_cpufreq_set_target,
        .get = cppc_cpufreq_get_rate,
        .fast_switch = cppc_cpufreq_fast_switch,
        .init = cppc_cpufreq_cpu_init,
        .exit = cppc_cpufreq_cpu_exit,
        .set_boost = cppc_cpufreq_set_boost,
        .attr = cppc_cpufreq_attr,
        .name = "cppc_cpufreq",
};

static int __init cppc_cpufreq_init(void)
{
        int ret;

        if (!acpi_cpc_valid())
                return -ENODEV;

        cppc_freq_invariance_init();
        populate_efficiency_class();

        ret = cpufreq_register_driver(&cppc_cpufreq_driver);
        if (ret)
                cppc_freq_invariance_exit();

        return ret;
}

static void __exit cppc_cpufreq_exit(void)
{
        cpufreq_unregister_driver(&cppc_cpufreq_driver);
        cppc_freq_invariance_exit();
}

module_exit(cppc_cpufreq_exit);
MODULE_AUTHOR("Ashwin Chaugule");
MODULE_DESCRIPTION("CPUFreq driver based on the ACPI CPPC v5.0+ spec");
MODULE_LICENSE("GPL");

late_initcall(cppc_cpufreq_init);

static const struct acpi_device_id cppc_acpi_ids[] __used = {
        {ACPI_PROCESSOR_DEVICE_HID, },
        {}
};

MODULE_DEVICE_TABLE(acpi, cppc_acpi_ids);