// 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/kernel.h>
#include <linux/module.h>
#include <linux/delay.h>
#include <linux/cpu.h>
#include <linux/cpufreq.h>
#include <linux/dmi.h>
#include <linux/time.h>
#include <linux/vmalloc.h>

#include <asm/unaligned.h>

#include <acpi/cppc_acpi.h>

/* Minimum struct length needed for the DMI processor entry we want */
#define DMI_ENTRY_PROCESSOR_MIN_LENGTH  48

/* Offset in the DMI processor structure for the max frequency */
#define DMI_PROCESSOR_MAX_SPEED         0x14

/*
 * This list contains information parsed from per CPU ACPI _CPC and _PSD
 * structures: e.g. the highest and lowest supported performance, capabilities,
 * desired performance, level requested etc. Depending on the share_type, not
 * all CPUs will have an entry in the list.
 */
static LIST_HEAD(cpu_data_list);

static bool boost_supported;

struct cppc_workaround_oem_info {
        char oem_id[ACPI_OEM_ID_SIZE + 1];
        char oem_table_id[ACPI_OEM_TABLE_ID_SIZE + 1];
        u32 oem_revision;
};

static struct cppc_workaround_oem_info wa_info[] = {
        {
                .oem_id         = "HISI  ",
                .oem_table_id   = "HIP07   ",
                .oem_revision   = 0,
        }, {
                .oem_id         = "HISI  ",
                .oem_table_id   = "HIP08   ",
                .oem_revision   = 0,
        }
};

/* Callback function used to retrieve the max frequency from DMI */
static void cppc_find_dmi_mhz(const struct dmi_header *dm, void *private)
{
        const u8 *dmi_data = (const u8 *)dm;
        u16 *mhz = (u16 *)private;

        if (dm->type == DMI_ENTRY_PROCESSOR &&
            dm->length >= DMI_ENTRY_PROCESSOR_MIN_LENGTH) {
                u16 val = (u16)get_unaligned((const u16 *)
                                (dmi_data + DMI_PROCESSOR_MAX_SPEED));
                *mhz = val > *mhz ? val : *mhz;
        }
}

/* Look up the max frequency in DMI */
static u64 cppc_get_dmi_max_khz(void)
{
        u16 mhz = 0;

        dmi_walk(cppc_find_dmi_mhz, &mhz);

        /*
         * Real stupid fallback value, just in case there is no
         * actual value set.
         */
        mhz = mhz ? mhz : 1;

        return (1000 * mhz);
}

/*
 * If CPPC lowest_freq and nominal_freq registers are exposed then we can
 * use them to convert perf to freq and vice versa
 *
 * If the perf/freq point lies between Nominal and Lowest, we can treat
 * (Low perf, Low freq) and (Nom Perf, Nom freq) as 2D co-ordinates of a line
 * and extrapolate the rest
 * For perf/freq > Nominal, we use the ratio perf:freq at Nominal for conversion
 */
static unsigned int cppc_cpufreq_perf_to_khz(struct cppc_cpudata *cpu_data,
                                             unsigned int perf)
{
        struct cppc_perf_caps *caps = &cpu_data->perf_caps;
        static u64 max_khz;
        u64 mul, div;

        if (caps->lowest_freq && caps->nominal_freq) {
                if (perf >= caps->nominal_perf) {
                        mul = caps->nominal_freq;
                        div = caps->nominal_perf;
                } else {
                        mul = caps->nominal_freq - caps->lowest_freq;
                        div = caps->nominal_perf - caps->lowest_perf;
                }
        } else {
                if (!max_khz)
                        max_khz = cppc_get_dmi_max_khz();
                mul = max_khz;
                div = caps->highest_perf;
        }
        return (u64)perf * mul / div;
}

static unsigned int cppc_cpufreq_khz_to_perf(struct cppc_cpudata *cpu_data,
                                             unsigned int freq)
{
        struct cppc_perf_caps *caps = &cpu_data->perf_caps;
        static u64 max_khz;
        u64  mul, div;

        if (caps->lowest_freq && caps->nominal_freq) {
                if (freq >= caps->nominal_freq) {
                        mul = caps->nominal_perf;
                        div = caps->nominal_freq;
                } else {
                        mul = caps->lowest_perf;
                        div = caps->lowest_freq;
                }
        } else {
                if (!max_khz)
                        max_khz = cppc_get_dmi_max_khz();
                mul = caps->highest_perf;
                div = max_khz;
        }

        return (u64)freq * mul / div;
}

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;
        u32 desired_perf;
        int ret = 0;

        desired_perf = cppc_cpufreq_khz_to_perf(cpu_data, target_freq);
        /* Return if it is exactly the same perf */
        if (desired_perf == cpu_data->perf_ctrls.desired_perf)
                return ret;

        cpu_data->perf_ctrls.desired_perf = desired_perf;
        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 int cppc_verify_policy(struct cpufreq_policy_data *policy)
{
        cpufreq_verify_within_cpu_limits(policy);
        return 0;
}

static void cppc_cpufreq_stop_cpu(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;

        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);

        /* Remove CPU node from list and free driver data for policy */
        free_cpumask_var(cpu_data->shared_cpu_map);
        list_del(&cpu_data->node);
        kfree(policy->driver_data);
        policy->driver_data = NULL;
}

/*
 * 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();
        unsigned int delay_us = 0;

        switch (implementor) {
        case ARM_CPU_IMP_QCOM:
                switch (part_num) {
                case QCOM_CPU_PART_FALKOR_V1:
                case QCOM_CPU_PART_FALKOR:
                        delay_us = 10000;
                        break;
                default:
                        delay_us = cppc_get_transition_latency(cpu) / NSEC_PER_USEC;
                        break;
                }
                break;
        default:
                delay_us = cppc_get_transition_latency(cpu) / NSEC_PER_USEC;
                break;
        }

        return delay_us;
}

#else

static unsigned int cppc_cpufreq_get_transition_delay_us(unsigned int cpu)
{
        return cppc_get_transition_latency(cpu) / NSEC_PER_USEC;
}
#endif


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

        cpu_data = kzalloc(sizeof(struct cppc_cpudata), GFP_KERNEL);
        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;
        }

        /* Convert the lowest and nominal freq from MHz to KHz */
        cpu_data->perf_caps.lowest_freq *= 1000;
        cpu_data->perf_caps.nominal_freq *= 1000;

        list_add(&cpu_data->node, &cpu_data_list);

        return cpu_data;

free_mask:
        free_cpumask_var(cpu_data->shared_cpu_map);
free_cpu:
        kfree(cpu_data);
out:
        return 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_cpufreq_perf_to_khz(cpu_data,
                                               caps->lowest_nonlinear_perf);
        policy->max = cppc_cpufreq_perf_to_khz(cpu_data,
                                               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_cpufreq_perf_to_khz(cpu_data,
                                                            caps->lowest_perf);
        policy->cpuinfo.max_freq = cppc_cpufreq_perf_to_khz(cpu_data,
                                                            caps->nominal_perf);

        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);
                return -EFAULT;
        }

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

        /* Set policy->cur to max now. The governors will adjust later. */
        policy->cur = cppc_cpufreq_perf_to_khz(cpu_data, 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);

        return ret;
}

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_get_rate_from_fbctrs(struct cppc_cpudata *cpu_data,
                                     struct cppc_perf_fb_ctrs fb_ctrs_t0,
                                     struct cppc_perf_fb_ctrs fb_ctrs_t1)
{
        u64 delta_reference, delta_delivered;
        u64 reference_perf, delivered_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);

        /* Check to avoid divide-by zero */
        if (delta_reference || delta_delivered)
                delivered_perf = (reference_perf * delta_delivered) /
                                        delta_reference;
        else
                delivered_perf = cpu_data->perf_ctrls.desired_perf;

        return cppc_cpufreq_perf_to_khz(cpu_data, delivered_perf);
}

static unsigned int cppc_cpufreq_get_rate(unsigned int cpu)
{
        struct cppc_perf_fb_ctrs fb_ctrs_t0 = {0}, fb_ctrs_t1 = {0};
        struct cpufreq_policy *policy = cpufreq_cpu_get(cpu);
        struct cppc_cpudata *cpu_data = policy->driver_data;
        int ret;

        cpufreq_cpu_put(policy);

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

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

        ret = cppc_get_perf_ctrs(cpu, &fb_ctrs_t1);
        if (ret)
                return ret;

        return cppc_get_rate_from_fbctrs(cpu_data, fb_ctrs_t0, fb_ctrs_t1);
}

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 (!boost_supported) {
                pr_err("BOOST not supported by CPU or firmware\n");
                return -EINVAL;
        }

        if (state)
                policy->max = cppc_cpufreq_perf_to_khz(cpu_data,
                                                       caps->highest_perf);
        else
                policy->max = cppc_cpufreq_perf_to_khz(cpu_data,
                                                       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);
}
cpufreq_freq_attr_ro(freqdomain_cpus);

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

static struct cpufreq_driver cppc_cpufreq_driver = {
        .flags = CPUFREQ_CONST_LOOPS,
        .verify = cppc_verify_policy,
        .target = cppc_cpufreq_set_target,
        .get = cppc_cpufreq_get_rate,
        .init = cppc_cpufreq_cpu_init,
        .stop_cpu = cppc_cpufreq_stop_cpu,
        .set_boost = cppc_cpufreq_set_boost,
        .attr = cppc_cpufreq_attr,
        .name = "cppc_cpufreq",
};

/*
 * HISI platform does not support delivered performance counter and
 * reference performance counter. It can calculate the performance using the
 * platform specific mechanism. We reuse the desired performance register to
 * store the real performance calculated by the platform.
 */
static unsigned int hisi_cppc_cpufreq_get_rate(unsigned int cpu)
{
        struct cpufreq_policy *policy = cpufreq_cpu_get(cpu);
        struct cppc_cpudata *cpu_data = policy->driver_data;
        u64 desired_perf;
        int ret;

        cpufreq_cpu_put(policy);

        ret = cppc_get_desired_perf(cpu, &desired_perf);
        if (ret < 0)
                return -EIO;

        return cppc_cpufreq_perf_to_khz(cpu_data, desired_perf);
}

static void cppc_check_hisi_workaround(void)
{
        struct acpi_table_header *tbl;
        acpi_status status = AE_OK;
        int i;

        status = acpi_get_table(ACPI_SIG_PCCT, 0, &tbl);
        if (ACPI_FAILURE(status) || !tbl)
                return;

        for (i = 0; i < ARRAY_SIZE(wa_info); i++) {
                if (!memcmp(wa_info[i].oem_id, tbl->oem_id, ACPI_OEM_ID_SIZE) &&
                    !memcmp(wa_info[i].oem_table_id, tbl->oem_table_id, ACPI_OEM_TABLE_ID_SIZE) &&
                    wa_info[i].oem_revision == tbl->oem_revision) {
                        /* Overwrite the get() callback */
                        cppc_cpufreq_driver.get = hisi_cppc_cpufreq_get_rate;
                        break;
                }
        }

        acpi_put_table(tbl);
}

static int __init cppc_cpufreq_init(void)
{
        if ((acpi_disabled) || !acpi_cpc_valid())
                return -ENODEV;

        INIT_LIST_HEAD(&cpu_data_list);

        cppc_check_hisi_workaround();

        return cpufreq_register_driver(&cppc_cpufreq_driver);
}

static inline void free_cpu_data(void)
{
        struct cppc_cpudata *iter, *tmp;

        list_for_each_entry_safe(iter, tmp, &cpu_data_list, node) {
                free_cpumask_var(iter->shared_cpu_map);
                list_del(&iter->node);
                kfree(iter);
        }

}

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

        free_cpu_data();
}

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);