// SPDX-License-Identifier: GPL-2.0-only
/*
 *  AMD K7 Powernow driver.
 *  (C) 2003 Dave Jones on behalf of SuSE Labs.
 *
 *  Based upon datasheets & sample CPUs kindly provided by AMD.
 *
 * Errata 5:
 *  CPU may fail to execute a FID/VID change in presence of interrupt.
 *  - We cli/sti on stepping A0 CPUs around the FID/VID transition.
 * Errata 15:
 *  CPU with half frequency multipliers may hang upon wakeup from disconnect.
 *  - We disable half multipliers if ACPI is used on A0 stepping CPUs.
 */

#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/moduleparam.h>
#include <linux/init.h>
#include <linux/cpufreq.h>
#include <linux/slab.h>
#include <linux/string.h>
#include <linux/dmi.h>
#include <linux/timex.h>
#include <linux/io.h>

#include <asm/timer.h>          /* Needed for recalibrate_cpu_khz() */
#include <asm/msr.h>
#include <asm/cpu_device_id.h>

#ifdef CONFIG_X86_POWERNOW_K7_ACPI
#include <linux/acpi.h>
#include <acpi/processor.h>
#endif

#include "powernow-k7.h"

struct psb_s {
        u8 signature[10];
        u8 tableversion;
        u8 flags;
        u16 settlingtime;
        u8 reserved1;
        u8 numpst;
};

struct pst_s {
        u32 cpuid;
        u8 fsbspeed;
        u8 maxfid;
        u8 startvid;
        u8 numpstates;
};

#ifdef CONFIG_X86_POWERNOW_K7_ACPI
union powernow_acpi_control_t {
        struct {
                unsigned long fid:5,
                        vid:5,
                        sgtc:20,
                        res1:2;
        } bits;
        unsigned long val;
};
#endif

/* divide by 1000 to get VCore voltage in V. */
static const int mobile_vid_table[32] = {
    2000, 1950, 1900, 1850, 1800, 1750, 1700, 1650,
    1600, 1550, 1500, 1450, 1400, 1350, 1300, 0,
    1275, 1250, 1225, 1200, 1175, 1150, 1125, 1100,
    1075, 1050, 1025, 1000, 975, 950, 925, 0,
};

/* divide by 10 to get FID. */
static const int fid_codes[32] = {
    110, 115, 120, 125, 50, 55, 60, 65,
    70, 75, 80, 85, 90, 95, 100, 105,
    30, 190, 40, 200, 130, 135, 140, 210,
    150, 225, 160, 165, 170, 180, -1, -1,
};

/* This parameter is used in order to force ACPI instead of legacy method for
 * configuration purpose.
 */

static int acpi_force;

static struct cpufreq_frequency_table *powernow_table;

static unsigned int can_scale_bus;
static unsigned int can_scale_vid;
static unsigned int minimum_speed = -1;
static unsigned int maximum_speed;
static unsigned int number_scales;
static unsigned int fsb;
static unsigned int latency;
static char have_a0;

static int check_fsb(unsigned int fsbspeed)
{
        int delta;
        unsigned int f = fsb / 1000;

        delta = (fsbspeed > f) ? fsbspeed - f : f - fsbspeed;
        return delta < 5;
}

static const struct x86_cpu_id powernow_k7_cpuids[] = {
        X86_MATCH_VENDOR_FAM(AMD, 6, NULL),
        {}
};
MODULE_DEVICE_TABLE(x86cpu, powernow_k7_cpuids);

static int check_powernow(void)
{
        struct cpuinfo_x86 *c = &cpu_data(0);
        unsigned int maxei, eax, ebx, ecx, edx;

        if (!x86_match_cpu(powernow_k7_cpuids))
                return 0;

        /* Get maximum capabilities */
        maxei = cpuid_eax(0x80000000);
        if (maxei < 0x80000007) {       /* Any powernow info ? */
#ifdef MODULE
                pr_info("No powernow capabilities detected\n");
#endif
                return 0;
        }

        if ((c->x86_model == 6) && (c->x86_stepping == 0)) {
                pr_info("K7 660[A0] core detected, enabling errata workarounds\n");
                have_a0 = 1;
        }

        cpuid(0x80000007, &eax, &ebx, &ecx, &edx);

        /* Check we can actually do something before we say anything.*/
        if (!(edx & (1 << 1 | 1 << 2)))
                return 0;

        pr_info("PowerNOW! Technology present. Can scale: ");

        if (edx & 1 << 1) {
                pr_cont("frequency");
                can_scale_bus = 1;
        }

        if ((edx & (1 << 1 | 1 << 2)) == 0x6)
                pr_cont(" and ");

        if (edx & 1 << 2) {
                pr_cont("voltage");
                can_scale_vid = 1;
        }

        pr_cont("\n");
        return 1;
}

#ifdef CONFIG_X86_POWERNOW_K7_ACPI
static void invalidate_entry(unsigned int entry)
{
        powernow_table[entry].frequency = CPUFREQ_ENTRY_INVALID;
}
#endif

static int get_ranges(unsigned char *pst)
{
        unsigned int j;
        unsigned int speed;
        u8 fid, vid;

        powernow_table = kzalloc((sizeof(*powernow_table) *
                                (number_scales + 1)), GFP_KERNEL);
        if (!powernow_table)
                return -ENOMEM;

        for (j = 0 ; j < number_scales; j++) {
                fid = *pst++;

                powernow_table[j].frequency = (fsb * fid_codes[fid]) / 10;
                powernow_table[j].driver_data = fid; /* lower 8 bits */

                speed = powernow_table[j].frequency;

                if ((fid_codes[fid] % 10) == 5) {
#ifdef CONFIG_X86_POWERNOW_K7_ACPI
                        if (have_a0 == 1)
                                invalidate_entry(j);
#endif
                }

                if (speed < minimum_speed)
                        minimum_speed = speed;
                if (speed > maximum_speed)
                        maximum_speed = speed;

                vid = *pst++;
                powernow_table[j].driver_data |= (vid << 8); /* upper 8 bits */

                pr_debug("   FID: 0x%x (%d.%dx [%dMHz])  "
                         "VID: 0x%x (%d.%03dV)\n", fid, fid_codes[fid] / 10,
                         fid_codes[fid] % 10, speed/1000, vid,
                         mobile_vid_table[vid]/1000,
                         mobile_vid_table[vid]%1000);
        }
        powernow_table[number_scales].frequency = CPUFREQ_TABLE_END;
        powernow_table[number_scales].driver_data = 0;

        return 0;
}


static void change_FID(int fid)
{
        union msr_fidvidctl fidvidctl;

        rdmsrq(MSR_K7_FID_VID_CTL, fidvidctl.val);
        if (fidvidctl.bits.FID != fid) {
                fidvidctl.bits.SGTC = latency;
                fidvidctl.bits.FID = fid;
                fidvidctl.bits.VIDC = 0;
                fidvidctl.bits.FIDC = 1;
                wrmsrq(MSR_K7_FID_VID_CTL, fidvidctl.val);
        }
}


static void change_VID(int vid)
{
        union msr_fidvidctl fidvidctl;

        rdmsrq(MSR_K7_FID_VID_CTL, fidvidctl.val);
        if (fidvidctl.bits.VID != vid) {
                fidvidctl.bits.SGTC = latency;
                fidvidctl.bits.VID = vid;
                fidvidctl.bits.FIDC = 0;
                fidvidctl.bits.VIDC = 1;
                wrmsrq(MSR_K7_FID_VID_CTL, fidvidctl.val);
        }
}


static int powernow_target(struct cpufreq_policy *policy, unsigned int index)
{
        u8 fid, vid;
        struct cpufreq_freqs freqs;
        union msr_fidvidstatus fidvidstatus;
        int cfid;

        /* fid are the lower 8 bits of the index we stored into
         * the cpufreq frequency table in powernow_decode_bios,
         * vid are the upper 8 bits.
         */

        fid = powernow_table[index].driver_data & 0xFF;
        vid = (powernow_table[index].driver_data & 0xFF00) >> 8;

        rdmsrq(MSR_K7_FID_VID_STATUS, fidvidstatus.val);
        cfid = fidvidstatus.bits.CFID;
        freqs.old = fsb * fid_codes[cfid] / 10;

        freqs.new = powernow_table[index].frequency;

        /* Now do the magic poking into the MSRs.  */

        if (have_a0 == 1)       /* A0 errata 5 */
                local_irq_disable();

        if (freqs.old > freqs.new) {
                /* Going down, so change FID first */
                change_FID(fid);
                change_VID(vid);
        } else {
                /* Going up, so change VID first */
                change_VID(vid);
                change_FID(fid);
        }


        if (have_a0 == 1)
                local_irq_enable();

        return 0;
}


#ifdef CONFIG_X86_POWERNOW_K7_ACPI

static struct acpi_processor_performance *acpi_processor_perf;

static int powernow_acpi_init(void)
{
        int i;
        int retval = 0;
        union powernow_acpi_control_t pc;

        if (acpi_processor_perf != NULL && powernow_table != NULL) {
                retval = -EINVAL;
                goto err0;
        }

        acpi_processor_perf = kzalloc_obj(*acpi_processor_perf);
        if (!acpi_processor_perf) {
                retval = -ENOMEM;
                goto err0;
        }

        if (!zalloc_cpumask_var(&acpi_processor_perf->shared_cpu_map,
                                                                GFP_KERNEL)) {
                retval = -ENOMEM;
                goto err05;
        }

        if (acpi_processor_register_performance(acpi_processor_perf, 0)) {
                retval = -EIO;
                goto err1;
        }

        if (acpi_processor_perf->control_register.space_id !=
                        ACPI_ADR_SPACE_FIXED_HARDWARE) {
                retval = -ENODEV;
                goto err2;
        }

        if (acpi_processor_perf->status_register.space_id !=
                        ACPI_ADR_SPACE_FIXED_HARDWARE) {
                retval = -ENODEV;
                goto err2;
        }

        number_scales = acpi_processor_perf->state_count;

        if (number_scales < 2) {
                retval = -ENODEV;
                goto err2;
        }

        powernow_table = kzalloc((sizeof(*powernow_table) *
                                (number_scales + 1)), GFP_KERNEL);
        if (!powernow_table) {
                retval = -ENOMEM;
                goto err2;
        }

        pc.val = (unsigned long) acpi_processor_perf->states[0].control;
        for (i = 0; i < number_scales; i++) {
                u8 fid, vid;
                struct acpi_processor_px *state =
                        &acpi_processor_perf->states[i];
                unsigned int speed, speed_mhz;

                pc.val = (unsigned long) state->control;
                pr_debug("acpi:  P%d: %d MHz %d mW %d uS control %08x SGTC %d\n",
                         i,
                         (u32) state->core_frequency,
                         (u32) state->power,
                         (u32) state->transition_latency,
                         (u32) state->control,
                         pc.bits.sgtc);

                vid = pc.bits.vid;
                fid = pc.bits.fid;

                powernow_table[i].frequency = fsb * fid_codes[fid] / 10;
                powernow_table[i].driver_data = fid; /* lower 8 bits */
                powernow_table[i].driver_data |= (vid << 8); /* upper 8 bits */

                speed = powernow_table[i].frequency;
                speed_mhz = speed / 1000;

                /* processor_perflib will multiply the MHz value by 1000 to
                 * get a KHz value (e.g. 1266000). However, powernow-k7 works
                 * with true KHz values (e.g. 1266768). To ensure that all
                 * powernow frequencies are available, we must ensure that
                 * ACPI doesn't restrict them, so we round up the MHz value
                 * to ensure that perflib's computed KHz value is greater than
                 * or equal to powernow's KHz value.
                 */
                if (speed % 1000 > 0)
                        speed_mhz++;

                if ((fid_codes[fid] % 10) == 5) {
                        if (have_a0 == 1)
                                invalidate_entry(i);
                }

                pr_debug("   FID: 0x%x (%d.%dx [%dMHz])  "
                         "VID: 0x%x (%d.%03dV)\n", fid, fid_codes[fid] / 10,
                         fid_codes[fid] % 10, speed_mhz, vid,
                         mobile_vid_table[vid]/1000,
                         mobile_vid_table[vid]%1000);

                if (state->core_frequency != speed_mhz) {
                        state->core_frequency = speed_mhz;
                        pr_debug("   Corrected ACPI frequency to %d\n",
                                speed_mhz);
                }

                if (latency < pc.bits.sgtc)
                        latency = pc.bits.sgtc;

                if (speed < minimum_speed)
                        minimum_speed = speed;
                if (speed > maximum_speed)
                        maximum_speed = speed;
        }

        powernow_table[i].frequency = CPUFREQ_TABLE_END;
        powernow_table[i].driver_data = 0;

        /* notify BIOS that we exist */
        acpi_processor_notify_smm(THIS_MODULE);

        return 0;

err2:
        acpi_processor_unregister_performance(0);
err1:
        free_cpumask_var(acpi_processor_perf->shared_cpu_map);
err05:
        kfree(acpi_processor_perf);
err0:
        pr_warn("ACPI perflib can not be used on this platform\n");
        acpi_processor_perf = NULL;
        return retval;
}
#else
static int powernow_acpi_init(void)
{
        pr_info("no support for ACPI processor found - please recompile your kernel with ACPI processor\n");
        return -EINVAL;
}
#endif

static void print_pst_entry(struct pst_s *pst, unsigned int j)
{
        pr_debug("PST:%d (@%p)\n", j, pst);
        pr_debug(" cpuid: 0x%x  fsb: %d  maxFID: 0x%x  startvid: 0x%x\n",
                pst->cpuid, pst->fsbspeed, pst->maxfid, pst->startvid);
}

static int powernow_decode_bios(int maxfid, int startvid)
{
        struct psb_s *psb;
        struct pst_s *pst;
        unsigned int i, j;
        unsigned char *p;
        unsigned int etuple;
        unsigned int ret;

        etuple = cpuid_eax(0x80000001);

        for (i = 0xC0000; i < 0xffff0 ; i += 16) {

                p = phys_to_virt(i);

                if (memcmp(p, "AMDK7PNOW!",  10) == 0) {
                        pr_debug("Found PSB header at %p\n", p);
                        psb = (struct psb_s *) p;
                        pr_debug("Table version: 0x%x\n", psb->tableversion);
                        if (psb->tableversion != 0x12) {
                                pr_info("Sorry, only v1.2 tables supported right now\n");
                                return -ENODEV;
                        }

                        pr_debug("Flags: 0x%x\n", psb->flags);
                        if ((psb->flags & 1) == 0)
                                pr_debug("Mobile voltage regulator\n");
                        else
                                pr_debug("Desktop voltage regulator\n");

                        latency = psb->settlingtime;
                        if (latency < 100) {
                                pr_info("BIOS set settling time to %d microseconds. Should be at least 100. Correcting.\n",
                                        latency);
                                latency = 100;
                        }
                        pr_debug("Settling Time: %d microseconds.\n",
                                        psb->settlingtime);
                        pr_debug("Has %d PST tables. (Only dumping ones "
                                        "relevant to this CPU).\n",
                                        psb->numpst);

                        p += sizeof(*psb);

                        pst = (struct pst_s *) p;

                        for (j = 0; j < psb->numpst; j++) {
                                pst = (struct pst_s *) p;
                                number_scales = pst->numpstates;

                                if ((etuple == pst->cpuid) &&
                                    check_fsb(pst->fsbspeed) &&
                                    (maxfid == pst->maxfid) &&
                                    (startvid == pst->startvid)) {
                                        print_pst_entry(pst, j);
                                        p = (char *)pst + sizeof(*pst);
                                        ret = get_ranges(p);
                                        return ret;
                                } else {
                                        unsigned int k;
                                        p = (char *)pst + sizeof(*pst);
                                        for (k = 0; k < number_scales; k++)
                                                p += 2;
                                }
                        }
                        pr_info("No PST tables match this cpuid (0x%x)\n",
                                etuple);
                        pr_info("This is indicative of a broken BIOS\n");

                        return -EINVAL;
                }
                p++;
        }

        return -ENODEV;
}


/*
 * We use the fact that the bus frequency is somehow
 * a multiple of 100000/3 khz, then we compute sgtc according
 * to this multiple.
 * That way, we match more how AMD thinks all of that work.
 * We will then get the same kind of behaviour already tested under
 * the "well-known" other OS.
 */
static int fixup_sgtc(void)
{
        unsigned int sgtc;
        unsigned int m;

        m = fsb / 3333;
        if ((m % 10) >= 5)
                m += 5;

        m /= 10;

        sgtc = 100 * m * latency;
        sgtc = sgtc / 3;
        if (sgtc > 0xfffff) {
                pr_warn("SGTC too large %d\n", sgtc);
                sgtc = 0xfffff;
        }
        return sgtc;
}

static unsigned int powernow_get(unsigned int cpu)
{
        union msr_fidvidstatus fidvidstatus;
        unsigned int cfid;

        if (cpu)
                return 0;
        rdmsrq(MSR_K7_FID_VID_STATUS, fidvidstatus.val);
        cfid = fidvidstatus.bits.CFID;

        return fsb * fid_codes[cfid] / 10;
}


static int acer_cpufreq_pst(const struct dmi_system_id *d)
{
        pr_warn("%s laptop with broken PST tables in BIOS detected\n",
                d->ident);
        pr_warn("You need to downgrade to 3A21 (09/09/2002), or try a newer BIOS than 3A71 (01/20/2003)\n");
        pr_warn("cpufreq scaling has been disabled as a result of this\n");
        return 0;
}

/*
 * Some Athlon laptops have really fucked PST tables.
 * A BIOS update is all that can save them.
 * Mention this, and disable cpufreq.
 */
static const struct dmi_system_id powernow_dmi_table[] = {
        {
                .callback = acer_cpufreq_pst,
                .ident = "Acer Aspire",
                .matches = {
                        DMI_MATCH(DMI_SYS_VENDOR, "Insyde Software"),
                        DMI_MATCH(DMI_BIOS_VERSION, "3A71"),
                },
        },
        { }
};

static int powernow_cpu_init(struct cpufreq_policy *policy)
{
        union msr_fidvidstatus fidvidstatus;
        int result;

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

        rdmsrq(MSR_K7_FID_VID_STATUS, fidvidstatus.val);

        recalibrate_cpu_khz();

        fsb = (10 * cpu_khz) / fid_codes[fidvidstatus.bits.CFID];
        if (!fsb) {
                pr_warn("can not determine bus frequency\n");
                return -EINVAL;
        }
        pr_debug("FSB: %3dMHz\n", fsb/1000);

        if (dmi_check_system(powernow_dmi_table) || acpi_force) {
                pr_info("PSB/PST known to be broken - trying ACPI instead\n");
                result = powernow_acpi_init();
        } else {
                result = powernow_decode_bios(fidvidstatus.bits.MFID,
                                fidvidstatus.bits.SVID);
                if (result) {
                        pr_info("Trying ACPI perflib\n");
                        maximum_speed = 0;
                        minimum_speed = -1;
                        latency = 0;
                        result = powernow_acpi_init();
                        if (result) {
                                pr_info("ACPI and legacy methods failed\n");
                        }
                } else {
                        /* SGTC use the bus clock as timer */
                        latency = fixup_sgtc();
                        pr_info("SGTC: %d\n", latency);
                }
        }

        if (result)
                return result;

        pr_info("Minimum speed %d MHz - Maximum speed %d MHz\n",
                minimum_speed/1000, maximum_speed/1000);

        policy->cpuinfo.transition_latency =
                cpufreq_scale(2000000UL, fsb, latency);
        policy->freq_table = powernow_table;

        return 0;
}

static void powernow_cpu_exit(struct cpufreq_policy *policy)
{
#ifdef CONFIG_X86_POWERNOW_K7_ACPI
        if (acpi_processor_perf) {
                acpi_processor_unregister_performance(0);
                free_cpumask_var(acpi_processor_perf->shared_cpu_map);
                kfree(acpi_processor_perf);
        }
#endif

        kfree(powernow_table);
}

static struct cpufreq_driver powernow_driver = {
        .verify         = cpufreq_generic_frequency_table_verify,
        .target_index   = powernow_target,
        .get            = powernow_get,
#ifdef CONFIG_X86_POWERNOW_K7_ACPI
        .bios_limit     = acpi_processor_get_bios_limit,
#endif
        .init           = powernow_cpu_init,
        .exit           = powernow_cpu_exit,
        .name           = "powernow-k7",
};

static int __init powernow_init(void)
{
        if (check_powernow() == 0)
                return -ENODEV;
        return cpufreq_register_driver(&powernow_driver);
}


static void __exit powernow_exit(void)
{
        cpufreq_unregister_driver(&powernow_driver);
}

module_param(acpi_force,  int, 0444);
MODULE_PARM_DESC(acpi_force, "Force ACPI to be used.");

MODULE_AUTHOR("Dave Jones");
MODULE_DESCRIPTION("Powernow driver for AMD K7 processors.");
MODULE_LICENSE("GPL");

late_initcall(powernow_init);
module_exit(powernow_exit);