/*-
 * Copyright (c) 2003-2005 Nate Lawson (SDG)
 * Copyright (c) 2001 Michael Smith
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *      notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *      notice, this list of conditions and the following disclaimer in the
 *      documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 */

#include <sys/cdefs.h>
#include "opt_acpi.h"
#include <sys/param.h>
#include <sys/bus.h>
#include <sys/cpu.h>
#include <sys/kernel.h>
#include <sys/malloc.h>
#include <sys/module.h>
#include <sys/rman.h>

#include <machine/bus.h>

#include <contrib/dev/acpica/include/acpi.h>

#include <dev/acpica/acpivar.h>
#include <dev/pci/pcivar.h>

#include "cpufreq_if.h"

/*
 * Throttling provides relative frequency control.  It involves modulating
 * the clock so that the CPU is active for only a fraction of the normal
 * clock cycle.  It does not change voltage and so is less efficient than
 * other mechanisms.  Since it is relative, it can be used in addition to
 * absolute cpufreq drivers.  We support the ACPI 2.0 specification.
 */

struct acpi_throttle_softc {
        device_t         cpu_dev;
        ACPI_HANDLE      cpu_handle;
        uint32_t         cpu_p_blk;     /* ACPI P_BLK location */
        uint32_t         cpu_p_blk_len; /* P_BLK length (must be 6). */
        struct resource *cpu_p_cnt;     /* Throttling control register */
        int              cpu_p_type;    /* Resource type for cpu_p_cnt. */
        uint32_t         cpu_thr_state; /* Current throttle setting. */
};

#define THR_GET_REG(reg)                                        \
        (bus_space_read_4(rman_get_bustag((reg)),               \
                          rman_get_bushandle((reg)), 0))
#define THR_SET_REG(reg, val)                                   \
        (bus_space_write_4(rman_get_bustag((reg)),              \
                           rman_get_bushandle((reg)), 0, (val)))

/*
 * Speeds are stored in counts, from 1 to CPU_MAX_SPEED, and
 * reported to the user in hundredths of a percent.
 */
#define CPU_MAX_SPEED           (1 << cpu_duty_width)
#define CPU_SPEED_PERCENT(x)    ((10000 * (x)) / CPU_MAX_SPEED)
#define CPU_SPEED_PRINTABLE(x)  (CPU_SPEED_PERCENT(x) / 10),    \
                                (CPU_SPEED_PERCENT(x) % 10)
#define CPU_P_CNT_THT_EN        (1<<4)
#define CPU_QUIRK_NO_THROTTLE   (1<<1)  /* Throttling is not usable. */

#define PCI_VENDOR_INTEL        0x8086
#define PCI_DEVICE_82371AB_3    0x7113  /* PIIX4 chipset for quirks. */
#define PCI_REVISION_A_STEP     0
#define PCI_REVISION_B_STEP     1

static uint32_t cpu_duty_offset;        /* Offset in P_CNT of throttle val. */
static uint32_t cpu_duty_width;         /* Bit width of throttle value. */
static int      thr_rid;                /* Driver-wide resource id. */
static int      thr_quirks;             /* Indicate any hardware bugs. */

static void     acpi_throttle_identify(driver_t *driver, device_t parent);
static int      acpi_throttle_probe(device_t dev);
static int      acpi_throttle_attach(device_t dev);
static int      acpi_throttle_evaluate(struct acpi_throttle_softc *sc);
static void     acpi_throttle_quirks(struct acpi_throttle_softc *sc);
static int      acpi_thr_settings(device_t dev, struct cf_setting *sets,
                    int *count);
static int      acpi_thr_set(device_t dev, const struct cf_setting *set);
static int      acpi_thr_get(device_t dev, struct cf_setting *set);
static int      acpi_thr_type(device_t dev, int *type);

static device_method_t acpi_throttle_methods[] = {
        /* Device interface */
        DEVMETHOD(device_identify,      acpi_throttle_identify),
        DEVMETHOD(device_probe,         acpi_throttle_probe),
        DEVMETHOD(device_attach,        acpi_throttle_attach),

        /* cpufreq interface */
        DEVMETHOD(cpufreq_drv_set,      acpi_thr_set),
        DEVMETHOD(cpufreq_drv_get,      acpi_thr_get),
        DEVMETHOD(cpufreq_drv_type,     acpi_thr_type),
        DEVMETHOD(cpufreq_drv_settings, acpi_thr_settings),
        DEVMETHOD_END
};

static driver_t acpi_throttle_driver = {
        "acpi_throttle",
        acpi_throttle_methods,
        sizeof(struct acpi_throttle_softc),
};

DRIVER_MODULE(acpi_throttle, cpu, acpi_throttle_driver, 0, 0);

static void
acpi_throttle_identify(driver_t *driver, device_t parent)
{
        ACPI_BUFFER buf;
        ACPI_HANDLE handle;
        ACPI_OBJECT *obj;

        /* Make sure we're not being doubly invoked. */
        if (device_find_child(parent, "acpi_throttle", DEVICE_UNIT_ANY))
                return;

        /* Check for a valid duty width and parent CPU type. */
        handle = acpi_get_handle(parent);
        if (handle == NULL)
                return;
        if (AcpiGbl_FADT.DutyWidth == 0 ||
            acpi_get_type(parent) != ACPI_TYPE_PROCESSOR)
                return;

        /*
         * Add a child if there's a non-NULL P_BLK and correct length, or
         * if the _PTC method is present.
         */
        buf.Pointer = NULL;
        buf.Length = ACPI_ALLOCATE_BUFFER;
        if (ACPI_FAILURE(AcpiEvaluateObject(handle, NULL, NULL, &buf)))
                return;
        obj = (ACPI_OBJECT *)buf.Pointer;
        if ((obj->Processor.PblkAddress && obj->Processor.PblkLength >= 4) ||
            ACPI_SUCCESS(AcpiEvaluateObject(handle, "_PTC", NULL, NULL))) {
                if (BUS_ADD_CHILD(parent, 0, "acpi_throttle",
                    device_get_unit(parent)) == NULL)
                        device_printf(parent, "add throttle child failed\n");
        }
        AcpiOsFree(obj);
}

static int
acpi_throttle_probe(device_t dev)
{

        if (resource_disabled("acpi_throttle", 0))
                return (ENXIO);

        /*
         * On i386 platforms at least, ACPI throttling is accomplished by
         * the chipset modulating the STPCLK# pin based on the duty cycle.
         * Since p4tcc uses the same mechanism (but internal to the CPU),
         * we disable acpi_throttle when p4tcc is also present.
         */
        if (device_find_child(device_get_parent(dev), "p4tcc", DEVICE_UNIT_ANY)
            && !resource_disabled("p4tcc", 0))
                return (ENXIO);

        device_set_desc(dev, "ACPI CPU Throttling");
        return (0);
}

static int
acpi_throttle_attach(device_t dev)
{
        struct acpi_throttle_softc *sc;
        struct cf_setting set;
        ACPI_BUFFER buf;
        ACPI_OBJECT *obj;
        ACPI_STATUS status;
        int error;

        sc = device_get_softc(dev);
        sc->cpu_dev = dev;
        sc->cpu_handle = acpi_get_handle(dev);

        buf.Pointer = NULL;
        buf.Length = ACPI_ALLOCATE_BUFFER;
        status = AcpiEvaluateObject(sc->cpu_handle, NULL, NULL, &buf);
        if (ACPI_FAILURE(status)) {
                device_printf(dev, "attach failed to get Processor obj - %s\n",
                    AcpiFormatException(status));
                return (ENXIO);
        }
        obj = (ACPI_OBJECT *)buf.Pointer;
        sc->cpu_p_blk = obj->Processor.PblkAddress;
        sc->cpu_p_blk_len = obj->Processor.PblkLength;
        AcpiOsFree(obj);

        /* If this is the first device probed, check for quirks. */
        if (device_get_unit(dev) == 0)
                acpi_throttle_quirks(sc);

        /* Attempt to attach the actual throttling register. */
        error = acpi_throttle_evaluate(sc);
        if (error)
                return (error);

        /*
         * Set our initial frequency to the highest since some systems
         * seem to boot with this at the lowest setting.
         */
        set.freq = 10000;
        acpi_thr_set(dev, &set);

        /* Everything went ok, register with cpufreq(4). */
        cpufreq_register(dev);
        return (0);
}

static int
acpi_throttle_evaluate(struct acpi_throttle_softc *sc)
{
        uint32_t duty_end;
        ACPI_BUFFER buf;
        ACPI_OBJECT obj;
        ACPI_GENERIC_ADDRESS gas;
        ACPI_STATUS status;

        /* Get throttling parameters from the FADT.  0 means not supported. */
        if (device_get_unit(sc->cpu_dev) == 0) {
                cpu_duty_offset = AcpiGbl_FADT.DutyOffset;
                cpu_duty_width = AcpiGbl_FADT.DutyWidth;
        }
        if (cpu_duty_width == 0 || (thr_quirks & CPU_QUIRK_NO_THROTTLE) != 0)
                return (ENXIO);

        /* Validate the duty offset/width. */
        duty_end = cpu_duty_offset + cpu_duty_width - 1;
        if (duty_end > 31) {
                device_printf(sc->cpu_dev,
                    "CLK_VAL field overflows P_CNT register\n");
                return (ENXIO);
        }
        if (cpu_duty_offset <= 4 && duty_end >= 4) {
                device_printf(sc->cpu_dev,
                    "CLK_VAL field overlaps THT_EN bit\n");
                return (ENXIO);
        }

        /*
         * If not present, fall back to using the processor's P_BLK to find
         * the P_CNT register.
         *
         * Note that some systems seem to duplicate the P_BLK pointer
         * across multiple CPUs, so not getting the resource is not fatal.
         */
        buf.Pointer = &obj;
        buf.Length = sizeof(obj);
        status = AcpiEvaluateObject(sc->cpu_handle, "_PTC", NULL, &buf);
        if (ACPI_SUCCESS(status)) {
                if (obj.Buffer.Length < sizeof(ACPI_GENERIC_ADDRESS) + 3) {
                        device_printf(sc->cpu_dev, "_PTC buffer too small\n");
                        return (ENXIO);
                }
                memcpy(&gas, obj.Buffer.Pointer + 3, sizeof(gas));
                acpi_bus_alloc_gas(sc->cpu_dev, &sc->cpu_p_type, thr_rid,
                    &gas, &sc->cpu_p_cnt, 0);
                if (sc->cpu_p_cnt != NULL && bootverbose) {
                        device_printf(sc->cpu_dev, "P_CNT from _PTC %#jx\n",
                            gas.Address);
                }
        }

        /* If _PTC not present or other failure, try the P_BLK. */
        if (sc->cpu_p_cnt == NULL) {
                /* 
                 * The spec says P_BLK must be 6 bytes long.  However, some
                 * systems use it to indicate a fractional set of features
                 * present so we take anything >= 4.
                 */
                if (sc->cpu_p_blk_len < 4)
                        return (ENXIO);
                gas.Address = sc->cpu_p_blk;
                gas.SpaceId = ACPI_ADR_SPACE_SYSTEM_IO;
                gas.BitWidth = 32;
                acpi_bus_alloc_gas(sc->cpu_dev, &sc->cpu_p_type, thr_rid,
                    &gas, &sc->cpu_p_cnt, 0);
                if (sc->cpu_p_cnt != NULL) {
                        if (bootverbose)
                                device_printf(sc->cpu_dev,
                                    "P_CNT from P_BLK %#x\n", sc->cpu_p_blk);
                } else {
                        device_printf(sc->cpu_dev, "failed to attach P_CNT\n");
                        return (ENXIO);
                }
        }
        thr_rid++;

        return (0);
}

static void
acpi_throttle_quirks(struct acpi_throttle_softc *sc)
{
#ifdef __i386__
        device_t acpi_dev;

        /* Look for various quirks of the PIIX4 part. */
        acpi_dev = pci_find_device(PCI_VENDOR_INTEL, PCI_DEVICE_82371AB_3);
        if (acpi_dev) {
                switch (pci_get_revid(acpi_dev)) {
                /*
                 * Disable throttling control on PIIX4 A and B-step.
                 * See specification changes #13 ("Manual Throttle Duty Cycle")
                 * and #14 ("Enabling and Disabling Manual Throttle"), plus
                 * erratum #5 ("STPCLK# Deassertion Time") from the January
                 * 2002 PIIX4 specification update.  Note that few (if any)
                 * mobile systems ever used this part.
                 */
                case PCI_REVISION_A_STEP:
                case PCI_REVISION_B_STEP:
                        thr_quirks |= CPU_QUIRK_NO_THROTTLE;
                        break;
                default:
                        break;
                }
        }
#endif
}

static int
acpi_thr_settings(device_t dev, struct cf_setting *sets, int *count)
{
        int i, speed;

        if (sets == NULL || count == NULL)
                return (EINVAL);
        if (*count < CPU_MAX_SPEED)
                return (E2BIG);

        /* Return a list of valid settings for this driver. */
        memset(sets, CPUFREQ_VAL_UNKNOWN, sizeof(*sets) * CPU_MAX_SPEED);
        for (i = 0, speed = CPU_MAX_SPEED; speed != 0; i++, speed--) {
                sets[i].freq = CPU_SPEED_PERCENT(speed);
                sets[i].dev = dev;
        }
        *count = CPU_MAX_SPEED;

        return (0);
}

static int
acpi_thr_set(device_t dev, const struct cf_setting *set)
{
        struct acpi_throttle_softc *sc;
        uint32_t clk_val, p_cnt, speed;

        if (set == NULL)
                return (EINVAL);
        sc = device_get_softc(dev);

        /*
         * Validate requested state converts to a duty cycle that is an
         * integer from [1 .. CPU_MAX_SPEED].
         */
        speed = set->freq * CPU_MAX_SPEED / 10000;
        if (speed * 10000 != set->freq * CPU_MAX_SPEED ||
            speed < 1 || speed > CPU_MAX_SPEED)
                return (EINVAL);

        /* If we're at this setting, don't bother applying it again. */
        if (speed == sc->cpu_thr_state)
                return (0);

        /* Get the current P_CNT value and disable throttling */
        p_cnt = THR_GET_REG(sc->cpu_p_cnt);
        p_cnt &= ~CPU_P_CNT_THT_EN;
        THR_SET_REG(sc->cpu_p_cnt, p_cnt);

        /* If we're at maximum speed, that's all */
        if (speed < CPU_MAX_SPEED) {
                /* Mask the old CLK_VAL off and OR in the new value */
                clk_val = (CPU_MAX_SPEED - 1) << cpu_duty_offset;
                p_cnt &= ~clk_val;
                p_cnt |= (speed << cpu_duty_offset);

                /* Write the new P_CNT value and then enable throttling */
                THR_SET_REG(sc->cpu_p_cnt, p_cnt);
                p_cnt |= CPU_P_CNT_THT_EN;
                THR_SET_REG(sc->cpu_p_cnt, p_cnt);
        }
        sc->cpu_thr_state = speed;

        return (0);
}

static int
acpi_thr_get(device_t dev, struct cf_setting *set)
{
        struct acpi_throttle_softc *sc;
        uint32_t p_cnt, clk_val;

        if (set == NULL)
                return (EINVAL);
        sc = device_get_softc(dev);

        /* Get the current throttling setting from P_CNT. */
        p_cnt = THR_GET_REG(sc->cpu_p_cnt);
        clk_val = (p_cnt >> cpu_duty_offset) & (CPU_MAX_SPEED - 1);
        sc->cpu_thr_state = clk_val;

        memset(set, CPUFREQ_VAL_UNKNOWN, sizeof(*set));
        set->freq = CPU_SPEED_PERCENT(clk_val);
        set->dev = dev;

        return (0);
}

static int
acpi_thr_type(device_t dev, int *type)
{

        if (type == NULL)
                return (EINVAL);

        *type = CPUFREQ_TYPE_RELATIVE;
        return (0);
}