The Design and Implementation of the FreeBSD Operating System, Second Edition
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sys/dev/acpica/acpi_throttle.c

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    1 /*-
    2  * Copyright (c) 2003-2005 Nate Lawson (SDG)
    3  * Copyright (c) 2001 Michael Smith
    4  * All rights reserved.
    5  *
    6  * Redistribution and use in source and binary forms, with or without
    7  * modification, are permitted provided that the following conditions
    8  * are met:
    9  * 1. Redistributions of source code must retain the above copyright
   10  *      notice, this list of conditions and the following disclaimer.
   11  * 2. Redistributions in binary form must reproduce the above copyright
   12  *      notice, this list of conditions and the following disclaimer in the
   13  *      documentation and/or other materials provided with the distribution.
   14  *
   15  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
   16  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
   17  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
   18  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
   19  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
   20  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
   21  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
   22  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
   23  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
   24  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
   25  * SUCH DAMAGE.
   26  */
   27 
   28 #include <sys/cdefs.h>
   29 __FBSDID("$FreeBSD: releng/10.4/sys/dev/acpica/acpi_throttle.c 283892 2015-06-01 19:26:24Z jkim $");
   30 
   31 #include "opt_acpi.h"
   32 #include <sys/param.h>
   33 #include <sys/bus.h>
   34 #include <sys/cpu.h>
   35 #include <sys/kernel.h>
   36 #include <sys/malloc.h>
   37 #include <sys/module.h>
   38 #include <sys/rman.h>
   39 
   40 #include <machine/bus.h>
   41 
   42 #include <contrib/dev/acpica/include/acpi.h>
   43 
   44 #include <dev/acpica/acpivar.h>
   45 #include <dev/pci/pcivar.h>
   46 
   47 #include "cpufreq_if.h"
   48 
   49 /*
   50  * Throttling provides relative frequency control.  It involves modulating
   51  * the clock so that the CPU is active for only a fraction of the normal
   52  * clock cycle.  It does not change voltage and so is less efficient than
   53  * other mechanisms.  Since it is relative, it can be used in addition to
   54  * absolute cpufreq drivers.  We support the ACPI 2.0 specification.
   55  */
   56 
   57 struct acpi_throttle_softc {
   58         device_t         cpu_dev;
   59         ACPI_HANDLE      cpu_handle;
   60         uint32_t         cpu_p_blk;     /* ACPI P_BLK location */
   61         uint32_t         cpu_p_blk_len; /* P_BLK length (must be 6). */
   62         struct resource *cpu_p_cnt;     /* Throttling control register */
   63         int              cpu_p_type;    /* Resource type for cpu_p_cnt. */
   64         uint32_t         cpu_thr_state; /* Current throttle setting. */
   65 };
   66 
   67 #define THR_GET_REG(reg)                                        \
   68         (bus_space_read_4(rman_get_bustag((reg)),               \
   69                           rman_get_bushandle((reg)), 0))
   70 #define THR_SET_REG(reg, val)                                   \
   71         (bus_space_write_4(rman_get_bustag((reg)),              \
   72                            rman_get_bushandle((reg)), 0, (val)))
   73 
   74 /*
   75  * Speeds are stored in counts, from 1 to CPU_MAX_SPEED, and
   76  * reported to the user in hundredths of a percent.
   77  */
   78 #define CPU_MAX_SPEED           (1 << cpu_duty_width)
   79 #define CPU_SPEED_PERCENT(x)    ((10000 * (x)) / CPU_MAX_SPEED)
   80 #define CPU_SPEED_PRINTABLE(x)  (CPU_SPEED_PERCENT(x) / 10),    \
   81                                 (CPU_SPEED_PERCENT(x) % 10)
   82 #define CPU_P_CNT_THT_EN        (1<<4)
   83 #define CPU_QUIRK_NO_THROTTLE   (1<<1)  /* Throttling is not usable. */
   84 
   85 #define PCI_VENDOR_INTEL        0x8086
   86 #define PCI_DEVICE_82371AB_3    0x7113  /* PIIX4 chipset for quirks. */
   87 #define PCI_REVISION_A_STEP     0
   88 #define PCI_REVISION_B_STEP     1
   89 
   90 static uint32_t cpu_duty_offset;        /* Offset in P_CNT of throttle val. */
   91 static uint32_t cpu_duty_width;         /* Bit width of throttle value. */
   92 static int      thr_rid;                /* Driver-wide resource id. */
   93 static int      thr_quirks;             /* Indicate any hardware bugs. */
   94 
   95 static void     acpi_throttle_identify(driver_t *driver, device_t parent);
   96 static int      acpi_throttle_probe(device_t dev);
   97 static int      acpi_throttle_attach(device_t dev);
   98 static int      acpi_throttle_evaluate(struct acpi_throttle_softc *sc);
   99 static void     acpi_throttle_quirks(struct acpi_throttle_softc *sc);
  100 static int      acpi_thr_settings(device_t dev, struct cf_setting *sets,
  101                     int *count);
  102 static int      acpi_thr_set(device_t dev, const struct cf_setting *set);
  103 static int      acpi_thr_get(device_t dev, struct cf_setting *set);
  104 static int      acpi_thr_type(device_t dev, int *type);
  105 
  106 static device_method_t acpi_throttle_methods[] = {
  107         /* Device interface */
  108         DEVMETHOD(device_identify,      acpi_throttle_identify),
  109         DEVMETHOD(device_probe,         acpi_throttle_probe),
  110         DEVMETHOD(device_attach,        acpi_throttle_attach),
  111 
  112         /* cpufreq interface */
  113         DEVMETHOD(cpufreq_drv_set,      acpi_thr_set),
  114         DEVMETHOD(cpufreq_drv_get,      acpi_thr_get),
  115         DEVMETHOD(cpufreq_drv_type,     acpi_thr_type),
  116         DEVMETHOD(cpufreq_drv_settings, acpi_thr_settings),
  117         DEVMETHOD_END
  118 };
  119 
  120 static driver_t acpi_throttle_driver = {
  121         "acpi_throttle",
  122         acpi_throttle_methods,
  123         sizeof(struct acpi_throttle_softc),
  124 };
  125 
  126 static devclass_t acpi_throttle_devclass;
  127 DRIVER_MODULE(acpi_throttle, cpu, acpi_throttle_driver, acpi_throttle_devclass,
  128     0, 0);
  129 
  130 static void
  131 acpi_throttle_identify(driver_t *driver, device_t parent)
  132 {
  133         ACPI_BUFFER buf;
  134         ACPI_HANDLE handle;
  135         ACPI_OBJECT *obj;
  136 
  137         /* Make sure we're not being doubly invoked. */
  138         if (device_find_child(parent, "acpi_throttle", -1))
  139                 return;
  140 
  141         /* Check for a valid duty width and parent CPU type. */
  142         handle = acpi_get_handle(parent);
  143         if (handle == NULL)
  144                 return;
  145         if (AcpiGbl_FADT.DutyWidth == 0 ||
  146             acpi_get_type(parent) != ACPI_TYPE_PROCESSOR)
  147                 return;
  148 
  149         /*
  150          * Add a child if there's a non-NULL P_BLK and correct length, or
  151          * if the _PTC method is present.
  152          */
  153         buf.Pointer = NULL;
  154         buf.Length = ACPI_ALLOCATE_BUFFER;
  155         if (ACPI_FAILURE(AcpiEvaluateObject(handle, NULL, NULL, &buf)))
  156                 return;
  157         obj = (ACPI_OBJECT *)buf.Pointer;
  158         if ((obj->Processor.PblkAddress && obj->Processor.PblkLength >= 4) ||
  159             ACPI_SUCCESS(AcpiEvaluateObject(handle, "_PTC", NULL, NULL))) {
  160                 if (BUS_ADD_CHILD(parent, 0, "acpi_throttle", -1) == NULL)
  161                         device_printf(parent, "add throttle child failed\n");
  162         }
  163         AcpiOsFree(obj);
  164 }
  165 
  166 static int
  167 acpi_throttle_probe(device_t dev)
  168 {
  169 
  170         if (resource_disabled("acpi_throttle", 0))
  171                 return (ENXIO);
  172 
  173         /*
  174          * On i386 platforms at least, ACPI throttling is accomplished by
  175          * the chipset modulating the STPCLK# pin based on the duty cycle.
  176          * Since p4tcc uses the same mechanism (but internal to the CPU),
  177          * we disable acpi_throttle when p4tcc is also present.
  178          */
  179         if (device_find_child(device_get_parent(dev), "p4tcc", -1) &&
  180             !resource_disabled("p4tcc", 0))
  181                 return (ENXIO);
  182 
  183         device_set_desc(dev, "ACPI CPU Throttling");
  184         return (0);
  185 }
  186 
  187 static int
  188 acpi_throttle_attach(device_t dev)
  189 {
  190         struct acpi_throttle_softc *sc;
  191         struct cf_setting set;
  192         ACPI_BUFFER buf;
  193         ACPI_OBJECT *obj;
  194         ACPI_STATUS status;
  195         int error;
  196 
  197         sc = device_get_softc(dev);
  198         sc->cpu_dev = dev;
  199         sc->cpu_handle = acpi_get_handle(dev);
  200 
  201         buf.Pointer = NULL;
  202         buf.Length = ACPI_ALLOCATE_BUFFER;
  203         status = AcpiEvaluateObject(sc->cpu_handle, NULL, NULL, &buf);
  204         if (ACPI_FAILURE(status)) {
  205                 device_printf(dev, "attach failed to get Processor obj - %s\n",
  206                     AcpiFormatException(status));
  207                 return (ENXIO);
  208         }
  209         obj = (ACPI_OBJECT *)buf.Pointer;
  210         sc->cpu_p_blk = obj->Processor.PblkAddress;
  211         sc->cpu_p_blk_len = obj->Processor.PblkLength;
  212         AcpiOsFree(obj);
  213 
  214         /* If this is the first device probed, check for quirks. */
  215         if (device_get_unit(dev) == 0)
  216                 acpi_throttle_quirks(sc);
  217 
  218         /* Attempt to attach the actual throttling register. */
  219         error = acpi_throttle_evaluate(sc);
  220         if (error)
  221                 return (error);
  222 
  223         /*
  224          * Set our initial frequency to the highest since some systems
  225          * seem to boot with this at the lowest setting.
  226          */
  227         set.freq = 10000;
  228         acpi_thr_set(dev, &set);
  229 
  230         /* Everything went ok, register with cpufreq(4). */
  231         cpufreq_register(dev);
  232         return (0);
  233 }
  234 
  235 static int
  236 acpi_throttle_evaluate(struct acpi_throttle_softc *sc)
  237 {
  238         uint32_t duty_end;
  239         ACPI_BUFFER buf;
  240         ACPI_OBJECT obj;
  241         ACPI_GENERIC_ADDRESS gas;
  242         ACPI_STATUS status;
  243 
  244         /* Get throttling parameters from the FADT.  0 means not supported. */
  245         if (device_get_unit(sc->cpu_dev) == 0) {
  246                 cpu_duty_offset = AcpiGbl_FADT.DutyOffset;
  247                 cpu_duty_width = AcpiGbl_FADT.DutyWidth;
  248         }
  249         if (cpu_duty_width == 0 || (thr_quirks & CPU_QUIRK_NO_THROTTLE) != 0)
  250                 return (ENXIO);
  251 
  252         /* Validate the duty offset/width. */
  253         duty_end = cpu_duty_offset + cpu_duty_width - 1;
  254         if (duty_end > 31) {
  255                 device_printf(sc->cpu_dev,
  256                     "CLK_VAL field overflows P_CNT register\n");
  257                 return (ENXIO);
  258         }
  259         if (cpu_duty_offset <= 4 && duty_end >= 4) {
  260                 device_printf(sc->cpu_dev,
  261                     "CLK_VAL field overlaps THT_EN bit\n");
  262                 return (ENXIO);
  263         }
  264 
  265         /*
  266          * If not present, fall back to using the processor's P_BLK to find
  267          * the P_CNT register.
  268          *
  269          * Note that some systems seem to duplicate the P_BLK pointer
  270          * across multiple CPUs, so not getting the resource is not fatal.
  271          */
  272         buf.Pointer = &obj;
  273         buf.Length = sizeof(obj);
  274         status = AcpiEvaluateObject(sc->cpu_handle, "_PTC", NULL, &buf);
  275         if (ACPI_SUCCESS(status)) {
  276                 if (obj.Buffer.Length < sizeof(ACPI_GENERIC_ADDRESS) + 3) {
  277                         device_printf(sc->cpu_dev, "_PTC buffer too small\n");
  278                         return (ENXIO);
  279                 }
  280                 memcpy(&gas, obj.Buffer.Pointer + 3, sizeof(gas));
  281                 acpi_bus_alloc_gas(sc->cpu_dev, &sc->cpu_p_type, &thr_rid,
  282                     &gas, &sc->cpu_p_cnt, 0);
  283                 if (sc->cpu_p_cnt != NULL && bootverbose) {
  284                         device_printf(sc->cpu_dev, "P_CNT from _PTC %#jx\n",
  285                             gas.Address);
  286                 }
  287         }
  288 
  289         /* If _PTC not present or other failure, try the P_BLK. */
  290         if (sc->cpu_p_cnt == NULL) {
  291                 /* 
  292                  * The spec says P_BLK must be 6 bytes long.  However, some
  293                  * systems use it to indicate a fractional set of features
  294                  * present so we take anything >= 4.
  295                  */
  296                 if (sc->cpu_p_blk_len < 4)
  297                         return (ENXIO);
  298                 gas.Address = sc->cpu_p_blk;
  299                 gas.SpaceId = ACPI_ADR_SPACE_SYSTEM_IO;
  300                 gas.BitWidth = 32;
  301                 acpi_bus_alloc_gas(sc->cpu_dev, &sc->cpu_p_type, &thr_rid,
  302                     &gas, &sc->cpu_p_cnt, 0);
  303                 if (sc->cpu_p_cnt != NULL) {
  304                         if (bootverbose)
  305                                 device_printf(sc->cpu_dev,
  306                                     "P_CNT from P_BLK %#x\n", sc->cpu_p_blk);
  307                 } else {
  308                         device_printf(sc->cpu_dev, "failed to attach P_CNT\n");
  309                         return (ENXIO);
  310                 }
  311         }
  312         thr_rid++;
  313 
  314         return (0);
  315 }
  316 
  317 static void
  318 acpi_throttle_quirks(struct acpi_throttle_softc *sc)
  319 {
  320 #ifdef __i386__
  321         device_t acpi_dev;
  322 
  323         /* Look for various quirks of the PIIX4 part. */
  324         acpi_dev = pci_find_device(PCI_VENDOR_INTEL, PCI_DEVICE_82371AB_3);
  325         if (acpi_dev) {
  326                 switch (pci_get_revid(acpi_dev)) {
  327                 /*
  328                  * Disable throttling control on PIIX4 A and B-step.
  329                  * See specification changes #13 ("Manual Throttle Duty Cycle")
  330                  * and #14 ("Enabling and Disabling Manual Throttle"), plus
  331                  * erratum #5 ("STPCLK# Deassertion Time") from the January
  332                  * 2002 PIIX4 specification update.  Note that few (if any)
  333                  * mobile systems ever used this part.
  334                  */
  335                 case PCI_REVISION_A_STEP:
  336                 case PCI_REVISION_B_STEP:
  337                         thr_quirks |= CPU_QUIRK_NO_THROTTLE;
  338                         break;
  339                 default:
  340                         break;
  341                 }
  342         }
  343 #endif
  344 }
  345 
  346 static int
  347 acpi_thr_settings(device_t dev, struct cf_setting *sets, int *count)
  348 {
  349         int i, speed;
  350 
  351         if (sets == NULL || count == NULL)
  352                 return (EINVAL);
  353         if (*count < CPU_MAX_SPEED)
  354                 return (E2BIG);
  355 
  356         /* Return a list of valid settings for this driver. */
  357         memset(sets, CPUFREQ_VAL_UNKNOWN, sizeof(*sets) * CPU_MAX_SPEED);
  358         for (i = 0, speed = CPU_MAX_SPEED; speed != 0; i++, speed--) {
  359                 sets[i].freq = CPU_SPEED_PERCENT(speed);
  360                 sets[i].dev = dev;
  361         }
  362         *count = CPU_MAX_SPEED;
  363 
  364         return (0);
  365 }
  366 
  367 static int
  368 acpi_thr_set(device_t dev, const struct cf_setting *set)
  369 {
  370         struct acpi_throttle_softc *sc;
  371         uint32_t clk_val, p_cnt, speed;
  372 
  373         if (set == NULL)
  374                 return (EINVAL);
  375         sc = device_get_softc(dev);
  376 
  377         /*
  378          * Validate requested state converts to a duty cycle that is an
  379          * integer from [1 .. CPU_MAX_SPEED].
  380          */
  381         speed = set->freq * CPU_MAX_SPEED / 10000;
  382         if (speed * 10000 != set->freq * CPU_MAX_SPEED ||
  383             speed < 1 || speed > CPU_MAX_SPEED)
  384                 return (EINVAL);
  385 
  386         /* If we're at this setting, don't bother applying it again. */
  387         if (speed == sc->cpu_thr_state)
  388                 return (0);
  389 
  390         /* Get the current P_CNT value and disable throttling */
  391         p_cnt = THR_GET_REG(sc->cpu_p_cnt);
  392         p_cnt &= ~CPU_P_CNT_THT_EN;
  393         THR_SET_REG(sc->cpu_p_cnt, p_cnt);
  394 
  395         /* If we're at maximum speed, that's all */
  396         if (speed < CPU_MAX_SPEED) {
  397                 /* Mask the old CLK_VAL off and OR in the new value */
  398                 clk_val = (CPU_MAX_SPEED - 1) << cpu_duty_offset;
  399                 p_cnt &= ~clk_val;
  400                 p_cnt |= (speed << cpu_duty_offset);
  401 
  402                 /* Write the new P_CNT value and then enable throttling */
  403                 THR_SET_REG(sc->cpu_p_cnt, p_cnt);
  404                 p_cnt |= CPU_P_CNT_THT_EN;
  405                 THR_SET_REG(sc->cpu_p_cnt, p_cnt);
  406         }
  407         sc->cpu_thr_state = speed;
  408 
  409         return (0);
  410 }
  411 
  412 static int
  413 acpi_thr_get(device_t dev, struct cf_setting *set)
  414 {
  415         struct acpi_throttle_softc *sc;
  416         uint32_t p_cnt, clk_val;
  417 
  418         if (set == NULL)
  419                 return (EINVAL);
  420         sc = device_get_softc(dev);
  421 
  422         /* Get the current throttling setting from P_CNT. */
  423         p_cnt = THR_GET_REG(sc->cpu_p_cnt);
  424         clk_val = (p_cnt >> cpu_duty_offset) & (CPU_MAX_SPEED - 1);
  425         sc->cpu_thr_state = clk_val;
  426 
  427         memset(set, CPUFREQ_VAL_UNKNOWN, sizeof(*set));
  428         set->freq = CPU_SPEED_PERCENT(clk_val);
  429         set->dev = dev;
  430 
  431         return (0);
  432 }
  433 
  434 static int
  435 acpi_thr_type(device_t dev, int *type)
  436 {
  437 
  438         if (type == NULL)
  439                 return (EINVAL);
  440 
  441         *type = CPUFREQ_TYPE_RELATIVE;
  442         return (0);
  443 }

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