The Design and Implementation of the FreeBSD Operating System, Second Edition
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FreeBSD/Linux Kernel Cross Reference
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/5.4/sys/dev/acpica/acpi_throttle.c 142509 2005-02-25 21:43:38Z njl $");
   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 "acpi.h"
   43 #include <dev/acpica/acpivar.h>
   44 #include <dev/pci/pcivar.h>
   45 
   46 #include "cpufreq_if.h"
   47 
   48 /*
   49  * Throttling provides relative frequency control.  It involves modulating
   50  * the clock so that the CPU is active for only a fraction of the normal
   51  * clock cycle.  It does not change voltage and so is less efficient than
   52  * other mechanisms.  Since it is relative, it can be used in addition to
   53  * absolute cpufreq drivers.  We support the ACPI 2.0 specification.
   54  */
   55 
   56 struct acpi_throttle_softc {
   57         device_t         cpu_dev;
   58         ACPI_HANDLE      cpu_handle;
   59         uint32_t         cpu_p_blk;     /* ACPI P_BLK location */
   60         uint32_t         cpu_p_blk_len; /* P_BLK length (must be 6). */
   61         struct resource *cpu_p_cnt;     /* Throttling control register */
   62         int              cpu_p_type;    /* Resource type for cpu_p_cnt. */
   63         uint32_t         cpu_thr_state; /* Current throttle setting. */
   64 };
   65 
   66 #define THR_GET_REG(reg)                                        \
   67         (bus_space_read_4(rman_get_bustag((reg)),               \
   68                           rman_get_bushandle((reg)), 0))
   69 #define THR_SET_REG(reg, val)                                   \
   70         (bus_space_write_4(rman_get_bustag((reg)),              \
   71                            rman_get_bushandle((reg)), 0, (val)))
   72 
   73 /*
   74  * Speeds are stored in counts, from 1 to CPU_MAX_SPEED, and
   75  * reported to the user in hundredths of a percent.
   76  */
   77 #define CPU_MAX_SPEED           (1 << cpu_duty_width)
   78 #define CPU_SPEED_PERCENT(x)    ((10000 * (x)) / CPU_MAX_SPEED)
   79 #define CPU_SPEED_PRINTABLE(x)  (CPU_SPEED_PERCENT(x) / 10),    \
   80                                 (CPU_SPEED_PERCENT(x) % 10)
   81 #define CPU_P_CNT_THT_EN        (1<<4)
   82 #define CPU_QUIRK_NO_THROTTLE   (1<<1)  /* Throttling is not usable. */
   83 
   84 #define PCI_VENDOR_INTEL        0x8086
   85 #define PCI_DEVICE_82371AB_3    0x7113  /* PIIX4 chipset for quirks. */
   86 #define PCI_REVISION_A_STEP     0
   87 #define PCI_REVISION_B_STEP     1
   88 
   89 static uint32_t cpu_duty_offset;        /* Offset in P_CNT of throttle val. */
   90 static uint32_t cpu_duty_width;         /* Bit width of throttle value. */
   91 static int      thr_rid;                /* Driver-wide resource id. */
   92 static int      thr_quirks;             /* Indicate any hardware bugs. */
   93 
   94 static void     acpi_throttle_identify(driver_t *driver, device_t parent);
   95 static int      acpi_throttle_probe(device_t dev);
   96 static int      acpi_throttle_attach(device_t dev);
   97 static int      acpi_throttle_evaluate(struct acpi_throttle_softc *sc);
   98 static int      acpi_throttle_quirks(struct acpi_throttle_softc *sc);
   99 static int      acpi_thr_settings(device_t dev, struct cf_setting *sets,
  100                     int *count);
  101 static int      acpi_thr_set(device_t dev, const struct cf_setting *set);
  102 static int      acpi_thr_get(device_t dev, struct cf_setting *set);
  103 static int      acpi_thr_type(device_t dev, int *type);
  104 
  105 static device_method_t acpi_throttle_methods[] = {
  106         /* Device interface */
  107         DEVMETHOD(device_identify,      acpi_throttle_identify),
  108         DEVMETHOD(device_probe,         acpi_throttle_probe),
  109         DEVMETHOD(device_attach,        acpi_throttle_attach),
  110 
  111         /* cpufreq interface */
  112         DEVMETHOD(cpufreq_drv_set,      acpi_thr_set),
  113         DEVMETHOD(cpufreq_drv_get,      acpi_thr_get),
  114         DEVMETHOD(cpufreq_drv_type,     acpi_thr_type),
  115         DEVMETHOD(cpufreq_drv_settings, acpi_thr_settings),
  116         {0, 0}
  117 };
  118 
  119 static driver_t acpi_throttle_driver = {
  120         "acpi_throttle",
  121         acpi_throttle_methods,
  122         sizeof(struct acpi_throttle_softc),
  123 };
  124 
  125 static devclass_t acpi_throttle_devclass;
  126 DRIVER_MODULE(acpi_throttle, cpu, acpi_throttle_driver, acpi_throttle_devclass,
  127     0, 0);
  128 
  129 static void
  130 acpi_throttle_identify(driver_t *driver, device_t parent)
  131 {
  132         ACPI_BUFFER buf;
  133         ACPI_HANDLE handle;
  134         ACPI_OBJECT *obj;
  135 
  136         /* Make sure we're not being doubly invoked. */
  137         if (device_find_child(parent, "acpi_throttle", -1) != NULL)
  138                 return;
  139 
  140         /* Check for a valid duty width and parent CPU type. */
  141         handle = acpi_get_handle(parent);
  142         if (handle == NULL)
  143                 return;
  144         if (AcpiGbl_FADT->DutyWidth == 0 ||
  145             acpi_get_type(parent) != ACPI_TYPE_PROCESSOR)
  146                 return;
  147 
  148         /*
  149          * Add a child if there's a non-NULL P_BLK and correct length, or
  150          * if the _PTC method is present.
  151          */
  152         buf.Pointer = NULL;
  153         buf.Length = ACPI_ALLOCATE_BUFFER;
  154         if (ACPI_FAILURE(AcpiEvaluateObject(handle, NULL, NULL, &buf)))
  155                 return;
  156         obj = (ACPI_OBJECT *)buf.Pointer;
  157         if ((obj->Processor.PblkAddress && obj->Processor.PblkLength >= 4) ||
  158             ACPI_SUCCESS(AcpiEvaluateObject(handle, "_PTC", NULL, NULL))) {
  159                 if (BUS_ADD_CHILD(parent, 0, "acpi_throttle", -1) == NULL)
  160                         device_printf(parent, "add throttle child failed\n");
  161         }
  162         AcpiOsFree(obj);
  163 }
  164 
  165 static int
  166 acpi_throttle_probe(device_t dev)
  167 {
  168 
  169         if (resource_disabled("acpi_throttle", 0))
  170                 return (ENXIO);
  171 
  172         device_set_desc(dev, "ACPI CPU Throttling");
  173         return (0);
  174 }
  175 
  176 static int
  177 acpi_throttle_attach(device_t dev)
  178 {
  179         struct acpi_throttle_softc *sc;
  180         ACPI_BUFFER buf;
  181         ACPI_OBJECT *obj;
  182         ACPI_STATUS status;
  183         int error;
  184 
  185         sc = device_get_softc(dev);
  186         sc->cpu_dev = dev;
  187         sc->cpu_handle = acpi_get_handle(dev);
  188 
  189         buf.Pointer = NULL;
  190         buf.Length = ACPI_ALLOCATE_BUFFER;
  191         status = AcpiEvaluateObject(sc->cpu_handle, NULL, NULL, &buf);
  192         if (ACPI_FAILURE(status)) {
  193                 device_printf(dev, "attach failed to get Processor obj - %s\n",
  194                     AcpiFormatException(status));
  195                 return (ENXIO);
  196         }
  197         obj = (ACPI_OBJECT *)buf.Pointer;
  198         sc->cpu_p_blk = obj->Processor.PblkAddress;
  199         sc->cpu_p_blk_len = obj->Processor.PblkLength;
  200         AcpiOsFree(obj);
  201 
  202         /* If this is the first device probed, check for quirks. */
  203         if (device_get_unit(dev) == 0)
  204                 acpi_throttle_quirks(sc);
  205 
  206         /* Attempt to attach the actual throttling register. */
  207         error = acpi_throttle_evaluate(sc);
  208         if (error)
  209                 return (error);
  210 
  211         /* Everything went ok, register with cpufreq(4). */
  212         cpufreq_register(dev);
  213         return (0);
  214 }
  215 
  216 static int
  217 acpi_throttle_evaluate(struct acpi_throttle_softc *sc)
  218 {
  219         uint32_t duty_end;
  220         ACPI_BUFFER buf;
  221         ACPI_OBJECT obj;
  222         ACPI_GENERIC_ADDRESS gas;
  223         ACPI_STATUS status;
  224 
  225         /* Get throttling parameters from the FADT.  0 means not supported. */
  226         if (device_get_unit(sc->cpu_dev) == 0) {
  227                 cpu_duty_offset = AcpiGbl_FADT->DutyOffset;
  228                 cpu_duty_width = AcpiGbl_FADT->DutyWidth;
  229         }
  230         if (cpu_duty_width == 0 || (thr_quirks & CPU_QUIRK_NO_THROTTLE) != 0)
  231                 return (ENXIO);
  232 
  233         /* Validate the duty offset/width. */
  234         duty_end = cpu_duty_offset + cpu_duty_width - 1;
  235         if (duty_end > 31) {
  236                 device_printf(sc->cpu_dev,
  237                     "CLK_VAL field overflows P_CNT register\n");
  238                 return (ENXIO);
  239         }
  240         if (cpu_duty_offset <= 4 && duty_end >= 4) {
  241                 device_printf(sc->cpu_dev,
  242                     "CLK_VAL field overlaps THT_EN bit\n");
  243                 return (ENXIO);
  244         }
  245 
  246         /*
  247          * If not present, fall back to using the processor's P_BLK to find
  248          * the P_CNT register.
  249          *
  250          * Note that some systems seem to duplicate the P_BLK pointer
  251          * across multiple CPUs, so not getting the resource is not fatal.
  252          */
  253         buf.Pointer = &obj;
  254         buf.Length = sizeof(obj);
  255         status = AcpiEvaluateObject(sc->cpu_handle, "_PTC", NULL, &buf);
  256         if (ACPI_SUCCESS(status)) {
  257                 if (obj.Buffer.Length < sizeof(ACPI_GENERIC_ADDRESS) + 3) {
  258                         device_printf(sc->cpu_dev, "_PTC buffer too small\n");
  259                         return (ENXIO);
  260                 }
  261                 memcpy(&gas, obj.Buffer.Pointer + 3, sizeof(gas));
  262                 acpi_bus_alloc_gas(sc->cpu_dev, &sc->cpu_p_type, &thr_rid,
  263                     &gas, &sc->cpu_p_cnt);
  264                 if (sc->cpu_p_cnt != NULL && bootverbose) {
  265                         device_printf(sc->cpu_dev, "P_CNT from _PTC %#jx\n",
  266                             gas.Address);
  267                 }
  268         }
  269 
  270         /* If _PTC not present or other failure, try the P_BLK. */
  271         if (sc->cpu_p_cnt == NULL) {
  272                 /* 
  273                  * The spec says P_BLK must be 6 bytes long.  However, some
  274                  * systems use it to indicate a fractional set of features
  275                  * present so we take anything >= 4.
  276                  */
  277                 if (sc->cpu_p_blk_len < 4)
  278                         return (ENXIO);
  279                 gas.Address = sc->cpu_p_blk;
  280                 gas.AddressSpaceId = ACPI_ADR_SPACE_SYSTEM_IO;
  281                 gas.RegisterBitWidth = 32;
  282                 acpi_bus_alloc_gas(sc->cpu_dev, &sc->cpu_p_type, &thr_rid,
  283                     &gas, &sc->cpu_p_cnt);
  284                 if (sc->cpu_p_cnt != NULL) {
  285                         if (bootverbose)
  286                                 device_printf(sc->cpu_dev,
  287                                     "P_CNT from P_BLK %#x\n", sc->cpu_p_blk);
  288                 } else {
  289                         device_printf(sc->cpu_dev, "failed to attach P_CNT\n");
  290                         return (ENXIO);
  291                 }
  292         }
  293         thr_rid++;
  294 
  295         return (0);
  296 }
  297 
  298 static int
  299 acpi_throttle_quirks(struct acpi_throttle_softc *sc)
  300 {
  301         device_t acpi_dev;
  302 
  303         /* Look for various quirks of the PIIX4 part. */
  304         acpi_dev = pci_find_device(PCI_VENDOR_INTEL, PCI_DEVICE_82371AB_3);
  305         if (acpi_dev) {
  306                 switch (pci_get_revid(acpi_dev)) {
  307                 /*
  308                  * Disable throttling control on PIIX4 A and B-step.
  309                  * See specification changes #13 ("Manual Throttle Duty Cycle")
  310                  * and #14 ("Enabling and Disabling Manual Throttle"), plus
  311                  * erratum #5 ("STPCLK# Deassertion Time") from the January
  312                  * 2002 PIIX4 specification update.  Note that few (if any)
  313                  * mobile systems ever used this part.
  314                  */
  315                 case PCI_REVISION_A_STEP:
  316                 case PCI_REVISION_B_STEP:
  317                         thr_quirks |= CPU_QUIRK_NO_THROTTLE;
  318                         break;
  319                 default:
  320                         break;
  321                 }
  322         }
  323 
  324         return (0);
  325 }
  326 
  327 static int
  328 acpi_thr_settings(device_t dev, struct cf_setting *sets, int *count)
  329 {
  330         struct acpi_throttle_softc *sc;
  331         int i, speed;
  332 
  333         sc = device_get_softc(dev);
  334         if (sets == NULL || count == NULL)
  335                 return (EINVAL);
  336         if (*count < CPU_MAX_SPEED)
  337                 return (E2BIG);
  338 
  339         /* Return a list of valid settings for this driver. */
  340         memset(sets, CPUFREQ_VAL_UNKNOWN, sizeof(*sets) * CPU_MAX_SPEED);
  341         for (i = 0, speed = CPU_MAX_SPEED; speed != 0; i++, speed--) {
  342                 sets[i].freq = CPU_SPEED_PERCENT(speed);
  343                 sets[i].dev = dev;
  344         }
  345         *count = CPU_MAX_SPEED;
  346 
  347         return (0);
  348 }
  349 
  350 static int
  351 acpi_thr_set(device_t dev, const struct cf_setting *set)
  352 {
  353         struct acpi_throttle_softc *sc;
  354         uint32_t clk_val, p_cnt, speed;
  355 
  356         if (set == NULL)
  357                 return (EINVAL);
  358         sc = device_get_softc(dev);
  359 
  360         /*
  361          * Validate requested state converts to a duty cycle that is an
  362          * integer from [1 .. CPU_MAX_SPEED].
  363          */
  364         speed = set->freq * CPU_MAX_SPEED / 10000;
  365         if (speed * 10000 != set->freq * CPU_MAX_SPEED ||
  366             speed < 1 || speed > CPU_MAX_SPEED)
  367                 return (EINVAL);
  368 
  369         /* If we're at this setting, don't bother applying it again. */
  370         if (speed == sc->cpu_thr_state)
  371                 return (0);
  372 
  373         /* Get the current P_CNT value and disable throttling */
  374         p_cnt = THR_GET_REG(sc->cpu_p_cnt);
  375         p_cnt &= ~CPU_P_CNT_THT_EN;
  376         THR_SET_REG(sc->cpu_p_cnt, p_cnt);
  377 
  378         /* If we're at maximum speed, that's all */
  379         if (speed < CPU_MAX_SPEED) {
  380                 /* Mask the old CLK_VAL off and OR in the new value */
  381                 clk_val = (CPU_MAX_SPEED - 1) << cpu_duty_offset;
  382                 p_cnt &= ~clk_val;
  383                 p_cnt |= (speed << cpu_duty_offset);
  384 
  385                 /* Write the new P_CNT value and then enable throttling */
  386                 THR_SET_REG(sc->cpu_p_cnt, p_cnt);
  387                 p_cnt |= CPU_P_CNT_THT_EN;
  388                 THR_SET_REG(sc->cpu_p_cnt, p_cnt);
  389         }
  390         sc->cpu_thr_state = speed;
  391 
  392         return (0);
  393 }
  394 
  395 static int
  396 acpi_thr_get(device_t dev, struct cf_setting *set)
  397 {
  398         struct acpi_throttle_softc *sc;
  399         uint32_t p_cnt, clk_val;
  400 
  401         if (set == NULL)
  402                 return (EINVAL);
  403         sc = device_get_softc(dev);
  404 
  405         /* Get the current throttling setting from P_CNT. */
  406         p_cnt = THR_GET_REG(sc->cpu_p_cnt);
  407         clk_val = (p_cnt >> cpu_duty_offset) & (CPU_MAX_SPEED - 1);
  408         sc->cpu_thr_state = clk_val;
  409 
  410         memset(set, CPUFREQ_VAL_UNKNOWN, sizeof(*set));
  411         set->freq = CPU_SPEED_PERCENT(clk_val);
  412         set->dev = dev;
  413 
  414         return (0);
  415 }
  416 
  417 static int
  418 acpi_thr_type(device_t dev, int *type)
  419 {
  420 
  421         if (type == NULL)
  422                 return (EINVAL);
  423 
  424         *type = CPUFREQ_TYPE_RELATIVE;
  425         return (0);
  426 }

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