FreeBSD/Linux Kernel Cross Reference
sys/powerpc/cpufreq/dfs.c

     /*-
      * SPDX-License-Identifier: BSD-2-Clause-FreeBSD
      *
      * Copyright (c) 2009 Nathan Whitehorn
      * 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 ``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 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>
    __FBSDID("$FreeBSD$");
    
    #include <sys/param.h>
    #include <sys/systm.h>
    #include <sys/bus.h>
    #include <sys/cpu.h>
    #include <sys/kernel.h>
    #include <sys/module.h>
    
    #include "cpufreq_if.h"
    
    struct dfs_softc {
            device_t dev;
            int      dfs4;
    };
    
    static void     dfs_identify(driver_t *driver, device_t parent);
    static int      dfs_probe(device_t dev);
    static int      dfs_attach(device_t dev);
    static int      dfs_settings(device_t dev, struct cf_setting *sets, int *count);
    static int      dfs_set(device_t dev, const struct cf_setting *set);
    static int      dfs_get(device_t dev, struct cf_setting *set);
    static int      dfs_type(device_t dev, int *type);
    
    static device_method_t dfs_methods[] = {
            /* Device interface */
            DEVMETHOD(device_identify,      dfs_identify),
            DEVMETHOD(device_probe,         dfs_probe),
            DEVMETHOD(device_attach,        dfs_attach),
    
            /* cpufreq interface */
            DEVMETHOD(cpufreq_drv_set,      dfs_set),
            DEVMETHOD(cpufreq_drv_get,      dfs_get),
            DEVMETHOD(cpufreq_drv_type,     dfs_type),
            DEVMETHOD(cpufreq_drv_settings, dfs_settings),
            {0, 0}
    };
    
    static driver_t dfs_driver = {
            "dfs",
            dfs_methods,
            sizeof(struct dfs_softc)
    };
    
    DRIVER_MODULE(dfs, cpu, dfs_driver, 0, 0);
    
    /*
     * Bits of the HID1 register to enable DFS. See page 2-24 of "MPC7450
     * RISC Microprocessor Family Reference Manual", rev. 5.
     */
    
    #define HID1_DFS2       (1UL << 22)
    #define HID1_DFS4       (1UL << 23)
    
    static void
    dfs_identify(driver_t *driver, device_t parent)
    {
            uint16_t vers;
            vers = mfpvr() >> 16;
    
            /* Check for an MPC 7447A or 7448 CPU */
            switch (vers) {
                    case MPC7447A:
                    case MPC7448:
                            break;
                    default:
                            return;
            }
    
            /* Make sure we're not being doubly invoked. */
           if (device_find_child(parent, "dfs", -1) != NULL)
                   return;
   
           /*
            * We attach a child for every CPU since settings need to
            * be performed on every CPU in the SMP case.
            */
           if (BUS_ADD_CHILD(parent, 10, "dfs", -1) == NULL)
                   device_printf(parent, "add dfs child failed\n");
   }
   
   static int
   dfs_probe(device_t dev)
   {
           if (resource_disabled("dfs", 0))
                   return (ENXIO);
   
           device_set_desc(dev, "Dynamic Frequency Switching");
           return (0);
   }
   
   static int
   dfs_attach(device_t dev)
   {
           struct dfs_softc *sc;
           uint16_t vers;
   
           sc = device_get_softc(dev);
           sc->dev = dev;
           sc->dfs4 = 0;
           vers = mfpvr() >> 16;
   
           /* The 7448 supports divide-by-four as well */
           if (vers == MPC7448)
                   sc->dfs4 = 1;
   
           cpufreq_register(dev);
           return (0);
   }
   
   static int
   dfs_settings(device_t dev, struct cf_setting *sets, int *count)
   {
           struct dfs_softc *sc;
           int states;
   
           sc = device_get_softc(dev);
           states = sc->dfs4 ? 3 : 2;
           if (sets == NULL || count == NULL)
                   return (EINVAL);
           if (*count < states)
                   return (E2BIG);
   
           /* Return a list of valid settings for this driver. */
           memset(sets, CPUFREQ_VAL_UNKNOWN, sizeof(*sets) * states);
   
           sets[0].freq = 10000; sets[0].dev = dev;
           sets[1].freq = 5000; sets[1].dev = dev;
           if (sc->dfs4) {
                   sets[2].freq = 2500;
                   sets[2].dev = dev;
           }
           *count = states;
   
           return (0);
   }
   
   static int
   dfs_set(device_t dev, const struct cf_setting *set)
   {
           register_t hid1;
   
           if (set == NULL)
                   return (EINVAL);
   
           hid1 = mfspr(SPR_HID1);
           hid1 &= ~(HID1_DFS2 | HID1_DFS4);
   
           if (set->freq == 5000)
                   hid1 |= HID1_DFS2;
           else if (set->freq == 2500)
                   hid1 |= HID1_DFS4;
   
           /*
            * Now set the HID1 register with new values. Calling sequence
            * taken from page 2-26 of the MPC7450 family CPU manual.
            */
   
           powerpc_sync();
           mtspr(SPR_HID1, hid1);
           powerpc_sync(); isync();
   
           return (0);
   }
   
   static int
   dfs_get(device_t dev, struct cf_setting *set)
   {
           struct dfs_softc *sc;
           register_t hid1;
   
           if (set == NULL)
                   return (EINVAL);
           sc = device_get_softc(dev);
   
           memset(set, CPUFREQ_VAL_UNKNOWN, sizeof(*set));
   
           hid1 = mfspr(SPR_HID1);
   
           set->freq = 10000;
           if (hid1 & HID1_DFS2)
                   set->freq = 5000;
           else if (sc->dfs4 && (hid1 & HID1_DFS4))
                   set->freq = 2500;
   
           set->dev = dev;
   
           return (0);
   }
   
   static int
   dfs_type(device_t dev, int *type)
   {
   
           if (type == NULL)
                   return (EINVAL);
   
           *type = CPUFREQ_TYPE_RELATIVE;
           return (0);
   }

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