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cpufreq.c

/*
 * Copyright (C) 2007 PA Semi, Inc
 *
 * Authors: Egor Martovetsky <egor@pasemi.com>
 *        Olof Johansson <olof@lixom.net>
 *
 * Maintained by: Olof Johansson <olof@lixom.net>
 *
 * Based on arch/powerpc/platforms/cell/cbe_cpufreq.c:
 * (C) Copyright IBM Deutschland Entwicklung GmbH 2005
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2, or (at your option)
 * any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
 *
 */

#include <linux/cpufreq.h>
#include <linux/timer.h>

#include <asm/hw_irq.h>
#include <asm/io.h>
#include <asm/prom.h>
#include <asm/time.h>

#define SDCASR_REG            0x0100
#define SDCASR_REG_STRIDE     0x1000
#define SDCPWR_CFGA0_REG      0x0100
#define SDCPWR_PWST0_REG      0x0000
#define SDCPWR_GIZTIME_REG    0x0440

/* SDCPWR_GIZTIME_REG fields */
#define SDCPWR_GIZTIME_GR     0x80000000
#define SDCPWR_GIZTIME_LONGLOCK     0x000000ff

/* Offset of ASR registers from SDC base */
#define SDCASR_OFFSET         0x120000

static void __iomem *sdcpwr_mapbase;
static void __iomem *sdcasr_mapbase;

static DEFINE_MUTEX(pas_switch_mutex);

/* Current astate, is used when waking up from power savings on
 * one core, in case the other core has switched states during
 * the idle time.
 */
static int current_astate;

/* We support 5(A0-A4) power states excluding turbo(A5-A6) modes */
static struct cpufreq_frequency_table pas_freqs[] = {
      {0,   0},
      {1,   0},
      {2,   0},
      {3,   0},
      {4,   0},
      {0,   CPUFREQ_TABLE_END},
};

static struct freq_attr *pas_cpu_freqs_attr[] = {
      &cpufreq_freq_attr_scaling_available_freqs,
      NULL,
};

/*
 * hardware specific functions
 */

static int get_astate_freq(int astate)
{
      u32 ret;
      ret = in_le32(sdcpwr_mapbase + SDCPWR_CFGA0_REG + (astate * 0x10));

      return ret & 0x3f;
}

static int get_cur_astate(int cpu)
{
      u32 ret;

      ret = in_le32(sdcpwr_mapbase + SDCPWR_PWST0_REG);
      ret = (ret >> (cpu * 4)) & 0x7;

      return ret;
}

static int get_gizmo_latency(void)
{
      u32 giztime, ret;

      giztime = in_le32(sdcpwr_mapbase + SDCPWR_GIZTIME_REG);

      /* just provide the upper bound */
      if (giztime & SDCPWR_GIZTIME_GR)
            ret = (giztime & SDCPWR_GIZTIME_LONGLOCK) * 128000;
      else
            ret = (giztime & SDCPWR_GIZTIME_LONGLOCK) * 1000;

      return ret;
}

static void set_astate(int cpu, unsigned int astate)
{
      u64 flags;

      /* Return if called before init has run */
      if (unlikely(!sdcasr_mapbase))
            return;

      local_irq_save(flags);

      out_le32(sdcasr_mapbase + SDCASR_REG + SDCASR_REG_STRIDE*cpu, astate);

      local_irq_restore(flags);
}

void restore_astate(int cpu)
{
      set_astate(cpu, current_astate);
}

/*
 * cpufreq functions
 */

static int pas_cpufreq_cpu_init(struct cpufreq_policy *policy)
{
      const u32 *max_freqp;
      u32 max_freq;
      int i, cur_astate;
      struct resource res;
      struct device_node *cpu, *dn;
      int err = -ENODEV;

      cpu = of_get_cpu_node(policy->cpu, NULL);

      if (!cpu)
            goto out;

      dn = of_find_compatible_node(NULL, "sdc", "1682m-sdc");
      if (!dn)
            goto out;
      err = of_address_to_resource(dn, 0, &res);
      of_node_put(dn);
      if (err)
            goto out;
      sdcasr_mapbase = ioremap(res.start + SDCASR_OFFSET, 0x2000);
      if (!sdcasr_mapbase) {
            err = -EINVAL;
            goto out;
      }

      dn = of_find_compatible_node(NULL, "gizmo", "1682m-gizmo");
      if (!dn) {
            err = -ENODEV;
            goto out_unmap_sdcasr;
      }
      err = of_address_to_resource(dn, 0, &res);
      of_node_put(dn);
      if (err)
            goto out_unmap_sdcasr;
      sdcpwr_mapbase = ioremap(res.start, 0x1000);
      if (!sdcpwr_mapbase) {
            err = -EINVAL;
            goto out_unmap_sdcasr;
      }

      pr_debug("init cpufreq on CPU %d\n", policy->cpu);

      max_freqp = of_get_property(cpu, "clock-frequency", NULL);
      if (!max_freqp) {
            err = -EINVAL;
            goto out_unmap_sdcpwr;
      }

      /* we need the freq in kHz */
      max_freq = *max_freqp / 1000;

      pr_debug("max clock-frequency is at %u kHz\n", max_freq);
      pr_debug("initializing frequency table\n");

      /* initialize frequency table */
      for (i=0; pas_freqs[i].frequency!=CPUFREQ_TABLE_END; i++) {
            pas_freqs[i].frequency = get_astate_freq(pas_freqs[i].index) * 100000;
            pr_debug("%d: %d\n", i, pas_freqs[i].frequency);
      }

      policy->cpuinfo.transition_latency = get_gizmo_latency();

      cur_astate = get_cur_astate(policy->cpu);
      pr_debug("current astate is at %d\n",cur_astate);

      policy->cur = pas_freqs[cur_astate].frequency;
      policy->cpus = cpu_online_map;

      ppc_proc_freq = policy->cur * 1000ul;

      cpufreq_frequency_table_get_attr(pas_freqs, policy->cpu);

      /* this ensures that policy->cpuinfo_min and policy->cpuinfo_max
       * are set correctly
       */
      return cpufreq_frequency_table_cpuinfo(policy, pas_freqs);

out_unmap_sdcpwr:
      iounmap(sdcpwr_mapbase);

out_unmap_sdcasr:
      iounmap(sdcasr_mapbase);
out:
      return err;
}

static int pas_cpufreq_cpu_exit(struct cpufreq_policy *policy)
{
      if (sdcasr_mapbase)
            iounmap(sdcasr_mapbase);
      if (sdcpwr_mapbase)
            iounmap(sdcpwr_mapbase);

      cpufreq_frequency_table_put_attr(policy->cpu);
      return 0;
}

static int pas_cpufreq_verify(struct cpufreq_policy *policy)
{
      return cpufreq_frequency_table_verify(policy, pas_freqs);
}

static int pas_cpufreq_target(struct cpufreq_policy *policy,
                        unsigned int target_freq,
                        unsigned int relation)
{
      struct cpufreq_freqs freqs;
      int pas_astate_new;
      int i;

      cpufreq_frequency_table_target(policy,
                               pas_freqs,
                               target_freq,
                               relation,
                               &pas_astate_new);

      freqs.old = policy->cur;
      freqs.new = pas_freqs[pas_astate_new].frequency;
      freqs.cpu = policy->cpu;

      mutex_lock(&pas_switch_mutex);
      cpufreq_notify_transition(&freqs, CPUFREQ_PRECHANGE);

      pr_debug("setting frequency for cpu %d to %d kHz, 1/%d of max frequency\n",
             policy->cpu,
             pas_freqs[pas_astate_new].frequency,
             pas_freqs[pas_astate_new].index);

      current_astate = pas_astate_new;

      for_each_online_cpu(i)
            set_astate(i, pas_astate_new);

      cpufreq_notify_transition(&freqs, CPUFREQ_POSTCHANGE);
      mutex_unlock(&pas_switch_mutex);

      ppc_proc_freq = freqs.new * 1000ul;
      return 0;
}

static struct cpufreq_driver pas_cpufreq_driver = {
      .name       = "pas-cpufreq",
      .owner            = THIS_MODULE,
      .flags            = CPUFREQ_CONST_LOOPS,
      .init       = pas_cpufreq_cpu_init,
      .exit       = pas_cpufreq_cpu_exit,
      .verify           = pas_cpufreq_verify,
      .target           = pas_cpufreq_target,
      .attr       = pas_cpu_freqs_attr,
};

/*
 * module init and destoy
 */

static int __init pas_cpufreq_init(void)
{
      if (!machine_is_compatible("PA6T-1682M"))
            return -ENODEV;

      return cpufreq_register_driver(&pas_cpufreq_driver);
}

static void __exit pas_cpufreq_exit(void)
{
      cpufreq_unregister_driver(&pas_cpufreq_driver);
}

module_init(pas_cpufreq_init);
module_exit(pas_cpufreq_exit);

MODULE_LICENSE("GPL");
MODULE_AUTHOR("Egor Martovetsky <egor@pasemi.com>, Olof Johansson <olof@lixom.net>");

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