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acpi-cpufreq.c

/*
 * arch/ia64/kernel/cpufreq/acpi-cpufreq.c
 * This file provides the ACPI based P-state support. This
 * module works with generic cpufreq infrastructure. Most of
 * the code is based on i386 version
 * (arch/i386/kernel/cpu/cpufreq/acpi-cpufreq.c)
 *
 * Copyright (C) 2005 Intel Corp
 *      Venkatesh Pallipadi <venkatesh.pallipadi@intel.com>
 */

#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/init.h>
#include <linux/cpufreq.h>
#include <linux/proc_fs.h>
#include <linux/seq_file.h>
#include <asm/io.h>
#include <asm/uaccess.h>
#include <asm/pal.h>

#include <linux/acpi.h>
#include <acpi/processor.h>

#define dprintk(msg...) cpufreq_debug_printk(CPUFREQ_DEBUG_DRIVER, "acpi-cpufreq", msg)

MODULE_AUTHOR("Venkatesh Pallipadi");
MODULE_DESCRIPTION("ACPI Processor P-States Driver");
MODULE_LICENSE("GPL");


struct cpufreq_acpi_io {
      struct acpi_processor_performance   acpi_data;
      struct cpufreq_frequency_table            *freq_table;
      unsigned int                        resume;
};

static struct cpufreq_acpi_io *acpi_io_data[NR_CPUS];

static struct cpufreq_driver acpi_cpufreq_driver;


static int
processor_set_pstate (
      u32   value)
{
      s64 retval;

      dprintk("processor_set_pstate\n");

      retval = ia64_pal_set_pstate((u64)value);

      if (retval) {
            dprintk("Failed to set freq to 0x%x, with error 0x%x\n",
                    value, retval);
            return -ENODEV;
      }
      return (int)retval;
}


static int
processor_get_pstate (
      u32   *value)
{
      u64   pstate_index = 0;
      s64   retval;

      dprintk("processor_get_pstate\n");

      retval = ia64_pal_get_pstate(&pstate_index,
                                   PAL_GET_PSTATE_TYPE_INSTANT);
      *value = (u32) pstate_index;

      if (retval)
            dprintk("Failed to get current freq with "
                    "error 0x%x, idx 0x%x\n", retval, *value);

      return (int)retval;
}


/* To be used only after data->acpi_data is initialized */
static unsigned
extract_clock (
      struct cpufreq_acpi_io *data,
      unsigned value,
      unsigned int cpu)
{
      unsigned long i;

      dprintk("extract_clock\n");

      for (i = 0; i < data->acpi_data.state_count; i++) {
            if (value == data->acpi_data.states[i].status)
                  return data->acpi_data.states[i].core_frequency;
      }
      return data->acpi_data.states[i-1].core_frequency;
}


static unsigned int
processor_get_freq (
      struct cpufreq_acpi_io  *data,
      unsigned int            cpu)
{
      int               ret = 0;
      u32               value = 0;
      cpumask_t         saved_mask;
      unsigned long           clock_freq;

      dprintk("processor_get_freq\n");

      saved_mask = current->cpus_allowed;
      set_cpus_allowed(current, cpumask_of_cpu(cpu));
      if (smp_processor_id() != cpu)
            goto migrate_end;

      /* processor_get_pstate gets the instantaneous frequency */
      ret = processor_get_pstate(&value);

      if (ret) {
            set_cpus_allowed(current, saved_mask);
            printk(KERN_WARNING "get performance failed with error %d\n",
                   ret);
            ret = 0;
            goto migrate_end;
      }
      clock_freq = extract_clock(data, value, cpu);
      ret = (clock_freq*1000);

migrate_end:
      set_cpus_allowed(current, saved_mask);
      return ret;
}


static int
processor_set_freq (
      struct cpufreq_acpi_io  *data,
      unsigned int            cpu,
      int               state)
{
      int               ret = 0;
      u32               value = 0;
      struct cpufreq_freqs    cpufreq_freqs;
      cpumask_t         saved_mask;
      int               retval;

      dprintk("processor_set_freq\n");

      saved_mask = current->cpus_allowed;
      set_cpus_allowed(current, cpumask_of_cpu(cpu));
      if (smp_processor_id() != cpu) {
            retval = -EAGAIN;
            goto migrate_end;
      }

      if (state == data->acpi_data.state) {
            if (unlikely(data->resume)) {
                  dprintk("Called after resume, resetting to P%d\n", state);
                  data->resume = 0;
            } else {
                  dprintk("Already at target state (P%d)\n", state);
                  retval = 0;
                  goto migrate_end;
            }
      }

      dprintk("Transitioning from P%d to P%d\n",
            data->acpi_data.state, state);

      /* cpufreq frequency struct */
      cpufreq_freqs.cpu = cpu;
      cpufreq_freqs.old = data->freq_table[data->acpi_data.state].frequency;
      cpufreq_freqs.new = data->freq_table[state].frequency;

      /* notify cpufreq */
      cpufreq_notify_transition(&cpufreq_freqs, CPUFREQ_PRECHANGE);

      /*
       * First we write the target state's 'control' value to the
       * control_register.
       */

      value = (u32) data->acpi_data.states[state].control;

      dprintk("Transitioning to state: 0x%08x\n", value);

      ret = processor_set_pstate(value);
      if (ret) {
            unsigned int tmp = cpufreq_freqs.new;
            cpufreq_notify_transition(&cpufreq_freqs, CPUFREQ_POSTCHANGE);
            cpufreq_freqs.new = cpufreq_freqs.old;
            cpufreq_freqs.old = tmp;
            cpufreq_notify_transition(&cpufreq_freqs, CPUFREQ_PRECHANGE);
            cpufreq_notify_transition(&cpufreq_freqs, CPUFREQ_POSTCHANGE);
            printk(KERN_WARNING "Transition failed with error %d\n", ret);
            retval = -ENODEV;
            goto migrate_end;
      }

      cpufreq_notify_transition(&cpufreq_freqs, CPUFREQ_POSTCHANGE);

      data->acpi_data.state = state;

      retval = 0;

migrate_end:
      set_cpus_allowed(current, saved_mask);
      return (retval);
}


static unsigned int
acpi_cpufreq_get (
      unsigned int            cpu)
{
      struct cpufreq_acpi_io *data = acpi_io_data[cpu];

      dprintk("acpi_cpufreq_get\n");

      return processor_get_freq(data, cpu);
}


static int
acpi_cpufreq_target (
      struct cpufreq_policy   *policy,
      unsigned int target_freq,
      unsigned int relation)
{
      struct cpufreq_acpi_io *data = acpi_io_data[policy->cpu];
      unsigned int next_state = 0;
      unsigned int result = 0;

      dprintk("acpi_cpufreq_setpolicy\n");

      result = cpufreq_frequency_table_target(policy,
                  data->freq_table, target_freq, relation, &next_state);
      if (result)
            return (result);

      result = processor_set_freq(data, policy->cpu, next_state);

      return (result);
}


static int
acpi_cpufreq_verify (
      struct cpufreq_policy   *policy)
{
      unsigned int result = 0;
      struct cpufreq_acpi_io *data = acpi_io_data[policy->cpu];

      dprintk("acpi_cpufreq_verify\n");

      result = cpufreq_frequency_table_verify(policy,
                  data->freq_table);

      return (result);
}


static int
acpi_cpufreq_cpu_init (
      struct cpufreq_policy   *policy)
{
      unsigned int            i;
      unsigned int            cpu = policy->cpu;
      struct cpufreq_acpi_io  *data;
      unsigned int            result = 0;

      dprintk("acpi_cpufreq_cpu_init\n");

      data = kzalloc(sizeof(struct cpufreq_acpi_io), GFP_KERNEL);
      if (!data)
            return (-ENOMEM);

      acpi_io_data[cpu] = data;

      result = acpi_processor_register_performance(&data->acpi_data, cpu);

      if (result)
            goto err_free;

      /* capability check */
      if (data->acpi_data.state_count <= 1) {
            dprintk("No P-States\n");
            result = -ENODEV;
            goto err_unreg;
      }

      if ((data->acpi_data.control_register.space_id !=
                              ACPI_ADR_SPACE_FIXED_HARDWARE) ||
          (data->acpi_data.status_register.space_id !=
                              ACPI_ADR_SPACE_FIXED_HARDWARE)) {
            dprintk("Unsupported address space [%d, %d]\n",
                  (u32) (data->acpi_data.control_register.space_id),
                  (u32) (data->acpi_data.status_register.space_id));
            result = -ENODEV;
            goto err_unreg;
      }

      /* alloc freq_table */
      data->freq_table = kmalloc(sizeof(struct cpufreq_frequency_table) *
                                 (data->acpi_data.state_count + 1),
                                 GFP_KERNEL);
      if (!data->freq_table) {
            result = -ENOMEM;
            goto err_unreg;
      }

      /* detect transition latency */
      policy->cpuinfo.transition_latency = 0;
      for (i=0; i<data->acpi_data.state_count; i++) {
            if ((data->acpi_data.states[i].transition_latency * 1000) >
                policy->cpuinfo.transition_latency) {
                  policy->cpuinfo.transition_latency =
                      data->acpi_data.states[i].transition_latency * 1000;
            }
      }
      policy->cur = processor_get_freq(data, policy->cpu);

      /* table init */
      for (i = 0; i <= data->acpi_data.state_count; i++)
      {
            data->freq_table[i].index = i;
            if (i < data->acpi_data.state_count) {
                  data->freq_table[i].frequency =
                        data->acpi_data.states[i].core_frequency * 1000;
            } else {
                  data->freq_table[i].frequency = CPUFREQ_TABLE_END;
            }
      }

      result = cpufreq_frequency_table_cpuinfo(policy, data->freq_table);
      if (result) {
            goto err_freqfree;
      }

      /* notify BIOS that we exist */
      acpi_processor_notify_smm(THIS_MODULE);

      printk(KERN_INFO "acpi-cpufreq: CPU%u - ACPI performance management "
             "activated.\n", cpu);

      for (i = 0; i < data->acpi_data.state_count; i++)
            dprintk("     %cP%d: %d MHz, %d mW, %d uS, %d uS, 0x%x 0x%x\n",
                  (i == data->acpi_data.state?'*':' '), i,
                  (u32) data->acpi_data.states[i].core_frequency,
                  (u32) data->acpi_data.states[i].power,
                  (u32) data->acpi_data.states[i].transition_latency,
                  (u32) data->acpi_data.states[i].bus_master_latency,
                  (u32) data->acpi_data.states[i].status,
                  (u32) data->acpi_data.states[i].control);

      cpufreq_frequency_table_get_attr(data->freq_table, policy->cpu);

      /* the first call to ->target() should result in us actually
       * writing something to the appropriate registers. */
      data->resume = 1;

      return (result);

 err_freqfree:
      kfree(data->freq_table);
 err_unreg:
      acpi_processor_unregister_performance(&data->acpi_data, cpu);
 err_free:
      kfree(data);
      acpi_io_data[cpu] = NULL;

      return (result);
}


static int
acpi_cpufreq_cpu_exit (
      struct cpufreq_policy   *policy)
{
      struct cpufreq_acpi_io *data = acpi_io_data[policy->cpu];

      dprintk("acpi_cpufreq_cpu_exit\n");

      if (data) {
            cpufreq_frequency_table_put_attr(policy->cpu);
            acpi_io_data[policy->cpu] = NULL;
            acpi_processor_unregister_performance(&data->acpi_data,
                                                  policy->cpu);
            kfree(data);
      }

      return (0);
}


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


static struct cpufreq_driver acpi_cpufreq_driver = {
      .verify     = acpi_cpufreq_verify,
      .target     = acpi_cpufreq_target,
      .get        = acpi_cpufreq_get,
      .init       = acpi_cpufreq_cpu_init,
      .exit       = acpi_cpufreq_cpu_exit,
      .name       = "acpi-cpufreq",
      .owner            = THIS_MODULE,
      .attr           = acpi_cpufreq_attr,
};


static int __init
acpi_cpufreq_init (void)
{
      dprintk("acpi_cpufreq_init\n");

      return cpufreq_register_driver(&acpi_cpufreq_driver);
}


static void __exit
acpi_cpufreq_exit (void)
{
      dprintk("acpi_cpufreq_exit\n");

      cpufreq_unregister_driver(&acpi_cpufreq_driver);
      return;
}


late_initcall(acpi_cpufreq_init);
module_exit(acpi_cpufreq_exit);


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