/*
   *  (C) 2010,2011       Thomas Renninger <trenn@suse.de>, Novell Inc.
   *
   *  Licensed under the terms of the GNU GPL License version 2.
   */
  
  #if defined(__i386__) || defined(__x86_64__)
  
  #include <stdio.h>
  #include <stdint.h>
  #include <stdlib.h>
  #include <string.h>
  #include <limits.h>
  
  #include <cpufreq.h>
  
  #include "helpers/helpers.h"
  #include "idle_monitor/cpupower-monitor.h"
  
  #define MSR_APERF	0xE8
  #define MSR_MPERF	0xE7
  
  #define MSR_TSC	0x10

  #define MSR_AMD_HWCR 0xc0010015

  enum mperf_id { C0 = 0, Cx, AVG_FREQ, MPERF_CSTATE_COUNT };
  
  static int mperf_get_count_percent(unsigned int self_id, double *percent,
  				   unsigned int cpu);
  static int mperf_get_count_freq(unsigned int id, unsigned long long *count,
  				unsigned int cpu);

  static struct timespec time_start, time_end;

  
  static cstate_t mperf_cstates[MPERF_CSTATE_COUNT] = {
  	{
  		.name			= "C0",
  		.desc			= N_("Processor Core not idle"),
  		.id			= C0,
  		.range			= RANGE_THREAD,
  		.get_count_percent	= mperf_get_count_percent,
  	},
  	{
  		.name			= "Cx",
  		.desc			= N_("Processor Core in an idle state"),
  		.id			= Cx,
  		.range			= RANGE_THREAD,
  		.get_count_percent	= mperf_get_count_percent,
  	},
  
  	{
  		.name			= "Freq",
  		.desc			= N_("Average Frequency (including boost) in MHz"),
  		.id			= AVG_FREQ,
  		.range			= RANGE_THREAD,
  		.get_count		= mperf_get_count_freq,
  	},
  };

  enum MAX_FREQ_MODE { MAX_FREQ_SYSFS, MAX_FREQ_TSC_REF };
  static int max_freq_mode;
  /*
   * The max frequency mperf is ticking at (in C0), either retrieved via:
   *   1) calculated after measurements if we know TSC ticks at mperf/P0 frequency
   *   2) cpufreq /sys/devices/.../cpu0/cpufreq/cpuinfo_max_freq at init time
   * 1. Is preferred as it also works without cpufreq subsystem (e.g. on Xen)
   */
  static unsigned long max_frequency;

  static unsigned long long tsc_at_measure_start;
  static unsigned long long tsc_at_measure_end;

  static unsigned long long *mperf_previous_count;
  static unsigned long long *aperf_previous_count;
  static unsigned long long *mperf_current_count;
  static unsigned long long *aperf_current_count;

  /* valid flag for all CPUs. If a MSR read failed it will be zero */
  static int *is_valid;
  
  static int mperf_get_tsc(unsigned long long *tsc)
  {

  	int ret;
  	ret = read_msr(0, MSR_TSC, tsc);
  	if (ret)
  		dprint("Reading TSC MSR failed, returning %llu
  ", *tsc);
  	return ret;

  }
  
  static int mperf_init_stats(unsigned int cpu)
  {
  	unsigned long long val;
  	int ret;
  
  	ret = read_msr(cpu, MSR_APERF, &val);
  	aperf_previous_count[cpu] = val;
  	ret |= read_msr(cpu, MSR_MPERF, &val);
  	mperf_previous_count[cpu] = val;
  	is_valid[cpu] = !ret;

  	return 0;
  }
  
  static int mperf_measure_stats(unsigned int cpu)
  {
  	unsigned long long val;
  	int ret;
  
  	ret = read_msr(cpu, MSR_APERF, &val);
  	aperf_current_count[cpu] = val;
  	ret |= read_msr(cpu, MSR_MPERF, &val);
  	mperf_current_count[cpu] = val;
  	is_valid[cpu] = !ret;

  	return 0;
  }

  static int mperf_get_count_percent(unsigned int id, double *percent,
  				   unsigned int cpu)
  {
  	unsigned long long aperf_diff, mperf_diff, tsc_diff;

  	unsigned long long timediff;

  
  	if (!is_valid[cpu])
  		return -1;
  
  	if (id != C0 && id != Cx)
  		return -1;
  
  	mperf_diff = mperf_current_count[cpu] - mperf_previous_count[cpu];
  	aperf_diff = aperf_current_count[cpu] - aperf_previous_count[cpu];

  	if (max_freq_mode == MAX_FREQ_TSC_REF) {
  		tsc_diff = tsc_at_measure_end - tsc_at_measure_start;
  		*percent = 100.0 * mperf_diff / tsc_diff;
  		dprint("%s: TSC Ref - mperf_diff: %llu, tsc_diff: %llu
  ",
  		       mperf_cstates[id].name, mperf_diff, tsc_diff);
  	} else if (max_freq_mode == MAX_FREQ_SYSFS) {
  		timediff = timespec_diff_us(time_start, time_end);
  		*percent = 100.0 * mperf_diff / timediff;
  		dprint("%s: MAXFREQ - mperf_diff: %llu, time_diff: %llu
  ",
  		       mperf_cstates[id].name, mperf_diff, timediff);
  	} else
  		return -1;

  
  	if (id == Cx)
  		*percent = 100.0 - *percent;

  	dprint("%s: previous: %llu - current: %llu - (%u)
  ",
  		mperf_cstates[id].name, mperf_diff, aperf_diff, cpu);

  	dprint("%s: %f
  ", mperf_cstates[id].name, *percent);
  	return 0;
  }
  
  static int mperf_get_count_freq(unsigned int id, unsigned long long *count,

  				unsigned int cpu)

  {

  	unsigned long long aperf_diff, mperf_diff, time_diff, tsc_diff;

  
  	if (id != AVG_FREQ)
  		return 1;
  
  	if (!is_valid[cpu])
  		return -1;
  
  	mperf_diff = mperf_current_count[cpu] - mperf_previous_count[cpu];
  	aperf_diff = aperf_current_count[cpu] - aperf_previous_count[cpu];

  	if (max_freq_mode == MAX_FREQ_TSC_REF) {
  		/* Calculate max_freq from TSC count */
  		tsc_diff = tsc_at_measure_end - tsc_at_measure_start;
  		time_diff = timespec_diff_us(time_start, time_end);
  		max_frequency = tsc_diff / time_diff;
  	}

  	*count = max_frequency * ((double)aperf_diff / mperf_diff);
  	dprint("%s: Average freq based on %s maximum frequency:
  ",
  	       mperf_cstates[id].name,
  	       (max_freq_mode == MAX_FREQ_TSC_REF) ? "TSC calculated" : "sysfs read");
  	dprint("%max_frequency: %lu", max_frequency);
  	dprint("aperf_diff: %llu
  ", aperf_diff);
  	dprint("mperf_diff: %llu
  ", mperf_diff);
  	dprint("avg freq:   %llu
  ", *count);

  	return 0;
  }
  
  static int mperf_start(void)
  {
  	int cpu;
  	unsigned long long dbg;

  	clock_gettime(CLOCK_REALTIME, &time_start);

  	mperf_get_tsc(&tsc_at_measure_start);
  
  	for (cpu = 0; cpu < cpu_count; cpu++)
  		mperf_init_stats(cpu);
  
  	mperf_get_tsc(&dbg);
  	dprint("TSC diff: %llu
  ", dbg - tsc_at_measure_start);
  	return 0;
  }
  
  static int mperf_stop(void)
  {
  	unsigned long long dbg;
  	int cpu;

  	for (cpu = 0; cpu < cpu_count; cpu++)
  		mperf_measure_stats(cpu);

  	mperf_get_tsc(&tsc_at_measure_end);
  	clock_gettime(CLOCK_REALTIME, &time_end);

  	mperf_get_tsc(&dbg);
  	dprint("TSC diff: %llu
  ", dbg - tsc_at_measure_end);
  
  	return 0;
  }

  /*
   * Mperf register is defined to tick at P0 (maximum) frequency
   *
   * Instead of reading out P0 which can be tricky to read out from HW,
   * we use TSC counter if it reliably ticks at P0/mperf frequency.
   *
   * Still try to fall back to:
   * /sys/devices/system/cpu/cpu0/cpufreq/cpuinfo_max_freq
   * on older Intel HW without invariant TSC feature.
   * Or on AMD machines where TSC does not tick at P0 (do not exist yet, but
   * it's still double checked (MSR_AMD_HWCR)).
   *
   * On these machines the user would still get useful mperf
   * stats when acpi-cpufreq driver is loaded.
   */
  static int init_maxfreq_mode(void)

  {

  	int ret;
  	unsigned long long hwcr;

  	unsigned long min;

  	if (!cpupower_cpu_info.caps & CPUPOWER_CAP_INV_TSC)
  		goto use_sysfs;
  
  	if (cpupower_cpu_info.vendor == X86_VENDOR_AMD) {
  		/* MSR_AMD_HWCR tells us whether TSC runs at P0/mperf
  		 * freq.
  		 * A test whether hwcr is accessable/available would be:
  		 * (cpupower_cpu_info.family > 0x10 ||
  		 *   cpupower_cpu_info.family == 0x10 &&
  		 *   cpupower_cpu_info.model >= 0x2))
  		 * This should be the case for all aperf/mperf
  		 * capable AMD machines and is therefore safe to test here.
  		 * Compare with Linus kernel git commit: acf01734b1747b1ec4
  		 */
  		ret = read_msr(0, MSR_AMD_HWCR, &hwcr);
  		/*
  		 * If the MSR read failed, assume a Xen system that did
  		 * not explicitly provide access to it and assume TSC works
  		*/
  		if (ret != 0) {
  			dprint("TSC read 0x%x failed - assume TSC working
  ",
  			       MSR_AMD_HWCR);
  			return 0;
  		} else if (1 & (hwcr >> 24)) {
  			max_freq_mode = MAX_FREQ_TSC_REF;
  			return 0;
  		} else { /* Use sysfs max frequency if available */ }
  	} else if (cpupower_cpu_info.vendor == X86_VENDOR_INTEL) {
  		/*
  		 * On Intel we assume mperf (in C0) is ticking at same
  		 * rate than TSC
  		 */
  		max_freq_mode = MAX_FREQ_TSC_REF;
  		return 0;
  	}
  use_sysfs:

  	if (cpufreq_get_hardware_limits(0, &min, &max_frequency)) {
  		dprint("Cannot retrieve max freq from cpufreq kernel "
  		       "subsystem
  ");

  		return -1;

  	}

  	max_freq_mode = MAX_FREQ_SYSFS;
  	return 0;
  }
  
  /*
   * This monitor provides:
   *
   * 1) Average frequency a CPU resided in
   *    This always works if the CPU has aperf/mperf capabilities
   *
   * 2) C0 and Cx (any sleep state) time a CPU resided in
   *    Works if mperf timer stops ticking in sleep states which
   *    seem to be the case on all current HW.
   * Both is directly retrieved from HW registers and is independent
   * from kernel statistics.
   */
  struct cpuidle_monitor mperf_monitor;
  struct cpuidle_monitor *mperf_register(void)
  {
  	if (!(cpupower_cpu_info.caps & CPUPOWER_CAP_APERF))
  		return NULL;
  
  	if (init_maxfreq_mode())
  		return NULL;

  
  	/* Free this at program termination */

  	is_valid = calloc(cpu_count, sizeof(int));
  	mperf_previous_count = calloc(cpu_count, sizeof(unsigned long long));
  	aperf_previous_count = calloc(cpu_count, sizeof(unsigned long long));
  	mperf_current_count = calloc(cpu_count, sizeof(unsigned long long));
  	aperf_current_count = calloc(cpu_count, sizeof(unsigned long long));

  	mperf_monitor.name_len = strlen(mperf_monitor.name);
  	return &mperf_monitor;
  }

  void mperf_unregister(void)
  {

  	free(mperf_previous_count);
  	free(aperf_previous_count);
  	free(mperf_current_count);
  	free(aperf_current_count);
  	free(is_valid);
  }
  
  struct cpuidle_monitor mperf_monitor = {
  	.name			= "Mperf",
  	.hw_states_num		= MPERF_CSTATE_COUNT,
  	.hw_states		= mperf_cstates,
  	.start			= mperf_start,
  	.stop			= mperf_stop,
  	.do_register		= mperf_register,
  	.unregister		= mperf_unregister,
  	.needs_root		= 1,
  	.overflow_s		= 922000000 /* 922337203 seconds TSC overflow
  					       at 20GHz */
  };
  #endif /* #if defined(__i386__) || defined(__x86_64__) */