/*-
 * Copyright (c) 2004 Colin Percival
 * Copyright (c) 2005 Nate Lawson
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted providing 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 <err.h>
#include <fcntl.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>

#ifdef __i386__
#include <machine/apm_bios.h>
#endif

#include <sys/ioctl.h>
#include <sys/sysctl.h>
#include <sys/resource.h>

#define DEFAULT_ACTIVE_PERCENT	80
#define DEFAULT_IDLE_PERCENT	90
#define DEFAULT_POLL_INTERVAL	500

enum modes_t {
	MODE_MIN,
	MODE_ADAPTIVE,
	MODE_MAX,
};

enum power_src_t {
	SRC_AC,
	SRC_BATTERY,
	SRC_UNKNOWN,
};

const char *modes[] = {
	"AC",
	"battery",
	"unknown"
};

#define ACPIAC		"hw.acpi.acline"
#define APMDEV		"/dev/apm"

static int	read_usage_times(long *idle, long *total);
static int	read_freqs(int *numfreqs, int **freqs);
static int	set_freq(int freq);
static void	acline_init(void);
static int	acline_read(void);
static void	parse_mode(char *arg, int *mode, int ch);
static void	usage(void);

/* Sysctl data structures. */
static int	cp_time_mib[2];
static int	freq_mib[4];
static int	levels_mib[4];
static int	acline_mib[3];

/* Configuration */
static int	cpu_running_mark;
static int	cpu_idle_mark;
static int	poll_ival;

static int	apm_fd;

static int
read_usage_times(long *idle, long *total)
{
	static long idle_old, total_old;
	long cp_time[CPUSTATES], i, total_new;
	size_t cp_time_len;
	int error;

	cp_time_len = sizeof(cp_time);
	error = sysctl(cp_time_mib, 2, cp_time, &cp_time_len, NULL, 0);
	if (error)
		return (error);
	for (total_new = 0, i = 0; i < CPUSTATES; i++)
		total_new += cp_time[i];

	if (idle)
		*idle = cp_time[CP_IDLE] - idle_old;
	if (total)
		*total = total_new - total_old;

	idle_old = cp_time[CP_IDLE];
	total_old = total_new;

	return (0);
}

static int
read_freqs(int *numfreqs, int **freqs)
{
	char *freqstr, *p, *q;
	int i;
	size_t len = 0;

	if (sysctl(levels_mib, 4, NULL, &len, NULL, 0))
		return (-1);
	if ((freqstr = malloc(len)) == NULL)
		return (-1);
	if (sysctl(levels_mib, 4, freqstr, &len, NULL, 0))
		return (-1);

	*numfreqs = 1;
	for (p = freqstr; *p != '\0'; p++)
		if (*p == ' ')
			(*numfreqs)++;

	if ((*freqs = malloc(*numfreqs * sizeof(int))) == NULL) {
		free(freqstr);
		return (-1);
	}
	for (i = 0, p = freqstr; i < *numfreqs; i++) {
		q = strchr(p, ' ');
		if (q != NULL)
			*q = '\0';
		if (sscanf(p, "%d/%*d", &(*freqs)[i]) != 1) {
			free(freqstr);
			free(*freqs);
			return (-1);
		}
		p = q + 1;
	}

	free(freqstr);
	return (0);
}

static int
set_freq(int freq)
{

	if (sysctl(freq_mib, 4, NULL, NULL, &freq, sizeof(freq)))
		return (-1);

	return (0);
}

/*
 * Try to use ACPI to find the AC line status.  If this fails, fall back
 * to APM.  If nothing succeeds, we'll just run in default mode.
 */
static void
acline_init()
{
	int acline;
	size_t len;

	apm_fd = -1;
	len = sizeof(acline);
	if (sysctlbyname(ACPIAC, &acline, &len, NULL, 0) == 0) {
		len = 3;
		if (sysctlnametomib(ACPIAC, acline_mib, &len))
			err(1, "lookup acline");
	} else {
		apm_fd = open(APMDEV, O_RDONLY);
		if (apm_fd == -1)
			warnx(
		"cannot read AC line status, using default settings");
	}
}

static int
acline_read()
{
	int acline = SRC_UNKNOWN;
	size_t len;

#ifdef __i386__
	struct apm_info info;

	if (apm_fd != -1 && ioctl(apm_fd, APMIO_GETINFO, &info) == 0)
		acline = info.ai_acline ? SRC_AC : SRC_BATTERY;
#endif

	if (acline == SRC_UNKNOWN) {
		len = sizeof(acline);
		if (sysctl(acline_mib, 3, &acline, &len, NULL, 0) == 0)
			acline = acline ? SRC_AC : SRC_BATTERY;
	}

	return (acline);
}

static void
parse_mode(char *arg, int *mode, int ch)
{

	if (strcmp(arg, "min") == 0)
		*mode = MODE_MIN;
	else if (strcmp(arg, "max") == 0)
		*mode = MODE_MAX;
	else if (strcmp(arg, "adaptive") == 0)
		*mode = MODE_ADAPTIVE;
	else
		errx(1, "bad option: -%c %s", (char)ch, optarg);
}

static void
usage(void)
{

	fprintf(stderr,
"usage: powerd [-v] [-a mode] [-b mode] [-i %%] [-n mode] [-p ival] [-r %%]\n");
	exit(1);
}

int
main(int argc, char * argv[])
{
	long idle, total;
	int curfreq, *freqs, i, numfreqs;
	int ch, mode_ac, mode_battery, mode_none, acline, mode, vflag;
	size_t len;

	/* Default mode for all AC states is adaptive. */
	mode_ac = mode_battery = mode_none = MODE_ADAPTIVE;
	cpu_running_mark = DEFAULT_ACTIVE_PERCENT;
	cpu_idle_mark = DEFAULT_IDLE_PERCENT;
	poll_ival = DEFAULT_POLL_INTERVAL;
	vflag = 0;
	apm_fd = -1;

	while ((ch = getopt(argc, argv, "a:b:i:n:p:r:v")) != EOF)
		switch (ch) {
		case 'a':
			parse_mode(optarg, &mode_ac, ch);
			break;
		case 'b':
			parse_mode(optarg, &mode_battery, ch);
			break;
		case 'i':
			cpu_idle_mark = atoi(optarg);
			if (cpu_idle_mark < 0 || cpu_idle_mark > 100) {
				warnx("%d is not a valid percent",
				    cpu_idle_mark);
				usage();
			}
			break;
		case 'n':
			parse_mode(optarg, &mode_none, ch);
			break;
		case 'p':
			poll_ival = atoi(optarg);
			if (poll_ival < 5) {
				warnx("poll interval is in units of ms");
				usage();
			}
			break;
		case 'r':
			cpu_running_mark = atoi(optarg);
			if (cpu_running_mark < 0 || cpu_running_mark > 100) {
				warnx("%d is not a valid percent",
				    cpu_running_mark);
				usage();
			}
			break;
		case 'v':
			vflag = 1;
			break;
		default:
			usage();
		}

	/* Poll interval is in units of ms. */
	poll_ival *= 1000;

	/* Look up various sysctl MIBs. */
	len = 2;
	if (sysctlnametomib("kern.cp_time", cp_time_mib, &len))
		err(1, "lookup kern.cp_time");
	len = 4;
	if (sysctlnametomib("dev.cpu.0.freq", freq_mib, &len))
		err(1, "lookup freq");
	len = 4;
	if (sysctlnametomib("dev.cpu.0.freq_levels", levels_mib, &len))
		err(1, "lookup freq_levels");

	/* Check if we can read the idle time and supported freqs. */
	if (read_usage_times(NULL, NULL))
		err(1, "read_usage_times");
	if (read_freqs(&numfreqs, &freqs))
		err(1, "error reading supported CPU frequencies");

	/* Decide whether to use ACPI or APM to read the AC line status. */
	acline_init();

	/* Run in the background unless in verbose mode. */
	if (!vflag)
		daemon(0, 0);

	/* Main loop. */
	for (;;) {
		/* Check status every few milliseconds. */
		usleep(poll_ival);

		/* Read the current AC status and record the mode. */
		acline = acline_read();
		switch (acline) {
		case SRC_AC:
			mode = mode_ac;
			break;
		case SRC_BATTERY:
			mode = mode_battery;
			break;
		case SRC_UNKNOWN:
			mode = mode_none;
			break;
		default:
			errx(1, "invalid AC line status %d", acline);
		}

		/* Read the current frequency. */
		len = sizeof(curfreq);
		if (sysctl(freq_mib, 4, &curfreq, &len, NULL, 0))
			err(1, "error reading current CPU frequency");

		/* Always switch to the lowest frequency in min mode. */
		if (mode == MODE_MIN) {
			if (curfreq != freqs[numfreqs - 1]) {
				if (vflag) {
					printf("now operating on %s power; "
					    "changing frequency to %d MHz\n",
					    modes[acline], freqs[numfreqs - 1]);
				}
				if (set_freq(freqs[numfreqs - 1]))
					err(1, "error setting CPU freq %d",
					    freqs[numfreqs - 1]);
			}
			continue;
		}

		/* Always switch to the highest frequency in max mode. */
		if (mode == MODE_MAX) {
			if (curfreq != freqs[0]) {
				if (vflag) {
					printf("now operating on %s power; "
					    "changing frequency to %d MHz\n",
					    modes[acline], freqs[0]);
				}
				if (set_freq(freqs[0]))
					err(1, "error setting CPU freq %d",
					    freqs[0]);
			}
			continue;
		}

		/* Adaptive mode; get the current CPU usage times. */
		if (read_usage_times(&idle, &total))
			err(1, "read_usage_times");

		/*
		 * If we're idle less than the active mark, jump the CPU to
		 * its fastest speed if we're not there yet.  If we're idle
		 * more than the idle mark, drop down to the first setting
		 * that is half the current speed (exponential backoff).
		 */
		if (idle < (total * cpu_running_mark) / 100 &&
		    curfreq < freqs[0]) {
			if (vflag) {
				printf("idle time < %d%%, increasing clock"
				    " speed from %d MHz to %d MHz\n",
				    cpu_running_mark, curfreq, freqs[0]);
			}
			if (set_freq(freqs[0]))
				err(1, "error setting CPU frequency %d",
				    freqs[0]);
		} else if (idle > (total * cpu_idle_mark) / 100 &&
		    curfreq > freqs[numfreqs - 1]) {
			for (i = 0; i < numfreqs - 1; i++) {
				if (freqs[i] <= curfreq / 2)
					break;
			}
			if (vflag) {
				printf("idle time > %d%%, decreasing clock"
				    " speed from %d MHz to %d MHz\n",
				    cpu_idle_mark, curfreq, freqs[i]);
			}
			if (set_freq(freqs[i]))
				err(1, "error setting CPU frequency %d",
				    freqs[i]);
		}
	}
	/* NOTREACHED */

	exit(0);
}