linux-imx

/*

 * POWERNV cpufreq driver for the IBM POWER processors

 *

 * (C) Copyright IBM 2014

 *

 * Author: Vaidyanathan Srinivasan <svaidy at linux.vnet.ibm.com>

 *

 * 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.

 *

 */

​

#define pr_fmt(fmt) "powernv-cpufreq: " fmt

​

#include <linux/kernel.h>

#include <linux/sysfs.h>

#include <linux/cpumask.h>

#include <linux/module.h>

#include <linux/cpufreq.h>

#include <linux/smp.h>

#include <linux/of.h>

#include <linux/reboot.h>

#include <linux/slab.h>

#include <linux/cpu.h>

#include <linux/hashtable.h>

#include <trace/events/power.h>

​

#include <asm/cputhreads.h>

#include <asm/firmware.h>

#include <asm/reg.h>

#include <asm/smp.h> /* Required for cpu_sibling_mask() in UP configs */

#include <asm/opal.h>

#include <linux/timer.h>

​

#define POWERNV_MAX_PSTATES_ORDER  8

#define POWERNV_MAX_PSTATES (1UL << (POWERNV_MAX_PSTATES_ORDER))

#define PMSR_PSAFE_ENABLE   (1UL << 30)

#define PMSR_SPR_EM_DISABLE (1UL << 31)

#define MAX_PSTATE_SHIFT    32

#define LPSTATE_SHIFT       48

#define GPSTATE_SHIFT       56

​

#define MAX_RAMP_DOWN_TIME              5120

/*

 * On an idle system we want the global pstate to ramp-down from max value to

 * min over a span of ~5 secs. Also we want it to initially ramp-down slowly and

 * then ramp-down rapidly later on.

 *

 * This gives a percentage rampdown for time elapsed in milliseconds.

 * ramp_down_percentage = ((ms * ms) >> 18)

 *          ~= 3.8 * (sec * sec)

 *

 * At 0 ms  ramp_down_percent = 0

 * At 5120 ms   ramp_down_percent = 100

 */

#define ramp_down_percent(time)     ((time * time) >> 18)

​

/* Interval after which the timer is queued to bring down global pstate */

#define GPSTATE_TIMER_INTERVAL              2000

​

/**

 * struct global_pstate_info -  Per policy data structure to maintain history of

 *              global pstates

 * @highest_lpstate_idx:    The local pstate index from which we are

 *              ramping down

 * @elapsed_time:       Time in ms spent in ramping down from

 *              highest_lpstate_idx

 * @last_sampled_time:      Time from boot in ms when global pstates were

 *              last set

 * @last_lpstate_idx,       Last set value of local pstate and global

 * last_gpstate_idx     pstate in terms of cpufreq table index

 * @timer:          Is used for ramping down if cpu goes idle for

 *              a long time with global pstate held high

 * @gpstate_lock:       A spinlock to maintain synchronization between

 *              routines called by the timer handler and

 *              governer's target_index calls

 */

struct global_pstate_info {

    int highest_lpstate_idx;

    unsigned int elapsed_time;

    unsigned int last_sampled_time;

    int last_lpstate_idx;

    int last_gpstate_idx;

    spinlock_t gpstate_lock;

    struct timer_list timer;