/* SPDX-License-Identifier: GPL-2.0-only */
#ifndef _WINDFARM_PID_H
#define _WINDFARM_PID_H

/*
 * Windfarm PowerMac thermal control. Generic PID helpers
 *
 * (c) Copyright 2005 Benjamin Herrenschmidt, IBM Corp.
 *                    <benh@kernel.crashing.org>
 *
 * This is a pair of generic PID helpers that can be used by
 * control loops. One is the basic PID implementation, the
 * other one is more specifically tailored to the loops used
 * for CPU control with 2 input sample types (temp and power)
 */

/*
 * *** Simple PID ***
 */

#define WF_PID_MAX_HISTORY      32

/* This parameter array is passed to the PID algorithm. Currently,
 * we don't support changing parameters on the fly as it's not needed
 * but could be implemented (with necessary adjustment of the history
 * buffer
 */
struct wf_pid_param {
        int     interval;       /* Interval between samples in seconds */
        int     history_len;    /* Size of history buffer */
        int     additive;       /* 1: target relative to previous value */
        s32     gd, gp, gr;     /* PID gains */
        s32     itarget;        /* PID input target */
        s32     min,max;        /* min and max target values */
};

struct wf_pid_state {
        int     first;                          /* first run of the loop */
        int     index;                          /* index of current sample */
        s32     target;                         /* current target value */
        s32     samples[WF_PID_MAX_HISTORY];    /* samples history buffer */
        s32     errors[WF_PID_MAX_HISTORY];     /* error history buffer */

        struct wf_pid_param param;
};

extern void wf_pid_init(struct wf_pid_state *st, struct wf_pid_param *param);
extern s32 wf_pid_run(struct wf_pid_state *st, s32 sample);


/*
 * *** CPU PID ***
 */

#define WF_CPU_PID_MAX_HISTORY  32

/* This parameter array is passed to the CPU PID algorithm. Currently,
 * we don't support changing parameters on the fly as it's not needed
 * but could be implemented (with necessary adjustment of the history
 * buffer
 */
struct wf_cpu_pid_param {
        int     interval;       /* Interval between samples in seconds */
        int     history_len;    /* Size of history buffer */
        s32     gd, gp, gr;     /* PID gains */
        s32     pmaxadj;        /* PID max power adjust */
        s32     ttarget;        /* PID input target */
        s32     tmax;           /* PID input max */
        s32     min,max;        /* min and max target values */
};

struct wf_cpu_pid_state {
        int     first;                          /* first run of the loop */
        int     index;                          /* index of current power */
        int     tindex;                         /* index of current temp */
        s32     target;                         /* current target value */
        s32     last_delta;                     /* last Tactual - Ttarget */
        s32     powers[WF_PID_MAX_HISTORY];     /* power history buffer */
        s32     errors[WF_PID_MAX_HISTORY];     /* error history buffer */
        s32     temps[2];                       /* temp. history buffer */

        struct wf_cpu_pid_param param;
};

extern void wf_cpu_pid_init(struct wf_cpu_pid_state *st,
                            struct wf_cpu_pid_param *param);
extern s32 wf_cpu_pid_run(struct wf_cpu_pid_state *st, s32 power, s32 temp);

#endif /* _WINDFARM_PID_H */