fan: Re-add interpolation-based algorithm

Signed-off-by: Tim Crawford <tcrawford@system76.com>

Author: crawfxrd

src/app/main/Makefile.mk

@@ -5,7 +5,6 @@ app-y += battery.c
 app-y += config.c
 app-y += ecpm.c
 app-$(CONFIG_BUS_ESPI) += espi.c
-app-y += fan.c
 app-y += gctrl.c
 app-y += kbc.c
 app-y += kbscan.c
@@ -63,21 +62,7 @@ endif
 endif
 
 # Fan configs
-ifneq ($(CONFIG_FAN1_PWM),)
-CFLAGS += -DFAN1_PWM=$(CONFIG_FAN1_PWM)
-ifneq ($(CONFIG_FAN1_PWM_MIN),)
-CFLAGS += -DFAN1_PWM_MIN=$(CONFIG_FAN1_PWM_MIN)
-endif
-CFLAGS += -DBOARD_FAN1_POINTS=$(CONFIG_FAN1_POINTS)
-endif
-
-ifneq ($(CONFIG_FAN2_PWM),)
-CFLAGS += -DFAN2_PWM=$(CONFIG_FAN2_PWM)
-ifneq ($(CONFIG_FAN2_PWM_MIN),)
-CFLAGS += -DFAN2_PWM_MIN=$(CONFIG_FAN2_PWM_MIN)
-endif
-CFLAGS += -DBOARD_FAN2_POINTS=$(CONFIG_FAN2_POINTS)
-endif
+include $(APP_DIR)/fan/Makefile.mk
 
 # Set battery charging thresholds
 BATTERY_START_THRESHOLD?=90

src/app/main/fan/Makefile.mk

@@ -0,0 +1,30 @@
+# SPDX-License-Identifier: GPL-3.0-only
+
+ifneq ($(CONFIG_FAN1_PWM),)
+CFLAGS += -DFAN1_PWM=$(CONFIG_FAN1_PWM)
+ifneq ($(CONFIG_FAN1_PWM_MIN),)
+CFLAGS += -DFAN1_PWM_MIN=$(CONFIG_FAN1_PWM_MIN)
+endif
+CFLAGS += -DBOARD_FAN1_POINTS=$(CONFIG_FAN1_POINTS)
+endif
+
+ifneq ($(CONFIG_FAN2_PWM),)
+CFLAGS += -DFAN2_PWM=$(CONFIG_FAN2_PWM)
+ifneq ($(CONFIG_FAN2_PWM_MIN),)
+CFLAGS += -DFAN2_PWM_MIN=$(CONFIG_FAN2_PWM_MIN)
+endif
+CFLAGS += -DBOARD_FAN2_POINTS=$(CONFIG_FAN2_POINTS)
+endif
+
+#CONFIG_FAN_CTRL_INTERP = y
+CONFIG_FAN_CTRL_STEP = y
+
+ifeq ($(CONFIG_FAN_CTRL_INTERP),y)
+CFLAGS += -DCONFIG_FAN_CTRL_INTERP=1
+app-y += fan/interp.c
+else ifeq ($(CONFIG_FAN_CTRL_STEP),y)
+CFLAGS += -DCONFIG_FAN_CTRL_STEP=1
+app-y += fan/step.c
+endif
+
+app-y += fan/common.c

src/app/main/fan/common.c

@@ -0,0 +1,47 @@
+// SPDX-License-Identifier: GPL-3.0-only
+
+#include <app/fan.h>
+#include <ec/pwm.h>
+
+bool fan_max = false;
+static enum FanMode fan_mode = FAN_MODE_AUTO;
+
+#define TACH_FREQ (CONFIG_CLOCK_FREQ_KHZ * 1000UL)
+
+// Fan Speed (RPM) = 60 / (1/fs sec * {FnTMRR, FnRLRR} * P)
+// - n: 1 or 2
+// - P: the numbers of square pulses per revolution
+// - fs: sample rate (FreqEC / 128)
+// - {FnTMRR, FnTLRR} = 0000h: Fan Speed is zero
+#define TACH_TO_RPM(x) (60UL * TACH_FREQ / 128UL / 2UL / (x))
+
+uint16_t fan_get_tach0_rpm(void) {
+    uint16_t rpm = (F1TMRR << 8) | F1TLRR;
+
+    if (rpm)
+        rpm = TACH_TO_RPM(rpm);
+
+    return rpm;
+}
+
+uint16_t fan_get_tach1_rpm(void) {
+    uint16_t rpm = (F2TMRR << 8) | F2TLRR;
+
+    if (rpm)
+        rpm = TACH_TO_RPM(rpm);
+
+    return rpm;
+}
+
+void fan_reset(void) {
+    // Do not manually set fans to maximum speed
+    fan_max = false;
+}
+
+enum FanMode fan_get_mode(void) {
+    return fan_mode;
+}
+
+void fan_set_mode(enum FanMode mode) {
+    fan_mode = mode;
+}

src/app/main/fan/interp.c

@@ -0,0 +1,258 @@
+// SPDX-License-Identifier: GPL-3.0-only
+
+#include <app/fan.h>
+#include <app/power.h>
+#include <common/debug.h>
+#include <common/macro.h>
+#include <ec/pwm.h>
+#include <drivers/dgpu/dgpu.h>
+
+#if CONFIG_PLATFORM_INTEL
+#include <app/peci.h>
+#endif
+
+
+static uint8_t last_fan1_duty = 0;
+static uint8_t last_fan2_duty = 0;
+
+uint8_t fan1_pwm_actual = 0;
+uint8_t fan1_pwm_target = 0;
+uint16_t fan1_rpm = 0;
+
+uint8_t fan2_pwm_actual = 0;
+uint8_t fan2_pwm_target = 0;
+uint16_t fan2_rpm = 0;
+
+#define MAX_FAN_SPEED CTR0
+#define MIN_FAN_SPEED 0
+
+#ifndef SMOOTH_FANS_UP
+#define SMOOTH_FANS_UP 45 // default to ~11 seconds for full ramp-up
+#endif
+#ifndef SMOOTH_FANS_DOWN
+#define SMOOTH_FANS_DOWN 100 // default to ~25 seconds for full ramp-down
+#endif
+
+#ifndef SMOOTH_FANS_MIN
+#define SMOOTH_FANS_MIN 0 // default to smoothing all fan speed changes
+#endif
+
+#define MAX_JUMP_UP ((MAX_FAN_SPEED - MIN_FAN_SPEED) / (uint8_t)SMOOTH_FANS_UP)
+#define MAX_JUMP_DOWN ((MAX_FAN_SPEED - MIN_FAN_SPEED) / (uint8_t)SMOOTH_FANS_DOWN)
+
+#define MIN_SPEED_TO_SMOOTH PWM_DUTY(SMOOTH_FANS_MIN)
+
+// Fan speed is the lowest requested over HEATUP seconds
+#ifndef BOARD_FAN1_HEATUP
+#define BOARD_FAN1_HEATUP 4
+#endif
+
+static uint8_t FAN1_HEATUP[BOARD_FAN1_HEATUP] = { 0 };
+
+// Fan speed is the highest HEATUP speed over COOLDOWN seconds
+#ifndef BOARD_FAN1_COOLDOWN
+#define BOARD_FAN1_COOLDOWN 10
+#endif
+
+static uint8_t FAN1_COOLDOWN[BOARD_FAN1_COOLDOWN] = { 0 };
+
+// Fan curve with temperature in degrees C, duty cycle in percent
+static const struct FanPoint __code FAN1_POINTS[] = {
+#ifndef BOARD_FAN1_POINTS
+#error Board must declare fan points
+#else
+    BOARD_FAN1_POINTS
+#endif
+};
+
+static const struct Fan __code FAN1 = {
+    .points = FAN1_POINTS,
+    .points_size = ARRAY_SIZE(FAN1_POINTS),
+    .heatup = FAN1_HEATUP,
+    .heatup_size = ARRAY_SIZE(FAN1_HEATUP),
+    .cooldown = FAN1_COOLDOWN,
+    .cooldown_size = ARRAY_SIZE(FAN1_COOLDOWN),
+};
+
+#ifdef FAN2_PWM
+
+// Fan speed is the lowest requested over HEATUP seconds
+#ifndef BOARD_FAN2_HEATUP
+#define BOARD_FAN2_HEATUP 4
+#endif
+
+static uint8_t FAN2_HEATUP[BOARD_FAN2_HEATUP] = { 0 };
+
+// Fan speed is the highest HEATUP speed over COOLDOWN seconds
+#ifndef BOARD_FAN2_COOLDOWN
+#define BOARD_FAN2_COOLDOWN 10
+#endif
+
+static uint8_t FAN2_COOLDOWN[BOARD_FAN2_COOLDOWN] = { 0 };
+
+// Fan curve with temperature in degrees C, duty cycle in percent
+static const struct FanPoint __code FAN2_POINTS[] = {
+#ifndef BOARD_FAN2_POINTS
+#error Board must declare fan points
+#else
+    BOARD_FAN2_POINTS
+#endif
+};
+
+static const struct Fan __code FAN2 = {
+    .points = FAN2_POINTS,
+    .points_size = ARRAY_SIZE(FAN2_POINTS),
+    .heatup = FAN2_HEATUP,
+    .heatup_size = ARRAY_SIZE(FAN2_HEATUP),
+    .cooldown = FAN2_COOLDOWN,
+    .cooldown_size = ARRAY_SIZE(FAN2_COOLDOWN),
+};
+
+#endif // FAN2_PWM
+
+// Get duty cycle based on temperature, adapted from
+// https://github.com/pop-os/system76-power/blob/master/src/fan.rs
+static uint8_t fan_duty(const struct Fan *const fan, int16_t temp) {
+    for (uint8_t i = 0; i < fan->points_size; i++) {
+        const struct FanPoint *cur = &fan->points[i];
+
+        // If exactly the current temp, return the current duty
+        if (temp == cur->temp) {
+            return cur->duty;
+        } else if (temp < cur->temp) {
+            // If lower than first temp, return 0%
+            if (i == 0) {
+                return 0;
+            } else {
+                const struct FanPoint *prev = &fan->points[i - 1];
+
+                // If in between current temp and previous temp, interpolate
+                if (temp > prev->temp) {
+                    int16_t dtemp = (cur->temp - prev->temp);
+                    int16_t dduty = ((int16_t)cur->duty) - ((int16_t)prev->duty);
+                    return (uint8_t)(
+                        ((int16_t)prev->duty) +
+                        ((temp - prev->temp) * dduty) / dtemp
+                    );
+                }
+            }
+        }
+    }
+
+    // If no point is found, return 100%
+    return CTR0;
+}
+
+static uint8_t fan_smooth(uint8_t last_duty, uint8_t duty) {
+    uint8_t next_duty = duty;
+
+    // ramping down
+    if (duty < last_duty) {
+        // out of bounds (lower) safeguard
+        uint8_t smoothed = last_duty < MIN_FAN_SPEED + MAX_JUMP_DOWN
+            ? MIN_FAN_SPEED
+            : last_duty - MAX_JUMP_DOWN;
+
+        // use smoothed value if above min and if smoothed is closer than raw
+        if (last_duty > MIN_SPEED_TO_SMOOTH && smoothed > duty) {
+            next_duty = smoothed;
+        }
+    }
+
+    // ramping up
+    if (duty > last_duty) {
+        // out of bounds (higher) safeguard
+        uint8_t smoothed = last_duty > MAX_FAN_SPEED - MAX_JUMP_UP
+            ? MAX_FAN_SPEED
+            : last_duty + MAX_JUMP_UP;
+
+        // use smoothed value if above min and if smoothed is closer than raw
+        if (duty > MIN_SPEED_TO_SMOOTH && smoothed < duty) {
+            next_duty = smoothed;
+        }
+    }
+
+    return next_duty;
+}
+
+static uint8_t fan_heatup(const struct Fan *const fan, uint8_t duty) {
+    uint8_t lowest = duty;
+
+    uint8_t i;
+    for (i = 0; (i + 1) < fan->heatup_size; i++) {
+        uint8_t value = fan->heatup[i + 1];
+        if (value < lowest) {
+            lowest = value;
+        }
+        fan->heatup[i] = value;
+    }
+    fan->heatup[i] = duty;
+
+    return lowest;
+}
+
+static uint8_t fan_cooldown(const struct Fan *const fan, uint8_t duty) {
+    uint8_t highest = duty;
+
+    uint8_t i;
+    for (i = 0; (i + 1) < fan->cooldown_size; i++) {
+        uint8_t value = fan->cooldown[i + 1];
+        if (value > highest) {
+            highest = value;
+        }
+        fan->cooldown[i] = value;
+    }
+    fan->cooldown[i] = duty;
+
+    return highest;
+}
+
+static uint8_t fan_get_duty(const struct Fan *const fan, int16_t temp) {
+    uint8_t duty;
+
+    if (power_state == POWER_STATE_S0) {
+        duty = fan_duty(fan, temp);
+        if (fan_max) {
+            duty = CTR0;
+        } else {
+            duty = fan_heatup(fan, duty);
+            duty = fan_cooldown(fan, duty);
+        }
+    } else {
+        duty = 0;
+    }
+
+    return duty;
+}
+
+void fan_event(void) {
+#if CONFIG_HAVE_DGPU
+    int16_t sys_temp = MAX(peci_temp, dgpu_temp);
+#else
+    int16_t sys_temp = peci_temp;
+#endif
+
+    // set FAN1 duty
+    fan1_pwm_target = fan_get_duty(&FAN1, sys_temp);
+    if (fan1_pwm_target != fan1_pwm_actual) {
+        TRACE("FAN1 target duty=%d\n", fan1_pwm_target);
+        last_fan1_duty = fan1_pwm_target = fan_smooth(last_fan1_duty, fan1_pwm_target);
+        fan1_pwm_actual = fan_max ? MAX_FAN_SPEED : fan1_pwm_target;
+        TRACE("FAN1 duty smoothed=%d\n", fan1_pwm_target);
+    }
+    FAN1_PWM = fan1_pwm_actual;
+    fan1_rpm = fan_get_tach0_rpm();
+
+#ifdef FAN2_PWM
+    // set FAN2 duty
+    fan2_pwm_target = fan_get_duty(&FAN2, sys_temp);
+    if (fan2_pwm_target != fan2_pwm_actual) {
+        TRACE("FAN2 target duty = %d\n", fan2_pwm_target);
+        last_fan2_duty = fan2_pwm_target = fan_smooth(last_fan2_duty, fan2_pwm_target);
+        fan2_pwm_actual = fan_max ? MAX_FAN_SPEED : fan2_pwm_target;
+        TRACE("FAN2 duty smoothed = %d\n", fan2_pwm_target);
+    }
+    FAN2_PWM = fan2_pwm_actual;
+    fan2_rpm = fan_get_tach1_rpm();
+#endif
+}