fan: Allow board to configure fans at run time

This patch splits struct fan_t into two parts: base configuration
and RPM configuration. RPMs are expected to be different from
model to model while a base configuration is most likely shared.

BUG=b:73720175
BRANCH=none
TEST=make buildall

Change-Id: Iff17573f110e07e88d097dd848cf91ee98b83176
Signed-off-by: Daisuke Nojiri <dnojiri@chromium.org>
Reviewed-on: https://chromium-review.googlesource.com/949382
Reviewed-by: Vincent Palatin <vpalatin@chromium.org>
Reviewed-on: https://chromium-review.googlesource.com/1083932

14 files changed, 262 insertions, 181 deletions

diff --git a/board/fizz/board.c b/board/fizz/board.c
index 0bde95bdfb..07ab85b841 100644
--- a/board/fizz/board.c
+++ b/board/fizz/board.c
@@ -150,16 +150,21 @@ BUILD_ASSERT(ARRAY_SIZE(adc_channels) == ADC_CH_COUNT);
 
 /******************************************************************************/
 /* Physical fans. These are logically separate from pwm_channels. */
-const struct fan_t fans[] = {
-	[FAN_CH_0] = {
-		.flags = FAN_USE_RPM_MODE,
-		.rpm_min = 2800,
-		.rpm_start = 2800,
-		.rpm_max = 5600,
-		.ch = MFT_CH_0,	/* Use MFT id to control fan */
-		.pgood_gpio = -1,
-		.enable_gpio = GPIO_FAN_PWR_EN,
-	},
+const struct fan_conf fan_conf_0 = {
+	.flags = FAN_USE_RPM_MODE,
+	.ch = MFT_CH_0,	/* Use MFT id to control fan */
+	.pgood_gpio = -1,
+	.enable_gpio = GPIO_FAN_PWR_EN,
+};
+
+const struct fan_rpm fan_rpm_0 = {
+	.rpm_min = 2800,
+	.rpm_start = 2800,
+	.rpm_max = 5600,
+};
+
+struct fan_t fans[] = {
+	[FAN_CH_0] = { .conf = &fan_conf_0, .rpm = &fan_rpm_0, },
 };
 BUILD_ASSERT(ARRAY_SIZE(fans) == FAN_CH_COUNT);
 
@@ -669,7 +674,7 @@ static int get_custom_rpm(int fan, int pct, int oem_id)
 	previous_pct = pct;
 
 	if (fan_table[current_level].rpm !=
-		fan_get_rpm_target(fans[fan].ch))
+		fan_get_rpm_target(FAN_CH(fan)))
 		cprintf(CC_THERMAL, "[%T Setting fan RPM to %d]\n",
 			fan_table[current_level].rpm);
 
diff --git a/board/host/fan.c b/board/host/fan.c
index ee7b15ef12..557baaaa7d 100644
--- a/board/host/fan.c
+++ b/board/host/fan.c
@@ -8,17 +8,22 @@
 #include "fan.h"
 #include "util.h"
 
-const struct fan_t fans[] = {
-	{.flags = FAN_USE_RPM_MODE,
-	 .rpm_min = 1000,
-	 .rpm_start = 1500,
-	 .rpm_max = 5000,
-	 .ch = 0,
-	 .pgood_gpio = -1,
-	 .enable_gpio = -1,
-	},
+const struct fan_conf fan_conf_0 = {
+	.flags = FAN_USE_RPM_MODE,
+	.ch = 0,
+	.pgood_gpio = -1,
+	.enable_gpio = -1,
+};
+
+const struct fan_rpm fan_rpm_0 = {
+	.rpm_min = 1000,
+	.rpm_start = 1500,
+	.rpm_max = 5000,
+};
+
+struct fan_t fans[CONFIG_FANS] = {
+	{ .conf = &fan_conf_0, .rpm = &fan_rpm_0, },
 };
-BUILD_ASSERT(ARRAY_SIZE(fans) == CONFIG_FANS);
 
 static int mock_enabled;
 void fan_set_enabled(int ch, int enabled)
diff --git a/board/it83xx_evb/board.c b/board/it83xx_evb/board.c
index cd0b9ff1e4..8bc2740beb 100644
--- a/board/it83xx_evb/board.c
+++ b/board/it83xx_evb/board.c
@@ -106,19 +106,21 @@ const struct pwm_t pwm_channels[] = {
 
 BUILD_ASSERT(ARRAY_SIZE(pwm_channels) == PWM_CH_COUNT);
 
-const struct fan_t fans[] = {
-	{.flags = FAN_USE_RPM_MODE,
-	 .rpm_min = 1500,
-	 .rpm_start = 1500,
-	 .rpm_max = 6500,
-	/*
-	 * index of pwm_channels, not pwm output channel.
-	 * pwm output channel is member "channel" of pwm_t.
-	 */
-	 .ch = 0,
-	 .pgood_gpio = -1,
-	 .enable_gpio = -1,
-	},
+const struct fan_conf fan_conf_0 = {
+	.flags = FAN_USE_RPM_MODE,
+	.ch = 0,	/* Use MFT id to control fan */
+	.pgood_gpio = -1,
+	.enable_gpio = -1,
+};
+
+const struct fan_rpm fan_rpm_0 = {
+	.rpm_min = 1500,
+	.rpm_start = 1500,
+	.rpm_max = 6500,
+};
+
+struct fan_t fans[] = {
+	{ .conf = &fan_conf_0, .rpm = &fan_rpm_0, },
 };
 BUILD_ASSERT(ARRAY_SIZE(fans) == CONFIG_FANS);
 
diff --git a/board/kahlee/board.c b/board/kahlee/board.c
index 1369dce43e..97a6ae40ce 100644
--- a/board/kahlee/board.c
+++ b/board/kahlee/board.c
@@ -132,16 +132,21 @@ BUILD_ASSERT(ARRAY_SIZE(pwm_channels) == PWM_CH_COUNT);
 
 /******************************************************************************/
 /* Physical fans. These are logically separate from pwm_channels. */
-const struct fan_t fans[] = {
-	[FAN_CH_0] = {
-		.flags = FAN_USE_RPM_MODE,
-		.rpm_min = 1000,
-		.rpm_start = 1000,
-		.rpm_max = 4300,
-		.ch = 0,/* Use MFT id to control fan */
-		.pgood_gpio = -1,
-		.enable_gpio = -1,
-	},
+const struct fan_conf fan_conf_0 = {
+	.flags = FAN_USE_RPM_MODE,
+	.ch = 0,	/* Use MFT id to control fan */
+	.pgood_gpio = -1,
+	.enable_gpio = -1,
+};
+
+const struct fan_rpm fan_rpm_0 = {
+	.rpm_min = 1000,
+	.rpm_start = 1000,
+	.rpm_max = 4300,
+};
+
+struct fan_t fans[] = {
+	[FAN_CH_0] = { .conf = &fan_conf_0, .rpm = &fan_rpm_0, },
 };
 BUILD_ASSERT(ARRAY_SIZE(fans) == FAN_CH_COUNT);
 
diff --git a/board/nami/board.c b/board/nami/board.c
index a5a9a1ac68..3c59dbb160 100644
--- a/board/nami/board.c
+++ b/board/nami/board.c
@@ -144,6 +144,33 @@ const struct adc_t adc_channels[] = {
 };
 BUILD_ASSERT(ARRAY_SIZE(adc_channels) == ADC_CH_COUNT);
 
+/******************************************************************************/
+/* Physical fans. These are logically separate from pwm_channels. */
+
+const struct fan_conf fan_conf_0 = {
+	.flags = FAN_USE_RPM_MODE,
+	.ch = MFT_CH_0,	/* Use MFT id to control fan */
+	.pgood_gpio = -1,
+	.enable_gpio = -1,
+};
+
+const struct fan_rpm fan_rpm_0 = {
+	.rpm_min = 2800,
+	.rpm_start = 3000,
+	.rpm_max = 6000,
+};
+
+struct fan_t fans[FAN_CH_COUNT] = {
+	[FAN_CH_0] = { .conf = &fan_conf_0, .rpm = &fan_rpm_0, },
+};
+
+/******************************************************************************/
+/* MFT channels. These are logically separate from pwm_channels. */
+const struct mft_t mft_channels[] = {
+	[MFT_CH_0] = {NPCX_MFT_MODULE_2, TCKC_LFCLK, PWM_CH_FAN},
+};
+BUILD_ASSERT(ARRAY_SIZE(mft_channels) == MFT_CH_COUNT);
+
 /* I2C port map */
 const struct i2c_port_t i2c_ports[]  = {
 	{"tcpc0",     NPCX_I2C_PORT0_0, 400, GPIO_I2C0_0_SCL, GPIO_I2C0_0_SDA},
diff --git a/board/npcx7_evb/board.c b/board/npcx7_evb/board.c
index 0a97942dbb..671671a21f 100644
--- a/board/npcx7_evb/board.c
+++ b/board/npcx7_evb/board.c
@@ -55,16 +55,21 @@ BUILD_ASSERT(ARRAY_SIZE(pwm_channels) == PWM_CH_COUNT);
 
 /******************************************************************************/
 /* Physical fans. These are logically separate from pwm_channels. */
-const struct fan_t fans[] = {
-	[FAN_CH_0] = {
-		.flags = FAN_USE_RPM_MODE,
-		.rpm_min = 1000,
-		.rpm_start = 1000,
-		.rpm_max = 5200,
-		.ch = 0,/* Use MFT id to control fan */
-		.pgood_gpio = GPIO_PGOOD_FAN,
-		.enable_gpio = -1,
-	},
+const struct fan_conf fan_conf_0 = {
+	.flags = FAN_USE_RPM_MODE,
+	.ch = 0,	/* Use MFT id to control fan */
+	.pgood_gpio = GPIO_PGOOD_FAN,
+	.enable_gpio = -1,
+};
+
+const struct fan_rpm fan_rpm_0 = {
+	.rpm_min = 1000,
+	.rpm_start = 1000,
+	.rpm_max = 5200,
+};
+
+struct fan_t fans[] = {
+	[FAN_CH_0] = { .conf = &fan_conf_0, .rpm = &fan_rpm_0, },
 };
 BUILD_ASSERT(ARRAY_SIZE(fans) == FAN_CH_COUNT);
 
diff --git a/board/npcx_evb/board.c b/board/npcx_evb/board.c
index 9a185ada2f..d4741fbe31 100644
--- a/board/npcx_evb/board.c
+++ b/board/npcx_evb/board.c
@@ -55,26 +55,36 @@ BUILD_ASSERT(ARRAY_SIZE(pwm_channels) == PWM_CH_COUNT);
 
 /******************************************************************************/
 /* Physical fans. These are logically separate from pwm_channels. */
-const struct fan_t fans[] = {
-	[FAN_CH_0] = {
-		.flags = FAN_USE_RPM_MODE,
-		.rpm_min = 1000,
-		.rpm_start = 1000,
-		.rpm_max = 5200,
-		.ch = 0,/* Use MFT id to control fan */
-		.pgood_gpio = GPIO_PGOOD_FAN,
-		.enable_gpio = -1,
-	},
+const struct fan_conf fan_conf_0 = {
+	.flags = FAN_USE_RPM_MODE,
+	.ch = 0,	/* Use MFT id to control fan */
+	.pgood_gpio = GPIO_PGOOD_FAN,
+	.enable_gpio = -1,
+};
+
+const struct fan_conf fan_conf_1 = {
+	.flags = FAN_USE_RPM_MODE,
+	.ch = 1,	/* Use MFT id to control fan */
+	.pgood_gpio = -1,
+	.enable_gpio = -1,
+};
+
+const struct fan_rpm fan_rpm_0 = {
+	.rpm_min = 1000,
+	.rpm_start = 1000,
+	.rpm_max = 5200,
+};
+
+const struct fan_rpm fan_rpm_1 = {
+	.rpm_min = 1000,
+	.rpm_start = 1000,
+	.rpm_max = 4300,
+};
+
+struct fan_t fans[] = {
+	[FAN_CH_0] = { .conf = &fan_conf_0, .rpm = &fan_rpm_0, },
 #if (CONFIG_FANS == 2)
-	[FAN_CH_1] = {
-		.flags = FAN_USE_RPM_MODE,
-		.rpm_min = 1000,
-		.rpm_start = 1000,
-		.rpm_max = 4300,
-		.ch = 1,/* Use MFT id to control fan */
-		.pgood_gpio = -1,
-		.enable_gpio = -1,
-	},
+	[FAN_CH_1] = { .conf = &fan_conf_1, .rpm = &fan_rpm_1, },
 #endif
 };
 BUILD_ASSERT(ARRAY_SIZE(fans) == FAN_CH_COUNT);
diff --git a/board/npcx_evb_arm/board.c b/board/npcx_evb_arm/board.c
index 9e3ae7d0dd..da4d55a3bd 100644
--- a/board/npcx_evb_arm/board.c
+++ b/board/npcx_evb_arm/board.c
@@ -52,16 +52,21 @@ BUILD_ASSERT(ARRAY_SIZE(pwm_channels) == PWM_CH_COUNT);
 
 /******************************************************************************/
 /* Physical fans. These are logically separate from pwm_channels. */
-const struct fan_t fans[] = {
-	[FAN_CH_0] = {
-		.flags = FAN_USE_RPM_MODE,
-		.rpm_min = 1000,
-		.rpm_start = 1000,
-		.rpm_max = 5200,
-		.ch = 0,/* Use MFT id to control fan */
-		.pgood_gpio = GPIO_PGOOD_FAN,
-		.enable_gpio = -1,
-	},
+const struct fan_conf fan_conf_0 = {
+	.flags = FAN_USE_RPM_MODE,
+	.ch = 0,	/* Use MFT id to control fan */
+	.pgood_gpio = GPIO_PGOOD_FAN,
+	.enable_gpio = -1,
+};
+
+const struct fan_rpm fan_rpm_0 = {
+	.rpm_min = 1000,
+	.rpm_start = 1000,
+	.rpm_max = 5200,
+};
+
+struct fan_t fans[] = {
+	[FAN_CH_0] = { .conf = &fan_conf_0, .rpm = &fan_rpm_0, },
 };
 BUILD_ASSERT(ARRAY_SIZE(fans) == FAN_CH_COUNT);
 
diff --git a/board/samus/board.c b/board/samus/board.c
index db49a573af..167b20093c 100644
--- a/board/samus/board.c
+++ b/board/samus/board.c
@@ -96,23 +96,29 @@ const struct pwm_t pwm_channels[] = {
 BUILD_ASSERT(ARRAY_SIZE(pwm_channels) == PWM_CH_COUNT);
 
 /* Physical fans. These are logically separate from pwm_channels. */
-const struct fan_t fans[] = {
-	{.flags = FAN_USE_RPM_MODE,
-	 .rpm_min = 1000,
-	 .rpm_start = 1000,
-	 .rpm_max = 6350,
-	 .ch = 2,
-	 .pgood_gpio = -1,
-	 .enable_gpio = -1,
-	},
-	{.flags = FAN_USE_RPM_MODE,
-	 .rpm_min = 1000,
-	 .rpm_start = 1000,
-	 .rpm_max = 6350,
-	 .ch = 3,
-	 .pgood_gpio = -1,
-	 .enable_gpio = -1,
-	},
+const struct fan_conf fan_conf_0 = {
+	.flags = FAN_USE_RPM_MODE,
+	.ch = 2,	/* Use MFT id to control fan */
+	.pgood_gpio = -1,
+	.enable_gpio = -1,
+};
+
+const struct fan_conf fan_conf_1 = {
+	.flags = FAN_USE_RPM_MODE,
+	.ch = 3,	/* Use MFT id to control fan */
+	.pgood_gpio = -1,
+	.enable_gpio = -1,
+};
+
+const struct fan_rpm fan_rpm_0 = {
+	.rpm_min = 1000,
+	.rpm_start = 1000,
+	.rpm_max = 6350,
+};
+
+struct fan_t fans[] = {
+	{ .conf = &fan_conf_0, .rpm = &fan_rpm_0, },
+	{ .conf = &fan_conf_1, .rpm = &fan_rpm_0, },
 };
 BUILD_ASSERT(ARRAY_SIZE(fans) == CONFIG_FANS);
 
diff --git a/chip/it83xx/fan.c b/chip/it83xx/fan.c
index d412e14123..d8cf010695 100644
--- a/chip/it83xx/fan.c
+++ b/chip/it83xx/fan.c
@@ -98,7 +98,7 @@ static int fan_all_disabled(void)
 	int fan, all_disabled = 0;
 
 	for (fan = 0; fan < CONFIG_FANS; fan++) {
-		if (!fan_get_enabled(fans[fan].ch))
+		if (!fan_get_enabled(FAN_CH(fan)))
 			all_disabled++;
 	}
 
@@ -423,9 +423,9 @@ void fan_ext_timer_interrupt(void)
 	task_clear_pending_irq(et_ctrl_regs[FAN_CTRL_EXT_TIMER].irq);
 
 	for (fan = 0; fan < CONFIG_FANS; fan++) {
-		if (fan_get_enabled(fans[fan].ch)) {
-			proc_tach(fans[fan].ch);
-			fan_ctrl(fans[fan].ch);
+		if (fan_get_enabled(FAN_CH(fan))) {
+			proc_tach(FAN_CH(fan));
+			fan_ctrl(FAN_CH(fan));
 		}
 	}
 }
@@ -437,10 +437,10 @@ static void fan_init(void)
 
 	for (ch = 0; ch < CONFIG_FANS; ch++) {
 
-		rpm_re = fan_tach[pwm_channels[fans[ch].ch].channel].rpm_re;
-		fan_p = fan_tach[pwm_channels[fans[ch].ch].channel].fan_p;
-		s_duty = fan_tach[pwm_channels[fans[ch].ch].channel].s_duty;
-		tach_ch = tach_bind(fans[ch].ch);
+		rpm_re = fan_tach[pwm_channels[FAN_CH(ch)].channel].rpm_re;
+		fan_p = fan_tach[pwm_channels[FAN_CH(ch)].channel].fan_p;
+		s_duty = fan_tach[pwm_channels[FAN_CH(ch)].channel].s_duty;
+		tach_ch = tach_bind(FAN_CH(ch));
 
 		if (tach_ch < TACH_CH_COUNT) {
 
diff --git a/chip/npcx/fan.c b/chip/npcx/fan.c
index 8e08e4ec58..a92b01e60c 100644
--- a/chip/npcx/fan.c
+++ b/chip/npcx/fan.c
@@ -492,10 +492,10 @@ void fan_set_rpm_target(int ch, int rpm)
 	/* If rpm = 0, disable PWM */
 	if (rpm == 0)
 		fan_set_duty(ch, 0);
-	else if (rpm > fans[ch].rpm_max)
-		rpm = fans[ch].rpm_max;
-	else if (rpm < fans[ch].rpm_min)
-		rpm = fans[ch].rpm_min;
+	else if (rpm > fans[ch].rpm->rpm_max)
+		rpm = fans[ch].rpm->rpm_max;
+	else if (rpm < fans[ch].rpm->rpm_min)
+		rpm = fans[ch].rpm->rpm_min;
 
 	/* Set target rpm */
 	fan_status[ch].rpm_target = rpm;
diff --git a/common/fan.c b/common/fan.c
index 5e2f85475f..d193240150 100644
--- a/common/fan.c
+++ b/common/fan.c
@@ -37,8 +37,8 @@ int fan_percent_to_rpm(int fan, int pct)
 	if (!pct) {
 		rpm = 0;
 	} else {
-		min = fans[fan].rpm_min;
-		max = fans[fan].rpm_max;
+		min = fans[fan].rpm->rpm_min;
+		max = fans[fan].rpm->rpm_max;
 		rpm = ((pct - 1) * max + (100 - pct) * min) / 99;
 	}
 
@@ -62,25 +62,25 @@ test_mockable void fan_set_percent_needed(int fan, int pct)
 #endif
 
 	new_rpm = fan_percent_to_rpm(fan, pct);
-	actual_rpm = fan_get_rpm_actual(fans[fan].ch);
+	actual_rpm = fan_get_rpm_actual(FAN_CH(fan));
 
 	/* If we want to turn and the fans are currently significantly below
 	 * the minimum turning speed, we should turn at least as fast as the
 	 * necessary start speed instead. */
 	if (new_rpm &&
-	    actual_rpm < fans[fan].rpm_min * 9 / 10 &&
-	    new_rpm < fans[fan].rpm_start)
-		new_rpm = fans[fan].rpm_start;
+	    actual_rpm < fans[fan].rpm->rpm_min * 9 / 10 &&
+	    new_rpm < fans[fan].rpm->rpm_start)
+		new_rpm = fans[fan].rpm->rpm_start;
 
-	fan_set_rpm_target(fans[fan].ch, new_rpm);
+	fan_set_rpm_target(FAN_CH(fan), new_rpm);
 }
 
 static void set_enabled(int fan, int enable)
 {
-	fan_set_enabled(fans[fan].ch, enable);
+	fan_set_enabled(FAN_CH(fan), enable);
 
-	if (fans[fan].enable_gpio >= 0)
-		gpio_set_level(fans[fan].enable_gpio, enable);
+	if (fans[fan].conf->enable_gpio >= 0)
+		gpio_set_level(fans[fan].conf->enable_gpio, enable);
 }
 
 static void set_thermal_control_enabled(int fan, int enable)
@@ -89,13 +89,13 @@ static void set_thermal_control_enabled(int fan, int enable)
 
 	/* If controlling the fan, need it in RPM-control mode */
 	if (enable)
-		fan_set_rpm_mode(fans[fan].ch, 1);
+		fan_set_rpm_mode(FAN_CH(fan), 1);
 }
 
 static void set_duty_cycle(int fan, int percent)
 {
 	/* Move the fan to manual control */
-	fan_set_rpm_mode(fans[fan].ch, 0);
+	fan_set_rpm_mode(FAN_CH(fan), 0);
 
 	/* enable the fan when non-zero duty */
 	set_enabled(fan, (percent > 0) ? 1 : 0);
@@ -104,7 +104,7 @@ static void set_duty_cycle(int fan, int percent)
 	set_thermal_control_enabled(fan, 0);
 
 	/* Set the duty cycle */
-	fan_set_duty(fans[fan].ch, percent);
+	fan_set_duty(FAN_CH(fan), percent);
 }
 
 /*****************************************************************************/
@@ -140,11 +140,11 @@ static int is_powered(int fan)
 	int is_pgood = -1;
 
 	/* If we have an enable output, see if it's on or off. */
-	if (fans[fan].enable_gpio >= 0)
-		is_pgood = gpio_get_level(fans[fan].enable_gpio);
+	if (fans[fan].conf->enable_gpio >= 0)
+		is_pgood = gpio_get_level(fans[fan].conf->enable_gpio);
 	/* If we have a pgood input, it overrides any enable output. */
-	if (fans[fan].pgood_gpio >= 0)
-		is_pgood = gpio_get_level(fans[fan].pgood_gpio);
+	if (fans[fan].conf->pgood_gpio >= 0)
+		is_pgood = gpio_get_level(fans[fan].conf->pgood_gpio);
 
 	return is_pgood;
 }
@@ -163,20 +163,20 @@ static int cc_faninfo(int argc, char **argv)
 		if (fan)
 			ccprintf("\n");
 		ccprintf("%sActual: %4d rpm\n", leader,
-			 fan_get_rpm_actual(fans[fan].ch));
+			 fan_get_rpm_actual(FAN_CH(fan)));
 		ccprintf("%sTarget: %4d rpm\n", leader,
-			 fan_get_rpm_target(fans[fan].ch));
+			 fan_get_rpm_target(FAN_CH(fan)));
 		ccprintf("%sDuty:   %d%%\n", leader,
-			 fan_get_duty(fans[fan].ch));
-		tmp = fan_get_status(fans[fan].ch);
+			 fan_get_duty(FAN_CH(fan)));
+		tmp = fan_get_status(FAN_CH(fan));
 		ccprintf("%sStatus: %d (%s)\n", leader,
 			 tmp, human_status[tmp]);
 		ccprintf("%sMode:   %s\n", leader,
-			 fan_get_rpm_mode(fans[fan].ch) ? "rpm" : "duty");
+			 fan_get_rpm_mode(FAN_CH(fan)) ? "rpm" : "duty");
 		ccprintf("%sAuto:   %s\n", leader,
 			 thermal_control_enabled[fan] ? "yes" : "no");
 		ccprintf("%sEnable: %s\n", leader,
-			 fan_get_enabled(fans[fan].ch) ? "yes" : "no");
+			 fan_get_enabled(FAN_CH(fan)) ? "yes" : "no");
 		is_pgood = is_powered(fan);
 		if (is_pgood >= 0)
 			ccprintf("%sPower:  %s\n", leader,
@@ -223,7 +223,7 @@ static int cc_fanset(int argc, char **argv)
 	}
 
 	/* Move the fan to automatic control */
-	fan_set_rpm_mode(fans[fan].ch, 1);
+	fan_set_rpm_mode(FAN_CH(fan), 1);
 
 	/* enable the fan when non-zero rpm */
 	set_enabled(fan, (rpm > 0) ? 1 : 0);
@@ -231,7 +231,7 @@ static int cc_fanset(int argc, char **argv)
 	/* Disable thermal engine automatic fan control. */
 	set_thermal_control_enabled(fan, 0);
 
-	fan_set_rpm_target(fans[fan].ch, rpm);
+	fan_set_rpm_target(FAN_CH(fan), rpm);
 
 	ccprintf("Setting fan %d rpm target to %d\n", fan, rpm);
 
@@ -283,10 +283,10 @@ int dptf_get_fan_duty_target(void)
 {
 	int fan = 0;				/* TODO(crosbug.com/p/23803) */
 
-	if (thermal_control_enabled[fan] || fan_get_rpm_mode(fans[fan].ch))
+	if (thermal_control_enabled[fan] || fan_get_rpm_mode(FAN_CH(fan)))
 		return -1;
 
-	return fan_get_duty(fans[fan].ch);
+	return fan_get_duty(FAN_CH(fan));
 }
 
 /* 0-100% sets duty, out of range means let the EC drive */
@@ -314,7 +314,7 @@ static int hc_pwm_get_fan_target_rpm(struct host_cmd_handler_args *args)
 	int fan = 0;
 
 	/* TODO(crosbug.com/p/23803) */
-	r->rpm = fan_get_rpm_target(fans[fan].ch);
+	r->rpm = fan_get_rpm_target(FAN_CH(fan));
 	args->response_size = sizeof(*r);
 
 	return EC_RES_SUCCESS;
@@ -335,8 +335,8 @@ static int hc_pwm_set_fan_target_rpm(struct host_cmd_handler_args *args)
 			set_enabled(fan, (p_v0->rpm > 0) ? 1 : 0);
 
 			set_thermal_control_enabled(fan, 0);
-			fan_set_rpm_mode(fans[fan].ch, 1);
-			fan_set_rpm_target(fans[fan].ch, p_v0->rpm);
+			fan_set_rpm_mode(FAN_CH(fan), 1);
+			fan_set_rpm_target(FAN_CH(fan), p_v0->rpm);
 		}
 
 		return EC_RES_SUCCESS;
@@ -350,8 +350,8 @@ static int hc_pwm_set_fan_target_rpm(struct host_cmd_handler_args *args)
 	set_enabled(fan, (p_v1->rpm > 0) ? 1 :0);
 
 	set_thermal_control_enabled(fan, 0);
-	fan_set_rpm_mode(fans[fan].ch, 1);
-	fan_set_rpm_target(fans[fan].ch, p_v1->rpm);
+	fan_set_rpm_mode(FAN_CH(fan), 1);
+	fan_set_rpm_target(FAN_CH(fan), p_v1->rpm);
 
 	return EC_RES_SUCCESS;
 }
@@ -436,21 +436,21 @@ static void pwm_fan_init(void)
 	int fan = 0;
 
 	for (fan = 0; fan < CONFIG_FANS; fan++)
-		fan_channel_setup(fans[fan].ch, fans[fan].flags);
+		fan_channel_setup(FAN_CH(fan), fans[fan].conf->flags);
 
 	prev = (const struct pwm_fan_state *)
 		system_get_jump_tag(PWMFAN_SYSJUMP_TAG, &version, &size);
 	if (prev && version == PWM_HOOK_VERSION && size == sizeof(*prev)) {
 		/* Restore previous state. */
 		for (fan = 0; fan < CONFIG_FANS; fan++) {
-			fan_set_enabled(fans[fan].ch, prev->fan_en);
-			fan_set_rpm_target(fans[fan].ch, prev->fan_rpm);
+			fan_set_enabled(FAN_CH(fan), prev->fan_en);
+			fan_set_rpm_target(FAN_CH(fan), prev->fan_rpm);
 		}
 	} else {
 		/* Set initial fan speed */
 		for (fan = 0; fan < CONFIG_FANS; fan++)
-			fan_set_rpm_target(fans[fan].ch,
-				fan_percent_to_rpm(fans[fan].ch,
+			fan_set_rpm_target(FAN_CH(fan),
+				fan_percent_to_rpm(FAN_CH(fan),
 				CONFIG_FAN_INIT_SPEED));
 	}
 
@@ -472,12 +472,12 @@ static void pwm_fan_second(void)
 	int fan;
 
 	for (fan = 0; fan < CONFIG_FANS; fan++) {
-		if (fan_is_stalled(fans[fan].ch)) {
+		if (fan_is_stalled(FAN_CH(fan))) {
 			rpm = EC_FAN_SPEED_STALLED;
 			stalled = 1;
 			cprints(CC_PWM, "Fan %d stalled!", fan);
 		} else {
-			rpm = fan_get_rpm_actual(fans[fan].ch);
+			rpm = fan_get_rpm_actual(FAN_CH(fan));
 		}
 
 		mapped[fan] = rpm;
@@ -498,8 +498,8 @@ static void pwm_fan_preserve_state(void)
 	int fan = 0;
 
 	/* TODO(crosbug.com/p/23530): Still treating all fans as one. */
-	state.fan_en = fan_get_enabled(fans[fan].ch);
-	state.fan_rpm = fan_get_rpm_target(fans[fan].ch);
+	state.fan_en = fan_get_enabled(FAN_CH(fan));
+	state.fan_rpm = fan_get_rpm_target(FAN_CH(fan));
 
 	system_add_jump_tag(PWMFAN_SYSJUMP_TAG, PWM_HOOK_VERSION,
 			    sizeof(state), &state);
@@ -515,7 +515,7 @@ static void pwm_fan_resume(void)
 #else
 		set_thermal_control_enabled(fan, 0);
 #endif
-		fan_set_rpm_target(fans[fan].ch, fans[fan].rpm_max);
+		fan_set_rpm_target(FAN_CH(fan), fans[fan].rpm->rpm_max);
 		set_enabled(fan, 1);
 	}
 }
@@ -533,7 +533,7 @@ static void pwm_fan_S3_S5(void)
 		 * again if we need active cooling during heavy battery
 		 * charging or something.
 		 */
-		fan_set_rpm_target(fans[fan].ch, 0);
+		fan_set_rpm_target(FAN_CH(fan), 0);
 		set_enabled(fan, 0); /* crosbug.com/p/8097 */
 	}
 }
diff --git a/include/fan.h b/include/fan.h
index bd94ba8bd1..86c2822f80 100644
--- a/include/fan.h
+++ b/include/fan.h
@@ -8,13 +8,8 @@
 #ifndef __CROS_EC_FAN_H
 #define __CROS_EC_FAN_H
 
-/* Characteristic of each physical fan */
-struct fan_t {
+struct fan_conf {
 	unsigned int flags;
-	/* rpm_min is to keep turning. rpm_start is to begin turning */
-	int rpm_min;
-	int rpm_start;
-	int rpm_max;
 	/* Hardware channel number (the meaning is chip-specific) */
 	int ch;
 	/* Active-high power_good input GPIO, or -1 if none */
@@ -23,6 +18,19 @@ struct fan_t {
 	int enable_gpio;
 };
 
+struct fan_rpm {
+	/* rpm_min is to keep turning. rpm_start is to begin turning */
+	int rpm_min;
+	int rpm_start;
+	int rpm_max;
+};
+
+/* Characteristic of each physical fan */
+struct fan_t {
+	const struct fan_conf *conf;
+	const struct fan_rpm *rpm;
+};
+
 /* Values for .flags field */
 /*   Enable automatic RPM control using tach input */
 #define FAN_USE_RPM_MODE   (1 << 0)
@@ -30,8 +38,10 @@ struct fan_t {
 #define FAN_USE_FAST_START (1 << 1)
 
 /* The list of fans is instantiated in board.c. */
-extern const struct fan_t fans[];
+extern struct fan_t fans[];
 
+/* For convenience */
+#define FAN_CH(fan)	fans[fan].conf->ch
 
 /**
  * Set the amount of active cooling needed. The thermal control task will call
diff --git a/test/fan.c b/test/fan.c
index 9a0fa0d225..6082de1553 100644
--- a/test/fan.c
+++ b/test/fan.c
@@ -17,6 +17,7 @@
 #include "timer.h"
 #include "util.h"
 
+#define FAN_RPM(fan)	fans[fan].rpm
 
 /*****************************************************************************/
 /* Tests */
@@ -29,7 +30,7 @@ static int test_fan(void)
 	sleep(2);
 
 	/* With nothing else to do, fans default to full-on */
-	TEST_ASSERT(fan_get_rpm_actual(0) == fans[0].rpm_max);
+	TEST_ASSERT(fan_get_rpm_actual(0) == FAN_RPM(0)->rpm_max);
 
 	/*
 	 * fan_set_percent_needed() is normally called once a second by the
@@ -46,22 +47,22 @@ static int test_fan(void)
 
 	/* On, but just barely */
 	fan_set_percent_needed(0, 1);
-	TEST_ASSERT(fan_get_rpm_actual(0) == fans[0].rpm_start);
+	TEST_ASSERT(fan_get_rpm_actual(0) == FAN_RPM(0)->rpm_start);
 	/* fan is above min speed now, so should be set to min */
 	fan_set_percent_needed(0, 1);
-	TEST_ASSERT(fan_get_rpm_actual(0) == fans[0].rpm_min);
+	TEST_ASSERT(fan_get_rpm_actual(0) == FAN_RPM(0)->rpm_min);
 
 	/* Full speed */
 	fan_set_percent_needed(0, 100);
-	TEST_ASSERT(fan_get_rpm_actual(0) == fans[0].rpm_max);
+	TEST_ASSERT(fan_get_rpm_actual(0) == FAN_RPM(0)->rpm_max);
 	fan_set_percent_needed(0, 100);
-	TEST_ASSERT(fan_get_rpm_actual(0) == fans[0].rpm_max);
+	TEST_ASSERT(fan_get_rpm_actual(0) == FAN_RPM(0)->rpm_max);
 
 	/* Slow again */
 	fan_set_percent_needed(0, 1);
-	TEST_ASSERT(fan_get_rpm_actual(0) == fans[0].rpm_min);
+	TEST_ASSERT(fan_get_rpm_actual(0) == FAN_RPM(0)->rpm_min);
 	fan_set_percent_needed(0, 1);
-	TEST_ASSERT(fan_get_rpm_actual(0) == fans[0].rpm_min);
+	TEST_ASSERT(fan_get_rpm_actual(0) == FAN_RPM(0)->rpm_min);
 
 	/* Off */
 	fan_set_percent_needed(0, 0);
@@ -71,31 +72,31 @@ static int test_fan(void)
 
 	/* On, but just barely */
 	fan_set_percent_needed(0, 1);
-	TEST_ASSERT(fan_get_rpm_actual(0) == fans[0].rpm_start);
+	TEST_ASSERT(fan_get_rpm_actual(0) == FAN_RPM(0)->rpm_start);
 	/* Force the mock_rpm to be slow, to simulate dragging */
-	mock_rpm = fans[0].rpm_min - 105;
+	mock_rpm = FAN_RPM(0)->rpm_min - 105;
 	/* It should keep trying for the start speed */
 	fan_set_percent_needed(0, 1);
-	TEST_ASSERT(fan_get_rpm_actual(0) == fans[0].rpm_start);
+	TEST_ASSERT(fan_get_rpm_actual(0) == FAN_RPM(0)->rpm_start);
 	/* But we have to keep forcing the mock_rpm back down */
-	mock_rpm = fans[0].rpm_min - 105;
+	mock_rpm = FAN_RPM(0)->rpm_min - 105;
 	fan_set_percent_needed(0, 1);
-	TEST_ASSERT(fan_get_rpm_actual(0) == fans[0].rpm_start);
+	TEST_ASSERT(fan_get_rpm_actual(0) == FAN_RPM(0)->rpm_start);
 	/* Now let it turn just under rpm_min. Should be okay there. */
-	mock_rpm = fans[0].rpm_min - 10;
+	mock_rpm = FAN_RPM(0)->rpm_min - 10;
 	fan_set_percent_needed(0, 1);
-	TEST_ASSERT(fan_get_rpm_actual(0) == fans[0].rpm_min);
+	TEST_ASSERT(fan_get_rpm_actual(0) == FAN_RPM(0)->rpm_min);
 	/* Let it go a little faster, still okay */
-	mock_rpm = fans[0].rpm_min + 10;
+	mock_rpm = FAN_RPM(0)->rpm_min + 10;
 	fan_set_percent_needed(0, 1);
-	TEST_ASSERT(fan_get_rpm_actual(0) == fans[0].rpm_min);
+	TEST_ASSERT(fan_get_rpm_actual(0) == FAN_RPM(0)->rpm_min);
 	/* But if it drops too low, it should go back to the start speed */
-	mock_rpm = fans[0].rpm_min - 105;
+	mock_rpm = FAN_RPM(0)->rpm_min - 105;
 	fan_set_percent_needed(0, 1);
-	TEST_ASSERT(fan_get_rpm_actual(0) == fans[0].rpm_start);
+	TEST_ASSERT(fan_get_rpm_actual(0) == FAN_RPM(0)->rpm_start);
 	/* And then relax */
 	fan_set_percent_needed(0, 1);
-	TEST_ASSERT(fan_get_rpm_actual(0) == fans[0].rpm_min);
+	TEST_ASSERT(fan_get_rpm_actual(0) == FAN_RPM(0)->rpm_min);
 
 	return EC_SUCCESS;
 }