[coreboot-gerrit] Change in coreboot[master]: drivers/i2c/lm96000: Add more settings for fan control

[Patrick Georgi (Code Review)]

Patrick Georgi has submitted this change. ( https://review.coreboot.org/c/coreboot/+/35475 )

Change subject: drivers/i2c/lm96000: Add more settings for fan control
......................................................................

drivers/i2c/lm96000: Add more settings for fan control

Allow to set a lower temperature limit, as the currently hard-coded
25C may be to low for a given temperature sensor. Also enable smoo-
thing, currently hard-coded to the maximum interval of 35s, and set
the hysteresis value.

Change-Id: I5fde1cf909e8fbbaf8a345790b00c58a73c19ef8
Signed-off-by: Nico Huber 
Reviewed-on: https://review.coreboot.org/c/coreboot/+/35475
Tested-by: build bot (Jenkins) 
Reviewed-by: Kyösti Mälkki 
---
M src/drivers/i2c/lm96000/chip.h
M src/drivers/i2c/lm96000/lm96000.c
2 files changed, 15 insertions(+), 4 deletions(-)

Approvals:
  build bot (Jenkins): Verified
  Kyösti Mälkki: Looks good to me, approved

diff --git a/src/drivers/i2c/lm96000/chip.h b/src/drivers/i2c/lm96000/chip.h
index ab782db..cbf8601 100644
--- a/src/drivers/i2c/lm96000/chip.h
+++ b/src/drivers/i2c/lm96000/chip.h
@@ -93,6 +93,7 @@
 };

struct lm96000_temp_zone {
+	u8 low_temp;	/* temperature for min. duty cycle (in °C) */
    u8 target_temp;	/* temperature for 100% duty cycle (in °C) */
    u8 panic_temp;	/* temperature for 100% duty cycle on all fans */

@@ -100,9 +101,12 @@
       with. (Datasheet clearly states the opposite, that this
       is tied to each PWM output so YMMV.) */
    enum {
-		LM96000_LOW_TEMP_OFF = 0, /* turn fan off below low temp. */
-		LM96000_LOW_TEMP_MIN = 1, /* keep PWM at mininum duty cycle */
+		/* turn fan off below `low_temp - hysteresis` */
+		LM96000_LOW_TEMP_OFF = 0,
+		/* keep PWM at mininum duty cycle */
+		LM96000_LOW_TEMP_MIN = 1,
    } min_off;
+	u8 hysteresis;
 };

/* Implements only those parts currently used by coreboot mainboards. */
diff --git a/src/drivers/i2c/lm96000/lm96000.c b/src/drivers/i2c/lm96000/lm96000.c
index 4a3c2eb..7fbb31b 100644
--- a/src/drivers/i2c/lm96000/lm96000.c
+++ b/src/drivers/i2c/lm96000/lm96000.c
@@ -156,9 +156,9 @@
    	{ 2, 3, 3, 4, 5, 7, 8, 10, 13, 16, 20, 27, 32, 40, 53, 80 };
    unsigned int i;

-	/* find longest range that starts from 25°C */
+	/* find longest range that starts from `low_temp` */
    for (i = ARRAY_SIZE(temp_range) - 1; i > 0; --i) {
-		if (temp_range[i] + 25 <= config->target_temp)
+		if (config->low_temp + temp_range[i] <= config->target_temp)
    		break;
    }

@@ -170,9 +170,16 @@
    	      : 0);
    lm96000_write(dev, LM96000_ZONE_TEMP_PANIC(zone),
    	      config->panic_temp ? config->panic_temp : 100);
+	lm96000_update(dev, LM96000_ZONE_SMOOTH(zone),
+		       LM96000_ZONE_SMOOTH_MASK(zone),
+		       LM96000_ZONE_SMOOTH_EN(zone) | 0); /* 0: 35s */
    lm96000_update(dev, LM96000_FAN_MIN_OFF,
    	       LM96000_FAN_MIN(zone),
    	       config->min_off ? LM96000_FAN_MIN(zone) : 0);
+	lm96000_update(dev, LM96000_ZONE_HYSTERESIS(zone),
+		       LM96000_ZONE_HYST_MASK(zone),
+		       config->hysteresis << LM96000_ZONE_HYST_SHIFT(zone)
+			& LM96000_ZONE_HYST_MASK(zone));
 }

static void lm96000_init(struct device *const dev)