Hardcode meaningful alert level, track apm's battery state better

The current code looks for the nonexistent "cellwise,alert-level" property
and falls back to zero as threshold (like the original NetBSD code).
It also updates the CONFIG register with that very threshold to let the
hardware set a bit and thus alert us when it has been reached.

Since our sensor framework is designed to poll every N seconds and this
driver does not actually look at whether the hardware alerted, neither
using a default threshold of zero nor updating the hardware with it makes
sense.

Remove the alert level code and simply map >50%, >25% and <=25% of
remaining battery life to apm(4)'s "high", "low" and "critical" battery
state respectively;  this matches exactly what acpibat(4) does and provides
more meaningful sensor readings without relying on nonexistent device tree
bindings.

Feedback OK patrick

1 files changed, 7 insertions, 23 deletions

diff --git a/sys/dev/fdt/cwfg.c b/sys/dev/fdt/cwfg.c
index 7940273e1a9..ad174fbf1ce 100644
--- a/sys/dev/fdt/cwfg.c
+++ b/sys/dev/fdt/cwfg.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: cwfg.c,v 1.4 2021/03/26 22:54:41 kn Exp $ */
+/* $OpenBSD: cwfg.c,v 1.5 2021/04/01 10:34:21 kn Exp $ */
 /* $NetBSD: cwfg.c,v 1.1 2020/01/03 18:00:05 jmcneill Exp $ */
 /*-
  * Copyright (c) 2020 Jared McNeill <jmcneill@invisible.ca>
@@ -58,8 +58,6 @@
 #define	 RTT_LO_MASK			0xff
 #define	 RTT_LO_SHIFT			0
 #define	CONFIG_REG		0x08
-#define	 CONFIG_ATHD_MASK		0x1f
-#define	 CONFIG_ATHD_SHIFT		3
 #define	 CONFIG_UFG			(1 << 1)
 #define	MODE_REG		0x0a
 #define	 MODE_SLEEP_MASK		(0x3 << 6)
@@ -91,7 +89,6 @@ struct cwfg_softc {
 
 	uint8_t		sc_batinfo[BATINFO_SIZE];
 
-	uint32_t	sc_alert_level;
 	uint32_t	sc_monitor_interval;
 	uint32_t	sc_design_capacity;
 
@@ -101,7 +98,6 @@ struct cwfg_softc {
 
 #define	CWFG_MONITOR_INTERVAL_DEFAULT	5000
 #define	CWFG_DESIGN_CAPACITY_DEFAULT	2000
-#define	CWFG_ALERT_LEVEL_DEFAULT	0
 
 int cwfg_match(struct device *, void *, void *);
 void cwfg_attach(struct device *, struct device *, void *);
@@ -189,8 +185,6 @@ cwfg_attach(struct device *parent, struct device *self, void *aux)
 	    "cellwise,monitor-interval-ms", CWFG_MONITOR_INTERVAL_DEFAULT);
 	sc->sc_design_capacity = OF_getpropint(sc->sc_node,
 	    "cellwise,design-capacity", CWFG_DESIGN_CAPACITY_DEFAULT);
-	sc->sc_alert_level = OF_getpropint(sc->sc_node,
-	    "cellwise,alert-level", CWFG_ALERT_LEVEL_DEFAULT);
 
 	if (cwfg_init(sc) != 0) {
 		printf(": failed to initialize device\n");
@@ -271,7 +265,6 @@ done:
 int
 cwfg_set_config(struct cwfg_softc *sc)
 {
-	uint32_t alert_level;
 	uint8_t config, mode, val;
 	int need_update;
 	int error, n;
@@ -280,19 +273,6 @@ cwfg_set_config(struct cwfg_softc *sc)
 	if ((error = cwfg_read(sc, CONFIG_REG, &config)) != 0)
 		return error;
 
-	/* Update alert level, if necessary */
-	alert_level = (config >> CONFIG_ATHD_SHIFT) & CONFIG_ATHD_MASK;
-	if (alert_level != sc->sc_alert_level) {
-		config &= ~(CONFIG_ATHD_MASK << CONFIG_ATHD_SHIFT);
-		config |= (sc->sc_alert_level << CONFIG_ATHD_SHIFT);
-		if ((error = cwfg_write(sc, CONFIG_REG, config)) != 0)
-			return error;
-	}
-
-	/* Re-read current config */
-	if ((error = cwfg_read(sc, CONFIG_REG, &config)) != 0)
-		return error;
-
 	/*
 	 * We need to upload a battery profile if either the UFG flag
 	 * is unset, or the current battery profile differs from the
@@ -387,9 +367,13 @@ cwfg_update_sensors(void *arg)
 		sc->sc_sensor[CWFG_SENSOR_SOC].value = val * 1000;
 		sc->sc_sensor[CWFG_SENSOR_SOC].flags &= ~SENSOR_FINVALID;
 #if NAPM > 0
-		cwfg_power.battery_state = val > sc->sc_alert_level ?
-		    APM_BATT_HIGH : APM_BATT_LOW;
 		cwfg_power.battery_life = val;
+		if (val > 50)
+			cwfg_power.battery_state = APM_BATT_HIGH;
+		else if (val > 25)
+			cwfg_power.battery_state = APM_BATT_LOW;
+		else
+			cwfg_power.battery_state = APM_BATT_CRITICAL;
 #endif
 	}