linux-postmarketos-omap: add N900 battery capacity estimation (MR 4388)

Provide a rough battery capacity estimation for the bq27200 fuel gauge inside
Nokia N900. This is useful when the fuel gauge is out of calibration and a
learning cycle cannot take place due to broken USB/charging port on the device.

[ci:skip-build]: Already built successfully in CI

device/community/linux-postmarketos-omap/0011-bq27xxx_battery-map-edv1-to-low-battery-capacity.patch

+From 350df21c4f01137e3d29f445e36aeb6c82b85e34 Mon Sep 17 00:00:00 2001
+From: "Sicelo A. Mhlongo" <absicsz@gmail.com>
+Date: Mon, 11 Sep 2023 10:34:54 +0200
+Subject: [PATCH 1/2] bq27xxx_battery: map edv1 to low battery capacity
+
+EDV1 is the most reliable indicator for battery low state on the N900/bq27200,
+and the driver already exposes it in the POWER_SUPPLY_PROP_CAPACITY_LEVEL (Low)
+and POWER_SUPPLY_PROP_HEALTH (Dead) properties. However, most userspace,
+including upower, does not use these properties for decision-making. Map EDV1
+state to very low battery capacity to force userspace to act on EDV1.
+
+Signed-off-by: Sicelo A. Mhlongo <absicsz@gmail.com>
+---
+ drivers/power/supply/bq27xxx_battery.c | 12 +++++++++++-
+ 1 file changed, 11 insertions(+), 1 deletion(-)
+
+diff --git a/drivers/power/supply/bq27xxx_battery.c b/drivers/power/supply/bq27xxx_battery.c
+index 4296600e8912..0789061ae9a0 100644
+--- a/drivers/power/supply/bq27xxx_battery.c
++++ b/drivers/power/supply/bq27xxx_battery.c
+@@ -1851,7 +1851,17 @@ static void bq27xxx_battery_update_unlocked(struct bq27xxx_device_info *di)
+ 			cache.time_to_full = bq27xxx_battery_read_time(di, BQ27XXX_REG_TTF);
+ 
+ 		cache.charge_full = bq27xxx_battery_read_fcc(di);
+-		cache.capacity = bq27xxx_battery_read_soc(di);
++
++		/* HACK: If EDV1 flag is set, force capacity to report 1%, even though
++		 * SEDV1 actually represents about 6.25%, per datasheet. This is to ensure
++		 * that userspace, such as upower, can readily react to the true battery low
++		 * state (EDV1 set) whether or not the reported SoC value is reliable.
++		 */
++		if (cache.flags & BQ27000_FLAG_EDV1)
++			cache.capacity = 1;
++		else
++			cache.capacity = bq27xxx_battery_read_soc(di);
++
+ 		if (di->regs[BQ27XXX_REG_AE] != INVALID_REG_ADDR)
+ 			cache.energy = bq27xxx_battery_read_energy(di);
+ 		di->cache.flags = cache.flags;
+-- 
+2.40.1
+

device/community/linux-postmarketos-omap/0012-bq27xxx_battery-add-voltage-based-capacity-estimatio.patch

+From 456b5d133e026811fd735096ff3884823279879c Mon Sep 17 00:00:00 2001
+From: "Sicelo A. Mhlongo" <absicsz@gmail.com>
+Date: Mon, 11 Sep 2023 11:14:56 +0200
+Subject: [PATCH] bq27xxx_battery: add voltage-based capacity estimation
+
+Use battery voltage to approximate the battery capacity, if the fuel gauge does
+not have valid data.
+
+Signed-off-by: Sicelo A. Mhlongo <absicsz@gmail.com>
+---
+ drivers/power/supply/bq27xxx_battery.c | 28 ++++++++++++++++++++++++--
+ 1 file changed, 26 insertions(+), 2 deletions(-)
+
+diff --git a/drivers/power/supply/bq27xxx_battery.c b/drivers/power/supply/bq27xxx_battery.c
+index 0789061ae9a0..9476caed0ef4 100644
+--- a/drivers/power/supply/bq27xxx_battery.c
++++ b/drivers/power/supply/bq27xxx_battery.c
+@@ -1017,6 +1017,8 @@ static struct {
+ 
+ static DEFINE_MUTEX(bq27xxx_list_lock);
+ static LIST_HEAD(bq27xxx_battery_devices);
++static int bq27xxx_battery_voltage(struct bq27xxx_device_info *di,
++				   union power_supply_propval *val);
+ 
+ #define BQ27XXX_MSLEEP(i) usleep_range((i)*1000, (i)*1000+500)
+ 
+@@ -1857,11 +1859,33 @@ static void bq27xxx_battery_update_unlocked(struct bq27xxx_device_info *di)
+ 		 * that userspace, such as upower, can readily react to the true battery low
+ 		 * state (EDV1 set) whether or not the reported SoC value is reliable.
+ 		 */
+-		if (cache.flags & BQ27000_FLAG_EDV1)
++		if (cache.flags & BQ27000_FLAG_EDV1) {
+ 			cache.capacity = 1;
+-		else
++		} else {
+ 			cache.capacity = bq27xxx_battery_read_soc(di);
+ 
++			/* Use voltage to estimate capacity if valid data is not available in the
++			 * fuel gauge.
++			 */
++			if ((cache.capacity == 0) &&
++			     bq27xxx_battery_capacity_inaccurate(di, cache.flags)) {
++				union power_supply_propval bqval;
++				bq27xxx_battery_voltage(di, &bqval);
++				if (bqval.intval > 4000000)
++					cache.capacity = 90;
++				else if (bqval.intval > 3840000)
++					cache.capacity = 80;
++				else if (bqval.intval > 3680000)
++					cache.capacity = 50;
++				else if (bqval.intval > 3550000)
++					cache.capacity = 30;
++				else if (bqval.intval > 3450000)
++					cache.capacity = 20;
++				else
++					cache.capacity = 10;
++			}
++		}
++
+ 		if (di->regs[BQ27XXX_REG_AE] != INVALID_REG_ADDR)
+ 			cache.energy = bq27xxx_battery_read_energy(di);
+ 		di->cache.flags = cache.flags;
+-- 
+2.40.1
+

device/community/linux-postmarketos-omap/APKBUILD

@@ -4,7 +4,7 @@
 
 pkgname=linux-postmarketos-omap
 pkgver=6.5
-pkgrel=0
+pkgrel=1
 pkgdesc="Mainline kernel fork for OMAP devices"
 arch="armv7"
 url="https://kernel.org/"
@@ -41,6 +41,8 @@ source="
 	0008-hsi-ssi_port-force-pio-path.patch
 	0009-n900-dts-volume-keys.patch
 	0010-ARM-dts-disable-twl-off-idle-configuration-for-N900.patch
+	0011-bq27xxx_battery-map-edv1-to-low-battery-capacity.patch
+	0012-bq27xxx_battery-add-voltage-based-capacity-estimatio.patch
 "
 builddir="$srcdir/linux-$pkgver"
 replaces="linux-samsung-espresso3g linux-nokia-n900"
@@ -81,4 +83,6 @@ f0bb41630d8e08adcffa433f3c82047e8787c96b7cc7301eb80bf5e5298010c136cd10c756278fb2
 c3af9715b3559c2d593f4fcfa078730722c7deeec132c5b83e085ff4d9815d85ef349384097c580efe1bbc37c60f42e18ef559f0abccfe236080670e4403fa77  0008-hsi-ssi_port-force-pio-path.patch
 b98ce806b3d5a0122086e4c9670639174470ff6d29851c60258cc5d699ce9a479dbf4996b24299fc075d25e9fe8f6b1250fafdff742deea0ddeaf53d342a9d72  0009-n900-dts-volume-keys.patch
 66abb5548910ad369608b08200f5835d5a8526c04cc3617221ef546f3e3d22cd944db91dc6727a5c26a102b24d8ef1306ea01254c9c382759afced91b31747ef  0010-ARM-dts-disable-twl-off-idle-configuration-for-N900.patch
+6680b264db0c992826f9da0078256ba20ffae3de26a77978106b94499d96e72ed90d9a35bb42be38bae1e798e7ddf068e3c5e7fe63462b3bbad5031195622192  0011-bq27xxx_battery-map-edv1-to-low-battery-capacity.patch
+cd91f0bb59e466c517b498a549357325be884bb1884986e593fef905a6210872024e0cab179df03833dfc6e8d1221441fa384466ae8227d82f6e70b22fce655c  0012-bq27xxx_battery-add-voltage-based-capacity-estimatio.patch
 "