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Date: Mon, 29 Jan 2024 16:36:21 +0000
To: linux-kernel@vger.kernel.org, platform-driver-x86@vger.kernel.org, jwoithe@just42.net, hdegoede@redhat.com, ilpo.jarvinen@linux.intel.com
From: Szilard Fabian <szfabian@bluemarch.art>
Cc: Szilard Fabian <szfabian@bluemarch.art>
Subject: [RFC PATCH] platform/x86/fujitsu-laptop: Add battery charge control support
Message-ID: <20240129163502.161409-2-szfabian@bluemarch.art>
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This patch adds battery charge control support on Fujitsu notebooks
via the S006 method of the FUJ02E3 ACPI device. With this method it's
possible to set charge_control_end_threshold between 50 and 100%.

Tested on Lifebook E5411 and Lifebook U728. Sadly I can't test this
patch on a dual battery one, but I didn't find any clue about
independent battery charge control on dual battery Fujitsu notebooks
either. And by that I mean checking the DSDT table of various Lifebook
notebooks and reverse engineering FUJ02E3.dll.
---
 drivers/platform/x86/fujitsu-laptop.c | 95 +++++++++++++++++++++++++++
 1 file changed, 95 insertions(+)

diff --git a/drivers/platform/x86/fujitsu-laptop.c b/drivers/platform/x86/f=
ujitsu-laptop.c
index 085e044e888e..bf3df74e4d63 100644
--- a/drivers/platform/x86/fujitsu-laptop.c
+++ b/drivers/platform/x86/fujitsu-laptop.c
@@ -49,6 +49,8 @@
 #include <linux/kfifo.h>
 #include <linux/leds.h>
 #include <linux/platform_device.h>
+#include <linux/power_supply.h>
+#include <acpi/battery.h>
 #include <acpi/video.h>
=20
 #define FUJITSU_DRIVER_VERSION=09=09"0.6.0"
@@ -97,6 +99,10 @@
 #define BACKLIGHT_OFF=09=09=09(BIT(0) | BIT(1))
 #define BACKLIGHT_ON=09=09=090
=20
+/* FUNC interface - battery control interface */
+#define FUNC_S006_METHOD=09=090x1006
+#define CHARGE_CONTROL_RW=09=090x21
+
 /* Scancodes read from the GIRB register */
 #define KEY1_CODE=09=09=090x410
 #define KEY2_CODE=09=09=090x411
@@ -164,6 +170,91 @@ static int call_fext_func(struct acpi_device *device,
 =09return value;
 }
=20
+/* Battery charge control code */
+
+static ssize_t charge_control_end_threshold_store(struct device *dev,
+=09=09=09=09struct device_attribute *attr,
+=09=09=09=09const char *buf, size_t count)
+{
+=09int value, ret;
+
+=09ret =3D kstrtouint(buf, 10, &value);
+=09if (ret)
+=09=09return ret;
+
+=09if (value < 50 || value > 100)
+=09=09return -EINVAL;
+
+=09int cc_end_value, s006_cc_return;
+
+=09cc_end_value =3D value * 0x100 + 0x20;
+=09s006_cc_return =3D call_fext_func(fext, FUNC_S006_METHOD,
+=09=09=09=09=09CHARGE_CONTROL_RW, cc_end_value, 0x0);
+
+=09/*
+=09 * The S006 0x21 method returns 0x00 in case the provided value
+=09 * is invalid.
+=09 */
+=09if (s006_cc_return =3D=3D 0x00)
+=09=09return -EINVAL;
+
+=09return count;
+}
+
+static ssize_t charge_control_end_threshold_show(struct device *dev,
+=09=09=09=09struct device_attribute *attr,
+=09=09=09=09char *buf)
+{
+=09int status;
+=09status =3D call_fext_func(fext, FUNC_S006_METHOD,
+=09=09=09=09CHARGE_CONTROL_RW, 0x21, 0x0);
+
+=09return sprintf(buf, "%d\n", status);
+}
+
+static DEVICE_ATTR_RW(charge_control_end_threshold);
+
+/* ACPI battery hook */
+
+static int fujitsu_battery_add(struct power_supply *battery,
+=09=09=09       struct acpi_battery_hook *hook)
+{
+=09/* Check if there is an existing FUJ02E3 ACPI device. */
+=09if (fext =3D=3D NULL)
+=09=09return -ENODEV;
+
+=09/*
+=09 * Check if the S006 0x21 method exists by trying to get the current
+=09 * battery charge limit.
+=09 */
+=09int s006_cc_return;
+=09s006_cc_return =3D call_fext_func(fext, FUNC_S006_METHOD,
+=09=09=09=09=09CHARGE_CONTROL_RW, 0x21, 0x0);
+=09if (s006_cc_return =3D=3D UNSUPPORTED_CMD)
+=09=09return -ENODEV;
+
+=09if (device_create_file(&battery->dev,
+=09=09=09       &dev_attr_charge_control_end_threshold))
+=09=09return -ENODEV;
+
+=09return 0;
+}
+
+static int fujitsu_battery_remove(struct power_supply *battery,
+=09=09=09=09  struct acpi_battery_hook *hook)
+{
+=09device_remove_file(&battery->dev,
+=09=09=09   &dev_attr_charge_control_end_threshold);
+
+=09return 0;
+}
+
+static struct acpi_battery_hook battery_hook =3D {
+=09.add_battery =3D fujitsu_battery_add,
+=09.remove_battery =3D fujitsu_battery_remove,
+=09.name =3D "Fujitsu Battery Extension",
+};
+
 /* Hardware access for LCD brightness control */
=20
 static int set_lcd_level(struct acpi_device *device, int level)
@@ -839,6 +930,8 @@ static int acpi_fujitsu_laptop_add(struct acpi_device *=
device)
 =09if (ret)
 =09=09goto err_free_fifo;
=20
+=09battery_hook_register(&battery_hook);
+
 =09return 0;
=20
 err_free_fifo:
@@ -851,6 +944,8 @@ static void acpi_fujitsu_laptop_remove(struct acpi_devi=
ce *device)
 {
 =09struct fujitsu_laptop *priv =3D acpi_driver_data(device);
=20
+=09battery_hook_unregister(&battery_hook);
+
 =09fujitsu_laptop_platform_remove(device);
=20
 =09kfifo_free(&priv->fifo);
--=20
2.43.0