[PATCH] platform/x86:dell-laptop: Add knobs to change battery charge settings

Andres Salomon
2024-07-20T05:28:52Z

The Dell BIOS allows you to set custom charging modes, which is useful
in particular for extending battery life. This adds support for tweaking
those various settings from Linux via sysfs knobs. One might, for
example, have their laptop plugged into power at their desk the vast
majority of the time and choose fairly aggressive battery-saving
settings (only charging once the battery drops to 50% and only charging
up to 80%). When leaving for a trip, they might want to switch those
settings to charge to 100% and charge any time power is available;
rebooting into the BIOS to change those settings is a hassle.

For the Custom charging type mode, we reuse the common
charge_control_{start,end}_threshold sysfs power_supply entries. The
BIOS also has a bunch of other charging modes with varying levels of
usefulness, so this adds a new Dell-specific sysfs entry called
'charge_type' that's documented in sysfs-class-power-dell (and looks a
lot like sysfs-class-power-wilco).

This work is based on a patch by Perry Yuan <perry_yuan@dell.com> and
Limonciello Mario <Mario_Limonciello@Dell.com> submitted back in 2020:
https://lore.kernel.org/all/20200729065424.12851-1-Perry_Yuan@Dell.com/
Both of their email addresses bounce, so I'm assuming they're no longer
with the company. I've reworked most of the patch to make it smaller and
cleaner.

Signed-off-by: Andres Salomon <dilinger@queued.net>
---
.../ABI/testing/sysfs-class-power-dell | 31 +++
drivers/platform/x86/dell/Kconfig | 1 +
drivers/platform/x86/dell/dell-laptop.c | 263 ++++++++++++++++++
drivers/platform/x86/dell/dell-smbios.h | 17 ++
4 files changed, 312 insertions(+)
create mode 100644 Documentation/ABI/testing/sysfs-class-power-dell

diff --git a/Documentation/ABI/testing/sysfs-class-power-dell b/Documentation/ABI/testing/sysfs-class-power-dell
new file mode 100644
index 000000000000..ef72c5f797ce
--- /dev/null
+++ b/Documentation/ABI/testing/sysfs-class-power-dell
@@ -0,0 +1,31 @@
+What: /sys/class/power_supply/<supply_name>/charge_type
+Date: July 2024
+KernelVersion: 6.11
+Contact: linux-pm@vger.kernel.org
+Description:
+ Select the charging algorithm to use for the (primary)
+ battery.
+
+ Standard:
+ Fully charge the battery at a moderate rate.
+ ExpressCharge™:
+ Quickly charge the battery using fast-charge
+ technology. This is harder on the battery than
+ standard charging and may lower its lifespan.
+ Primarily AC Use:
+ Users who primarily operate the system while
+ plugged into an external power source can extend
+ battery life with this mode.
+ Adaptive:
+ Automatically optimize battery charge rate based
+ on typical usage.
+ Custom:
+ Use the charge_control_* properties to determine
+ when to start and stop charging. Advanced users
+ can use this to drastically extend battery life.
+
+ Access: Read, Write
+ Valid values:
+ "standard", "express", "primarily_ac",
+ "adaptive", "custom"
+
diff --git a/drivers/platform/x86/dell/Kconfig b/drivers/platform/x86/dell/Kconfig
index 85a78ef91182..02405793163c 100644
--- a/drivers/platform/x86/dell/Kconfig
+++ b/drivers/platform/x86/dell/Kconfig
@@ -49,6 +49,7 @@ config DELL_LAPTOP
default m
depends on DMI
depends on BACKLIGHT_CLASS_DEVICE
+ depends on ACPI_BATTERY
depends on ACPI_VIDEO || ACPI_VIDEO = n
depends on RFKILL || RFKILL = n
depends on DELL_WMI || DELL_WMI = n
diff --git a/drivers/platform/x86/dell/dell-laptop.c b/drivers/platform/x86/dell/dell-laptop.c
index 6552dfe491c6..54f47b685a46 100644
--- a/drivers/platform/x86/dell/dell-laptop.c
+++ b/drivers/platform/x86/dell/dell-laptop.c
@@ -22,11 +22,13 @@
#include <linux/io.h>
#include <linux/rfkill.h>
#include <linux/power_supply.h>
+#include <linux/sysfs.h>
#include <linux/acpi.h>
#include <linux/mm.h>
#include <linux/i8042.h>
#include <linux/debugfs.h>
#include <linux/seq_file.h>
+#include <acpi/battery.h>
#include <acpi/video.h>
#include "dell-rbtn.h"
#include "dell-smbios.h"
@@ -98,6 +100,14 @@ static struct rfkill *wwan_rfkill;
static bool force_rfkill;
static bool micmute_led_registered;
static bool mute_led_registered;
+static enum battery_charging_mode bat_chg_current = DELL_BAT_MODE_NONE;
+static const char * const battery_state[DELL_BAT_MODE_MAX] = {
+ [DELL_BAT_MODE_STANDARD] = "standard",
+ [DELL_BAT_MODE_EXPRESS] = "express",
+ [DELL_BAT_MODE_PRIMARILY_AC] = "primarily_ac",
+ [DELL_BAT_MODE_ADAPTIVE] = "adaptive",
+ [DELL_BAT_MODE_CUSTOM] = "custom",
+};

module_param(force_rfkill, bool, 0444);
MODULE_PARM_DESC(force_rfkill, "enable rfkill on non whitelisted models");
@@ -2183,6 +2193,256 @@ static struct led_classdev mute_led_cdev = {
.default_trigger = "audio-mute",
};

+static int dell_battery_read_req(const int type, int *val)
+{
+ struct calling_interface_buffer buffer;
+ struct calling_interface_token *token;
+ int err;
+
+ token = dell_smbios_find_token(type);
+ if (!token)
+ return -ENODEV;
+
+ dell_fill_request(&buffer, token->location, 0, 0, 0);
+ err = dell_send_request(&buffer, CLASS_TOKEN_READ, SELECT_TOKEN_STD);
+ if (!err)
+ *val = buffer.output[1];
+
+ return err;
+}
+
+static int dell_battery_write_req(const int type, int val)
+{
+ struct calling_interface_buffer buffer;
+ struct calling_interface_token *token;
+
+ token = dell_smbios_find_token(type);
+ if (!token)
+ return -ENODEV;
+
+ dell_fill_request(&buffer, token->location, val, 0, 0);
+ return dell_send_request(&buffer,
+ CLASS_TOKEN_WRITE, SELECT_TOKEN_STD);
+}
+
+/* The rules: the minimum start charging value is 50%. The maximum
+ * start charging value is 95%. The minimum end charging value is
+ * 55%. The maximum end charging value is 100%. And finally, there
+ * has to be at least a 5% difference between start & end values.
+ */
+#define CHARGE_START_MIN 50
+#define CHARGE_START_MAX 95
+#define CHARGE_END_MIN 55
+#define CHARGE_END_MAX 100
+#define CHARGE_MIN_DIFF 5
+
+static int dell_battery_custom_set(const int type, int val)
+{
+ if (type == BAT_CUSTOM_CHARGE_START) {
+ int end = CHARGE_END_MAX;
+
+ if (val < CHARGE_START_MIN)
+ val = CHARGE_START_MIN;
+ else if (val > CHARGE_START_MAX)
+ val = CHARGE_START_MAX;
+
+ dell_battery_read_req(BAT_CUSTOM_CHARGE_END, &end);
+ if ((end - val) < CHARGE_MIN_DIFF)
+ val = end - CHARGE_MIN_DIFF;
+ } else if (type == BAT_CUSTOM_CHARGE_END) {
+ int start = CHARGE_START_MIN;
+
+ if (val < CHARGE_END_MIN)
+ val = CHARGE_END_MIN;
+ else if (val > CHARGE_END_MAX)
+ val = CHARGE_END_MAX;
+
+ dell_battery_read_req(BAT_CUSTOM_CHARGE_START, &start);
+ if ((val - start) < CHARGE_MIN_DIFF)
+ val = start + CHARGE_MIN_DIFF;
+ }
+
+ return dell_battery_write_req(type, val);
+}
+
+static int battery_charging_mode_set(enum battery_charging_mode mode)
+{
+ int err;
+
+ switch (mode) {
+ case DELL_BAT_MODE_STANDARD:
+ err = dell_battery_write_req(BAT_STANDARD_MODE_TOKEN, mode);
+ break;
+ case DELL_BAT_MODE_EXPRESS:
+ err = dell_battery_write_req(BAT_EXPRESS_MODE_TOKEN, mode);
+ break;
+ case DELL_BAT_MODE_PRIMARILY_AC:
+ err = dell_battery_write_req(BAT_PRI_AC_MODE_TOKEN, mode);
+ break;
+ case DELL_BAT_MODE_ADAPTIVE:
+ err = dell_battery_write_req(BAT_ADAPTIVE_MODE_TOKEN, mode);
+ break;
+ case DELL_BAT_MODE_CUSTOM:
+ err = dell_battery_write_req(BAT_CUSTOM_MODE_TOKEN, mode);
+ break;
+ default:
+ err = -EINVAL;
+ }
+
+ return err;
+}
+
+static ssize_t charge_type_show(struct device *dev,
+ struct device_attribute *attr,
+ char *buf)
+{
+ enum battery_charging_mode mode;
+ ssize_t count = 0;
+
+ for (mode = DELL_BAT_MODE_STANDARD; mode < DELL_BAT_MODE_MAX; mode++) {
+ if (battery_state[mode]) {
+ count += sysfs_emit_at(buf, count,
+ mode == bat_chg_current ? "[%s] " : "%s ",
+ battery_state[mode]);
+ }
+ }
+
+ /* convert the last space to a newline */
+ count--;
+ count += sysfs_emit_at(buf, count, "\n");
+
+ return count;
+}
+
+static ssize_t charge_type_store(struct device *dev,
+ struct device_attribute *attr,
+ const char *buf, size_t size)
+{
+ enum battery_charging_mode mode;
+ const char *label;
+ int ret = -EINVAL;
+
+ for (mode = DELL_BAT_MODE_STANDARD; mode < DELL_BAT_MODE_MAX; mode++) {
+ label = battery_state[mode];
+ if (label && sysfs_streq(label, buf))
+ break;
+ }
+
+ if (mode > DELL_BAT_MODE_NONE && mode < DELL_BAT_MODE_MAX) {
+ ret = battery_charging_mode_set(mode);
+ if (!ret) {
+ bat_chg_current = mode;
+ ret = size;
+ }
+ }
+
+ return ret;
+}
+
+static ssize_t charge_control_start_threshold_show(struct device *dev,
+ struct device_attribute *attr,
+ char *buf)
+{
+ int ret, start;
+
+ ret = dell_battery_read_req(BAT_CUSTOM_CHARGE_START, &start);
+ if (!ret)
+ ret = sysfs_emit(buf, "%d\n", start);
+
+ return ret;
+}
+
+static ssize_t charge_control_start_threshold_store(struct device *dev,
+ struct device_attribute *attr,
+ const char *buf, size_t size)
+{
+ int ret, start;
+
+ ret = kstrtoint(buf, 10, &start);
+ if (!ret)
+ ret = dell_battery_custom_set(BAT_CUSTOM_CHARGE_START, start);
+ if (!ret)
+ ret = size;
+
+ return ret;
+}
+
+static ssize_t charge_control_end_threshold_show(struct device *dev,
+ struct device_attribute *attr,
+ char *buf)
+{
+ int ret, end;
+
+ ret = dell_battery_read_req(BAT_CUSTOM_CHARGE_END, &end);
+ if (!ret)
+ ret = sysfs_emit(buf, "%d\n", end);
+
+ return ret;
+}
+
+static ssize_t charge_control_end_threshold_store(struct device *dev,
+ struct device_attribute *attr,
+ const char *buf, size_t size)
+{
+ int ret, end;
+
+ ret = kstrtouint(buf, 10, &end);
+ if (!ret)
+ ret = dell_battery_custom_set(BAT_CUSTOM_CHARGE_END, end);
+ if (!ret)
+ ret = size;
+
+ return ret;
+}
+
+static DEVICE_ATTR_RW(charge_control_start_threshold);
+static DEVICE_ATTR_RW(charge_control_end_threshold);
+static DEVICE_ATTR_RW(charge_type);
+
+static struct attribute *dell_battery_attrs[] = {
+ &dev_attr_charge_control_start_threshold.attr,
+ &dev_attr_charge_control_end_threshold.attr,
+ &dev_attr_charge_type.attr,
+ NULL,
+};
+ATTRIBUTE_GROUPS(dell_battery);
+
+static int dell_battery_add(struct power_supply *battery,
+ struct acpi_battery_hook *hook)
+{
+ return device_add_groups(&battery->dev, dell_battery_groups);
+}
+
+static int dell_battery_remove(struct power_supply *battery,
+ struct acpi_battery_hook *hook)
+{
+ device_remove_groups(&battery->dev, dell_battery_groups);
+ return 0;
+}
+
+static struct acpi_battery_hook dell_battery_hook = {
+ .add_battery = dell_battery_add,
+ .remove_battery = dell_battery_remove,
+ .name = "Dell Primary Battery Extension",
+};
+
+static void __init dell_battery_init(struct device *dev)
+{
+ enum battery_charging_mode current_mode = DELL_BAT_MODE_NONE;
+
+ dell_battery_read_req(BAT_CUSTOM_MODE_TOKEN, (int *) &current_mode);
+ if (current_mode != DELL_BAT_MODE_NONE) {
+ bat_chg_current = current_mode;
+ battery_hook_register(&dell_battery_hook);
+ }
+}
+
+static void __exit dell_battery_exit(void)
+{
+ if (bat_chg_current != DELL_BAT_MODE_NONE)
+ battery_hook_unregister(&dell_battery_hook);
+}
+
static int __init dell_init(void)
{
struct calling_interface_token *token;
@@ -2219,6 +2479,7 @@ static int __init dell_init(void)
touchpad_led_init(&platform_device->dev);

kbd_led_init(&platform_device->dev);
+ dell_battery_init(&platform_device->dev);

dell_laptop_dir = debugfs_create_dir("dell_laptop", NULL);
debugfs_create_file("rfkill", 0444, dell_laptop_dir, NULL,
@@ -2293,6 +2554,7 @@ static int __init dell_init(void)
if (mute_led_registered)
led_classdev_unregister(&mute_led_cdev);
fail_led:
+ dell_battery_exit();
dell_cleanup_rfkill();
fail_rfkill:
platform_device_del(platform_device);
@@ -2311,6 +2573,7 @@ static void __exit dell_exit(void)
if (quirks && quirks->touchpad_led)
touchpad_led_exit();
kbd_led_exit();
+ dell_battery_exit();
backlight_device_unregister(dell_backlight_device);
if (micmute_led_registered)
led_classdev_unregister(&micmute_led_cdev);
diff --git a/drivers/platform/x86/dell/dell-smbios.h b/drivers/platform/x86/dell/dell-smbios.h
index ea0cc38642a2..f7c07b4d72e3 100644
--- a/drivers/platform/x86/dell/dell-smbios.h
+++ b/drivers/platform/x86/dell/dell-smbios.h
@@ -33,11 +33,28 @@
#define KBD_LED_AUTO_50_TOKEN 0x02EB
#define KBD_LED_AUTO_75_TOKEN 0x02EC
#define KBD_LED_AUTO_100_TOKEN 0x02F6
+#define BAT_PRI_AC_MODE_TOKEN 0x0341
+#define BAT_ADAPTIVE_MODE_TOKEN 0x0342
+#define BAT_CUSTOM_MODE_TOKEN 0x0343
+#define BAT_STANDARD_MODE_TOKEN 0x0346
+#define BAT_EXPRESS_MODE_TOKEN 0x0347
+#define BAT_CUSTOM_CHARGE_START 0x0349
+#define BAT_CUSTOM_CHARGE_END 0x034A
#define GLOBAL_MIC_MUTE_ENABLE 0x0364
#define GLOBAL_MIC_MUTE_DISABLE 0x0365
#define GLOBAL_MUTE_ENABLE 0x058C
#define GLOBAL_MUTE_DISABLE 0x058D

+enum battery_charging_mode {
+ DELL_BAT_MODE_NONE = 0,
+ DELL_BAT_MODE_STANDARD,
+ DELL_BAT_MODE_EXPRESS,
+ DELL_BAT_MODE_PRIMARILY_AC,
+ DELL_BAT_MODE_ADAPTIVE,
+ DELL_BAT_MODE_CUSTOM,
+ DELL_BAT_MODE_MAX,
+};
+
struct notifier_block;

struct calling_interface_token {
--
2.39.2

--
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