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Message-ID: <e305a170-362d-48bb-a742-f4c8f010b2c7@redhat.com>
Date: Wed, 7 Feb 2024 09:57:21 +0100
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Subject: Re: [RFC PATCH v3] platform/x86/fujitsu-laptop: Add battery charge
 control support
To: Szilard Fabian <szfabian@bluemarch.art>, linux-kernel@vger.kernel.org,
 platform-driver-x86@vger.kernel.org, jwoithe@just42.net,
 ilpo.jarvinen@linux.intel.com, W_Armin@gmx.de,
 Jelle van der Waa <jelle@vdwaa.nl>
References: <20240129163502.161409-2-szfabian@bluemarch.art>
 <20240129175714.164326-2-szfabian@bluemarch.art>
 <20240207023031.56805-2-szfabian@bluemarch.art>
Content-Language: en-US, nl
From: Hans de Goede <hdegoede@redhat.com>
In-Reply-To: <20240207023031.56805-2-szfabian@bluemarch.art>
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Hi Szilard,

+Cc Jelle van der Waa who has been working on userspace (upower + GNOME)
support for these thresholds.

On 2/7/24 03:32, Szilard Fabian wrote:
> 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.
> 
> Signed-off-by: Szilard Fabian <szfabian@bluemarch.art>

Thank you for your patch. Do you happen to know if there also
is a noticeable fixed start threshold which is like say always 5%
lower then then end threshold ?

Note I'm *not* asking you to also add a start threshold attribute
at this time. But we (Jelle and me mostly atm) are thinking about
a way to export the start threshold offset in cases like this
to userspace.

Regards,

Hans


> ---
> v3:
> * added additional error handling
> * removed if statement with device_create_file(), just returning that
>   function instead
> * added bool charge_control_supported into struct fujitsu_laptop
> * added a 'charge_control_add' and 'charge_control_remove' function to be
>   called from acpi_fujitsu_laptop_add() and acpi_fujitsu_laptop_remove()
> * moved FUJ02E3 S006 probing logic from the ACPI battery hooks to the new
>   'charge_control_*' functions
> 
> v2:
> Forgot to sign-off the original commit. Fixed, sorry for the
> inconvenience.
> ---
>  drivers/platform/x86/fujitsu-laptop.c | 125 ++++++++++++++++++++++++++
>  1 file changed, 125 insertions(+)
> 
> diff --git a/drivers/platform/x86/fujitsu-laptop.c b/drivers/platform/x86/fujitsu-laptop.c
> index 085e044e888e..2fcbc10a0d9d 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>
>  
>  #define FUJITSU_DRIVER_VERSION		"0.6.0"
> @@ -97,6 +99,10 @@
>  #define BACKLIGHT_OFF			(BIT(0) | BIT(1))
>  #define BACKLIGHT_ON			0
>  
> +/* FUNC interface - battery control interface */
> +#define FUNC_S006_METHOD		0x1006
> +#define CHARGE_CONTROL_RW		0x21
> +
>  /* Scancodes read from the GIRB register */
>  #define KEY1_CODE			0x410
>  #define KEY2_CODE			0x411
> @@ -132,6 +138,7 @@ struct fujitsu_laptop {
>  	spinlock_t fifo_lock;
>  	int flags_supported;
>  	int flags_state;
> +	bool charge_control_supported;
>  };
>  
>  static struct acpi_device *fext;
> @@ -164,6 +171,118 @@ static int call_fext_func(struct acpi_device *device,
>  	return value;
>  }
>  
> +/* Battery charge control code */
> +
> +static ssize_t charge_control_end_threshold_store(struct device *dev,
> +				struct device_attribute *attr,
> +				const char *buf, size_t count)
> +{
> +	int value, ret;
> +
> +	ret = kstrtouint(buf, 10, &value);
> +	if (ret)
> +		return ret;
> +
> +	if (value < 50 || value > 100)
> +		return -EINVAL;
> +
> +	int cc_end_value, s006_cc_return;
> +
> +	cc_end_value = value * 0x100 + 0x20;
> +	s006_cc_return = call_fext_func(fext, FUNC_S006_METHOD,
> +					CHARGE_CONTROL_RW, cc_end_value, 0x0);
> +
> +	if (s006_cc_return < 0)
> +		return s006_cc_return;
> +
> +	/*
> +	 * The S006 0x21 method returns 0x00 in case the provided value
> +	 * is invalid.
> +	 */
> +	if (s006_cc_return == 0x00)
> +		return -EINVAL;
> +
> +	return count;
> +}
> +
> +static ssize_t charge_control_end_threshold_show(struct device *dev,
> +				struct device_attribute *attr,
> +				char *buf)
> +{
> +	int status;
> +	status = call_fext_func(fext, FUNC_S006_METHOD,
> +				CHARGE_CONTROL_RW, 0x21, 0x0);
> +
> +	if (status < 0)
> +		return status;
> +
> +	return sprintf(buf, "%d\n", status);
> +}
> +
> +static DEVICE_ATTR_RW(charge_control_end_threshold);
> +
> +/* ACPI battery hook */
> +
> +static int fujitsu_battery_add_hook(struct power_supply *battery,
> +			       struct acpi_battery_hook *hook)
> +{
> +	return device_create_file(&battery->dev,
> +				  &dev_attr_charge_control_end_threshold);
> +}
> +
> +static int fujitsu_battery_remove_hook(struct power_supply *battery,
> +				  struct acpi_battery_hook *hook)
> +{
> +	device_remove_file(&battery->dev,
> +			   &dev_attr_charge_control_end_threshold);
> +
> +	return 0;
> +}
> +
> +static struct acpi_battery_hook battery_hook = {
> +	.add_battery = fujitsu_battery_add_hook,
> +	.remove_battery = fujitsu_battery_remove_hook,
> +	.name = "Fujitsu Battery Extension",
> +};
> +
> +/*
> + * These functions are intended to be called from acpi_fujitsu_laptop_add and
> + * acpi_fujitsu_laptop_remove.
> + */
> +
> +static int fujitsu_battery_charge_control_add(struct acpi_device *device)
> +{
> +	struct fujitsu_laptop *priv = acpi_driver_data(device);
> +	priv->charge_control_supported = false;
> +
> +	/*
> +	 * Check if the S006 0x21 method exists by trying to get the current
> +	 * battery charge limit.
> +	 */
> +	int s006_cc_return;
> +	s006_cc_return = call_fext_func(fext, FUNC_S006_METHOD,
> +					CHARGE_CONTROL_RW, 0x21, 0x0);
> +
> +	if (s006_cc_return < 0)
> +		return s006_cc_return;
> +
> +	if (s006_cc_return == UNSUPPORTED_CMD)
> +		return -ENODEV;
> +
> +	priv->charge_control_supported = true;
> +	battery_hook_register(&battery_hook);
> +
> +	return 0;
> +}
> +
> +static void fujitsu_battery_charge_control_remove(struct acpi_device *device)
> +{
> +	struct fujitsu_laptop *priv = acpi_driver_data(device);
> +
> +	if (priv->charge_control_supported)
> +		battery_hook_unregister(&battery_hook);
> +}
> +
>  /* Hardware access for LCD brightness control */
>  
>  static int set_lcd_level(struct acpi_device *device, int level)
> @@ -839,6 +958,10 @@ static int acpi_fujitsu_laptop_add(struct acpi_device *device)
>  	if (ret)
>  		goto err_free_fifo;
>  
> +	ret = fujitsu_battery_charge_control_add(device);
> +	if (ret < 0)
> +		pr_warn("Unable to register battery charge control: %d\n", ret);
> +
>  	return 0;
>  
>  err_free_fifo:
> @@ -851,6 +974,8 @@ static void acpi_fujitsu_laptop_remove(struct acpi_device *device)
>  {
>  	struct fujitsu_laptop *priv = acpi_driver_data(device);
>  
> +	fujitsu_battery_charge_control_remove(device);
> +
>  	fujitsu_laptop_platform_remove(device);
>  
>  	kfifo_free(&priv->fifo);