On Fri, 21 May 2021 19:14:17 +0200
Hans de Goede <hdegoede@xxxxxxxxxx> wrote:
> Some 360 degree hinges (yoga) style 2-in-1 devices use 2 bmc150 accels
> to allow the OS to determine the angle between the display and the base
> of the device, so that the OS can determine if the 2-in-1 is in laptop
> or in tablet-mode.
>
> On Windows both accelerometers are read (polled) by a special service
> and this service calls the DSM (Device Specific Method), which in turn
> translates the angles to one of laptop/tablet/tent/stand mode and then
> notifies the EC about the new mode and the EC then enables or disables
> the builtin keyboard and touchpad based in the mode.
>
> When the 2-in-1 is powered-on or resumed folded in tablet mode the
> EC senses this independent of the DSM by using a HALL effect sensor
> which senses that the keyboard has been folded away behind the display.
>
> At power-on or resume the EC disables the keyboard based on this and
> the only way to get the keyboard to work after this is to call the
> DSM to re-enable it.
>
> Call the DSM on probe() and resume() to fix the keyboard not working
> when powered-on / resumed in tablet-mode.
>
> This patch was developed and tested on a Lenovo Yoga 300-IBR.
>
> Signed-off-by: Hans de Goede <hdegoede@xxxxxxxxxx>
Putting aside my general grumpiness at this stuff having to pollute
accelerometer drivers (and the broken DSM implementation on the hardware!)
this is a fairly clean implementation so I guess we can survive it.
Jonathan
> ---
> drivers/iio/accel/bmc150-accel-core.c | 3 +
> drivers/iio/accel/bmc150-accel-i2c.c | 109 ++++++++++++++++++++++++++
> drivers/iio/accel/bmc150-accel.h | 3 +
> 3 files changed, 115 insertions(+)
>
> diff --git a/drivers/iio/accel/bmc150-accel-core.c b/drivers/iio/accel/bmc150-accel-core.c
> index 0291512648b2..932007895f18 100644
> --- a/drivers/iio/accel/bmc150-accel-core.c
> +++ b/drivers/iio/accel/bmc150-accel-core.c
> @@ -1803,6 +1803,9 @@ static int bmc150_accel_resume(struct device *dev)
> bmc150_accel_fifo_set_mode(data);
> mutex_unlock(&data->mutex);
>
> + if (data->resume_callback)
> + data->resume_callback(dev);
> +
> return 0;
> }
> #endif
> diff --git a/drivers/iio/accel/bmc150-accel-i2c.c b/drivers/iio/accel/bmc150-accel-i2c.c
> index 1dd7b8a9a382..31256c32a33c 100644
> --- a/drivers/iio/accel/bmc150-accel-i2c.c
> +++ b/drivers/iio/accel/bmc150-accel-i2c.c
> @@ -28,6 +28,107 @@ static const struct acpi_device_id bmc150_acpi_dual_accel_ids[] = {
> { },
> };
>
> +/*
> + * The DUAL250E ACPI device for 360° hinges type 2-in-1s with 1 accelerometer
> + * in the display and 1 in the hinge has an ACPI-method (DSM) to tell the
> + * ACPI code about the angle between the 2 halves. This will make the ACPI
> + * code enable/disable the keyboard and touchpad. We need to call this to avoid
> + * the keyboard being disabled when the 2-in-1 is turned-on or resumed while
> + * fully folded into tablet mode (which gets detected with a HALL-sensor).
> + * If we don't call this then the keyboard won't work even when the 2-in-1 is
> + * changed to be used in laptop mode after the power-on / resume.
> + *
> + * This DSM takes 2 angles, selected by setting aux0 to 0 or 1, these presumably
> + * define the angle between the gravity vector measured by the accelerometer in
> + * the display (aux0=0) resp. the base (aux0=1) and some reference vector.
> + * The 2 angles get subtracted from each other so the reference vector does
> + * not matter and we can simply leave the second angle at 0.
> + */
> +
> +#define BMC150_DSM_GUID "7681541e-8827-4239-8d9d-36be7fe12542"
> +#define DUAL250E_SET_ANGLE_FN_INDEX 3
> +
> +struct dual250e_set_angle_args {
> + u32 aux0;
> + u32 ang0;
> + u32 rawx;
> + u32 rawy;
> + u32 rawz;
> +} __packed;
> +
> +static bool bmc150_acpi_set_angle_dsm(struct i2c_client *client, u32 aux0, u32 ang0)
> +{
> + struct acpi_device *adev = ACPI_COMPANION(&client->dev);
> + struct dual250e_set_angle_args args = {
> + .aux0 = aux0,
> + .ang0 = ang0,
> + };
> + union acpi_object args_obj, *obj;
> + guid_t guid;
> +
> + if (strcmp(acpi_device_hid(adev), "DUAL250E"))
> + return false;
> +
> + guid_parse(BMC150_DSM_GUID, &guid);
> +
> + if (!acpi_check_dsm(adev->handle, &guid, 0, BIT(DUAL250E_SET_ANGLE_FN_INDEX)))
> + return false;
> +
> + /*
> + * Note this triggers the following warning:
> + * "ACPI Warning: \_SB.PCI0.I2C2.ACC1._DSM: Argument #4 type mismatch -
> + * Found [Buffer], ACPI requires [Package]"
> + * This is unavoidable since the _DSM implementation expects a "naked"
> + * buffer, so wrapping it in a package will _not_ work.
ouch.
> + */
> + args_obj.type = ACPI_TYPE_BUFFER;
> + args_obj.buffer.length = sizeof(args);
> + args_obj.buffer.pointer = (u8 *)&args;
> +
> + obj = acpi_evaluate_dsm(adev->handle, &guid, 0, DUAL250E_SET_ANGLE_FN_INDEX, &args_obj);
> + if (!obj) {
> + dev_err(&client->dev, "Failed to call DSM to enable keyboard and touchpad\n");
> + return false;
> + }
> +
> + ACPI_FREE(obj);
> + return true;
> +}
> +
> +static bool bmc150_acpi_enable_keyboard(struct i2c_client *client)
> +{
> + /*
> + * The EC must see a change for it to re-enable the kbd, so first set the
> + * angle to 270° (tent/stand mode) and then change it to 90° (laptop mode).
> + */
> + if (!bmc150_acpi_set_angle_dsm(client, 0, 270))
> + return false;
> +
> + /* The EC needs some time to notice the angle being changed */
> + msleep(100);
> +
> + return bmc150_acpi_set_angle_dsm(client, 0, 90);
> +}
> +
> +static void bmc150_acpi_resume_work(struct work_struct *work)
> +{
> + struct bmc150_accel_data *data =
> + container_of(work, struct bmc150_accel_data, resume_work.work);
> +
> + bmc150_acpi_enable_keyboard(data->second_device);
> +}
> +
> +static void bmc150_acpi_resume_handler(struct device *dev)
> +{
> + struct bmc150_accel_data *data = iio_priv(dev_get_drvdata(dev));
> +
> + /*
> + * Delay the bmc150_acpi_enable_keyboard() call till after the system
> + * resume has completed, otherwise it will not work.
> + */
> + schedule_delayed_work(&data->resume_work, msecs_to_jiffies(1000));
> +}
> +
> /*
> * Some acpi_devices describe 2 accelerometers in a single ACPI device, try instantiating
> * a second i2c_client for an I2cSerialBusV2 ACPI resource with index 1.
> @@ -55,12 +156,20 @@ static void bmc150_acpi_dual_accel_probe(struct i2c_client *client)
> board_info.irq = acpi_dev_gpio_irq_get_by(adev, NULL, 1);
>
> data->second_device = i2c_acpi_new_device(&client->dev, 1, &board_info);
> +
> + if (!IS_ERR(data->second_device) && bmc150_acpi_enable_keyboard(data->second_device)) {
> + INIT_DELAYED_WORK(&data->resume_work, bmc150_acpi_resume_work);
> + data->resume_callback = bmc150_acpi_resume_handler;
> + }
> }
>
> static void bmc150_acpi_dual_accel_remove(struct i2c_client *client)
> {
> struct bmc150_accel_data *data = iio_priv(i2c_get_clientdata(client));
>
> + if (data->resume_callback)
> + cancel_delayed_work_sync(&data->resume_work);
> +
> i2c_unregister_device(data->second_device);
> }
> #else
> diff --git a/drivers/iio/accel/bmc150-accel.h b/drivers/iio/accel/bmc150-accel.h
> index 5da6fd32bac5..d67d6ed6ae77 100644
> --- a/drivers/iio/accel/bmc150-accel.h
> +++ b/drivers/iio/accel/bmc150-accel.h
> @@ -6,6 +6,7 @@
> #include <linux/iio/iio.h>
> #include <linux/mutex.h>
> #include <linux/regulator/consumer.h>
> +#include <linux/workqueue.h>
>
> struct regmap;
> struct i2c_client;
> @@ -62,6 +63,8 @@ struct bmc150_accel_data {
> int64_t timestamp, old_timestamp; /* Only used in hw fifo mode. */
> const struct bmc150_accel_chip_info *chip_info;
> struct i2c_client *second_device;
> + void (*resume_callback)(struct device *dev);
> + struct delayed_work resume_work;
> struct iio_mount_matrix orientation;
> };
>
